Everett K. Gibson

Thermal metamorphism of primitive meteorites. VIII - Noble gases, carbon and sulfur in Allende /C3/ meteorite heated at 400-1000 C

Abstract Noble gases, C and S are lost from Allende samples heated for 1 week at temperatures of 400–1000°C in a low pressure environment. In the extreme, losses of 3 He and 4 He are ~ 100 × while for C. S and Ne, Ar and Kr isotopes and 132 Xe. these are ≤10 ×. Except for He, these losses are less severe than those of Bi or Tl from samples heated in the same runs. Significant He. Ne and Ar isotopic fractionation during heating indicates preferential outgassing of specific reservoirs. Apparent activation energies for all species generally indicate loss controlled by a diffusive process. Next to He, 40 Ar is the most labile of those species considered here but still less so than Bi or Tl. L-group (but not H- or LL-group) chondrites may have lost mobile elements like Tl while being outgassed after late impact-associated heating. A less likely alternative possibility involving a collateral relation between condensation conditions and depth in a parent object may also explain the L-group trend.

Nature of the carbon and sulfur phases and inorganic gases in the Kenna ureilite

Abstract Abundances of carbon and sulfur in the Kenna ureilite are 2.219 ± 0.060 wt . % C and 0.179 ± 0.008 wt . % S. Secondary carbonates resulting from terrestrial weathering account for 0.25 ± 0.02 wt . % C. No hydrocarbons were detected during gas release measurements. Most of the carbon is in graphite, diamond, or lonsdaleite. The sample of Kenna contained 0.95 ± 0.05 wt . % H2O. Total carbon and sulfur measurements were made on three additional ureilites: Havero, Dingo Pup Donga, and North Haig. Ureilite carbon abundances are similar to those of C-2 chondrites, whereas sulfur abundances are a factor of 10 less than C-2 chondrites and ordinary chondrites. The elemental abundances, ratios, and phases present in the ureilites rule out a direct genetic relationship between the ureilites and the carbonaceous chondrites.

Volatiles in interplanetary dust particles: A comparison with volatile‐rich meteorites

Fourteen interplanetary dust particles (IDPs) have been analyzed for their volatiles using a laser microprobe/mass spectrometer technique. For comparison, a suite of 10 to 20 micron sized samples from the Orgueil (CI) and Murchison (CM) carbonaceous chondrites was analyzed. Comparison of the abundance patterns for the IDPs and meteorites suggests that the volatiles found within the IDPs are similar to those observed for the CM chondrites groundmass.