金属矿脉（体）品位收缩的成因

我国找矿勘探及开采工作实践证明,一些金、铅、锌、钨、锡、钽、铌等金属矿脉(体)品位的垂直分布具收缩性质。国外一些同类矿床及铜、铀矿体(脉)亦呈同样性质。上述矿床的这一地质现象已经引起了地质工作者的注意,曾进行了描述或说明,但迄今未能查明其成因,本文拟阐明其成因。

The origin of tenor contraction of metallic ore veins or bodies

Some typical examples illustrating the tenor contraction of such metallic ore veins or bodies as Au, Pb, Zn, W, Sn, Ta and Nb have been recorded by Chinese geologists in the course of ore exploration and mining. The similar demonstrations have also been observed in Japan, Peru and the U.S.S.R. by their respective geologists. Yet its origin as a problem in the field of ore deposits remains unsolved. In this paper, by adopting the photon-based chemical thermodynamical method proposed by the author, the gravitational field position Z related to the intensity of the diffusion force of ore fluids are proved to be the leading factor causing the tenor contraction of metallic veins or bodies. The tenor contraction of metallic veins or bodies under suitable ore-controlling structural conditions is an objective fact in the science of ore deposits, though in no case should it be regarded as a rule to deny the necessity of searching for ore at depth. The variation of the deep-seated ore-controlling structures might alter the tenor of the metallic veins or bodies. The Taipushi wolframite deposits in Nei Monggol could be taken as a convincing example. The tungsten content increases at great depth owin,g to the dilatation during ore deposition along the schistosity of the Proterozoic crystalline schists. There also have been observed similar phenomena in other deposits of China.