地质学报Issue(2)：145-166,22.
雅鲁藏布江蛇绿岩带东段泽当蛇绿岩起源及演化
The Origin and Evolution of Zedang Ophiolite in the Eastern Yarlung-Zangbo Suture Zone,Southern Tibet
摘要
Abstract
In this paper,based on a study of mineral chemistry of mantle peridotites as well as petrochemistry and geochemistry of mantle peridotitses,basalts,gabbros from Zedang ophiolite,combined with previous research of chronology and tectonic setting in study area,we discuss the origin and evolution of Zedang ophiolite.①Based on a resrarch of Fo values of olivine,En and Mg# values of clinopyroxene and orthopyroxene,contents of Al2 O3 of clinopyroxene and orthopyroxene,Mg# and Cr# values of spinel,we found that Zedang mantle peridotites originated from depleted mantle source in a MOR(mid-ocean ridge) environment,then was modified by later-stage melts and fluids in a SSZ (Suprasubduction Zone)setting, and that the molten degree of harzburgites is higher than lherzolites.② Based on a resrarch of petrochemistry and geochemistry of mantle peridotitses,we found the contents of most major elements and trace elements in mantle peridotites are lower than that in primitive mantle,the distribution patterns of trace-elements well coincide with abyssal peridotites,which proved again mantle peridotitses originated from depleted mantle source in a MOR environment.③We found that gabbros from Zedang ophiolite had the feature of N-MORB (Normal type Mid-Ocean Ridge Basalts)and originated from a source region which was much more depleted than N-MORB,the gabbros also had the feature of IAT(Island Arc Tholeiites) and probably ascribe it modified in a SSZ setting.④There are two types basalts in Zedang ophiolite, N-MORB and E-MORB(Enriched type Mid-Ocean Ridge Basalts),because the source region might have the feature of inhomogeneity,which include enriched magma.N-MORB type basalts also have the feature of IAT,indicating them modified in a SSZ setting later,whereas E-MORB type basalts not have the feature of IAT.⑤Combined with previous research of chronology and tectonic setting in study area, Zedang ophiolite originated from depleted and inhomogeneous mantle source in a MOR environment in c. 170Ma,then was modified in a fore-arc setting in c.150 Ma.关键词
泽当蛇绿岩/雅鲁藏布江缝合带/MOR/SSZKey words
Zedang ophiolite/Yarlung Zangbo Suture Zone/MOR/SSZ引用本文复制引用
李强,夏斌,黄强太,夏连泽,夏中宇..雅鲁藏布江蛇绿岩带东段泽当蛇绿岩起源及演化[J].地质学报,2014,(2):145-166,22.基金项目
本文为国家“973”项目（编号2012420004108011）和广东省普通高校海洋石油勘探开发重点实验室（编号2010420004201001）共同资助成果。 （）
