ON TYPE B CAI FORMATION: EXPERIMENTAL CONSTRAINTS ON FO2 VARIATIONS IN SPINEL MINOR ELEMENT PARTITIONING AND REEQUILIBRATION EFFECTS
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dc.contributor.author | Connolly Jr.H.C. | |
dc.contributor.author | Burnett D.S. | |
dc.date.accessioned | 2021-11-19T02:29:10Z | |
dc.date.available | 2021-11-19T02:29:10Z | |
dc.date.issued | 2003 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=12090681 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2003, 67, 22, 4429-4434 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/32230 | |
dc.description.abstract | We report data from a series of dynamic crystallization experiments that focus on determining the partition coefficients (D’s) for V and Ti in the spinel + liquid system of an average type B1 CAI bulk composition for three different fO2 conditions. Partitioning data for Ca and Si are also obtained. We show that the D’s for V and Ti are fO2 dependent with DTi decreasing at low oxygen fugacity due to the presence of Ti3+. DV is essentially 0 in air, rises to 2.2 at the Fe-FeO buffer and drops to 1.4 at the C-CO buffer. This indicates that V3+ is highly compatible in spinel and that higher and lower valence states are much less compatible. We also report data from isothermal experiments that determine diffusion times for V and Ti in same system at a temperature close to the Tmax for type B1 CAIs. Diffusion of these elements between spinel and liquid is surprisingly rapid, with essentially total equilibration of Ti and V between spinel and liquid in 90 h run duration. Lack of equilibration of Cr, Si, and Ca shows that the Ti and V equilibration mechanism was diffusion and not dissolution and reprecipitation. Our experimental run durations set an upper limit of a few tens of hours on the time that type B1 CAIs were at their maximum temperature. Based on our data we argue that subsolidus reequilibration between spinel inclusion and host-silicate phases within type B CAIs likely explains the observed range of V and Ti concentrations in spinels which are inclusions in clinopyroxene. | |
dc.title | ON TYPE B CAI FORMATION: EXPERIMENTAL CONSTRAINTS ON FO2 VARIATIONS IN SPINEL MINOR ELEMENT PARTITIONING AND REEQUILIBRATION EFFECTS | |
dc.type | Статья |
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