Enhanced continental weathering activity at the onset of the mid-Cenomanian Event (MCE)

Yobo, Lucien Nana; Brandon, A.D.; Lauckner, L.M.; Eldrett, J.S.; Bergman, S.C.; Minisini, D.

doi:10.7185/geochemlet.2231

Cited by 2 publications

References 22 publications

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Oceanic Anoxic Event 2 triggered by Kerguelen Plateau volcanism

Walker-Trivett,

Kender,

Bogus

et al. 2023

Preprint

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Large Igneous Province (LIP) volcanism is thought to have been the main cause of global warming, ocean anoxia and carbon cycle perturbations associated with Cretaceous Oceanic Anoxic Event 2 (OAE2, ~94 Ma). However, there is still no consensus on the timing and role volcanism played in triggering carbon cycle changes, or the source of the volcanism that has been previously ascribed to either the Caribbean LIP or High Arctic LIP. Here, we refine the stratigraphic position of OAE2 and the Mid-Cenomanian Event (MCE, ~96.5 Ma) at two sites in the Mentelle Basin (offshore southwestern Australia), and use sedimentary mercury (Hg) abundance to determine the timing of volcanism. Contrary to many Northern Hemisphere records, we report elevated levels of Hg and Hg/total organic carbon (TOC), suggesting OAE2 was initiated by a volcanic source proximal to the Mentelle Basin, such as the Kerguelen LIP. Distinct Hg/TOC pulses preceding the onset of OAE2, and in conjunction with its main phase, suggest volcanic emissions played a central role in triggering and controlling climatic and carbon cycle changes within OAE2. By contrast, we find little evidence to suggest a Southern Hemisphere volcanic episode initiated the MCE. Benthic foraminiferal assemblages and bulk sediment isotopes indicate volcanism caused elevated productivity and probable upwelling in the Southern Hemisphere Mentelle Basin for the duration of OAE2, similar to Northern Hemisphere records.

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Oceanic Anoxic Event 2 triggered by Kerguelen Plateau volcanism

Walker-Trivett,

Kender,

Bogus

et al. 2023

Preprint

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Warming drove the expansion of marine anoxia in the equatorial Atlantic during the Cenomanian leading up to Oceanic Anoxic Event 2

Abraham,

Naafs,

Lauretano

et al. 2023

Clim. Past

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Abstract. Oceanic Anoxic Event 2 (OAE 2) (∼ 93.5 Ma) is characterized by widespread marine anoxia and elevated burial rates of organic matter. However, the factors that led to this widespread marine deoxygenation and the possible link with climatic change remain debated. Here, we report long-term biomarker records of water-column anoxia, water-column and photic zone euxinia (PZE), and sea surface temperature (SST) from Demerara Rise in the equatorial Atlantic that span 3.8 Myr of the late Cenomanian to Turonian, including OAE 2. We find that total organic carbon (TOC) content is high but variable (0.41 wt %–17 wt %) across the Cenomanian and increases with time. This long-term TOC increase coincides with a TEX86-derived SST increase from ∼ 35 to 40 ∘C as well as the episodic occurrence of 28,30-dinorhopane (DNH) and lycopane, indicating warming and expansion of the oxygen minimum zone (OMZ) predating OAE 2. Water-column euxinia persisted through much of the late Cenomanian, as indicated by the presence of C35 hopanoid thiophene but only reached the photic zone during OAE 2, as indicated by the presence of isorenieratane. Using these biomarker records, we suggest that water-column anoxia and euxinia in the equatorial Atlantic preceded OAE 2 and this deoxygenation was driven by global warming.

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Enhanced continental weathering activity at the onset of the mid-Cenomanian Event (MCE)

Cited by 2 publications

References 22 publications

Oceanic Anoxic Event 2 triggered by Kerguelen Plateau volcanism

Oceanic Anoxic Event 2 triggered by Kerguelen Plateau volcanism

Warming drove the expansion of marine anoxia in the equatorial Atlantic during the Cenomanian leading up to Oceanic Anoxic Event 2

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