Salts in two chondritic porous interplanetary dust particles

Rietmeijer, Frans J. M.

doi:10.1111/j.1945-5100.1990.tb00998.x

Cited by 14 publications

(6 citation statements)

References 17 publications

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“…In at least one of the enstatite chondrite CAIs (A295c), the Ti-phase is characterized by Ti,+ as well as Ti4+ and, thus, cannot be rutile or another Ti02 polymorph (Table 5). Titanium oxides with some Ti3+ have been reported from interplanetary dust particles (Rietmeijer and Mackinnon, 1990) and from matrices of carbonaceous chondrites (Brearley, 1993) and may be similar to the Ti-oxides we have identified in enstatite chondrite CAIs. Furthermore, the assemblage of CAIs in enstatite chondrites is distinct from assemblages of CAIs in other groups.…”

Section: Unique Assemblage Of Calcium-aluminum-rich Inclusions In Enssupporting

confidence: 73%

Calcium‐aluminum‐rich inclusions in enstatite chondrites (I): Mineralogy and textures

Fagan

Krot

Keil

2000

Meteorit & Planetary Scien

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Abstract-Like calcium-aluminum-rich inclusions (CAIs) from carbonaceous and ordinary chondrites, enstatite chondrite CAIs are composed of refractory minerals such as spinel, perovskite, A1,Ti-diopside, melilite, hibonite, and anorthitic plagioclase, which may be partially to completely surrounded by halos of Na-( +Cl)-rich minerals. Porous, aggregate, and compact textures of the refractory cores in enstatite chondrite CAIs and rare Wark-Lovering rims are also similar to CAIs from other chondrite groups. However, the small size ( 4 0 0 pm), low abundance ( 4 % by mode in thin section), occurrence of only spinel or hibonite-rich types, and presence of primary Ti-( +V)-oxides, and secondary geikelite and Ti,Fe-sulfides distinguish the assemblage of enstatite chondrite CAIs from other groups.The primary mineral assemblage in enstatite chondrite CAIs is devoid of indicators (e.g., oldhamite, osbornite) of low 0 fugacities. Thus, high-temperature processing of the CAIs did not occur under the reducing conditions characteristic of enstatite chondrites, implying that either (1) the CAIs are foreign to enstatite-chondrite-forming regions or (2) 0 fbgacities fluctuated within the enstatite-chondrite-forming region. In contrast, secondary geikelite and Ti-Fe-sulfide, which replace perovskite, indicate that alteration of perovskite occurred under reducing conditions distinct from CAIs in the other chondrite groups. We have not ascertained whether the reduced alteration of enstatite chondrite CAIs occurred in a nebular or parentbody setting. We conclude that each chondrite group is correlated with a unique assemblage of CAIs, indicating spatial or temporal variations in physical conditions during production or dispersal of CAIs.

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Section: Unique Assemblage Of Calcium-aluminum-rich Inclusions In Enssupporting

confidence: 73%

Calcium‐aluminum‐rich inclusions in enstatite chondrites (I): Mineralogy and textures

Fagan

Krot

Keil

2000

Meteorit & Planetary Scien

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“…Carbonates have been commonly identified in carbonaceous chondrites, micrometeorites, and IDPs (Sandford and Walker ; Tomeoka and Buseck ; Germani et al. ; Rietmeijer ; Bradley et al. ; Zolensky and Lindstrom ; Brearley ; Duprat et al.…”

Section: Discussionmentioning

confidence: 99%

Mineralogy and oxygen isotope systematics of magnetite grains and a magnetite‐dolomite assemblage in hydrated fine‐grained Antarctic micrometeorites

Dobricǎ

Ogliore

Engrand

et al. 2019

Meteorit & Planetary Scien

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We report the mineralogy and texture of magnetite grains, a magnetite‐dolomite assemblage, and the adjacent mineral phases in five hydrated fine‐grained Antarctic micrometeorites (H‐FgMMs). Additionally, we measured the oxygen isotopic composition of magnetite grains and a magnetite‐dolomite assemblage in these samples. Our mineralogical study shows that the secondary phases identified in H‐FgMMs have similar textures and chemical compositions to those described previously in other primitive solar system materials, such as carbonaceous chondrites. However, the oxygen isotopic compositions of magnetite in H‐FgMMs span a range of ∆17O values from +1.3‰ to +4.2‰, which is intermediate between magnetites measured in carbonaceous and ordinary chondrites (CCs and OCs). The δ18O values of magnetites in one H‐FgMM have a ~27‰ mass‐dependent spread in a single 100 × 200 μm particle, indicating that there was a localized control of the fluid composition, probably due to a low water‐to‐rock mass ratio. The ∆17O values of magnetite indicate that H‐FgMMs sampled a different aqueous fluid than ordinary and carbonaceous chondrites, implying that the source of H‐FgMMs is probably distinct from the asteroidal source of CCs and OCs. Additionally, we analyzed the oxygen isotopic composition of a magnetite‐dolomite assemblage in one of the H‐FgMMs (sample 03‐36‐46) to investigate the temperature at which these minerals coprecipitated. We have used the oxygen isotope fractionation between the coexisting magnetite and dolomite to infer a precipitation temperature between 160 and 280 °C for this sample. This alteration temperature is ~100–200 °C warmer than that determined from a calcite‐magnetite assemblage from the CR2 chondrite Al Rais, but similar to the estimated temperature of aqueous alteration for unequilibrated OCs, CIs, and CMs. This suggests that the sample 03‐36‐46 could come from a parent body that was large enough to attain temperatures as high as the OCs, CIs, and CMs, which implies an asteroidal origin for this particular H‐FgMM.

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“…Multiple lines of evidence suggest that CP-IDPs derive from short-period comets. First, their fine grained and fragile structure is consistent with properties of comets as inferred from the low strength of cometary meteors and the abundance of sub-m grains observed in cometary comae [66,67]. Second, CP-IDPs have C abundances that are more similar to comets than meteorites [51].…”

Section: Constraints On Idp Source Bodiesmentioning

confidence: 48%