摘要
青海南部沱沱河地区的多才玛矿床是最近找矿突破发现的一个特大型铅锌矿床。由于赋矿规律不清,找矿方向不明,勘查曾一度陷入困境。针对制约找矿突破的关键地质问题,笔者开展了成矿潜力、矿床赋存规律、矿体定位预测研究,经钻探验证,实现了找矿突破。通过区域对比,认为沱沱河地区与"三江"带内兰坪等其他地区的地质背景相似,具有发育大型沉积岩容矿贱金属矿床的潜力;发现区域发育大型逆冲构造和含膏盐红层沉积、具有碳酸盐岩和暗色泥岩组合等,显示有利的成矿地质环境;区域和矿床内发育大规模高强度的铅锌化探异常,具有形成大型铅锌矿床的潜力。通过填图等研究,指出多才玛矿床为密西西比河谷型(MVT)矿床,产于逆冲推覆构造系统前锋带,矿体赋存于逆冲断裂上盘,受那益雄组碎屑岩和九十道班组灰岩岩相过渡部位及可能的逆冲推覆构造系统派生的反冲构造的控制,矿石主体为热液溶蚀角砾岩型。通过音频大地电磁测深测量,揭示了矿床深部物性特征和构造岩相特点,确定了孔莫陇矿段南侧深部铅锌矿化体的空间位置,并制定了钻探验证方案。经后期勘查,在预测区内探获了品位高、厚度大的铅锌矿体,使该矿段铅锌资源量由原来的76.2万吨增至259万吨,找矿取得重大突破。由此,通过综合分析,提出了一套综合地质、化探异常/矿化显示、地球物理、遥感等手段的多才玛式矿床定位预测方法组合。
The Duocaima ore deposit is a newly-found large Pb-Zn deposit in Tuotuohe area, Qinghai Province. Stu-dies of mineral prospect evaluation, ore controls, and localization-prognosis were carried out to solve the key problems in the process of mineral exploration. Regional correlation suggests that the Tuotuohe area has similar geological setting to the regions in ＂Sanjiang belt＂ （e. g. Lanping basin） that host many large sediment-hosted Pb-Zn deposits. The geological settings during the mineralization, i.e., thrust structure, sedimentation of red beds and development of carbonate adjacent to dark mudstone were favorable for Pb-Zn mineralization. In com- bination with extensive zinc-lead geochemical anomalies, the authors hold that the Duocaima area has good po- tential in search for large deposits. The Duocaima deposit is a carbonate-hosted, low-temperature, and epigenic deposit characterized by ores in breccia, no affinity with igneous activity, and involvement of sulfur generated by bacterial sulfate reduction, indicative of Mississippi Valley-type （MVT） origin. The ore body mainly occurs in fractured Permian limestone of the Jiushidaoban Formation （Pj） that is adjacent to Permian clastics of the Nayixiong Formation （Pn） and above a thrust fault. Audio magnetotelluric sounding measurements revealed resistivity distribution of several profiles, one of which determined the location of a potential underground ore body in southern Pj limestone of Kongmolong ore block. Based on these results, the authors successfully found thick and high-grade ore bodies, and Pb ＋ Zn metal tonnages increased from 0. 762 Mt to 2.59 Mt. The authors summarize the present and the previous studies and propose a mineral prospecting approach （integrated geologi- cal, geochemical, geophysical, and remote-sensing methods） for exploiting Duocaima-like Pb-Zn deposits.
出处
《矿床地质》
CAS
CSCD
北大核心
2013年第4期744-756,共13页
Mineral Deposits
基金
国家重点基础研究规划项目(2011CB403100
2009CB421008)
国家自然科学基金(41273050
U0933605
41102040)
IGCP/SIDA600项目
国家科技支撑项目(2006BAB01A08)
青海省沱沱河地区多金属成矿特征及找矿方向研究项目联合资助
关键词
地质学
成矿潜力
赋矿规律
音频大地电磁测深
定位预测
找矿突破
多才玛铅锌矿床
geology, mineral potential evaluation
ore controls
audio magnetotelluric sounding
localiza-tion-prognosis
mineral prospecting breakthrough
Duocaima Pb-Zn deposit
