International Geologiical Congress - Oslo 2008

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ASI-02 Geology and mineral resources of Northern and Central Eurasia

 

New tectonic map of central Asia at 1:2.5 M scale: Trends of origination and reworking of consolidated crust

 

Oleg Petrov, A.P. Karpinsky Russian Geological Research Institute (VSEGEI) (Russian Federation)
Yuri Leonov, Geological Institute (GIN) RAS (Russian Federation)
Igor Pospelov, Geological Institute (GIN) RAS (Russian Federation)
Sergey Shokalsky, A.P. Karpinsky Russian Geological Research Institute (VSEGEI) (Russian Federation)
O. “Ómurtogoo, The Institute of Geology and Natural Resources MAS (Mongolia)
V.Ya.  oshkin, K.I. Satpaev Institute of Geological Sciences NAS (Kazakhstan)
Bingwei Chen, Geological Institute of the Chinese Academy of Geological Sciences (China)
Jaeha Hwang, Korean Institute of Geology and Mineral Recourses (KIGAM) (Republic of Korea)
 

 

The tectonic map of Central Asia and adjacent areas at a 1:2,500,000 scale was compiled in 2003-2007 by the Geological Surveys of Russia, China, Mongolia, Kazakhstan, and the Republic of Korea, also by the CGMW subcommissions for Northern Eurasia and for Tectonic Maps. The map clearly shows traces of interaction of two main types of tectonic process responsible for origination and reworking of the consolidated crust of Eurasia:
(1) deep mantle diapirism (intracontinental rifting);
(2) plate tectonic lithospheric geodynamics (spreading, accretion and collision). As a result of a combination of these processes, the granitic-metamorphic crust of Central and Eastern Asia formed.

The history of crust formation can be divided into six consolidation phases corresponding to the Paleoproterozoic through to the Late Mesozoic. Its reconstruction is based on the preserved geological complexes of paleooceanic, active and passive margin continental geodynamic settings. The tectonic map shows lateral and, partly, chronological changes of the accretionary Pacific style of structure evolution into the Indo-Atlantic style, typified by rifting and collision processes. As a result of multi-stage structural-thermal reworking, many seismofocal paleozones and paleosutures were repeatedly reworked and transformed into transcontinental strike-slip faults and shear zones accompanied by lateral movements of lithospheric masses, stress-metamorphism and intrusive magmatism.
Tectonic processes at a deep "mantle" level of continental rifting took place on the vast territories of Central and Eastern Asia and resulted in the formation of large magmatic provinces and areas of intraplate flood-basalt, alkali-basic, carbonatite, kimberlite, explosive breccia and other magmatic types. Each major phase of destruction and transformation of consolidated crust was accompanied by the formation of rift-related depression systems or extensive sedimentary basins. These phases embraced the following time intervals: beginning of the Mesoproterozoic, end of the Mesoproterozoic to the beginning of the Neoproterozoic, Cambrian to Ordovician, Devonian, end of the Permian to Early Triassic, Jurassic, Early Cretaceous and Cenozoic. The resulting central type magmatic structures and linear systems of rift-related grabens are clearly expressed in the modern topography of Central and Eastern Asia.

 

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