【作者】 刘珺；

【导师】 周涛发；

【作者基本信息】 合肥工业大学 ， 矿物学、岩石学、矿床学， 2005， 硕士

【摘要】 安徽庐枞火山盆地位于下扬子断陷带内,地处扬子板块北缘,西临郯庐断裂,接近华北与扬子两大板块的拼合带。该区既有橄榄安粗岩和与之相当的富钾侵入岩,又有埃达克岩。既有斑岩型铜矿(沙溪),又有火山—次火山热液脉型铜矿(拔茅山、井边、天头山)。本论文选择位于盆地中心的巴家滩岩体作为主要研究对象,从岩体地质地球化学特征着手,研究了巴家滩岩体的成岩过程及岩浆演化模式,认为巴家滩岩体的岩浆活动可分为2期:第一期主要为辉石二长岩和二长闪长岩类,现以包体形态产出;第二期主要为辉石二长岩、含英辉石二长岩等二长岩类和正长岩类,可分为3个阶段,分别是早阶段的辉石二长岩、中阶段的含英辉石二长岩等二长岩类,晚阶段则为正长岩类;成岩作用是分离结晶和同化混染联合作用。通过对巴家滩成岩成矿年代学、物理化学条件、地球化学特征等的详细研究,确定了巴家滩岩体的形成时代为135Ma,介于砖桥旋回和双庙旋回之间。探讨了与该岩体有关的铜矿化的成因,认为巴家滩主岩体的浸染状黄铁矿化是热液成因的;辉石二长岩包体中团块状的黄铜矿化、斑铜矿化则可能是巴家滩岩体深部可能存在早期的、规模较大的含矿(岩)体被携带上来。通过与该区的沙溪斑岩铜矿的对比,探讨了其铜矿化与埃达克质岩浆作用及相关的地球动力学过程之间的关系,得出巴家滩岩体属于埃达克质岩的范畴。在此基础上,评价了巴家滩岩体具有良好的成矿潜力。更多还原

【Abstract】 Luzong volcanic basin is located in the LowerYangtze Fault Belt, where is the north margin of Yangtze block. Mugearite, K-rich intrusions and adakite as well as porphyry copper deposit (Shaxi) and volcanic-subvolcanic hydrothermal vein type copper deposits (Bamoshan, Jinbian and Tiantoushan) outcrop in this district. The Bajiatan intrusion, which is sited in the center of the basin, is the main object of this research. Based on the geology and geochemical characteristic of the intrusion, we focus on the intrusion’s diagenetic process and magma evolution mechanism. The study shows that the magma activities of Bajiatan intusion can be divided into two stages: the early stage magma activity formed pyroxene monzonite and monzodiorite as enclosures in the main intrusion, the later stage formed monzonite and quartz-bearing monzonite. The later stage of magma activity can be divided into three phases, the early pyroxene monzonite phase, the middle quartz-bearing monzonite phase and late syenite phase. The main diagenesis is fractional crystallization assimilation and contamination. The age of Bajiatan rockbody has been determined to be 135Ma using zircon U-Pb SHRIMP dating, indicating the Bajiatan rockbody formed at time between the Zhuanqiao Cycle and the Shuangmiao Cycle. The genesis of copper metallogenic in Bjiatan intrusion has been discussed. Disseminated pyritization is related to hydrothermal activity, while the nodule-like chalcopyrite and bornite may be formed in the deep and carried to the surface by intrusion. Compared with the Shaxi porphyry copper, the Bajiatan intrusion is thought to be Adakitic rocks. The Bajiatan intrusion has good mineralization potential.更多还原