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据1∶5万区域地质调查,大雁山岩体与上覆百足山组(K1b)呈不整合接触。对大雁山花岗闪长岩进行SHRIMP锆石U-Pb同位素定年,其谐和年龄为230.3±3.1 Ma(MSWD=3.1),表明大雁山岩体为印支期岩浆活动的产物。岩体Al2O3含量为13.72%~14.35%,A/CNK为1.08~1.26,Rb/Sr为3.27~6.24,微量元素组成与南岭印支期花岗岩较为相似,为典型的陆壳改造型花岗岩类。研究认为,大雁山岩体形成于印支地块与华南地块拼合过程中的同碰撞构造环境,其成岩作用与碰撞过程中的加厚地壳物质的部分熔融有关。
According to 1: 50000 regional geological survey, the Dayan Mountain rock body and the overlying Baizu Mountain Formation (K1b) showed unconformity contact. SHRIMP zircon U-Pb isotopic dating of Dayan Mountain granodiorite was carried out with a mean age of 230.3 ± 3.1 Ma (MSWD = 3.1), indicating that the Dayan Mountain pluton is the product of Indosinian magmatism. The content of Al2O3 is 13.72% ~ 14.35%, the A / CNK is 1.08 ~ 1.26 and the Rb / Sr is 3.27 ~ 6.24. The trace element composition is similar to that of the Nanling Indosinian granite, and is a typical continental crust granitic. The study suggests that the Dayan Mountain pluton was formed in the co-collision tectonic environment during the Indo-China massif and the South China massif, and its diagenesis is related to the partial melting of thickened crustal material during the collision.