鄂尔多斯盆地与能源矿产有关的一些地球化学研究

【作者】 潘爱芳；

【导师】 赫英；

【作者基本信息】 西北大学 ， 地球化学， 2005， 博士

【摘要】 鄂尔多斯盆地是我国的一个巨型能源矿产聚集盆地,不同时代、不同类型的多种能源矿产同盆共存,为地质工作者从事科学研究提供了一个内容丰富的大型试验场。开展该盆地能源矿产地球化学及相关流体研究,不仅对丰富成藏（矿）理论本身具有重要作用,而且对寻找能源矿产新基地、扩大能源战略储备都有十分重要的意义。本文以国家973项目《多种能源矿产共存成藏（矿）机理与富集分布规律》（2003CB214600）为依托,通过对鄂尔多斯盆地能源矿产地球化学特征的研究获得了以下新的认识。 1、鄂尔多斯盆地地表元素地球化学场特征与深部构造特征中存在深部流体活动信息和能源矿产成藏（矿）信息。地表元素地球化学分区与能源矿产分布特征密切相关;盆地内壳内高导层和深大断裂为深部流体活动提供了基本条件,中生代以来的构造活动与地表元素地球化学场特征反映了深部流体仍在继续活动;基底断裂控制了多种能源矿产和地球化学场的分布特征;元素地球化学场特征在某种程度上反映出深部流体参与了盆地能源矿产成藏（矿）作用。 2、基底断裂带和构造活动强的区域,原油中元素组合复杂,并含有深源物质;元素地球化学特征和同位素特征反映部分能源矿产中含有深部流体成分;盆地内油气藏伴生水的物质来源较为复杂,具有多源性;元素地球化学特征显示东胜铀矿的铀源主要来自上地壳,灰白色高岭土化泥质粉砂岩及灰绿色粗砂岩对铀矿的形成具有重要的意义,灰色粗砂岩具有良好的找矿潜力;元素地球化学特征还表明,黑岱沟煤及煤层夹矸中微量元素来源于上地壳。 3、对能源矿产伴生氯仿沥青A的地球化学特征研究表明,石油沥青与石油具有相似的元素组合特征,反映它们在来源上具有某种程度上的同源性,但是石油沥青中所含的深部流体组分相对较高,且较石油经历了更复杂的后期演化;东胜含铀砂岩沥青主要属外来流体,与含铀砂岩所含的物质组分不具同源性,表明铀源并非由沥青等有机流体提供;各能源矿产中伴生沥青的来源和成因均有差异,表明盆地的流体活动具有多期性,是盆地演化不同阶段的产物:激光拉曼光谱特征显示,氯仿沥青中广泛存在还原性气体C₂H₂,C₂H₆,CH₄,C₂H₄等,其含量与氧化性气体CO₂具有互为消长关系,显示了氯仿沥青的后期改造和氧化-还原条件的变化特征。 4、能源矿产伴生流体的Q型聚类分析结果反映出石油的贼存层位以及所赋存的构造位置是影响其元素地球化学特征的主要因素:石油伴生水与石油有一定成因联系;陈家山煤层石油可能是石炭二叠系与侏罗系延安组煤成油的混合产物;侏罗系延安组石油和直罗组石油具有相似的流体活动特征和物质来源;侏罗系延安组煤和直罗组煤具有相似的沉积环境和后期演化特征;延安组石油沥青对铀的活化、迁移、富集具有重要作用;天然气伴生水与石油相关性较弱,但与石油沥青和煤沥青具有一定相关关系。 5、根据地球化学研究成果,提出了一套多种能源矿产成藏成矿标志,并据此标志圈出石油、天然气和煤的共生富集远景区2个,天然气和煤的共生富集远景区2个,石油与煤的共生富集远景区1个,铀矿富集区3个。更多还原

