No abstract

No abstract

This paper is based on the results of the work done during a long period of time in the framework of the International Project "Atlas of Lithopaleographic, Structural and Geoecological Maps of Central Eurasia". Having generalized the original and published data available for the geologic structure and paleomagnetism of the Altai-Sayan and Ural regions, the Siberian Craton, the East-European Platform, Mongolia, Kazakhstan, and Tien Shan, palinspastic maps have been compiled for the Vendian, Early Cambrian, and Early and Late Ordovician (600, 525, 500, and 450 Ma). The maps depict the composition of the rocks and the environments of their origin. The structure, evolution, and geological history of the Paleoasian Ocean is described as a system of marginal basins and island arcs belonging to the continental margin of the East Paleogondwana (a fragment of the Rodinia Supercontinent), including the early stages of the transformation of the Paleoasian Ocean into a fold-and-nappe structure. The maps are accompanied by numerous cross sections, palinspastic profiles, and maps of some areas, showing the details of individual structural features. This paper is based on the results of the long investigations done in the framework of the international project "At

In this paper, we discuss three petroleum‐bearing basins of Palaeozoic age in Central Eurasia—the Precaspian, Tarim and Chu‐Sarysu Basins. We make use of recently‐published palaeogeographic maps of the Central Eurasian region, six of which are presented here (Late Ordovician, Early‐Middle Devonian, Late Devonian, Early Carboniferous, Early Permian and Late Permian). The maps illustrate the development through the Palaeozoic of the Palaeoasian and Palaeotethys Oceans; of the East European, Siberian and Tarim cratons; and of the Kazakhstan and other microcontinental blocks. The Kazakhstan block formed during the Late Ordovician and is a collage of Precambrian and Early Palaeozoic microcontinents and island arcs. It is surrounded by collisional foldbelts (Ob‐Zaisan, Ural‐Tianshan and Junggar‐Balkhash) which formed in the Late Carboniferous — Permian. We believe that the formation of a stable Kazakhstan block is not consistent with the existence of the previously‐identified “Kipchak arc” within the Palaeoasian ocean, or (as has previously been proposed) with activity on this arc up to the end of the Palaeozoic. The oil and gas potential of the Precaspian, Tarim and Chu‐Sarysu Basins depends to a large extent on their tectonic stability during the Palaeozoic and subsequent time. The Precaspian Basin has been stable since the Cadomian orogeny (Early Cambrian) and is known to have major hydrocarbon potential. The Tarim Basin (NW China) has somewhat lower potential because the margins of the Tarim continental block have been affected by a series of collisional events; that margin with the Palaeotethys Ocean, for example, was active during the Late Palaeozoic. The Chu‐Sarysu Basin on the Kazakhstan block is the least stable of the three and contains only minor gas accumulations.

No abstract