Exploring the Impact of Cenomanian Paleogeography and Marine Gateways on Oceanic Oxygen

Abstract

The Cenomanian-Turonian is a key period to study the oxygen and carbon cycles as it recorded one of their greatest disturbance, known as the Oceanic Anoxic Event 2 (OAE2) and characterized by the widespread deposition of organic-rich sediments (

Ventilation Changes Drive Orbital‐Scale Deoxygenation Trends in the Late Cretaceous Ocean

“…Threshold for dysoxia is setup at 62.5 mmol/m 3 following Middelburg and Levin (2009) (thick black line) to keep consistency with Laugié et al. (2021), although the value of mmol/m 3 is also find in literature (Tyson & Pearson, 1991) (dashed black line). (b) Percentage of ocean volume below anoxia and dysoxia thresholds in the Atlantic region, Left: Atlantic Basin; Middle: Northern Atlantic Basin; Right: Southern Atlantic basin (south of the Walvis Ridge).…”

“…In our simulations, most of the ocean and ocean seafloor remain oxic with exception of the Atlantic basin (Figure 1a and Figures S4 and S5 in Supporting Information ), such as already described by Laugié et al. (2021). Strong oxygenation is simulated from the seafloor to the subsurface in the southern Pacific ocean (>250 mmol/m 3 ) as well as in the Arctic basin, while intermediate O 2 concentrations (80–120 mmol/m 3 ) are depicted in the Eastern Equatorial Pacific, on bathymetric highs in the Pacific ocean and Kerguelen Plateau as well as in the deepest part of the European Tethys (Figure 1a).…”

“…Ventilation of the global ocean in our simulations is forced by deep water formation in the southern Pacific Ocean (Figure 3a), as simulated for late Cretaceous configurations in previous studies (e.g., Ladant et al., 2020; Laugié et al., 2021; Monteiro et al., 2012). Highly oxygenated waters spread in the deep Pacific basin and then recirculate through the Tethys and northern Pacific Oceans before eventually reaching the Atlantic Ocean through the Central American Seaway, gradually losing oxygen along their journey (Laugié et al., 2021). Already strongly O 2 ‐depleted Pacific Ocean deep waters (>2,500 m) therefore feed the Central Atlantic basin (Laugié et al., 2021), which is the most sensitive basin to oxygen depletion in our orbital set of simulations (Figure 1b).…”

“…Highly oxygenated waters spread in the deep Pacific basin and then recirculate through the Tethys and northern Pacific Oceans before eventually reaching the Atlantic Ocean through the Central American Seaway, gradually losing oxygen along their journey (Laugié et al., 2021). Already strongly O 2 ‐depleted Pacific Ocean deep waters (>2,500 m) therefore feed the Central Atlantic basin (Laugié et al., 2021), which is the most sensitive basin to oxygen depletion in our orbital set of simulations (Figure 1b). The northward limit of highly oxygenated waters (>200 mmol/m 3 isoline on Figure S7 in Supporting Information ) in the southern deep Pacific Ocean is reduced in HOSP (40°S) compared to HO (15°S) because the overturning circulation is overall slower (up to 4 Sv decrease) when eccentricity is high (HOSP) (Figure 3b).…”

Neogene South Asian monsoon rainfall and wind histories diverged due to topographic effects

“…For this study, we have updated the scheme employed to compute the river supply of nutrients and other elements because the paleogeography is significantly different from present-day 55 . In the original version, elements' delivery is fixed and uses results from the Global Erosion Model 56 for DIC and alkalinity or is taken from the GLOBAL-NEWS2 data sets 57 for other elements.…”