从再生珠边结构论银岩锡矿床的成因

银岩锡矿某些强蚀变矿石广为发育酸性岩浆快速结晶的“组分过冷”现象,具再生珠边结构和再生岛边结构。其中珠点状客晶矿物为黄玉、富锂(绢)云母和锡石等。结合其它典型的宏观、微观地质特征,借鉴国内外有关富挥发分酸性岩体系成岩、成矿实验资料,认为银者锡矿不是传统意义上的斑岩型矿床,应属于广义的云英斑岩矿床。其主体部分,主要是富挥发分、碱金属和成矿元素的低熔熔浆—溶液.在浅成、非平衡环境下、迅速冷凝结晶的直接产物。以此为例,笔者推出云英斑岩矿床的成岩、成矿模式。

FROM REGENERATED POIKILITIC TEXTURE OF PEARL MARGIN TO THE GENESIS OF YINYAN TIN DEPOSIT

It is well known that tin orebody is located within the Yinyan acidic porphyry and called as porphyry tin deposit. However, in some so - called strong altered ore zones, the supercooling crystallization of acidic magma i. e. regenerated poikilitic texture of pearl margin and regenerated poikilitic texture of islands margin are found in common. Some minerals such as topaz,Li-rich mica and cassiterite, which are regarded as single altered minerals by the traditional ideas, are pearl chadacryst minerals in regenerated margin of quartz phenocryst. According to other canonical macroscopic, microscopic geological features and the related petrogenetic, metallogenetic experimental data,the author thinks that Yinyan tin deposit is not porphyry ore deposit in traditional sense but should belong to "Greisen-porphyry ore deposit " or " Micro-xiaolongite ore deposit". Principal part of Yinyan tin deposit is chiefly direct and fast crystallization product of low-melting magma-solution rich in volatile components, alkili metals and ore- forming elements, under hypabyssal and non-balance conditions. For these reasons,to take Yinyan tin deposit for example, the author suggests the petrogenetic and metallogenetic model of "Greisen-porphyry" ore deposit".