foraminifera from the pecten conglomerate

FORAMINIFERA FROM THE PECTEN CONGLOMERATE
(PLIOCENE) OF COCKBURN ISLAND,
ANTARCTIC PENINSULA
AN DRZEJ GAZDZ IC K I and PETER-N OEL WEBB
Gaz d zicki . A . a nd We b b . P- N. 19 9 6 . Fora mini fe ra from the Pect en Co ng lo me rate
( Plioce ne) o f Cock b urn Isl and . A nta rctic Peninsul a.J». A . G az dz ic ki (ed .) Pala eo nt ol o g ic al
Resul ts o r the Pol ish A nta rc tic Expe d ition s. Pa rt If. - Palacont ol ogi« Poloni ca SS.
14 7-1 74 .
T he Pect en Co ng lo me rate wa s first pr o po sed a nd de scribed by Ande rsso n ( 1906) at a ty pe
local ity on Coc kbu rn Isl an d . a s ma ll isl and s ituated be twee n l am e s Ross a nd Se ym our
Isl an d s. An tarc tic Pe ni nsu la. T he na me or the fo rmatio n is taken fro m the b ival ve Chlatnvs
audcrsson i ( Henn ig, 191 0 ) w hic h occ ur s in ab unda nce at the type loc al ity. In the first
pu bl ic at ion on the turam ini lc ra recovered fro m th is uni t. Holl a nd ( 19 10) described and
illu strated a fa u na o r X ge ne ra and II s pe c ies . Early in vest igat or s e m p loyed muc ro pa lco nto log ic al and pa leocl ima tic dat a in assig ning eit her a P liocc ne or Pl ei st occn c age to the
torm atio n and pa leon to logi st s agreed th at th e Pecten Co ng lomera te rep res e nte d an int e rg lac ia l or pre -g lac ia l enviro nme nt. In the pr ese nt investig atio n of th e to ra miui te ra . the
di ve rs ity ha s been augment ed to 19 ge ne ra an d 24 spec ies . T he assem b lage c o nta ins onl y
c a lcareo us bent hic ta xa . Ag g lut inated and plan kiic ta xa arc no t present. Rich assemb lag e s
o r mucro fuuna and m icro fau nu/ fl nra in the Pecten Con g lo merate prov ide a biot op e o f more
th an 100 spec ies. Hi gh e nergy. coas ta l mar in e e nv iro nm en ts w ith wa te r depths not exce eding 50 me ter s are dedu ced fro m Iora m in ifera l a nd othe r palcon tol og icul dat a . T he re is no
e vide nce Ior th e presen ce o r thick gro un ded ice s heets o r ice she lves o ver thi s area d ur in g
dep os itio n. a lthou g h th e occ urre nce of seas o na l sea- ice ca nno t be di sco unte d . T he Iora mi ni feral asse mb lage is corre late d w ith a lmo st ide ntica l Pli ocen e asse mb lag e s from the
Wr igh t and Tayl or Valley s. a nd so uthern and wes tern M r Murdo So und . and Lar sem ann
H ills near Pryd z Ba y. Ea st A nta rctica. Di a tom s w hic h eo -occ ur w ith th e Cock burn Isl an d
Ioru mi nifera indicate a n age o r 2.X- 2. 0 Ma ( late Pl ioceu e ) a nd K/ A r radio me tric age s or
3 .65 and 2 .8 M a (late Pli occ nc ) were obta ined trorn basalt s w hich re sp ect ive ly und e rlie
and po ssib ly ov er lie the Pecten C o ng lo me ra te . Pal eo ntol og ical da ta ind ic ate dcg lac ia l/i ntcrg lacia l condi tion s a t latitu de 64 "S in th e A ntarct ic Penins ula. an d support arg um en ts
ravori ng re lat ive ly m ild po lar c limate in man y part s of An tarctica duri ng the Pli o cen e.
K e y wo r d s : Foram inifera . pa lco eco log y, Pl iocen e . g lacial-de gfacia l hi st o ry. An ta rc tic a.
A ndr; «] Ga -;"~ ick i , Inst vtut Pal cob iol ogii PA N. A lc]a Z\I'irk i i Wigllrr 93, 0 2 -0 S 9 WlIrS~l/I \,({ ,
Pol(//ul,
Peter-Noel Wel>!l, Dep a rtm en t o] ( ;eol og ical Sci ences cu u ] Ur n! Pol a r Research Ccntcr.
nil' Ohio S/a /e Uni vcrsitv, Co lumhus. Ohio -I32! O, U S, A .
k cccivcd
l)
Sept e mber 1l)t)5. accepted 3 1 Octobe r 1995
148
ANDRZEl GAZDZICKI and PETER-NOEL WEBB
CONTENTS
Introduction
149
Acknowledgements
149
150
Geology of Coc kburn Island
Geog raphy .
150
Strati graph y
150
Marambio Group (Lopez de Bertodano Formation) and the La Meseta Formation: Upper Cretaceous and Eocene ·.
150
Coc kburn Unconformity U4 : Faulting or unconformity betw een Cretaceou s and Terti ary sed iments
150
Cockburn Unconformity U, : Olig ocene-Miocen e or lower Pliocen e eros ion surface
152
lames Ross Island Volc anic Group : Pliocene
152
Coc kburn Unconforrnity U 2: upper Pliocene
153
Pecten Conglom erat e: upper Pliocene
154
. . .
Coc kburn Unconformity U1 : uppermost Pliocene-Pl cistocene
Pect en Co nglomerate (ANDERSSO N, 1906)
154
154
Origin al descript ion . . . . . . .
154
Type area and stratoty pe section
154
Litholo gy
154
Age ass ignments in ea rly literature
155
Age adopted here
156
Foramin ifera
. . . .
157
Introductory remarks
157
Sample material used in the present study
158
Sys tematic notes . . . . . . . . . . . . . .
158
Fam ily Spirillinidae REUSS et FRITSCII. 1861
158
Genus Pat ellina WILLl AMSON. 1858
158
Family Hauerinidae SCIIWAGER. 1876 . .
159
Subfamily Mili olin ellin ae VELLA, 1957
159
Genu s Pyrg o DEFRANCE. 1824
159
Genu s Triloculina D·O RBI (;NY. 1826
160
Family Nodosariidae EIIRENBER(;. 1838
160
Genu s Lenticulina LAM ARCK. 1804
160
Genu s Pseudonodosaria BOOM(;ART. 1949
Family Ellipso lageninidae A. S II.VESTR I. 1923
160
160
Genus Fissurina REUSS. 1850 . .
160
Genu s Oo lina f)' O RB IG NY . 1839
161
Family Cass idulinidae D·O RBI(;NY. 1839
161
Genu s Cassid ulina D'ORBI (;NY. 1826
161
Genus Cassidulinoides CUS IIMAN . 1927
161
Genu s Globocass idulina VOI.OSIII NOVA. 1960
161
Famil y Buliminidae HOFKER. 1951
Genu s A ugulogerina CUSIIMAN . 1927
Famil y Fursenkoinidae LOEBLlCII et T AI'I'AN . 1961
Genus Fursenkoina LOEBI.ICII et TAI'PAN. 1961
Famil y Pseud op arrellinidae VOLOSIII NOV A. 1952 . .
Genu s Epi stominella HLJ SEZIM A et MARUH ASI . 1944
Fam ily Di scorbinellid ae SIGAL. 1952
Genu s Discorbinella CUSIIM AN et MARTI N, 1935
162
162
162
162
162
162
162
162
FORAMINIFERA FROM TH E PECTEN CO NG LO MERATE
Fa m ily C ibici d ida e C USIIM AN. 1927 . . . .
149
16 2
Ge n us Cibicides DE MONTFORT. 180 8
16 2
Fam ily Noni on idae SClIl ILTZE. 1854 . . .
16 3
Gen us Nonio nella C USIIMAN. 19 26 .
163
Ge nus Melonis DE MONTFORT. 180 8
163
Ge nus Cribrononion TII ,\ L ~l A N N . 194 7
163
Fa mi ly Elphid iidae G ALLOW AY. 19 33 . . .
164
Gen us Ammoelphidiel!a C ONATO et S H oRE. 19 74
164
Co m me nts on th e foramin ifera l asse m b lages
165
Co m par iso n o f th e Pecten Co ng lo merate fora m in ifera l asse mb lages wi th other A ntarc tic Pl ioccn e assem b lages
167
Mod ern -d ay pol ar for a m in ife ra l biot op e ana logs
16 8
Pal eoecol o gical inte rpre ta tion of mac rofo ssil s a nd mi c rofossil s from th e Pecten Co ng lo me rate
Total fossi I as se m b lag e
. . . . . . . . . . . . . . . . . . . . . . . . . . .
169
169
Bathymetry and terrestri al influen ces
169
Marin e pal eoclimate at littoral -inner s he lf s ite s d uring th e Lat e Pli occn e
169
Impli cat ion s for terre str ial pa leogeogra phy and paleot op ogr aphy
170
Impli cati on s for tect oni c hi story
170
Co ncl ud ing rem ark s
170
Referen ce s
171
. .. ..
INTRODUCTION
Th e Pecten Con glomer ate of Coc kburn Isl and ha s been o ne of th e more c ited stratigraphic units in
A ntarc tic lite rature over the past 90 yea rs. Thi s is a tribute to excelle nce of the orig ina l field work and
paleont ol ogic al coll ecting und ert aken by Otto NORDENSKJOI.J) 'S Swedi sh South Pol ar Exp edition ( 190 1- 1903) to the Snow Hill Island- Seym our Island-James Ross Island-Cockburn Island regi on of the northern
Antarcti c Penin sula ( NOR DENSKJOLl) 1905, 1920; NORDENSKJ()I.J) et al. 1905). To man y ea rly geo log ists, and
parti cul arl y' to paleobiogeo graphcr s, the Pecten Congl om erate repre sented th e rep osit o ry of the last hi gh
latitude period of relative warmth (Plioce ne) before th e advent of the Ice A ge (Ple istoce ne). While some
e leme nts o f thi s traditional sce nario are basicall y correct, we now understand that th e Pecten Con glomerate
and its div erse biota likel y represent o ne de glacial (intergl acial ) interval in a lon g cr yo spheric record which
exte nds back to at least the late Eoce nc and maybe ea rlie r. Th e Pecten Co ng lo merate has been mentioned in
man y re views of Antarctic geology (e.g. FAIRBRIIXiE 1952; HAR RI NGTON 1965), but littl e new information
has been add ed to th e ori gin al researc h o f the 1901-1 903 Swed ish South Pol ar Ex pe d ition.
Th e Pecten C on gl om er at e was fir st di sco vered by Dr. J . G unna r A NDERSSON and G ost a BODMAN during
their v isi t to Cockburn Isl and in O ct ob er 1903. Th e fir st publi sh ed de scripti on w as by A NDER SSON ( 1906)
in h is pap er On the ge o logy o] Gra luun Land. S am ples tak en during thi s vis it we re d istributed to
pa leo nto log ists in Europe fo r mon ogr aphi c tre atmen t. A pap er o n the foraminifera ex trac ted fro m a s ing le
sa m ple (co llec to r J. G . A ND ERSSON. Swed ish S outh Pol ar Ex pe di tio n S PE- Loca lity No . 12) w as publi shed
by HOLLAND ( 1910). A NDER SSON ( 1906) ass ig ne d a Pli occn e ag e to the Pect en Co ng lo merate o n the basi s
of its s up posed non -gl ac ial o rigi n, a nd the refore its prc- Plc istoce ne age ; a nd co rre la tio n w ith pectinid -bc aring sc d ime nts in So ut h A me rica , re ga rded as Pli occn e in age . Th e results of th e present study con firm
thc Pl io cen e age of the for ma tio n. but not e nt ire ly fo r th e re ason s ado pte d by J. Gunn ar A NDER SSON ( 1906).
More th an three-q uarte rs of a ce ntury ha ve e lapse d s ince HaLl .AND'S ( 19 10) pion ee rin g wo rk o n the
fora m inifc ra o f th e Pect en Cong lo me ra te . A re-exa m ina tio n o f th e fauna a nd an updating o f th e o rig ina l
systc m atic descri pti on s a nd gc nc ric and spec ies ass ig nat io ns see ms ove rd ue .
Acknowledgements. - Wc ac know ledge heli copter sup port pro vid ed by the U.S. Coas tg ua rd Cutter
Glacier in Mar ch 1982, during th e Nati on al Sci en ce Foundati on spo nso re d vis it to Seymour Island , Snow
Hill Isl and a nd Co c kburn Island; and helicopter sup po rt pro vid ed by Fu crza Aerea Argentina in January
1988, during th e joint A rge ntine- Po lish Ex pe d itio n. Or. WJ . Z INS ME ISTE R accompani ed Pet er-N. W EBB
150
AND RZEJ GAZDZICK I a nd PETER-NOEL WE BR
during field collection activities in 1982; and S.A . MARENSSI , S.J. PORI;BSKI and S.N. SANTIL LA NA assisted
Andrzej GAZDZI CKI on Coc kburn Island durin g 1988. Professor Vald ar JAANUSSON kindl y made the
co llec tions of the 1901-1903 Swedish So uth Polar Exped ition avail abl e for study and hosted Andrzej
GAZDZICKI 'S visit to the Naturhi stori ska Rik smu seet , Stoc kho lm in 1987. Or. C hristian H.I ORT, Dep artm ent
of Qu aternary Geo logy, University of Lund provided va luable background infor mation of the activ ities
and scie ntific per sonn el associated with the 1901 -1 903 Expe dit ion. We ackn owled ge the ass ista nce of
Ew a HARA, Institute of Paleobiology, Warszawa , in prep arati on of sa mples. Mariann e HEYN, Ute BOCK
and Gerh ard SCIIM IEDL of the A lfred Wegen er Institute, Brcm erh aven , ass isted us in sca nning elect ron
microscop e procedures. We would part icul arl y like to acknow ledge ass ista nce , use of facilities and warm
hospit alit y provided the authors by Professor Or. Diete r FOTTERER, Dr. Andreas MACKENSEN, a nd Or.
Wern er EHRMANN, all o f the Alfre d Wegene r Institut e, Brernerh a ven . Th e Alex ander vo n Hurnb oldt
Fo unda tion, Bonn (Bad Go des berg) awa rded ge nero us support to both authors du ring the co m pletio n of
this investigati on . Draft s of manu script we re rev iewe d by David M. HARWOOD, Ga ry S. WILSON and John
H. WRENN. Peter-N . WEBB undert ook thi s work with support from the Nati on al Science Found ation (Office
of Polar Program s) grants DPP/NSF 79-07043 and 89- 199 1OA.
GEOLOGY OF COCKBURN ISLAND
GEO G RA PHY
Cockburn Island lies 5 km north of Ca pe Bodm an , Sey rno ur Island , at latitude 64 °13'S and longitud e
56°50 ' E (Text-figs 1- 2). The geog raphic position of the island is unli kely to have cha nge d from these
coo rdinates during and since the Pliocene. Th e island is elonga te in map view a nd is abo ut 2.5 km across
at its wides t po int (Text-fig. 2). The low er part of the island rises from sea level as steep slopes , whereas
the upp er part ass umes the for m of a level meseta-lik e surface located app roximately 250 meter s above
sea level (Text-f ig. 3; ANDE RSSON 1906, p. 4 1, fig. 3; see also ZINSME ISTER and W EBB 1982, fig . I; DOKTOR
et al. 1988, pI. 11 : I ; GAZDZICKI 199 3, figs 1- 2). A co ne-shaped promont or y risin g approxi mate ly 450
meter s above se a level dominates the north western edge o f the meseta. Th e island 's d istin cti ve physiography result s from a prot ecti ve ca p of basalt ove rly ing loosel y co nso lidated Upper Cre taceo us and Eoce ne
sedime nts . Elevations cited here arc the sa me as first es timated by ANDERSSON and BODMAN in 190 3.
