伊朗乌尔米亚大学Modjarrad Monir小组近日取得一项新成果。经过不懈努力，他们揭示了伊朗西北部盖辛蛇绿岩的岩石学演化。该项研究成果发表在2024年3月28日出版的《地球化学学报》上。

盖辛蛇绿岩中的蛇纹石化橄榄岩含有蛇纹石+温石棉+尖晶石/镁尖晶石组合，带有残余单斜辉石(透辉石)和非常罕见的残余斜方辉石和橄榄石。单斜辉石和尖晶石的成分更符合推断的弧前或超俯冲带原岩方辉橄榄石的形成，而不是深海环境。

盖辛蛇绿岩是新特提斯弧-蛇绿岩体系的残余，记录了晚白垩世至古新世，沿大陆边缘的岩浆断层逆冲上冲之前的浅俯冲作用(<50 km，由叶蛇纹石的缺失表示)。研究回顾了该地区新特提斯蛇绿岩变质程度的空间变化趋势，并提供了盖辛蛇绿岩的岩石学和矿物化学特征的详细信息。

据悉，伊朗西北部的盖辛蛇绿岩位于土耳其东南部、伊拉克东北部和伊朗蛇绿岩带的交汇处，为研究一个重要的构造场所保存下来的俯冲和逆冲历史提供了机会，这是以前没有研究过的。

附：英文原文

Title: Petrologic evolution of the Gysian ophiolitic serpentinites, NW Iran

Author: Modjarrad, Monir, Whitney, Donna L., Omrani, Hadi

Issue&Volume: 2024-03-28

Abstract: The Gysian ophiolite of NW Iran is located at the intersection of the ophiolite belts of SE Turkey, NE Iraq, and Iran, and provides the opportunity to investigate the preserved subduction and obduction history of an important tectonic site that has not previously been studied. The serpentinized peridotites of the Gysian ophiolite contain the assemblage lizardite+chrysotile+spinel/Mg-spinel with relict clinopyroxene (diopside) and very rare relict orthopyroxene and olivine. The compositions of clinopyroxenes and spinels are more consistent with the formation of the inferred protolith harzburgites in a fore-arc or supra-subduction zone instead of an abyssal environment. The Gysian ophiolite is a remnant of the Neo-Tethyan arc-ophiolitic system and records shallow subduction (<50 km, indicated by the absence of antigorite) in the Late Cretaceous to Paleocene before obduction along thrust faults over the continental margin. We review the spatial trends of the metamorphic grade of the Neo-Tethyan ophiolites in this region and provide detailed information about the petrology and mineral chemistry of the Gysian ophiolite.

DOI: 10.1007/s11631-024-00682-6

Source: https://link.springer.com/article/10.1007/s11631-024-00682-6