西秦岭寨上金矿综合地球物理研究

Comprehensive geophysical study of Zhaishang gold deposit, West Qinling

寨上金矿是中国西秦岭构造带内一个重要的超大规模卡林—类卡林型金矿床。以往对该金矿床的研究主要集中在矿床学、年代学和成矿特征等方面,缺乏地球物理工作的系统梳理。本文以贯穿研究区的可控源音频大地电磁测深及激电工作为主体研究寨上金矿的深部结构,结合地质资料建立了矿区典型地质—地球物理解释模型,探讨成矿机制,总结寨上金矿赋矿标志,推测可能的矿体赋存位置和深度范围。研究表明,寨上金矿总体位于扎麻树—卓洛背斜,以区内深大断裂为界,分为成矿条件、深部电性结构均有所差异的南、北矿带两部分,矿化主要赋存于构造薄弱地带,区域地球物理证据表明近地表未出现大规模的岩浆侵入,其成矿物质来源主要与区域性深大断裂相关。

Objectives: Zhaishang gold deposit is an important super-large scale Carlin-like gold deposit in the west Qinling tectonic belt of China. Previous studies on this gold deposit mainly focus on mineral deposits, geochronology and metallogenic characteristics. It is important to systematically review the geophysical work in the study area to summarize the ore-occurrence rules and expand the deep prospecting space.Methods: In this paper, the deep structure of Zhaishang gold deposit is studied by using CSAMT and electromagnetics throughout the study area. Combined with regional geophysical anomaly and geological data, the typical geology—geophysical interpretation model is established to discuss the metallogenic mechanism and summarize the occurrence regularity of orebody.Results: The study shows that the Zhaishang gold mine is generally located on the Zamashue—Zhuoluo anticline. Taking the deep and large faults as the boundary, the region is divided into two parts, the south and the north ore belt, which have different metallogenic conditions and deep electrical structure. Furthermore, a set of comprehensive geophysical prospecting methods applied to deep prospecting in Zhaishang gold deposit is formed, which has been verified in the shallow overburden areas in the east—west extension direction of the south ore belt.Conclusions: Only through multi-scale and multi-method geophysical exploration can we provide a reasonable and comprehensive geological interpretation for complex large mining areas. The results show that there is no largescale magma intrusion near the surface, and the source of the mineral is mainly related to the regional deep and large faults. The tectonic weak parts of Zhaishang gold deposit is ore-controlling and ore-bearing structure with good regional metallogenic potential.