These have been wid ely acce pted by subse que nt wo rkers, but may require adj ustme nt.
ST RA T IG RA PH Y
Th e stra tigraphy of Coc kburn Island co nsists of fou r major roc k subdiv isions and four hiatu s inter val s,
recogni zed here as uncon formities (o r eros ion surfaces) a nd give n the notati on U I to U-I (Text- fig. 4 ).
M AR AMBI O G RO UP (LO PEZ D E BERT OD ANO FO RMAT ION)
A ND TH E LA M ES ET A FO RM ATI O N: U PPE R C RE TACEO US AN D EOCE NE
Foss il-bearing sediments of the Cretaceo us Marambi o (Lopez de Bertodano For mation) Gro up and the
Eoce ne La Meseta Formation are expose d in the lower slopes o f the island. Ear ly discussions of these rocks
and their foss ils on Coc kburn Island and adj ace nt island s were provided by ANDERSSON ( 1906), ANDERSSON
in BUCKM AN ( 19 10), HENNI G ( 1910) and WILCKENS (1924); and more recentl y by FELDMAN N and WOODBURNE( 1988), ASK INet al. ( 1991), CRAME et al. ( 1991 ), PIRRI Eet al . ( 1992), and BARNES and RIDI NG ( 1994) .
COC K BURN UN CON FORMITY U-I : FA U LT ING OR UNC ONFO RM IT Y
BETW EEN C RE TACE O US A ND T ER TI ARY SE DI MEN T S
The relationship between the Cretaceous and Terti ary sedime nts on Coc kburn Island IS Important in
co nsiderating late Pliocene-Pleistocene uplift history of the Pecte n Co nglomera te. Both fault and unconformable relationship s have been proposed. CROI-T ( 1947) prop osed that Cretaceo us and Tertiary sedime nts on
Coc kburn Island are separated by faulting. BIBB Y ( 1966 , fig. I) portra ys this fault as cutting both the
sedimentary and volcanic rocks, although he also comments (p. 34) , "No faulting of post-James Ross Island
151
FORA M IN IFE RA FRO M TH E PECTEN CONGL OM ERAT E
60'W
o
VegaI.
D
Weddell Sea
70 'S
James Ross I.
Cockbum Island
QO
~11 0urI.
o
6..1
~{ r s
()
,
Fig . I
Map of the Anta rct ic Pe ni nsul a. and the Cockb uru-Scymo ur- Jamcs Ro ss Islan ds regi o n.
Volcanic age, exce pt that observed in relation to Prince G ustav Channel, was obse rved by the writer" . NELSON
( 1975, map 1) co nfines a major fault on Coc kbu rn Island to the Cretaceo us and Tertiary sedimentary
success ion and does not invo lve the Pliocenc James Ross Island Volcanic Gro up. ANDERSSON ( 1906) and
ANDERSSON in BUCKMA N ( 1910) may also have recog nized this featu re (fa ult or unconformit y) on the eas tern
face of Cock burn Island . A NDER SSON in BUCKMAN ( 1910, p. 42 ; see also HENNI G 1910, p. 3), illustrated
Cretaceo us and Tertiary sed ime nts separated by a basa lt dyke in his now we ll-know n cross section of
Cock burn Island. ANDER SSON's ( 1910) re-interp retation of structura l relatio nships at this site followe d
BUCKM AN's recogniti on of Tertiary brachiopod s in what ANDERSSON co nsidered were Cre taceo us sedime nts.
ANDERSSON writes in BUCK tvlA N ( 1910, p. 42) , "T his remarka ble discovery pro ves that the beds of Cockburn
Island must have undergone dis locations. which brought Tertiary strata to the same le vel as those of
Cretaceous agc . In fact Mr NORIlENSK.J()LD o n ourjoint visit to Cock burn Island, so me days alter my discovery
of the different fossi liferous beds in this islan d. point ed out that the sandy beds in the slope above the
glauconite bank were dist urbed and con torted" . ELLlOT and RIESKE ( 1987) followe d ea rlier wor kers in
acce pting fault se parat ion of co ntiguous Cretaceo us and Tert iary strata on Cock burn Island. ASK IN et al.
( 1991, p. 101 ) note, however, "The steep co ntact betwee n the Cre taceous and Ter tiary strata on the eas t side
of Cockburn Island is not exposed, a lthough in a gully ju st above the shore to the north of the basalt spine,
the Tertiary beds lie uncon form ably on the older beds ." , and (p. 102), 'T he anomalously high dip s of the
Tertiary beds on Coc kburn Island are here regarded as largely prim ary and the unexposed steep co ntact on
the cas t side of the island as a poss ible uncon forrnity, probably a buttress uncon formi ty agai nst a paleocanyon
wall". BAR NES and RIDI NG (\ 994, figs 2 and 5) prov ide the most deta iled descr iption and mappin g of the
uncon forin able and fau lt relationship s betwee n Cretaceous and Ce nozo ic successions on Coc kburn Island.
We accept the uncon formi ty argument and show it as U4 in Text-fig. 4. Rejecti on of the argument for high
angle faulting o f Cretaceous, Eoce ne. and Pliocene roc ks rem oves the requ irem ent to ex plain the latest
Pliocene-Pleistocene uplift of the Pecten Co nglomerate by local fault displacem ent.
152
AND RZEJ GAZ DZICK I and PET ER-NO EL WEBB
-
- SPE 12
PNW l l
PNW 10
AGl
AG 2
AG3
PNW14
PNW13
PNW 12-
l km
Fi g. 2
Geo logic ma p o f Coc kbum Islan d. sho wing co llectio n sites of Pecten Co ng lome rate sa mples used in this investigation. Th e
orig ina l 1901-1 903 Swedish South Pol ar Ex ped itio n sample S PE 12 (A NIJ ER SSON 19( 6) was co llec ted as float blocks o n th e
lower slo pes of the island . The KlAr date o f 3.65 Ma was o bta ined fro m a sample of l am es Ross Islan d Vo lcan ic Gro up
basalt co llected stratigra phica lly bel o w samples PNW I0 and I I. Pre-Pecten Cong lome rate geo logy is taken from aerial
ph otograph s. ASK IN et al . (199 1). and BARNES and RIDI NG ( 1994).
COC KB U R N UN CON FORMITY U:- : OLl GOC EN E-MIOC EN E
OR LOW ER PLlOC ENE E RO S IO N S U RFACE
A high-rel ief eros ion surface (Unco nformity U:-) (Tex t-fig . 4) c uts across the Upper Cre taceous and
Eocene sedime nts (Z INSME ISTER and W EBB 1982, figs 1- 3). T he o rigin of thi s surface is une xpl ain ed . It
may ha ve res ulted fro m g lacial erosion and may have developed below sea level. Its precise age is poorl y
es tablished, but must be so mew here betw een the age of the yo unges t La Meseta Fo rma tio n sediments
(Eocene) and the oldest age for the l am es Ross Island Volc an ic G roup o n Cockburn Island (c urre ntly 3.65
Ma or mid Pliocen e, see below ). BIB BY (19 66, fig. 26) discu ssed an unconformity at a sim ilar stra tigra phic
positi on in the successions of western lames Ross Island and alluded to its form ati on below sea level.
l AME S RO SS ISL AND VOLC ANI C G RO UP: PLlOC EN E
Basalt flows of the l am es Ross Island Vo lcan ic Group ca p the up per part of the island and di spl ay an
irreg ular lower profile where they fill depression s abo ve Coc kburn Uncon forrnity U:- (Tex t-fig . 4) . Marin e
sedime ntary facies (w hic h contain ophiuro ids and an ec hino id) of the l am es Ross Isl and Volca nic Gr oup
(PIRR IE and S YKES 1987), and an und ated marin e tillite with Chlamys anderssoni bet ween the l ames Ross
Island Volc an ic Group and the und erl yin g Cretaceous sedirnents (SME LLl E et al. 1988), occ ur o n lames
Ross Island , but as yet have no eq uiva le nt in Cockburn Island str ati graph y (Tex t-fig. 4).
The oldes t age repo rted for the basalt fro m l am es Ross Island is 6.5 Ma (latest Miocene) see S ME LLlE
et al. ( 1988). The low errn ost basalt flow s o n Cockburn Island ha ve not been dated radi om et ricall y. A date
at this stra tigraphic level would allow the determination of the yo unges t age of Cockburn Unconformity
U:- (Tex t-f ig . 4) . Th e age of the basalt dyk e which cut s close to the Cretaceous- Tertiary co ntac t (Cockburn
Unco nfor mity U-t ) on the eas tern side of Coc kburn Island, menti on ed above and discu ssed by ANDERSSON
153
FORA M IN IFE RA FROM TH E PECTEN CO NG LOMERATE
~~ ~~fl
PNW 14
AG 1
AG 2
AG 3
PNW 10
PNW 11
1
12
Fig. 3
Photograph o f the so uthern and eas te rn sides of Cockb urn Island. show ing Upper Cretaceous and Terti ary sed ime nts on the
lower slopes . and near-hor izon tal l am es Ross Island Volca nic Group roc ks . Arrow ed are co llec tion sites of the Pecten
Co ng lomer ate. Samples pre fixed by PNW co llected by P.-N . WEBB (in 1982 ). AG by A. G" ZDZICKI (in 1988). SP E by
Swedi sh Sou th Polar Expediti on (in 1903 ). see also Tex t-fig. 2. Photograph taken fro m C ross Va lley. Se ymour Island
(February 1994 ).
( 19 10) , ASKIN et al . (1 991 ), BAR NES and RIDI NG (1994 ) and othe rs as part of the fa u lt and unconformity
di scu ssion s is not ye t determined . Is thi s dyke P1iocen e in age and doe s it foll ow an o ld fault plane that
was reacti vated during th e Pliocen e ; o r does it foll ow a zo ne of weakness associ ated with the uncon formity
di scu ssed by ASKIN et al. ( 199 1) and others?
A sa mp le of the uppermost basalt e xpo sed immedi atel y below the Pecten C on gl om erate yie lded a KJAr
rad iom etric age of 3.65 Ma (WEIlIl and A NDR EAS EN 19 86). A sa m ple co llected top ogr aphi cally high er th an
the sedime ntary outcro ps, a nd possibly stratigraphically younger, yie lde d a dat e of 2.8 M a (Randa ll
A . KELLER, O regon State Unive rsity, per son al co m munica tion). The multiple eve nt vo lca nism implied by
these two dates is possibl e in terms o f wha t we kno w of the l am es Ross Isl and Volcan ic G roup (SMELLlE
et al . 1988).
COC K B U RN UNC ONFO RM IT Y U2: U P PE R PLl O C E N E
A pro m ine nt near-h ori zo ntal be nc h (Coc kburn Unco nfo rmity U 2) is c ut into the basalt. approx ima te ly
250 mete rs a bove se a le vel o n the so uthe rn a nd eas te rn s ides of the meseta top (Z INS MEISTER and W EIlIl
1982, fig . 3) see Text -fig. 2. It is o n thi s ben ch th at remn ant s o f the Pecten Cong lo merate c ro p out
(Tex t-fig. 3). We deduce from th e radiome tr ic dates c ited a bov e, th at Cockburn Uncon formity U 2 (o r
ero sion s urface) and the Pecten Co ng lome rate a re yo unge r tha n 3 .65 Ma and poss ibl y o lder tha n 2.8 Ma
(i.e. upper Pli ocen e). It is unclear whe the r the de velopment of thi s e ros ion surface is co nte mpora neo us
with the dep ositi on of the Pecten Cong lome rate or wh eth er the two e ve nts are se parated by a short spa n
of late Pli ocen e tim e, i.e. ten s of thou sand s to severa l hundred thou sand years (see ZINSMEISTER and W EIlB
1982, fig. I; D OKTOR et al. 19 88, pI. 11 : 1).
154
A N D RZEJ GAZDZ IC K I and PETER- NO EL W EBB
PECT EN C O N G LO M E R A TE : UPP ER PLIO C EN E
See be low, a nd Text-fi g s 2-4.
C OC K B U R N U NC O N FO R M IT Y U I: U P P E R M OS T PLIOC ENE-PL E ISTO C EN E
Thi s s urface probab ly re sulted fro m multipl e g lac ia l eros io na l eve nts . The eros io n o f th e Pecten
Cong lo me rate and the upper s urface of the J am e s Ro ss Isl a nd Volcani c Gro up are a mo ng the fea tur es
produ ced by lat e g lac ia l d issec tion .
P ECTE N CO NG LOME RA TE (AN DE RSS ON, 1906 )
OR IG INAL D ES CR IPT ION
A t the ti me of his vis it to Coc kburn Is land. A NDE Rsso N noted b lock s o f fo ssi life ro us co ng lo m erat e
sc attered o n the ta lus slo pe s up to 160 met ers above se a le vel on th e e as te rn s ide of th e isl an d (Text-fig .
2 ). Gost a BODM AN. hi s co m pa nio n d uring the vis it. c limbe d to the top of th e me seta from the w estern s ide
o f th e isl a nd and fo u nd fra gment s o f pect inid o n th e me scta , but none of the ho st se d ime n t ill s itu.
A NDERSSO N c omment ed ( 1906, p. 5 1). "Ev ide ntly it cove rs o nly a s ma ll part o f th e pl at ea u, as th e bl ock s
o f the co ng lo me ra te ar e met w ith nowhere in th e s lo pes o f th e island. ex ce pt at Loca lity I T ii .e.. SP E 12
herein ). A NDER ssoN ( 1906) de ri ved th e nam e of th e formation from th e we ll preserved a nd ab unda nt
pectinid Mvo chlamvs auderss oni H ENNIG. 19 10 w h ic h occ ur re d in the flo at blo ck s reco vered from th e
ta lus s lo pe s (Tex t- figs 2-3) . HENNI G ( 191 0 ) a lso pro v id ed in form at ion o n lo cal geology and pet ro gr aph y.
so me of it origina l. so me a ppare ntly g lea ne d fro m co nve rsa tio ns w ith J. G unna r A DER SSON. a nd info rmat ion ta ken di rectl y fro m A ND ER SSON ( 1906).
TY PE A REA AN D ST RA TOTY PE SEC T ION
T he ty pe area is we ll-co ns tra ined . but a fo rma l type sect io n for the form at ion ha s ye t to be m easured .
T he best ex posu res occ ur ne ar the e xtre me southe rn and eastern lim its of the be nc h. We beli e ve th e
fo rma t ion cove rs th e e nt ire le ngth of th e ben ch an d is obsc u red by basa ltic d eb ris. The ex pos ure at th e
northeast co rne r o f th e be nc h pr o vid es a par tial sect io n th rou gh the se di me ntary s uccessio n a nd the co ntact
w ith the und erl y ing ba salt (ZI NSr-IEISTER and W EHH 19 lQ . fig . 3) (Coc kb urn U nco n for mi ty U 2 • Te xt - fig . 4 ).
