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Unravelling the sources of carbon emissions at the onset of Oceanic Anoxic Event (OAE) 1a
被引:34
|作者:
Adloff, Markus
[1
]
Greene, Sarah E.
[2
]
Parkinson, Ian J.
[3
]
Naafs, B. David A.
[3
,4
]
Preston, Will
[3
]
Ridgwell, Andy
[1
,5
]
Lunt, Dan J.
[1
]
Castro Jimenez, Jose Manuel
[6
]
Monteiro, Fanny M.
[1
]
机构:
[1] Univ Bristol, Sch Geog Sci, Univ Rd, Bristol BS8 1SS, Avon, England
[2] Univ Birmingham, Sch Geog Earth & Environm Sci, Birmingham B15 2TT, W Midlands, England
[3] Univ Bristol, Sch Earth Sci, Queens Rd, Bristol BS8 1RJ, Avon, England
[4] Univ Bristol, Sch Chem, Cantocks Close, Bristol BS8 1TS, Avon, England
[5] Univ Calif Riverside, Dept Earth Sci, 900 Univ Ave, Riverside, CA 92521 USA
[6] Univ Jaen, Dept Geol, CEACTierra, Campus Lagunillas S-N, Jaen 23071, Spain
基金:
欧洲研究理事会;
关键词:
Aptian;
data assimilation;
carbon source;
osmium isotopes;
volcanism;
ISOTOPE STRATIGRAPHY;
SEDIMENTARY;
VOLCANISM;
RELEASE;
GREENHOUSE;
PLATFORMS;
EVOLUTION;
MODEL;
D O I:
10.1016/j.epsl.2019.115947
中图分类号:
P3 [地球物理学];
P59 [地球化学];
学科分类号:
0708 ;
070902 ;
摘要:
The early Aptian Oceanic Anoxic Event (OAE) la represents a major perturbation of the Earth's climate system and in particular the carbon cycle, as evidenced by widespread preservation of organic matter in marine settings and a characteristic negative carbon isotopic excursion (CIE) at its onset, followed by a broad positive CIE. The contemporaneous emplacement of a large igneous province (LIP) is invoked as a trigger for OAE la (and OAEs in general), but this link and the ultimate source of the carbon perturbation at the onset of OAEs is still debated. In this study, we simultaneously assimilate an atmospheric pCO(2) reconstruction along with a delta C-13 record from the Spanish Cau section in an Earth system model to obtain a novel transient reconstruction of emission rates and identify the primary carbon-emitting sources across the negative CIE interval at the onset of OAE la. We reconstruct carbon emissions of 4,300-29,200 Pg from a mixture of carbon sources. This estimate is a lower bound, as contemporaneous organic carbon burial is not accounted for. Carbon was first released at slow rates from a C-13-depleted reservoir (e.g. thermo- and/or biogenic methane from sill intrusions). Towards the end of the negative CIE the rate of emissions increased and they became more C-13-enriched, likely from a dominantly volcanic source (e.g. LIPs). New osmium isotope (Os-187 /Os-188) measurements, from the same section as the pCO(2) reconstruction and delta C-13 data, reveal a shift to less radiogenic values coinciding with the change towards mantle-derived carbon emissions as indicated by our modelling results, lending further support to our interpretation. These results highlight that geologically triggered carbon emissions were likely driving the OAE onset. (C) 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
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