Timan-Pechora Composite Tectono-Sedimentary Element

AbstractTiman-Pechora Composite Tectono-Sedimentary Element represents a significant part of the Timan-Pechora petroleum province, which is the second largest in the Circum-Arctic. It contains as much as up to 10 km of Paleozoic and Mesozoic strata hosting world-class hydrocarbon source rock, the Domanik Formation, and a variety of hydrocarbon plays prolific for both, oil and natural gas. Complex tectonic structure of the composite tectono-sedimentary element formed as result of several tectonic phases: two extensional events, post-rift thermal sag in a passive margin setting, and a series of late Paleozoic and early Mesozoic compressional events. The latter modified the extensional fabric and led to the formation of a number of inverted swells and smaller anticlinal structures providing the major trapping capacities. The deposition of source and reservoir facies occurred during the extensional tectonic phases, while the main reservoir-prone sedimentary units were deposited during late Paleozoic and early Mesozoic orogenic phases.

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Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic—Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

Minerals ◽

10.3390/min11060573 ◽

2021 ◽

Vol 11 (6) ◽

pp. 573

Author(s):

Shahid Iqbal ◽

Michael Wagreich ◽

Mehwish Bibi ◽

Irfan U. Jan ◽

Susanne Gier

Keyword(s):

Lower Jurassic ◽

Sediment Supply ◽

Heavy Mineral ◽

Passive Margin ◽

Indian Plate ◽

Late Triassic ◽

Indian Shield ◽

Margin Setting ◽

Salt Range ◽

Mineral Data

The Salt Range, in Pakistan, preserves an insightful sedimentary record of passive margin dynamics along the NW margin of the Indian Plate during the Mesozoic. This study develops provenance analyses of the Upper Triassic (Kingriali Formation) to Lower Jurassic (Datta Formation) siliciclastics from the Salt and Trans Indus ranges based on outcrop analysis, petrography, bulk sediment elemental geochemistry, and heavy-mineral data. The sandstones are texturally and compositionally mature quartz arenites and the conglomerates are quartz rich oligomictic conglomerates. Geochemical proxies support sediment derivation from acidic sources and deposition under a passive margin setting. The transparent heavy mineral suite consists of zircon, tourmaline, and rutile (ZTR) with minor staurolite in the Triassic strata that diminishes in the Jurassic strata. Together, these data indicate that the sediments were supplied by erosion of the older siliciclastics of the eastern Salt Range and adjoining areas of the Indian Plate. The proportion of recycled component exceeds the previous literature estimates for direct sediment derivation from the Indian Shield. A possible increase in detritus supply from the Salt Range itself indicates notably different conditions of sediment generation, during the Triassic–Jurassic transition. The present results suggest that, during the Triassic–Jurassic transition in the Salt Range, direct sediment supply from the Indian Shield was probably reduced and the Triassic and older siliciclastics were exhumed on an elevated passive margin and reworked by a locally established fluvio-deltaic system. The sediment transport had a north-northwestward trend parallel to the northwestern Tethyan margin of the Indian Plate and normal to its opening axis. During the Late Triassic, hot and arid hot-house palaeoclimate prevailed in the area that gave way to a hot and humid greenhouse palaeoclimate across the Triassic–Jurassic Boundary. Sedimentological similarity between the Salt Range succession and the Neo-Tethyan succession exposed to the east on the northern Indian passive Neo-Tethyan margin suggests a possible westward extension of this margin.

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