Geochemical Characteristics and Geological Significance of Dapaitian rock mass in the Lanhe Area, North Guangdong

The Dapaitian rock mass is located in the Lanhe uranium mineralization concentratedSarea. Its detailed petrographic and geochemical features were analyzed to understand its petrogenesis, characteristics of magma source area, and the relationship with uranium mineralization. The results show that the coarse-grained porphyritic biotite granite has high SiO₂ (73.6%～76.5%), rich Al₂O₃ (12.4%～13.5%), and rich alkali (K₂O=5.21%～5.63%, Na₂O=2.44%~2.76%), K is greater than Na, poor in MgO (0.23%~0.52%), the aluminum saturation index (A/CNK) is 1.30~1.56, FeOt/MgO is 3.21~6.61, indicative of high potassium calcium-alkaline peraluminous granite. In the trace elements composition, Rb, Th, U, and Ta are relatively enriched, and the elements such as Ba, Nb and Sr are relatively depleted. In the rare earth elements, The distribution pattern of rare earth elements is right-leaning, with obvious fractionation of light and heavy rare earths. Light rare earths are relatively enriched (112×10^_-6~245×10^_-6), and heavy rare earths are relatively depleted (26.7×10^_-6~53.3×10^_-6), Eu is negative anomaly. The above geochemical characteristics indicate that Dapaitian rock mass is characteristics of A2-type granite. it May be formed under the background of extensional structure, partial melting of meta-shale sedimentary rocks.