浙江龙游地区基性及镁质变质岩的地球化学特征及其构造环境

位于扬子陆块东南缘与华夏地块之间的龙游地区出露一套中深变质岩系，其对华南前泥盆纪地质构造格局问题的解释至关重要，但目前人们对其形成时的大地构造背景了解不多.通过对其中的基性及镁质变质岩进行系统的岩石地球化学研究，可将这些岩石可以分为3种类型:“N-MORB”型、“T-MORB”型和“E-MORB”型.其中“N-MORB”型岩石原岩可能主要形成于洋内弧环境，“T-MORB”型岩石原岩主要形成于过渡型大洋中脊及火山弧环境，而“E-MORB”型岩石的原岩则主要形成于富集型大洋中脊、陆缘弧和板内环境.岩石成岩环境的多样性表明龙游地区的变质岩实属一套构造混杂岩，形成过程与古大洋地壳的俯冲、消减有关，这也为龙游榴闪岩的产出、定位提供了合理的解释. 

Geochemical Characteristics of the Basic and Magnesian Metamorphic Rocks in Longyou Area,Zhejiang Province and Their Tectonic Setting

A medium and high grade metamorphic rock series is exposed in Longyou area located in the southeast margin of Yangtze block and Cathaysia block, which is important for the interpretation of South China Predevonian tectonic pattern. But the tectonic setting of its formation remains unknown presently. It is found out these rocks can be divided into three types: "N-MORB", "T-MORB" and "E-MORB" type rock by a basic and magnesian metamorphic rock geochemical study in this paper The protoliths of the "N-MORB" is mainly formed in the intra-oceanic arc, the "T-MORB" is mainly formed in the transition of mid-oceanic ridge and the volcanic arc, and the "E-MORB" type rock is formed in the enrichment of mid-oceanic ridge, epicontinental arc and intraplate environment. Rock diagenesis environment diversity shows that the metamorphic rock of Longyou area is a tectonic mélange and its forming process is related with the ancient oceanic crust subduction, which also provides a reasonable explanation for the output, positioning of the pomegranate amphibolite in Longyou area.