Records of volcanism and organic carbon isotopic composition (δ13Corg) linked to changes in atmospheric pCO2 and climate during the Pennsylvanian icehouse interval

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Authors

Colleges, School and Institutes

External organisations

  • China University of Mining and Technology
  • University of Mining and Technology
  • Research Institute of Petroleum Exploration and Development

Abstract

The late Paleozoic ice age (LPIA) during the Carboniferous and Permian (ca. 360–260 Ma) was vegetated Earth’s only recorded icehouse-to-greenhouse transition and provides a deep-time perspective for climate-glaciation-environment coevolution and future climate change. During the LPIA, changes in glacial-interglacial cycles have been closely linked to atmospheric pCO2. In this paper, we investigate the relationship between volcanism and glacial to interglacial climate cycles during the Pennsylvanian to earliest Cisuralian in the Liujiang Coalfield from the North China Plate (NCP). We use integrated data from Zircon U-Pb dating, Hg/TOC ratios and δ13Corg to recover temporal trends in volcanic intensity and relate these to fluctuations in the global carbon cycle and atmospheric pCO2. Four new radiometric dates from tuffaceous claystones provide a precision stratigraphic framework and constrain the succession to ∼322 to 301 Ma. Results date the Benxi Formation to the Bashkirian–Moscovian stages of the Carboniferous, and the Taiyuan Formation ranging from the Kasimovian stage of the Carboniferous to the Asselian stage of the Permian. Results from Hg/TOC ratios record four peaks of volcanic intensity from the Bashkirian to the Carboniferous-Permian (C-P) transition period, and two low ebbs during the early-middle Bashkirian and the early-middle Moscovian. Peaks in volcanic intensity coincide with the four negative excursions of δ13Corg and correlate with volcanism in the North China Plate and NW Europe, inferring volcanic drivers for the carbon isotope excursions and perturbations in the global carbon cycle. Periods of higher atmospheric pCO2 correlate to interglacial intervals, the two lower ebbs in pCO2 correlate with two positive isotope plateaus, while periods of lower atmospheric pCO2 and cooling correlate with glacial intervals C3 and C4 recognized from other sections globally. Results suggest volcanism to be a significant driver for late Pennsylvanian to earliest Cisuralian shifts in global climates from glacial to interglacial through greenhouse gas emissions and changes to the global carbon cycle. Our results represent an important contribution to the development of an accurate chronostratigraphy for the continental facies of the NCP during the Pennsylvanian and earliest Permian, enabling correlation of volcanic and climate events including glacial and interglacial cycles.

Details

Original languageEnglish
Article number120168
JournalChemical Geology
Volume570
Early online date8 Mar 2021
Publication statusPublished - 5 Jun 2021

Keywords

  • Carboniferous, North China Plate, organic carbon isotope composition, paleoclimate, zircon dating

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