地球学报2025，Vol.46Issue(4)：760-776,17.DOI:10.3975/cagsb.2025.032402
金沙江造山带印支期碰撞造山作用过程
Constraints on the Indosinian Orogeny in the Jinshajiang Orogenic Process:Evidence from the Deformation Characteristics and Geochronological Results of the Xulong Ductile Shear Zone in Yangla Town
摘要
Abstract
Study of the subduction-collision orogeny timescale of the Jinshajiang Orogenic Belt is crucial for understanding the evolution of the eastern Paleo-Tethys Orogeny.It provides an accurate tectonic background and insights into the Indosinian porphyry-skarn metallogenic system(such as the Yungla copper deposit)in theorogenic belt.This study selected the Xulong hydropower station ductile shear zone of Yangla town in the middle section of the Jinsha River Suture Zone to perform a field investigation and microstructural kinematic and geometric analysis.In addition,this study utilized zircon LA-ICP MS U-Pb dating of the deformed,weakly deformed,and undeformed granodiorite and 40Ar/39Ar isotopic thermochronology on biotite to determine the magmatic emplacement and metamorphic deformation ages in the ductile shear zone.We suggest that the Xulong ductile shear zone trends in the NEE-SWW direction,has a gentle occurrence,and undergoes nearly S-N directed shearing.Field results and microstructures indicate that this ductile shear zone exhibits dextral extensional characteristics.Zircon 206Pb/238U crystallization ages of 285 Ma,259.5 Ma,and 226.4 Ma were obtained from the deformed granitic gneiss within the shear zone,the weakly deformed Maoding granodiorite,and the undeformed Jiaren granodiorite,respectively.Additionally,biotite in the deformed granitic gneiss yielded an 40Ar/39Ar isotopic metamorphic-deformational plateau age of(223.75±2.18)Ma,indicating that the deformation age of the Xulong ductile shear zone is Late Triassic.The study concluded that the middle section of the Jinsha River Orogenic Belt underwent the evolution process of rifted basin(D),ocean basin expansion(C1-P1),oceanic crust expansion-subduction(283-279 Ma),collisional orogeny(269-259 Ma),late collisional extensional orogeny(223-231 Ma),and post-collision(215-200 Ma).Among these,the Late Triassic metamorphic-deformation age of the Xulong ductile shear zone is the product of the late collisional extrusion-extension tectonic transition stage of the Jinsha River continent-continent collisional orogeny.关键词
金沙江缝合带中段/旭龙韧性剪切带/印支期/黑云母 40Ar/39Ar同位素测年/锆石U-Pb测年Key words
middle section of the Jinsha River Suture Zone/Xulong ductile shear zone/Indosinian Period/biotite 40Ar/39Ar isotopic dating/zircon U-Pb dating分类
天文与地球科学引用本文复制引用
张圣超,朱政坤,江小均,黄应才,刘小青,刘凤泽,李雨健,韩嶂,严清高..金沙江造山带印支期碰撞造山作用过程[J].地球学报,2025,46(4):760-776,17.基金项目
本文由国家自然科学基金项目(编号:42462011)、云南省科技厅高层次科技人才及创新团队选拔专项(编号:202305AT350004)和校企合作项目(编号:202404YKKC007)联合资助. This study was supported by National Natural Science Foundation of China(No.42462011),Yunnan Provincial Science and Technology Department(No.202305AT350004),and School-Enterprise Cooperation Project(No.202404YKKC007). （编号:42462011）
