Sample Ltd. Carbonates Cambridge

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CONFIDENTIAL
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Multiclient Report for
2011
Peter Gutteridge
Late Palaeozoic Sedimentology of 7128/6-1
Volume 2
Contents
CORE 24: BASEMENT (AGE UNCERTAIN) ................................................................ 5
2.
CORE 23: BRIGANTIAN (BILLEFJORDEN GROUP, NORDKAPP FORMATION) .......... 6
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1.
Fine-grained argillaceous sandstone facies .................................................... 6
2.2.
Medium-grained quartzite facies .................................................................... 7
2.3.
Coarse-grained arkose facies .......................................................................... 7
2.4.
Heterolithic facies ........................................................................................... 8
2.5.
Provenance of sandstones .............................................................................. 8
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2.1.
3.
BASE CORE 22 TO 2103M: GZELIAN -SERPUHOVIAN, (KAPP KåRE FORMATION,
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GIPSDALEN GROUP) ....................................................................................................... 9
Bioclastic sandstone / quartzose limestone facies ......................................... 9
3.2.
Medium- to coarse-grained sandstone facies............................................... 10
3.3.
Wackestone/boundstone facies ................................................................... 10
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3.1.
CORE 21 2103m TO 2075m: SAKMARIAN - ASSELIAN (KAPP HANNA FORMATION,
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4.
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GIPSDALEN GROUP) ..................................................................................................... 13
Silty shale/argillaceous siltstone facies ......................................................... 13
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4.1.
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4.2.
5.
Bioclast packstone/grainstone facies............................................................ 13
4.3.
Medium-grained sandstone facies ................................................................ 14
4.4.
Palaeoaplysina/phylloid algal boundstone facies ......................................... 15
CORE 21 2075M – CORE 18 2022M: ARTINSKIAN - ? SAKMARIAN (KAPP HANNA
FORMATION, GIPSDALEN GROUP)............................................................................... 16
5.1.
Argillaceous wackestone/packstone facies .................................................. 16
Late Palaeozoic sedimentology: 7128/6-1 volume 2
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5.2.
Fine- to medium-grained sandstone facies................................................... 17
5.3.
Anhydritic dolomite facies ............................................................................ 17
6.
CORE 18 2022M – CORE 13 1868M: SAKMARIAN - ASSELIAN (KAPP DUNER
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FORMATION, GISPDALEN GROUP)............................................................................... 19
Stromatolitic bindstone facies ...................................................................... 19
6.2.
Dolomitised mudstone/wackestone facies ................................................... 19
6.3.
Fine- to medium-grained sandstone facies................................................... 20
6.4.
Argillaceous bioclast wackestone ................................................................. 21
6.5.
Bioclastic packstone/grainstone facies ......................................................... 22
6.6.
Palaeoaplysina boundstone facies ................................................................ 24
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CORE 13 1868M - 1840.75M: SAKMARIAN - ASSELIAN (HAMBERGFYELLET
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6.1.
fORMATION, GIPSDALEN GROUP) ............................................................................... 25
Bioclastic shale facies .................................................................................... 25
7.2.
Medium to coarse grained sandstone facies ................................................ 25
7.3.
Graded bioclast packstone facies.................................................................. 26
7.4.
Sorted crinoidal grainstone facies ................................................................. 27
7.5.
Bioclast wackestone/packstone facies.......................................................... 28
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7.1.
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7.6.
8.
Contact between the Hambergfjellet Formation and Tempelfjorden Group
28
CORE 9 1746.50M TO TOP CORE 6: TATRIAN - ? kUNGURIAN (‘BLACK LIMESTONE
UNIT’, TEMPELFJORDEN GROUP) ................................................................................ 30
9.
CORES 3, 2 & 1: TATARIAN - ? KUNGURIAN (‘SPICULITIC LIMESTONE UNIT’
TEMPELFJORDEN GROUP) ........................................................................................... 33
Late Palaeozoic sedimentology: 7128/6-1 volume 2
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Appendix 1: CORE LOGS .................................................................................... 35
11.
Appendix 2: MICROFACIES DATA ...................................................................... 48
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10.
