Devo INTR ODUCTIO ON P eozoic atf erlie a vast are million

CA NADA
G. TELFOR
A BSTR RACT
The M ose Riv er Basin is an in tracrat onic Paleoz oic sedim enta ry basi n un derlyin g th e Ja mes Bay L owland of n or theas tern Onta rio and containing
strata rangin g from Ord dovicia n to Uppe r Devon ian age. Exce pt alo ng g th e mildly defo rmed d easte ern m argin st rata a re gene ra lly flat-lyi ing. Devonian
carbon ates, sha les, evapori tes and mino
ssic a nd Cretac eous clastic sediments o ve rlies the D evonian rocks inthe sout heastern pa rt of t he basin and the en tire region is blankete d by Pleist ocene
glacial d eposits and Rec ent mari ne clays.
Th e Devon ian suc cession com pris es, in asce nding order: Lower Devo nian Kenogam i R ver (upper part only; dolom mitic lim estone), St ooping River
(mainly lim estone ) and Sextan
s), M urray Islan d (lime tone) and W lli ams Island (s hal , carbo nates) Formation ; and the Up per Devoni n Long Ra pids Form ation (b lack shale,
mudstone minor carbo nate s).
The apparently s mple s tratigrap hy s com mpli cated by lateral fa cies variations, including a co ntinental to marine tr ansition am ong t he Low wer
Devo
INTR ODUCTIO ON
P eozoic
atf
erlie a vast
are
million 2
son Bay. T
ibute d amon
ain te ctonic e lem
viz.
se Riv er and oxe Ba ins, and th e Foxe
Chan nel-H udson S trait
ben syst
How ever, D Devonian str
ins.
like the ot
f the
atfor m,
y the w
which are nnel an d
Strait , the Moose
in is
under lyi
mes Bay
tario (Fig. 1). A
all segm
extend s i nto the adjo
eath he wate rs of J mes B
The
underlies an
The M o2os e Rive r B ded approx
of
05' a nd
nd
gitudes
ti
. M os t of t
hore por ion of th basin is c haracy a ve ry fla
y, s parsely vegeta
plain.
ess is po oor, bei
a single
ine along
the e
tern margin of the low land
rm
gra
are distributed am
em.
men
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sm
ay.
e on
are
ooson
on Jam es B Bay.
ossed by s
al major north to no
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, includ
evera ma or nort tagami rtheast flo
ng t rm the Moos attagam i and
farthe aib i (which m
and Attaw api
. O and
farther n orth eozoic
stricted t
f Paleozo or tribu
ms.
Th
e River Basin (Fig. 1) is
Th fault c ontrolled an
def ined ph ysiogra
north facing esca
ment an d an abrupt chan ge from lly by a
nort mpy cing escarpme
vers merge
ps o
nd weste
s of the b asin (a
ive y sharp d lowland
edim
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are
cambrian
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rain
passes i nto the ma
ange. H However, i
he M
ive r
is cle rly separa ted f om the H Hu dson Bay Basin by a basement struc tur al hi gh refer red to the Cape Henrietta Maria
A ch (Fig. 3). Th surf
of this no thea st trending f eature
is mark ed by
of Ar chaean and Prote
oic r ocks
kno w n as the S utton L ak es Inlier. H owever, the a rch w
not a omplete ba rrier to Paleoz oic sedim entation and , in
places contains a thin seq
e of Upper Ordo vician and
Lower Sil urian limesto nes and
ly on n Prec ambrian t
in.
sequence of Devonian stra
the Moose R ver Basi
ratigraphic r
ips w ith
the Moose Ri though d
ins. Parts of
e Devo nian se
sive inves tigation
lated by po
ential hy drocarbon and i with in
min eral ated by pot entia sell and
Telfor d, 1984; Ru ssell etal, 1985;
on and ssell and
Te 85). There efore, th e present pap
s based on and Telfo
an area
ace
roz
uenc
erra
ne
ens
es source
as
revious rep orts, pa
he ma
tions of
the Ge log ical S urv ey o f Canada (e.g ., Sanfo d an d Norris,
1975), as
ell as o n prelimi nar y re sults an d ongoing
activitie
w
REG IONAL
tation
ose
OLO GIC AL SETTING
tent sedimenough m Bas h of Phane ite o f inte me. Nevertheles s,
GEO
Copyright © 2009 by the CMaenmaodiira 11n234 S (o1c98ie8ty) of Petroleum Geologists.
124
Telford
Paleozoic units is from Sanford and Norris (1975).
relatively stable tectonic element, as evident by the thin
Phanerozoic cover of less than 1000 m.
