Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

M. Grégoire (1) , Sébastien Jégo (2) , René Maury (3) , Betchaida D. Payot (4) , Rodolfo A. Tamayo (4) , Graciano P. Yumul (5)

1 DTP - Dynamique terrestre et planétaire
2 ISTO - Institut des Sciences de la Terre d'Orléans
3 LDO - Domaines Océaniques
4 Philippine Council for Industry and Energy Research and Development-DOST
5 NIGS UP - National Institute of Geological Sciences [Philippines Univ]

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.

Mots clés: mantle xenoliths; Luzon arc; metasomatism; dunite; trace elements; adakite

Domaines: Volcanologie; Milieux et Changements globaux

M. Grégoire, Sébastien Jégo, René Maury, Betchaida D. Payot, Rodolfo A. Tamayo, et al.. Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines). Lithos, 2008, 103 (3-4), pp.415-430. ⟨10.1016/j.lithos.2007.10.013⟩. ⟨insu-00256478⟩