Abstract
Initial breakup of Pangaea and opening of the Central Atlantic Ocean during the Early Jurassic resulted in widespread volcanism and was accompanied by significant changes in atmospheric composition, climate and environment of the Earth's surface system. Although profound changes in global geochemical cycles, palaeoclimate, and palaeoenvironments during the early part of the Toarcian Stage have been extensively studied and attributed to the emplacement of the Karro-Ferrar Large Igneous Province (LIP), similar changes in other parts of the Early Jurassic are less well known, especially in terrestrial settings. We studied Pliensbachian aged terrestrial strata from the Dameigou section in the Qaidam Basin of the Qinghai-Tibet Plateau to elucidate climate and environmental changes and their potential driving mechanisms. Three significant climate and environment perturbations were recognized by high-resolution mineralogical and geochemical analyses, with each characterized by peaks in kaolinite composition that indicate relatively warm and humid climates. Each kaolinite peak is accompanied by proxy evidence that indicates anoxic redox conditions, high paleoproductivity, and strong continental weathering prevailed, and coincides with negative carbon isotope excursions and peaks in Hg/TOC ratios that record three episodes of concurrent volcanism. The three episodes of volcanism are correlated with global events and suggest volcanism as the driving mechanism for major global climate and environment perturbations during the Pliensbachian. Each interval of volcanism released massive quantities of greenhouse gases and Hg into the atmosphere, leading to negative carbon isotope excursions and mercury anomalies in sedimentary strata. Global climatic warming induced by volcanism resulted in an enhanced hydrological cycle and can be correlated with more humid climatic conditions, intensified continental weathering and organic matter burial, lake expansion, and eutrophication. Such changes have important negative feedback on the global carbon cycle by increasing consumption of CO2 in lacustrine settings, which in the late Pliensbachian led to the restoration of similar climates and environments that occurred pre-volcanism in the study area.
Original language | English |
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Article number | 103919 |
Number of pages | 15 |
Journal | Global and Planetary Change |
Volume | 216 |
Early online date | 16 Aug 2022 |
DOIs | |
Publication status | Published - Sept 2022 |
Bibliographical note
Funding Information:We thank Maoyan Zhu (Nanjing Institute of Geology and Palaeontology) and two anonymous reviewers for feedback on the manuscript. We are grateful to Suping Peng and Shifeng Dai (China University of Mining and Technology Beijing) for comments on earlier versions of the manuscript. This research was supported by the National Key Research and Development Program of China (Award 2021YFC2902000 ), the Natural Environment Research Council’s Biosphere Evolution, Transition and Resilience (BETR) Program (Grant NE/P0137224/1 ), National Natural Science Foundation of China (Grants 41772161 , 42172196, and 41472131 ), and the National Science and Technology Major Project (Award 2017ZX05009-002 ).
Publisher Copyright:
© 2022
Keywords
- Early Jurassic
- Large Igneous Province volcanism
- Qaidam Basin
- Qinghai-Tibet Plateau
- Terrestrial mudstones
ASJC Scopus subject areas
- Oceanography
- Global and Planetary Change