鄂尔多斯盆地深层寒武系海相沉积是重要的勘探领域。从基础地质研究入手，通过系统研究盆地周边露头剖面及盆地内钻遇寒武系的探井资料、重点分析寒武系岩性岩相特征及分布特点、采集寒武系暗色岩石样品并进行TOC、氯仿沥青“A”等分析测试。结果表明，鄂尔多斯盆地深层寒武系分布稳定，厚度约为50～800m，主要由缓坡—台地相碳酸盐岩及混积缓坡—深水相泥岩、碳酸盐岩组成|盆地南中部寒武系馒头组黑色泥岩及三山子组深灰色、灰黑色纹层状白云岩形成于还原环境，有机质含量相对较高(TOC最高值为0.34%)，具有一定的生烃潜力。寒武系及其暗色岩类在贺兰奥拉谷和歧山—延安奥拉谷厚度明显增大，TOC值也明显增高，在环县、定边地区也有TOC高值区出现，表明了奥拉谷是鄂尔多斯盆地寒武系主要烃源岩发育区，预测可与中央古陆隆起带及其斜坡区形成有效的生烃—聚集成藏组合，鄂尔多斯盆地寒武系是值得进一步研究和勘探的重要层系。

<p>The Cambrian is an important prospecting field in the deep of Ordos Basin.According to the basic geological data in this area,and systematical study on the field geological outcrop profiles surrounding the basin and the Cambrian cores,the characteristics of the Cambrian lithology,lithofacies and distribution are emphatically analyzed.The Cambrian dark rocks were sampled and tested on TOC.The results show that the Cambrian has stable distribution with 50-800m thickness,belonging to ramp-platform facies and mixing ramp-deep water facies.Carbonate is developed in the ramp-platform facies mudstone and carbonate are developed in the mixing ramp-deep water facies.The Mantou Formation black mudstone and the Sanshanzi Formation lamellar dolomite have 0.34% TOC in the southern central basin.Especially,the above lamellar dolomite flings off odour (H₂S) which means it formed in a reducing environment.On the both sides of &ldquo;the central ancient land&rdquo;,namely the Helan aulacogen and the Qishan-Yanan aulacogen,Cambrian and its mudstones are thicker,and the total organic carbon is higher too.Besides,the areas with high total organic carbon appear in the Huanxian County,Gansu Province and Dingbian County,Shaanxi Province which lie on &ldquo;the central ancient land&rdquo; too.These show the aulacogens may be a developed area of main Cambrian source rocks.The aulacogens,&ldquo;the central ancient land&rdquo; and its slope area may form some effective reservoir-forming assemblages.The Cambrian in the Ordos Basin possesses the hydrocarbon-generating capability and needs further study and exploration.</p>

鄂尔多斯盆地南缘洛南和周家河地区发育下寒武统高丰度海相烃源岩，岩性主要为页岩，局部发生了动力变质作用，为泥板岩。有机地球化学分析结果表明，该套烃源岩厚度约为0~80 m，有机碳含量（TOC）介于0.10%~13.75%之间，均值为3.32%，其中91%的样品TOC含量大于1%，52%的样品TOC含量大于2%。有机质类型以II₁型为主，部分为I型。烃源岩总体达到了较高的热演化程度，沥青等效镜质体反射率介于2.25%~2.71%之间，甲基菲比值F₁为0.46~0.60，评价为优质气源岩。尽管鄂尔多斯盆地寒武系—奥陶系时期，受到加里东和怀远运动的影响而遭受抬升剥蚀，但庆阳古隆起及以南地区寒武系—奥陶系的地层产状总体保持向南倾斜，故北秦岭—洛南地区发育的下寒武统海相烃源岩生成的油气能向庆阳古隆起方向运聚成藏。鄂尔多斯盆地南部寒武系天然气与四川盆地高磨地区寒武系油型气在同一区域，为反序列油型气。寒武系天然气中乙烷碳同位素值在鄂尔多斯盆地下古生界天然气中最低，甲烷碳同位素值与下寒武统烃源岩干酪根碳同位素值分布相似，这为揭示下寒武统烃源岩对鄂尔多斯盆地南部天然气的成藏的贡献提供了直接证据。其次，盆地南部发现的寒武系储层沥青与下寒武统烃源岩的亲缘关系则为寒武系天然气成藏的间接证据。

