THE AGE AND TECTONIC SETTING OF VOLCANIC AND CHERTY SEQUENCES IN THE OPHIOLITE COMPLEX OF THE ATBASHE RIDGE (SOUTHERN TIEN SHAN)

Abstract

Dating the sedimentary and volcanic rocks in ophiolite complexes is of fundamental importance for reconstructions of oceanic paleobasins. The ophiolite belt of the southern Tien Shan, which extends from northwestern Uzbekistan to western regions of China, traces the suture of the Turkestan paleocean closed at the end of the Carboniferous. In the western part of the belt, the age of volcanic–cherty sequences of the ophiolite association corresponds to the Early Ordovician–Early Carboniferous interval. Data on the age of similar rocks in eastern regions are rather scanty. Therefore, several issues related to evolution of the Turkestan paleocean in the region between the Kazakhstan and Tarim continental blocks remain open. To fill this gap, we have carried out micropaleontological study of cherty–volcanic sequences developed within the ophiolite belt in the Atbashe and Dzhangdzhir ridges.