Stanniferrous Granites of Vietnam: Rb-Sr and Ar-Ar Isotope Age, Composition, Sources, and Geodynamic Formation Conditions

摘要

Stanniferrous granite-leucogranite massifs in Vietnam to which the bedrock and placer commercial deposits of cassiterite are associated (Timtuc etc.) are of late Cretaceous age (～85 Ma by Rb-Srand Ar-Ar isotope dating). These massifs are presented by stocks and fracture intrusions (to 100 km~2 in area) of simple homodromic structure: biotite granites => two-mica and muscovite leucogranites => topaz-containing aplites => rare-metal pegmatites.