(2022). High rates of organic carbon burial in submarine deltas maintained on geological timescales. Nature Geoscience. 15 (11). 919-924. https://doi.org/10.1038/s41561-022-01048-4, https://archimer.ifremer.fr/doc/00799/91125/
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High rates of organic carbon burial in submarine deltas maintained on geological timescales
Burial 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.
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Publisher's official version | 17 | 3 Mo | ||
Source Data Fig. 2 Sample codes, Clinothem subdivision (x axis in Fig. 2b) and TOC content (y axis in Fig. 2b). | - | 15 Ko | ||
Source Data Fig. 3 Sample codes, stratigraphic position (y axis in Fig. 3a,b,c,d), described facies (x axis in Fig. 3a), TOC content (x axis in Fig. 3b), carbon stable isotopes (x axis in Fig. 3c),.. | - | 18 Ko | ||
Source Data Extended Data Fig. 2 Codes, geographic coordinates (UTM) and stratigraphic positions of each sample displayed in ED Fig. 2a and b. | - | 17 Ko | ||
Source Data Extended Data Fig. 4 Sample codes, stratigraphic position (y axis in ED Fig. 4a,b,c,d), described facies (x axis in Fig. 4a), carbon carbonate (TIC) content (x axis in ED Fig. 4b), ... | - | 18 Ko | ||
Source Data Extended Data Fig. 5 Sample codes, hydrogen index (y axis in ED Fig. 5a), oxygen index (x axis in ED Fig. 5a) and Tmax (x axis in ED Fig. 5b). | - | 26 Ko | ||
Source Data Extended Data Fig. 6 Sample codes, stratigraphic position, concentration of n-alkanes used to calculate the TAR ratio displayed in ED Fig. 6b and vitrinite reflectance data displayed in.. | - | 14 Ko | ||
Author's final draft | 28 | 1 Mo |
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