The Characteristics Of The Permian Volcanic Rocks And Temporal-spatial Distribution In The Tazhong Region, Xinjiang

The early Permian volcanic rocks are widely distributed in the Tazhong region.The research of lithologic characteristics and spacial distribution of volcanic rocks is a key to reveal the tectonic setting and late Paleozoic regional tectonic evolution.In the thesis,taking the volcanic rocks of the typical established formation section in the Kaipaizileike formation and Kupukuzimanzu as an object of study. Based on the systematic research of petrology, geochemistry and component charge of regional volcanic rocks,the formation age of the volcanic rocks are determined and the magma sources and its properties are studied.The research also elucidates the tectonic setting of volcanic rocks. The main points of understanding are as follow.(1) Tazhong developed two periods of the volcanic rocks in a total of five cycles in the permin. According to paleontological geochronology and isotope age of the volcanic rocks of these two phases are formed during the Early Permian, the Kupukuziman formation is the Qixia period of the early Permian, and the Kaipaizileike formation is the late of early Permian (Maokou period).(2) Tazhong Permian volcanic rocks mostly are basic, the main characteristics of the distribution as follows: east thick west thin; north-south thick, the middle thin, volcanic rock distribution is mainly affected by fault.(3) Tazhong Permian volcanic rocks in the combination of alkali basalt - basanite- trachybasalt– basalt are an alkaline series in accordance with tholeiitic series of the trend of.evolution.(4) Through comparative analysis of trace elements and Sr, Nd, Pb isotope tracer, indicating Tazhong Permian volcanic rocks from the continental lithosphere magma mantle, mainly formed by fractional crystallization, the rock-rich Ba, Th, K, Rb, etc. large-ion lithophile elements (LILE), loss of Sc, Cr, Y high field strength elements (HFS), with a continental rift geochemical properties of volcanic rocks.