Paleozoic strata range from Middle Ordovician to
Upper Devonian age (Fig. 2) and consist of approximately
700 m of marine carbonates, shales, evaporites, and minor
marine and continental clastic rocks. The Ordovician to
Lower Silurian strata are confined to the western and
northern margins of the basin so that, in much of the
remainder of the region, the Upper Silurian or Devonian
rocks rest directly and unconformably on Precambrian
basement (Russell et al., 1985).
Composite thickness of the Ordovician and Silurian
strata is about 300 m. The former consist mainly of shallow
marine or supratidal carbonates, probably representing a
minor transgression from the northwest over the Cape
Henrietta Maria Arch/The succeeding Lower Silurian
sequence is dominated by marine carbonates consisting, in
part, of a basin margin reef complex and associated carbonate units positioned along the southern side of the arch. The
only Silurian strata that are reasonably widespread in the
basin are those of the lower and middle members of the
Kenogami River Formation.
Devonian strata thus make up most of the Paleozoic
stratigraphic sequence in the Moose River Basin. They have
a composite thickness of about 400 m and extend throughout the central and eastern parts of the basin (Fig. 1).
Through much of this area the Devonian rocks rest directly
upon Precambrian basement. They are well exposed near
the eastern margin of the basin, along the Abitibi and
Mattagami Rivers, and much of the data used in this report
and previous studies has been gathered from outcrops in
this region.
The Paleozoic rocks of the central Moose River Basin
generally comprise undisturbed, flat-lying strata, except
for beds affected by depositional dips around bioherms and
reef complexes. However, basin marginal areas have experienced significant tectonic activity and the Devonian
sequence in particular is occasionally disturbed by faults
and small scale folding.
Recent studies suggest that several episodes of
epeirogenic activity on the Hudson Platform affected the
deposition and subsequent history of the Paleozoic rocks of
the Moose River Basin. This produced several regional dis-
conformities and the basin margin structural complexities.
The epeirogenic events are thought to have been associated
with horizontal plate movements along the southeast and
northeast margins of the North American continent. Sanford (1987) has demonstrated the coincidence of Hudson
Devonian Moose e R . Basin , Canad
BFiagsuinr.e 2: Paleozoic and Mesozoic stratigraphic units in the Moose River
Platform epeirogeny with plate movements during the Early
to Middle Ordovician, Late Ordovician, Early Silurian, and
Early and Late Devonian. Further tectonism, including
emplacement of lamprophyric and kimberlitic intrusives in
the Devonian strata of the southeastern Moose River Basin
affected the region in the Middle to Late Jurassic.
Devonian strata in the southeastern part of the basin are
unconformably overlain by units of Middle Jurassic (Misuskwia Beds) and Lower Cretaceous (Mattagami Forma125
tion) age (Fig. 2). These are probably the product of greater
erosion of the adjoining Precambrian uplands due to tectonic events of that period. The Mesozoic deposits consist
of a variable thickness of flat-lying, unconsolidated nonmarine sands and mudrocks. The Mistuskwia Beds, characterized by coarse quartzose sands and varicolored clays,
appear to be of predominantly lacustrine origin. The disconformably overlying Mattagami Formation consists of
massive silica sands, kaolinitic mudrocks and minor gravel
and lignite and formed in a high constructive, possibly
anastomosed segment of a major river system draining an
extensive tract of the Precambrian Shield from south to
north (Telford and Long, 1986). Maximum known combined thickness of the Mesozoic units is 185 m.
All of the Paleozoic and Mesozoic units are blanketed
by a sequence of Pleistocene glacial and glaciolacustrine
deposits, and Recent marine clays, peat and muskeg. These
"overburden" sediments are of variable thickness, ranging
up to 200 m. Their complex depositional history has only
recently begun to be unravelled (see Shilts, 1986).
PREVIOUS DEVONIAN STUDIES
Much of the early geological work in the James Bay
Lowland was related to lignite deposits (now known to be
part of the Lower Cretaceous Mattagami Formation) on the
banks of the Abitibi River near Onakawana, about 90 km
south of Moosonee. Their occurrence was known as early as
1672 by the first English speaking settlers at Moose Factory
(across the Moose River from the site of present-day Moosonee).
The earliest known report on the geology of the Hudson
Bay territories was by Isbister (1855) but it was not until the
late 19th and early 20th centuries that detailed investigations
of the James Bay Lowland took place. Between 1871 and 1912
Robert Bell of the Geological Survey of Canada wrote 22
reports on the geology of the lands surrounding Hudson
Bay, including aspects of the Devonian geology of the
Moose River Basin. Sanford and Norris (1975) provide a
comprehensive review of this early work by Bell and others
so that only a selection of the pre-1975 works relevant to the
Devonian geology is discussed here.
