江南造山带东段鄣源枕状玄武岩的年代学与构造属性研究  

Study on geochronology and structural properties of pillow basalts in Zhangyuan region,eastern section of the Jiangnan orogen

作　　者：周效华[1,2] 高天山[2] 马雪[2] 张彦杰[2] 廖圣兵[2] 余明刚[2] 陈丹丹[2] 朱延辉[2] 

机构地区：[1]南京大学地球科学与工程学院,南京210093 [2]南京地质矿产研究所,南京210016

出　　处：《资源调查与环境》2014年第4期235-244,共10页Resources Survey & Environment

基　　金："江南造山带东段新元古代沟弧盆体系演化与大陆生长研究"项目(12120114039001);"扬子地块东南缘河上镇群地层划分及沉积岩相古地理研究"项目(1212011121107);中国地质调查局"安徽1:5万平里;江潭;瑶里;虹关幅区调"项目(1212010610609)资助

摘　　要：江南造山带东段鄣源地区广泛发育呈构造岩块产出的镁铁质岩浆岩,包括空间上密切共生的蚀变枕状-块状玄武岩、辉长岩、辉绿岩等。玄武岩地球化学特征上总体富集轻稀土,亏损重稀土和高场强元素(Nb,P,Ti),类似于岛弧环境下岩浆活动的产物。SHRIMP锆石U-Pb测年结果显示,枕状玄武岩形成于(832±19)Ma,与伏川蛇绿岩和庐山地区枕状玄武岩形成时代一致。结合区域资料,认为鄣源枕状玄武岩形成于弧后小洋盆环境,与其东侧的伏川蛇绿岩和西侧的庐山地区枕状熔岩同属新元古代中期弧后洋盆的产物。The mafic magmatic rocks that are shown as tectonic blocks are extensively developed in Zhangyuan region, eastern section of the Jiangnan orogen, including the closely spatially associated altered pillow- massive basalts, gabbros, diabases, etc. In geochemical composition, these volcanic rocks domina- ted are enriched in LREE and depleted in HREE and high field strength elements （Nb,P and Ti）, being similar to the product of island arc magmatism. SHRIMP zircon U-Pb dating shows that the pillow basalts were formed at （832±19） Ma, that consistents with the age of Fuchuan ophiolites and pillow basalts in Lushan area. Combining regional informations, pillow basalts are considered to be formed in a small back- arc oceanic basin environment in middle Neoproterozoic. Together with Fuchuan ophiolites and Lushan pil- low lavas distributed respectively in the east and west sides of Zhangyuan pillow basalts, they are the same product of back-arc oceanic basins in middle Neoproterozoic.

关 键 词：枕状玄武岩 锆石U-PB年龄 新元古代 江南造山带 

分 类 号：P588.145[天文地球—岩石学]