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| Titel |
Review of geology of the New Siberian Islands between the Laptev and the East Siberian Seas, North East Russia |
| VerfasserIn |
M. Kos'ko, E. Korago |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1868-4556
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| Digitales Dokument |
URL |
| Erschienen |
In: Geology, geophysics and tectonics of Northeastern Russia: a tribute to Leonid Parfenov ; Nr. 4 (2009-09-17), S.45-64 |
| Datensatznummer |
250001438
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| Publikation (Nr.) |
 copernicus.org/smsps-4-45-2009.pdf |
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| Zusammenfassung |
The New Siberian Islands comprise De Long Islands, Anjou Islands, and Lyakhov
Islands. Early Paleozoic, Mesozoic and Cenozoic sediments and igneous rocks
are known on the De Long Islands. Cambrian slate, siltstone, mudstone and
silicified limestone occur on Bennett Island. Ordovician volcanogenic
turbidites, lavas, and small intrusions of andesite-basalt, basalt, dolerite,
and porphyritic diorite were mapped on Henrietta Island. The igneous rocks
are of calc-alkaline island arc series. The Ordovician age of the sequence
was defined radiometrically. Early Paleozoic strata were faulted and folded
presumably in the Caledonian time. Early Cretaceous sandstone and mudstone
are known on Bennett Island. They are overlain by a 106–124 Ma basalt unit.
Cenozoic volcanics are widespread on the De Long Islands. Zhokhov Island is
an eroded stratovolcano. The volcanics are mostly of picrite-olivine type and
limburgite. Radiometric dating indicates Miocene to Recent ages for Cenozoic
volcanism.
On the Anjou islands Lower-Middle Paleozoic strata consist of carbonates,
siliciclastics, and clay. A Northwest-southeast syn-sedimentary facies
zonation has been reconstructed. Upper Paleozoic strata are marine carbonate,
clay and siliciclastic facies. Mudstone and clay predominate in the Triassic
to Upper Jurassic section. Aptian-Albian coal bearing deposits uconformably
overlap lower strata indicating Early Cretaceous tectonism. Upper Cretaceous
units are mostly clay and siltstone with brown coal strata resting on Early
Cretaceous weathered rhyolite. Cenozoic marine and nonmarine silisiclastics
and clay rest upon the older units with a transgressive unconformity
including a weathering profile in the older rocks.
Manifestations of Paleozoic and Triassic mafic and Cretaceous acidic
magmatism are also found on these islands. The pre-Cretaceous structure of
the Anjou islands is of a block and fold type Late Cimmerian in age followed
by faulting in Cenozoic time.
The Lyakhov islands are located at the western end of the Late Cimmerian
South Anyui suture. Sequences of variable age, composition, and structural
styles are known on the Lyakhov Islands. These include an ancient metamorphic
sequence, Late Paleozoic ophiolitic sequence, Late Mesozoic turbidite
sequence, Cretaceous granites, and Cenozoic sediments. Fold and thrust
imbricate structures have been mapped on southern Bol'shoi Lyakhov Island.
North-northwestern vergent thrusts transect the Island and project offshore.
Open folds of Jurassic–Early Cretaceous strata are characteristic of
Stolbovoi and Malyi Lyakhov islands.
Geology of the New Siberian Islands supports the concept of a circum Arctic
Phanerozoic fold belt. The belt is comprised of Caledonian, Ellesmerian,
Early Cimmerian and Late Cimmerian fold systems, manifested in many places on
the mainland and on islands around the Arctic Ocean. Knowledge of the geology
of the New Siberian Islands has been used to interpret anomalous gravity and
magnetic field maps and Multi Channel Seismic (MCS) lines. Two distinguishing
structural stages are universally recognized within the offshore sedimentary
cover which correlate with the onshore geology of the New Siberian Islands.
Dating of the upper structural stage and constituent seismic units is based
on structural and stratigraphic relationships between Late Mesozoic and
Cenozoic units in the archipelago. The Laptev Sea–western East Siberian Sea
seismostratigraphic model for the upper structural stage has much in common
with the seismostratigraphic model in the American Chukchi Sea. |
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