甘肃金山、马泉金矿床成因类型及其对比研究

Formation Types and Comparative Analysis of Jinshan and Maquan Gold Deposits in Gansu

金山、马泉金矿床是礼县-白云-山阳大断裂西段膨大、分支锐角夹持区的两个中型金矿床。通过对矿床区域地质背景、矿床地质特征、成因等要素的对比分析;对中川岩体及含金性特征及中石炭统、中泥盆统含金性的研究,认为金矿的金源应来自浅部地层。通过对石英样品δ18O的测定,认为矿石的主要物质成分——氧来自地层;通过成矿溶液水的氧氢同位素特征的测定,认为成矿溶液水是少量岩浆水渗入了大量的大气降水组成的混合热液水;通过分析硫同位素特征和稀土元素配分模式,认为硫具深源性,而稀土元素来自地层。对成矿物理化学条件的研究,认为在中低温弱矿化度、弱酸性、弱还原条件下成矿。中川岩体是矿床形成的热源体;矿床应属微细浸染型(即卡林型)金矿床。认为这2个矿床应属较大的金矿床,在以后的地质勘查中应统筹考虑、(特别是在两个矿床的结合部),以便扩大金矿床规模。

Jinshan and Maquan are two medium-sized gold deposits of a branch of the acute angle,which were formed by expansion of the western part of Lixian-Baiyun-Shanyang fault.We carried out the comparative analysis of the regional geological data and characteristics,and formation causes.Middle Devonian and Carboniferous,strata in the gold-bearing show that the gold sources of Maquan should come from the shallow strata;the analysis of the samples of quartz δ18O shows that the main physical component of the ore is oxygen from the strata; according to the characteristics of oxygen and hydrogen isotopes of ore-forming solution water, we get that the hydrothermal water was formed by a small amount of ore- forming solution percolated through a large number of meteoric water. The characteristics of sulfur isotopic and RE;E patterns show deep-derived sulfur, but the rare earth elements also from the strata. Through physical and chemical conditions of mineralization, the mineralization conditions should meet low- temperature weak salinity, weak acidity and weak reducing conditions. Zhongchuan rock body is a heat source body of the formation of the deposit. Infection-type deposits should be fine （Carlin-type） gold deposits. The geological survey in the future should consider overall （in particular, the combination of the two deposits）, so that we can realize the expansion of the existing deposits.