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Adakitic lavas in the Central Luzon back‐arc region, Philippines: lower crust partial melting products?
Author(s) -
Yumul Graciano P.,
Dimalanta Carla,
Bellon Herve,
Faustino Decibel V.,
De Jesus Joel V.,
Tamayo Rodolfo A.,
Jumawan Ferdinand T.
Publication year - 2000
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.2000.00297.x
Subject(s) - adakite , geology , andesites , geochemistry , partial melting , forearc , volcanic arc , crust , island arc , magmatism , petrology , basalt , subduction , igneous rock , plagioclase , volcanic rock , oceanic crust , volcano , andesite , seismology , quartz , tectonics , paleontology
Volcanism in the back‐arc side region of Central Luzon, Philippines, with respect to the Manila Trench is characterized by fewer and smaller volume volcanic centers compared to the adjacent forearc side‐main volcanic arc igneous rocks. The back‐arc side volcanic rocks which include basalts, basaltic andesites, andesites and dacites also contain more hydrous minerals (ie, hornblende and biotite). Adakite‐like geochemical characteristics of these back‐arc lavas, including elevated Sr, depleted heavy rare earth elements and high Sr/Y ratios, are unlikely to have formed by slab melting, be related to incipient subduction, slab window magmatism or plagioclase accumulation. Field and geochemical evidence show that these adakitic lavas were most probably formed by the partial melting of a garnet‐bearing amphibolitic lower crust. Adakitic lavas are not necessarily arc–trench gap region slab melts.