Earth Science Frontiers ›› 2019, Vol. 26 ›› Issue (1): 44-58.DOI: 10.13745/j.esf.sf.2019.1.3

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Jurassic prototype basin restoration and hydrocarbon exploration prospect in the Qaidam Basin and its adjacent area

FENG Qiao,FU Suotang,ZHANG Xiaoli,CHEN Yan,WANG Liqun,ZHOU Fei,NI Jinlong   

  1. 1. College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266510, China
    2. Qinghai Oilfield Branch, PetroChina, Dunhuang 736202, China
    3. State Key Laboratory of Continental Dynamics, Geology Department, Northwest University, Xi’an 710069, China
    4. Evaluation and Detection Technology Laboratory of Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, China
  • Received:2018-10-20 Revised:2018-11-18 Online:2019-01-30 Published:2019-01-30
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Abstract: The Jurassic is one of the most important sources and reservoirs in the Qaidam Basin. In this report, we conducted a comprehensive study on field geology, profile measurement, seismic interpretation and microscopic structural features of the study area in the Qaidam Basin. The results indicate the study area experienced the Indo-Chinese tectonic movement of right thrust and strike-slip structure in the Late Triassic, stretch movement in the Early to Middle Jurassic, NW-SE compressive stress in the Early Cretaceous, and NS compressional stress in the Cenozoic since the Mesozoic. These tectonic events can be related to the Early Jurassic fault basin formed by the NE stretch stress field, the Middle to Late Jurassic depression basin by the thermal subsidence, and the Early Cretaceous NS compressional depression basin. Three types of sedimentary boundary developed in the Jurassic prototype basin: the unconformity boundary at the edge of the basin (Gentle or steep slope), the normal fault boundary within the sedimentary basin, and the reverse fault reconstruction boundary in the later period. And different existing basin boundary types have different effects on the restoration of the prototype basin. The Jurassic basin East Kunlun tectonic belt boundary has the ancient geographical pattern of “northern land and southern ocean”. Jurassic basin in the Qaidam region is mainly developed in the foreland depression of coastal orogenic and island arc belts as well as the Caledonian subduction collision zone on the northern margin, forming a relatively separate and independent basin group. The development of the Qaidam prototype basin is affected by the subduction of the Paleotethys Ocean northward and the left-lateral slip fault of Altyn tagh. The sedimentary center and range assumed the law of gradual migration to the northeast from Early to Late Jurassic. The sedimentary and subsidence centers of Early Jurassic basin are located mainly in the LenghuMahai area in western Qaidam Basin, and that of Middle and Late Jurassic basins are located in the DachaidanHuaitoutala and DelinhaWulan areas, respectively.

 

Key words: basin boundaries, facies distribution, prototypes, structural characteristics, Qaidam Basin

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