Development of box models for prediction of oxygen levels in paleoatmospheres

Conference · Tue Jan 01 04:00:00 EST 1985 · Geol. Soc. Am., Abstr. Programs; (United States)

OSTI ID:6199649

Kump, L R; Garrels, R M

A numerical model of the global sedimentary redox cycle is developed which is capable of predicting oxygen levels in paleoatmospheres. It includes the atmosphere as a distinct reservoir, and removes the direct coupling of the carbon and sulfur cycles of earlier models. Oxygen levels are determined by the fluxes of oxygen into the atmosphere, due to the burial or pyrite (FeS/sub 2/) and organic carbon (CH/sub 2/O), and by the fluxes out, due to the oxidative weathering of the sedimentary reservoirs of FeS/sub 2/ and CH/sub 2/O. After establishing a steady-state configuration for the coupled carbon and sulfur cycles, a perturbation is applied; specifically, the burial rate of CH/sub 2/O is increased by a third. The response of the carbon isotopic composition of the ocean to the perturbation is nearly instantaneous, while that of the sulfur isotopic composition is more sluggish, due to the buffering of the large oceanic sulfate reservoir. The oxygen level increases logarithmically, and stabilizes at a new, higher level within 40 m.y. The transfer of material between the oxidized and reduced reservoirs of C and S continues over 100's of m.y. as a new steady-state configuration for the coupled system is approached. Oxygen levels have been calculated from the isotopic records of C and S for the last 100 m.y. The model results are especially sensitive to our choice of the mean, initial isotopic values for the carbon reservoirs. However, our prediction of decreasing O/sub 2/ levels since the middle Miocene is corroborated by the recent model results of N.J. Shackleton.

• Research Organization: Univ. Southern Florida, St. Petersburg (USA)
• OSTI ID: 6199649
• Report Number(s): CONF-8510489-
• Conference Information: Journal Name: Geol. Soc. Am., Abstr. Programs; (United States) Journal Volume: 17
• Country of Publication: United States
• Language: English

Related Subjects

500200 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
580100* -- Geology & Hydrology-- (-1989)
ATMOSPHERIC CHEMISTRY
CARBON CYCLE
CARBON ISOTOPES
CHEMICAL REACTIONS
CHEMISTRY
EARTH ATMOSPHERE
ECOLOGICAL CONCENTRATION
ELEMENTS
ISOTOPE RATIO
ISOTOPES
MATHEMATICAL MODELS
NONMETALS
OXYGEN
PALEOCLIMATOLOGY
PALEONTOLOGY
REDOX REACTIONS
SULFUR CYCLE
SULFUR ISOTOPES