The marine source rocks of Lower Cambrian are mainly developed in Luonan and Zhoujiahe areas in the southern margin of Ordos Basin. The lithology of source rocks is mainly shale， with local dynamic metamorphism and argillaceous slate. The organic geochemical analysis shows that the thickness of the source rock is about 0-80 m， and the total organic carbon content （ TOC） is between 0.10% and 13.75%， with an average of 3.32%. 91% of the samples have TOC content greater than 1%， and 52% of the samples have TOC content greater than 2%. The type of organic matter is mainly type II₁， with a small amount of type I. The source rocks have experienced a high degree of thermal evolution， with equivalent vitrinite reflectance of 2.25% - 2.71% and the methylphenanthrene ratio （F₁） between 0.46 and 0.60. The overall evaluation is high quality gas source rocks. Although the Cambrian-Ordovician was uplifted and eroded by the Caledonian and Huaiyuan Movements in the Ordos Basin， the Cambrian-Ordovician strata in the Qingyang paleo-uplift and the area to the south remained generally inclined to the south， the oil and gas generated from the Lower Cambrian marine source rocks developed in the North Qinling-Luonan area can migrate and accumulate in the direction of the Qingyang paleo-uplift. The characteristics of Cambrian natural gas in the south of Ordos Basin are similar to those in Gaomo area of Sichuan Basin， and they are both carbon isotope reverse sequence oil type gas. The carbon isotope of ethane from Cambrian natural gas is the lightest in the Lower Paleozoic， and the carbon isotope distribution of methane is similar to that of kerogen in the Lower Cambrian source rocks. There are direct evidences that the Lower Cambrian source rocks have contributed to the hydrocarbon accumulation of natural gas in the southern Ordos Basin. Besides， the relationship between Cambrian reservoir bitumen and Lower Cambrian source rocks in the south of the basin is the indirect evidence of the Cambrian gas accumulation in the south of the basin.

<p>Based on the study of field outcrops, core, logging and seismic data, seven lithofacies palaeogeography maps were prepared for the Cambrian sequences and system tracts in Ordos Basin in a 3rd-order sequence stratigraphic framework using the single factor analysis and comprehensive mapping method in accord with the theory of sequence stratigraphy. Overall, the sequence lithofacies palaeogeography of the Cambrian evolved from carbonate ramps with alternative occurrence of clear water and muddy water(Qiandong Epoch to Taijiang Age of Wuling Epoch) to rimmed carbonate platforms with clear water(Wangcun Age of Wuling Epoch to Furong Epoch), and the palaeoclimate changed from an arid type to a relatively humid type. In the Early Cambrian(Qiandong Epoch), i.e., deposition period of Xinji Formation, Zhushadong Formation and the lower Member of Mantou Formation, there were typical characteristics of south sea-north continent. In the Middle Cambrian(Taijiang Age of Wuling Epoch), i.e., deposition period of the middle and upper Member of Mantou Formation, the original Ordos oldland was separated into 3 oldlands due to continuous transgression, including Yimeng oldland, L&uuml;liang oldland and Zhenyuan oldland. In the Wangcun Age of Wuling Epoch(Cambrian), i.e., deposition period of Zhangxia Formation, the transgression occurred on the largest scale, thus developing the rudiment of central paleouplift and the palaeogeographic framework of east-west differentiation in Ordos Basin. In the Late Cambrian(Guzhang Age of Wuling Epoch to Furong Epoch), i.e., deposition period of the middle and lower Member of Sanshanzi Formation, the marine regression occurred and led to the formation of Yimeng-central oldland in a south-north direction. In the Early and Middle Cambrian(Qiandong Epoch to Taijiang Age of Wuling Epoch), tidal flat facies was dominant in Ordos Basin, whereas in the Late Cambrian(Wangcun Age of Wuling Epoch to Furong Epoch), restricted platform facies occurred in the largest area. In Zhangxia Formation and the upper Member of Mantou Formation, oolitic shoals were mainly distributed around the inner ramps and open platforms, i.e., within the middle ramp and platform margin; whereas in Sanshanzi Formation, porous dolomites were widely distributed in the strata.</p>

综合利用地震、测井、钻井和露头等资料,对鄂尔多斯盆地寒武系断裂特征及其对沉积储集层的控制作用进行研究。研究结果表明：①寒武系发育北东向、近东西向和北西向3组断裂,其中北东向和近东西向断裂是寒武系的主干断裂,以正断层为主,为同沉积断裂。②根据断裂在构造单元中的作用不同并参考断裂规模差异,将寒武系的断裂分为3个级别,其中二级断裂控制鄂尔多斯盆地寒武系凹陷的边界且断裂规模较大,三级断裂主要控制局部构造的高、低起伏,规模较二级断裂小,四级断裂是在局部构造单元内发育的调节断层,断裂规模很小。③寒武系断裂对沉积储集层具有重要的控制作用。受二级、三级断裂控制,形成了寒武纪凹凸相间的宏观构造和高低分异的微观地貌相结合的古地理格局,这种古地理格局不仅控制了寒武系滩相的发育,同时也控制了优质储集层的分布。④受断裂控制,紧邻寒武系凹陷边缘的微古地貌高部位是有利的勘探区。图14参33

