Welcome to Geological Journal of China Universities ! Today is
Share:

Acta Metallurgica Sinica ›› 2020, Vol. 26 ›› Issue (6): 704-711.DOI: 10.16108/j.issn1006-7493.2019085

Previous Articles     Next Articles

Paleoenvironment Changes Inferred from the Analysis of Organic Elements and Carbon Isotope Characteristics of Jurassic Argillaceous Rocks in the Dameigou, North Qaidam Basin

LI Wenshuai 1,ZHANG Xiaoli 2,FENG Qiao 1* , JIAO Ke 1,CHEN Yan 3,ZOU Kaizhen 3,CUI Han 3   

  1. 1. College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China;
    2. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, China;
    3. Research Institute of Exploration and Development, Petrochina Qinghai Oilfield Company, Dunhuang 736202, China
  • Online:2020-12-20 Published:2021-01-05

Abstract: The Jurassic strata in the Dameigou area of the North Qaidam Basin recorded the evolution of paleoenvironment in the Northwest. In this paper, the organic geochemical analysis of the Dameigou section is performed to reconstruct the environmental evolution of the Jurassic in the Dameigou area. The analysis reveals that the H/C ratio shows a good negative correlation with the C/N ratio and δ 13C. The C/N ratios and δ 13C values decrease gradually and the H/C ratio gradually increases during the Early Jurassic. In the Middle Jurassic, the C/N ratio and δ 13C remained stable in the early stage and the latter was sharply negative, while the H/C ratio was reversed. During the Late Jurassic, the C/N ratio and δ 13C remained largely unchanged and the H/C ratio was stable in the high value range. The C/N ratio of organic elements in the early-middle Jurassic is greater than 15, indicating that organic matter is mainly from terrestrial higher plants. The paleoclimate of the Dameigou section is characterized by two cycles: in the Early Jurassic Xiaomeigou Formation, the paleoclimate was  haracterized by warm-humidity-dry heat and the paleoclimate evolved from warm wet to dry hot in the late Middle Jurassic.

Key words: Dameigou, organic carbon isotope δ13C, C/N, H/C, Paleoclimate

CLC Number: