三江中段新特提斯阶段区域流体的性质与状态

Regional fluid charecters and regimes of "Sanjiang" middle belt during Neo-Tethys.

对西南三江地区中段各类脉体开展了系统的流体包裹体和部分稳定同位素成分的研究 ,探讨新特提斯阶段区域流体状态及对区域成矿条件的影响。研究表明 ,三江中段新特提斯阶段区域流体存在两个性质不同的流体作用区域。中咱地块以西的兰坪盆地和澜沧江 -金沙江构造带主要属于低温流体作用域 ,区域流体以 Na Cl类 - H2 O体系成分为特征 ,中低盐度 ,流动和沉淀过程中的温度不高于 2 80℃ ,其水体部分主要来自大气降水的下渗和汇聚 ;中咱地块以东的雪鸡坪 -浪都地区属中 -低温流体作用域 ,区域流体先后受到燕山期和喜山期岩浆侵入活动的控制 ,在这两类侵入体附近的区域性流体分别以 Na Cl类 - H2 O体系和 CO2 - Na Cl- H2 O成分体系为特征 ,循环的大气降水和平衡岩浆水 -大气降水的混合水体是本流域区域性流体和成矿流体的主要来源。三江地区中段在新特提斯阶段长期处于碰撞挤压状态 ,区域流体流动的规模和延深受到断裂系统较高封闭程度的限制 ,不利于广泛产生大规模的多金属矿化。重要的金属矿化的出现都是在这个背景下叠加了两类高浓集作用效率的地质

Study of fluid inclusions and stable isotopic compositions has been finished for types of veins in 'Sanjiang' (Lancangjiang, Jinshajiang and Nujiang rivers) middle belt, southwestern China, in order to characterize the regional fluid regimes during Neo Tethys and for it to influence on the regional ore forming conditions. The result shows that there were two different fluid flow areas in 'Sanjiang' middle belt during Neo Tethys. Lanping basin and Lancangjiang Jinshajiang structure zones to the west of Zhongza block mainly belong to low temperature fluid flow area and regional fluids are characterized by NaCl H 2O rich composition, mid low salinities, not higher than 280℃ of trapping temperature, the waters in the fluids coming from penetration and focus of meteoric waters. Xuejiping Langdu area to the east of Zhongza block mainly belongs to mid low temperature fluid flow area and regional fluids are separately characterized by NaCl-H 2O-rich and CO 2-NaCl-H 2O-rich compositions, controled by magmatic intrusions succesively during Yanshanian and Himalayan periods. The waters in these fluids should come mainly from both meteoric waters and mixing waters between meteoric waters and waters in equilibrium with magmatic rocks. 'Sanjiang' middle belt mainly has been in compressional regimes caused by collision since the end of Paleo Tethys and the flow scale and penetration depth of the regional fluids were largely limited by higher closed-system behaviour of fractures and faults. This fact suggests that the fluid tectonic regimes should not devote to forming the widespread polymetallic mineralization for industrial use. The important polymetallic mineralization in the area was the results of the two geological geochemical processes with high concentration overprinted on this geological background.