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大降坪黄铁矿矿床 3号、 4号矿体和硅质物的铅同位素指示 ,铅来源于基底混合岩和矿体围岩细碎屑岩的混合 ,灰岩的铅同位素反映是细碎屑岩或基底混合岩和震旦纪海水的混合铅。矿石和围岩 2 0 7Pb/ 2 0 4Pb比值高 ,具有古老基底铅同位素组成特征。钕模式年龄与 2 0 7Pb/ 2 0 4Pb显示出较好的正相关关系 ,说明具放射成因越高 ,铅来源于越老的地壳。块状矿石和硅质物的εNd (0 ) =- 13.9～ - 16 .5 ,钕模式年龄 t DM为 1340× 10 6～ 2 85 9× 10 6a,反映其物源为古老的前震旦纪基底物质。 Sm - Nd等时线年龄为 (2 30± 13)× 10 6a,或许反映了粤西地区古特提斯构造运动的热动力事件年龄
Pb isotopes of ore bodies No.3 and No.4 of the Dajianping pyrite deposit and siliceous materials indicate that Pb is derived from the mixing of basal-migmatite and ore-bearing fine-grained rocks, and the lead isotope of limestone is finely crushed Lead mixed rock or basement mixed rock and Sinian seawater. Ore and surrounding rocks have a high ratio of 207Pb / 204Pb and have the characteristics of ancient basement Pb isotopic composition. Neodymium model age and 207Pb / 204Pb showed a good positive correlation, indicating that the higher the cause of radiation, lead from the older crust. The εNd (0) = - 13.9 ~ - 16.5 for massive ores and siliceous rocks and the neodymium model ages of 1340 × 10 6 ~ 2 85 9 × 10 6 a indicate the provenance of the ancient fore-Sinian basement substance. The Sm-Nd isochron age is (2 30 ± 13) × 10 6 a, which may reflect the thermodynamic event age of the tectonic movement of the ancient Tethys in western Guangdong