For example, Savage and Van Tuyl (1919), Williams
(1920a, b) and Kindle (1924) established the basic stratigraphic framework for the Devonian rocks of the Moose
River Basin. Dyer (1928) summarized all known information of the Paleozoic geology of the basin and, through his
own expeditions to the region, contributed significantly to
knowledge of the Devonian geology.
In 1930 the Ontario Department of Mines drilled
Onakawana A, the first drillhole in the Moose River Basin
to penetrate through the Phanerozoic sedimentary sequence
to the Precambrian basement (Dyer and Crozier, 1933). The
Paleozoic section in this drillhole was made up entirely of
Middle and Upper Devonian strata and Onakawana A
became a standard reference section for the Devonian of the
eastern Moose River Basin. However, over time the impor126
tant drill core samples from this section were lost and
application of revised stratigraphic nomenclature became
difficult. Thus, fifty-five years after completion of
Onakawana A, the Ontario Geological Survey drilled
Onakawana B at the same location (Sanderson and Telford,
1985). Results of this recent drilling are presented in discussions of the individual stratigraphic units.
Other than a geological reconnaissance of the Moose
River Basin, aimed at establishing its petroleum potential
(Martison, 1953), and a number of paleontological studies
referenced by Sanford and Norris (1975), little attention was
given to the Devonian geology of the region until the
mid-1960's. In 1966 the Ontario Department of Mines carried out a major helicopter supported mapping program of
northeastern Ontario (Operation Kapuskasing), which
included part of the Moose River Basin and introduced
much hitherto unpublished subsurface data (Bennett et al.,
1967). Then, in 1967, the Geological Survey of Canada
mounted Operation Winisk, an air-supported geological
reconnaissance survey covering the entire Hudson Bay
Lowlands (Sanford et al., 1968). Information on the Devonian geology of the lowlands, and the first modern synthesis
of the Devonian stratigraphy of the Moose River Basin was
reported by Sanford and Norris (1975).
During the past decade the Ontario Geological Survey
has carried out a number of surface and subsurface investigations in the basin (including the drilling of Onakawana
B), mainly aimed at assessing the lignite, oil shale and
industrial mineral resource potential of the region (e.g.,
Telford and Verma, 1982; Russell et al., 1985). As a result of
these programs and follow-up activities a substantial volume of new data has been generated, especially relating to
the Devonian geology of the southeastern Moose River
Basin. This forms the basis for stratigraphic refinements of
the Devonian suggested in the present paper.
DEVONIAN STRATIGRAPHY
The Devonian succession in the Moose River Basin
consists of, in ascending order, the Kenogami River (upper
middle and upper members), Sextant, Stooping River,
Kwataboahegan, Moose River, Murray Island, Williams
Island and Long Rapids Formations (Fig. 2). All but the
Sextant and Long Rapids Formations are marine carbonate
units, with significant evaporites in the Moose River Formation and shale in the Williams Island Formation. The
Sextant Formation is a mainly terrigenous unit, ascribed by
Stoakes (1978) to reworking of coastal sediments, but
referred to
other authors (e.g., Sanford and Norris, 1975)
as a continental facies. The Long Rapids Formations consists mainly of black shales and green mudrocks with minor
carbonate horizons.
The following formation descriptions are drawn largely
from summaries of recent important articles (e.g., Sanford
and Norris, 1975; Norris, 1986), combined with new data
from the Ontario Geological Survey programs and other
activities in the region.
Telford
by
KENOGAMI RIVER FORMATION
This unit spans the Silurian-Devonian boundary (Fig.
2) and, as redefined by Sanford et al. (1968), consists of
three members as follows
Upper member: brown and tan dolostone, dolostone
breccia; 11-33 m.
Middle member: red and green gypsiferous mudstone,
dolostone; 145-168 m.
Lower member: brown dolostone with minor
anhydrite; 23-53 m.
Contacts between the members are gradational. Palynological results reported by McGregor and Camfield (1976)
suggest an Upper Silurian or Lower Devonian age for the
upper part of the middle member and a Lower Devonian
(Gedinnian-Siegenian) age for the upper member.
All three members, generally conforming to the above
descriptions, were identified in a drillhole at Schlievert Lake
in the south-central Moose River Basin (Russell et al.,
1985). The lower member was unusually thin (6.4 m) and the
lower half was slightly silty and shaly, grading downward
into the regolith of weathered Precambrian rock. This supports the interpretation that Paleozoic sedimentation in the
central and eastern parts of the basin was entirely postEarly Silurian.
