Abstract

Song Hinh area belongs to the southeastern edge of Kon Tum Block on the Buon Ma Thuot geological map sheet (D-49-XV) at a scale of 1:200. The methods of analyzing major elements, trace elements and Sr-Nd isotopes show these Granitoids consist mainly of porphyritic biotite granite, biotite-horblende granodiorite, located in the peraluminous field and belonging to both I-granite type, cal-alkaline to high-potassium cal-alkaline series. Light rare earth elements (LREE) are richer than heavy rare earths (HREE), the ratios of light rare earths to heavy rare earths are: (La/Sm)N: 4.90-8.36 times and average: 6.63 times; (La/Yb)N: 29.82-64.12 times and average: 46.97 times; (Gd/Yb)N: 2.59-8.57 times and TB: 5.58 times. The negative Eu anomaly in the molten mass shows that during the rock formation process, due to fractional crystallization or partial melting, feldspar was retained in the source. The ratio: Eu/Eu* = 1.17-1.24 times and TB: 1.20 times. The above rare earth element behavior characteristics show that granitoids are close to high potassium cal-alkalis. The granitoids crystallized at temperatures from about 680 to 7100C (except for the vein rocks with temperatures of 730-750oC) under conditions where the water vapor pressure was mainly less than 1 kbar. Isotopic results eNd = -7.9796 and -8.7117, 87Sr/86Sr = 0.711 and 0.711 show that the Granitoid is in a mixed mantle field. The magma source zone of Song Hinh block granitoid gives the formation age values ​​of 1.77 and 1.93 billion years. The granitoid magmas have source temperature values ​​ranging from 1113 to 1291°C and source pressure from 8.5 to 9.8 Kbar. The granitoid has a similar tectonic context of VAG volcanic arc and continental collision (Syn - COLG), belonging to the active continental margin according to classification. According to classification, they belong to oceanic arc granite CAG and continental collision granite CCG. They are proven to have a mixed mantle origin due to partial melting of mantle differentiation with crustal material, with the melting mechanism: subduction zone energy: exchange and dissolution of solution from shear zone to overburden; overburden melting; heat flow from deep up.