Adakitic lavas in the Central Luzon back-arc region, Philippines: lower crust partial melting products?
Article first published online: 18 JUL 2008
© 2000 Blackwell Science Asia Pty Ltd.
Volume 9, Issue 4, pages 499–512, December 2000
How to Cite
Yumul, G. P., Dimalanta, C., Bellon, H., Faustino, D. V., De Jesus, J. V., Tamayo, R. A. and Jumawan, F. T. (2000), Adakitic lavas in the Central Luzon back-arc region, Philippines: lower crust partial melting products?. Island Arc, 9: 499–512. doi: 10.1111/j.1440-1738.2000.00297.x
- Issue published online: 18 JUL 2008
- Article first published online: 18 JUL 2008
- adakitic lavas;
- island arc;
- lower crust;
- partial melting;
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.