A continental amplifier for marine carbon sequestration in a greenhouse ocean

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Author(s): Kennedy, Martin; Wagner, Thomas
Author Affiliation(s): Primary:
University of Adelaide, School of Earth and Environmental Science, Adelaide, South Aust., Australia
Newcastle University, United Kingdom
Volume Title: Goldschmidt 2011 abstract volume
Source: Mineralogical Magazine, 75(3), p.1170; Goldschmidt2011, Prague, Czech Republic, Aug. 14-19, 2011. Publisher: Mineralogical Society, London, United Kingdom. ISSN: 0026-461X CODEN: MNLMBB
Note: In English
Summary: Recent evidence has increased concern that future climate will be influenced by natural processes and feedbacks more common to a warm climate mode. It is well known from past greenhouse periods that anomalous concentrations of organic carbon were associated with disruption of marine ecosystems, widespread anoxia, and climate perturbations. While most models of black shale formation focus on oceanographic controls, findings on modern continental margin sediments also identify a strong landward influence on marine carbon burial that is also consistent with current understanding of hypoxic zone expansion. Here we show evidence for a direct land-sea mechanism that translates the effects of changing continental climate to carbon burial in deep marine sediments via the preservative effects of detrital clay mineral surfaces. We show a correlation (r2=0.75) at cm resolution between mineral surface area (MSA) and abrupt (centennial or less) high magnitude shifts in TOC from 1% to 15% in pelagic sediments from the tropical Cretaceous Atlantic (ODP 959). Carbon burial was maximized by an enhanced flux of high MSA clay minerals formed in response to increased seasonality in tropical Africa that were exported to hypoxic shelf waters with high dissolved organic carbon concentration. Not only do these data identify a dominating terrestrial influence for back shale formation during one of the 'Cretaceous Oceanic Anoxic Events' ∼ 85 ma (OAE3), but show that climate under greenhouse conditions can cross a threshold into a highly sensitive mode in which organic carbon burial efficiency is amplified, providing a negative feedback to pCO2,
Year of Publication: 2011
Research Program: ODP Ocean Drilling Program
Key Words: 22 Environmental Geology; Atlantic Ocean; Black shale; Carbon; Carbon dioxide; Carbon sequestration; Clastic rocks; Climate change; Climate effects; Continental crust; Continental lithosphere; Crust; Equatorial Atlantic; Greenhouse effect; Greenhouse gases; Leg 159; Lithosphere; North Atlantic; ODP Site 959; Ocean Drilling Program; Organic carbon; Paleoclimatology; Sedimentary rocks
Coordinates: N033740 N033740 W0024408 W0024408
Record ID: 2013082736
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Abstract, Copyright, Mineralogical Society of Great Britain and Ireland