Earth Science Frontiers ›› 2021, Vol. 28 ›› Issue (2): 391-411.DOI: 10.13745/j.esf.sf.2020.6.29

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Preliminary analysis on the paleogeography and paleoenvironment in the eastern Yanliao area during the Jurassic-Cretaceous tectonic transition

LI Xiaobo1,2,3(), ZHANG Yan1, TONG Yabo4   

  1. 1. College of Earth Sciences, Dinosaur Evolution Research Center, Jilin University, Changchun 130061, China
    2. Department of Biology, University of Toronto Mississauga, Ontario L5L 1C6, Canada
    3. Key-Lab for Evolution of Past Life and Environment in Northeast Asia, Ministry of Education, Changchun 130026, China
    4. Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China
  • Received:2019-01-07 Revised:2019-07-24 Online:2021-03-25 Published:2021-04-03

Abstract:

During the transit period from the Middle and Late Jurassic to early Early Cretaceous, the tectonic pattern and paleogeography overturned in eastern China. This paper discusses some issues on the paleogeography and paleoenvironment in the eastern Yanliao area through this period. The preliminary results show that the aggravate plate convergence at the continental margin of eastern Asian from the Middle Jurassic induced the crustal thickening and tectonic uplifting in the region. With the continuance of the subduction of the Paleo-Pacific (Isanagi) Plate, deep magma upwelled, crust thinned, and multiphasic rifts developed, while the East Asian ocean-continent connection zone underwent tectonic escape. These processes shaped the high mountain and other basin-wide paleo-landforms in the Yanliao area. During the early Early Cretaceous(137-131 Ma), an altitude difference—low in the west and high in the east—established along the extension line through the Nenjiang-Balihan Fault and the Kharatsin Metamorphic Core Complex. In the comparatively descending western part, the strata of the Northern Hebei-Great Xingan Mountain volcano-graben belt yielded the fossils of the early assemblage of the Jehol Biota, while the Western Liaoning-Songliao area rose to tectonic upland. As the rifting area expanded during the 130-110 Ma, the middle and late-phase assemblages of the Jehol Biota extended to the surrounding areas. The paleoclimate of the Jehol Biota was temperate continental, mostly arid and cold, thus not inconsistent with the notion that the paleoclimate was affected potentially by the environment of the Mesozoic East China Plateau. The global paleoclimatic evolution and regional paleogeographical condition jointly caused the subartic climate trend in the Yanliao area from the Late Jurassic to Early Cretaceous, and further affected the evolution of the paleo-ecosystem from the Middle-Late Jurassic Yanliao Biota to the Early Cretaceous Jehol Biota.

Key words: Western Liaoning, Yanshanian Movement, Yanliao Biota, Jehol Biota, intracontinental orogeny

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