Geochemistry and petrology of the volcanic rocks from the Sulu Sea@en

Major-, trace-, and rare-earth element analyses of the basaltic rocks recovered from the basement of the Sulu Sea and of lithic clasts from the pyroclastic unit representing the acoustic basement of the Cagayan Ridge, are presented. The major and trace elements were measured by X-ray fluorescence techniques, and rare-earth elements by instrumental neutron activation analysis. These data show that the Sulu Sea basalts are back-arc tholeiites and the lithic clasts are basalts, basaltic andesites, and andesites typical of volcanic arc suites erupted on continental crust. Petrogenetic modeling is used to show that the Sulu Sea basalts were derived from a heterogeneous mantle, probably representing subcontinental lithosphere, with contributions from a subduction component. The Sulu Sea is interpreted as a back-arc basin formed by rifting of an Oligocene to early Miocene volcanic arc leaving the Cagayan Ridge as a remnant arc. This event occurred during northward subduction of the Celebes Sea basement beneath the Oligocene to early Miocene arc.本数据集收录了采自苏禄海（Sulu Sea）基底的玄武岩，以及代表卡加延海岭声学基底的火山碎屑岩单元中的岩屑碎屑的主量、微量与稀土元素分析数据。其中主量元素与微量元素采用X射线荧光（X-ray fluorescence）技术测定，稀土元素则通过仪器中子活化分析（instrumental neutron activation analysis）完成检测。分析数据表明，苏禄海玄武岩属于弧后拉斑玄武岩，而上述岩屑碎屑为发育于大陆地壳之上的典型火山弧岩套成员，包括玄武岩、玄武安山岩与安山岩。通过岩石成因模拟研究可知，苏禄海玄武岩源自不均一地幔，该地幔大概率代表大陆下岩石圈，且受到俯冲组分的物质贡献。研究认定苏禄海为弧后盆地，其形成源于渐新世至早中新世火山弧的裂离作用，卡加延海岭便是该构造事件遗留的残余弧，这一过程发生于西里伯斯海（Celebes Sea）基底在渐新世至早中新世火山弧下方向北俯冲的时期。