Mantle Evolution from Ocean to Arc: The Record in Spinel Peridotite Xenoliths in Mt. Pinatubo, Philippines

Minerals

Akihiro Tamura¹  Shoji Arai¹  Mitsuru Okuno²  Masako Yoshikawa³  BetchaidaD. Payot⁴  DanikkoJohn V. Rivera⁵ 

[1] Department of Earth Sciences, Kanazawa University, Kakuma, Kanazawa 920-1192, Japan;Department of Earth System Science, Fukuoka University, Fukuoka 814-0180, Japan;Department of Earth and Planetary Systems Science, Hiroshima University, Hiroshima 739-8526, Japan;National Institute of Geological Sciences, University of the Philippines, Diliman, Quezon City 1101, Philippines;Philippine Institute of Volcanology and Seismology, Diliman, Quezon City 1101, Philippines;

关键词: xenoliths;    Mt. Pinatubo;    Philippines;    mantle wedge;    abyssal lherzolite;    arc harzburgite;   

DOI  :  10.3390/min8110515

来源: DOAJ

【 摘 要 】

A suite of peridotite xenoliths were collected from lahar flow deposits located close to the summit of Mt. Pinatubo. Spinel harzburgite is the most dominant lithology among dunites, pyroxenites and websterites. A rare spinel lherzolite xenolith (P12-7) is also present in this suite. The spinel lherzolite has well-preserved protogranular texture with very minimal presence of secondary amphibole, low Cr# in the chromian spinel, and depleted and hump shaped patterns of chondrite-normalized rare earth element (REE) patterns for the clinopyroxenes. In contrast, the spinel harzburgites contain abundant secondary amphiboles and orthopyroxenes, higher Cr# in the spinel, and slightly elevated patterns for the chondrite-normalized REE patterns for the amphiboles. The spinel lherzolite also exhibits higher olivine Fo content for a given spinel Cr# compared to the spinel harzburgites. The spinel lherzolite is interpreted as a typical residue from partial melting of abyssal peridotites whereas the spinel harzburgites may have formed via partial melting with subsequent modification during the influx of fluids in the mantle wedge. Our results suggest that fragments of MOR-derived lithosphere exist in the mantle wedge beneath the Philippine island arc. This work provides evidence for the conversion of abyssal to arc peridotites in the mantle wedge.

【 授权许可】

Unknown