东准噶尔卡拉麦里晚古生代岩石圈“阶段式”拆沉机制--来自A型花岗岩带同位素年代学及地球化学的证据  

"Stage type"Delamination Mechanism of Late Paleozoic Lithosphere in Kalamaili,East Junggar--Evidence from Isotopic Chronology and Geochemistry of A Type Granite Belt

作　　者：张治中 张博文 冯京[3] 陈川 高丹[1,2] Zhang Zhizhong;Zhang Bowen;Feng Jing;Chen Chuan;Gao Dan(College of Geology and Mining Engineering Xinjiang University,Urumqi,Xinjiang,830049,China;Laboratory of Continental Dynamics and Metallogenic Prognosis of Central Asian Orogenic Belt,Urumqi,Xinjiang,830049,China;Xinjiang Uygur Bureau of Geology and Mineral Resources,Urumqi,Xinjiang,830000,China)

机构地区：[1]新疆大学地质与矿业工程学院,新疆乌鲁木齐830049 [2]新疆大学中亚造山带大陆动力学与成矿预测实验室,新疆乌鲁木齐830049 [3]新疆维吾尔自治区地质矿产勘查开发局,新疆乌鲁木齐830000

出　　处：《新疆地质》2022年第1期12-19,共8页Xinjiang Geology

基　　金：国家重点研发计划项目(2018YFC0604003)。

摘　　要：东准噶尔是中亚造山带在新疆北部区域的重要组成单元,是晚古生代岩浆剧烈活动的区域,以发育卡拉麦里巨量富碱花岗岩带为主要特征,也是中亚造山带发育年轻地壳的典型地区。通过分析该地区巨量深成岩浆岩来重塑岩石圈拆沉作用及新生地壳生长机制成为新的研究热点。近年来,众多学者对卡拉麦里岩带内的6个主要岩体的岩相学、岩石地球化学、年代学及Nd-Hf同位素进行大量研究,认为该地区深成岩浆活动主要集中于330~280 Ma之间,形成于后碰撞伸展环境。由新生下地壳部分熔融演化,派生的大规模A2型花岗岩是研究该地区岩石圈拆沉作用最重要的岩石探针。结合前人研究成果综合得出,该岩带6个岩体的花岗岩自西北向东南,存在岩浆结晶年龄逐渐年轻,就位深度变大,岩浆分异程度降低,且岩浆条件由还原-中等还原性向氧化性过渡的空间差异性,这种差异暗示该地区晚古生代岩石圈减薄可能是由西北向东南诱发的“阶段式”拆沉机制造引起。The Eastern Junggar in Northern Xinjiang province is an important component unit of the Central Asian Oro-genic Belt,and is a significant area of Late Paleozoic magmatism.It is characterized by the development of Karamari massive alkali rich granite belt,and also a typical area where the Central Asian Orogenic Belt develops juvenile crust.At present,it has become a new research hotspot to reconstruct the lithosphere delamination and the growth mechanism of the juvenile crust by analyzing the huge amount of plutonic magmatite in this area.In recent years,many scholars have done a lot of research on petrography,petrochemistry,geochronology and Nd-Hf isotopes of six main plutons in the Kar-amari belt.It is concluded that the plutonic magmatism in the area is mainly concentrated in 330-280 Ma.The large scale A2 type granite formed in the post collisional extensional environment and evolved from the partial melting of the newborn lower crust is the most important rock probe to study the lithospheric delamination in this area.Combined with the results of previous research,it is concluded that there are six granite plutons in the belt from northwest to southeast,with magma crystallization age gradually younger,emplacement depth deeper,the degree of magma differentiation de-creasing,and the spatial difference of the transition of magma conditions from reducibility to medium-reducibility to oxi-dizability.This difference suggests that the lithospheric thinning in the late Paleozoic period may be caused by a“staged”delamination triggered from west to east.

关 键 词：东准噶尔 卡拉麦里花岗岩带 A型花岗岩 “阶段式”拆沉作用 

分 类 号：P534.4[天文地球—古生物学与地层学] P588.115[天文地球—地质学]