The Petrological and Geochemical Features of Basalts from Dredging Stations 2776 and 2764 (Philippine Sea)

摘要

This paper reports original geochronological and trace-element data on basalts from the dredging sites 2776 and 2764 located in the southern part of the Central Fault in the Philippine Sea. The studies showed that the basalts from st. 2776 demonstrate chemical features of mid-ocean ridge and ocean island-arc basalts (N-MORB+OIAB), while basalts from st. 2764 show E-MORB+OIAB signatures. A comparative analysis of chemical composition of the volcanic rocks from both stations and Kyushu–Palau Ridge indicates that most of the rocks were derived from melts enriched in “subduction” and within-plate (WPB) components. However, WPB signatures occur in the rocks more frequently at the primitive mantle (PM) level and did not reach those of ocean-island alkaline basalts (OIB).