甘肃北山红石山蛇绿混杂岩带中基性火山岩构造环境分析

Tectonic environment of basic volcanic rocks in the Hongshishan ophiolite mlange zone, Beishan Mountains, Gansu

红石山基性火山岩为红石山蛇绿岩的重要组成单元之一,有关其形成的构造环境一直存在分歧,因此影响了对该蛇绿岩的性质、形成和演化方面的深入研究,笔者在野外对红石山一带的基性火山岩地质特征进行了详细的观察,在结合前人研究资料的基础上,利用地球化学(主量、微量及稀土元素)及Sm-Nd同位素分析等对其构造背景进行了多种手段相结合的判断和分析,确定红石山蛇绿岩其形成于洋中脊环境,时代定为早石炭世。

Basic volcanic rocks in Hongshishan are one of the important components of the Hongshishan ophiolite. So far different views exist as to their tectonic environment, thus affecting the deep-going study of the nature, origin and evolution of the ophiolite. The authors conducted detailed field observations of the geological characteristics of the basic volcanic rocks in Hongshishan and used geochemical （major element, trace element and ILEE） data from XRF, ICP-MS and Sm/Nd isotope analysis as well as the previous data to make an integrated discrimination and analysis of their tectonic environment. It was determined that the basic volcanic rocks formed in a MORB tectonic environment, which provides new evidence for the environment of the Hongshishan ophiolite.