【作者】 谭红兵；

【导师】 马海州；

【作者基本信息】 中国科学院研究生院（青海盐湖研究所 ） ， 地球化学， 2005， 博士

【摘要】 为扩大我国紧缺矿产资源——钾盐地质储量,建立有效的用于指导判断或寻找钾矿的新指标,论文以塔里木盆地西部为研究区,地表出露或矿硐盐岩、卤水为研究对象,选择元素、同位素地球化学为主要手段,对不同时空分布古盐岩沉积的海陆相特征、成盐古卤水蒸发浓缩、演化分异等问题进行了系统对比研究,并应用一些新建的地球化学找钾指标评价和预测了最有前景的找钾远景构造单元及相应的地层层位。论文涉及的主要内容可归纳为: 1) 回顾总结了过去古钾盐找矿研究中采用的主要地球化学方法及基本理论依据。 2) 分析了塔里木盆地不同构造单元、不同地质时代成钾有利与不利的构造、岩相古地理、地层、物源等宏观地质条件。 3) 对比讨论了不同时空分布的岩盐基本地球化学组成特征及同位素分布特征。 4) 通过卤水水化学系数、岩盐Br×10³/Cl系数,石盐氯同位素,石膏硫同位素及结晶水氧同位素地球化学多指标系统对比分析,联系其宏观成盐地质条件,初步论证了石盐δ³⁷Cl值、石膏δ³⁴S值及石膏结晶水;δ¹⁸O值作为贫Br岩盐沉积环境找钾指标的有效性。 5) 应用新的地球化学找钾指标,联系区域构造、岩相古地理特征,讨论分析了不同构造单元、不同地质时代成盐的海陆相沉积特征,成盐古卤水可能达到的最高蒸发浓缩阶段。 6) 通过多指标综合对比评价,预测了最有远景的找钾构造单元及相应有利成钾地层层位。 通过以上内容的对比研究,初步查明了塔里木盆地西部地表出露古岩盐的地球化学组成特征及沉积学特征,根据这些特征综合判断分析,塔里木盆地西部发育的两大次级成盐盆地——库车及莎车盆地成盐既有其共性,又有各自的特点。相同之处在于成盐规模巨大,且在最初的物源供给上都与古特提斯海海侵密切相更多还原

【Abstract】 It is well known that the resources of potash deposit in our country are very lack and cannot be satisfied to the developing requirement. Therefore, the paper focused on an issue about the ancient sylvite deposit formation in western Tarim Basin where many scientists regarded it as a promising area to find sylvite. The paper selected the western Tarim Basin as main research field, ancient salt rock and brine as study object, geochemistry as main methods. Through systematically and comprehensively contrastive research on ancient salt rock or brine distributed in different space and time, the paper analyzed their marine or continental sedimentary fades, paleo-brine evaporation and evolution. Then based on the research results, the paper prospected the most promising tectonic area and bearing strata to find sylvite deposit. The main content of the paper is as follows:a. The paper made a summary on common geochemical methods about ancient sylvite deposit exploration and summarized their basic theories in past years of sylvite-searching works.b. The paper analyzed the profitable and unfavorable geological conditions for sylvite deposit formation from the view of tectonic geology, sedimentary facies and paleogeography, strata and original source in different tectonic unit and geological periods in western Tarim Basin.c. The paper particularly expounded on the characteristics of geochemical composition and isotopic distribution of ancient salt rock through detailed contrastive analysis on those different tectonic units and periods in western Tarim Basin.d. It is proved in the paper that the isotopic value of 8 37C1 in salt, 5 34S in gypsum and also 6 18O in crystalline water of gypsum can be utilized as effective index to find sylvite deposit through comprehensively contrasted with typical hydrochemical features of brine, BrX 1O3/C1 ratio.e. Applying the newest index of potash salt-searching, referring on the characteristics of regional tectonic, sedimentary facies and paleogeography, the paper detailedly discussed and analyzed on the marine or continental sedimentary facies and the possible concentrated stages of the ancient brine that formed present exposed evaporates distributed in different space and time in the surface in western Tarim Basin.f. The research results in the paper prospected the most promising potash deposit-searching tectonic areas and the bearing favorable strata via multi-index evaluation in western Tarim Basin.Finally, the paper concluded that there had some commonness as well as more different respective characters to the salt rock sediment in the two largest sub-basins in Tarim— Kuqa-sub basin and Shaqa-sub basin. The commonness is that there deposit wide and thick salt rock and the original source of salt formation is connected with ancient Mid Sea water invasion. Besides, the content of typical marine elements like Bromine is much lower than those marine salts and the salts are also all lumped with clay minerals in both Kuqa and Shaqa sub-basin. As for differences, Shaqa-sub basin located in the tunnel of ancient Mid Sea water invasion and was always the first place to be flooded by sea water. The exposed salt rock in the surface mostly deposited in the late Cretaceous period and the sedimentary facies were more like marine environment. Moreover, the sedimentary stage of salt rock, especially the salt deposited in the late Cretaceous strata named Tuyiluoke formation in Kashi depression deposited much later than other regions. By contrast, the Kuqa sub-basin located far away from the heading of sea water invasion and the exposed salt rock mostly deposited in the early Tertiary period. The salt rock was intensely undergone great diagenesis and metamorphism by fresh water from Tianshan Mountain. Therefore, the sedimentary facies are more like continental environment. All thegeochemical indexes showed that the sedimentary stage of the salt rock in early Tertiary strata deposited relatively earlier than that in Kashi depression.In summary, according to the final research outcome, the Kashi depression in western Shaqa sub-basin should be proved as the most favorable and promising potash deposit-searching area and the late Cretaceous strata of Tuyiluoke formation (K2O may be the aim strata to find sylvite deposit. Certainly, those spring or river water with higher background content of Bromine and Boron in Yang Xia Depression in eastern Kuqa sub-basin may also have some clues to indicate the deep sylvite bearing minerals exist. So it is worth while to carry out more detailed research in future.更多还原