Petrogenesis of massif-type anorthosite complex, Gruber, Central Dronning Maud Land, East Antarctica: Implications for magma source and evolution |
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作者单位: | [1]National Oceanography Centre, European Way, Southampton, S014 3ZH, United Kingdom [2]Geological Survey of India, Faridabad, NH31, Haryana, India [3]National CentreforAntarctic & Ocean Research, Goa-403804, India |
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摘 要: |
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关 键 词: | 东南极洲 斜长岩 岩浆源 块型 成因 中央 演变 |
收稿时间: | 14 January 2005 |
Petrogenesis of massif-type anorthosite complex,Gruber, Central Dronning Maud Land,East Antarctica: Implications for magma source and evolution |
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Authors: | Anju Pandey Amit Dharwadkar Rasik Ravindra Andy Milton |
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Institution: | 1.National Oceanography Centre,Southampton,UK;2.Geological Survey of India,Faridabad,India;3.National Centre for Antarctic & Ocean Research,Goa,India |
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Abstract: | The origin of anorthosite and associated igneous gabbronorite and ferrodiorite was investigated through detailed study of
a typical massif-type anorthosite complex from Gruber, Central Dronning Maud Land, East Antarctica. Field observations showed
that the Gruber Complex is made up of gabbronorite-anorthosite pluton which was intruded by ferrodiorite dykes. Systematic
samples collected from the Gruber Complex revealed significant geochemical variations within the region. Four rock types have
been identified, based on modal proportions of mineral phases and their geochemistry data. Clinopyroxene-gabbronorite and
plagioclase-gabbronorite are the two types of gabbronorite with the dominance of clinopyroxene and plagioclase, respectively.
Anorthosite is represented by rocks having predominance of plagioclase with minor clinopyroxene. Ferrodiorite is characterized
by modal abundance of orthopyroxene and Fe-Ti oxide. Major and trace element systematics showed that all the four rock types
are co-magmatic and are related through fractional crystallization. Based on this study, it is reported that clinopyroxene
was the first phase to crystallize followed by plagioclase and then Fe-Ti oxides. Furthermore, trace element composition of
the parental melt was calculated using LA-ICPMS analysis of the most primitive, pure clinopyroxene found in the clinopyroxene
gabbronorite. Our analyses suggested that the parental melt was similar to that of continental arc basalt and showed signatures
of subduction-related metasomatism. Based on mineral chemical and geochemical data, it is interpreted that the parent melt
went through changing sequence of crystallization which led to the formation of massive anorthosite. |
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Keywords: | massif-type anorthosite Gruber East Antarctica LA-ICPMS geochemistry |
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