WORLDWIDE OCCURRENCE OF SILICA-RICH MELTS IN SUB-CONTINENTAL AND SUB-OCEANIC MANTLE MINERALS

被引:207
作者
SCHIANO, P [1 ]
CLOCCHIATTI, R [1 ]
机构
[1] CENS,LAB PIERRE SUE,SCI TERRE GRP,F-91191 GIF SUR YVETTE,FRANCE
关键词
D O I
10.1038/368621a0
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
ROCK samples derived from the Earth's upper mantle commonly show indirect evidence for chemical modification. Such modification, or 'metasomatism', can be recognized by the precipitation of exotic minerals such as phlogopite, amphibole or apatite1, and by the overprinting of the bulk compositions of the mantle rocks by a chemical signature involving the enrichment of potassium and other 'incompatible' elements2. Here we study the composition of the metasomatic agents more directly by examining melt and fluid inclusions trapped in mantle minerals. These inclusions are secondary, forming trails along healed fracture planes. A systematic study of the chemical compositions and entrapment temperatures and pressures of inclusions from 14 ultramafic peridotites from both continental and oceanic intraplate regions shows that volatile- and silica-rich metasomatic melts are present throughout the lithosphere. Their compositions, which differ dramatically from those of erupted, mantle-derived magmas, are more akin to continental than to oceanic crust.
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页码:621 / 624
页数:4
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