South China continental margin signature for sandstones and granites from Palawan, Philippines

Abstract

We report results of heavy mineral analysis and U-Pb dating of detrital zircons from metasediments and Cenozoic sandstones, and U-Pb dating of zircons from Cenozoic granites of the North Palawan Continental Terrane (NPCT) and the South Palawan Terrane (SPT). The NPCT metasediments are derived mainly from granitic and metamorphic rocks of continental character. They contain zircons that indicate a maximum depositional age of Late Cretaceous and other age populations indicating a South China origin. The sediments were deposited on the South China margin before rifting of the continental margin during opening of the South China Sea. Miocene SPT sandstones contain similar heavy mineral assemblages suggesting sources that included NPCT metasediments, metamorphic basement rocks at the contact between the SPT and the NPCT, South China Sea rift volcanic and/or minor intrusive rocks, and the Palawan ophiolite complex. The SPT sandstones are very similar to Lower Miocene Kudat Formation sandstones of northern Borneo suggesting a short-lived episode of sediment transport from Palawan to Borneo in the Early Miocene following arc-continent collision. U-Pb dating of zircons shows that the Central Palawan granite is Eocene (42. ±. 0.5. Ma). The Capoas granite was intruded during a single pulse, or as two separate pulses, between 13.8. ±. 0.2. Ma and 13.5. ±. 0.2. Ma. Inherited zircon ages from the Capoas granite imply melting of continental crust derived from the South China margin with a contribution from Cenozoic rift-related and arc material. Show more