兴蒙造山带南缘东段延边和龙地区晚二叠世-三叠纪侵入岩成因及构造变形研究

Helong Area is located at the contact of the eastern segment of northern margin of North China Craton and eastern segment of the southern margin of the Xing'an–Mongolia Orogenic Belt, and is the key part for discussing the tectonic evolution of Paleo-Asian oceanic and Paleo-Pacific tectonic domains. The late Palaeozoic-early Mesozoic igneous rocks are distributed widely in this area and are considered as magmatism during subduction, collision and post-collision orogeny process, while the multiple phases of deformation occurred in the late Permian-Triassic igenous rocks are also recognized as the important records of orogeny. However, the study of petrogenesis and tectonic deformation of late Permian -Triassic igneous rock in Helong area, could provide the evidences for the late Palaeozoic-early Mesozoic geological evolution in Yanbian area. With the methods of chronology, petrogeochemistry, and zircon Hf-O isotope, we study the petrogenesis and tectonic setting of intrusive rocks and anlyse the features of tectonic deformation in the study in order to provide the proofs for discussing the tectonic evolution of late Palaeozoic-early Mesozoic in eastern segment of the southern margin of the Xing'an–Mongolia Orogenic Belt.

和龙地区位于兴蒙造山带南缘东段和华北克拉通北缘交接部位，是研究古亚洲洋构造域与古太平洋构造域演化的关键区域。该区发育晚古生代-早中生代岩浆岩，保留了完整的俯冲-碰撞-碰撞后造山过程的岩浆活动记录，而晚二叠世-早三叠世岩浆岩中发生的多期构造变形是造山过程的重要构造记录。和龙地区晚二叠世-三叠纪岩浆岩成因及构造变形研究可以探明延边地区晚古生代-早中生代的构造演化历程。本项目用同位素年代学、岩石地球化学和锆石Hf-O同位素等方法分析研究区侵入岩成因及构造背景，并对侵入岩构造变形进行构造解析，为探讨兴蒙造山带南缘东段晚古生代-早中生代构造演化提供依据。

延边和龙地区位于兴蒙造山带南缘东段和华北克拉通北缘交接部位，是研究探讨古亚洲洋与古太平洋构造域演化的理想区域。该区发育的晚二叠世-三叠纪侵入岩及构造变形带是造山带构造演化的重要物质记录，因此系统研究延边和龙地区晚二叠世-三叠纪侵入岩时空分布规律、岩石组合特征、岩浆源区性质、岩石成因及构造变形特征，可以明确该区晚古生代-早中生代构造演化历程，同时为古亚洲洋和古太平洋构造域的构造演化过程提供重要科学依据。.项目以延边和龙地区晚二叠世-三叠纪侵入岩及其中的构造变形带为主要研究主体，建立延边和龙地区晚二叠世-三叠纪侵入岩年代学格架，依据年代学、岩石地球化学、锆石Hf同位素分析，延边地区晚二叠世-三叠纪岩浆活动主要包括晚二叠世具有俯冲特点的石英闪长岩和黑云母闪长岩，具有双峰式岩浆岩特征的早三叠世花岗岩和闪长岩，具有埃达克岩性质的中三叠世花岗岩；此外，本项目对研究区内古洞河韧性剪切带进行了构造解析，识别出两期韧性变形构造，早期韧性变形发育在早-中三叠世岩浆岩中，并被晚期韧性变形强烈叠加改造，利用同构造脉锆石U-Pb年龄和黑云母40Ar-39Ar年龄限定了晚期韧性变形时间为170Ma-180Ma。.在此基础上，总结分析研究区晚二叠世-三叠纪侵入岩成因及古洞河韧性变形特征在兴蒙造山带南缘东段晚古生代-早中生代构造演化过程中所起的作用，综合前期研究成果，明确和龙地区晚二叠世-三叠纪的构造演化过程，为探讨古亚洲洋的最终闭合和古太平洋构造域的叠加作用提供了重要科学依据。