Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)
- 作者：M. Gregoire ; S. Jego ; R.C. Maury ; M. Polve ; B. Payot ; R.A. Tamayo Jr. ; G.P. Yumul Jr.
- 关键词：Mantle xenoliths ; Luzon arc ; Metasomatism ; Dunite ; Trace elements ; Adakite
- 刊名：Lithos
- 出版年：2008
- 期刊代码：54_00244937
- 类别：ear
- 出版时间：July 2008
- 卷：103
- 期：3-4
- 页码：415-430
- 文件大小：2108 K
摘要
The Monglo adakite contains mafic and ultramafic xenoliths, which probably originated from the mantle section of an Early Cretaceous supra-subduction zone ophiolitic complex located within the Luzon arc crust. Spinel-bearing dunites are dominant among this xenolith collection and display evidence for three episodes of subduction-related melt percolation. The first one is evidenced by an undeformed clinopyroxene characterized by convex-upwards REE pattern. This clinopyroxene crystallized from a calc-alkaline basaltic magma, likely formed in the Cretaceous supra-subduction setting of the ophiolite. Then, two metasomatic events, evidenced by orthopyroxene-rich and amphibole-rich secondary parageneses, respectively, affected most of the spinel dunites. The opx-rich paragenesis is related to the circulation within the dunitic upper mantle of hydrous slab-derived melts similar to those affecting the mantle peridotite xenoliths from Papua New Guinea and Kamchatka. Finally the amphibole-rich veins are related to the interaction between the studied dunite xenoliths and the host adakite or an adakitic melt similar to it.