Earth Science Frontiers ›› 2025, Vol. 32 ›› Issue (4): 497-509.DOI: 10.13745/j.esf.sf.2024.11.77

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Early Cretaceous wildfire events in NE China and implications on deep-time ecosystems

WANG Shuai1,2(), DONG Tao1, LI Yanan1,2, XU Xiaotao3, GAO Lianfeng1,2, ZHANG Zhenguo1,2   

  1. 1. College of Mining, Liaoning Technical University, Fuxin 123000, China
    2. Liaoning Key Laboratory of Green Development of Mineral Resources, Fuxin 123000, China
    3. General Prospecting Institute of China National Administration of Coal Geology, Beijing 100039, China
  • Received:2024-08-04 Revised:2024-11-29 Online:2025-07-25 Published:2025-08-04

Abstract:

The Early Cretaceous was marked by extensive wildfires across the globe. Wildfires, as an critical component of the global ecosystem, are increasingly recognized for their profound impact on deep-time ecosystems. Based on the wildfire records from the Early Cretaceous in NE China, as well as the global records on CO2, O2 concentrations and the evolution of vegetation, this study synthesizes the characteristics and influencing factors of wildfires and analyzes their implications on deep-time ecosystems during this period. The Early Cretaceous Albian in NE China exhibits an inertinite content of 24.17% (volume fraction), compared to a lower content of 18.68% (volume fraction) in the Aptian. Based on the relationship model between inertinite content and oxygen content, the estimated Albian oxygen concentration is 24.92% and Aptian oxygen concentration is 24.21%. Utilizing a relationship model that correlates inertinite reflectance with combustion temperature, the types of wildfires in the Early Cretaceous Albian and Aptian stages in NE China are classified as ground fires and surface fires. From the Aptian to the Albian stages, the types of wildfires are predominantly ground fires. During the early phase of the Early Cretaceous, angiosperms were characterized by their low stature, shorter life cycles, high vein density, and high photosynthetic rates, which better adapted them to the low-intensity wildfires during this period. Meanwhile, the frequent occurrence of wildfires in the Early Cretaceous promoted the wide spread of angiosperms, which in turn led to a reduction in the diversity of gymnosperms and ferns. Wildfires led to enhanced surface erosion and runoff, which facilitated the influx of large amounts of terrestrial organic matter and nutrients, such as nitrogen and phosphorus, into lakes or oceans. This influx caused eutrophication in lakes or oceans and promoted the proliferation of planktonic organisms. As substantial amounts of terrestrial organic matter and plankton sink in the water, they consumed dissolved oxygen, fostering the development of oxygen-deficient environments. This process contributed to the accumulation of organic-rich mudstones during the Early Cretaceous.

Key words: Northeast China, Early Cretaceous, inertinite, wildfire, ecosystem

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