长江中下游成矿带矽卡岩型矿床矿物包裹体激光拉曼分析结果及其地质-地球化学意义

矽卡岩矿床各种硅酸盐矿物中熔融包裹体和流体-熔融包裹体的显微测温资料和相成分让我们提出过大量矽卡岩是岩浆成因的建议。在本文中,我们提供沿长江中下游成矿带的许多矽卡岩矿床包含在石榴子石和辉石里的熔融包裹体和流体-熔融包裹体的激光拉曼分析结果,目的是证明所研究的并与Cu-Fe-Au矿床共生的矽卡岩系岩浆成因。我们的研究结果显示,熔融包裹体只含固体相和微量气相。流体-熔融包裹体除了含大量固相外,还含微量流体和气相以及没有被仪器检测到的气体。固体相与包裹体寄主矿物相同或类似。流体相主要为水或盐水溶液和包括C6H6、C3H6、C3H8、CH4、CO2和O2的气体。我们提出,熔融包裹体和流体-熔融包裹体是原始岩浆的最好代表。这就证明,矽卡岩组合是由一个原生岩浆直接结晶而成。此外,我们还讨论了岩浆矽卡岩形成的温度、分布范围和规模、形成机制和与Cu-Fe-Au矿化作用的联系。

Laser Raman analysis results of mineral inclusions from deposit of skarn type distributed in the Middle and Lower Reaches Metallogenic Belt of Yangtze River, China and their geological-geochemical significance

Microthermometric data and phase compositions of melt and fluid-melt inclusions in a variety of silicate minerals from skarn deposits have led to proposal that a large amounts of skarns are of magmatic in origin of skarns. In this paper, we present results of Laser Raman spectroscoic analysis of melt inclusions and fluid-melt inclusions hosted in garnet and pyroxene from a number of skarn deposits along the Middle-Lower Yangtze Metallogenic Belt (MLYMB) to confirm the magmatic origin of the skarns investigated and associated Cu-Fe-Au deposits. Our results show that the melt inclusions contain only the solid phase and the trace gas phase. The fluid-melt inclusions contain, in addition to a large amount of solid phase, a trace fluid phase and a gas phase and a gas phase that is not detected by the instrument. The solid phases are of the same or similar to the host mineral of the inclusions, the fluid phases predominantly are water or salt aqueous solutions and gaseous phases including C₆H₆, C₃H₆, C₃H₈, CH₄, CO₂ and O₂. We suggest that the melt and fluid-melt inclusions are best representatives of the pristine magmas, and thus demonstrate the formation of the skarn assemblages by direct crystallization from a parent magma. In addition, we discuss the formation temperature, distribution range and scale of the magmatic skarns, the formation mechanism and the genetic relationship with Cu-Fe-Au mineralization.