典型构造蚀变岩型金矿远景资源量数学模型与预测

Mathematical modeling and estimation of reserves of typical structural altered rock type gold deposit

数学模型是矿床深部资源量定量化预测一个重要手段,其中品位-吨位模型是一个广泛应用的数学模型,在该模型中,远景资源量为研究区源岩中成矿元素总量的函数。利用该模型,计算胶东构造蚀变岩型金矿远景资源量时,发现由于成矿源岩范围难以确定,而使模型应用准确性受到制约。基于断裂带蚀变岩型金矿的特征,修正了品位-吨位模型。在修正后的模型中,远景资源量为蚀变岩总质量的函数,另包括3个参数:蚀变区元素背景含量(由多标度分形决定)、元素工业品位及矿体品位分布分维值。利用修正后的品位-吨位模型,有效地估算了胶东大尹格庄金矿-1000m以上的理想金属量,得出远景矿石量为5.26×107t,金属量为2.89×105kg,与实际地质情况相吻合。

Mathematical modeling is an important approach to estimating the deposit reserves, and the grade-tonnage model is widely applied. In the model, the ideal reserves are constrained by the following four parameters： the total element mass of the source rock （M0）, regional background value of element （C0）, mean production grade of element （C）, and fractal dimension of the grade and tonnage （D）. During the application of the to the reserve estimation of the Dayin gezhuang deposit, a typical structural altered rock type deposit in the Jiaodong ore cluster area, the authors found that the application was restricted due to the difficulty in defining the boundaries of the source rock. Based on basic features of the structural altered rock type deposit, the authors modified the grade-tonnage model so as to make an effective prediction of the reserves of the deposit. In the modified model, the same four parameters are endowed with different meanings： M0 is the total mass of altered rock, C is the mean element production-grade, Co is the element background value in the altered rock area estimated by the two-scale fractal model of the distribution of element grade, and D represents the fractal dimension in the larger scale of the fractal model. The ore reserves of the Dayingezhuang deposit estimated by this modified model are up to 5,26×10^7 ton, and the metal reserves are2.89×10^5 kg, showing a coherence between the estimated reserves and the geological conditions.