地质科学2025，Vol.60Issue(4)：1042-1055,14.DOI:10.12017/dzkx.2025.068
中祁连热水大坂地区寒武纪埃达克岩:对北祁连洋俯冲的启示
Cambrian adakite in the Reshuidaban area of the middle Qilian Mountains:Implications for subduction of the North Qilian Ocean
摘要
Abstract
The Qilian orogenic belt has been in a subduction environment since the Cambrian-Ordovician period,but the subduction polarity of the North Qilian Ocean remains controversial.This paper conducts petrological,whole-rock geochemical,LA-ICP-MS zircon U-Pb age,Lu-Hf isotopic,and Sr-Nd isotopic analyses on the granodiorite exposed in the Reshuidaban area with a large outcrop area on the northern side of the central Qilian,to explore its petrogenesis,tectonic background,and implications for the subduction polarity of the North Qilian Ocean.The granodiorite rocks in the Reshuidaban area of the middle Qilian Mountains belong to the calc-alkaline series and quasi-peraluminous rocks,and Ⅰ-type granite,LA-ICP-MS zircon U-Pb dating indicates an age of 500～496 Ma,corresponding to the Late Cambrian.The rocks are exhibit high SiO2(62.96％～67.76％),Al2O3(16.19％～17.85％),and Na2O(3.44％～4.26％).They are depleted in heavy rare earth elements,and with high Sr(1 044.39×10-6～1 235.15×10-6),Sr/Y(66.9～132.3),La(35.92×10-6～48.27×10-6),and(La/Yb)N(20.51～36.94),showing the geochemical characteristics of the adakite.The rock exhibit depleted Nd isotopic compositions with εNd(t)values ranging from-3.0 to-2.1,and magmatic zircons show εHf(t)values from-6.158 to+1.656.It is concluded that the Cambrian granodiorite of the Reshuidaban is adakite formed by partial melting of the lower crust of the overlying plate during the subduction stage of the North Qilian Ocean to the middle Qilian microcontinent,which further confirms that the North Qilian Ocean has experienced the process of subduction to the south.关键词
埃达克岩/热水大坂/寒武纪/俯冲/北祁连洋Key words
Adakite/Reshuidaban/Cambrian/Subduction/North Qilian Ocean分类
天文与地球科学引用本文复制引用
蒋成伍,薛万文,张金明,金婷婷,康继祖,王亚栋..中祁连热水大坂地区寒武纪埃达克岩:对北祁连洋俯冲的启示[J].地质科学,2025,60(4):1042-1055,14.基金项目
青海省地质矿产勘查开发局项目"青海北部铬矿成矿作用研究"(编号:[2023]33)资助 （编号:[2023]33）