We es tima te th e rem nant s uccess io n o f Pecten Cong lo me ra te to be so mewhe re be tween 5 and 10 m et ers
in thi ckne ss , but s ugges t, that becau se s urv ivi ng o utc ro ps may ha ve been pr ot ect ed from g lac ia l e ros io n
w ith in the be nc h dep re ssi on a nd mu c h of th e ex posed s uccess io n lat e r erode d . th e o rig ina l total th ickn es s
ma y ha ve been g reate r.
O the r th an a po ssibl e occ urre nce at Fio rdo Bcl en (DU . V,\ I.I .E et (/1. 19 87 ). no o ther o utcro ps o f the
Pect en Cong lo me rate a re know n in th e Jam es Ro ss a nd Scy mo u r Isl and s re gi on . A ND I ~R S SO N ( 1906, p. 63)
and a lso A NDER SSON in BUCKr-I AN ( 191 0 . p . 43) wa s proba bly correc t in conside ring the fo rmation to have
had a wide r di stributi on befo re destru ct ion by s ubseq ue nt g laci al d issection . BARTON ( 1965) a pp lie d th e
for ma tio n nam e to pecti nid -bearing se d ime nts in the Li on s Rump Gro up of Kin g George Isl an d (South
S he t la nd Is lands). G AZDZICK A a nd G AZDZICK I ( 1985). BIRKEN" IAJER a nd G AZDZICK I ( 1( 86 ) sho w ed these
sedi ment s to be O ligoce ne a nd no t Pl iocen e in age . The C ockburn Is la nd a nd K ing Gcorgc Isl a nd
pectin id-bear ing success io ns appear to be un rel at ed (BIRKENr-I AJER et al. 1( 91 ).
LI TH O LO G Y
At the northeast corner of th e be nc h o n Cockburn Isl a nd . the basal sed iment s co nsist o f coarse -grained .
po orl y so rted. a nd fine ly-bedded co ng lo me ra tic sa nd sto ne (Text - figs 5-6) . The c lasts in th e cong lo me rate
arc poorl y ro u nded pe bbl es a nd bo ulde rs of ba salti c co m pos it io n . Nearby. the coarse r cong lo meratic fac ies
is rep laced by fin er-grain ed . ora nge-brow n g rave lly sa nds to ne in w h ic h we ll- p rese rve d Ch/lIIllYS anderssoni ( HENNI(j) s he lls are pre sent (Text- fig . 5). Sc all op s he lls occ ur o n ly rare ly in the co ng lo mera tic Iac ics.
We d id not o bse rve exo tic c rys ta lline c las ts in o utcro ps. o r othe r ev ide nce for ice rafting. STEWART ( 193 7)
exam ine d a sa m ple of th e Pect en Cong lo me rate and not ed the pr e sen ce of comm on basa lti c m at eri a l and
FO RA M IN IFERA FRO M TH E PECTEN CONG LO MERATE
Age
Paleo ntol ogi cal and
rad io metric dat a
UI
Pliocene
3.65 and 2.X Ma
(KlAr da tes
o n basa lts)
Pa leonto logy
G lacial di ssect ion
Up lift of Pecten Cong lomerate to 220-250 mete rs above
sea leve l fro m a pa lcodepth of < 50 meter s
G lac ia lly d issec ted eros io n su rface
Shallow marin e (?Iittora l). cong lo me ra te. sa ndsto ne and s iltstone :
rich ly fossi lifcrous. includi ng. Chlamys anderssoni ( H E:" NIG) . d iatom s.
fo nun inifc ra, rudiol arians. silicoflage llates. sponges. cchinoids,
bryozoans. ostraco ds, barn acles. moll uscs. and hrachiopods.
Ice and/or wat er d issected erosio n sur face
U!
"Submarine ba sa lt flow and inte rca la ted tuffa ceous sed imcnts.
Pyroc lastic tuffs and mar ine tillit e with Chlamys anderssoni ( H ENNIG) .
in basa l l ames Ross Island Volca nic Group at l ames Ross Islan d not
yet recogn ized at Cockb urn Island
l ames Ro ss
Island
Volca nic Gro up
U1
Eoc ene
~
Cong lomerat e
~
Plioce nc
~
Pecten
2J; to 2.0 Ma
(D iato ms)
Rem arks
Litho strat igra phy
Scattered ign eou s
and meta morphi c
erratic »
Pleistocene
155
~
La Mese ta
Form ati on
~
Ice and /or water d issected erosion surface
No ev ide nce for Eocene fossi ls reworked into Pecten Conglome rate
U.j
Lopc z de
Cretaceous
Pa leo nto logy
Bertoda no
Formation
Cre taceous forami ni fcr a and ca lcareo us na nnop la nkto n
reworked into supraj ace nt Pecten Conglo me rate
F ig . 4
Me sozoic (Cre taceo usj -Ccno zoic s tra t ig ra p h ic nome ncl a ture for Cock b urn Isl and.
a few crysta lline frag me nts . Mi cr ofo ss il prep arat ion s co nta in recycled Upper Cretaceous agg luti na ted a nd
planktic fora minifera, a nd ca lcareous nann opl ank ton (G AZDZICKA a nd GAZDZICK I 1994 ). it is a ppa re nt
then , tha t the prove na nce fo r the for ma tion incl udes the roc ks of the Up per Cretaceous Marambi o Group
and th e uppe r Mi oce ne-I owe r Pli ocen e Jam es Ross Isl an d Vol cani c Gro up. No sed ime nts a nd micr o fossil s
appear to have been recy cle d int o the Pecten Cong lo me ra te from Pal eogen e se d ime nts suc h as the Eoce ne
La M eseta Forma tion. T he presen ce o f Jam es Ross Isl and Volca nic Group roc ks a nd M ar amb io Group
mi cro fo ss ils impli es th at these roc ks we re above sea le vel , erode d, and trans port ed to the coas tline at
which the Pecten Cong lomerate was bein g dep osit ed .
AGE A SS IGN MENTS IN EA RL Y LI T ER AT UR E
Defin ition s of th e Mi occn e , Pl ioccn c and Ple istocen e e poc hs and th e ir temporal va lues have evolve d
over the past nin et y yea rs . T he ages assigned by th e p ion eer geo log ists in the area mu st be interpreted
with ea rly 20 th ce ntury stratigraph ic nom en cl ature in mind . In the first decad e of the century the Pleistoce ne and Pl ioc en e were th ou ght to have re presente d g lacial a nd pre-gl acial cl im atic co nd itio ns resp ect ively. ANDERSSO N ( 1906) int erpreted th e Pecten Co ng lo merate macro fuuna as indi cative of non-gl aci al
co ndi tio ns and, mu st , ther efore, have bee n Pli occn e in age . His age det erm inati on was also based on
co rre la tio n of the mac ro fossiI fa una w ith the Parana - Ca pe Fai rweathe r Bed s in Patagoni a (South A me rica) .
Slig htly lat er, BUCKMAN ( 19 10) pr op osed a Ple istocen e age for the Pecten Co ng lome rate based o n hi s
interpret ati on o f thr ee spec ies of brachi opod s. So firm was A NDERSSON'S beli ef that the Pecten Co ng lomera te was a non -gl acial dep o sit th at he wrote in B UCKMAN (1910, p. 4 3), " tha t eve n the beginnin g of th e
g lac iation o f th ese tract s fall s into (i.e. withi n) the Q uaternary pe riod ." Despi te BUCKMAN'S s uggested age
revision and A NDERSSON'S a ppa re nt acce pta nce , WILCKENS ( 1924), SO(H- R YE N ( 1952) , and more recent
aut ho rs co ntinued to ado pt a Pl iocen e age for the dep os it. In co ntrast, HENNI G ( 19 10) and FAIRBR IDGE
( 1952) opted fo r a Ple istocen e age, a nd HARRI NGTON ( 1965) dipl om ati call y refe red to th e age as ea rly
Plei st ocen e or late Pli ocen e. Th e non -gl ac ial/pre-gl uc ial argu me nt no lon ger applies as it is now realized
that the cryosp heric history of West a nd Eas t Anta rctica ex te nds to at least the late Eocene a nd the Pecten
156
ANDRZEJ GAZ DZICKI and PETE R- NOEL WE BB
Fig . 5
A sa mple fro m the Pecten C o ng lo me rate (AG I s ite ) with we ll pre served spe c imens
of Chlamvs andersso ni ( H iO NN I(; . 1(10 ). Sca le bar is 3 c m lo ng.
Cong lo me ra te re prese nts but o ne of a number o f degl aci al or int ergl aci al e ve nts. Thu s, th e Pli occn c age
ass u med b y m an y for a lmost a ce n tury was, to a deg ree , a for tu ito us cho ice , part icul arl y as the lo wer a nd
uppe r limits of th c Pli o ccn c E poc h ha ve c ha nged m ar kedl y in the co urse of th is ce ntury. In si m ilar ve in,
th e middl e -upper M iocene age given by A NDER SSON ( 1906) to th e Ro ss Isl an d Forma tio n (Ja mcs Ro ss
Island Volc ani c Gro up of A Du: 19 53 ) becau se th ey were inte rp o se d bet wee n Lowe r M iocen e ( now rega rde d
as Eoce ne) se d imc nts and th e Pli oc en e Pecten Co ng lo mcratc was a lso in pa rt correct.
AGE ADOPT ED H ER E
Radi ometric da tes documented above a llow th e ass ig nmc nt o f an o ldest agc for th e Pecten Cong lo me ra te of 3.65 Ma . HARw()()D ( 1986) assi g ncd the marine d iato m flora to 2.8-2 .0 M a. T he fora m inife rid
An nnoe lphidiella antarctica CONATO et SH; RE ( = Trochoelphidiella onyxl WE IlIl) occ urs in both thc Pect en
Cong lo merate a nd at a number of ot hcr sites in the McM urdo So und area ( ISIIM AN a nd W EBB 1988). In
DVD P drillhol e 10, Tay lo r Valley, ISIIMAN an d RIECK ( 1992) emp loyed mag nctost ra tig raphic a nd biostrati gra phic data to co nst ra in the age of the Anunoelphidi ella autarctica Zo ne to be tween 3.4 and 3.7 Ma .
Annno elphidiella antarctica an d Chlam vs and erssoni also occu r in the Sca llo p Hill Fo rm atio n of northern
Br o wn Peninsula , so uthe rn M c Murdo Sou nd , be twee n volca n ic ro cks d at ed at ot he r loc ali tie s o n Brow n
Pen in sula as 2.25 a nd 2.2 M a (SPEDEN 1962; EGGER S 1979; L Ee KI E and WEIlIl 1979). Volcan ic boul ders
coll ect ed wi thin th e format ion p ro vide d da tes of 2.58 a nd 2.62 M a (WEBIl and A NDREAs EN 1986). Th e
latt er autho rs int erpret ed th e Sca llo p Hill Forma tio n as be in g yo ung er th an th e age of the yo u ngest da te d
basalt bould er , i.e. 2.58 M a o r lat e Plio cen e . Earlier, Wuw ( 1972, 1974) s ugges ted an ag e between 2.5
FORAM INIFERA FROM THE PECTEN CONGLOMERATE
157
Fig. 6
A sample from the Pecten Conglomerate (AG I site) with fragments of Chlamys anderssoni (HENNIG)
and basaltic clasts from the l ames Ross Island Volcanic Group. Scale bar is 3 cm long.
and 3.7 Ma, fo r th e Pecten Gravel s of Wri ght Vall ey based o n a sur m ise d re latio ns h ip to dated volcani cs
in W right Vall ey. In a mor e recent es tima tio n for the age of th e Pecten Gravel s, PRENTICE et al. ( 1993)
calculat ed a X7Sr/X6S r ratio -based age of 5+/- 1 Ma from Chlamys tuftsensis, a spe cies w h ich eo-occ urs
with Ammo elpdiella antarctica CONATO et S EGR E, 1974 (= Trochoelphidiella onyxi W EBB, 1974) in th e
Pro sp ect Mesa G rave ls (= Pecten Gravels) o f ce ntra l Wrig ht Valley.
In sum ma ry, radi om etri c and paleontologic ev ide nce from Co ckburn Island indi cat es that the Pecten
Con glom erat e was dep osited du rin g the lat e Pliocen e and possibl y during a late Pli ocen e high stand of sea
level. Th e formati on may to be assoc iated with o ne of two sea level high stand cy cles bet ween 2.4 and 3.6
Ma (HAQ et al. 1987 ). It may be coeva l with eit he r the Scall op Hill Formati on « 2.58 Ma) of Brown Peninsul a
or the Ammo elphidiella anta rctica Zo ne o f DVDP 10 in Taylor Valley (3 .4 to 3.7 M a). Ammoelphidiella
antarctica a ppea rs to be confi ned to the Pliocen e (W EBB 1988), but, as a sha llo w water benthic orga nism it
may ha ve mad e up to three or fo ur appea ra nce s during Pliocen e tran sgr ession s in A ntarc tica , ther eby
pro vidin g an intermittent bio strati gr aphi c record .
FORAMINIFERA
INTRODU CTOR Y R EMARK S
We would like to have inc orp o rated Rich ard HOLLAND'S primary co llec tio n in the pre sent study, but were
unsuccessful in atte mpts to locate it. Professor Valdar JAANUSSON rep orted that it does not appear to be in
the co llec tio ns of the Naturhistori ska Rik smuseet , Stockholm. Or. J. E. WIIITTAKER, Head of Mi cropal eont ology, Briti sh Mu seum of Natural Hi stor y, London , was unabl e to locate the co llec tio n in eithe r the BMNH
158
ANDRZEJ GAZDZICKI and PETER-NOEL WEBB
or British Geol ogic al Sur vey, Nottin gh am . Dr. Whittaker not ed th at Rich ard HOLLAND lived for a tim e in
London and th at some of his mi cr opaleontologi cal library w as donated to th e BMNH in 1946. HOLLAND
wo rked ex tens ive ly with H.W. B URROWS, an arc hitec t, w ho devot ed his lei sure tim e to study ing fossil s,
including foram inifera. We ha ve been unabl e to es ta blis h how and w hy the co llec tio n of Cockbum Island
fora m inife ra made its way from Stoc kho lm to Richard HOLLAND. It is po ssibl e th at H.W. BURROWS was
so me how involved in arra ng ing for HOLLAND to carry out thi s study . Fred eri ck C1IAI'MAN investiga ted the
Qu aternary for amini fera from Ca pe Barne-Cape Ro yd s, Ro ss Island, Antarc tica abo ut thi s tim e and it is a lso
possibl e that he wa s in so me wa y involve d (C HAPM AN 1916a ; W ARD and W EBB 1986 ).
HOLLAND (1910) based his study of Pecten Cong lo me ra te fora m ini fe ra o n a sing le sa m ple (Swed is h
South Pol ar Ex pe d itio n Loc ality No. 12). HOLLAND rece ive d a co llectio n of foramin ifer s a nd ap pare nt ly
did not work wi th th e origi na l se di ment. He records tha t th e number of tests subm itted to him tot aled 304 .
We do not know w ho prepared th e co llec tio n, but g ive n the state of m ic ro sc op y at th e tim e and th e re sults
we have o bta ine d, th e un kn o wn c ura tor pro vided a reasonabl y re prese ntative collectio n to HOLLAND.
