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采用锆石U-Pb法对武功山穹隆复式花岗岩中广泛分布的花岗质岩石开展精细定年研究,结果表明:山庄、张佳坊和武功山岩体的锆石U-Pb年龄分别为460.5±1.5 Ma、427.9±1.2 Ma和428.0±1.0-462.3±2.3 Ma,属早古生代晚期花岗岩;而雅山、温汤和明月山等岩体的锆石U-Pb年龄分别为161.0±1.0 Ma、143.8±1.6 Ma和126.3±6.4.Ma,属晚侏罗世-早白垩世花岗岩。因此认为武功山穹隆复式花岗岩中花岗岩分属早古生代晚期及晚侏罗世-早白垩世岩浆活动产物。从一个侧面说明华南地区大地构造演化过程中可能存在早古生代晚期构造一岩浆作用事件及晚侏罗世-早白垩世构造-岩浆作用事件,为华南大地构造演化研究提供了新的依据。结合前人在武功山地区花岗质片麻岩中白云母40Ar/39Ar法定年(225-233 Ma)资料,说明本区韧性变形形成于晚i叠世,可能意味着武功山伸展构造的启动时间,而晚侏罗世-早白垩世花岗岩浆的形成及向上运移,使周围的岩石软化乃至部分熔融,使得围岩环境更有利于伸展构造发展,并在早白垩世最终形成武功山花岗岩穹隆伸展构造。
Zircon U-Pb method was used to study the age of widely distributed granitic rocks in the Wugongshan dome granite.The results show that the zircon U-Pb ages of the Zirconograd, Zhangjiafang and Wugongshan granites are respectively 460.5 ± 1.5 Ma , 427.9 ± 1.2 Ma and 428.0 ± 1.0-462.3 ± 2.3 Ma, respectively, belonging to late Early Paleozoic granite. The zircon U-Pb ages of the Yaoshan, Wintang and Mingyueshan are 161.0 ± 1.0 Ma and 143.8 ± 1.6 Ma, respectively And 126.3 ± 6.4.Ma, belonging to Late Jurassic-Early Cretaceous granite. Therefore, it is considered that the granites in the Wugongshan dome granitic granitic belong to Late Early Paleozoic and Late Jurassic-Early Cretaceous magmatism. From one side, it shows that there may be Late Early Paleozoic tectono-magmatic events and Late Jurassic-Early Cretaceous tectono-magmatic events during the tectonic evolution of southern China, which provide a new basis for the study of the tectonic evolution of South China. Based on the 40Ar / 39Ar dating of 225-233 Ma muscovite in the granitic gneisses in the Wugongshan area, it is suggested that the ductile deformation in this area was formed in the late i-stratum, which may imply the start of the Wugongshan extensional structure Time. The formation and uplifting of late Jurassic-Early Cretaceous granitic magma soften and partially melt the surrounding rocks, making the surrounding rock environment more conducive to the development of extensional structures and finally forming the Wugongshan granite in the Early Cretaceous Dome extension structure.