Imprints of Late Mesozoic tectono-magmatic events on Palawan Continental Block in northern Palawan, Philippines

Abstract

A recent investigation in Palawan Island led to the recognition of the Daroctan Granite, a pluton that intruded the Mesozoic mélange in the northernmost part. The occurrence and age of the magmatism is presented in this study as well as the maximum age of deposition for some Late Mesozoic lithostratigraphic units. Geochronological studies on zircon and monazite was carried out to unravel the Late Mesozoic tectonic evolution of this area. Monazite U-Th-total Pb dating was used to determine the age of the Daroctan Granite, which yielded a Late Cretaceous age similar to some of the Mesozoic granites surrounding the South China Sea. Zircon U-Pb and monazite U-Th-total Pb dating were also used to determine the maximum age of deposition of the sedimentary units belonging to the Guinlo Formation and Tumarbong Semi-schist. The results show a Jurassic to Early Cretaceous age range with a Late Cretaceous maximum age of deposition for the meta-sedimentary units. This sliver of the Palawan Continental Block, which is composed of accreted units, might have been located at the margin of the continent-ocean collision during the Mesozoic wherein detrital minerals with mostly Late Cretaceous ages were deposited. It was later intruded by the Daroctan Granite and eventually broke off from the southeastern Eurasian margin. These findings provide additional constraints on the tectonic evolution of the Palawan Continental Block.