皖南天井山地区燕山期岩浆作用及成矿

发布时间：2018-06-03 20:35

  本文选题：锆石U-Pb定年 + Hf同位素　； 参考：《合肥工业大学》2015年硕士论文

【摘要】：天井山金矿处于江南造山带的东段,安徽皖南地区,发育于皖浙赣断裂带的次级断裂：璜茅-三阳-屯溪韧性剪切带中。天井山金矿周围的岩浆活动主要集中于晋宁期和燕山期,晋宁期的花岗岩为灵山岩体,约占天井山矿区面积的三分之二,产于矿区的南东侧。燕山期的花岗斑岩大多沿井谭组和灵山岩体的断层侵入,呈岩枝、岩脉产出,其中青山-长陔岩带在区域构造地质背景上与天井山成矿密切相关。天井山金矿产于灵山岩体与围岩接触带中,呈脉状,透镜状分布,以石英脉型和蚀变岩型矿石为主。矿石矿物以自然金、硫化物为主,蚀变类型主要有硅化、绿泥石化、绢云母化,石英脉的流体包裹体温度在286～380℃,盐度在3.0%～6.12%NaCleq之间,属于典型的岩浆热液性金矿特征。H-O同位素落在岩浆水范围,天井山金矿为岩浆热液型金矿。青山-长陔岩带为Ⅰ型花岗岩,具有弱过铝质的高钾钙碱性系列,其中青山岩体(QS001-1)年龄为150.3±1.7 Ma,长陔岩体(14QC001-1)年龄为140.3±2.6 Ma,长陔岩体(14QC002-5)年龄为141.0±2.4 Ma,古祝岩体(14QC004-1)年龄为141.0±3.0 Ma,石门乡(早山)岩体(14QC005-2)年龄为140.6±2.2 Ma,大岭脚岩体(14QC006-1)为141.0±2.0 Ma,形成于燕山期晚侏罗世-早白垩世。该系列岩浆岩轻稀土元素相对富集,重稀土元素相对平坦的右倾型分配模式,锆石Hf同位素指示青山-长陔岩带岩浆岩具有壳幔混熔的特点。青山-长陔岩带岩浆岩经历了角闪石、磷灰石、榍石和长英质等矿物的分离结晶,其岩浆岩源区与皖南地区出露的新元古代和中元古代基底关系密切,早期岩浆产生的构造背景属于大陆岛弧环境,而晚期处于拉张的构造背景,构造背景的转换为古太平岩板块向欧亚板块俯冲所致。
[Abstract]:The Tianjingshan gold deposit is located in the eastern section of the Jiangnan orogenic belt and in the south of Anhui province, and developed in the secondary fault zone of the Anhui, Zhejiang and Jiangxi fault zones: Huangmao-Sanyang-Tunxi ductile shear zone. The magmatic activities around the Tianjingshan gold deposit are mainly concentrated in Jinning and Yanshanian periods. The granite in Jinning period is Lingshan rock body, accounting for about 2/3 of the area of Tianjingshan mining area, and occurs in the east and south of the mining area. Most of Yanshanian granitic porphyry intruded along the fault of Jingtan formation and Lingshan rock body, which appeared as branches and veins, among which the Qingshan-Changyan belt was closely related to the mineralization of Tianjingshan in the regional tectonic geological setting. The Tianjingshan gold deposit is in the contact zone between Lingshan rock mass and surrounding rock. It is vein-like and lenticular, mainly of quartz vein type and altered rock type ore. The ore minerals are mainly natural gold and sulfides, and the alteration types are mainly silicification, greenstone, sericite, fluid inclusion temperature of quartz veins at 2866 ~ 380 鈩，

本文编号：1974093