中文摘要：

广西贵港大瑶山成矿带位于华南东南沿海成矿带西南端,对矿带内龙头山金矿黄铁矿化斑岩进行定年的结果为96.1±3.0Ma,与区域内邻近的平天山侵入岩体（96.2±0.4Ma）相同。龙头山矿床的Sr同位素组成与其锆石的REE特征表明,成矿作用伴随有大量的流体参与;矿化斑岩与区内侵入相岩石相同的形成时代以及矿化斑岩中锆石Ce的正异常明显强于侵入岩锆石的现象指示,成矿过程经历了快速的区域地壳抬升和体系氧逸度大幅增高;两类岩浆岩Nd同位素组成与华南低Nd模式年龄带相当,反映岩浆活动有不同比例的幔源物质参与。因此,大量成矿流体的参与、区域地壳抬升、流体沿深大断裂上迁过程中的突然冷却以及氧逸度增高是导致龙头山金矿成矿作用发生的重要条件;中生代古太平洋板块的低角度俯冲作用导致了区域地壳较大范围的流体释放,而地幔岩浆物质的板底垫托作用导致高溶解度成矿流体沿构造通道向上迁移,应是华南中生代大规模成矿发生的重要背景。

英文摘要：

The Dayaoshan golden metallogenic zone in the Guigang area, Guangxi province, is located at the southwest end of the southeastern coast polymetallic mineralization belt of the North China. LA-ICP-MS U-Pb dating for zircons from the pyrite-mineralized porphyry of the Longtoushan gold deposit in this region yielded a weighted mean 206Pb/238U age of 96.1±3.0 Ma, consistent with the results obtained from nearby Pingtianshan pluton （96.2±0.4 Ma） within the analytical error. Host rock Sr isotopic compositions and zircon REE features of the Longtoushan deposit reveal that the mineralization was accompanied with involvement of massive fluids. Mineralized porphyry, contemporaneous intrusive rocks, and distinctly higher Ce positive anomalies of zircons from mineralized porphyry than those from the intrusion imply a rapid uplifting of regional crust and pronounced rise of oxygen fugacity in magmatic system during the process of mineralization. Nd isotopic compositions of two magmatic rocks are similar to the low Nd model age belt of South China, indicating involvement of mantle-derived magmatic material with varied proportions during magmatic activities. Therefore, large-scale fluid involvement, rapid regional crustal uplift, abrupt cooling of ore-forming fluid upward along deep-seated fault, and oxygen fugacity increasing are key factors to result in the metallogenesis of the Longtoushan gold deposit. The low-angle subduction of the Mesozoic Pacific plate resulted in large-scale discharge of fluid in regional crust, and the underplating of mantle-derived magma resulted in the ascending of high-solubility mineralized fluid along the tectonic channels, which are the critical setting responsible for the large-scale metallogenesis along the southeastern coast of South China during the Mesozoic.