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针对佛子冲地区产出的正长花岗岩进行锆石LA-ICP-MS锆石U-Pb同位素年代学研究,结果表明,该岩体的形成年龄为170.8 Ma±6.3 Ma,时代为中侏罗世。岩石地球化学研究表明该岩石具有高钾钙碱性特征(K_2O+Na_2O=8.64%~9.62%,σ=2.44~2.69),准铝—弱过铝质(A/CNK=1.01~1.04),稀土含量高(ΣREE=273×10~(-6)~439×10~(-6),平均323×10~(-6)),LREE强烈富集,HREE轻度富集(La/Yb)N=10.87~16.21,平均13.68),较强的Eu负异常(δEu=0.18~0.26),总体呈向右缓倾斜的海鸥式,微量元素蛛网图上出现强烈富集Rb,Th,U,Pb,而亏损Ba,Sr,P,Ti,Eu,结合花岗岩成因类型判别图解确定其为A型花岗岩。综合区域上的研究成果,佛子冲中侏罗世正长花岗岩进一步佐证了华南地区在侏罗纪时,岩石圈发生了伸展作用,区域上是太平洋板块向西俯冲的一个地质响应。
According to zircon U-Pb zircon zircon LA-ICP-MS data, the age of the granodiorite from the Fuzhongchong area is 170.8 Ma ± 6.3 Ma, dating from Middle Jurassic world. Litho-geochemical studies show that the rocks have high K-Ca and Alkali (K_2O + Na_2O = 8.64% ~ 9.62%, σ = 2.44 ~ 2.69) (LREE = 273 × 10 -6 ~ 439 × 10 -6, average 323 × 10 -6), LREE strongly enriched and HREE slightly enriched (La / Yb) N = 10.87 ~ 16.21 with an average of 13.68). The strong Eu anomaly (δEu = 0.18 ~ 0.26) showed a generally seagull-like pattern inclined to the right, with strong accumulation of Rb, Th, U, Pb, The loss of Ba, Sr, P, Ti, Eu, combined with granite genetic type discrimination diagram to determine it is A-type granite. Based on the regional research results, the Fa-Chong-Middle Jurassic orthoclase granite further corroborates the extension of the lithosphere during the Jurassic in southern China and a geologic response to the western subduction of the Pacific plate in the area.