Adakitic lavas in the Central Luzon back‐arc region, Philippines: lower crust partial melting products?
Adakitic lavas in the Central Luzon back‐arc region, Philippines: lower crust partial melting products?
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DOI：
10.1111/j.1440-1738.2000.00297.x
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发表时间：
2000-12
期刊：
影响因子：
1.5
通讯作者：
G. Yumul;C. Dimalanta;H. Bellon;D. Faustino;J. De Jesus;Rodolfo A. Tamayo;Ferdinand T. Jumawan
中科院分区：
文献类型：
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作者：
G. Yumul;C. Dimalanta;H. Bellon;D. Faustino;J. De Jesus;Rodolfo A. Tamayo;Ferdinand T. Jumawan
摘要菲律宾吕宋岛中部弧后侧地区的火山活动，相对于马尼拉海沟，其特征是与相邻的弧前侧主火山弧火成岩相比，火山中心数量较少且体积较小。弧后火山岩包括玄武岩、玄武安山岩、安山岩和英安岩，也含有更多的含水矿物（即角闪石和黑云母）。这些弧后熔岩的埃达克岩样地球化学特征，包括高Sr，亏损重稀土元素和高Sr/Y比值，不太可能是由板片熔融形成的，与初始俯冲，板片窗口岩浆作用或斜长石堆积有关。野外和地球化学证据表明，这些埃达克质熔岩很可能是由含石榴子石的角闪岩下地壳部分熔融形成的。埃达克质熔岩不一定是弧沟间隙区板片熔体。
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.