Tectonic environment of basic volcanic rocks in the Hongshishan ophiolite mélange zone, Beishan Mountains, Gansu

Abstract：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 REE) 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.