Atmospheric CO2 estimates based on Gondwanan (Indian) pedogenic carbonates reveal positive linkage with Mesozoic temperature variations
Palaeogeography, Palaeoclimatology, Palaeoecology
CO2 is an important greenhouse gas that is known to drive global climatic changes. Multiple studies tracking pCO2 changes throughout the Phanerozoic have highlighted the linkage between CO2 levels and the corresponding icehouse-greenhouse conditions. However, deviations from the above relationship due to inconsistencies in pCO2 estimation, as well as large time-steps in existing geochemical models and gaps in proxy data suggest that the paleo-pCO2 record is not always well-constrained. Here, we attempt to reconstruct atmospheric CO2 concentration for parts of the late Early and Middle Triassic and Early Cretaceous from several carbonate-forming paleosols of the Indian Gondwana. We measured the carbon isotopic composition of pedogenic carbonates (δ13Ccarb) and organic matter occluded within soil carbonates (δ13Corg) from Pachmarhi, Denwa, and Bagra Formation of the Satpura Basin (n = 60) to estimate CO2 using a pedogenic carbonate-based paleo-barometer. The late Early Triassic (Olenekian) shows low CO2 concentrations (562 ± 426 ppmV), which is followed by an increase (822 ± 523 ppmV) in the Middle Triassic (Anisian). The Early Cretaceous is found to have the highest average concentration (1517 ± 594 ppmV). Our pCO2 estimates are well correlated with the existing proxy record and geochemical models and suggest fluctuations in CO2 levels that are consistent with temperature variations previously estimated for the periods.
Roy, Sohom; Sanyal, Prasanta; Ghosh, Parthasarathi; Bhattacharya, S. K.; and Ajay, A., "Atmospheric CO2 estimates based on Gondwanan (Indian) pedogenic carbonates reveal positive linkage with Mesozoic temperature variations" (2021). Journal Articles. 1714.