Red beds characteristic of the middle member are best
exposed in a small uplifted fault block on the southern
margin of the basin near Coal Creek, a tributary of the
Missinaibi River. Outcrops of the upper member occur
along the Albany River and its major tributary, the Kenogami River in the west-central part of the basin. The type
section of the upper member is a composite sequence
exposed in the Albany River delta (Sanford and Norris,
1975).
Although they have only been observed in drill core,
contacts of the Kenogami River Formation with overlying
elastics of the Sextant Formation or fossiliferous limestones
of the Stooping River Formation are distinct. Stoakes (1978)
described the lateral facies relationships among these three
units, with the supratidal upper member of the Kenogami
River Formation deposited contemporaneously, in part,
—
with the other formations during the initial Lower Devonian transgression of the Moose River Basin.
SEXTANT FORMATION
Savage and Van Tuyl (1919) introduced the name Sextant sandstone and shale for clastic beds exposed along the
Abitibi River in the vicinity of Sextant Rapids. Since then
the unit has been examined by numerous workers, with the
most complete description provided by Sanford and Norris
(1975). The formation is mainly reddish arkosic sandstone,
but also includes varicolored conglomerates, siltstones,
shales and clays, with a maximum known thickness of about
90 m. Additional exposures of these clastic units have been
reported at several localities around the southeastern margin of the Moose River Basin. Some are of problematical
Devonian Moose e R . Basin , Canad
age and at least one (in Adam Creek, south of the Mattagami River; reported but not seen by Sanford and Norris,
1975, p. 35) is now known to be an unusually lithified
horizon within the Lower Cretaceous Mattagami Formation. However, the Sextant Formation does appear to be
restricted to a narrow zone around the basin margin.
Well preserved plant remains occur in various horizons,
and particularly in micaceous shale lenses within the lower
part of the formation in the Abitibi River outcrops. They
have been described by W.A. Bell (in Martison, 1953),
Lemon (1953), and Hueber (1983) and are one of only a few
occurrences in the world of Lower Devonian land floras.
Taxa include the trimerophyte Psilophyton dawsonii,
zosterophyte Sawdonia ornata, and lycopods Drepanophycus spinaeformis and Baragwanathia abitibiensis.
Palynological evidence reported by McGregor and Camfield (1976) indicates a middle to upper Emsian age for the
formation.
The clastic beds of the Sextant Formation are overlapped by, and merge northwestward with marine carbonates
of the Stooping River Formation. There may also be a
lateral facies relationship with the Kenogami River Formation (upper member). In the Schlievert Lake drill hole (Russell et al., 1985) the lower few metres of the Stooping River
Formation contain silty dolostones and thin sandstone
lenses which perhaps represent a far offshore facies of the
Sextant Formation elastics. As noted previously, Stoakes
(1978) suggested that elastics of the Sextant Formation were
deposited partly in a marine environment by reworking of
coastal sediments derived from erosion of the adjacent Precambrian uplands. Subsequent authors (e.g., Norris, 1986;
Sanford, in press) have continued to refer to the unit as a
nonmarine or continental facies. The occurrence of elastics
in the Schlievert Lake drill hole possibly related to the
Sextant Formation, and the gradational lateral boundary
between the Sextant and Stooping River Formations (and
the Kenogami River Formation), imply that the Sextant
Formation is unlikely to be an exclusively continental facies.
STOOPING RIVER FORMATION
The name Stooping River Formation was proposed by
Sanford et al. (1968) for Lower Devonian limestones and
dolostones outcropping near the junction of the Albany and
Stooping Rivers. As deposits of this unit (and its lateral
equivalent, the Sextant Formation) form the major part of
the initial Lower Devonian transgressive sequence in the
Moose River Basin, these strata lie on a variety of substrates, including Precambrian basement rocks and
Ordovician and Silurian dolostones.
The Stooping River Formation consists generally of
nodular or thin bedded cherty limestone with minor dolomitic limestone and dolostone. Some beds are extremely
fossiliferous, with a diverse shelly fauna. Outcrops of the
unit are widespread in a belt extending around the basin
from the Albany River delta in the north to the Abitibi and
127
Mattagami Rivers in the southeast. Thickness is variable,
being usually less than 50 m but ranging up to 143 m in the
Jaab Lake (Sanford and Norris, 1975) and Schlievert Lake
(Russell et al., 1985) drill holes.
