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Geoscience ›› 2020, Vol. 34 ›› Issue (04): 769-783.DOI: 10.19657/j.geoscience.1000-8527.2020.04.13

• Petroleum Geology • Previous Articles     Next Articles

Color Origin of the Lower Triassic Liujiagou and Heshanggou Formations Red Beds in the Ordos Basin

TAN Cong1(), YU Bingsong2, YUAN Xuanjun1(), LIU Ce1, WANG Tongshan1, ZHU Xi3   

  1. 1. Research Institute of Petroleum Exploration & Development, Beijing 100083, China
    2. School of Earth Science and Resources, China University of Geosciences, Beijing 100083, China
    3. Liaoning Chemical Geology Exploration Institute, Jinzhou,Liaoning 121000, China
  • Received:2019-08-15 Revised:2019-12-13 Online:2020-08-31 Published:2020-09-03
  • Contact: YUAN Xuanjun

Abstract:

The Lower Triassic Liujiagou and Heshanggou formations (Fms.) of the Ordos Basin in China contain large-scale red sandstone-mudstone deposition. Due to their lack of fossils and marker beds, study of these strata is difficult and little research attention has been paid to them. In this study, the red beds of the Liujiagou and Heshanggou formations were studied by means of drill-core and outcrop observation, optical microscopy, scanning electron microscope (SEM), X-ray diffractometer (XRD) and whole-rock major-and trace-element analyses. In addition, comparison with other strata of different colors from around the red beds was performed. The XRD and SEM analyses show that the dominant clay minerals in the red beds are smectite±illite. Trace amounts of fine disseminated hematite on the smectite flakes of pore infill have given the red color to the rocks. Sedimentary facies and elemental geochemistry reveal that the red beds are the products of a hot arid climate and a strongly oxidizing environment. These red beds are of sedimentary origin. By comparing the red beds with the rocks of different colors, it is shown that the different colors of sedimentary rocks are due mainly to their mineral contents, which reflect the basinal tectonic evolution and changes in the climate and sedimentary environment.

Key words: Ordos Basin, Lower Triassic, red beds, color origin

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