Geology, Geochemistry and Chromite Mineralization Potential of the Amnay Ophiolitic Complex, Mindoro, Philippines

作者：Yumul Graciano P Jr^*; Jumawan Ferdinand T; Dimalanta Carla B

来源：Resource Geology, 2009, 59(3): 263-281.

DOI：10.1111/j.1751-3928.2009.00095.x

• Amnay
• back-arc basin
• chromitite
• fertile mantle
• Mindoro
• ophiolite
• Philippines
• South China Sea

The Amnay Ophiolitic Complex in Mindoro, the Philippines, is considered an emplaced Cenozoic South China Sea oceanic lithosphere as a result of the collision between the Palawan microcontinental block and the Philippine mobile belt. Middle Oligocene sedimentary rocks intercalated with dominantly MORB-like pillow lavas and volcanic flows suggest the generation of this ophiolite complex in an intermediate spreading ridge within a back-arc basin setting. The volcanic rock suite geochemistry also manifests a slab component suggesting that it is a supra-subduction zone ophiolite. Petrography of the gabbros shows a plagioclase-clinopyroxene crystallization order consistent with a back-arc basin setting. Spinel and pyroxene geochemistry shows that the lherzolites and aluminous-spinel harzburgites are products of low degrees of partial melting. The chromitites hosted by the harzburgites could have not been associated with the MORB-like volcanic suites, gabbros, lherzolites and aluminous-spinel harzburgites. The chromitites are products of mantle sources that have undergone higher degrees of partial melting that would have involved the presence of water. The study of this ophiolitic complex gives us a glimpse of the characteristics of the South China Sea.

• 出版日期2009