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Title: Numerical evaluation of mechanisms driving Early Jurassic changes in global carbon cycling

Abstract

The Early Jurassic (early Toarcian, ca. 183 Ma) carbon cycle perturbation is characterized by aabout -5 parts per thousand {delta} {sup 13}C excursion in the exogenic carbon reservoirs, a 1000 ppm rise in atmospheric CO{sub 2}, and a 6-7 degrees warming. Two proposed explanations for this presumed global carbon cycle perturbation are the liberation of massive amounts of isotopically light CH4 from (1) Gondwanan coals by heating during the intrusive eruption of the Karoo-Ferrar large igneous province (LIP) or (2) the thermal dissociation of gas hydrates. Carbon cycle modeling indicates that the release of CH4 from Gondwanan coals synchronous with the eruption of the Karoo-Ferrar LIP fails to reproduce the magnitude or timing of the CO{sub 2} and {delta} {sup 13}C excursions. However, sensitivity analyses constrained by a marine cyclostratigraphically dated {delta}{sup 13}C record indicate that both features of geologic record can be explained with the huge input of about 15,340-24,750 Gt C over about 220 k.y., a result possibly pointing to the involvement of hydrothermal vent complexes in the Karoo Basin. The simulated release of > 6000 Gt C from gas hydrates also reproduces aspects of the early Toarcian rock record, but the large mass involved raises fundamental questionsmore » about its formation, storage, and release.« less

Authors:
;  [1]
  1. University of Sheffield, Sheffield (United Kingdom)
Publication Date:
OSTI Identifier:
20947294
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geology; Journal Volume: 35; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; JURASSIC PERIOD; CARBON DIOXIDE; EARTH ATMOSPHERE; ORIGIN; CARBON CYCLE; CARBON 13; GAS HYDRATES; COAL DEPOSITS; GONDWANA; IGNEOUS ROCKS; METHANE; GREENHOUSE EFFECT

Citation Formats

Beerling, D.J., and Brentnall, S.J. Numerical evaluation of mechanisms driving Early Jurassic changes in global carbon cycling. United States: N. p., 2007. Web. doi:10.1130/G23416A.1.
Beerling, D.J., & Brentnall, S.J. Numerical evaluation of mechanisms driving Early Jurassic changes in global carbon cycling. United States. doi:10.1130/G23416A.1.
Beerling, D.J., and Brentnall, S.J. Thu . "Numerical evaluation of mechanisms driving Early Jurassic changes in global carbon cycling". United States. doi:10.1130/G23416A.1.
@article{osti_20947294,
title = {Numerical evaluation of mechanisms driving Early Jurassic changes in global carbon cycling},
author = {Beerling, D.J. and Brentnall, S.J.},
abstractNote = {The Early Jurassic (early Toarcian, ca. 183 Ma) carbon cycle perturbation is characterized by aabout -5 parts per thousand {delta} {sup 13}C excursion in the exogenic carbon reservoirs, a 1000 ppm rise in atmospheric CO{sub 2}, and a 6-7 degrees warming. Two proposed explanations for this presumed global carbon cycle perturbation are the liberation of massive amounts of isotopically light CH4 from (1) Gondwanan coals by heating during the intrusive eruption of the Karoo-Ferrar large igneous province (LIP) or (2) the thermal dissociation of gas hydrates. Carbon cycle modeling indicates that the release of CH4 from Gondwanan coals synchronous with the eruption of the Karoo-Ferrar LIP fails to reproduce the magnitude or timing of the CO{sub 2} and {delta} {sup 13}C excursions. However, sensitivity analyses constrained by a marine cyclostratigraphically dated {delta}{sup 13}C record indicate that both features of geologic record can be explained with the huge input of about 15,340-24,750 Gt C over about 220 k.y., a result possibly pointing to the involvement of hydrothermal vent complexes in the Karoo Basin. The simulated release of > 6000 Gt C from gas hydrates also reproduces aspects of the early Toarcian rock record, but the large mass involved raises fundamental questions about its formation, storage, and release.},
doi = {10.1130/G23416A.1},
journal = {Geology},
number = 3,
volume = 35,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
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