地质学报2025，Vol.99Issue(4)：1185-1208,中插11-中插20,34.DOI:10.19762/j.cnki.dizhixuebao.2023514
北秦岭构造带东段官坡地区花岗伟晶岩锆石U-Pb年代学、岩石成因及其构造背景
Zircon U-Pb geochronology,petrogenesis and tectonic setting of granitic pegmatite in Guanpo area,the eastern part of the North Qinling orogenic belt
摘要
Abstract
The granitic pegmatites in the North Qinling tectonic belt represent one of China's most significant pegmatite areas.However,their formation age and petrogenesis remain subjects of debate.This paper presents LA-ICP-MS zircon U-Pb ages,Hf isotopic data,and geochemical analyses of the Xiahecun and Shanghecun granitic pegmatites in the Guanpo area toconstrain their formation ages,magma sources,petrogenesis,and tectonic setting.LA-ICP-MS zircon U-Pb dating reveals that the Xiahecun and Shanghecun granitic pegmatites crystallized at 361～～360 Ma and 334.8 Ma,respectively.Both pegmatites contain garnet,muscovite,and tourmaline,with high SiO2,Na2O,and K2O contents but low CaO,TFeO,and MgO concentrations,exhibiting a mainly peraluminous composition.They display little fractionation between LREE and HREE and exhibit obvious positive Eu anomalies.The magmas are enriched in large ion lithophile elements(LILEs;e.g.,Rb,Th,Ba,and Cs)but depleted in high field strength elements(HFSE;i.e.,Nb,Ta,and Ti),with low Nb/Ta and Zr/Hf ratios,indicating a high degree of crystallization differentiation.The Xiahecun granitic pegmatite has low εHf values(-11.7 to-6.2),whereas the Shanghecun granitic pegmatite shows higher εHf values(-4.9 to 1.1).These findings imply that the Xiahecun granitic pegmatite originated from partial melting of ancient crust,while the Shanghecun granitic pegmatite formed through partial melting of juvenile lower crust,followed by magma assimilation and wall-rock contamination.In the eastern part of the North Qinling tectonic belt,the granitic pegmatites can be divided into two types:northern rare-metal granitic pegmatites and southern uranium-bearing granitic pegmatites.关键词
花岗伟晶岩/微量元素/岩石成因/岩浆演化/北秦岭Key words
granitic pegmatite/trace element/petrogenesis/magma evolution/North Qinling引用本文复制引用
陈国超,张晓飞,裴先治,李佐臣,李瑞保,王硕,陈孝珍,张荣臻,王永强..北秦岭构造带东段官坡地区花岗伟晶岩锆石U-Pb年代学、岩石成因及其构造背景[J].地质学报,2025,99(4):1185-1208,中插11-中插20,34.基金项目
本文为国家自然科学基金项目(编号42472272,42172236)、中国地质调查局项目(编号DD20190570,DD20230053,DD20230355)、河南省自然科学基金项目(编号252300421472)、有色金属成矿预测与地质环境监测教育部重点实验室开放基金项目(编号2024YSJS01)、河南省战略性金属矿产成矿规律与找矿预测研究项目(编号2023-903-XM006)和南阳理工学院交叉科学研究项目(编号24NGJY014)资助的成果. （编号42472272,42172236）
