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A 30 Myr record of Late Triassic atmospheric pCO2 variation reflects a fundamental control of the carbon cycle by changes in continental weathering.

Morgan F. Schaller; James D. Wright; Dennis V. Kent

Title:
A 30 Myr record of Late Triassic atmospheric pCO2 variation reflects a fundamental control of the carbon cycle by changes in continental weathering.
Author(s):
Schaller, Morgan F.
Wright, James D.
Kent, Dennis V.
Date:
Type:
Articles
Department(s):
Lamont-Doherty Earth Observatory
Volume:
127
Persistent URL:
Book/Journal Title:
Geological Society of America Bulletin
Abstract:
We generate a detailed ∼30 Myr record of pCO2 spanning most of the Late Triassic (Carnian-Norian-Rhaetian) to earliest Jurassic (Hettangian), based on stable carbon isotope ratios of soil carbonate and preserved organic matter from paleosols in the eastern North American Newark rift basin. Atmospheric pCO2 was near 4500 ppm in the late Carnian, decreasing to below ∼2000 ppm by the late Rhaetian just before the earliest Jurassic eruption of the Central Atlantic Magmatic Province, which triggered measurable pulses of CO2 outgassing. These data are consistent with published modeling results using the GEOCLIM model, which predict a decrease in pCO2 over the Late Triassic as a result of the progressive increase in continental area subject to the intense weathering regime of the tropical humid belt due to Pangea’s northward motion. The finer-scale pCO2 changes we observe may be dependent on the lithology introduced to the tropics, such as the dip to ∼2000 ppm around 212 Ma and its rebound to ∼4000 ppm at 209 Ma, which can be accomplished by introducing a more weatherable subaerial basaltic terrain. These observations indicate that the consumption of CO2 by continental silicate weathering can force long-term changes in pCO2 comparable to those driven by presumed changes in mantle degassing.
Subject(s):
Paleoclimatology
Atmospheric chemistry
Publisher DOI:
https://doi.org/10.1130/B31107.1
Item views
169
Metadata:
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Suggested Citation:
Morgan F. Schaller, James D. Wright, Dennis V. Kent, , A 30 Myr record of Late Triassic atmospheric pCO2 variation reflects a fundamental control of the carbon cycle by changes in continental weathering., Columbia University Academic Commons, .

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