非传统金矿化探的理论与方法技术研究

UNCONVENTIONAL GEOCHEMICAL EXPLORATION FOR GOLD

传统的金矿化探方法已不能满足找矿的要求,特别是寻找隐伏矿的要求。为此我们根据过去十几年的研究提出了如下新的理论认识及相应的方法;(1)金在表生条件下不仅有其惰性的一面,而且更具有很强的活动性;(2)金不仅呈不均匀的颗粒存在,而且还大量做为超微细(亚微米级至纳米级和各种化合态)的分散金存在;(3)区域性大规模的金异常和隐伏矿上方的叠加含量异常是由易呈活动态的超微细分散金形成的;(4)为研究这类存在形式的金应大幅度降低金分析的检出限;(5)使之能发现大规模的区域性异常而成为战略性方法。基于以上理论考虑,本文提出了建立非传统金矿化探的方法学体系。并给出了两个地区的应用实例。

Conventional geochemical exploration for gold is based on the following theoretical considerations; (1) gold is chemically inert in surface environments, (2) gold occurs mainly in discrete grains, and (3) gold is transferred by mechanical means to form clastic dispersion halos and dispersion trains. The methodology adopted based on these theoretical considerations is : (1) determination of Au in concentrates and use of heavy minerals counting technique, (2) increase of the sample size in order to improve the reproducibility of gold analysis, (3) use of high detection lim- its and thresholds, (4) determination of total gold in the samples, and (5) tactical rather than strategic. These considerations and methodology have long dominated the design and implementation of geochemical exploration for gold.Such conventional geochemical exploration for gold has not always been very satisfactory, especially for buried and blind gold deposits. New considerations and methodology in sampling, analysis and interpretation have been developed in China during the past decade.Important considerations in unconventional gold exploration are that: (1) gold is active in surface environments; (2) gold occurs not only as discrete grains, but also as ultrafine particles and in other complex forms; (3) regional low anomalies and superimposed anomalies over buried gold deposits are created by ultrafine gold and other complex forms of gold.The methodology based on these considerations has been developed both in regional and in local geochemical exploration for gold.