华北地台沉积岩型金矿床的找矿勘查意义

Exploration significance of sediment hosted gold deposits in North China platform

冀东地区沉积岩型金矿床主要赋存在中上元古界长城系和蓟县系巨厚钙 -镁碳酸盐岩内 ,金矿化受层间角砾岩带控制。相比之下 ,内蒙古中西部沉积岩型金矿床主要产出在上元古界青白口系钙质粉砂岩和板岩内 ,矿体产状受层间构造破碎带控制。尽管上述金矿床的成矿环境、赋矿围岩和成矿时代存在一定差别 ,但是它们均以埋藏浅、规模大、物质组分简单和易选冶为特点。为了突出这两类金矿床的区域性特征 ,前者命名为“长城式”,后者则确定为“阿拉善式”。认真研究和总结上述两类金矿床地质、地球化学特征和找矿勘查标志 ,并将其应用于找矿实践将是华北地台新一轮找矿勘查的重要内容之一。

Sediment hosted gold deposits located in eastern Hebei are hosted by Middle to New Proterozoic Ca Mg carbonate rocks of Changcheng and Jixian Systems. The gold mineralization is controlled by intraformational breccia belt. In contrast, gold deposits located in central and western Inner Mongolia are hosted by New Proterozoic calcareous siltstone and slate of Qingbaikou System. The occurrence of the orebody is controlled by interstratified tectonic fracture zone. Although the mineralized environment hosted wall rocks and metallogenetic epochs of the above gold deposits are different, they are all characterized by shallow burial, large size, simple composition and easily mining. In order to stress the regional characteristics of the two types gold deposits, the former is named Changcheng type while the latter is called Alxa type. The geological, geochemical characteristics and exploration criteria of the two types gold deposits are summerized and used to the exploration.