皖南歙县水竹坑和南源口片麻状花岗闪长岩成因及其地质意义  

Petrogenesis and geological significance of Shuizhukeng and Nanyuankougneissic granodiorite in Shexian County of South Anhui

作　　者：臧政博 李双[1,2] 马莉燕[1,2] 杨晓勇 孙卫东[6] ZANG Zhengbo;LI Shuang;MA Liyan;YANG Xiaoyong;SUN Weidong(Guangxi Key Laboratory of Hidden Metallic Ore Deposits Exploration,College of Earth Science,Guilin University of Technology,Guilin 541006,Guangxi,China;Harbin Observation and Research Station of Earth Critical Zone in Black Soil,Ministry of Natural Resources,Harbin 150086,Heilongjiang,China;Harbin Center for Integrated Natural Resources Survey,CGS,Harbin 150086,Heilongjiang,China;Key Laboratory of Crust-Mantle Materials and Environment,School of Earth and Space Sciences,University of Science and Technology of China,Hefei 230026,Anhui,China;Deep Sea Research Center,Institute of Oceanology,Chinese Academy of Sciences,Shandong Qingdao 266071,Shandong,China)

机构地区：[1]桂林理工大学广西隐伏金属矿产勘查重点实验室,广西桂林541006 [2]桂林理工大学地球科学学院,广西桂林541006 [3]自然资源部哈尔滨黑土地地球关键带野外科学观测研究站,黑龙江哈尔滨150086 [4]中国地质调查局哈尔滨自然资源综合调查中心,黑龙江哈尔滨150086 [5]中国科学院壳幔物质与环境重点实验室,中国科学技术大学地球与空间科学学院,合肥230026 [6]中国科学院海洋研究所,深海研究中心,山东青岛266071

出　　处：《矿产与地质》2025年第1期124-139,共16页Mineral Resources and Geology

基　　金：国家自然科学基金项目(编号:41803038);广西自然科学基金项目(编号:2022GXNSFBA035588)共同资助。

摘　　要：皖南歙县水竹坑和南源口岩体位于江南造山带北东部,分列于伏川蛇绿混杂岩带两端。该区岩体属于片麻状花岗闪长岩。歙县岩体受皖浙赣断裂和一系列次级断裂构造影响,具有较好的成矿潜力。通过锆石U-Pb定年测得水竹坑岩体206 Pb/238 U加权平均年龄为832±11 Ma(MSWD=4.3,n=20),南源口岩体206 Pb/238 U加权平均年龄为830.2±9.4 Ma(MSWD=2.1,n=15),表明两个岩体形成于新元古代时期。歙县水竹坑和南源口片麻状花岗闪长岩的铝饱和指数A/CNK比值为1.24~1.66,具有强过铝质特征,属于S型花岗质岩石。该区水竹坑和南源口片麻状花岗闪长岩具有中等的Eu负异常,Eu N/Eu N*值为0.50~0.73,表明成岩源区具有斜长石残留。两个岩体均由变质泥岩和变质砂岩部分熔融形成。岩体的W元素的含量远大于地壳中的W含量,推测该区成矿前景良好。Shuizhukeng and Nanyuankou rock masses in Shexian county of South Anhui are located in the northeast of the Jiangnan orogenic belt,and at both ends of the Fuchuan ophiolitic mélange belt respectively.The rock mass in this area belongs to gneiss granodiorite.The Shexian rock mass is influenced by the Anhui-Zhejiang-Jiangxi fault and a series of secondary fault structures,with a good mineralization potential.According to zircon U-Pb dating result,the weighted average age of 206 Pb/238 U for Shuizhukeng rock mass is 832±11 Ma(MSWD=4.3,n=20),and the weighted average age of 206 Pb/238 U for Nanyuankou rock mass is 830.2±9.4 Ma(MSWD=2.1,n=15),which indicates these rock masses are formed during Neo-proterozoic.The aluminum saturation indices of A/CNK ratio for Shuizhukeng and Nanyuankou gneissic granodiorite are from 1.24 to 1.66,showing strongly peraluminous characteristics,and belong to S-type granitic rock.Shuizhukeng and Nanyuankou gneissic granodiorite show moderate negative Eu anomaly,with EuN/EuN*values from 0.50 to 0.73,which indicates plagioclase residue in the source area.These two rock masses are mainly formed by partial melting of metamorphic mudstone and metamorphic sandstone.The contents of W element in these two rock masses are much higher than that in the crust,indicating there is a promising mineralization prospect in this area.

关 键 词：江南造山带 新元古代 片麻状花岗闪长岩 锆石U-PB定年 安徽歙县 

分 类 号：P588.12[天文地球—岩石学]