HOLLAND (19 10) ident ified , described a nd illu st rat ed 8 ge nera and 11 spec ies. He not ed th at pre ser vati on
varied fro m exce lle nt to very poor and o bserved (p. 4 ), "t he spec ime ns are rathe r poorl y grown and seem
to indi c ate starved or brackish wa ter co ndi tio ns" . O nly ca lcareo us benth ic taxa were reco gn ized . HOLLAND
( 1910) o bserved th at five -s ix ths (or 83 percent) of the fauna was ma de up of Cassidulina erassa D' O RI3 IGN Y. As hi s sta nda rd re feren ces, he used the th e n fa sh ion abl e papers by B RADY, D'ORBIG NY, JONES,
PARKER a nd BRADY, LAM ARCK, Li N N I~, DE MONTAGU, PARKER a nd JONES, T ERQUEM , W ALKER, and W ALKER
and Bo ys . T h is lit eratu re em phasized Recent deep an d sha llow water fa unas, as well as faun as fro m the
yo unge r se d ime nts of th e Pari s Basin . Much of the information pro vided in HOLLAND ( 19 10) is repeat ed
by H ENNI G ( 19 10) who adde d ad ditio na l in format ion o n ecologic a l di str ibuti on for so me spe c ies. M ost of
H ENNI G' S co m me nts emphas ized bracki sh a nd estuari ne e nv iro nme nts as th e lik el y env iro nme nt under
w hic h the Pecten Cong lo merate w as dep os ited.
SAMPLE MATE R IA L USE D I N T HE PR ES E NT STU DY
O ur review of the forami nifera is based on co llect io ns made at the typ e loc al ity on Cock burn Isl and
in Marc h 1982 (Pete r-N. WERB) a nd J anu ar y 19 8 8 (And rzej G AZDZICK I). A piec e of J . G un nar A NDERSSON 'S orig ina l sa mp le fro m Loca lity No. 12 was o btained from the Naturhis to riska Riksmu seet, S tockholm in 198 7 a nd the fa u na ex tracted fro m this sa m p le is inco rporated in the resu lts prese nted here . We
refer to this sa m ple and its assemblage as S PE 12. S ix of the sa mp les co llected by the a uthors at Cockburn
Isl an d are a lso used her e and are re fe rred to as AG I- A G 3, and PNW 12-PNW 14 (Text-figs 2-3). O ur
samp les were co llecte d at a va ilable o utcro ps (see Text- figs 2-3) a nd no strat ig ra ph ic orde r is im plied .
O riginal sa mple s ize of AG a nd PN W sam ples is approximately two ki lograms. M o re th a n 160 0 te st s
extracted from these seven sa mples were used in the present stu dy .
S YSTE MA TI C NOTES
Th e c lass ifica tio n of Orde r Fora mi nife rida used he re is that o f LOERLl CH a nd T APPAN ( 1988). Fa m ily,
subfam ily a nd generic nom en cl aure and a uthors a nd da te s of publicat io n are pro vided bel o w, bu t not c ite d
in the re fer en ces. T h is information is re ad il y ava ilab le in LOEBLl ClI and T APPAN ( 1988). S yste mati c note s
pro vid ed bel o w are accom pa nie d by a list in g of o ur re visi on s to HOLLAND' S ge neric a nd species det ermi nation s (Ta b le I ). In Tabl e 2, we show taxa rec orded in the seve n sam ples exam ine d . Inform ati on include s
the number s of test s rec o ver ed , a tot al count o f a ll tes ts in e ac h sam ple , a nd for th e more com m o n taxa,
the per centage co ntributio n to the assem b lage. Repre sentati ve co llec tio ns are lod ged in th e In st itute of
Pal eobi ol og y, Poli sh Acade my of Sciences , War szaw a under the ca ta log ue numbe r Z PAL EXXXV III ; a nd
the U.S. Na tio nal Mu seum (S m irhso nia n), Wash ingt on , D. e.
Fam ily SpiriIIinidae R EUSS et FRITSCH, 1861
Genu s Patellin a WILLlAM SON, 185 8
Patellina corruga ta WILLlAM SON, 185 8
1858. Patellina co rrugate
1986. Patellin a corru gate
Remarks. -
WIL Ll A M SO N .
p. 46. pI. 3: 86-89 .
and W EIl Il . p. 194. pI. 5: 13-1 4 .
WILI.I A M SO N; W A RD
A sing le robu st spec ime n in PNW 13 .
159
FO RA MIN IFERA FROM THE PECTEN CONG LOMERATE
Tab le I
S y stematic r ev i si on of foram i n ifera l taxa from t he 1901 -1 90 3 Swed i sh So u t h Polar Ex p edi t i o n sam p le SPE 12
de scribed and illu st r ated by H <1I.I.A NIl ( 19 I 0 ).
HOI.I .t\ NIl (1910 )
This In vesti gation
I ~ ~~ ~~~~~ --- ~~~ ~~
~~~
~
~/ 1' l/ill a co r ru gata WII .I.I A MSON
_
~'gofo rl/ as ill ii OI ,\I' ~ l A N 1'1 PARR
~\'rg o 1'/ollgal a ( ll 'ORIl I(; NY I _
hi/(}( ' u /illa~ _ _ _
_ __
J Jiloculill a r i ll g1'll s (LA M A RCK_)
_
Jl-B_i _
/O_l _
·U_/I_
·ll a 1'/ollga /{l ll 'O IW I(; N-,,-- _
_
__
Miliolina g ra ll~( T E I{(.) tll ~
_ _
_
Lenticul ina gib/m (ll 'ORIl ((; NY )
Criste lla ria gibba ll 'OR Il IGN Y
Pseudon odosa ria sp .
Polymorphina gUl/ a (Il ' ORIl I( ;N Y)
er.
er.
Fissurina er.
F issurilla
s1'lll illl (//g i ll a l a (R ELJ SS)
Fissur illa
/a1'l' igal a R ELJ SS_'
quad rata
_
_
t-
( WII. I. I /\ ~ l S 01" l_
Do /i li a g /o!Josa ( MONTAl , lI)
Cass idulina
crassa ll 'ORIl I( ;N Y
- - --
---
-
- -- - -- - -
-
- - - -- - - - - -
-
Lag1'l la g /obo sa ( M ONTAGLJ ) _ _
_
f-- -
-
f-- -
Cassi duliua crassa D' O RIl IGN Y
--
Cassi du /i ll o ides p a r ker iall us ( BR AIlY)
Globocassidulina sub glob osa (B RAIl Y )
A ngulo ger ina angu losa (W II. L1A MSON)
Fursenk oina cl'. ea rland i (PARR)
t./JiSIOlllill 1'l/a l'il r1'a P A RKER
_
Discorb ill 1'l/a sp,
-
-
-
-
-
- -
-
- -- - -
-
- --
-
-
-
-
-
-
-
-
-
- --
-
- -- -- --
- -- -- - - - - 11
refu lge ns (Il E M ONTH JRT )
Cibicides refu lgens DE M ONTI' ORT
Truncatulina
C ib ic id1's /ob alil/us ( W A I.K U { 1'1 J ACOfl )
Truncatulina lobatula ( W AI.KE R)
(n o t rec o g ni sed )
Nonionella bra d ii (O IAPM AN)
No nionella cl'. turg ida ( W II.I.I A MSON)
Meloni s sp,
Crib rono nion sp .
A mmoelp hidiella anta rctica CONATO 1'1 S EGRE
Rotalia becca rii (lI NN(n
Family Hauerinidae SCHWAG ER, 1876
Subfa mily Miliolinellinae VELLA, 1957
Ge nus PYIRo DEFR ANCE, 1824
Pyrg o fo rnas ini i CIIA I'MAN et PARR, 1935
(PI. 34: 1- 3)
1884 .
1910.
1935.
1960.
Bil ocul ina rin gens ( LA MARC K ): B RAIl Y, pI. 2: 7 .
Biloculin a ringens ( LA MA RCK ): H OI.I .A NIl, p . 5, p I. I: 5- 8.
Pyrgofornasin ii C II AI'M A N 1'1 PA RR, p . 5.
Pvrg o fo m asi nii C II A PMAN 1'1 PARR : B ARKER . p . 4. pI. 2: 7 .
Remarks. - Large circular sha ped tests. HOLLAND ( 1910) gives a test diam eter range of 0.75 to
2.9 mm. He also ind icates that this species is comm on in SP E 12 althoug h we did not record it in the
re-processed split of the same sample. Six tests in AG 3, where it makes up 3 percent of the asse mblage .
HOLLAND comments on the test shape vari abil ity in his materi al. Som e form s assume an oval shape with
a we ll-ro unded per iphe ry, whil e oth ers ex hibit a more circular form and sharp edge around the final
chamber, as in P. dep ressa (D'ORBI GNY).
Pyrgo elongata (D' ORB IGNY, 1826)
1826. Biloculina elong ata D 'ORIlI(, NY , p . 298, n o . 4 .
1884 . Bilocu lina elongata D ' O RIlI GNY; B RA DY, p . 144, pI. 2: 9.
160
AND RZE J GAZDZIC KI and PET ER -NO EL W EBB
1910 . Biloculina elongata D ' O RBIGN Y; H OLL AND. p. 6. pI. I: 9- 10.
1960 . Pyrgo elongu ta (D 'ORIl IC, NY); B A RKER, p. 4, pI. 2: 9.
Remarks. - No specime ns we re recove red fro m o ur sa m ples . HOLLAND ( 19 10) not ed th at in his
mat eri al th e va ria bi lity o f sha pe incl ude d a trend to w ards th e more c irc ular Pyrgo [o rn asinii CHAPM AN et
PAR R [= Biloculina ringens (LAMA RCK» ).
G enu s Trilocul ina D'OR HIGNY. 1826
Triloculina s p.
1910. Mil iol ina grata
(TEIH)lJEM): H OLL AND,
p. 6. pI. I : 3-4.
Remarks. - HOLLAND (1 910) desc ribed a nd illu st rated a s ing le un -orn am ented sub-tria ng ular rnili oIinellid w ith a di am et er o f 1.75 mm. The ape rture is show n as a short cresce ntic s lit, without a b ifid tooth ,
but perhap s w ith a s ma ll ape rtura l flap . We did not e nco unte r thi s fo rm durin g o ur study. From HOLLAND ' S
de scripti on and illu st rati ons th e s pecimen is prob abl y best pl aced in the ge nus Triloculina until co mpa ra ble
mate ri al is reco vered .
Fa m ily Nodosariidae EIIRENB ER G, 1838
G enu s Lenticul ina LAMARCK, 1804
Lenti cul ina gib ba (D'ORB IG NY , 1839)
(PI. 34: 6)
1839. Criste lla ria gi b/m D·ORIl IGNY . p. 63. pI. 7: 20-2 1.
1884 . Cristellaria gibba D'ORIl IGNY: BR AD Y. pI. 69: 8- 9.
1910. Cristella ria gi bba D'ORIl IGNY ; H O I.I.AND, p. 8. pI. 2: 3.
1960. Len ticul ina gibba (D 'ORB IGN)'): B ARKER . p. 144. pI. 69 : 8- 9.
Remarks . - S pec imens sho w a tenden cy to un coil and resemble Astacolus. R ar e . In add itio n to th e
speci me n illus trated by HOLLAND (19 10) fro m S PE 12 we rec o ver ed o ne specime n in AG 2 a nd o ne in
PNW 13.
Ge n us Pse udonodosaria BOOM GART, 1949
Pseu donodosaria sp .
(PI. 34 : 4- 5)
1910 . Polym o rph ina gu tta
(D 'OR llI<; NY); H O LLAND.
p. 9. pI. I: 11 -1 2.
Remarks . - HOLLAND ( 1910) illu strat ed the sing le spec ime n he had a va ila ble . Th is was g lo bu lar, w ith
a s lig ht spi ne- like pr otuberance at the initial e nd, and a di st inctly radi at e a pe rture . He pl aced thi s w ith th e
pol ym orphine s but ad m itte d being un abl e to d iscern int ernal c ha m be ring . We have si m ilar s ing le large
specimens in AG I an d PN W 13, w ith d istinctive overl a pping nod osar id cham be rs a nd rad iate a pe rtures.
We s ugges t thi s fo rm be placed w ith Pseudon odosa ria sp.
Fa m ily EllipsoIageninidae A . S ILYESTR I, 1923
Ge n us Fissurina REUSS, 1850
Fissurina cr. seminia rgina ta (R r.uss, 1871 )
(PI. 34 : 7)
1871 . Lage na marg inata MO NTAG lJ var. se mimarginata R ElJSS. p. 468 , pI. 4 : 4-6.
1953. Fissu rina semima rginata ( RE lJSS) ; L<lI'IlLlC II and T AI' I'AN. p. 78 . pI. 14 : 3.
1960. Fissu rina sem imarginata (RE lJSS) ; BARKER . p. 122. pI. 59: 19.
Remarks. - Ver y s ma ll, s lig htly com pressed, c ha rac te rize d by a s ing le un- ornamented keel o n th e
lower half o f th e test. A sing le test in PNW 13.
Fissurina
cr.
lae vigata R EUSS, 1850
1884. Lag enu laevigata R H /SS : BR AI))' . pI. 11 4 : 8.
1960. Fissu rina laevigata R ElJSS; B ARKER . p. 236. pI. 11 4 :
8.
Remarks. - Test ve ry sma ll, a lmost sphe rical in o utli ne, s lig htly co m pressed w ith a smooth ex terio r.
A s ing le spec ime n in PNW 13.
FORAMINIFERA FROM THE PECTEN CONGLOMERATE
161
Fissu rina c f. quadrata (W IL LlA MSO N, 1858)
1884. Lagena quad rata ( W IL UA MSON) ; B RAD Y. pI. 59: 16.
1960 . Fissurina quadrata ( W n .I.I A MSo N) var. car inata C II APM A N;
B A RKER.
p. 122, pI. 59 : 16.
Remarks. - Test very small, s ubs pherica l in axia l vie w, c harac te rized by tw o sho rt and un-ornam ented keel s ne ar th e base of th e test. Rar e, three speci me ns in PNW 13.
G enu s Oolin a D'ORBIGNY, 1839
Oolina globosa (MONTAG U, 1803)
1884 . Lagena globosa (MONTA<, U) : B RADY. pl. 56 : 1- 3.
1910 . Lagena glob osa (MONTA<, U): H OI.I .A ND, p. 8, pI. 2: 8-9.
1960 . Oolina globos a ( MONTA<;lJ): B ARKER. p. 11 4. pl . 56 : 1- 3.
Remarks. - Spheri c al in ax ia l vie w. Sli ghtly e lo nga te, ape rture o n sho rt neck . S mooth ex te rio r. Rar e,
but th e m or e c ommon of th e e llipsolagenids in PNW 13.
Family Cassidulinidae D'OR BI GNY, 1839
G enus Cassidulina D'ORBIGNY, 1826
Cassidulina crassa D' ORBIG NY , 1839
(P I. 35: 1- 3)
1839. Cassidulina crassa
1910. Cassi dulina crassa
1960. Cassidulina crassa
pI. 54: 4-5 .
p. 7. pI. 2: 2. 5.
B ARK ER. p. 11 0. pl , 54: 4-5 .
D'ORB I(,NY : B RA D Y.
D'ORB IGNY ; H OLL A ND.
D'ORB I( ;NY ;
Remarks. - HOLLAND ( 1910) recognized th is species as th e dominant for m (83 percent) in th e
mate rial supplied to him fro m s a mple S PE 12. In o ur split of S PE 12 it co ns ti tutes 84 percent of the fauna
and is a lso a do m inan t form in AG I , AG 2, A G 3 a nd PN W 12. It is a rel at ivel y m ino r (5 per c en t)
co ntr ibutor to PNW 13, a n asse m blage we regard as th e le ast m odified (see bel o w ) of o ur collectio ns .
