The Regularity of Gold Enrichment and Its Implications to Metallogenic Tectonics in Shuangwang Gold Deposit, Shaanxi Province

Shuangwang gold deposit is one of the largest crisis mines in Qinling area with special genetic type, and it is urgent for us to undertake prospecting. But different scholars have some controversy over the evolution of the metallogenic tectonic as well as over the ore-controlling mechanism in this deposit. This paper studies the relationship of spatial distribution among the breccia bodies, fractures and fissures, and gold grade taking KT5 ore body in the deposit for an example. The regularity of gold enrichment and its implications to metallogenic tectonics are discussed, combined with trend surface analysis. According to mineralization characteristics and the age of the mafic dyke swarms in the mine area, it is suggested that the ore-forming process happened mainly in Indosinian. Under the compressive stress from north to south during Indosinian orogenesis in Qinling area, two sides of the metallogenic fault sheared obliquely with rightward contortion in the early stage, which formed the rudiment of breccia belt. In the intermediate stage, earthquake and associated hydraulic fracturing, which were induced along with the fault movement, produced the main breccia bodies together with fractures and fissures; in the gold mineragenetic process, the brecciation trailed off, while the fractures and fissures developed continuously, and they played important roles of the main pathway as well as advantaged ore-forming space for metallogenic fluid, so the gold enrichment revealed planar distribution, and the change of the fractures and fissures occurrence was the basic factor that resulted in Au precipitation. In the late stage, the extension changed to east-west, and the mafic dyke swarms intruded in the setting, which were altered by metallogenic fluid.