【Abstract】 Ordos Basin is one of the greatest Energy Mineral Diposits Gathering basins in China. Different epoch and most kinds of Energy Mineral Diposits are concurrent in this one basin, so Ordos Basin becomes a rich large-scale Experimental Site for geologic research activity. Geochemical analysis of the Energy Minerals and the relative fluid research in Ordos Basin becomes very important, not only for enhancing reservoir formation and mineralization theory, but for finding new Energy Minerals base and enlarging energy margin.This thesis depends on the National 973 Projects— "The formational mechanism, accumulation and distributionPatterns for multi-energy mineral deposits coexisting in the same basin(2003CB214605)" , in which, the geochemical characters of Energy Mineral Diposits has been analyzed. It is said:1、 Both of the nature of the geochemical field of surface elements and the feature of the deep structure suggest that there are deep fluid action and energy mineral reservoir formation and mineralization in Ordosie Basin. There is close relationship between the geochemical division and the energy mineral distribution. The intracrustal high conductive layer and the deep great fractures supply the basic condition for deep fluid action in this basin. The nature of the tectogenesis after Mesozoic era and the geochemical field of surface elements suggests that the deep fluid is still moving. The distribution of the Multi-energy Mineral Diposits and the geochemical field is controlled by the basement faults in the basin. In some way, the nature of the geochemical field shows that the deep fluid took part in the energy mineral reservoir formation and mineralization.2、 In zones with the strong tectonic activity and basement faults, the elements combination of petroleum is complex and the material from deep resource can be found in which. The character of elements geochemical and carbon isotope all show that there are deep fluid components in some Energy Minerals. The material source of the water accompanying with petroleum reservoir is complex, and which with multi-sources. The character of elements geochemical shows that the uranium of Dongsheng uran ore comes from the upper crust, the greyish-green gritstone and hoary kaolinised argillaceous siltstone is important for the formation of uranium deposits,and the grey gritstone is great potential to surveying uranium deposits . Which also shows that the trace elements in Heidaigou coal and its dirt are from the upper crust.3、 The geochemistry of Chloroform bitumen "A" accompanying with Energy Mineral Deposits has been studied, and the result said: elements combination of the asphalt is same as the one of petroleum, and the asphalt and the petroleum are with same sourcesin some way, but the deep fluid component in asphalt is relatively high, and even higher than the evolution degree of petroleum undergone in anaphase. Most of the asphalt in Dongsheng sandstone with uranium belongs to foreign fluid, whose source is different from the one of Dongsheng sandstone with uranium, and all of these show that the uranium resource is not this kind of fluid like asphalt. The difference in source and origin of the associated asphalt in energy mineral diposits suggests that the multistage action fluid in Ordosie Basin is the outcome of different stage evolution. The feature of laser Raman spectroscopy hints: The reducibility gas such as C2H2. C2H6, CH?, C2H4 can be found in chloroform asphalt extensively, whose content is growth and decline with the one of oxygenization gas CO2, and all of these show the feather about later reformation and redox condition for the chloroform asphalt.4> The result of Q-clustering analysis on the fluid accompanying with Energy Mineral Diposits says that the formation and the tectonic site the petroleum lying in mainly impact on its element geochemistry. There is some relation between petroleum and its associated water on origin. The petroleum in Chengjiashan coalbed maybe one kind of mixture mixed by the oil coming from the coal of Carbonic-Permian and Jurassic Yanan group. The Yanan group petroleum is with the same fluid activity character and material source as the one of Zhiluo group. Jurassic Yanan group and Zhiluo group are with the similar deposit environment and final evolving feature. The asphalt from Yanan group oil mainly affects on the activation, transportation and beneficiation of the uranium. The associated water with gas is with little dependence on the petroleum, but it correlate with the oil asphalt and the coal asphalt.5> Base on the result of geochemistry study, a set of identification of reservoir formation and mineralization for Multi-energy Mineral Diposits has been brought forward, and base on which, two possible oil-gas-coal intergrowth zones, two gas-coal intergrowth zones, one oil-coal intergrowth zone and three uranium enrichment zones are been marked out.更多还原