Article (Scientific journals)
Enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands: a sink for atmospheric CO2
Wan, Shiming; Clift, Peter D.; Zhao, Debo et al.
2017In Geochimica et Cosmochimica Acta, 200, p. 123-144
Peer Reviewed verified by ORBi
 

Files


Full Text
Wan-etal.123-144.pdf
Publisher postprint (7.2 MB)
Main text
Request a copy
Annexes
Wan-etal.123-144_mmc1.xls
Publisher postprint (362.5 kB)
Supplementary Table 1
Request a copy
Wan-etal.123-144_mmc2.xls
Publisher postprint (166.4 kB)
Supplementary Table 2
Request a copy
Wan-etal.123-144_mmc3.xls
Publisher postprint (111.62 kB)
Supplementary Table 3
Request a copy

All documents in ORBi are protected by a user license.

Send to



Details



Keywords :
Chemical weathering; Climate change; Carbon cycle; Glacial-interglacial; South China Sea; Tropical continental shelf
Abstract :
[en] Atmospheric CO2 and global climate are closely coupled. Since 800 ka CO2 concentrations have been up to 50% higher during interglacial compared to glacial periods. Because of its dependence on temperature, humidity, and erosion rates, chemical weathering of exposed silicate minerals was suggested to have dampened these cyclic variations of atmospheric composition. Cooler and drier conditions and lower non-glacial erosion rates suppressed in situ chemical weathering rates during glacial periods. However, using systematic variations in major element geochemistry, Sr-Nd isotopes and clay mineral records from Ocean Drilling Program Sites 1143 and 1144 in the South China Sea spanning the last 1.1 Ma, we show that sediment deposited during glacial periods was more weathered than sediment delivered during interglacials. We attribute this to subaerial exposure and weathering of unconsolidated shelf sediments during glacial sealevel lowstands. Our estimates suggest that enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands can account for ~9% of the carbon dioxide removed from the atmosphere during the glacial and thus represent a significant part of the observed glacial-interglacial variation of ~80 ppmv. As a result, if similar magnitudes can be identified in other tropical shelf-slope systems, the effects of increased sediment exposure and subsequent silicate weathering during lowstands could have potentially enhanced the drawdown of atmospheric CO2 during cold stages of the Quaternary. This in turn would have caused an intensification of glacial cycles. We attribute this to subaerial exposure and weathering of unconsolidated shelf sediments during glacial sealevel lowstands. Our estimates suggest that enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands can account for ~9% of the carbon dioxide removed from the atmosphere during the glacial and thus represent a significant part of the observed glacial-interglacial variation of ~80 ppmv. As a result, if similar magnitudes can be identified in other tropical shelf-slope systems, the effects of increased sediment exposure and subsequent silicate weathering during lowstands could have potentially enhanced the drawdown of atmospheric CO2 during cold stages of the Quaternary. This in turn would have caused an intensification of glacial cycles.
Research center :
SPHERES - ULiège
Disciplines :
Earth sciences & physical geography
Author, co-author :
Wan, Shiming
Clift, Peter D.
Zhao, Debo
Hovius, Niels
Munhoven, Guy ;  Université de Liège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
France-Lanord, Christian
Wang, Yinxi
Xiong, Zhifang
Huang, Jie
Yu, Zhaojie
Zhang, Jin
Ma, Wentao
Zhang, Guoliang
Li, Anchun
Li, Tiegang
More authors (5 more) Less
Language :
English
Title :
Enhanced silicate weathering of tropical shelf sediments exposed during glacial lowstands: a sink for atmospheric CO2
Publication date :
2017
Journal title :
Geochimica et Cosmochimica Acta
ISSN :
0016-7037
eISSN :
1872-9533
Publisher :
Pergamon Press - An Imprint of Elsevier Science, Oxford, United Kingdom
Volume :
200
Pages :
123-144
Peer reviewed :
Peer Reviewed verified by ORBi
Funders :
F.R.S.-FNRS - Fonds de la Recherche Scientifique [BE]
Available on ORBi :
since 23 December 2016

Statistics


Number of views
122 (7 by ULiège)
Number of downloads
2 (1 by ULiège)

Scopus citations®
 
87
Scopus citations®
without self-citations
50
OpenCitations
 
68

Bibliography


Similar publications



Contact ORBi