Publication Date:
2018-03-09
Description:
The continental margin of Southeast Asia evolved from a dominantly Andean - type active margin during Mesozoic to a Western Pacific - type since Late Cretaceous. With the spreading of the South China Sea, the Palawan - Mindoro Block drifted from mainland Asia and the Cenozoic strata provide an excellent window to gain insights into the tectonic evolution of the margin of Southeast Asia. Here we present U - Pb age and Hf isotopic data on detrital zircon grains from Cenozoic sedimentary rocks in the Palawan - Mindoro Block, the Philippines to evaluate the provenance and tectonic evolution of the South China Sea. Zircon grains in Eocene - Miocene sedimentary rocks from the Palawan - Mindoro Block show a wide range in age from 60 to 2700 Ma, with four major age groups of 80 - 120 Ma, 160 - 180 Ma, 1600 - 2100 Ma and 2200 - 2700 Ma. The εHf(t) of the zircon grains of the samples from Mindoro Island range from −39 to +13.7 and similar Hf isotopic composition is recorded in Paleogene and Neogene strata. Zircon U - Pb ages and Hf isotopic data of the Eocene samples from the Palawan - Mindoro Block show a similar pattern with those from Taiwan, which suggests that the Palawan - Mindoro Block was attached to the margin of South China during Late Cretaceous - Eocene times. The difference of zircon U - Pb age composition in the Miocene samples between the Palawan - Mindoro Block and Taiwan reflects southward drifting of the Palawan - Mindoro Block and seafloor spreading of the South China Sea at that time.
Print ISSN:
0278-7407
Electronic ISSN:
1944-9194
Topics:
Geosciences