Late Palaeozoic sedimentology: 7128/6-1 volume 2
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Microfacies: This bioclast grainstone/ packstone that contains disarticulated,
fragmented and abraded bioclasts. Intraclasts of bioclast wackestone/packstone and
silty shale with comminuted bioclasts are also present. Glauconite peloids and
glauconite infills of intragranular porosity within allochems are common. Siliciclastic
sand-sized grains are present in trace amounts throughout this microfacies. The
concentrated at some intervals. Bioclasts are occasionally partly coated by
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majority of allochems have not been micritised but partially micritised grains are
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Tubiphytes. Allochems commonly show a random alignment. Occasional intervals are
replaced by dolomite; replacive anhydrite nodules are also present within the
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dolomite.
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Interpretation: The varying degree of fragmentation of bioclasts suggests that they
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have undergone a varied degree of reworking. The occurrence of in situ corals
suggests that sedimentation was episodic with periods of slow sedimentation during
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which corals could grow. This facies is interpreted as redeposited bioclastic
limestones, probably representing storm deposits, which were reworked from a
shallow subtidal environment and redeposited close to, or just below normal wave
base.
Medium-grained sandstone facies
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4.3.
Core: This is a moderate to well-sorted fine- to medium-grained sandstone 0.5-2.5m
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in thickness which shows intensive bioturbation (Plates 22 and 57). Sedimentary
structures are thus rare although, ripple-lamination has been preserved in some
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intervals. Occasional disarticulated and fragmented bioclasts including brachiopod
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shells, crinoid ossicles and rare well-rounded quartzite pebbles are present.
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Microfacies: This is a clean, moderately sorted, fine to coarse grained
subarkose/quartz arenite with moderate to highly spherical, rounded to subrounded grains. Disarticulated, fragmented and abraded bioclasts are also present.
Lithic clasts include well-sorted, very fine-grained quartz arenite and sandy siltstone.
Late Palaeozoic sedimentology: 7128/6-1 volume 2
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are interpreted as the result of occasional winnowing (possibly as a result of storm
activity). The well-sorted bioclast grainstone/packstone cross-bedding and scours
implies prolonged reworking in a high energy environment above normal wave base.
Teepee structures imply that this environment was subjected to desiccation and the
laminated micritic crusts are interpreted as calcrete features, some of which have
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been reworked. The episodes of emergence within this facies suggests that the
overall setting was a shallow marine carbonate sand body which included shallow
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subtidal, shore face and emergent barrier environments. Graded bioclast intraclast
Palaeoaplysina boundstone facies
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reworking.
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grainstone are interpreted as resedimented limestones generated by storm
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The Palaeoaplysina facies association is described in detail in Volume 1, section 4.
Late Palaeozoic sedimentology: 7128/6-1 volume 2
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this random fabric. Some spicules occur in burrows which have penetrated the
sediment.
Interpretation: The silicification appears to have taken place in at least two stages:
the pervasive replacement of the matrix by microcrystalline silica was followed by
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remobilsation of the silica to form the chert nodules. The silica was probably derived
from the abundant sponge spicules (all of which are preserved as moulds). Some
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moulds show an incomplete lining of microcrystalline silica cement.
The very fine-grained nature of this facies together with the common occurrence of
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in situ sponges suggests deposition in a low energy environment. The presence of
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winnowed layers of disarticulated shells implies occasional episodes of winnowing,
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possibly by storm activity. This may indicate deposition below normal wave base but
above storm wave base. The intensive bioturbation together with common bored
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bioclasts indicates oxygenated bottom conditions and generally slow sedimentation.
The abundance of sponge spicules suggest that there was a very dense colonization
of the sea floor by sponges, possibly forming an almost continuous sponge mat with
occasional in situ tabular or rounded sponges. Some whole brachiopod and mollusc
shells may have been living in this environment. Layers of fragmented and rounded
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shells are interpreted as periodic winnowing, possibly by storm activity. The graded
layers of comminuted bioclastic calcisiltite and quartz silt are interpreted as distal
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turbidites. This suggests that the depositional setting was a low energy environment
but subject to occasional reworking. The common occurrence of random or swirl
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alignment of spicules indicates an intensive bioturbation of the sediment which, in
turn, implies well-oxygenated bottom conditions. Some winnowed and graded layers
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have been incorporated into the sediment by bioturbation. Burrows infilled by
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spicules are interpreted as Thalassinoides.
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