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TitleHigh rates of organic carbon burial in submarine deltas maintained on geological timescales
AuthorHage, S; Romans, B WORCID logo; Peploe, T G E; Poyatos-More, MORCID logo; Haeri Ardakani, OORCID logo; Bell, D; Englert, R G; Kaempfe, S A; Nesbit, P R; Sherstan, G; Synnott, D PORCID logo; Hubbard, S MORCID logo
SourceNature Geoscience 2022 p. 1-17, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20220031
PublisherNature Portfolio
Mediapaper; digital; on-line
File formatpdf; html
Subjectsgeneral geology; Science and Technology; Nature and Environment; organic carbon
Illustrationssatellite imagery; diagrams; cross-plots; charts; photographs; tables
ProgramEnergy Geoscience Clean Energy Resources - Decreasing Environmental Risk
Released2022 10 24
AbstractBurial of terrestrial organic carbon in marine sediments can draw down atmospheric CO2 levels on Earth over geologic timescales (=105 yr). The largest sinks of organic carbon burial in present-day oceans lie in deltas, which are composed of three-dimensional sigmoidal sedimentary packages called clinothems, dipping from land to sea. Analysis of modern delta clinothems, however, provides only a snapshot of the temporal and spatial characteristics of these complex systems, making long-term organic carbon burial efficiency difficult to constrain. Here we determine the stratigraphy of an exhumed delta clinothem preserved in Upper Cretaceous (~75 million years ago) deposits in the Magallanes Basin, Chile, using field measurements and aerial photos, which was then combined with measurement of total organic carbon to create a comprehensive organic carbon budget. We show that the clinothem buried 93 ± 19 Mt terrestrial-rich organic carbon over a duration of 0.1-0.9 Myr. When normalized to the clinothem surface area, this represents an annual burial of 2.3-15.7 t km-2 yr-1 organic carbon, which is on the same order of magnitude as modern-day burial rates in clinothems such as the Amazon delta. This study demonstrates that deltas have been and will probably be substantial terrestrial organic carbon sinks over geologic timescales, a long-standing idea that had yet to be quantified.
Summary(Plain Language Summary, not published)
Burial of terrestrial organic carbon in marine sediments can draw down atmospheric CO2 levels on Earth over geologic timescales (=105 yr). This study compared a comprehensive organic carbon budget for an exhumed ancient delta preserved in Upper Cretaceous (~75 Ma) deposits in the Magallanes Basin, Chile with modern deltas such as the Amazon delta to show the significance of burial of terrestrial organic carbon in drawing down atmospheric CO2 levels.

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