甲马铜多金属矿床层控矽卡岩流体包裹体特征及其成因意义

甲马铜多金属矿床位于西藏冈底斯火山-岩浆弧中的一个弧后盆地,并赋存于该盆地上侏罗统多底沟组礁灰岩与下白垩统林布宗组下部的砂板岩之间,矿床的含矿岩石为矽卡岩.作者在对其地质特征分析的基础上,通过其中矿物流体包裹体的特征、均一温度、包裹体成分的研究,并与典型岩浆热液接触交代矽卡岩矿物流体包裹体和现代海底热(卤)水的对比,显示该矿床层状矽卡岩矿物的形成温度、流体成分与典型岩浆热液接触交代矽卡岩存在较大差异;而与现代海底热(卤)水有较大的相似性.因此,推断甲马矿床层状矽卡岩的形成与岩浆热液没有直接的成因联系,而很有可能是与盆地演化过程中的热(卤)水活动有关.

Characteristics and origin signification of ore-forming fluid from the Jiama stratabound skarn deposit located in Gandise volcanic-magmatic arc, Tibet, China

The Jiama copper and polymetal deposit is located in a back-arc sedimentary basin and occurs as stratiform and stratoid bodies in the transitional zone between the reef limestone(J_3d) and sandy slate(K_1l).Skarn as ore-bearing rock in the Jiama deposit,having particular geological characteristics,has been concerned greatly by investigators.On the basis of studies on the characters of the fluid inclusions in the minerals,such as homogenization temperature and composition,and compared with the fluid composition and temperature of the fluid inclusions from the Jiama skarn and typical skarn-type deposits,the hot brine in modern seafloor,this article holds that the formation temperature,fluid composition of the stratabound skarn mainerals in the Jiama deposit are different greatly from the typical skarn-type deposits,but are comparability similar to the hot brine from modern seafloor.So,the authors conclude that the stratabound skarn of the Jiama deposit has nothing to do with magma hydrothermal solution,and however,has likely something to do with the hot brine in the basin.