鄂尔多斯盆地为典型的克拉通内盆地，油、气、煤、盐、铀等矿产资源丰富。研究构造运动的期次、序列与性质将为揭示克拉通盆地的成因与演化过程奠定基础，同时也将为探讨多种能源、矿产资源赋存的内在机制提供依据。基于近年来的高精度区域反射地震剖面和深井资料，结合周缘地质露头分析，通过厘定鄂尔多斯盆地的关键构造变革时期，建立了盆地演化的时-空框架。研究表明，鄂尔多斯盆地由下至上发育10个区域不整合面，分别为长城系、蓟县系、震旦系、寒武系、奥陶系、石炭系、三叠系、侏罗系、白垩系和第四系底界不整合面；盆地发育中元古界、寒武系-奥陶系、上石炭统-三叠系、侏罗系、下白垩统和新生界6个构造-地层层序。鄂尔多斯盆地的形成与演化受控于周缘板块构造作用，经历了中元古代早-中期大陆裂解、寒武纪-中奥陶世被动大陆边缘、晚奥陶世主动大陆边缘形成与碰撞造山、晚石炭世-二叠纪末期周缘裂解、中生代早期大型陆内坳陷、中生代中-晚期陆内前陆盆地和新生代周缘断陷等演化过程。鄂尔多斯盆地岩石圈深部的构造作用相对活跃，盆地内部发育中奥陶世、中-晚三叠世、早白垩世与晚中新世4期中酸性、中基性火山活动，其中，早白垩世晚期的火山活动强烈。结合周缘板块构造事件、盆内岩浆活动和盆地沉降-隆升过程分析，鄂尔多斯盆地经历了新元古代、晚奥陶世、中-晚三叠世、晚侏罗世-早白垩世、新生代5个关键构造变革期，这些构造变革期控制了盆地的构造演化和地质结构，对鄂尔多斯盆地的油气分布产生了深远影响。

Ordos Basin is a typical intracratonic basin, rich in mineral resources such as oil and gas, coal, salt, and uranium. Studying the periods, sequences and attributes of tectonic movement of the basin will not only lay the foundation for revealing the origin and evolution process of the craton basin, but also provide a basis for exploring the internal occurrence mechanism of the multiple energy and mineral resources. Based on high-resolution reflection seismic profile and deep-well data in recent years, in combination with the analysis of peripheral geological outcrops, this paper establishes a spatio-temporal framework of basin evolution by determining the key tectonic evolution periods of Ordos Basin. Studies have shown that there are 10 regional unconformities developed from bottom to top in the Ordos Basin, namely the basal unconformities in the Changchengnian, the Jixianian, the Sinian, the Cambrian, the Ordovician, the Carboniferous, the Triassic, the Jurassic, the Cretaceous and the Quaternary. Six tectono-stratigraphic sequences developed in the Mesoproterozoic, the Cambrian to Ordovician, the Upper Carboniferous to Triassic, the Jurassic, the Lower Cretaceous and the Cenozoic in the basin. The formation and evolution of Ordos Basin was controlled by the tectonization of the peripheral plates. It experienced the continental breakup in the early and middle period of the Mesoproterozoic, the development of passive continental margin during the Cambrian to the Middle Ordovician, the formation of active continental margin and collision orogeny in the Late Ordovician, the periphery breakup during the Late Carboniferous to the end of the Permian, the development of large-scale intracontinental depressions during the Early Mesozoic and intracontinental foreland basins during the Middle to Late Mesozoic, and peripheral fault depressions during the Cenozoic and other evolution processes. Tectonism in the deep lithosphere of Ordos Basin is relatively active. The basin is subjected to four periods of intermediate-acid or mafic-intermediate volcanic activities in the Middle Ordovician, the Middle and Late Triassic, the Early Cretaceous, and the Late Miocene, especially much extensive in the late period of the Early Cretaceous. Further, through analyzing the tectonic events of peripheral plates, intrabasin magmatic activity and basin subsidence-uplifting process, it is believed that Ordos Basin has experienced five key tectonic modification periods of the Neoproterozoic, the Late Ordovician, the Middle to Late Triassic, the Late Jurassic to Early Cretaceous, and the Cenozoic. These tectonic modification periods control the tectonic evolution and geological architecture of the basin, and have a profound impact on the distribution of oil and gas in Ordos Basin.

基于最新钻井与地震资料，对鄂尔多斯盆地乌审旗古隆起的分布进行刻画，同时采用Bischke曲线、平衡剖面方法分析其形成演化。结果表明，乌审旗古隆起为加里东早期形成的挤压型古隆起，平面呈南北向展布的椭圆状，长轴约194 km，短轴近东西向，长55~94 km，核部寒武系被剥蚀的厚度与面积分别为170~196 m和11 298 km²；利用年代地层格架剖面分析古隆起主体形成时间为怀远运动时期；中—晚寒武世为乌审旗隆起雏形期，晚寒武世末期隆起显著发育后被剥蚀，至奥陶纪马家沟组马三段沉积期隆起发生继承性活动，隆起面积减小，马四段沉积期—石炭系沉积前古隆起区地层发生非均一性抬升并遭受剥蚀，石炭纪及其之后进入埋藏保存的稳定期。乌审旗古隆起是在基底与构造薄弱带之上形成的，并受南部、北部的非共轴挤压以及盆内隆起传递的应力影响，发育成形态不规则的挤压型古隆起，该古隆起对沉积储集层和油气聚集具有一定控制作用。