Petrology and geochemistry of a silicate clast from the Mount Padbury mesosiderite: Implications for metal‐silicate mixing events of mesosiderite

Abstract— Petrological and bulk geochemical studies were performed on a large silicate clast from the Mount Padbury mesosiderite. The silicate clast is composed mainly of pyroxene and plagioclase with minor amounts of ilmenite, spinel, and other accessory minerals, and it shows subophitic texture. Pyroxenes in the clast are similar to those in type 5 eucrites and could have experienced prolonged thermal metamorphism after rapid crystallization from a near‐surface melt. Ilmenite and spinel vary chemically, indicating growth under disequilibrium conditions. The clast seems to have experienced an episode of rapid reheating and cooling, possibly as a result of metal‐silicate mixing. Abundances of siderophile elements are obviously higher than in eucrites, although the clast is also extremely depleted in highly siderophile elements. The fractionated pattern can be explained by injection of Fe‐FeS melts generated by partial melting of metallic portions during metal‐silicate mixing.

[1]  A. Jambon,et al.  Oxygen Isotope Variation in Stony-Iron Meteorites , 2006, Science.

[2]  H. Haack,et al.  Rapid Timescales for Accretion and Melting of Differentiated Planetesimals Inferred from 26Al-26Mg Chronometry , 2005 .

[3]  D. Mittlefehldt.  Ibitira: A basaltic achondrite from a distinct parent asteroid and implications for the Dawn mission , 2005 .

[4]  N. Shirai,et al.  Precise determination of PGE in a GSJ reference sample JP-1 by ID-ICPMS after nickel sulfide fire assay preconcentration , 2003 .

[5]  N. Shirai,et al.  Chemical composition of Yamato (Y) 000593 and Yamato 000749: Neutron-induced prompt gamma-ray analysis study , 2003 .

[6]  John H. Jones,et al.  An experimental test of Henry's Law in solid metal‐liquid metal systems with implications for iron meteorites , 2003 .

[7]  R. Clayton,et al.  A New Source of Basaltic Meteorites Inferred from Northwest Africa 011 , 2002, Science.

[8]  G. J. Taylor,et al.  Post-crystallization reheating and partial melting of eucrite EET90020 by impact into the hot crust of asteroid 4Vesta ∼4.50 Ga ago , 2001 .

[9]  H. Haack,et al.  Formation of mesosiderites by fragmentation and reaccretion of a large differentiated asteroid , 2001 .

[10]  H‐P. Hermann,et al.  Compositional properties of coexisting orthopyroxene and spinel in some Antarctic diogenites: Implications for thermal history , 2001 .

[11]  J. Blichert‐Toft,et al.  The differentiation of eucrites: The role of in situ crystallization , 2000 .

[12]  A. Rubin.  Formation of large metal nodules in ordinary chondrites , 1999 .

[13]  K. Lodders,et al.  Survey and evaluation of eucrite bulk compositions , 1998 .

[14]  Hiroshi Takeda,et al.  Metamorphic transformations of opaque minerals in some eucrites , 1998 .

[15]  E. Scott,et al.  Constraints on the role of impact heating and melting in asteroids , 1997 .

[16]  M. Ebihara,et al.  Precise determination of rare earth elements, thorium and uranium in chondritic meteorites by inductively coupled plasma mass spectrometry — a comparative study with radiochemical neutron activation analysis , 1997 .

[17]  G. J. Taylor,et al.  Global Crustal Metamorphism of the Eucrite Parent Body , 1996 .

[18]  H. Haack,et al.  Thermal and shock history of mesosiderites and their large parent asteroid , 1996 .

[19]  R. Clayton,et al.  Oxygen isotope studies of achondrites , 1996 .

[20]  G. Wasserburg,et al.  Sm-Nd chronology and petrogenesis of mesosiderites , 1994 .

[21]  A. Rubin.  A shock-metamorphic model for silicate darkening and compositionally variable plagioclase in CK and ordinary chondrites , 1992 .

[22]  D. Mittlefehldt,et al.  Classification of mafic clasts from mesosiderites - Implications for endogenous igneous processes , 1992 .

[23]  H. Takeda,et al.  Degree of equilibration of eucritic pyroxenes and thermal metamorphism of the earliest planetary crust , 1991 .

