摘要
塔里木克拉通保存有古元古代晚期与哥伦比亚超大陆演化相关的岩浆和构造记录。本文综述了塔里木克拉通周缘的古元古代晚期A型花岗岩,识别出两期(1.95Ga和1.85~1.73Ga)具不同地球化学特征的A型花岗岩。两期花岗岩均来源于具英云闪长岩和花岗闪长岩成分特征的地壳的部分熔融。~1.95Ga花岗岩具有相对较高的SiO2和Sr含量、Y/Nb和Ce/Nb比值、较低的εHf(t)值(-13~-5.2),为A2型花岗岩,形成于活动大陆边缘或弧后伸展等构造环境;而1.85~1.73Ga花岗岩具有相对较低的SiO_(2)和Sr含量、Y/Nb和Ce/Nb比值、和较高的ε_(Hf)(t)(-5.9~+8.7)和ε_(Nd)(t)(-6.2~-2.5)值,为A2向A1过渡类型,形成于碰撞后伸展或者陆内伸展裂解背景。笔者综述还发现塔里木克拉通内部存在两期不同的元古代晚期岩浆和变质年龄也可以明显的分为两期,岩浆岩峰值分别为1.93Ga和1.85Ga,变质年龄峰值为1.96Ga和1.84Ga,说明塔里木克拉通内部存在两期不同的晚古元古代构造-岩浆事件。这两期构造-岩浆事件对应于俯冲型造山和碰撞造山后伸展环境,可能分别记录了哥伦比亚超大陆聚合和裂解过程,也就是说哥伦比亚超大陆可能在1.85Ga左右已经开始部分裂解。
Lots of late-Paleoproterozoic magmatic and tectonic records,which are commonly interpreted as products of the Columbia assembly and break-up,were preserved in the Tarim Craton.In this study,we summarized the late-Paleoproterozoic A-type granitoids at the periphery of the Tarim Craton,and identified two A-type granitoid flare-ups at 1.95 Ga and 1.85~1.73 Ga.All these A-type granitoids are derived from partial melting of the crustal materials with tonalitic to granodioritic compositions.The ca.1.95 Ga granites show high Si O2 and Sr contents,high Y/Nb and Ce/Nb ratios,low ε_(Hf)(t)values(-13~-5.2),and could be classified as A2 subtype granitoid.They were formed in continental arc or back-arc settings.The 1.85~1.73 Ga granites show relatively low SiO_(2) and Sr contents,low Y/Nb and Ce/Nb ratios,high ε_(Hf)(t)(-5.9~+8.7)and ε_(Nd)(t)(-6.2~-2.5)values,and could be classified as A2 to A1 transitional subtype.They were formed in post-collisional or intracontinental extension settings.Besides,magmatism and metamorphism ages in the Tarim Craton also show two peaks at 1.93 Ga and 1.85 Ga,1.95 Ga and 1.84 Ga,respectively.These age data suggest that the Tarim Craton may have experienced two significant tectono-magmatic events at about 1.93 Ga and 1.85 Ga.These two events may record the subduction related orogeny and collisional orogeny,and are related to the Columbia assembly and break-up,respectively.We believed that the Columbia supercontinent may have broken up at 1.85 Ga.
作者
张永旺
刘汇川
于志琪
王凯
ZHANG YongWang;LIU HuiChuan;YU ZhiQi;WANG Kai(State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China)
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2021年第4期1122-1138,共17页
Acta Petrologica Sinica
基金
中国石油大学(北京)科研基金(2462018YJRC030、2462020YXZZ020)
国家自然科学基金项目(41572113)联合资助。
