云南北衙斑岩-矽卡岩金铜矿床三维可视化建模与应用

3D visualization modeling and application study of porphyry-skarn gold-copper deposits in Beiya Area,Yunnan Province

【研究目的】位于金沙江—红河巨型构造-岩浆成矿带中段的北衙超大型矿床(已探明金151.28 t,铜22.17万t),是三江特提斯成矿域东段典型的斑岩-矽卡岩型金多金属矿床。近年来,矿床浅部地质结构与资源状况已得到初步揭示,但是其深部地质结构、深部控矿构造及深部找矿潜力还不清楚,制约了深部的找矿发现。【研究方法】本研究以北衙金多金属矿床万硐山矿段1000 m以浅空间地质体作为研究对象,采用SKUA-GOCAD平台,选择“分块建模法”和“双面法”建立了万硐山矿段三维地质模型和金矿体模型;在此基础上,通过分析金元素空间变化特征,模拟变差函数,采用克里金插值法(Kriging)建立了规模矿体品位模型。【研究结果】结合品位模型和矿体模型,估算金矿资源量约为246 t,同时金元素品位空间分布显示沿万硐山矿段40°方向存在一条优势富集带。【结论】“双面法”相比“切片法”能快速准确地建立矿体三维模型;认为北东向(40°)金品位优势富集带为隐伏深大断裂浅部表现,金元素不仅在岩体与碳酸盐接触蚀变带中富集,也在距离岩体一定距离的隐伏断裂中富集,为未来深部找矿有利方向。

[Objective]Beiya supergiant deposit(explored Au: 151.28 t, Cu: 0.2217 Mt)located in the large-scale Jinsha river-Red river tectonic-magma-metallogenic belt, which is the typical porphyry Au polymetallic deposit in the southeastern margin area of Sanjiang-Tethys metallogenic domain. For the past few years, the shallow geological structure and resources of the deposit have been preliminarily revealed. However, its deep geological structure, deep ore-controlling structure and deep ore prospecting potential are still unclear, which restricts the prospecting and discovery of deep orebody.[Methods]In this paper, the shallow spatial geological body at 1000 m of Wandongshan ore block of the Beiya gold polymetallic deposit is taken as the research object. We choosing the "block modeling method" and the "double-sided method" to establish 3-D visualization of Wandongshan ore block and orebody model of Au deposit by using the SKUA-GOCAD platform. Further, Kriging interpolation was employed to acquire grade distribution model of Au based on analytical of spatial variation distribution characteristics and analog variogram.[Results]In the light of grade distribution model and orebody model, 246 t gold resource was assessed. Meanwhile, a dominant Au-enrichment belt was revealed along the 40° direction of Wandongshan ore block. [Conclusions]Compared with the "slice method", the "doublesided method" can quickly and accurately establishes the three-dimensional model of the ore body. It is believed that the NE trending(40°) gold-grade preponderant enrichment zone is manifested in the shallow part of the hidden deep and large fault, which demonstrate Au is not only enrichment in the contact-alteration zone between intrusion and carbonate, but also concentrated in buried fracture at a certain distance from the intrusion, which is a favorable spots for future deep ore prospecting.