THE TIEN SHAN EARLY PALEOZOIC TECTONICS AND GEODYNAMICS

Abstract

Reported in this paper are the results of the analysis and generalization of the geological, radiometric, paleomagnetic and biogeographical data obtained in the Western, Central, and Eastern Tien Shan during the study of the Late Neoproterozoic and Early Paleozoic rocks. Earlier the Tien Shan rocks belonged to the Alay-Tarim Early Paleozoic continent, as well as to a few microcontinents and oceanic basins. From the Vendian to the Late Carboniferous the Turkestan oceanic basin separated the Alay-Tarim continent from the assemblage of microcontinents and island arcs the rocks of which compose the North Turkestan domain of the present-day Tien Shan. During the Early Paleozoic the rocks of this domain composed the Borohoro, Issyk Kul, and Syr Darya microcontinents. These microcontinents were separated by the Terskey and Ili oceanic basins, where oceanic island arcs originated and disappeared. These oceanic basins were closed during the collision of the microcontinents in the Early Ordovician (Terskey Basin) and in the Silurian (Ili Basin). The structural features of the region also described and discussed in this paper, as well as the tectonic processes that operated in the Early Paleozoic, including their evolution and geodynamics.