GRANITOID PETROLOGY OF HAI VAN MASSIF

Abstract

The granitoid formations of Hai Van massif with petrographical components consist of  biotite granite, two mica granite. Chemical components of  rocks are: SiO₂: 69,34÷73,92%, Na₂O+K₂O:  6,11÷8,11%, K₂O/Na₂O>1. Content of Ba, Sr is low but Rb is higher. From results of  Nd–Sm isotopic analysic shows that they are nearly same with stable crust material. Age of  source region formation is 1,33 billion  years  (model of  homogeneous chondrite source region), or 1,95 billion  years  (model of  poor mantle source  region). U–Pb isotopic age: 241,9± 2 and 241,4±2.1 million years.