The discovery of late Paleozoic magmatism in Tongling area：Evidence from zircon U-Pb dating of diabse in Fenghuangshan ZK 66 drilling core

Abstract：Fenghuangshan granodiorite with an outcropped area of approximately 10 km2 is the largest pluton in Tongling area, belonging to high-K calc-alkaline series. ZK 66 drill hole at Zhujiashan located in the northwest corner of the Fenghuangshan pluton revealed that the pluton overlaps on the top of Triassic carbonate strata. Besides the granodiorite seen in the shallow part of the ZK 66 drill hole, the Late Devonian-Permian strata can also be found in the depth of the drill hole. Especially, the diabase with an age of 304 Ma and the granite porphyry with an age of 132 Ma were found in the Carboniferous marble, indicating the existence of late Paleozoic magmatism and probably the Mesozoic granite magmatism which lasted until 132Ma. The discovery of the late Carboniferous diabase reveals a sea-floor spreading environment and also indicates the close genetic relationship between the marine exhalation and the magmatism, which laid a solid foundation for the formation of a large ore deposit in that period.