The North Kara Basin: Geological Structure and Hydrocarbon Systems

Valeriy Nikishin

The area of the North Kara Basin (NKB) is covered by a 16,000 km line of 2D seismic study. No wells were drilled there. The NKB is characterized of rift and post-rift activity. There are several rift troughs in the NKB: Uedinenia (UT), Priseverozemelskiy (PT), Urvantsev (UrT) and Krasnoarmeiskiy (KT). Most of them are bounded by normal faults with a displacement shift from 2 to 6 km. The united UT and PT troughs are 350 km long and 50 km wide. When viewed in plan view they form an arch shape near the Taymir Peninsula. Troughs are separated by Nalivkin Megaswell (NM). The NKB is bounded on the south-east by the Bolshevik thrust belt formed during the Late Paleozoic. This thrust belt was also reactivated during the Mesozoic and Cenozoic. On the south NKB bounded by North-Siberian Megaswell. The Ermolaeva Saddle is bounded by a normal fault on the west. Overall, this saddle and Ushakov-Vize Megaswell divide the North Barents and the NKB. Several seismic complexes are identified in the basin: (1) synrift (Early Ordovician), (2) post-rift (Middle Ordovician to Early Devonian), (3) distal molasse (Mid-Late Devonian), and (4) post-inversion (Carboniferous to Cenozoic). We used the Severnaya Zemlya (SZ) stratigraphy for stratification of the NKB. The acoustic basement possibly consists of strata from the Neoproterozoic to Cambrian and maybe older. Low Ordovician compiles clastic succession with possible volcanoclactics. The UrT in the northern part of the NKB is filled by the Ordovician-Devonian sequence with some big salt diapirs and pillows. We linked these salt bodies with the Ozerninskaya Fm (O2) evaporates on SZ and dated them as Middle Ordovician. The Late Ordovician Age is not excluded based on the information of Timan-Pechora Basin (TPB) evaporate dating. The Silurian deposits compile a large carbonate platform with large carbonate build-ups characterized by different facies. The Devonian succession are carbonates to clastics. Middle- Upper Devonian is classic Old Red sandstone formation. The Carboniferous-Permian deposits are molasses. The Ordovician rifting in the NKB took place in back-arc tectonic environments. Similar events took place in the TPB. Inversion structures are typical for the NKB. The biggest one is the NM. The main inversion tectonics took place close to the Devonian-Carboniferous transition. At the same time, inversion movements took place between the Ordovician and Silurian, between the Silurian and Devonian and between the Early and Middle Devonian.

AAPG Search and Discovery Article #90177©3P Arctic, Polar Petroleum Potential Conference & Exhibition, Stavanger, Norway, October 15-18, 2013