[24]  Mark S. Ghiorso,et al.  Chromian spinels as petrogenetic indicators : thermodynamics and petrological applications , 1991 .

[25]  M. Kimura,et al.  New enclaves in the Vaca Muerta mesosiderite: Petrogenesis and comparison with HED meteorites , 1991 .

[26]  A. Rubin,et al.  Compositions of large metal nodules in mesosiderites: Links to iron meteorite group IIIAB and the origin of mesosiderite subgroups , 1990 .

[27]  M. Ebihara,et al.  Enclaves in the Mt.Padbury and Vaca Muerta mesosiderites: Magmatic and residue (or cumulate) rock types , 1990 .

[28]  D. Mittlefehldt.  Petrogenesis of mesosiderites: I. origin of mafic lithologies and comparison with basaltic achondrites , 1990 .

[29]  A. Rubin,et al.  Compositional differences between basaltic and gabbroic clasts in mesosiderites , 1988 .

[30]  Eric A. Jerde,et al.  Diverse Eucritic Pebbles in the Vaca Muerta Mesosiderite: Una Manada de las Vacas Muertas , 1987 .

[31]  E. Jerde,et al.  Composition and origin of Nuevo Laredo Trend eucrites , 1987 .

[32]  A. Rubin,et al.  Formation of mesosiderites by low-velocity impacts as a natural consequence of planet formation , 1985, Nature.

[33]  H. Takeda,et al.  The polymict eucrites , 1984 .

[34]  R. Greenberg,et al.  Asteroids and meteorites: origin of stony-iron meteorites at mantle-core boundaries , 1984 .

[35]  R. Hewins.  Impact versus internal origins for mesosiderites , 1983 .

[36]  John H. Jones,et al.  Experimental investigations of trace element fractionation in iron meteorites, II: The influence of sulfur , 1983 .

[37]  R. Kretz.  Transfer and exchange equilibria in a portion of the pyroxene quadrilateral as deduced from natural and experimental data , 1982 .

[38]  S. Karato,et al.  Dynamic recrystallization of olivine single crystals during high‐temperature creep , 1980 .

[39]  D. Mittlefehldt.  Petrographic and chemical characterization of igneous lithic clasts from mesosiderites and howardites and comparison with eucrites and diogenites , 1979 .

[40]  D. Walker,et al.  Dynamic crystallization of a eucrite basalt. , 1978 .

[41]  E. Stolper.  Experimental petrology of eucritic meteorites , 1977 .

[42]  B. N. Powell.  Petrology and chemistry of mesosiderites—I. Textures and composition of nickel-iron , 1969 .

[43]  Mlm,et al.  Chromian spinels as petrogenetic indicators: Thermodynamics and petrological applications , 2007 .

[44]  A. Yamaguchi,et al.  Heating Experiments of the HaH 262 Eucrite and Implication for the Metamorphic History of Highly Metamorphosed Eucrites , 2005 .

[45]  Timothy J. McCoy,et al.  Non-chondritic meteorites from asteroidal bodies , 1998 .

[46]  Jane Jones.  Mesosiderites: (1) Reevaluation of Cooling Rates and (2) Experimental Results Bearing on the Origin of Metal , 1983 .

[47]  J. Delaney,et al.  Metamorphism in mesosiderites , 1982 .

[48]  G. Harlow,et al.  Clouding of pyroxene and plagioclase in eucrites - Implications for post-crystallization processing , 1980 .

[49]  R. J. Floran.  Silicate petrography, classification, and origin of the mesosiderites: Review and new observations. , 1978 .

[50]  P. Ramdohr,et al.  Subsolidus reduction of lunar opaque oxides - Textures, assemblages, geochemistry, and evidence for a late-stage endogenic gaseous mixture , 1975 .

[51]  R. W. Bild,et al.  Mesosiderites. I - Compositions of their metallic portions and possible relationship to other metal-rich meteorite groups , 1974 .

[52]  B. N. Powell.  Petrology and chemistry of mesosiderites—II. Silicate textures and compositions and metal-silicate relationships☆ , 1971 .

[53]  Yuji Tazawa,et al.  Chemical composition of , 1970 .

[54]  G. Mccall.  The Petrology of the Mount Padbury Mesosiderite and Its Achondrite Enclaves , 1966 .