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+KO: 6,11-8,11%, K2O/Na20>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.
Ba Na granitoid is isometric shape, with exposure of 30 sqa km area. Petrographic composition is mainly coarse - medium grained biotite granite, included in the first phase. The fine grained leuco rock of the second phase is small massif in shape, distributed along fault in NE-SW direction. SiO, content of Bana granitoid is variation from 73.74% to 76.24%. Total of K2O +Na2O is from 7.32% to 8.33%. Ratio of K2O/Na2O: 1.66 - 2.07. This is S-Granite. Value of 147Sm/144Nd = 0,1249 is nearly stable crust material. Ratio of Sm/Nd is low. ena has negative value and very small proved that Ba Na granitoid must derive from crust source or mantle source which rich (EM). The age of source regional forming calculated from isotopic of Sm, Nd is 1.06 Ba (according to model of chondrite mantle source region) or 1.74 Ba (according to model of poor mantle source). The prospects of related mineralization of Ba Na granitoid is Sn (W, Nb, Ta) with amsemblage of topaz - cassiterite - tourmaline - quartz (sometime is Ta - Nb). The result of isotopic analysis of U Pb in zircon of Ba Na biotite granite sample at lab of Tasmania University, Australia, age of Ba Na is 242.9 +1.5 Ma and 240.6 2.2 Ma.
Temperature, Pressure, and Composition of the Mantle Source Region of Late Cenozoic Basalts in Hainan Island, SE Asia: a Consequence of a Young Thermal Mantle Plume close to Subduction Zones?