Mineralogy and petrography of HAL, an isotopically-unusual Allende inclusion

Oxygen- and magnesium-isotope compositions of calcium–aluminum-rich inclusions from Rumuruti (R) chondrites

“…Surprisingly, the CAI was found in a type 4 lithology of the Hughes 030 chondrite, whereas other CAIs having no 26 Mg * (2446D/2L and 1476/124) were found in type 3 lithologies ( Table 1). The highly fractionated oxygen-isotope composition of this inclusion and the high 27 Al/ 24 Mg ratio of its hibonite (up to $57,000; Table 4) are similar to those in F-and HAL-like CAIs (e.g., Lee et al, 1979Lee et al, , 1980aAllen et al, 1980;Davis et al, 1982;Hinton and Bischoff, 1984;Ireland and Compston, 1987;Ireland et al, 1988Ireland et al, , 1992Russell et al, 1998;Ushikubo et al, 2007). The HAL-like inclusions are characterized by large mass-dependent fractionation of oxygen, calcium, and titanium isotopes, depletion in cerium, ytterbium, and europium, normal magnesium-isotope compositions, and resolvable 26 Mg * corresponding to a much lower ( 26 Al/ 27 Al) 0 compared to the canonical value (e.g., Lee et al, 1976;MacPherson et al, 1995).…”

“…On the basis of evaporation experiments on Type B CAI-like material, Richter et al (2002) suggested that significant fractionation of magnesium and silicon isotopes can be achieved by slow cooling at low ambient pressure and in the temperature range of 1400-1800°C. The large negative cerium anomalies seen in FUN and HAL-like inclusions (e.g., Lee et al, 1979Lee et al, , 1980aAllen et al, 1980;Davis et al, 1982;Hinton and Bischoff, 1984;Ireland and Compston, 1987;Ireland et al, 1988Ireland et al, , 1992Russell et al, 1998;Ushikubo et al, 2007) also suggest that their melting and vaporization took place under highly oxidizing conditions. Based on the experimental and isotopic data discussed above, the following model for the origin of H030/L can be proposed:…”

Mineralogical anatomy and implications of a Ti–Sc-rich ultrarefractory inclusion from Sayh al Uhaymir 290 CH3 chondrite

“…The lack of oxygen isotopic anomaly in the anosovite in A0031 based on our SCAPS data also supports this conclusion. The pseudobrookite-structure mineral anosovite (Ti 4+ ,Ti 3+ ,Mg,Sc,Al) 3 O 5 in A0031 joins various Ti-, Zr-, Y-, and Sc-rich oxides and silicates that have been observed in refractory inclusions from carbonaceous chondrites, including allendeite, tazheranite, zirconolite, panguite, thortveitite, lakargiite, eringaite, grossmanite, davisite, and kangite (Allen et al, 1980;Hinton et al, 1988;El Goresy et al, 2002;Rossman, 2008b, 2009b;Ma, 2011Ma, , 2012Ma et al, 2011Ma et al, , 2012Ma et al, , 2013Ma et al, , 2014. However, different from other Ti-, Zr-, Y-, and Sc-rich oxide and silicates, the presence of anosovite (Ti 4+ ,Ti 3+ ,Mg,Sc,Al) 3 O 5 in A0031 for the first time confirms the stability of Ti 3 O 5 in the early solar system, which was predicted in previous equilibrium condensation models (Yoneda and Grossman, 1995;Ebel and Grossman, 2000;Petaev and Wood, 2000).…”

A stellar origin for the short-lived nuclides in the early Solar System

“…But observations of enhanced ion fluxes in a molecular cloud 7 have led to other models [8][9][10] in which these nuclides are formed by energetic particle irradiation of gas and dust in the protosolar molecular cloud; alternatively, irradiation by energetic particles from the active early Sun may have occurred within the solar nebula itself [11][12][13][14][15][16][17][18] . Here we show that there is a correlation between the initial abundances of 41 Ca and 26 Al in samples of primitive meteorite (as inferred from their respective decay products, 41 K and 26 Mg), implying a common origin for the short-lived nuclides. We can therefore rule out the mechanisms based on energetic particle irradiation, as they cannot produce simultaneously the inferred initial abundances of both nuclides.…”

“…The relative abundances of these isotopes provide a means to determine timescales for the formation and accretion of primitive Solar System objects, the abundances of the parent nuclides being fixed when these objects solidified. The abundances can also be used to investigate the source of the nuclides (such as 41 Ca, 26 Al, 60 Fe, 53 Mn and 107 Pd), although this is an area of controversy. The nuclides could have originated from a single stellar object 2-6 , such as a nearby red-giant or a supernova.…”