新疆富蕴县希勒库都克钼铜矿区岩浆活动特征及其对区域晚-后碰撞构造演化的制约  

Characteristics of magmatic activity in the Xilekuduke Mo-Cu ore district,Fuyun County,Xinjiang,and its constrains on regional tectonic evolution in late-post collisional stages

作　　者：游军[1,2] 洪涛[1,2] 吴楚[3,4] 丁汝福[5] 徐兴旺[1] 

机构地区：[1]中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学,北京100049 [3]地质过程与矿产资源国家重点实验室,中国地质大学,北京100083 [4]中国地质大学地球科学与资源学院,北京100083 [5]有色金属矿产地质调查中心,北京100012

出　　处：《岩石学报》2016年第5期1262-1282,共21页Acta Petrologica Sinica

基　　金：国家自然科学基金项目(41390442);国家科技支撑计划项目(2011BAB06B03-3;2011BAB06B03-5);中国科学院知识创新工程主要方向项目(KZCX-EW-LY03)联合资助

摘　　要：新疆北部地区不同地体间的碰撞时间与碰撞过程的成矿作用是中亚造山带与成矿研究的热点问题。对于新疆北部地区是否存在晚碰撞岩浆活动、碰撞与后碰撞的转化时间及转化过程中的岩浆活动与成矿作用特征尚不清楚。本文报道了新疆东准噶尔希勒库都克钼铜矿区岩浆演化的研究成果。矿区存在3期岩浆活动形成4种岩石类型,依次为340Ma的闪长玢岩、328Ma的二长花岗岩与325Ma的花岗斑岩、315Ma石英斑岩。4种岩石均具高钾钙碱性特征。闪长玢岩形成于碰撞晚期环境,具有典型的岛弧地球化学特征,属准铝质岩石,无铕异常,亏损Nb、Ta、Ti,无P亏损;二长花岗岩、花岗斑岩形成于后碰撞早期环境,其中二长花岗岩具有弧与后碰撞过渡的地球化学特征,属弱过铝质岩石,弱正铕异常,亏损Nb、Ta、Ti,P中等程度亏损;花岗斑岩具有不典型后碰撞的地球化学特征,属弱过铝质岩石,负铕异常,明显亏损Nb、Ta、Ti,较强P亏损;石英斑岩形成于后碰撞伸展阶段并具有后碰撞的地球化学特征,属弱过铝质岩石、负铕异常,亏损Nb、Ta、Ti,强P亏损。矿区侵入岩具有较低的(87Sr/86Sr)i初始值(0.702976~0.704306)和相对较高的εNd(t)值(+5.8^+6.8),模式年龄(tDM)为524~588Ma,其可能主要源于早古生代洋壳的部分熔融。建立了萨吾尔岛弧晚古生代的构造演化模式及成岩、成矿过程,认为萨吾尔岛弧在晚古生代经历了俯冲期(400~370Ma)、主碰撞期(360~340Ma)、碰撞晚期(340~330Ma)、后碰撞早期(330~320Ma)以及后碰撞伸展阶段(320~280Ma)五个阶段。The time and metallogenesis of collision between different terrains is one of the hottest topics for tectonic evolution and mineralization of the Central-Asia Orogenic Belt. It ＇s unclear that whether there is late-collisional magmatic activity in northern Xinjiang area. The tectonic transformation time from collision to post-collision,characteristics of magmatic activity and metallogenenic response during this tectonic evolution are also undefined. The present paper reports new geochemical and chronological data of intrusive rocks in the Xilekuduke district,northern area of East Junggar. The intrusive rocks are divided into four types,including the340 Ma diorite,328 Ma monzonitic granite,325 Ma granite porphyry and 315 Ma quartz porphyry. All the four kind intrusive rocks are high-K calc-alkalic. The diorites possibly formed at late-collisional setting. The diorites are metaluminous, and have typical geochemical signatures of arc,including depletion of Nb,Ta and Ti,and without depletion of P and abnormality of δEu. The monzonitic granites and granite porphyries possibly formed at the early stage of post collisional setting. The monzonitic granites are weakly peraluminous,and have transformational geochemical signatures of arc and post-collisional granite,such as weakly possive abnormality of δEu,depletion of Nb,Ta and Ti,and medium depletion of P. The granite porphyries are weakly peraluminous,and have untypical geochemical signatures of post collisional granite,including negative Eu anomaly,the obvious depletion of Nb,Ta,Ti,P. The weakly peraluminous quartz porphyries have typical geochemical signatures of post collisional granite,including negative Eu anomaly,strong depletion of P,were possibly formed at post-collisional extension setting. Evidence that the intrusive rocks in the Xilekuduke district have low（87Sr /86Sr）iratio（ 0. 702976 to 0. 704306） and positive εNd（ t） values（ ＋ 5. 8 to ＋ 6. 8） with tDMages ranging from 524 Ma to 588 Ma suggests that they were possibly derived from p

关 键 词：构造演化 岩浆活动 晚碰撞 后碰撞 希勒库都克 新疆 

分 类 号：P618.570.2[天文地球—矿床学]