The evolution of atmospheric CO sub 2 on Mars: The perspective from carbon isotope measurements

Conference · Thu Aug 30 04:00:00 EDT 1990 · Journal of Geophysical Research; (United States)

OSTI ID:5453021

Wright, I P; Grady, M M; Pillinger, C T ^[1]

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1. The Open Univ., Milton Keynes (England)

In situ measurements of {sup 12}C/{sup 13}C of atmospheric CO{sub 2} on Mars made by Viking are, within error, similar to values normally encountered on Earth. However, high precision isotopic measurements made on SNC meteorites show there to be a 40{per thousand} fractionation between carbon associated with silicate minerals ({delta}{sup 13}C {approx} {minus}25{per thousand}, {sup 12}C/{sup 13}C {approx} 91.3) and trapped CO{sub 2} gas or carbonate minerals ({delta}{sup 13}C {approx} +15{per thousand}, {sup 12}C/{sup 13}C {approx} 87.7). To a first approximation, it can be considered that the silicate-sited carbon in SNC meteorites carries the isotopic signature of the element present at depth in the Martian crust; herein it is considered that this magmatic carbon is representative of bulk Mars. On the other hand, carbon in the form of carbonate most probably results from secondary processes in operation at the surface of the planet. Trapped CO{sub 2} is thought to be a sample of Martian atmospheric gas. The significant difference in isotopic composition between the different components in SNC meteorites is difficult to interpret in terms of closed-system equilibrium or kinetic isotopic fractionation effects. Rather, it seems that the relative enrichment of {sup 13}C in surficial carbon is due to preferential removal of the lighter isotope during an atmospheric loss process. Between 30 and 70 mbar of CO{sub 2} may have been lost from the atmosphere to outer space.

• OSTI ID: 5453021
• Report Number(s): CONF-9001119--
• Conference Information: Journal Name: Journal of Geophysical Research; (United States) Journal Volume: 95:B9
• Country of Publication: United States
• Language: English

Related Subjects

640107* -- Astrophysics & Cosmology-- Planetary Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONATES
CHALCOGENIDES
CHEMICAL COMPOSITION
ISOTOPE RATIO
MARS PLANET
METEORITES
OXIDES
OXYGEN COMPOUNDS
PLANETARY ATMOSPHERES
PLANETARY EVOLUTION
PLANETS
REMOVAL
SOLAR SYSTEM EVOLUTION