Behavior of Platinum-Group Elements during Mantle Metasomatism by Asthenospheric Melt

• 责任者：Wang Jian (College of Earth Sciences ; Jilin University ; Changchun 130061 ; China) ; Keiko H. Hattori
• 刊名：Earth Science Frontiers
• 出版年：2010
• 卷期：17（1)
• 关键词：铂族元素矿床 ; platinum-group elements deposit ; 交代作用 ; metasomatism
• 页码：p.164-176
• 图表：5 illus., 1 table, 57 refs.
• 分类号：1001
• issnNo：ISSN1005-2321
• isbnNo：CN11-3370/P

Garnet-bearing orthopyroxenites occurred as both discrete xenoliths and veinlets in peridotite xenoliths that were brought to the surface by Quaternary Pali Aike alkali basalts in southern South America. Or- thopyroxenites commonly contain Ti-rich minerals and also relict grains of olivine and clinopyroxene occurring as inclusions in secondary orthopyroxene.  The secondary orthopyroxene contains high TiO₂, moderate Al₂O₃ and low Mg# compared with orthopyroxene in garnet-bearing peridotites. It suggests that the secondary orthopyroxene formed at the expense of olivine and clinopyroxene during the metasomatism by an evolved Ti-rich melt. Compared with peridotites, the orthopyroxenites contain slightly low Co and Ni, and similar Cr and PGE, suggesting that these metals were essentially immobile during metasomatism.