祁连山-柴北缘地区岩浆活动的时空分布、成因演变及构造岩浆演化  

Spatial-Temporal Distribution,Petrogenetic Evolution and Tectono-Magmatic Evolution in Qilian Mountains and Northern Margin of Qaidam

作　　者：李平[1] 高晓峰[1] 吕鹏瑞[1] 朱小辉 陈隽璐[1,3] LI Ping;GAO Xiaofeng;LÜPengrui;ZHU Xiaohui;CHEN Junlu(Xi’an Center of China Geological Survey,Center for Orogenic Belt Geology,Xi’an 710119,Shaanxi,China;Yan’an University,Yan’an 716000,Shannxi,China;Strata Type Section for the Bottom of Wenlock-Shaanxi Ziyang Field Scientific Observation,Xi’an 710054,Shaanxi,China)

机构地区：[1]中国地质调查局西安地质调查中心/中国地质调查局造山带地质研究中心,陕西西安710119 [2]延安大学,陕西延安716000 [3]陕西紫阳中志留统底界层型剖面野外科学观测研究站,陕西西安710054

出　　处：《西北地质》2023年第4期283-317,共35页Northwestern Geology

基　　金：中国地质调查局项目(DD20230005,DD20230032,12120114020501,DD20221691,DD30230028);陕西省自然科学基础研究计划(2023-JC-YB-268,2023-JC-ZD-15,2022JM-149);国家自然科学基金(41502061)联合资助。

摘　　要：祁连山及邻区广泛出露有形成于不同时代、具有复杂成因类型的侵入岩类,它们记录了祁连山、柴北缘和宗务隆构造带多阶段、多期次的构造岩浆事件。根据侵入岩的空间展布情况、年代学时空格架和岩石成因类型,祁连山-柴北缘地区的侵入岩浆活动主要可分为3个阶段:前寒武纪(2.47 Ga~561 Ma)、早古生代—泥盆纪(517~360 Ma)、中晚二叠世—三叠纪(271~210Ma)。(1)前寒武纪花岗岩(2470~561 Ma)的形成记录了区内古老大陆的聚合、离散过程及北祁连洋的开启。(2)自前寒武纪末期洋盆打开以来,祁连山和柴北缘地区在517~359 Ma形成有大量的侵入岩类,祁连山、柴北缘和宗务隆地区自中泥盆世以来开始明显的显示出相对独立的构造-岩浆演化过程。其中,自517 Ma以后,祁连山地区形成有俯冲成因地球化学特征的花岗岩、埃达克质岩石和碱性花岗类,与区内同期火山岩一同构成弧盆系的火山-侵入岩组合;中南祁连在奥陶纪(452~444 Ma)和早志留世初(431 Ma)广泛形成的强过铝质S型碰撞成因花岗岩与晚奥陶世出现的磨拉石沉积建造,表明了祁连山碰撞造山事件发生于晚奥陶世—早泥盆世(452~431Ma)阶段;柴北缘地区可能于463 Ma左右已经开始进入碰撞-后碰撞造山阶段,略早于祁连山地区。440~425 Ma阶段,大量高Mg中性侵入岩和具有正εNd(t)、εHf(t)值同位素特征的埃达克质岩类,与430~420 Ma阶段的A型花岗岩,共同代表了中-南祁连后碰撞造山伸展作用。至泥盆纪,祁连山和柴北缘地区岩浆作用显示相对独立的构造演化进程。祁连地区该阶段侵入岩浆活动开始急剧减弱,北祁连少量形成于409~402 Ma阶段的A型花岗岩、中南祁连386 Ma的辉绿岩岩墙和老君山组山间磨拉石的出现,为祁连山在中泥盆世开始由后碰撞造山转为陆内伸展作用的地质记录;柴北缘地区在402~367 Ma折返及后续造山过程中发育有高Sr、Types of intrusions with different formation ages are widely exposed in Qilian Mountains and its adjacent areas,which record multi-stage tectono-magmatic events in Qilian Mountains,Northern Margin of Qaidam and Zongwulong tectonic belt.According to the spatial distribution,chronological framework and petrogenetic types,the intrusive magmatism in Qilian-Northern Margin of Qaidam region can be divided into three stages:Precambrian(2470~561 Ma),Early Paleozoic to Devonian(517~360 Ma),and Middle-Late Permian to Triassic(271~210 Ma).①The Precambrian granites(2470 Ma~561 Ma)recorded the process of convergence and dispersion of ancient continents and the opening of the North Qilian Ocean.②Since the opening of the Sinian ocean basin,a large number of intrusions have been formed between 517 and 359 Ma in Qilian Mountains and the Northern Margin of Qaidam.Since the Middle Devonian,the Qilian Mountains,the Northern Margin of Qaidam and the Zongwulong region have began to shown relatively independent tectonic-magmatic evolution process.Since 517 Ma,granitoids with geochemical characteristics of slab subduction,adakitic rocks and alkaline granites have been formed in Qilian Mountains,together with the volcanic rocks formed in the same period can constitute a volcanic-intrusive rock association of the arc-basin system.The strongly peraluminous S-type collision-related granites widely formed in the Ordovician(452~444 Ma)and Early Silurian(431 Ma)in Central and Southern Qilian,and the molasse sedimentary formation occurred in the Late Ordovician,indicate that the Qilian collision orogenic event occurred during the Late Ordovician and Early Devonian(452~431 Ma).In addition,the Northern Margin of Qaidam may have entered the collision-post-collision orogenic stage at ca.463 Ma,slightly earlier than that of Qilian Mountains.In 440~425 Ma stage,a large number of high Mg neutral intrusive rocks,adakitic rocks with positiveεNd(t)andεHf(t)values and the A-type granites formed during 430 Ma and 420 Ma,represent the post-collision o

关 键 词：祁连山-柴北缘地区 宗务隆构造带 花岗岩浆作用 构造演化 

分 类 号：P588.1[天文地球—岩石学]