Wh ere Cassidulina crassa is dominant, th e test s are large and pre se rvation ra nges fro m good to decortica ted. It is probabl e th at test s surv ive d rep eat ed tran spo rt , thus e nha nc ing the fin al hi gh pe rcentage
occur re nce . C. crassa is a lso the domin an t spec ies (46 to 67 pe rcent) in the Larsem ann Hill s Pl iocen e
asse m blages (Q u u.rv et al. 1991). As illu st rated by BRADY ( 1884), th e test sha pe ra nges fro m subg lo bular
(us ually the s ma ller for ms) to slig htly compressed (larger for ms). Thi s m ay be a n ex pressio n o f ontogen y
and ge ne ra tio n. This is a co m mo n spec ies in man y pol ar a nd deep wa te r asse m blages. As not ed by BAR KER
( 1960), so me a utho rs ha ve fa vo red th e placement of th e more com pressed and e lo ngate te st s in C. oblonga
Re us s , wh er eas other s favor ed ret ention of th ese in C. crassa . M ARKS ( 195 1) co nfirme d thi s by pl acin g
C. oblonga in sy no no my with C. crassa.
Ge nus Cassidulino ides CUSIIMAN , 1927
Cassidulinoi des parkerianus (BRADY, 1884)
(PI. 35: 4-6)
1884 . Cassidulina parkeriana BR AD )' . pI. 52: 11 -1 6.
196D. Cassidulino ides parkerianus ( B RAD)') : B ARK ER. p. 11 D, pI. 52 : 11 -1 6.
Remarks. - HOLLAND ( 19 10) di d not report this spec ies and we fo und o nly fi ve spec ime ns in th e
sp lit of S PE 12. A fe w s pec ime ns are present in a ll o ur samp les a nd it cons titutes 5.5 per cent of th e
asse mb lage in PN W 12. Q UII TY et al. ( 1991) reports C. c f. park erian us as th e seco nd most com mo n
species afte r Cassidulina crassa D'ORBIGNY in th e Larsernann Hill s Pli ocen e. A t th is latt e r locality it
mak es up to bet ween 18 a nd 33 pe rcent of th e asse m blage.
Ge nus Globocassidulinu VOI.OSIIINOYA, 1960
Globocassidulina subg lobosa ( BRADY, 1881)
(PI. 35: 7)
1884 . Cassidulina sub globosa B RA D)' : B RAD Y, pI. 54: 17.
196D. Cassi dulina subglohosa BRADY : B ARKER. p. 11 2. pl. 54: 17.
1988. Globocassidulin« suhglobosa (BR AD)') : L OEBI.I CII and TAI 'PA N. p. 505 . pI. 557 : 18- 23.
162
AND RZEJ GAZ DZ IC K I and PETER-NO EL W EB B
Remarks. - Tests much smaller than the accomp anying co mpressed and at times slightly uncoiled
Cassi dulina crassa D' ORB IGNY and the elongate and uncoilcd Cassidulino ides parkerianus (BRADY). Tests
of C. sub globosa are tightly enro lled . Most common in AG 2 ( 11 per cent of asse mblage) and best preserved
in PNW 13 .
Fa mily Buliminidae HOFKER, 1951
Ge nus Ang uloge rina C USIII\ IAN, 1927
Ang uloge rina angulosa (W II .L1AI\ISON, 185 8 )
(PI. 34: 8- 10)
1X5X. Uvig eri na angul osa
WII . I.I A ~ l S 0 N .
1XX4 . Uvigcrina angul osa
WI1.I.I A ~l S 0 N : B KA DY.
1960 . Angu logeri ua an gul osa
19 XX. A ng ulog erina an gul osa
p. 67.
pl . 74 : 15-1 6 .
( W II .I.I AM SON) : B A RK ER.
p. 154 . pl . 74 : 15-1 6.
( W II.I . I A~ l S0 N) : L OEBLl CII
and T A I' I'I\ N. p. 5 2X. pl. 574 : 5-9 .
Remarks. - Test triscri al and trian gular throu gh out. Orn am entation consi sts of distinct longitudinal
costae. Not reported by HOLLAND ( 1910) in SPE 12. Rarc. Samples SPE 12, AG 2 and PNW 13 contain
two , three and one spec ime ns respectively.
Famil y Fursenkoinidae LOEBLl CII et T APPAN, 1961
Gcnu s Fursenkoina LOEBLl CII et TAPPAN, 1961
Fursenkoina cr. earlandi (PA RR , 1950)
(PI. 35 : 8-9)
1950 . Bol ivina ea rlandi
PA RR.
p, 33 9. pl . 12 : 16 .
19 X6. Furs enkoina earlandi ( PA KK): W A RD and W EBB. p. 194 . pl . 6 : X.
Remarks. -
Test vcry sma ll, hyalin e a nd we ll preserved . Mod erately comm on in PNW 13 (3 per cent ).
Fa mily Pseudoparrellinidae VOLOSIII OVA. 1952
Genu s Epistomine lla HUSEZI MA et MARUII ASI, 1944
Epistomi nella vitrea PARKER, 195 3
(PI. 35 : 10-11 )
1953. Ep isto minclla vitrea
PA RKER cl
al.. p. 9. pI. 4 : 34 -36.40-4 1.
19 X4. Ep isto minella vitrea PARKER et al.: W A RD and W EBB. p, 190 . pI. 4 : 15-1 6.
1991. Ep isto mi ne lla vitrea
PARK ER
et al .: Quu.rv
1'1 al..
p. 3. pl . I : 12-13 .
Remarks. - Tiny , hyaline, well pr eserved tcsts. Q UII;r y et al . (1991) reports E. vitrea as making up
between 2 and 18 percent of the Lar semann Hill s assemblage . Relatively common in thc split of SPE 12
(3 percent ) and in PNW 13 (6 percent).
Family Discorbinellidae SIGAL, 1952
Genu s Discorbinella C US II MA N et MARTI N, 19 35
Discorbin ella sp.
Remarks. - Plan e -con vex , trochospiral side almos t flat. umbili cal side s lightly co nvex , peripher y
round ed , se ven chamber s in thc last whorl. sutures strongly recu rved on both trochospiral and umbilical
side of test. Rare. Two specime ns in PNW 13 and a single specimen in SPE 12.
Famil y Cibicididae C US III\IAN, 19 27
Gcnu s Cibicides DE MONTFORT, 1808
Cibicides refu lgens DE MONTFORT. 1808
(PI. 36 : 4-6)
1XX4 . Trun ca tulina refulgens (DE M ONT H l RT ) : B RA D Y. pl . 9 2: 7- 9.
1910 . Trun catulina refulgens
1960. Cibicides refu lge ns
( DE M ONT H lRT) : H OI.I .AND.
DE M ONTFORT: B AR KER .
p, 10. pl . 2 : I. 7 .
p. 190 . pl. 92 : 7- 9 .
19 XX. Cibicides refulgcns DE M ONTFORT : L OEBLl CII and T M ' I'A N. p. 5X2. pl . 63 4 : 1- 3.
FO RA M IN IFE RA FROM TH E
P1~'CTl:'N
CONGLOMERATE
163
Remarks. - Much co nfus ion ex ists in the literature as to the distin cti on between Cib icides refu lgens
(DE MONTFORT, 180 8) a nd Cibici des !obaIU!US (WALKER et JACOIl, 1798 ). HOLLAND ( 19 10) recogni zed
both spec ies but illustrated only a test ide ntified as 7 i 'UII CllIlIIiIl1l refu lgens. HOLLANDwrites of C. refulg ens
(p. 10), "T his is but a varie ty of the co mmon Truncatulina lobatula in which the co nvexi ty of the ora l
surface is more pron oun ced and the sutures and periph er al margins of the cha mbers on the abora l surface
are more d istinctly e mphasized". HOI.I .AND's fig ures agree reasonably we ll with LOEIl I.ICII and TAPI'AN'S
( 1988) illu stration of C. reji tlg ells. We recog nize C. rcjulge ns tests that are strong ly piano-con vex, but
note there is co nside rable variat ion in co ncavi ty and co nvex ity on the spiral side . In some tests, lon gitud inal grooves across the spira l side indicate attac hme nt to spo nge spicules or other linear objec ts. C.
refulgens is present in all sa mples , and the dom inant spec ies in PNW 13 (33 perce nt).
Cibicide s lobutulus (WALKER
(pI. 36: 1- 3)
el
JACOB, 1798)
I79li. Nautilus lohu tul us W ,\LKIOR c l J ACO B. p, 642 . pl, 14: 36 .
Ilili4. Truncatuli na lobatu! a (W ,\ L KIO R c l J,\ ("OB) : B RA Il Y . pl. 92 : 10. pl. 93: I. 4-5 .
1910 . T run catnlina lobatula ( W A LKER c l J A(" O B ) : H OLJ ,/\ NIl. p. 10.
Il)60. Cibicidcs /O/WIII/II S ( W ,\ LK I 'R c l J A("O B ) : B ,\ I<K IO R. pp . 190 and 192. pl. 92 : 10. pl. 93: I. 4-5 .
Remarks. - Following the discussion of C. re fu lgens, above, we appl y the name C. lobatulus to tests
that are piano-to concavo-con vex, and in which the co nvex ity of the umbili cal side is much lower than for
C. refu lgens. C. lob atulu s tends to spread laterall y and may assume irregular shapes, this bein g attributedto
attachment strateg ies. The sutures, chambering and porosity on the spiral side may not be as well developed
as in C. refu lgens, aga in this probably resulting from the effects o f attac hment. We stress though, that the
differences between of C. lobatulus and C. refulge ns are proba bly induced ecophe notypica lly.
Fa mily Nonionidac SClIUJ:rZE, 1854
Ge nus No nio nella C USlIl\lAN, 19 26
Nonione lla bradii (C1 IAI'I\IAN, 191 6)
(PI. 36 : 7- 8)
Ilili4. Nou ionina scapha (FIClITIOLL et M OLL): BR AIl Y. pl. 109: 16.
1916b. No nionina scapha var. bradii C1 IA I'I\ I A r\ . p. 7 1. pl. 5: 4 2.
1960. Noni ouella bradii (C II A I' I\I A r\ ) : B ,\ RK IO R. p. 224 . pl. 109: 16.
Remarks. -
Co mmo n only in PNW 13 ( 12 percen t).
No nione lla cr. turgida (WILI.IAMSO N, 185 8)
Ilili4. Nou ionina turg ida WJI .LI A I\I S0 N : B R,\ Il Y . pI. 109: 17-1 9.
1960. No uionella turgida ( W II .L IAI\ I S0 N) : B A RKI ; R. p. 224 . pl. 109: 17-1 9.
Remarks. -
Sin gle spec ime n in PNW 13.
Ge nus Me lo nis DE MONTFo RT, 180 8
Melonis sp.
(PI. 37 : 1- 2)
Remarks, - Eight moderately inflated cha mbers in final whorl, broadl y rounded pe ripher y, bi-urn bilicate, umb ilical depression , sha llow, test wall hyalin e and perforate. Three spec ime ns in PNW 13 and
one in SPE 12.
Ge nus Cri brononion TIIALl\l ANN, 194 7
Cribrono nion sp.
(PI. 37 : 3-4)
Remarks. - Test moderately inflated in apertura l view, s ix cha mbers in final who rl. sutures s lightly
depressed. Row s of sutural pores ex te nd from the umbili cu s o n both s ides and aro und periphery. Umbilical
areas pustul ose. Sin gle spec ime ns in PNW 13 and S PE 12.
164
ANDRZEJ GAZDZICKI and PETER-NOEL WEBB
Family Elphidiidae G ALLOWAY, 193 3
G enus Ammoe lphid iella CONATO et S EGRE, 1974
Ammoe lphidiella anta rctica CONATO et S EGR E, 197 4
(P I. 37: 5-7; PI. 38 : 1-10 ; Te xt -fig . 7a-d)
1910 . Rotalia beccarii
1974. Ammoe lphidiella
( LI N N I~); H OI.I .AND.
1I11111rcliclI CONATO
p. 11, pI. 2: 11 -1 2.
et SEC, RE. p. 12.
1974 . Trochoelphidiella onyxi WEIlIl. p. 196. tex t-figs 4-6. pis 1- 5.
1988. Ammoe lphidiella antarctica CO NATO et SHiRE; L OEIlI.IC II and T APPAN. p. 678 . p I. 794: 8- 17.
1991. Ammoelphidiella antarctica CO NATO et SHiRE; Q UII: r y er 1I1.• p. 5. pI. I : 21.
Remarks. - HOLLAND ( 19 10) not ed th at thi s s pe c ies was quite com mo n in his split of S PE 12. Thi s
taxon cons titutes abo ut 19 percent of th e tot al spec ime ns ex trac te d fro m the Pecten Con gl omerate. Test s
in PNW 13 are we ll preserved a nd include a w ide ran ge o f tes t s izes. Both ge ne ra t io ns are present but
th e sma lle r me gal o spher ic test s dominate. The few -ch amber ed ju venil e form s not ed by W EBB ( 19 74) in
th e Pli oc en e Pecten Grave ls o f Wri ght Valley ar e not present in th e Pecten Co ng lo me ra te . Te st s pr es ent
Fig . 7
Atnmoelphidiella 1I11111 r clica OIN ATO er SHiRE. 1974
a - highl y co nvex sp iral side . troc hos pira l-streptos pi ra l coi ling we ll de velo ped . sample AG I. ZPA L F.XXXY IIII19. x I 10;
b - broke n test. side vie w. very thick wa ll. sa mple AG I. ZPA L F.XXX YIII/20. x 80; c - brok en test viewed fro m umbilic al
side. ci rcular whor l of initial cha mbers at ce nte r, very thi ck test wa ll and sutures . sample AG I. ZPAL F.XX XYIII/2 1. x 75;
d - bro ke n test from umb ilical side . sample AG 3. ZPAL F.XXXYIII/22. x 75.
FORA M IN IFE RA FRO M Til E !'I:'CTI:'N CONG LO ME RATE
165
in AG 1- 3, PNW 12 and S PE 12 are mostl y th e larger , mor e infl ated and s ubs phe rica l micr osph eri c
ge ne ratio n. We suggest th at the large, rugged , mat rix-fill ed a nd o fte n poorl y preser ved test s w hic h make
a maj o r co ntributio n to sa m ples AG 1- 3, PNW 12 and S PE 12, hav e been s ize -sorte d and se lec tive ly
co nce ntrated . Thi s spec ies appea rs to be a n exce lle nt Pli ocen e ind e x. A pa rt fro m its occ urre nce in th e
Pecten Co ng lo me ra te , it is a lso found in the Pli ocen e Larsemann Hill s asse mb lages ( Q UIITY et al. 1991 ),
and in a num ber of o utcrops a nd drillhol es in the Wrig ht a nd Taylo r Valleys a nd so uthe rn McMurdo Sound
reg io n (WEIlB 1974, 19S8: EG(iERS 1979: ISIII\I AN a nd W EIlIl 1985: and ISIIMAN and RIECK 1992).
C O M ME NTS O N TH E FOR AMINI F ER AL ASSEM B LAGES
Nin eteen ge nera and twent y-four species are document ed , a two-fold incr ea se ove r the d iver sit y docume nted by HOLLAND ( 1910) see Ta ble I and Pis 34-38. Th e most co mmo n ta xa are members o f the famili es
Cass id ulinidae . C ibicid idac, and Elphidiidae (Ta ble 2) . In most instances. five spec ies co nstitute nin et y per
ce nt o f eac h assembl age in term s o f test abundance . Th ese taxa are : Cass idulina crassa, Globocassidulina
subglobosa. Cassidulinoides parkerianus. Cibici des lobatulus, and Ammoelphidic llu ant arctica (Table 2).
