Experimental constraints on ureilite petrogenesis

Singletary, S. J.; Grove, T. L.

doi:10.1016/j.gca.2005.10.034

Cited by 24 publications

(16 citation statements)

References 25 publications

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“…It was developed as an idea well before the oxygen isotope trend in ureilites was recognized (Berkley and Jones ; Goodrich et al. ), and it has continued to be discussed since then (Walker and Grove ; Singletary and Grove , ; Goodrich et al. , , ).…”

Section: Comparisons Between Ureilites and Other Meteoritesmentioning

confidence: 99%

“…Plausible mechanisms for this implied radial gradient in ∆ 17 O have not been identified (Goodrich et al. ; Goodrich and Wilson ), although Singletary and Grove () have argued for a smelting model in which the 26 Al necessary for melting was concentrated in 16 O‐rich regions with high CAI concentrations. They infer that the CAI‐rich regions became hotter and rose inside the body due to gas produced during smelting.…”

Section: Comparisons Between Ureilites and Other Meteoritesmentioning

confidence: 99%

“…Carbon (average 3 wt% graphite with possible fine-grained diamond) generally resides along the boundaries of the silicate grains, together with a little metal and sulfide. The silicates commonly display a grain-shape alignment which was formerly regarded as an igneous cumulate texture (Berkley et al 1980) though it may have resulted from diapirism (Singletary and Grove 2006). The remaining 5% of ureilites are polymict breccias, and include some regolith breccias Downes et al 2008).…”

Section: Ureilites and Their Historymentioning

confidence: 99%

“…The internal pressure throughout its deeper interior was probably more than 80-100 bars (8)(9)(10). These estimates are based on thermodynamic calculations and experimental simulation of the coexisting carbon and Fe-bearing olivine observed in ureilites (Walker and Grove 1993;Singletary and Grove 2006; fig. 4 of Warren 2012).…”

Section: Ureilites and Their Historymentioning

confidence: 99%

“…The silicates commonly display a grain‐shape alignment which was formerly regarded as an igneous cumulate texture (Berkley et al. ) though it may have resulted from diapirism (Singletary and Grove ). The remaining 5% of ureilites are polymict breccias, and include some regolith breccias (Goodrich et al.…”

Section: Introductionmentioning

confidence: 99%

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Origin of mass‐independent oxygen isotope variation among ureilites: Clues from chondrites and primitive achondrites

Sanders

Scott

Delaney

2017

Meteorit & Planetary Scien

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Ureilite meteorites are abundant, carbon‐rich, primitive achondrites made of coarse‐grained, equilibrated olivine and pyroxene (usually pigeonite). They probably sample the baked, heterogeneous, melt‐depleted mantle of a large, once‐chondritic parent body that was broken up catastrophically while still young and hot. Heterogeneity in the parent body is inferred from a considerable “slope‐1” variation from one meteorite to another in oxygen isotopes (−2.5‰ < Δ17O < −0.2‰), which correlates with both molar FeO/MgO (range 0.03–0.35) and molar FeO/MnO (range 3–57), i.e., Δ17O correlates with the redox state. No consensus has yet emerged on the cause of these correlated trends. One view favors their inheritance via silicates from hot nebular (preaccretion) processes. Another invokes smelting (reduction of FeO by C in the hot parent body). Here, guided mainly by similar trends among equilibrated ordinary and R chondrites, studies of their unequilibrated counterparts, and work on other primitive achondrites, we propose a new model for ureilites in which the parent body accreted nebular ice with high‐∆17O, Mg‐rich silicates with low ∆17O, and varying amounts of metallic iron. Water from the thawing ice then oxidized the metal yielding secondary FeO‐bearing minerals with high ∆17O that, with metamorphism, became incorporated into the ureilite silicates. FeO/MgO, FeO/MnO, and ∆17O correlate because they rose in unison by amounts that varied spatially, depending on the local amount of metal that was oxidized. We suggest that the parent body was so large (radius ≫ 100 km) that smelting was inhibited and that carbon played a passive role in ureilite evolution. Although ureilites are regarded as complicated meteorites, we believe our analysis explains their mass‐independent oxygen isotope trend and related FeO variation through well‐understood processes and enlightens our understanding of the evolution of early planetesimals from cold, wet bodies to hot, dry ones.

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