VARELA Maria Eugenia
congresos y reuniones científicas
Isotopically heavy and heterogeneous C in graphite of the Vaca Muerta mesosiderite
MARUOKA T,; MARIA EUGENIA VARELA; KURAT G,; ZINNER ERNST,
Congreso; Lunar and Planetary Sciences Conference; 2006
The genetic models for mesosiderites are still highly controversial. The most popular model considers mesosiderites as to be a mixture of crustal and core material from a differentiated asteroidal body. Several mechanisms for the silicate-metal mixing ? a non-trivial task - have been proposed [1-4] but all are incapable of fully explaining mesosiderite petrographic, geochemical and isotopic features. Consequently, complex scenarios were designed like the proposal that mesosiderites formed by fragmentation and re-accretion of a large (~ 200-400 km diameter) differentiated asteroid . Common to all genetic models proposed is the need to have Fe-Ni metal in a molten state during mixing with the silicate phases [3-5].Here we report on C-bearing FeNi metal objects and C isotopic ratios of graphite associated with the metal. Our results severely constrain the conditions prevailing during formation of the Vaca Muerta mesosiderite.