铜陵矿集区舒家店矿区中酸性侵入岩锆石U-Pb年代学研究

摘要

Intermediate-acidic intrusive rocks are well developed in Shujiadian area of Tongling region. The intrusive rocks are mainly composed of Shujiadian rock body, Linjiachong rock body and several minor rock bodies around them. The intrusive rocks in the area can be divided into high-K calc-alkaline series and shoshonite series. In this study, the authors carried out LA-ICP-MS zircon U-Pb chronological research on the two main rock bodies. The results show that there existed multiple phases in the intermediate-acidic rock intrusion events in this area. The intrusion ages of the granodiorite porphyry, the pyroxene monzodiorite, the quartz monzodiorite, the granodiorite, the granite porphyry and the felsic vein are between 147.0 Ma and 146.9 Ma, 144.8 Ma, 141.0 Ma, 138.0 Ma, between 130.5 Ma and 124.0 Ma, and 129.4 Ma, respectively. On such basis, the authors consider that the intruding order of the intermediate-acidic magma in this area should be granodiorite porphyry→pyroxene monzodiorite→quartz monzodiorite→granodiorite→granite porphyry or felsic vein.%铜陵舒家店地区中酸性侵入岩发育，主要由舒家店岩体、林家冲岩体及其周围的小岩体构成。区内侵入岩可划分为高钾钙碱性系列和橄榄安粗岩系列。对两个主要岩体的钻孔岩心采样并对其进行了LA-ICP-MS锆石U-Pb定年工作。研究结果表明，舒家店地区中酸性侵入岩活动存在多期性，花岗闪长斑岩侵入年龄在147.0~146.9 Ma，辉石二长闪长岩为144.8 Ma，石英二长闪长岩为141.0 Ma，花岗闪长岩为138.0 Ma，花岗斑岩在130.5~124.0 Ma，长英质细晶岩为129.4 Ma，并给出区内中酸性岩浆侵位先后次序为：花岗闪长斑岩→辉石二长闪长岩→石英二长闪长岩→花岗闪长岩→花岗斑岩脉/长英质岩脉。