Conodonts obtained from the upper two-thirds of the
formation, although not strongly diagnostic, suggest an
Emsian age for this interval (Uyeno, in Sanford and Norris,
1975). Palynological results reported by McGregor and
Camfield (1976) indicate a possible Siegenian age at the base
to upper Emsian at the top of the formation. In general, the
megafossil and microfossil assemblages of the Stooping
River Formation have much in common with faunas of the
Schoharie, Bois Blanc and lower Onondaga Formations of
the Appalachian Basin.
Carbonates of the Stooping River Formation were
formed in intertidal or shallow subtidal environments. They
represent the establishment of fully marine conditions over
the Moose River Basin as a result of Lower Devonian transgression.
KWATABOAHEGAN FORMATION
This unit consists of massive to thick bedded biohermal
and biostromal limestones that are well developed in the
central and southeastern Moose River Basin. The name
Kwataboahegan was introduced and defined by Sanford et
al. (1968) to replace Martison's (1953) Upper Abitibi River
Formation and to resolve the problem caused by Martison
having placed the unit stratigraphically above the younger
Moose River Formation (his Middle Abitibi River Formation). Exposures of the unit at Coral Rapids, on the Abitibi
River, were selected as the type section (Sanford et al.,
1968). The best outcrops of the unit are those at Coral
Rapids and Grand Rapids, on the Mattagami River, where
limestone cliffs rise 15 m above water level and extend for
several kilometres along both sides of the river. Stratigraphic thickness ses of strata referred to the
Kwataboahegan Formation range from 24 to 77 m, this
variation presumably due to the biohermal-biostromal
nature of the unit.
Carbonate buildups of this formation appear to be
associated with topographic highs produced by relief on the
Precambrian basement surface. Outcrops on the Mattagami River noted above overlie a feature known as the
Grand Rapids Arch. Away from the highs the unit is thinner
bedded, bituminous and less fossiliferous and is difficult to
distinguish from the supposedly underlying Stooping River
Formation or overlying Moose River Formation.
Strata of the Kwataboahegan Formation are the most
fossiliferous of all Devonian units in the Moose River Basin.
The fauna is dominated by corals, stromatoporoids and
brachiopods and also includes a diverse assemblage of other
invertebrates. In a preliminary description of the fauna
Sanford and Norris (1975, p. 45-48) list 25 coral species,
about 30 brachiopod species and more than 35 other invertebrate taxa. The coral and brachiopod assemblages have
many elements in common with the Schoharie-Bois Blanc128
Onondaga faunas of the Appalachian Basin and those of
the Michigan Basin Detroit River Group. This is in marked
similarity to the Stooping River Formation and points to the
possible partial contemporaneity of the two Moose River
Basin lithostratigraphic units.
Conodont faunas obtained from the lower part of the
formation (Uyeno, in Sanford and Norris, 1975) also are
similar to those from the Stooping River Formation and
have a probable Emsian age. Both corals and conodonts
recorded from the upper part of the Kwataboahegan Formation are slightly younger than taxa in the Stooping River
Formation, but may be correlative with sparse faunas in the
Moose River Formation. This may also confirm at least
partial contemporaneity of the Kwataboahegan carbonate
build-ups and Moose River lagoonal or back-reef facies
(see below).
MOOSE RIVER FORMATION
The name Moose River Formation was introduced by
Dyer (1928) but removed by Martison (1953) in favor of the
term Middle Abitibi River Formation. Sanford et al. (1968)
and Sanford and Norris (1975) eliminated the impreciseness
of the terminology and reintroduced Moose River Formation, defining the unit as the evaporitic and brecciated carbonates overlying the Kwataboahegan Formation and
underlying the Murray Island Formation.
Strata of the Moose River Formation are well exposed
along the Abitibi, Moose and Cheepash Rivers in the eastern part of the basin. Representative sections through the
unit were intersected in the recent Ontario Geological Survey drill holes at Schlievert Lake (Russell et al., 1985) and
Onakawana (Sanderson and Telford, 1985). The unit consists mainly of unfossiliferous to poorly fossiliferous limestone, dolostone, brecciated carbonates, gypsum and minor
anhydrite. Spectacular cliffs of white gypsum form the west
bank of the Moose River for several kilometres downstream
from the railway bridge at Moose River Crossing. Commonly however, the gypsum has been removed by dissolution (e.g. Schlievert Lake drillhole) leading to increased
collapse and brecciation of surrounding carbonates. Also,
because of this effect, thickness of the unit varies widely
from about 28 to 90 m. In the Onakawana B drillhole the
Moose River Formation is about 48 m thick and rests
directly on Precambrian basement rocks.
