Adakitic lavas in the Central Luzon back-arc region, Philippines: lower crust partial melting products?

Authors

  • Graciano P. Yumul JR,

    Corresponding author
    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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  • 1 Carla Dimalanta,

    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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  • 1 Herve Bellon,

    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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  • 2 Decibel V. Faustino,

    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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  • 1 Joel V. De Jesus,

    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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  • 1 Rodolfo A. Tamayo JR,

    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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  • and 1,2 Ferdinand T. Jumawan 1

    1. 1 Rushurgent Working Group, National Institute of Geological Sciences, College of Science, University of the Philippines, Diliman, Quezon City, The Philippines, (email: rwg@i-next.net), 2UMR 6538 Domaines Oceaniques, Universite de Bretagne Occidentale 6, Avenue le Gorgeu—BP 809, F-29285 Brest Cedex, France
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*Correspondence

Abstract

Abstract 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.

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