Space-Time Coordinate of the Evolution and Reformation and Mineralization Response in Ordos Basin
Space-Time Coordinate of the Evolution and Reformation and Mineralization Response in Ordos Basin
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发表时间：
2006
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通讯作者：
Wang Jianqiang
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作者：
Wang Jianqiang
鄂尔多斯盆地发育于中晚三叠世-早白垩世，晚白垩世以来经历了改造。它主要具有克拉通内性质，是一个多期不同改造的残留盆地。鄂尔多斯盆地也是一个叠置在早、晚古生代盆地之上的多期叠合盆地。因此，多能源矿产资源十分丰富，石油、煤、铀三大能源矿产资源在同一盆地内。本文根据鄂尔多斯盆地及周边地区主要地质构造特征和地质事件，结合盆地各区裂变径迹年龄的综合研究，认为盆地发育过程中至少存在四个明显的构造波动阶段，盆地的演化和沉积也存在四个阶段。中-晚三叠世和早-中侏罗世富县期和延安期是两个最繁荣的阶段，这一时期湖泊广阔，盆地沉积广泛，面积是现今的两倍多，主要含油气层和含煤层发育。早侏罗世区域性抬升波动，强烈的不均匀切割侵蚀，导致延长组上部地貌的沉积中断和发育，从而划分了这两个阶段。延安晚期隆升波动较弱，沉积中断和剥蚀持续时间较短。之后盆地沉降，进入中侏罗世直罗-安定期的第三演化阶段，盆地内沉积范围仍较广，湖泊面积缩小。晚侏罗世盆地西缘发生强烈的构造运动，发育逆冲推覆带，西缘东侧前缘不同深度的砾岩存款，盆地中东部发生剥蚀改革。构造运动使黄河西部地区形成了东隆西陷的区域性构造格局。早白垩世，盆地西缘冲断带和盆地南北两侧的侧凸上，广泛的沉积物不整合超覆。鄂尔多斯盆地整体抬升消失，进入后期改造期。前三个阶段沉积中心位于延安市附近或东部，存款中心位于盆地西部近物源处。这两个中心在不同的阶段在空间上是不同的。直到早古生代，沉积中心和聚集中心的位置基本一致，均位于盆地西部的中南部。鄂尔多斯盆地晚白垩世以来的晚改造期发生了六次重大地质事件。(1)盆地主体的持续、阶段性、差异性隆升，造成了强烈的不均匀剥蚀，如东部黄河附近中生代最大剥蚀深度可达2000 m。(2)这一隆升形成了两期或三期的区域性侵蚀夷平面，其年龄分别为E3 - 1_2、E3和N2_1。(3)鄂尔多斯地块边部沉降，周缘断陷盆地相继形成，形成深度较大的存款。(4)区域性的东隆西陷运动持续了2个多月，但在此期间发生了逆转，即东部沉降依次为广泛存款的红粘土和六边山、鄂尔多斯地块西缘和盆地西部隆起。反转事件体现了中国西部区域构造运动的重要影响。(5)风成红粘土和黄土开始广泛沉积的时间分别为8 Ma BP和2.5Ma BP。红土半高原、黄土高原、黄土高原地表依次发育。(6)黄河水系发育，外流侵蚀围岩.根据上述重大地质事件和动力学环境的演化，将鄂尔多斯盆地晚白垩世以来划分为晚白垩世-古新世、始新世-渐新世、早中新世-中中新世、晚中新世-上新世和第四纪5个演化阶段。这些地质事件的发生和构造变动与周边构造域特别是我国东西部主要构造运动的复合性、反复性、时变性和强弱性密切相关。这些活动和改造极大地改变了中生代原型盆地的地貌，多种能源的发生、形成和重置的主要时期和阶段与鄂尔多斯盆地中、新生代的演化和改造有着明显的回溯和解耦关系。盆地演化晚期及以后的整体差异性隆升和区域性剥蚀对鄂尔多斯盆地多金属矿床的形成、分布及其相互作用具有重要影响。
Ordos basin has developed during middle—late Triassic and early Cretaceous and has been reformed since late Cretaceous. It mainly possesses the characters of intra-craton and is a residual basin with multi-stage and different reformation. Ordos basin also belongs to multi-superimposed basin which overlapped on the early and late Paleozoic basins. Therefore, Multi-energy mineral deposits are abundant and petroleum, coal and uranium are beared in the same basin. According to the the main geological structure features and geological events in ordos baisn and peripheral areas, together with the comprehensional research of the fission track ages in various district of the basin, the paper concludes that there exists four evident stages of structural fluctuation at least during basin development and also four stages of evolution and sedimentation in the basin. middle—late Triassic and early—middle Jurassic Fuxian and Yan'an stage is the two most prosperous stages during which the lake is broad and basin deposits extensively with an area over two times of that of present, the main oil and coal bearing strata develop. The two stages are divided by the regional early Jurassic uplift fluctuation, which causes interruption in deposition and development of the roughness of relief on the upper part of the Yanchang formation by reason of forceful and uneven cutting erosion. The uplift fluctuation is weak and the depositional interruption and erosion continuous time is short at the evening of Yan'an stage. Then basin subsides and enters the third evolution stage of middle Jurassic Zhiluo—Anding stage in which sedimentary range is still broad and the lake area is minish