徐宿弧安徽北段杨桥孜金铜矿床岩浆岩成因:年代学、地球化学和Hf同位素证据  

Petrogenesis of igneous rocks in the Yangqiaozi gold-copper deposit at the northern Anhui section of Xu-Su arcuate structural region:evidence from chronology, geochemistry and Hf isotopes

作　　者：韦帅 杨治 邓宇峰[1,2,3] 毛思斌 程培生 产思维[5] 袁峰 王乐乐[6] WEI Shuai;YANG Zhi;DENG Yufeng;MAO Sibin;CHENG Peisheng;CHAN Siwei;YUAN Feng;WANG Lele(School of Resources and Environmental Engineering,Hefei University of Technology,Hefei,Anhui 230009,China;Ore Deposit and Exploration Center(ODEC),Hefei University of Technology Hefei,Anhui 230009,China;Province Engineering Research Center for Mineral Resources and Mine Environments,Hefei,Anhui 230009,China;Geological Team 916 of Jiangxi Geology&Mineral Exploration Bureau,Jiujiang,Jiangxi 332100,China;Geological Exploration Technology Institute of Anhui Province,Hefei,Anhui 230009,China;Geological Team 325 of Anhui Provincial Bureau of Geology and Mineral Exploration,Huaibei,Anhui 235000,China)

机构地区：[1]合肥工业大学资源与环境工程学院,安徽合肥230009 [2]合肥工业大学矿床成因与勘查技术研究中心,安徽合肥230009 [3]安徽省矿产资源与矿山环境工程技术研究中心,安徽合肥230009 [4]江西省地质矿产勘查开发局九一六大队,江西九江332100 [5]安徽省勘查技术院,安徽合肥230009 [6]安徽省地质矿产勘查局三二五地质队,安徽淮北235000

出　　处：《地质学报》2022年第11期3867-3885,共19页Acta Geologica Sinica

基　　金：第二次青藏高原综合科学考察研究(编号2019QZKK0708);国家自然科学基金项目(编号U1803113);中国地质调查项目(编号DD20190043);安徽省自然资源科技项目(编号2020-K-14)联合资助的成果。

摘　　要：徐宿弧安徽北段地区是华北克拉通南缘重要的金属资源产区,其中三铺复式岩体北部接触带中段杨桥孜金铜矿床是安徽北部已探明的最大金矿床。本次工作针对杨桥孜矿区含矿的石英二长闪长岩与不含矿的石英二长闪长玢岩展开工作,两者的LA-ICP-MS锆石U-Pb加权平均年龄分别为128±1.1 Ma、119.9±4.3 Ma,两者都形成于早白垩世早期华北克拉通构造活动与岩浆活动峰期。岩石地球化学分析表明,杨桥孜矿区两种岩石都具有高硅、富碱、富集LREE、富Sr、贫Th和Yb的特征,属高钾钙碱性准铝质I型花岗岩;高Sr/Y、低HREE和Y、无明显Eu异常表明其具有埃达克岩的特征。石英二长闪长岩的锆石ε_(Hf)(t)为-16.3~-5.3,二阶段模式年龄(t_(DM2))为2202~1515 Ma,与石英二长闪长岩和石英二长闪长玢岩锆石核部得到的年龄范围一致,表明华北克拉通下地壳是岩浆源区的重要端元,较大的εHf(t)变化范围指示源区混合了幔源岩浆。中生代古太平洋斜向俯冲,导致华北克拉通下地壳拆沉并发生部分熔融,俯冲的洋壳板片扰动软流圈导致岩石圈地幔部分熔融,幔源岩浆与古老下地壳相互作用形成了石英二长闪长岩和石英二长闪长玢岩的母岩浆。这一成因模式与岩石中高Mg^(#)、高La/Ta、低Th/Ce、低Sr/Y、低(La/Yb)N的特征相吻合。两种岩石锆石结晶温度平均分别为742℃、708℃,氧逸度ΔFMQ平均分别为+1.79和+1.48,石英二长闪长岩具有相对较高氧逸度是其成矿的重要因素。The northern Anhui section of the Xu-Su arcuate structural region is an important metal resource producing base in the southern margin of the North China Craton. The Yangqiaozi gold-copper deposit in the middle part of the northern contact zone of the Sanpu complex is the largest gold deposit in northern Anhui so far. This work focuses on the ore-bearing quartz monzodiorite and the non-mineralization quartz monzodiorite porphyrite in the Yangqiaozi mining area. The LA-ICP-MS zircon U-Pb weighted average ages of the two intrusive rocks are 128±1.1 Ma and 119.9±4.3 Ma, respectively, both of which were formed during the tectonic and magmatic peak periods of the North China Craton in the early Early Cretaceous. Geochemical compositions show that the intrusive rocks in the Yangqiaozi deposit are characterized by high silicon, alkali, LREE, Sr, low Th, Yb content, and belong to the high-potassium calcium-alkaline meta-aluminum I type granite. High Sr/Y, low HREE and Y, and no obvious Eu anomalies which indicate that it is similar to the characteristics of adakites. The zircon ε_(Hf)(t) of the quartz monzodiorite is-16.3~-5.3, and the second-stage model age(t_(DM2)) is 2202~1515 Ma, which is consistent with the age range of the zircon core, indicating that the lower crust of the North China Craton is an important end member of the magma source. Moreover, large εHf(t) variation range indicates that the magma source is mixed with mantle-derived magma. The oblique subduction of the Paleo-Pacific Ocean in the Mesozoic led to delamination and partial melting of the lower crust in the North China Craton. The subduction of oceanic crust slabs disturbed the asthenosphere, caused partial melting of the lithospheric mantle, and produced mantle-derived magma. The interaction of themantle-derived magma and the lower crust formed the parental magma of the quartz monzodiorite and the quartz monzodiorite porphyrite. This genetic model is consistent with the high Mg^(#)and La/Ta, low Th/Ce, Sr/Y and(La/Yb)Nratios of the intrusive r

关 键 词：杨桥孜金铜矿床 地球化学特征 锆石年代学 HF同位素 氧逸度 

分 类 号：P618.51[天文地球—矿床学] P618.41[天文地球—地质学]