粤北清远—英德地区震旦系含金性评价的地球化学准则

THE GEOCHEMTCAL CRITERIA TO DISCRIMINATE THE Au-BEARING PROPERTY OF METAMORPHIC SINIAN STRATA IN QI NGYUAN-YINGDE AREA NORTHERN GUANGDONG PROCINCE

本文对粤北清远,英德地区震旦系含金和不含金地层的金丰度,元素特征值和分布型式、地层中金和有关元素的特定组合、以及地层中金的矿物学占位等进行了较详细的研究,从而得出该地区震旦系地层含金性评价的7条地球化学推则。本文的研究思路及所提出的判别准则,对其它地区的地层含金性评价,也具有较重要的参考价值。

It is studied in detail in this paper that the contents and the association features of Au and othermicroelements, the distriution types, geochemical characterized values of Au and its distributions inminerals in the auriferous and nonauriferous metamorphic Sinian strata in Qingyuan-Yingde area,Northern Guangdong Province. Then, having compored the metallogenic element associations of theSinian strata with those of the three types of gold deposit in the auriferous Sinian strata, the authorspropose seven geochemical criteria to discriminate the Au-bearing property of Sinian strata in the area.Thus, the Sinian strata are auriferous when in them (1) Au is strongly concentrated and Au-abundanceis high. (2) the ratio Xg-Sa between the geometric mean value and the arithmetic mean value of Aucontent is relatively low and the ratio Cv between the standard deviation and the arithmetic mean valueis relatively high. (3) the histograms of Au-content are multitop and deviate from normal distribution.At the same time,the histograms of logarithm of Au-content are also multitop and deviate from normaldistribution. (4) the proportion of easily-released Au is relatively high. (5) element associations are thesame as or smilar to the metallogenic element associations of the gold deposits in the area. (6)the geo-logical history shown by element associations is the same as or similar to that shown by the metallo-genic element associations of the gold deposits in the area. Then on the contrary, the Sinian Strata arenonauriferous.