Permo-Triassic volcanics of the Koltogory-Urengoi rift of the West Siberian geosyneclise

Abstract

The lithologic composition of basalts from the most complex sections of the Koltogory-Urengoi Rift is considered, and their 40Ar/39Ar ages are given: basalts from the lower section of Nikol’skaya BH-1 (Bergamak Formation) — 272.9 ± 10.5 and 249.5 ± 3.0 Ma, basalts from the uppermost section (Voinov Formation) — 247.5 ± 2.9 Ma, and basalts from the lower section of Tyumenskaya SDB-6 (Korotchaevo Formation) — 251.2 ± 2.0 Ma. According to these and the paleomagnetic data, trap magmatism began in the Koltogory-Urengoi Rift in the Permian and ended in the Early Triassic, whereas the paleontological data suggest its beginning in the Early Triassic and its termination in the late Middle Triassic. In Tyumenskaya SDB-6 we have recognized both low-K tholeiitic and medium- to high-K subalkalic and calc-alkalic basalts, which form large alternating packets up to 480 m thick. This section is juxtaposed to the anomalous sections of the Siberian Platform trap formation near the margins of the Tunguska syneclise. The section of Nikol’skaya BH-1 is composed mainly of medium- and high-K subalkaline basalts with scarce flows of low-K ones. The low-K basalts differ from the medium- and high-K varieties in having lower contents of TiO2, P2O5, Ba, Rb, Th, and ΣLREE. The Tyumenskaya SDB-6 basalts are characterized by paleohypergene alterations, up to the development of more than five levels of alumina-ferruginous cuirasses, as well as superposed chloritization, sericitization (hydromication), carbonatization, zeolitization, silicification, and epidotization, whereas the Nikol’skaya BH-1 basalts are subjected mainly to carbonatization, chloritization, and hydromication. We have concluded that the existence of a vast mega-arch above the superplume within the West Siberian geosyneclise in the Permo-Triassic was complicated by the Koltogory-Urengoi Rift. The Triassic rift deposits are both continental and marine sediments (sandstones and siltstones with glauconite, coccolith oozes, spherulitic lavas, and hyaloclastites). The basic volcanism within the rift showed the features of both rift and flood basalts as well as E-MORB.

Evolution of the provenances of Triassic rocks in Franz Josef Land: U/Pb LA-ICP-MS dating of the detrital zircon from Well Severnaya

“…Zircon of the age interval from 370 to 300 Ma and, possibly, to 270 Ma is related to the Hercynian (Uralian) magma tism, the manifestations of which are known in the Polar Urals and Taimyr (Zonenshain et al, 1990;Brown et al, 2006;Pease, 2011). The youngest zircons (250-220 Ma) were presumably derived from mag matic and volcanic rocks that are related to the Sibe rian plume and known in Taimyr (Vernikovsky et al, 2003;Walderhaug et al, 2005) and Siberian Craton (Reichow et al, 2009), as well as in boreholes in northern West Siberia (Saraev et al, 2009;Nikishin et al, 2011).…”

Morphotectonic and Petrological Characteristics of Permo-Triassic Traps of Siberia

“…In [20] considered all post-Paleozoic igneous events of the Russian sector of Asia were considered as rifting processes, although there are no signs of classical rifts of the PTTS igneous systems in the described structural forms of the magma development in the sedimentary cover and subaerial mantle flows for SC and Taimyr [21][22][23][24][25][26][27][28][29]. The described manifestations of subaerial volcanism beneath the Mesozoic cover on the WSP territory [30][31][32][33] also do not contain geological and structural information about morphological structures common for classical rifting, therefore morphological structures characteristics of the PTTS manifestation of terrestrial magmatism should be studied by instrumental techniques.…”

On the importance of rock thermal conductivity and heat flow density in basin and petroleum system modelling

“…Sedimentation cessation (hiatus) occurred in the Middle Jurassic when sea level was relatively low (Figure ). In geological history, there are several peak sedimentation rates: during the rift phase after a basaltic effusion (Saraev, Baturina, Ponomarchuk, & Travin, ), Early Jurassic, end of middle Jurassic and Neocomian marked as the period with rapid sedimentation (Ershov, ) at least 3× times faster than adjacent periods of relatively constant burial rate. Subsidence changed to uplift with an erosion thickness of 300 m and level at 0 m in the Neogene (Galushkin et al, ).…”