Sa m ple PNW 13 pro vides the hi gh est di versit y at twent y on e s pe cies (Ta ble 2 ). Eig htee n s pecies ar e
present in S PE 12. Di ver sit y total s in the othe r five sa m ples ran ges between 2 and 9 spec ies. Althou gh
o nly thr ee o f the asse m b lage counts att ain ed th e ideal figure o f 300 test s, we beli e ve we ha ve es ta blishe d
an app ro xim at e accountin g for eac h assembl age a nd ha ve prob abl y iso lated 90 per cent o r more of th e
tot al Pecten Cong lo me rate for aminifer fauna .
We ha ve uti lized W ALTON'S ( 1964) per centage dorni nan ce/ sp eci es number sc he me to co m pare , contrast
and exp lain asse m blages (Tex t-fig . 8). Th ese fact ors we re o rig ina lly used as a meth od for di st ingui shing
ba thy met ric di st ribut ion of sha llo w wa te r fora m in ife ra l asse m blages in the Gul f of Mex ico . Thi s is also
a use ful method for showi ng cl us te ri ng (si mi la rity) a nd scatte r (d iss imilarity) a mo ng rel at ed asse m b lages.
O ur experie nce has been that inn e r she lf-s ha llow wa te r biofac ies are most pron e to reor gani zati on .
Accordi ng to WAITON's ( 1964 ) plot, natural asse mb lages ob tai ned alo ng a sha llow water to deep er wate r
o uter s he lf tran sect sho uld c lus te r a lo ng a high pe rcen tage do mina nce - low spec ies to lo w percentage
dominan ce-h igh species num be r c urve or fie ld . Departu re fro m thi s c urve o r fie ld mi gh t be tak en to
indi cate restructurin g of the death asse mblage by ph ysi cal recyc ling . s ize so rting, rem o val of taxa to deep er
wa te r. and se lec tive destruction o f spec ies.
In the case of the Pecten Cong lome rate m icrof uuna s, we were able to plot o nly s ix asse m blages, bu t
eve n fro m thi s s ma ll numbe r a w ide de g ree o f scatte r is appa re nt (Tex t- fig . S). A ltho ug h natural local
biot op e differenti ati on in litt or al -sublittoral e nv iro nme nta l se tt ings might ex p lai n th e scatter, we beli e ve
that ph ysi cal restructuring und er cond ition s o f high e ne rgy wa te r tu rbati on is a mor e lik el y mech ani sm .
PNW 13 is the rich est asse mb lage spec ies-w ise. conta ins a w ide ran ge of test sizes , and pr eservati on is
ge ne ra lly go od. Ta xa such as th e troch ospi ral Anunoe lphidiella anta rctica ex hibit a more eq ua lly balanced
proporti on of ge ne ratio ns, o ntoge ne tic stages, and test s izes. PNW 13 is int erpret ed as a rel ati vel y compl et e
death assemblage or " po pulat io n" . A ll o the r assemblages are o f lo wer di ver sit y. di splay a high er percentage d om inance value for the most co m mo n s pec ies and di splay poor preservati on ove ra ll. In asse mb lage
PNW 12, for exam ple. tes ts are ve ry lar ge, a re highl y worn or fractured , and a re commonl y in fill ed with
red -st ain ed sed ime nt or seco nda ry ca lcite . Fragil e fina l c ha m be rs a re o fte n mi ssin g . Clearly. these are
remnant asse m blages that ha ve been subje c t to multipl e rec yclin g in high e ne rgy condi tio ns. Fo r thi s
reaso n the dominant or obv io us genera suc h as Pvrg o. Cassidulina , Cassidulinoides, Cibicides a nd
An nnoelphidiella are re lati vel y la rge. A ltho ug h hi sto ric sa mp le S PE 12. part of w h ich was studie d by
HOLl.AND ( 1910). has a rel ati vel y high di vers ity of 18 spec ies . it a lso ex h ibits a ve ry high per cent age fo r
the most dominant species (84 percen t fo r Cassidulina crassai and plot s we ll o uts ide the ge nera l clust er
for all o ther sa mp les (Text -fig. 8). Most tes ts in this sa m ple a re severe ly a bra de d and broke n, test s are
in-filled w ith se d iment. a nd are iron -st ain ed. Test s are mostl y la rge a nd ha ve probabl y been subjec ted to
rep eat ed re work ing a nd s ize so rt ing . It is probabl e. the n, th at the high s pec ies di versit y in this sa m ple
resulted fro m th e ph ysical agg regatio n of a few lar ge a nd rob ust test s of suc h ta xa as Pyrgo [o rnasinii,
Pyrg o elongata, Triloculina sp .. Lenticulina g ibba, a nd Pseudonodosa ria sp. Domin an ce/ sp ec ies number
data from W EIlB ( 1974) a nd Q UII T Y et al. ( 199 1) a re a lso plotted in Te xt-fi g . 8. Th ese sho w the we ll-prese rve d Pro sp ect Mesa (= Pecten G rave ls) asse mb lage (WEIlIl 1974 ) from Wri ght Vall e y to lie cl osest
to PNW 13. Th e Larscmann Hill s assembl ages c lus te r reason abl y we ll but may a lso ha ve been subject to
so me post -mortem re- organi zati on. Th e contributio n o f foraminiferal asse m blages to pal eoec ol og y and
pal eoclimat e is dis cu ssed bel ow.
166
ANDRZEJ GAZDZICKI and PETER-NOEL WEBH
Tabl e 2
Foraminiferal content of se ven sa mples from the Pect en Co ng lomerate, Cockburn Island . Occurrenc es noted in SPE 12,
a sa mple collect ed by J.G. ANDERSSON at Swedi sh South Po lar Exped ition Locality 12 (see Te xt-figs 2-3 ) are based mostly
on our processin g of additional materia ls from the original samp le. Occurrence s repr esent ed under SP E 12 as I * indicates
that a ta xon was noted by HOLLAND ( 1910 ), usua lly one or o nly a few tests, but was not recovered in re-pro cessing of a split
of SP E 12 in the co urse of the present investigati on . Figures represent test count s, and figur es placed in parenth eses ind icate
percentage contr ibut ion o f a speci fic taxon to an asse mblage . Samp les prefi xed by AG co llected by A. GAZDZIC KI; PNW by
P.-N . WEBB . Fossil material other than foraminifera enco untered in micr ofossil preparation s is also summarized.
Ge nus / Species
SPE 12
WILLl A ~l S0 N
Patellina co rrugate
Pvrgo fo rnasinii
C II A P~ l A N
-
et PARR
Py rgo e/ollga l ll D 'O R B I ( ~ _
-
_
--
AG I
-- ~
1*
- -
-
-
- ---
I
-
-
---
1*
Trilocu lina sp.
- - - --
_
- -
I
6 (3%)
--
-
PNW 12 PNW 13 PNW 14
AG 3
--
-
5 (3 %)
-
_
AG 2
-
-
-
-
-
-
- -
,- -
-
-
-
-
- -
- - j - - --
-t---
1*
L ellliclI/illll g i hha ( D ' OR B I(;~ __
P.I'e lldOllodoSll r ia sp_
. _
-
- - --
1*
----
-
-
-
- -- -
I*
-
-
Fissurina cl'. .I'elll illlllrgilllllll (RElISS)
- - - --
\ --
-
I
----
-
-
-
--
- , ---
- -j---
-
-
I
- +- -
- -f---
2
-
-
-
- I - - --
I
- -
-
Fi ssurina cf. laevi gata REI/ss
I
---
-
-e--- -
-
-
3
-
- -- -- - -
I
1*
I
- 1- -
- -1
5
334 (X4% ) 62 (39%)
t-- -
Cassidulinoides parkerianu s (B RADY)
G/o!J oca .l'.I'idu/illa .I'lI !Jg /o!Jo.\'(/ (BRAD Y)
--
5(1.3 %)
6( 4% )
7 (I. X%)
7 (4 %)
- I-
39 ( 11% )
13 (4.5% )
- - - -
Allgll/ogerillll allgll /oslI (WII.L1 AM SON)
2
- - - - -- - -+-- - - -
-
3 (1 %)
1-
j - --
-
---j
1
Fursenk oina cl'. eur landi (PAR R)
10 (3 %)
I I (2.X%)
t .iJiSIOlllillel_Ii_1I'i l rell P,_
\ RKER
- - - -- - - - I-
Discor!Jill ella sp.
-
-t- - -- - -t-- - - - - \- -
-
--'-
C ihicid es refu lge ns DE MONTFORT
If-- ----~-"-------- - Cib icides /o!JlI l lI llI.I' ( W A LK I ;R ~ A COB)
- - I- -
12 (7%)
-
9 (2.5%)
+- ---'.'"
+-
25 ( 12% )
- - - --
1- _
I
- -
7 (3% )
64 (41 %)
I
22 (6% )
157
IX
7
9
6
x
x
x
x
x
-
-
1-
-
-
_I
_
37 (12% )
34 ( 15%)
396
_
1
99 (33%)
-
-
Speci e s / a s s e mb l a g e
-
6(3 %) __12( 4% ) _
_
I
19 (5% )
-
-+-_ _2_ _
+-
6 ( 1.5% )
Nonione lla br adii (C IIAI' MANI
-- -- - 1-
18 (6% )
-
X4 (2X% )
-
-
I
- - - -
22 1
303
2
8
21
2
-
- -- , - - -
- -
O ther fossil material:
Recyc led C retaceo us ca lcareous
nannoplankton
-
- --
-
-
-
-
-f-- -
-
Recyc led C retaceous foraminifera
-
-- -
- -
x
----
S ilicoflage llates
x
Diatom s
x
r---- -
x
- I- - -
Radiolaria
-
Sponge spicules
x
x
Mo lluscan debris
x
x
x
Ostrac od s
Echino id spine s and plates
-
X
1 - - -- - - - - -
~y o z o a n s
- r- -
-
- --
-
-
x
-
-
-
x
x
1-- -- -1 - - - - +- - - x
x
x
--
-
-
x
x
x
-
x
x
-
x
-
x
1--
X
x
-
-
X
x
x
-
-
-
-
-
167
FORAMINIFERA FROM THE PECTEN CONGLOMERATE
C O M PA R IS O N OF TH E P E C T EN CO N G L O MERA TE FO RA M I N IFE RA L A S S EMBLA G ES
WITH O T HE R A NTA RCT IC PLI O C EN E ASSE M B LAGES
Th e Coc kburn Isl an d a nd Larsemann Hill s s uccessio ns p robabl y ex iste d o n bay-i ndented coas tlines,
w hereas Wr ig ht Valley was the s ite of a fj o rd . Sed iments at th e three localiti e s include fi ne to coarseg ra ine d sa nds (sands to nes) , pebbl e to boulder cong lo merates, a nd dia mic ti tes . Each successio n is o nly a
few meters thi ck a nd probabl y rep resents eros io na l remnant s. The foraminifera are int erpreted as indicati ve
of sha llow wat er ma rin e inter gl aci al o r d egl ac ial co nd itio ns associ ated w ith period s o f hi gh sta nds of se a
le vel. S pec ies number pe r assembl ag e at these th ree w idel y se pa ra ted localiti e s is less th an 2 1 (Tex t-fig .
8) and in eac h in st an ce th e fo ur mo st d ominant taxa make up 90 per cent o f th e asse m blage. A ll taxa
pre sen t are mem ber s o f ca lca reo us benth ic fa mi lies . Ne ithe r agg luti na te d no r plan ktic ta xa we re rec o ve red
at any o f the sites .
Annnoelphidiella antarctica CO NATO et SEC/RE, 1974 ( = Trocho elphidie lla onxyi WEBB, 1974 ) is common to a ll th ree reg ion s menti on ed above. Th is large a nd d istin cti ve spec ies appears to be a w ides pread
and use ful Pl iocen e ins hore be nth ic inde x in A ntarc tic basin s. Ammo elphidiella antarctica is th e d omi nant
s pec ies (58 percen t) in th e we ll pr eserve d Wright Vall ey P ro sp ect M e sa Forma tio n (= Pect en G ra vel )
Ij ord al assembl age (WEBB 1974 ) , but co mp rises o nly 4 pe rcent of the Larsemann Hill assembl ag e (Q UILTY
et al. 1991 ). At Coc kbu rn Isl and it cons tit utes be twee n 6 and 4 1 percen t in s ix of th e asse m blages (Ta ble
2) . Thi s de gr ee of va ria bility, its poor prese rvat io n and o fte n large size, s ugges ts it is p rone to surviva l
th ro ugh multiple ph ase s of recy cl ing w ithin th e Pli ocen e. Its spherical-s ubs phe rica l fo rm p robabl y fac ilitat es bo tto m transport w here pron ou nced wave ac tio n a nd c urre nts are d ominant.
M embers of th e Cass id u linidae a re a dominant co m po ne nt at La rsem ann H ill s (8 1 percent ) but le ss
significant in th e W rig ht Valley asse mb lage . In PNW 13 a t Cockburn Isl and , th is fami Iy contrib utes 12.5
percent to th e asse m blage. w hile in samples int erpr et ed as rec ycl ed (e .g . AG 2) the fig ure is e levate d to
90 pe rcent , in which case, preservatio n is o fte n very poo r.
lOO
%
poorest preservatio n
and largest tests
80
u..J
U
Z
«
Z
PNW 12
transport
and
biot urbation
<:0
60
AG3 0
~
O AG 2
00
o
0
Cl
o
o
00
40
best preser vation and wides t
range of species
20
.6..
o
o
Prospect Mesa Grave ls - Wright Valle y
Pliocene - Larsem ann Hills
Pecten Conglomerate - Coc kburn Island
5
10
15
20
NU M BE R OF SPEC IES
Fig. 8
Percentage dominance for the most common species in each of six Pect en Conglomerate assemblages plotted against total
species diversity. Similar assemblage data derived from Pliocene assemblages in Wright Valley (WEBB 1974 ) and Larsemann
Hills (Q U ILTY et a l. 11.)1.) I ) arc also plotted. Assemblage PNW 13 is considered to be closest to an original biocoenosis. All
other Cockb ur n Island assemblages. including SPE 12 used in H OI.I.i\ Nf)· S ( )I.) I 0 ) study, reflect varying degrees of restructuring in high encrgy littoral environmcnts. Arrows indicate progressive alteration of assemblages.
16 8
ANDRZEJ GAZDZICK I and PETER -NOEL WEHB
Cibic id idae mak e up I to 5 percent of the La rse ma nn Hill s and Wrig ht Valley asse mb lages, but may
be co ns iderab ly more a bunda nt at Coc kbu rn Isl an d . In sa m ple PNW 13 thi s fa mi ly co ntri butes 37 pe rce nt
to the assemb lage, a figure th ou ght to be a reason abl y acc ura te ta lly for the origi nal biocoen osis . Here,
prese rvati on is exce lle nt a nd the re is a wid e ra nge in test sizes. T hese large but so me ti mes fragi le tests
break down on tran sp ort a nd in the re-tran sp ort ed samp les suc h as AG 1, 2 a nd 3, a nd PNW 12 , the fa m ily
co ntributio n d rop s 12 pe rcent or less.
