Rassokhin arch is a large anticlinal structure in the central part of the Yenisey-Khatanga regional downwarp. It measures 550 km by 30-45 km. It has steep flanks and flat crest. Along this crest from west to east are the Ozernaya, Makhov, Verkhne-Kubin, Dzhangod, Tundrov, Volochan, Novaya, and Kur'in local highs. Gas fields have been discovered in Ozernaya and Dzhangod areas in Crertaceous and Jurassic sediments. An oil-saturated section has also been found in the Verkhne-Kubin area. Results have been negative for the Novaya and Tundrov highs.
Deep drilling on this arch has not been extensive. Its width narrows as it plunges to the west to within 50-60 km of the Yenisey River. In its western part it is disposed en echelon to the Malokhet arch. The western and eastern noses of this arch have not been studied adequately.
Balakhnin arch extends from southwest to northeast in the eastern part of Yenisey-Khatanga regional downwarp and is separated from the North Siberian monocline by the relatively deep and narrow Zhdanikhin downwarp. The axis of the Balakhnin arch is on line with that of the Kiryano-Tass arch on its east.
Balakhnin arch measures 250 by 50 km. Hardly any Cretaceous is present at its crest. Three local highs have been mapped: Balakhnin, Kubalakh, and Vladimirov. Deep wells have been drill at their crests. A gas field has been discovered in the Balakhnin area. The Jurassic rocks in this area were drilled to a depth of 3800 m. This unusual thickness of the Jurassic here has led to the concept that the Balakhnin arch formed on the site of a Jurassic (and Triassic) downwarp and that it is an inversion structure that developed in Late Jurassic and Neocomian time.
The Malokhet, Rassokhin, and Balakhnin arches are a system of large linear anticlines along the north side of a deep fault that reaches the upper mantle. Displacement on this fault is 2-4 km along its entire length. The arches are overthrust along it from north to south. Greatest displacements were in the Late Jurassic and Early Cretaceous, which was also a time of fundamental change in the regime of downwarping in West Siberia.
These arched have diverse nature: Malokhet inherited arch, Rassokhin newly formed arch, and Balakhnin inversion arch. They are interpreted as non-platformal fault-associated features along the margin of a lithospheric plate.
In Jurassic time before development of the system of arches a large marine basin was disposed along what is now the Yenisey- Khatanga regional downwarp, along which the sea penetrated into West Siberia from the Laptev Sea area. After formation of the arches the connection between the Cretaceous marine basins of West Siberia and the Laptev Sea was broken. Neocomian clinoforms developed largely in the western part of Yenisey- Khatange regional low and are absent to the east of Rassokhin arch.
Oil-gas prospects of this region are very favorable. In the crest areas and north flanks of Rassokhin and Balakhnin arches the greatest interest is in the Lower Jurassic-Bajocian oil-gas complex in zones of intensive stable downwarping and accompanying zones of pinchout.
Taken from Baldin, K. N. Kunin, and N. Ya. Kunin, 1997;
digested in Petroleum Geology, vol. 31, no. 4, 1997, one map
and two cross sections.
Copyright 2002 James Clarke. You are encouraged to print out
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