岩石矿物学杂志2026，Vol.45Issue(1)：19-45,27.DOI:10.20086/j.cnki.yskw.2026.5004
大洋俯冲和陆-陆碰撞过程中陆壳的改造与成熟
Reworking and maturation of continental crust during oceanic subduction and continental collision processes:A case study of magmatism and anatexis in Yuka area,North Qaidam
摘要
Abstract
The oceanic subduction zones and collision orogenic belts are critical regions for the evolution and matura-tion of continental crust.However,the specific mechanisms driving crustal reworking and maturation remain subjects of considerable controversy.In this study,we employ an integrated approach that combines petrography,geochemistry,zircon U-Pb geochronology,and zircon Lu-Hf isotopic analyses to analyze the felsic gneisses and their internal leu-cosomes,basic gneisses,and diorites within the Guaijiaoliang-Shuangkoushan arc-related rock unit,in order to in-vestigate the key mechanisms driving continental crust evolution in this region.Whole-rock geochemical analysis re-veals that the felsic gneisses,basic gneisses,and diorites are enriched in large ion lithophile elements and light rare earth elements,while being depleted in high field strength elements,characteristic of typical arc magmatic geo-chemical signatures.The basic and felsic gneisses exhibit a continuous evolution in major element composition,suggesting that the protolith of felsic gneisses originated from the crystallization differentiation of basic magmas.The leucosomes within the felsic gneisses exhibit high SiO2,Al2O3,and Na2O contents but low K2O,CaO,Rb/Sr,and Th/U ratios,characteristic of the geochemical features of trondhjemite,consistent with fluid-present melting.Zir-con U-Pb geochronology reveals that the protolith of basic gneiss and diorites formed at 470.9±6.5 Ma and 441.6±3.0 Ma,respectively.Hf isotopic analysis reveals that the zircon εHf(t)values of the basic gneisses range from+6.74 to+11.26,whereas the εHf(t)values of the diorites vary from+5.13 to+8.06.The leucosomes in the fel-sic gneisses crystallized at 441.6±3.5 Ma,and their zircon εHf(t)values range from+7.24 to+12.27,which is consistent with those of the basic gneisses.Comprehensive analysis indicates that the Guaijiaoliang-Shuangkoushan arc magmatic-metamorphic unit records two phases of arc magmatic activity and one phase of metamorphic-anatexis.During the～470 Ma oceanic crust subduction phase,subducted fluids facilitated partial melting of the mantle wedge,leading to the formation of the first phase of arc magmatism,i.e.,the protoliths of the basic gneisses and felsic gneisses.During the transition from oceanic subduction to continental collision at～440 Ma,the upwelling of the asthenosphere triggered partial melting of a hydrated mantle,resulting in the formation of diorites.The emplace-ment and crystallization of the diorites released heat and fluids,inducing hydrous partial melting of the felsic gneiss protolith.Both phases of arc magmatic activity and the subsequent anatexis events promoted the transformation of the continental crust from basic to acidic within the North Qaidam subduction-collision mélange belt.This suggests that arc magmatism and anatexis processes during the transition from oceanic subduction to continental collision were key factors driving the reworking and maturation of the continental crust.关键词
大陆地壳成熟/大洋俯冲/陆-陆碰撞/混合岩化/柴北缘Key words
continental crust maturation/oceanic subduction/continental collision/migmatitization/North Qaidam分类
天文与地球科学引用本文复制引用
孙雯慧,王林涛,蒋晓聪,祁钰,李传志,王越,于胜尧..大洋俯冲和陆-陆碰撞过程中陆壳的改造与成熟[J].岩石矿物学杂志,2026,45(1):19-45,27.基金项目
国家自然科学基金项目(42372247) （42372247）
泰山学者特聘专家项目(tstp20231214) Nation Natural Science Foundation of China(42372247) （tstp20231214）
Taishan Scholars Program(tstp20231214) （tstp20231214）