It is not e wo rth y th at Ehre nb ergina g labra HEIW N-A LLI:N et EARLAND. a for m ve ry co m mo n in prese nt- day polar fa unas. is presen t in mod era te a nd con sist ent number s at Larsem ann Hill s but is not present
in e ither W rig ht Valley or Cockburn Isl and asse m blag es .
M olluscs are co mmo n at a ll thr ee s ites , a nd at Cockburn Isl an d a nd W rig ht Valley sca llo ps are the
domin a nt ma c ro fo ssil. Ec hino ids are rep orted in both the Lar sem ann Hills a nd Cock burn Isl and asse m blages. La rge a nd ro bus t ec hi no id spines a re ex tre me ly co m mo n at Cock burn Isl and . T he presen ce o f thi s
group po ints to sedi me nt bioturbati on as a pot e nti al age nt in test recycl ing. S po nges are present at all
thr ee s ites and prob abl y co ntributed to the benthi c m ic roe nvi ronment s in whic h the for aminifer a lived .
M a ny of the large foramin ifera in th e Pect en Cong lo merate asse mb lages have been den sel y drilled by
pred ator s a nd thi s is a n add itio na l age nt in test di sintegrati on. Drillholes are pa rticul arl y a ppa re nt in
Cassidulina crassa, Cibicides refu lgens, a nd A nunoe lphidiella antarctica. W EBB ( 1972, 197 4 ) a lso noted
a high inc ide nce of pred at ion in Anunoelphi di ella an ta rctica fro m the Pecten G rave ls asse m blage o f
Wr ight Valley .
M OD ERN -D A Y POLAR FO RA M I N IFE RA L B IOTO PE ANA LOGS
We wi ll attempt to identi fy a mod ern po lar latitude a na log of the Pecten Cong lo merate fora mi nifera l
biofac ies. Here, we mu st exe rc ise ca utio n in dr awing too c lose a par all el since there ma y have been
significant ma rine pal eoclim ate co ntras ts bet ween the late Pli ocen e a nd present-day coasta l e nvi ro n me nts .
Most prese nt- day coastal a rea s are co ve red by seaso na l a nd in so me instances mult i-yea r sea- ice a nd th e
presence o f coasta l ice has not been dem on strat ed in the case of th e Pect en Co ng lo merate . Ne vertheless,
we beli e ve th at a reason a bl y close mod ern a na log to the Pect en Co ng lome rate (orarninifcr al asse mb lages
is prov ide d at Exp lore rs Cove, western McMu rdo So und (B ER NII ARD 19 87).
Th e Ex plore rs Cove study s ite e nta iled co ns ideratio n of a varie ty o f subtle seaso na l to dail y ph ysical
and ch emi cal perturbati on s, including sea -ice build- up a nd break out. a nd wave, current a nd tid al ac tio n.
O the r important fact ors taken into co ns ideratio n in BERNII ARD's ( 1987) st udy included sed ime nt a nd
biot op e tran sp ort into s lightly deeper wa te r a nd the introduction of orga nic rich terrestrial melt water fro m
nearby land. Wat er depth s chose n for the st udy ra nge d between 2.5 a nd 27 meters. and sa m pling si tes
ex te nde d no more tha n 55 meters offsho re. BER NIIA RD ( 1987) d istingui sh ed sev e n fo ra m inifc ra l biot op es ;
sha llow. bo ulde r, ope n deep -wate r (max imum water depth 2 7 m ). s po nge mat . se d ime nts underl yin g
spo nge mats, seaso na lly a nox ic (micro) basin , and anc hor ice . Th e number o f species per bi ot op e was
found to be o n the orde r of 5 to 7. Ge nera th at were widesp read a nd com mo n to mo st bi ot op es included ;
Patellina, Pyrg o, Globocassidulina, Cassidu linoides. Fu rsenk oina, Epistomi ne lla, Cibicide s, a nd Astro nonion . Th ese gene ra , or very cl ose relati vcs, a re a lso mem bers of the Pecten Cong lo me rate asse m blage.
T he megafaun a at Ex plorers Cove co ns ists of the sca llo p Adamussiuin co lbecki. rosse lid spo nges, ophiur o ids, astero ids, a nd gastro po ds. BERNII ARD ( 1987) rep orted high est live-d ead a bunda nce adjace nt to
boulder s and ben eath spo nge mats. The boulder biotop e possessed the hi gh est fo ram inifera sta nd ing stoc k
and tot al a bunda nce figures. Man y asp ect s o f BI:RNII ARD'S res ults mat ch th e ad mi tte d ly mu ch more
impe rfect dat a pro vid ed for the Coc kburn Isl and asse mb lages. O ne major differen ce is that 19 of the 60
spec ies investig ated by BERNII ARD ( 1987) we re agg lut inate d forms. Agg lutina ted tests may have been
presen t in th e Cockburn Isla nd Pecten Co ng lo me rate biofaces but di sintegr ated po st-mortem . Wave ac tio n,
tid al ac tivity, and/or bott om c urr e nts , appear to have played a mu ch g rea ter rol e in th e de velopment of
the Pect en Co ng lo me rate th an wi th th e Ex plo rers Cove e nv iro nme nt. It is possible th at phys ical perturbati on and destruction o f th e biot a, es pecially in near-littor al mic roe nvi ro nmc nts, was suppressed by
seasona l ice at Ex plore rs Cove, whe reas there may ha ve been littl e or no prot ecti on afforde d by sea-ice
ice cover a t Coc kb urn Isl and . Th e Ex plorer Cove an al ogy sa tisfies one as pec t in int erp retin g th e Pecten
Cong lo me ra te biot op e . At the latt er s ite we a re dealin g w ith a coasta l se tt ing, ve ry sha llo w wate r, and
high en ergy wat er co nd itio ns .
FORA M IN lfERA FROM T HE PECTEN CO NG L OME RATE
169
PALEOECOLOGICAL INTERPRETATIONS OF MACROFOSSILS
AND MICROFOSSILS FROM THE PECTEN CONGLOMERATE
TOTA L FOSS IL ASS EMBLAGE
Th e fo llowi ng fossi l g ro ups ha ve been docum ent ed in th e Pecten Cong lo merate : calcareo us nann opla nkto n-rec yc led (G AZDZICKA a nd G A/DZICK I 199 4 ), fresh water and marin e diatom s ( HARWOOD 1986),
rad iol arian s (HARWOO D 1986 ; th is investigatio n ), s ilicofl agell at es ( HARWOOD 1986 ), fora minifera-in situ
(HOLLAND 191 0 ; HENNI G 191 0 ; thi s in vesti gati on ), fo ramin ifera-rec ycl ed (G A/DZICK A and G AZDZICK I
1994 ; thi s in vesti gati on ), spo nges ( HARWOOD 19 86 ), cc hino ids (this in vesti gati on ), os tracods ( HENNIG
191 0 ; SZCZECIIURA a nd BLASZYK 1996 thi s vo lume ), bryozoans ( HENNIG 1910), barnacl es (H ENNIG 1910),
mollu scs ( HENNIG 1910: W ILCKENS 192 4 ; SOOT-RYEN 195 2 ), a nd brachi opod s (HENNIG 1910; Buc KM AN
1910 ). No terrestri al macr o foss il materi al , s uc h as wood o r leaves has been reco ver ed .
Th e most di verse foss il g ro ups are diat om s (2 1 ge ne ra a nd 57 spec ies), for aminifer a ( 19 ge ne ra and
24 spec ies), br yo zoan s ( 10 ge nc ra and 12 spec ies), brachi op od s (3 ge ne ra a nd s pecies), and mollu sc s (3
ge ne ra a nd spe cies ). Th e ma c ro- a nd mic rofauna is o bv io us ly marine but HARWOOD ( 1986) not ed the
presen ce o f rare fre shw ate r di atom s am on g ma rin e the d iat om ta xa. Debri s o f a ll mac rofossil g ro ups is
enco unte red in mic rofossil prepar ati on s (Ta ble 2). No int act ec hino ids have been re po rted but we find rare
ec hi no id plat es and ve ry co mmo n cc h ino id sp ine s in mic rofo ssil pre parati on s (Ta ble 2) . A ltho ug h the
pion ee r paleontolo gical wo rk by the 1901 -1 903 Sw ed is h So uth Pol ar Ex pe di tio n, in all fos sil groups, is
in need o f syste ma tic re visi on , the tot al Pect en Cong lomerate b ioto pe co nta ins mo re than 50 ge nera a nd
100 spec ies . Future field co llec tio n and lab orator y dat a reduction is likel y to inc rease th e dive rs ity a nd
abunda nc e wit hi n the Pecten Cong lo merate bio to pe .
BAT HYM ET RY AN D TE R R EST R IA L IN F L UE NC ES
T he bat hymetry of the dep osit can be es t ima ted from seve ra l o f the g ro ups prese nt. HARWOOD ( 1986)
rep o rts that 7 ge nera a nd 14 spec ies of di at om s are assoc ia ted w ith wate r depths less th an 50 met e rs.
A mo ng the fo ra mi nifera, the ve ry large mili olinell id Pyrg n (P I. 34 : 1- 3) a nd lar ge e lphid id Ammoelphi diella (PI. 37: 5-7 ; PI. 38 : 1- 10; Text -fig . 7a-d ) a re for ms w hic h are a lso expec ted to have favo red
enviro nme nts in the phot ic zo ne . In ge ne ra l. th e tests o f for am inife ra are both lar ge a nd heavil y calc ifie d
and aga in thi s po int s to a shallo w coasta l e nv iro nme nt. Both the fora m in ife ra a nd the mac ro foss il g ro ups
ha ve bee n subj ec ted to a high degree of a bras io n a nd fragm entati on (Tex t- fig. 7b- d ). We ta ke th is to
indi cate high e ne rgy co nd itio ns close to a s hore line within th e reach of wa ve base , curre nt ag ita t io n and
frequent so rting. Both HOL LAND ( 19 10) and HENNIG ( 19 10) beli e ved that the for aminifer a might be
assoc iated w ith bracki sh es tua rine co nd itio ns , and HENNIG ( 19 10, p. 59 ) suggested the possibl e affec t of
icebe rgs as a so urce of red uce d sa linity. We ha ve no info rmati on o n degree o f run o ff o f ter rest rial wa te r
at the coastline and no record of ice -be rg presen ce . Ho we ver, both suggest io ns s ho u ld be kept under
co nside ra tio n. O ne intr ig ui ng ob se rv at ion is th at the test s o f fora m ini fe ra, parti cul arl y in the as se m b lage s
that a rc co ns ide red to havc ex pc ricn ccd rep eat ed tran sp ort , are iron-st ai ned to a deep red-brow n co lor. It
is prob abl e that the mobile iron wa s deri ved fro m th e deepl y weathe red volcanic terra in of flows a nd
tu ffaceou s sed ime nts fro m whic h par t of the Pecten Co ng lo merate wa s deri ved . If iro n-r ich wa ter s we re
perco lati ng th rou gh the Pecten Co ng lom erate at a litt o ral site, then cons ide rab le pen econtempo ran eou s
and/o r po st dep o sition al dr ain age fro m terrest rial s ites is impli ed.
M ARI N E PAL EO CLI M AT E AT LITT OR AL-I N NER S HELF S IT ES
D URI N G TH E LATE PLI O C E N E
HENNI Ci ( 19 10) int er pre ted the biogeogra ph ic a nd th e rm al as pects o f th e Pecten Co ng lo me rate mac rofossil asse m blage th rou gh com pariso n w ith e nv iro nme nta l tol er an ces of the sa me exta nt taxa in the
So uthe rn Ocean , Patagoni a, Fa lk la nd Isl ands a nd C ha tha m Isl ands (o ff Ne w Ze a land ). He not ed th at half
the spec ies in the Coc kburn Isl and asse mb lage live in wate r temper atures bet ween 2 and more th an 10°e.
Fo r thi s reason th e Pecten Cong lo me rate fauna has been c ited in mo st liter ature as indi catin g pr e- o r
inte rg lac ia l conditi on s. H ENNI (;'S ( 1910) assess me nt o f pal eot emperature based o n macrofuun as , sho uld
be re viewed to asce rta in its va lid ity.
170
ANDRZEJ GAZDZICK I a nd PETER-NOEL
WEBB
IMPLICATIONS FOR TERRESTRIAL PALEOGEOGRAPHY
AND PALEOTOPOGRAPHY
S ince the Pecten Cong lo merate deve loped at a coastline, its lith ological and pre-Pl iocen e paleon tological
co nte nt might reveal so methi ng abo ut late Pliocene terrestria l paleogeograph y and pa leotopography. La rge
clasts of Jam es Ross Islan d Volca nic Group rocks in the for ma tio n (Text-fig. 6) indi cate a local terrest rial
so urce . T he presence of recyc led fora m inifera an d calcareo us nann o plankton fro m the Mara mb io Group
(U pper Cretaceous) suggest either deep dissection of the vo lca nic cove r so as to re lease Cretaceous roc ks to
eros io n, or the ex iste nce o f a highl and of Cretaceous rocks , or both. S urpris ing ly, we have recovered no
recyc led mic rofo ssils fro m the Pa leocene Sobral or Eocene La Meseta Forma tions, ind ica ting that they were
not w ithi n the ca tc hment area o f the Pliocen e Pecten Co ng lo me rate or not ex posed above sea level in the
Pliocen e. It will be recall ed from Te xt-fig . 4 that the La Me seta Formation rocks a lmost directl y und erl ie the
Pecten Cong lomerate . No evi dence for an O ligocene -M iocene succ ess io n, re prese nted by Cockb urn U nco nformity U 3 (i n Tex t-fig . 4) , has been recovered a nd we dedu ce tha t no rocks of this age spa n we re above se a
level in the latest Pl ioce ne .
IMPLICA TIONS FOR TECTONIC HI STORY
La te Ce nozo ic tectonic events in the Jam es Ro ss Isl and a rea (inc luding Cock burn Isl an d ) are cons idered
by severa l aut ho rs . B IBBY ( 1966) wrote of fa ultin g and subs ide nce (s ub ma ri ne) assoc iated with the eruptio n
of M ioc ene J am es Ro ss Isl and Volca nic Gro up rocks . Furthermo re , he wrote (p. 36), " W he n thi s vo lcanic
e pisode e nde d a res um ptio n of sha llo w- wate r sedi me ntation res ulted in the for mat io n of the Pli ocen e
Pect en Cong lo me rate" . BIBBY ( 1965, 1966) proposed post-Pli ocen e upl ift of the e ntire area a nd c ited the
existe nce o f yo u ng C?Pleis toce ne) rai sed beach es as the most obv ious evi de nce .
NELSON ( 1975, pp. 6, and 59) e m phas ized emerge nce o f top ograph y si nce the e nd of the Mi occn e, and
used the present e leva tio n (220-250 m) and ass ume d age (Plioce ne) o f the Pecten Co ng lo me rate o n Cockb urn
Island as a datum , to suggest (p. 60), " it is feasible tha t at least 4000 It . ( 1219 m) of re-emergen ce of the
area (i .e. Jam es Ross Island area) had ta ke n place before the c lose of the Pliocene" , As no ted ea rlie r, we
mu st take into co nside ratio n w hat was ac tua lly meant by M iocene a nd Pliocen e, ev e n twenty years ago. In
so me olde r tim e sca les the Mi ocen e-Pli ocen e boundary was place d at 12 Ma rath e r than the present 5.2 Ma .
