Geochemical characteristics and geological significance of Qingtashan rock mass in Qiemo County of Xinjiang
Qingtashan rock mass is located in the western section of East Kunlun,and the formation age,environ-ment and rock type of the rock mass are still controversial,with low research degree of the physicochemical condi-tions during the process of rock formation and its source characteristics.On the basis of systematic lithology and petrographic research,the authors in this paper conducted composition analysis on the main rock-forming miner-als such as biotites,plagioclases and hornblendes.The physicochemical conditions during the process of rock for-mation were identified and petrogenesis of the rock was further constrained.This study shows that the lithology of Qingtashan rock mass is tonalites,and the lithology of the dike is quartz-diorites.The Plagioclase feldspar in the rock mass is andesine and labradorite,the biotite is magnesiobiotite,and the hornblende is magnesiohornblende.An anti-zoning band was developed in the plagioclase,which was caused by magma mixing.The crystallization temperature is 684～693 ℃ and the crystallization pressure is(1.86～2.01)× 108 Pa,with average value of 1.92 x 108 Pa.The corresponding crystallization depth is 6.90～7.46 km,with an average of 7.12 km,belong-ing to the medium-deep formation phase.The oxygen fugitivity during rock mass formation is low,which is be-tween-17.34 and-17.04.The mineral chemical characteristics show that the material source of the biotite in Qingtashan rock mass is calc-alkaline orogenic suite,and its formation is related to the crust-mantle mixed source magmatic.This study could provide references for the evolution of Late Triassic-Early Jurassic magma in this region.
万方数据
维普
