西昆仑库孜——带长城纪火山岩地球化学特征及地质意义

Geochemical Characteristics and Geological Significance of Statherian Volcanic Rocks in Kuzi Area in Western Kunlun

摘要:

西昆仑库孜一带长城纪赛图拉岩群为一套火山熔岩火山碎屑岩沉积岩组合，火山岩主体为中酸性岩。通过对该地区长城纪火山岩分布特征、岩石学特征及地球化学特征进行分析研究，划分了2个火山喷发旋回。2个喷发旋回岩性无明显区别，均为一套中酸性火山熔岩、火山碎屑岩、沉积岩建造。第一喷发旋回自下而上见7个喷发韵律，爆发指数为41.70%，喷溢指数24.51%，该旋回岩相总体表现为爆发—喷溢—沉积—爆发—沉积—爆发的特点；第二喷发旋回自下而上见4个喷发韵律，爆发指数为46.67%，喷溢指数为18.15%，该旋回岩相总体表现为爆发—沉积—爆发—沉积—爆发的特点，揭示了西昆仑库孜一带古塔里木陆块裂解古洋盆的演化特征，对研究该地区古陆块裂解具有一定的借鉴意义。

Abstract:

Statherian Saitula group in Kuzi area in western Kunlun is a set of volcanic lavapyroclastic rock sedimentary rock assemblage, and the volcanic rocks are mainly intermediateacid rocks. Based on the analysis of the distribution, petrological and geochemical characteristics of Statherian volcanic rocks in this area, two volcanic eruption cycles are divided. There is no obvious difference in lithology between the two eruption cycles, all of which are a set of mediumacid volcanic lava, pyroclastic rocks and sedimentary rocks. Seven eruption rhythms from bottom to top can be found in the first eruption cycle. The burst index is 41.70 %, and the eruption index is 24.51 %. The cyclic lithofacies shows the characteristics of burst eruption deposition eruption deposition eruption. There are four eruption rhythms from bottom to top in the second eruption cycle. The eruption index is 46.67 %, and the eruption index is 18.15 %. The lithofacies of the cycle shows the characteristics of eruption deposition eruption deposition eruption. It is revealed that the evolution characteristics of the ancient ocean basin has been cracked by the Guttari continental block in Kuzi area in western Kunlun mountains. It has certain guiding significance for the study of the ancient ocean basin cracked by the continental block in this area.