Stoakes (1978) interpreted much of the Moose River
Formation to be a lagoonal facies developed between the
carbonate buildups of the Kwataboahegan Formation.
Although this may be partially correct, the strata of the
Moose River Formation extend well beyond the known
range of Kwataboahegan deposits, and a variety of other
,
carbonate facies are represented. . Nevertheless the
lithologies of the Moose River Formation do suggest a
regressive phase, when the open platform marine conditions
that allowed deposition o f the Stooping RiverKwataboahegan carbonates became restricted and environments conducive to evaporitic deposition were developed.
Telford
MURRAY ISLAND FORMATION
The Murray Island Formation is a thin sequence of
fossiliferous limestones which succeed disconformably the
evaporites and associated carbonates of the Moose River
Formation and are overlain with probable disconformity by
the Williams Island Formation. The limestones represent
return to open marine conditions in the basin. The unit was
first defined by Sanford et al. (1968). Previous workers
(e.g., Dyer, 1928; Martison, 1953) had described these strata
but none had recognized them as a discrete rock unit.
Outcrops of the unit only occur in the southeastern part
of the basin, especially on the Abitibi River and along the
Moose River near Moose River Crossing. In its type area
near Moose River Crossing (Sanford and Norris, 1975), the
unit consists of fossiliferous calcarenite and highly calcareous dolostone. The beds are generally closely jointed
and fractured, and can be brecciated due to solution collapse of underlying evaporitic beds of the Moose River
Formation.
Thickness of the unit varies from 6 to 20 m. In the
Schlievert Lake drill hole lithologies typical of the Murray
Island Formation are absent, possibly because of erosion
preceding deposition of the younger Williams Island Formation.
Brachiopods are relatively abundant and well preserved
in the limestone beds of the formation. Norris (1986) indicates that the faunal assemblages have elements in common
with the Onondaga Formation (Appalachian Basin), Dun-
a
dee Formation (Michigan Basin) and Elm Point Formation
(Williston Basin), as well as the Cordilleran Faunal
Province of northwestern Canada. The limestones also
yielded abundant conodonts indicative of an upper Eifelian
age (Uyeno, in Sanford and Norris, 1975).
WILLIAMS ISLAND FORMATION
Kindle (1924) proposed the name Williams Island Formation for a sequence of shale and carbonates exposed
around Williams Island and along the adjacent banks of the
Abitibi River, near the eastern margin of the Moose River
Basin. The formation contains a complex variety of
lithological units and was divided into two members by
Sanford and Norris (1975). The lower member is dominantly grey shale with soft sandstone, gypsiferous shale,
gypsiferous siltstone and sandstone, soft limestone and
some brecciated limestone. At some localities basal beds of
the member consist of reddish calcareous shale with a well
preserved brachiopod fauna. The lower member is 36 to 47
m in thickness.
The upper member consists of thin to medium bedded
argillaceous limestone and calcareous shale, dolomitic
limestone, oolitic limestone and zones of brecciated and
vuggy limestone and dolostone. A limestone bed in the
middle part of the member at
Island contains a
rich coral fauna. The upper member is 33 to 45 m in thickness .
Devonian Moos e R . Basi , Cana
Williams
Outcrops of the Williams Island Formation are
restricted to the eastern part of the basin and are found only
along the Abitibi, Moose and Little Abitibi Rivers.
The recessive nature of the shaly lower member also
precludes extensive exposure. Complete sections through
the formation were intersected in the Schlievert Lake and
Onakawana B drillholes. In the former the lower member
and lower part of the upper member were intensely brecciated, probably as a result of removal of evaporites from the
underlying Moose River Formation.
During field studies by the Ontario Geological Survey in
late 1984, at a time of unusually low river levels, the upper
contact of the Williams Island Formation with the Long
Rapids Formation was observed on the east bank of the
Abitibi River adjacent to the type section on Williams
Island (Russell and Telford, 1984). The contact is sharp and
disconformable, with the upper part of the Williams Island
Formation consisting of thick bedded, fractured and brecciated, unfossiliferous, vuggy limestone.
Brachiopod-coral assemblages from the lower member
of the formation are very similar to faunas from the Hamilton Group of the Appalachian Basin (New York State) and
Michigan Basin (southwestern Ontario), which are dated as
upper Middle Devonian (Givetian) (Norris, 1986). The coral
fauna from the upper member has elements in common with
the Traverse Group of the Michigan Basin, also dated as
Givetian.
