胶东晚中生代花岗岩的源区性质与构造环境演化及其对金成矿的启示  

Source characteristics and tectonic evolution of Late Mesozoic granites in Jiaodong and their implications for gold mineralization

作　　者：王斌 宋明春 霍光 周明岭 徐忠华 蒋雷 宋英昕 李杰 WANG Bin;SONG Ming-chun;HUO Guang;ZHOU Ming-ling;XU Zhong-hua;JIANG Lei;SONG Ying-xin;LI Jie(Deep Gold Mine Exploration Big Data Application Development Engineering Laboratory in Shandong Province,Key Laboratory of Deep Gold Exploration and Evaluation of Shandong Provincial Bureau of Geology and Mineral Resources,Shandong Provincial No.6 Exploration Institute of Geology and Mineral Resources,Weihai 264209,China;Institute of Geological Sciences of Shandong Province,Jinan 250013,China;College of Resources,Hebei GEO University,Shijiazhuang 050031,China)

机构地区：[1]山东省深部金矿探测大数据应用开发工程实验室,山东省地矿局深部金矿勘查评价重点实验室,山东省地质矿产勘查开发局第六地质大队,山东威海264209 [2]山东省地质科学研究院,山东济南250013 [3]河北地质大学资源学院,河北石家庄050031

出　　处：《岩石矿物学杂志》2021年第2期288-320,共33页Acta Petrologica et Mineralogica

基　　金：NSFC-山东联合基金(U2006201);山东省重点研发计划(2017CXGC1604);山东省泰山学者建设工程专项经费(ts201511076);山东省地矿局科研项目(KY2018002);山东省第六地质矿产勘查院青年创新基金(DKLY201901)。

摘　　要：胶东地区位于华北板块与大别-苏鲁造山带拼合位置的东北端,晚中生代发育强烈的构造-岩浆事件,是研究区域构造活动体制转换和克拉通破坏过程的理想之地。本文以晚中生代花岗岩为研究对象,通过详细的岩相学、岩石地球化学、锆石LA-ICP-MS U-Pb年代学及Sr-Nd同位素研究,探讨了岩浆源区性质和成岩成矿的构造环境演变历史。研究结果表明,胶东地区的玲珑型花岗岩、郭家岭型花岗岩、伟德山型花岗岩的侵位时代分别为163.2~157.9、132.9~130.0和121.3~116.7 Ma,崂山型花岗岩和脉岩的侵位时代分别为125.0和120.7 Ma。由侏罗纪至早白垩世,岩石化学成分由高钾钙碱性系列→橄榄安粗岩系列,由过铝质→偏铝质;微量元素由高Ba、Sr→低Ba、Sr,由高Sr低Y→低Sr高Y;稀土元素由无或弱正铕异常→显著负铕异常;花岗岩类型由S型→Ⅰ型→A型;地幔性状由EM2型向EM1型演化,由富集地幔转向亏损地幔或由岩石圈转向软流圈演变。胶东地区晚中生代花岗岩的岩浆演化特征是深层次构造背景转换的反映,即由华北-扬子板块构造体系向欧亚-太平洋板块构造体系和由挤压机制向伸展机制的转换,在这一过程中发生的早白垩世热隆-伸展构造为胶东大规模金成矿提供了有利条件。Located at the junction of the southeastern margin of the North China Craton and the northeastern section of the Dabie-Sulu orogenic belt,the Jiaodong area is an ideal place for studying the transformation of regional tectonic mechanism and craton destruction.In this paper,the authors chose the Late Mesozoic granite as the research object,and carried out detailed petrographic,petrogeochemical,zircon LA-ICP-MS U-Pb geochronological and Sr-Nd isotope studies,focusing on the origin and evolution history of magma and geodynamic mechanism of regional diagenesis and mineralization.The results show that the emplacement ages of Jurassic continental crust remelted Linglong-type granite,Cretaceous crust-mantle mixed Guojialing-type granite and Weideshan-type granite are 163.2~157.9 Ma,132.9~130.0 Ma,and 121.3~116.7 Ma,respectively,and the emplacement ages of Cretaceous Laoshan-type granite and vein rock are 125.0 Ma and 120.7 Ma,respectively,which are basically in line with the previous age test data.From Jurassic to Early Cretaceous,the chemical composition of granites evolved from high-potassium calc-alkaline series to shoshonite series,i.e.,from peraluminous to metaluminous,trace element content evolved from high Ba-Sr to low Ba-Sr and from high Sr,low Y to low Sr and high Y,REE varied from no or weak positive Eu anomaly to significant negative Eu anomaly,and the type of granites varied from S-type to I-type and Atype.It shows the evolution trend from EM2 enriched mantle to EM1 enriched mantle,from enrichment to depletion or from lithosphere to asthenosphere.The Jiaodong area in the Late Mesozoic experienced the transformation from North China-Yangtze tectonic system to Eurasian-Pacific tectonic system and from compression mechanism to extension mechanism.The strong thermal-uplift extension structure in Early Cretaceous provided favorable conditions for large-scale gold mineralization.

关 键 词：胶东地区 晚中生代花岗岩类 地球化学特征 源区性质 构造环境演化 热隆伸展 金矿 

分 类 号：P588.121[天文地球—岩石学] P618.51[天文地球—地质学]