华北克拉通南缘箕山地区新太古代末期地壳演化——来自叶寨花岗岩年代学和地球化学证据  

Late Neoarchean Crustal Evolution of Jishan Area in the Southern Margin of North China Craton:Insights from Geochronology and Geochemistry of Yezhai Granite

作　　者：郭晓伟 杨延伟 张宇 GUO Xiaowei;YANG Yanwei;ZHANG Yu(Henan First Resources and Environment Investigation Investigation Institute Co.,ltd,Zhengzhou,Henan 450000,China;Henan Academy of Geology,Zhengzhou,Henan 450001,China)

机构地区：[1]河南省资源环境调查一院有限公司,河南郑州450000 [2]河南省地质研究院,河南郑州450001

出　　处：《现代地质》2025年第1期83-95,共13页Geoscience

基　　金：河南省国土资源厅2016年度基础性地质环境调查项目(2015-2077-1号)。

摘　　要：嵩箕地区位于华北克拉通南缘,广泛发育新太古代TTG片麻岩和花岗岩,是深入研究华北克拉通早前寒武纪地质演化的重要窗口。为加深对箕山地区前寒武纪地壳演化的理解,本文选择新识别的登封杂岩叶寨花岗岩体为研究对象,开展了系统的锆石U-Pb年代学和全岩元素组成分析,以确定其形成时代、成因及构造演化过程。研究结果显示,叶寨花岗岩体锆石U-Pb谐和线上交点年龄为(2506±19)Ma,标志着其形成于新太古代末期。岩石表现出相对高硅(SiO_(2)=66.88%~74.14%)和富碱(Na_(2)O=3.15%~4.09%;K_(2)O=2.06%~5.36%)特征,表明其为过铝质的钙碱性至高钾钙碱性特征(A/CNK=1.03~1.27)。稀土元素分布模式显示轻稀土元素(LREE)显著富集,而重稀土元素(HREE)相对亏损,表现出不明显或弱正铕异常(δEu=0.76~1.26)。微量元素数据表明,岩石富集大离子亲石元素(如Rb、U、Th和K),同时相对亏损高场强元素(如Nb、Ti和P)。微量元素图解分析进一步揭示,叶寨花岗岩体具有高Sr、低Yb和Y的特征,Sr/Y值为22.76~123.81,接近埃达克岩的地球化学特征。综合微量元素间的关系及稀土元素特征,本文认为叶寨花岗岩体形成于岛弧构造环境,可能是由下伏幔源岩浆引发的上覆加厚下地壳部分熔融所致。这些发现为认识华北克拉通南缘的构造演化及岩浆活动提供了基础性地质证据。The Songji area,located on the southern margin of the North China Craton,is characterized by the extensive presence of Neoarchean TTG gneiss and granite,making it a vital window for studying the early Precambrian geological evolution of the North China Craton.This study focuses on the newly identified Yezhai granite body within the Dengfeng Complex,employing geochronological and geochemical analyses to ascertain its formation age,genesis and tectonic evolution.The zircon U-Pb age of the Yezhai granite is determined to be(2,506±19)Ma,indicating its formation during the late Neoarchean period.Geochemical investigations reveal that the rock mass exhibits relatively high silica content(SiO_(2)=66.88%-74.14%)and is enriched in alkali elements(Na_(2)O=3.15%-4.09%;K_(2)O=2.06%-5.36%),demonstrating peraluminous calc-alkaline to high-potassium calc-alkaline characteristics(A/CNK=1.03-1.27).The rare earth elemental distribution pattern shows a right-leaning tendency,characterized by the enrichment of light rare earth elements(LREE)and depletion of heavy rare earth elements(HREE),along with a weak or inconspicuous positive europium anomaly(δEu=0.76-1.26).Trace element analysis indicates the enrichment of large ion lithophile elements(Rb,U,Th,K)and relative depletion of high field strength elements(Nb,Ti,P).The trace elements diagrams highlight features of high strontium(Sr)and low Yb and Y,with Sr/Y ratios ranging from 22.76 to 123.81,resembling the geochemical characteristics of adakite.The relationship among Nb,Y,Rb and Yb suggest similarities with island arc volcanic rocks.Overall,the findings indicate that the Yezhai granite body in Jishan area likely formed in an island arc setting,potentially resulting from the partial melting of an older,thickened lower crust in the Songji region.

关 键 词：二长花岗岩 前寒武纪 锆石U-PB定年 嵩箕地区 华北克拉通 

分 类 号：P588.115[天文地球—岩石学] P591.1[天文地球—地质学]