U and Th Sources and Enrichment Mechanisms of High Heat Producing Granites in Xingluokeng,Fujian Province
Hu Fanfen
Liu Hao
Wang Yong
Liu Xiangchong
Abstract：Tungsten deposit is genetically related to highly differentiated granites.The radioactive heat production of those tungsten-associated granites is mostly 5-10 μW·m-3 and can be classified into high heat-producing granites.The radioactive heat mainly comes from U(70％),followed by Th(20％)and K(＜10％).The distribution pattern and genesis of heat-producing elements in tungsten granites are still unclear.The Xingluokeng large-scale tungsten deposit in Fujian Province was chosen as a typical case study.The main occurrence minerals of U,Th,and K were constrained using the principle of mass conservation,the compositional analysis of single minerals(biotite,plagioclase,zircon,monazite,and apatite),and published major and trace element data of the whole rock in the Xingluokeng granites.The zircon U-Pb ages of G1 and G2 are 151.5±0.6 Ma and 150.0±0.6 Ma,respectively.The total heat production rates of G1 and G2 calculated from single minerals are 1.78 μW·m-3 and 2.28 μW·m-3,respectively.Among them,K mainly occurs in K-feldspar and biotite,and the heat contribution rate of K of these two minerals to the whole rock is less than 10％.Th mainly comes from monazite,and the Th heat contribution rate in monazite is 46％at the highest.U mainly comes from zircon and monazite,and the heat contribution rate is less than 15％.The heat production rates of G1 and G2 minerals are 48％and 37％of the whole rock average heat production rates(3.74 μW·m-3 and 6.10 μW·m-3,respectively).This significant difference may be due to a large amount of U existing in a small amount of high-U zircon.Due to the limited statistical sampling of these high-U zircons,the calculated heat production rate from single minerals tends to be underestimated.The enrichment of U and Th in the Xingluokeng granites may be controlled by the protoliths and later crystallization differentiation.The decay heat from radioactive elements in the Xingluokeng granite(especially the late granite)may prolong the time limit of hydrothermal convection and promote the formation of scheelite.
Keywords：heat-producing elementszirconmonazitetungsten depositXingluokengmineral deposits
Publication Date：2025-04-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：21( 1380-1400 )