A DIE ( 1964) included th e Coc kburn Island Pecten Cong lo merate locali ty in his Scot ia Ar c a nd Graha m
La nd survey of past sea- leve ls. He attr ibuted the presen t ele vatio n of th e deposit (220 -250 m) to a Pliocene
high sta nd o f int ergl acial sea le vel. T his was also a view e m phas ized by FAIRBR IDGE ( 1952). No es tima tio n
of th e ro le of tec toni c upli ft was incorporated in these views .
G ive n o ur conc lusio ns o n pal eob a thyme try, that th e Pecten Co ng lo merate re prese nts a sho re line
biofac ies deposi ted a nd de vel op ed in wate r depth s of no more th an 50 mete rs , and that deposi t is
approxima te ly 250 met er s a bove present sea level, there is the n, the poten tial for approx imate ly 300 me te rs
o f upl ift since t ime of de pos itio n. Acce pting a n age span for the depos it to be 2.8-2 .0 Ma (HARWOOD
1986 ), the rat e of upli ft fo r the Coc kburn Isl an d region lies somew he re in the ra ng e of 100- 150 rn/rn. y,
T he present elevatio n of th e Pecten Co ng lo merate o n Cockb urn Isl an d is a mong th e high est for a ny
ex posed marine Pliocene se d ime nts in A nta rct ica (W EBB 1972. 1974 ; EGGERS 1979; Q UIU'Y et al. 1991 ).
U plift m ay be du e to reg io na l e merge nce , local fault ing or so mc co m binatio n of th e two. O ur ea rlie r
d isc ussio n o f pos sibl e faulting on Coc kb urn Island te nds to rul e ou t this facto r as a do mi na nt in flue nce .
Th e Pecten Co ng lo me rate pro vid es a useful lat e Pli occn e tect oni c d atu m in thi s reg io n of the A nta rct ic
Penin sul a. S ho uld pal eobathym et ric dat a become ava ilab le from we ll ca librated mar ine intercal ati on s
wi thi n the lower part of th e Jarn es Ross Isl and Volca nic G roup, docum en tation of the upl ift h ist o ry could,
be ex te nde d ea rlie r, to th e latest M iocc ne (c . 6-7 Ma) .
CONCLUDING REMARKS
Th e Pecten Cong lomerate was dep osi ted during th e late Pli occn e, possibl y during o ne of two high stands of sea le vel reported by HAQ et al. ( 1987) be twee n 2.4 a nd 3.5 M a. T he stra to ty pe o n Cockburn
Island is a n e ros io na l remnant and may represen t a rel ati vel y short spa n of late Pli ocen e ti me . It's e levatio n
FOR AMINIF ERA FROM TH E PECTEN CONG LOMERATE
171
of 220- 250 meters above se a lev el is att ribute d to a po st-depositional uplift rate of between 100 and 150
meter s/million yea rs .
A diverse ma cro- a nd microfaunalflora of more than 100 spec ies ex iste d c los e to a coa stline , in wat e r
no deeper than 50 met er s. Th e form ati on co nta ins th e most pal eontologicall y diverse Pliocen e suc cess io n
known in Antarctica. The Pecten Co ng lo me rate and its fo ssil assemblage s are situated at latitude 64 °S,
the northernm ost of th e known A nta rc tic Pliocen e localiti es. Thi s se tt ing provide s a potentiall y important
biogeogr aphic link between th e sha llo w marine asse mb lag es o f South America and o the r parts of Antarc tica, and a n understanding o f coastal condition s in th e extre me so uthwes t Atlantic Ocean durin g th e
Pliocen e . Early investi gators were correct in int erpreting th e se fos sil ass e m blages as representative o f
int er glacial condition s.
Th e fo ram ini fer a l fauna sha res many feature s in common with Pliocen e assemblage s in th e so uthwes tern Ro ss Se a- Tran santarctic Mountain s, a nd Lar sernann Hill s, near Prydz Bay, East Antarcti ca. Similarity
am on g such wid ely se pa rate d coast al foraminiferal biotop e s make s it lik ely th at communicati on occurred
around th e coas ta l periphery of th e continent o r via int erior seaways . Foraminiferal and other pal eontological ev ide nc e suggests th er e is littl e lik elihood that thi s re gion of West Antarctica w as subme rge d
ben eath e ithe r ice s heets, ic e stre ams o r ice she lves, although th e pre sence of season al se a-ice cannot be
ruled o ut.
Th e pal eo climat e at th e coastli ne in th e Co c kburn Isl and re gion a nd in othe r coastal re gions of Pli ocene
A nta rctica appears to ha ve been pol ar but mild and th e term deglaci al seems appropriate. Our data sup po rt
arg ume nts which call for quite widespread deglaci al co astal marin e and coastal terrestri al e nv iro nm ents
during significa nt inte rvals o f Pliocen e tim e (S PEDEN et al . 196 2 ; W EH B 1972, 1974, 1988, 1990, 1991 ;
W EB B et al. 1984; HARWOOD 1986, 1991 ; WE BB and A NDREASEN 1986 ; ISHMA N and W EBB 1988; PICKARD
et al. 1988 ; Q uu .rv et al . 1991 ; W EBB and HARWOOD 1991 ; BARRWETT et al. 199 2; a nd ISIIM AN and RIECK
1992). Late Pliocene terrestrial climat e in th e Tran santarcti c Mountain s at 85 °S latitude w as polar and
involve d g lac ia l co nd it ions (Mc KELVEY et al . 1991 ), but annu al climat e a llowed for the ex iste nce and
pr opagation of low diver sit y shru b for est s (W EH H and HARWOOD 1987 , 199 3). Ac cording to the Pliocene
"T ra nsa ntarctic Landbridge" hyp othesi s of W EBB and HARWOOD ( 1993) possibil itie s e xisted for both
marine and terrestri al linkages through West Antarctic a between th e Antarctic Penin sula, th e Tr ansantar ctic
M ountain s, and perh ap s othe r part s of Eas t Antarctica.
The Pliocene degla cial condition s whi ch we hav e interpreted for co astal marine and coas tal terrestrial
env iro nme nts might be ex pected to be refl ect ed in the offsh ore deep marin e rec ord. Unfortunately , no marine
Pliocen e rec ords ex ist for th e so uthe rn Weddell Sea region. Tw o di stant data points are availa ble for
con sid er ation. Thes e are, th e Maud Rise-Agulhas Transect (A BELMA NN et al. 1990 ) a nd the Ocean Drilling
Pro gram Sit e 697-J ane Ba sin (Bu RcKLE et al. 1990). Th ese sites a re 2500 and 900 kilomet ers distant
respecti vel y from Co ckburn Island. Usin g abundance patt erns and species co mpos itions, ABELMANN et al.
(1 990) reco gni zed a peri od between 4 .8 and 3.5 Ma wh en sur face water s were between 5 and l O'C warmer
than present. During the Pliocen e c lima tic optimum (4 .8 to 4.4 Ma ) severa l low and middle latitude siliceo us
spec ies invad ed the Southern Ocean . Maj or changes had occ urred in de ep sea silice o us g ro ups by 2.6 to 2.4
Ma and there wa s ev ide nce for sea-ice in the Weddell Sea . To accommodate th ese o bservations, on e
hyp oth es is we mi ght pursue , is that a Pecten Co ng lo me rate-like ma cro- and microfauna-microfl or a, whi ch
als o had suba ntarctic-co ld temper ate affinities, entered Antarctica during the early Pliocen e (Plioc en e Climatic Optimum) and surv ived as th e late Pliocene Pecten Con glom erate asse mblage . In the second study
cit ed ab o ve , BURc KLE et al. (1 990) used di atom data to deduce that durin g the Gauss and early Matuyama
C hro ns (3 .5 to 2 .0 Ma), th e inter val o f tim e during whi ch the Pecten Conglomerate wa s deposit ed along the
sho relines o f West Antarctic a, there was sea-ice cove r on the waters o ve r the Jane Basin and ice growth o n
Antar ctica. While thi s ma y ha ve been possibl e so me w he re in Antarc tica , the Cockburn Island data indi cate
that ther e was no ice shee t de veloped at the coastline .
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Palaeontologia Polonica, No. 55, 1996
A. GAZDZICKI and P.-N. WEBB: FORAMINIFER A FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND , ANTARCTIC PENINSULA
PLATE 34
Pyrgo fo m asinii
CH A PM AN
et
P A RR,
1935
159
Fig. I. Sample AG I, ZPAL FX XXVIII/l. x 50.
Fig. 2. Sample AG 2, ZPAL FXXXVIIII2, x 45.
Fig. 3. Sample AG 1, ZPAL FX XXVIII/3, x 40 .
160
Pseudonodosaria sp. .
Fig. 4. Sample PNW 13, x 100.
Fig. 5. Sample AG I, ZPAL FX XXVIII/4, x 40.
Lenti culina gibba
(D ' O RBIGNY,
160
1839)
Fig. 6. Sample PNW 13, x 210.
Fissurina cf. semimargi nata (RE USS, 1871)
160
Fig. 7. Sample PNW 13, x 225.
Ang uloge rina angulosa
( W ILLI AM SON,
Fig. 8. Sample SPE 12, x 77.
Fig. 9. Sample AG 2, ZPAL FXXXVIII/5, x 87.
Fig. 10. Sample AG 2, ZPAL E XXXVIII/6, x 135.
1858)
162
Palaeontologia Polonica , No. 55, 1996
PI. 34
A. GAZDZICKI and P.-N. WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND. ANTARCTIC PENINSULA
Palaeontologia Poloni ca, No. 55, 1996
A. GAZDZICKI and P.-N. WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND, ANTARCTIC PENINSULA
PLATE 35
Cassidulina crassa
D' O RBIGNY,
161
1839
Fig. I. Sample SPE 12, x 80.
Fig. 2. Sample SPE 12, x lOO.
Fig. 3. Sample SPE 12, x lOO.
Cassidulinoides park erianus
( B RADY,
1884)
161
Fig. 4. Sample PNW 12, x 75.
Fig. 5. Sample SPE 12, x 120.
Fig. 6. Sample AG 3, ZPAL E XXXVIIIn , x ISO.
Globo cassidulina subglobosa
(BRADY ,
1881)
161
Fig. 7. Sample AG 2, ZPAL F.xXXVIII/8, x 105.
Fursenkoina ef. earlandi
( PARR,
1950)
162
Fig. 8. Sample PNW 13, x 135.
Fig. 9. Sample PNW 13, x ISO.
Epistominella vitrea
Fig. ID. Sample PNW 13, x 250.
Fig. I !. Sample PNW 13, x 2 15.
PARK ER,
1953
162
Palaeontologia Polonica , No. 55, 1996
Pi. 35
A. GAZDZICKI and P.-N. WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND. ANTARCTIC PENINSULA
Palaeontologia Polonica, No. 55, 1996
A. GAZDZICKI and P.-N. WE BB: FORAMINIFERA FROM T HE PECTEN CONG LOME RATE (PLIOCENE)
OF COC KBURN ISLAND, ANTARCT IC PENINSULA
PLATE 36
Cibicide s lobatulus
(WAL KER
et J ACOB, 1798)
163
Fig. I. Sample PNW 13, x 485.
Fig. 2. Sa mple PNW 13, x 11 0.
Fig. 3. Sample PNW 13, x 435 .
Cibicides refulgens
DE M ONTFORT,
1808
162
Fig . 4. Sample PNW 13, x 80.
Fig . Sa-b. Sample PNW 13, x 125.
Fig. 6. Sam ple PNW 13, x 105.
Non ionella bradii
Fig. 7. Sample PNW 13, x 240.
Fig. 8. Sample PNW 13, x 260.
( C HAPM AN,
1916)
163
Palaeontologia Poloni ca, No. 55, 1996
PI. 36
A. GAZDZICKI and P.-N. WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND, ANTARCTIC PENINSULA
Pala eont ologia Polonica, No. 55, 1996
A. GAZDZICKI and P.-N. WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND , ANTARCT IC PENINSUL A
PLATE 37
Melonis sp.
163
Fig. l a-b . Sample PNW 13, x 525.
Fig. 2. Sample PNW 13, x 255.
Cribronon ion sp.
163
Fig. 3. Sample PNW 13, x 205.
Fig. 4. Sample PNW 13, x 235.
Ammoe lphidie lla antarctica
C ON ATO
et
SEGRE,
1974
164
Fig. 5. Spiral side view, paired septal foramina infilled by matrix or ornament, sample PNW 12, x 70.
Fig. 6. Broken test, spiral side with chambers at left, umbilical side right, note triangular shaped septal cana l
between septa towards umbilical side of test, sample PNW 13, x 105.
Fig. 7. Spiral side view, last chamber strongly deflect ed to umbilical side of test, sample PNW 12, x 55.
Palaeontologia Poloni ca, No. 55, 1996
Pi. 37
A. GAZDZICKI and P.-N. WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND, ANTARCTIC PENINSULA
Palaeontologia Polonica, No. 55, 1996
A. GAZ DZICKI and P.-N. WEBB: FORAMINIFERA FROM THE PECTEN CONG LOME RATE (PLIOCENE)
OF COCKBURN ISLAND , ANTARCTIC PENINSULA
PLATE 38
Ammoelphidiella antarctica
C ON ATo
et
S EGRE,
1974 . . . . . . . . . . .
164
Fig. I. Spi ral side view, highly convex , rows of paired septal fora mina just visib le, thick test wall, finely pu stulose,
sample AG 3, ZPAL FXXXVIII/9, x 80.
Fig. 2. Spiral side view, test wall finely pustulose, spiral side is convex, sample AG 3, ZPAL FXXXVIIUI0, x 100 .
Fig. 3. Spiral side view of a large probably microspheri c test, last chamber missing, this test exhibits a tendency
toward streptospiral coi ling, abo ut ten chambers in the final whorl, spiral side sutures are so mewhat curved,
paired septal foramina extend from spiral to umbili cal sides, a few foramina in the spiral sutures , test has
been battered and predated (bored in one place), pustulose orna ment may have been worn off, sample AG I ,
ZPAL EXXXV IIUI I, x 45.
Fig. 4. Umbilical side view, umbilical area is cove red by plate covered with pustulo se orna ment, sutures are radial ,
se ptal canal beneath cove r between two rows of foram ina and raised ornament, sample AG I , ZPAL
EXXXVIIUI2 , x 90.
Fig . 5. Umbilical side view, last chamber has poorly developed ornament, sample AG I , ZPAL E XXXVIIII13 ,
x 105.
Fig. 6. Broken test from umbili cal side , sample AG 3, ZPAL E XX XVIIII14 , x 80.
Fig. 7. Broken test viewed from umbili cal side, attachment of final whorl of chambers to previous (?initial) whorl,
slightly curved sutures (base) that pass to umbil ical region exhibit traces of aerial septal foram ina, pustulose
orna ment of previous chambers appears to have been resorbed, sam ple AG I, ZPAL E XXX VIIUI 5, x 50 .
Fig . 8. Spiral side of test, rows of paired septal foramin a separated by roof of septal canal wall, sample AG I ,
ZPAL E XXXVIIUI 6, x lOO.
Fig . 9. Pustulose orna ment, sample AG 3, ZPAL E XXXVIIU17, x 500.
Fig . 10. Pustulose ornament, sample AG I, ZPAL EXXX VIIUI8 , x 1200.
Palaeontologia Polonica. No. 55, 1996
PI. 38
A. GAZDZICKI and P.-N . WEBB : FORAMINIFERA FROM THE PECTEN CONGLOMERATE (PLIOCENE)
OF COCKBURN ISLAND. ANTARCTIC PENINSULA