As discussed by Sanford and Norris (1975), clastic beds
in the lower member reflect uplift and erosion of highland
areas around the basin margin. Supratidal conditions probably prevailed within the basin. Localized or restricted
occurrences of marine fossils within both members suggest
only intermittent intervals of subtidal conditions.
LONG RAPIDS FORMATION
The Long Rapids Formation is the lithostratigraphic
equivalent of the extensive Upper Devonian organic-rich
black shale facies of eastern North America, which is represented in the Michigan Basin by the Antrim Shale (Michigan) and Kettle Point Formation (southwestern Ontario)
and in the Appalachian Basin by the Ohio Shale and other
units (Janka and Dennison, 1980). Recent interest in the
hydrocarbon content of these black shales has prompted
increased attention to the stratigraphy and oil shale poten-
tial of the Long Rapids Formation. Preliminary samples
from outcrops of the formation had organic carbon contents of greater than 10% , which is roughly equivalent to a
Fischer Assay oil yield of greater than 45 litres/tonne (Russell and Telford, 1984).
The name Long Rapids Shale was introduced by Savage
and Van Tuyl (1919) for Upper Devonian shales exposed
along the Abitibi River near Long Rapids and Williams
Island, close to the eastern margin of the Moose River Basin
(Fig. 1). In the type area the unit disconformably overlies the
upper carbonate member of the Williams Island Formation.
The Long Rapids Formation is the youngest Paleozoic unit
129
in the Moose River Basin and is disconformably overlain by
unconsolidated clastic Mesozoic sediments of continental
origin. Because of its recessive nature the unit is poorly
exposed and outcrops have been observed only in the type
area along the Abitibi River and at Grand Rapids on the
Mattagami River.
Current work by the Ontario Geological Survey has
shown that the subsurface distribution of the Long Rapids
Formation is restricted to a much smaller area (Fig. 1) than
shown by Sanford and Norris (1975).
The thickest reported sections of the Long Rapids Formation in the Moose River Basin occur in the Onakawana
A/Onakawana B drillholes, viz.
Onakawana A: 87 m (Dyer and Crozier, 1933).
Onakawana B: 79.3 m (Sanderson and Telford, 1985).
The discrepancy is probably due to differing interpretations of the upper and lower boundaries of the unit. Dyer
and Crozier (1933) divided the formation informally into
three members. This lithological subdivision was confirmed
in Onakawana B and partly in the type area on the Abitibi
River where the lower two members are represented in an
approximate 48 m section.
The lower member (about 36 m) consists of green-grey
mudstone and shale alternating with fissile black shale and
frequent concretionary carbonate layers. The middle member (about 29 m) is mainly black fissile shale while the upper
member (15-20 m) is poorly consolidated green-grey clay
and grey shale.
The general characteristics (thickness, lithology, faunal
content including trace fossils) of the green-grey mudstones
and carbonates in the type section and Onakawana B drillhole suggest deposition in relatively shallow water. The
interbedding of these facies with the black shales implies a
similar shallow water depth for these rocks, with deposition
of the black, organic rich sediments being accomplished by
elevation of the pycnocline relative to the sediment/water
interface rather than deepening of the basin. Russell (1985)
proposed a similar depositional environment for the black
shales of the Upper Devonian Kettle Point Formation in
southwestern Ontario. Beds tentatively assigned to the
Long Rapids Formation in the Hudson Bay Basin consist of
evaporitic mudstone and reddish siltstone and sandstone
(Norris, 1986), indicating regressive conditions and giving
some support to the interpretation of restricted water circulation and shallow water deposition in the adjoining
Moose River Basin.
The biostratigraphy of the Long Rapids Formation is of
particular interest. A goniatite bed, first reported by Savage
and Van Tuyl (1919), was rediscovered in the Abitibi River
type section during the 1984 Ontario Geological Survey field
program (Russell and Telford, 1984) and contains the species Manticoceras cf. sinuosum. This goniatite also occurs
in the Cashaqua Shale of New York State which has been
assigned to the conodont Ancyrognathus triangularis Zone
of mid-Frasnian age (Norris, 1986).
Brachiopod faunas are diverse and well preserved in the
130
Telford
lower part of the formation. Some twenty species have been
identified, the most significant being Ladogioides pax,
Leiorhynchus cf. quadracostatum, and Tecnocyrtina cf.
missouriensis from the basal beds, and Calvinaria cf. variabilis athabascensis from higher in the section, several
metres above the goniatite bed. Well preserved conodonts
have been extracted in abundance from the carbonate horizons with the brachiopod faunas and have also been
observed on black shale bedding surfaces. Species from the
basal beds accompanying the above-noted brachiopods are
characteristic of the latest Givetian lowermost asymmetricus Zone. From higher in the formation species representing at least six of the standard Upper Devonian
conodont zones, ranging from the earliest Frasnian Lower
asymmetricus Zone to the middle Famennian Lower rhomboidea Zone, have been identified. Preliminary analysis of
the faunas (by the author, with T.T. Uyeno and A.W.
