STRUCTURE OF THE MONGOL-OKHOTSK OROGENIC BELT AND THE PROBLEM OF RECOGNITION OF THE AMUR MICROCONTINENT
I.V. Gordienko1, D.V. Metelkin2,3, L.I. Vetluzhskikh1
1Institute of Geology, Siberian Branch of the Russian Academy of Sciences, ul. Sakh’yanovoi 6a, Ulan-Ude, 670047, Russia
2Novosibirsk State University, ul. Pirogova 2, Novosibirsk, 630090, Russia
3A.A. Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090, Russia
Keywords: Neoproterozoic, Vendian, Early Cambrian, paleomagnetism, sedimentary basins, paleotectonic reconstructions, Mongol-Okhotsk belt, Amur microcontinent, Argun terrane, Siberian paleocontinent
Abstract
A new concept of the geologic structure and geodynamic evolution of the Mongol-Okhotsk Orogenic Belt is proposed. The problems of recognition of the Amur composite microcontinent (Amuria superterrane) and substantiation of its existence are considered. We present recent data on the geologic structure, composition, age, and paleomagnetism of the Neoproterozoic-Paleozoic complexes, one of the main elements of Amuria: Argun terrane and adjacent Transbaikalian and Mongolian structures. In particular, we refine the age of Precambrian and Paleozoic stratified and igneous units. The absence of an Archean-Paleoproterozoic crystalline basement is shown. Using our paleomagnetic and paleontological data, we substantiate the equatorial position of the Argun terrane in the immediate vicinity of Siberia in the period 560-525 Ma. The results of the research and analysis of available geological data on the Argun terrane and adjacent Transbaikalian and Southeast Asian structures clearly show the fallacy of the concept of the Amur composite microcontinent as a single tectonic element whose collision resulted in the folded structures of the Mongol-Okhotsk belt. This conclusion is of crucial importance for the reconstruction of the Neoproterozoic, Paleozoic, and Mesozoic geodynamic evolution of the eastern part of the Central Asian Orogenic Belt.
DOI: 10.15372/RGG2019018
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