Response to the Comment by S.B. Simon, L. Grossman, and S.R. Sutton on “Valence state of titanium in the Wark-Lovering rim of a Leoville CAI as a record of progressive oxidation in the early Solar Nebula”

Young, Edward; Dyl, K. A.; Simon, Justin I.

doi:10.1016/j.gca.2012.01.029

Cited by 4 publications

(2 citation statements)

References 6 publications

(58 reference statements)

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“…Previous investigators also noticed that a Ti-rich/bearing mineral might have various Ti 3+ /Ti tot values within a single CAI or different Ti-rich/bearing minerals within a single CAI may also have various Ti 3+ /Ti tot values (e.g., Simon and Grossman, 2006;Simon et al, 1991Simon et al, , 2007Dyl et al, 2011;Ma et al, 2012). However, whether all the variations in Ti 3+ /Ti tot values within a single Ti-rich/bearing mineral and between different minerals within a single CAI reflect a change of oxygen fugacity in the early solar nebula is still an open question (e.g., Dyl et al, 2011;Ma et al, 2012Ma et al, , 2013Simon et al, 2012;Young et al, 2012). It deserves more investigations on natural CAIs in primitive chondrites and their analogs in synthetic experiments (e.g., Grossman et al, 2008;Paque et al, 2013;Doyle et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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

Zhang

Sakamoto

et al. 2015

Geochimica et Cosmochimica Acta

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Titanium-rich minerals are common in Ca-Al-rich inclusions from primitive chondrites. They are important not only for testing the condensation models for a gas with a solar composition, but also for constraining the redox conditions of the early solar nebula. In this study, we report the detailed mineralogical features and its oxygen isotope compositions of a Ti-Sc-rich ultrarefractory inclusion A0031 from a CH3 chondrite Sayh al Uhaymir 290. The A0031 inclusion has a compact and layered texture with the interior consisting of panguite, Sc-rich anosovite, Ti-rich davisite, and anorthite. A few hexaferrum, perovskite, and spinel crystals are present as inclusions in these minerals. Outside of Ti-rich davisite are a layer of Al-Ti-rich diopside and two grains of enstatite. This texture strongly suggests that A0031 has a condensation origin. Panguite is its third occurrence in nature and similar in composition to the type panguite from the Allende meteorite. Sc-rich anosovite in A0031 has a chemical formula of (Ti 4+ ,Ti 3+ ,Mg,Sc,Al) 3 O 5 with the pseudobrookite structure. This is the second report of Ti 3 O 5 in nature, but is the first description of anosovite formed in the solar nebula as an ultrarefractory phase. The discovery of Sc-rich anosovite in A0031 reveals the stability of Ti 3 O 5 in the early solar nebula and supports the prediction of previous equilibrium condensation calculations. The panguite, Sc-rich anosovite, and Ti-rich davisite in A0031 show a large variation in Ti 3+ /Ti tot . The primitive nature of A0031 implies that the variations in Ti 3+ /Ti tot among different Ti-rich minerals are primary features. We propose that the distribution of Ti 3+ and Ti 4+ could be controlled mainly by their various competition abilities of incorporating into these Ti-Sc-Al-rich minerals. Similarity of Ti 3+ /Ti tot value between Ti-rich davisite from A0031 and those in other carbonaceous chondrites indicates that most refractory inclusions might have formed in highly reducing nebular settings. The 16 O-depleted isotope compositions of A0031 confirm the existence of diverse oxygen reservoirs for CH CaAl-rich inclusions in the solar nebula.

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Section: Introductionmentioning

confidence: 99%

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

Zhang

Sakamoto

et al. 2015

Geochimica et Cosmochimica Acta

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“…Thus, the composition of the PSN and the canonical conditions for the inner Solar System, i.e., p H2 = 10 -3 atm, N 2 /H 2 ≈ 1  10 -4 (Anders and Grevesse, 1989), T = 1500 K, log fO 2 = -19 (Grossman et al, 2008), would have allowed for up to ~35 ppm of nebular N to be dissolved as N 3-species into a basaltic melt (i.e., the only composition for which the N solubility as a function of fO 2 has been determined; Libourel et al, 2003). While the conditions were initially reducing enough for the dissolution of several ppm nebular N, the oxygen fugacity increased from solar to protoplanetary (chondritic) over time Dyl et al, 2011;Young et al, 2012), possibly within the first 0.1 to 0.3 Ma , which reduced the nitrogen solubility in CAI melts to virtually zero. Consequently, during remelting events at a higher fO 2 , nitrogen was lost from CAIs, and the 15 N/ 14 N ratio of the liquid evolved according to:…”

Section: Trapped 15 N-rich Non-solar N In the Caimentioning

confidence: 99%