Oil & Gas Geology ›› 2017, Vol. 38 ›› Issue (2): 281-291.doi: 10.11743/ogg20170208

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New understanding of the Cambrian palaeotectonic and lithofacies palaeogeography in the Ordos Craton Basin

Zhang Chunlin1, Zhang Fudong1, Zhu Qiuying1,2, Liu Ruie1,2, Xin Ming3   

  1. 1. Langfang Branch of PetroChina Research Institute of Petroleum Exploration and Development, Langfang, Hebei 065007, China;
    2. Key Laboratory of Gas Reservoir Formation and Development, CNPC, Langfang, Hebei 065007, China;
    3. No.1 Oil Production Plant, PetroChina Qinghai Oilfield Company, Dunhuang, Gansu 816400, China
  • Received:2016-02-18 Revised:2016-02-17 Online:2017-04-28 Published:2017-05-04

Abstract: A study was carried out on the Cambiran paleotectonic and lithofacies paleogeography of Ordos craton basin based on relevant outcrops,drilling and seismic data.Isopach showed that the Cambrian sedimentary framework inherited the Meso-Neoproterozoic sedimentary framework and can be described as "three troughs,two lands and one depression".Based on this understanding and guided by carbonates sedimentology,we divided the Cambrian into four sedimentary systems:the shoreland,the open carbonate platform,the shelf slope and the trough;and compiled 5 lithofacies paleogeographic maps.The overall lithofacies paleogeographic outlook may be described as the following:in the direction from ancient land to sea successively occurring shoreland,platform with depression,ramp and trough.The Ordos area had experienced a complete transgression-regression process in the Cambrian.A massive ancient land still existed in the Early Cambrian with only a set of shoreland and an open platform sedimentary facies around southwestern margin.During the Middle Cambrian,ancient land shrunk and was segmented into three isolated ancient lands along with transgression of sea.After the Luliang ancient land finally disappeared in Zhangxia Stage,the central and eastern part was featured by open platforms and the southwestern part contained mainly shelf slopes and through.During the Later Cambrian,with the beginning of regression of sea,the ancient land wound southnorth-ward in central Ordos area.

Key words: lithofacies palaeogeography, aulacogen, paleotectonic, Cambrian, craton, Ordos Basin

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