江山—绍兴结合带榴闪岩的发现及岩石学、年代学特征

The discovery, petrology and geochronology of the retrograde eclogite in Jiangshan-Shaoxing suture zone

摘要: 提要：江山—绍兴结合带内浙江溪口一带发现了以岩块、透镜状产出的榴闪岩。榴闪岩主要由角闪石、石榴子石、单斜辉石、斜长石和石英组成，以石榴子石为中心“白眼圈”结构明显，镜下可见石榴子石周围斜长石冠状体，单斜辉石内部及周围由斜长石和角闪石构成的后成合晶与冠状体结构。通过锆石LA-ICP-MS U-Pb测年在白石山头榴闪岩中获得主要变质年龄（451+8/-18） Ma。江山—绍兴结合带榴闪岩的发现为研究华夏地块与扬子陆块之间碰撞拼贴历史提供了新证据。

Abstract: Abstract: This paper reports retrograde eclogite that occurs in lanticular form in Xikou area of Jiangshan-Shaoxing suture zone. The retrograde eclogite consists of the mineral assemblage of amphibole+garnet+clinopyroxene+plagioclase+quartz. A clear ‘white-eye' structure is well developed, garnet is rimmed with symplectitic plagioclase, and clinopyroxene is surrounded by symplektic plagioclase and amphibole. Zircon U-Pb dating by LA-ICP-MS shows that the peak metamorphic age is （451+8/-18）Ma. Exposures of retrograde eclogites in the Jiangshan—Shaoxing suture zone provide new insight for the collisional process between the Cathaysia block and the Yangtze block.