Petrography and Geochemistry of Peridotite Xenoliths from Hannuoba and Significance for Lithospheric Mantle Evolution  

作　　者：余淳梅 郑建平 Griffin WL 

机构地区：[1]Facultyof Earth Sciences , China University of Geosciences , Wuhan430074, China [2]Facultyof Earth Sciences , China University of Geosciences , Wuhan430074, China, State KeyLaboratoryof Geological Processes and Mineral Resources , China University of Geosciences, Wuhan430074, China [3]GEMOC, Department of Earth and Planetary Sciences , Macquarie University, Sydney, NSW2109, Australia

出　　处：《Journal of China University of Geosciences》2006年第1期25-33,共9页中国地质大学学报（英文版）

基　　金：This paper is supported by the Research Foundation for OutstandingYoung Teachers , China University of Geosciences ( Wuhan )(CUGQNL0510);the National Natural Science Foundation of China(No .40425002) .

摘　　要：The compositions of the whole rocks and trace elements of minerals in peridotites can reflect the characteristics of the lithospheric mantle. The nature and evolution of the Cenozoic lithospheric mantle beneath Hannuoba （汉诺坝）, located on the north edge of the intra-North China orogenic belt, are discussed based on the in-situ LAM-ICPMS detected trace element compositions of clinopyroxenes in the Hannuoba peridotitic xenoliths combined with detailed petrography and geochemistry studies. The Hannuoba lithospheric mantle was formed by different partial meltings of the primitive mantle. Most of the samples reflect the partial melting degree of lower than 5% with a few samples of 15%-20%. Major element compositions of the whole rocks and geochemical compositions of clinopyroxenes reveal the coexistence of both fertile and depleted mantle underneath the Hannuoba region during the Cenozoic. This was probably caused by the asthenospheric mantle replacing the aged craton mantle through erosion, intermingling and modification. Our conclusion is further supported by the existence of both carbonatitic magmatic material and silicate melt/ fluid metasomatism as magnified by the trace elements of the clinopyroxencs from the Hannuoba lithospherJc mantle.The compositions of the whole rocks and trace elements of minerals in peridotites can reflect the characteristics of the lithospheric mantle. The nature and evolution of the Cenozoic lithospheric mantle beneath Hannuoba （汉诺坝）, located on the north edge of the intra-North China orogenic belt, are discussed based on the in-situ LAM-ICPMS detected trace element compositions of clinopyroxenes in the Hannuoba peridotitic xenoliths combined with detailed petrography and geochemistry studies. The Hannuoba lithospheric mantle was formed by different partial meltings of the primitive mantle. Most of the samples reflect the partial melting degree of lower than 5% with a few samples of 15%-20%. Major element compositions of the whole rocks and geochemical compositions of clinopyroxenes reveal the coexistence of both fertile and depleted mantle underneath the Hannuoba region during the Cenozoic. This was probably caused by the asthenospheric mantle replacing the aged craton mantle through erosion, intermingling and modification. Our conclusion is further supported by the existence of both carbonatitic magmatic material and silicate melt/ fluid metasomatism as magnified by the trace elements of the clinopyroxencs from the Hannuoba lithospherJc mantle.

关 键 词：peridotite xenoliths LAM-ICPMS lithospheric mantle evolution HANNUOBA North China craton 

分 类 号：P588.1[天文地球—岩石学]