中国钾盐矿产基地成矿规律与深部探测技术示范

本项研究得到国家“十三五”重点研发计划支持,系“深地资源勘探开采专项”2017年启动的重点项目之一,由中国地质调查局中国地质科学院矿产资源研究所牵头,来自自然资源部、中国科学院、教育部、大型石油国企等10家骨干单位以及多家协作单位参加,联合开展协同创新研究,充分体现“产研学用”密切融合。本项研究聚焦“特提斯东段中生代(三叠纪、侏罗纪)海相成钾作用与后期改造、青藏高原北部柴达木盆地深层富钾卤水迁移-分异-汇聚成矿机制”的关键科学问题和“深部含钾盐系‘双复杂’高精度地震成像技术、深部钾盐矿层(富钾卤水层)测井识别与地震预测技术”的关键技术问题,以柴达木西部和川东北两个重点成钾区为资源基地落脚点,兼顾其他含钾盆地研究,建立三维地质模型和成矿模型,完善海、陆相成钾理论,形成3 000 m以浅钾盐勘探成套技术能力,综合评价深部钾盐资源潜力,实施异常验证钻探,新发现1个大型钾盐资源基地,值得综合评价的有利成钾远景区3~4处,实现深部钾盐找矿突破和增储示范。值得强调的是,只有立足国内,突破海相,在中西部大中型叠合盆地古代海相蒸发岩地层中找到大规模海相可溶性固体钾盐矿床,方能从根本上扭转中国钾盐资源严重短缺的被动局面。令人欣慰的是,通过近10年的艰苦努力,我国海相钾盐取得了一系列成矿理论新认识和钾盐找矿新发现:创新提出了滇西南“二层楼”成钾模式,指出侏罗纪海相找钾新方向;在川东北宣汉普光地区发现三叠系海相可溶性“新型杂卤石钾盐矿”,开拓了四川盆地海相找钾新领域和新方向;在新疆库车地区发现埋深超5 000 m的钾石盐矿层,取得了库车坳陷海相找钾的实质性进展;创新提出“W型复底锅”成钾模式,在陕北奥陶纪海相盐盆发现厚层钾石盐矿化段,取得古陆表海型钾盐找矿重要新进展。至此,中国海相钾盐找矿崭露了突破的曙光。如何在这些新发现的基础上,进一步加大投入、深入研究,取得海相可溶性钾盐找矿的实质性突破,落实建成若干大型以上海相钾盐资源基地,将是“十四五”及以后时期中国钾盐的主攻方向。

Metallogenic models of potassium ore deposits in China and demonstration of deep exploration technology

This research project is a key component of the Special Projects for Exploration and Exploitation of Deep Earth Resources launched in 2017 and supported by the national 13^th“Five-Year”Key Research and Development Plan. It is led by the Institute of Mineral Resources, Chinese Academy of Geological Sciences and China Geological Survey involving 10 major research centers from the Ministry of Natural Resources, Chinese Academy of Sciences, Ministry of Education and large state-owned oil companies, as well as several research groups, for collaborative innovation research that fully reflects the close integration of production, research, learning and application. This research focuses on the key scientific issues of potassium formation in Mesozoic (Triassic, Jurassic) marine environments and late stage transformation in the eastern Tethys, and the ‘migration-differentiation-convergence’ mineralization mechanism of deep potassium-rich brines in Qaidam Basin, northern Qinghai-Tibetan Plateau. The key technical problems of the project are the ‘dual complexity’ high-precision seismic imaging technology for deep potassic salt deposit and the logging identification and seismic prediction technologies for deep potassium ore bed (potassium-rich brine layer). Taking the major potassium-bearing areas of western Qaidam Basin and northeastern Sichuan Basin as the foothold of the ore base, and also considering other potassium-bearing basins, the research program is designed to establish the 3D geological and metallogenic models, improve the theory of potassium formation in both marine and continental environments, and establish a complete technical system for the exploration of potassium deposits no deeper than 3000 meters. So far, comprehensive evaluation of deep potassium resources potential and anomalous verification drilling have been carried out, which led to the discovery of a large potassium resource base and 3-4 favorable target areas for potassium deposits. We have finally made the breakthrough in deep potassium ore prospecting and improved the prospects for greater potassium reserves. It is worth emphasizing that only by focusing on domestic exploration, and breaking through in marine environment to find large-scale soluble solid potassium salt deposits in ancient marine evaporite strata in large and medium-sized superposed basins in central and western China, can we fundamentally reverse severe shortage of potassium resources in China. It is gratifying to see a series of new metallogenic theories and prospecting discoveries have been made for marine potassium salt deposits in China after nearly 10 years of hard work. The innovative ‘two-storey’ potassium formation model put forth in southwest Yunnan points to a new direction for the exploration of Jurassic marine potassium salt deposits, and the discovery of a new type of Triassic marine soluble polyhalite potassium ore in Xuanhan area, northeastern Sichuan, leads to a new research field and direction for the exploration of potassium deposits in the Sichuan basin. In the Kuqa area of Xinjiang, a sylvine ore bed with a depth of more than 5000 m has been discovered to show substantial progress in the marine potassium deposit prospecting in this area. And in northern Shaanxi, the ‘W-type double bottom pot’ potassium formation model contributed to the discovery of a thick sylvine mineralization section in the Ordovician marine salt basin, a new important progress in exploring potassium salt deposits formed in the ancient epicontinental sea. Presently, we are at the dawn of breakthroughs in ore prospecting for marine soluble potassium salt deposits in China. The main direction for exploration of potash salts deposits in China in the 14th “Five-Year” and beyond will be to achieve substantial breakthroughs in this field thus to build several large marine potassium salt resource bases, through greater investment and more in-depth research on the basis of the aforementioned new discoveries.