U-Pb zircon LA-ICP-MS and Hf composition in andesite of Ru Ri pass - Nha Trang and its geological significance

Abstract

Zircons separated from an andesite sample in the Nha Trang formation, in the Khanh Hoa province were dated to determine the protolith age for the complex. Thirty LA-ICP-MS U-Pb zircon analyses gave concordant ages concentrated at 100.9±1.7 Ma, corresponding to the late cretaceous period. These results indicated the protolith age of the ryolite (primary magma crystallization age). The εhf(t) component values ranged from (-)0.6 to (+)10.7, mainly for positive value and only one negative value (-)0.6. It showed that the source of the material forming the andesite eruptions was mainly from mantle, and the continental crust material took part in the formation of the involvement.