in the basin. There happens strongly structural movement and developed the thrust-nappe belt in western margin of the basin in late Jurassic during which the different depth of conglomerate deposit in the foredeep part in the east side of the western margin, erosion reform occurs in the middle and east of the basin. The structural movement causes the form of structure framework of regional east uplift and west subside in the west area of Yellow river. Broad sediments unconformablely overlap on the west margin thrust belt and sideral uplift of the basin north and south at the early Cretaceous stage. Ordos basin uplifts wholly to disappear and enters the late reformation period. In the first three stages, the depocenters lie near or to the east of Yan'an city, while deposit center in the west of the basin near provenance. The two centers differs in space in different stage. Until early Cretacious, the location of sedimentary depocenters and accumulation center is nearly same which is on the middle-south part of the west of the basin. There happen six major geological events in Ordos basin in late reformation period since late Cretaceous. (1) The main part of the basin uplifts continuously, episodically and differently, which causes the strong and uneven erosion, for example, the max erosion depth in Mesozoic can be two thousand meters near Yellow river on the east. (2) This uplift forms two or three stages of regional erosion-planation surfaces with ages of E 3-1__2,E_3 and N2_1. (3) The side of Ordos block subsides and the peripheral faulted basins form successively to deposit with heavy depth. (4) The regional east uplift and west subside movement continuing two bill years has been reversed which means the east subsides to widely deposit red clay and Liupianhshan, western margin of Ordos block and west part of basin uplift successively. The reverse event embodies the important influence of the regional structural movement of the west of China. (5) Aeolian red clay and loess begin to sediment broadly in 8Ma BPand 2.5Ma BP, respectively. Also the red mud semi-plateau, loess plateau and loess plateau surface develop successively. (6) Drainage system of Yellow river grows and fluid outside to erode the side rock. According to the above major geological events and the evolution of dynamics environment, five evolution stages is divided since late Cretaceous in Ordos basin which are late Cretaceous to Paleocene, Eocene to Oligocene, early—middle Miocene, late Miocene to Pliocene and Quaternary. The happening of these geological events and structural fluctuation are closely related with the compound, superimpose, change with time and strong-weak of major structural movement of peripheral structural domain especially that of the east and west of China. These activity and reformation change the Mesozoic prototype basin topography greatly.The main times and stages of the occurrence and formation and reset of miltiple energy resources have evident recall and decoupling relations with those of the Mesozoic and Cenozoic evolution and reformation in Ordos basin. The whole different uplift and regional erosion in and after the late of basin evolution own the important influence to the formation and distribution of the milti-mineral deposits and the coaction among them in Ordos basin.