摘要： 基于多年来对盆地周缘大量的野外露头勘察以及盆地内部分钻井岩心描述,主要从沉积环境、岩石类型、岩石沉积结构及构造、古生物化石等众多方面,对鄂尔多斯盆地的沉积体系类型和特征以及古地理环境的整体演化进行了全面、系统的研究。结果表明,中新元古代长城期至蓟县期,主要由陆相—滨浅海相沉积转变为碳酸盐潮坪沉积。早古生代辛集期至朱砂洞期,主要由盆地西南缘的环古陆砂坪沉积演变为云坪沉积;馒头期至三山子期,主要发育开阔海台地沉积,但范围变化相对较大;冶里期至亮甲山期,主要由盆地东南缘的环古陆泥云坪沉积演变为云坪沉积;马家沟期大规模海侵形成了广阔的浅水陆表海沉积;峰峰期以台地前缘斜坡和大陆斜坡海槽沉积为主;平凉期盆地南部出现了台地边缘浅滩;背锅山期仅在盆地西南角分布开阔台地及台前斜坡沉积。晚古生代—中三叠世本溪期为填平补齐时期,发育潮坪—潟湖—障壁岛—浅海陆棚沉积:太原期,盆地东部浅海陆棚沉积范围减小;山西期至纸坊期,盆地均主要以三角洲沉积和浅湖沉积为主,但各期沉积范围均有变化。晚三叠世延长期—白垩纪,主要为湖泊沉积并伴有曲流河、辫状河以及三角洲等沉积体系:延长期长7油层组沉积时期湖侵范围最大;富县期至安定期,以曲流河、三角洲和浅湖沉积为主,但浅湖沉积范围在不同时期有明显变化,安定期出现深湖沉积;芬芳河期主要为冲积扇沉积。白垩纪盆内沉积范围变小,主要发育沙漠沉积和浅湖沉积。

关键词: 鄂尔多斯盆地, 沉积体系, 古地理, 中新元古代, 早古生代, 晚古生代-中三叠世, 晚三叠世-白垩纪

Abstract: The types and characteristics of depositional systems and the evolution of the palaeogeographic environment of the Ordos Basin were studied comprehensively and systematically,based on many years of field surveys on the periphery outcrop of the basin and descriptions of some cores in the basin. Investigations of depositional environments,rock types,sedimentary structures,and palaeontological fossils in the basin reveal that the depositional system transformed from the continental-nearshore to the carbonate tidal flat environment during the Mesoproterozoic-Neoproterozoic Changcheng to Jixian period. During the Early Paleozoic Xinji to the Zhushadong period,the depositional system around the Ordos palaeo-continent in the western and southern margin of the basin evolved from the sand flat to dolomite flat environment. During the Mantou to the Sanshanzi period,sedimentation on the open sea platform dominated,but the area of the depocenters greatly varied. From the Yeli to the Liangjiashan period,the depositional system in the eastern and southern margins of the basin evolved from the argillaceous dolomite flat to the dolomite flat environment. The large-scale transgression in the Majiagou period resulted in extensive shallow-water epicontinental deposits. The deposition system in the Fengfeng period was dominated by the platform margin slope and continental slope trough deposits. During the Pingliang period, shoal deposits occurred on the platform margin in the southern part of basin. During the Beiguoshan period,the dominant open-platform and the fore-platform slope deposits were only distributed in the southwestern corner of the basin. The basin in the Late Paleozoic-Middle Triassic Benxi period was characterized by a filling process and the deposition in the tidal flat-lagoon-barrier island-shallow sea shelf. During the Taiyuan period,the range of the shallow sea shelf sedimentation in the eastern part reduced. During the Shanxi to the Zhifang period,the depositional systems were dominated by the delta and shallow lake deposits,with the depocenters considerably varied in different periods. In the Late Triassic Yanchang period-Cretaceous,lake deposits,as well as deposits of meandering rivers,braided rivers,and deltas dominated. The maximum lake transgression occurred in the Chang 7 period. During the Fuxian to the Anding period,the meandering river,delta,and shallow lakes deposits were developed. The depocenter of the shallow lakes varied significantly in different periods,and the deep lake sediments occurred in the Anding period. During the Fenfanghe period,the alluvial fan deposits dominated. In the Cretaceous,the depocenter became smaller and is characterized by dominant desert and shallow lake deposits.

Key words: sedimentary system, palaeogeography, Mesoproterozoic-Neoproterozoic, Early Paleozoic, Late Paleozoic-Middle Triassic, Late Triassic-Cretaceous, Ordos Basin

中图分类号: 

• P531