Norris, Geological Survey of Canada) suggests that the
Long Rapids Formation spans most of the Upper Devonian, with the Middle-Upper Devonian boundary located
near the base of the unit, and the Frasnian-Famennian
boundary lying only 35-40 m stratigraphically higher.
INTERBASINAL RELATIONSHIPS
The Devonian succession in the Moose River Basin is
very similar to that of the adjoining Hudson Bay Basin and
there was close connection between the basins throughout
most of the period. Nevertheless some important differences occur. Thickness of the Devonian strata in the
Hudson Bay Basin is almost 600 metres, about 50% greater
than the Moose River Basin. Clastic deposits similar to
Devonian, Moose R. Basin, Canada
those of the Sextant Formation have not been reported from
the Hudson Bay Basin. In the central part of the basin the
evaporitic Moose River Formation is about double the
thickness of the unit in the Moose River Basin. Finally, beds
in the Hudson Bay Basin considered equivalent to the Long
Rapids Formation consist of evaporitic and coarse clastic
lithologies, as opposed to the marine carbonates and black
shales in the Moose River Basin. Many of the differing
features would seem to suggest that the Hudson Bay Basin
was more isolated at particular times than the Moose River
Basin and suffered more severely from the regressive
epeirogenic episodes that produced supratidal and evaporitic depositional conditions.
At present, rocks of the Moose River Basin (and Hudson Bay Basin) are separated from sequences in other North
American Paleozoic sedimentary basins by large tracts of
the Canadian Shield (Fig. 3). However, lithological and
biostratigraphical similarities of the Devonian succession
described herein with sequences in the distant Williston,
Michigan, and Appalachian Basins (Fig. 3) suggest periodic
interconnection of seaways across the Shield during Devonian time.
The Lower Devonian units of the Moose River Basin
(except for the clastic Sextant Formation, which is a local
development) are very similar lithologically, faunally, and
in their succession to sequences in the Appalachian and
Michigan Basins of southern Ontario and neighboring U.S.
states. Close correlation of megafaunal elements with those
of the Appalachian Basin was noted by Sanford and Norris
(1975) and Norris (1986). Also, conodont faunas reported
from the Lower Devonian units of the Moose River Basin
(Uyeno, in Sanford and Norris, 1975) are virtually identical
to those described from southwestern Ontario (Uyeno et al.,
1982).
The evaporitic Moose River Formation is similar in
depositional character and stratigraphic location to the
Middle Devonian Lucas Formation of the Detroit River
Group in the central Michigan Basin. The overlying Murray
Island Formation is lithologically and faunally similar to
the Dundee Formation of the Michigan Basin and has
brachiopod faunal elements in common with the Elm Point
Formation of the Williston Basin in southern Manitoba
(Norris, 1986).
Black shales of the Long Rapids Formation in the
Moose River Basin represent the most northern extent of the
eastern North American Upper Devonian black shale
province that was centred in the Appalachian Basin. The
lack of these black shales in the Hudson Bay Basin suggests
that, by mid-Frasnian time the seaway connecting the
Moose River Basin to the southeast may have terminated
south of the Cape Henrietta Maria Arch, and that the
Hudson Bay Basin was isolated or only connected to the
Williston Basin in the southwest.
Faunas from the Lower and lower Middle Devonian
units of the Moose River Basin have elements in common
with sequences in only the southeast, i.e., the Michigan and
131
Appalachian Basins. However, assemblages from younger
units (Murray Island to lower Long Rapids Formations)
display similarities also with Midcontinent and Cordilleran
faunas (Norris, 1986). This implies that, during the Early
Devonian seaway connections to the Moose River and Hudson Bay Basins were only from the Michigan and
Appalachian Basins in the southeast but, by late Middle
Devonian, a connection was also established from the west
or southwest, allowing mixing of faunas in the Moose River
Basin. This is consistent with the increased inundation of
the North American craton beginning in the late Middle
Devonian and the overall cosmopolitanism of upper Middle
and Upper Devonian faunas.
Following regression in latest Devonian, and severing of
the seaway connections the Moose River Basin has since
remained isolated.
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