摘要
位于商丹俯冲增生带南缘山阳–柞水地区的侵入岩类在形成时代主要集中在新元古代(885~621 Ma)和中晚三叠—早白垩世(233~132 Ma)2个阶段,且后者多为秦岭造山带印支期—燕山期造山活动的产物。该构造带内土地沟至池沟地区出露有部分与成矿作用有关的小岩体,锆石LA–ICP MS U–Pb同位素测年结果表明其形成时代为144.4~158.8 Ma,属于晚侏罗世—早白垩世侵入岩类。岩石地球化学特征显示出富集大离子亲石元素,亏损高场强元素,高Sr、低Y的特征。结合区域岩浆岩演化研究,可以认为土地沟–池沟地区晚侏罗—早白垩世侵入岩类的形成可能与西太平洋活动应力作用以及区内的北西向构造系统约束具有密切关联。受此影响,以中南秦岭地区在后碰撞–后造山阶段拆沉和幔源物质上涌作用下,地壳物质发生重熔从而在山阳–柞水一带形成一系列中酸性侵入岩类。
Located in the south margin of Shangdan sunduction–accretion belt,intrusive rocks in Shanyang–Zhashui region are mainly formed in two stages:the former is Neoproterozoic(885~621 Ma),and the latter is Middle–Late Triassic and Early Cretaceous(233~132 Ma)that was a result of Qinling orogenic event during Indosinian-Yanshan period.Zirons LA-ICP-MS U-Pb dating of intrusions in Tudigou-Chigou region show them formed between 144.4 Ma and 158.8 Ma,during Late Jurassic and Early Cretaceous.Geochemical study on these rocks reveals,they are enriched in large ion lithophile element(LILE)and depleted in high field strength elements(HFSE),with a high ratio of Sr/Y.Combined with the research on regional magmatic evolu-tion,intrusions formed between Late Jurassic and Early Cretaceous in Tudigou and Chigou may be controlled by the movement of western Pacific and NE faults.And also,with the crustal delamination and the addition of fluid from subduction-accretion belt in post-collision and post-orogenic stages,intrusions from Shanyang-Zhashui region are formed by the melting of crust in Middle-south Qinling.
作者
李平
陈隽璐
张越
孙少珍
郝晨羽
LI Ping;CHEN Junlu;ZHANG Yue;SUN Shaozhen;HAO Chenyu(Xi’an Center of China Geological Survey/Center for Orogenic Belt Geology of CGS,Xi’an 710054,Shaanxi,China;Center of Urumqi Natural Resources Comprehensive Survey,CGS,Urumqi 830057,Xinjiang,China;Xi’an Northwest Nonferrous Geophysical and Geochemical Exploration Co.Ltd.,Xi’an 710068,Shaanxi,China;Shaanxi Mineral Resources and Geological Survey,Xi’an 710068,Shaanxi,China)
出处
《西北地质》
CAS
CSCD
北大核心
2023年第2期10-27,共18页
Northwestern Geology
基金
中国地质调查局项目“秦岭祁连地区区域地质调查”(DD20230215)
“北方造山带重要地区区域地质调查工程”(DD20230005)
“西北地区铜镍钴等战略性矿产资源调查”(DD20230032)
“西北重大岩浆事件及其成矿作用和构造背景综合研究”(12120114020501)
“西北地区自然资源动态监测与风险评估”(DD20211393)联合资助。
