@article{PAR00000310,
  title = {{S}ignificance of iron isotope mineral fractionation in pallasites and iron meteorites for the core-mantle differentiation of terrestrial planets},
  author = {{P}oitrasson, {F}ranck and {L}evasseur, {S}. and {T}eutsch, {N}.},
  editor = {},
  language = {{ENG}},
  abstract = {{S}even bulk chondrites, with delta(57){F}e/{F}e-54 values between -0.1 parts per thousand and 0 parts per thousand relative to {IRMM}-14, tend to be slightly lighter than 11 bulk iron meteorites, which have delta(57){F}e/{F}e-54 values ranging from 0.04 parts per thousand to 0.2 parts per thousand. {A}t the mineral scale, taenite from two iron meteorites, {C}ranbourne and {T}oluca, shows delta(57){F}e/{F}e-54 values heavier by up to 0.3 parts per thousand than their kamacite counterpart, thus calling into question the significance of bulk iron meteorite data. {O}n three pallasites ({E}squel, {M}arjalahti and {S}pringwater) we measured a heavier iron isotope composition for the metal fractions compared to the coexisting olivines as previously observed on two other pallasites ({E}agle {S}tation and {I}milac), but the range of delta(57){F}e/{F}e-54 differences (from 0.32 parts per thousand to 0.07 parts per thousand) is larger than that originally found. {T}roilite from two pallasites appears to be even heavier than the metal fraction, whereas schreibersite is lighter than its olivine counterpart. {T}here is thus a general tendency for minerals within a given rock to show a heavier {F}e isotope composition as the coordination number of {F}e increases, although troilite is an exception to this rule. {I}ron meteorites are classically considered as remnants of asteroid cores and pallasites as core-mantle interfaces. {T}he simultaneous finding that the metal fractions of pallasites have a higher delta(57){F}e/{F}e-54 signature than the coexisting olivines, and that the iron meteorites are slightly heavier than chondrites could be taken as an indication that planetary core-mantle differentiation is accompanied by sizeable iron isotope fractionation. {I}n this hypothesis, mass balance constraints imply that resultant planetary mantles should be isotopically lighter than the chondritic starting material. {T}hat is not observed, however, since all planetary mantles analyzed so far have delta(57){F}e/{F}e-54 values equivalent to or heavier than those of chondrites. {I}t thus appears that the moderate temperature and pressure metal-silicate fractionation that occurred in pallasite and iron parent bodies is not readily transposable to planets as far as {F}e isotopes are concerned. {I}nstead, these mantle signatures could reflect equilibrium fractionation at a higher temperature, or the lack of a global core-mantle equilibration at the planetary scale. {O}verall, these new results show that the mass-dependent isotopic scatter observed among inner solar system bodies from the bulk-rock to the planetary scale (-0.3 parts per thousand delta(57){F}e/{F}e-54) is more restricted than previously thought. {T}his likely confirms a homogenization process that occurred in the protoplanetary accretion disk, between refractory inclusion condensation and chondrule formation. (c) 2005 {E}lsevier {B}.{V} {A}ll rights reserved.},
  keywords = {{F}e isotopes ; chondrites ; pallasites ; iron meteorites ; core mantle differentiation ; protoplanetary accretion disk},
  booktitle = {},
  journal = {{E}arth and {P}lanetary {S}cience {L}etters},
  volume = {234},
  numero = {1-2},
  pages = {151--164},
  ISSN = {0012-821{X}},
  year = {2005},
  DOI = {10.1016/j.epsl.2005.02.010},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00000310},
}