@article{fdi:010092184,
  title = {{O}rigin of the {C}a-phosphate inclusions in {I}vory {C}oast and {A}ustralasian {M}uong-{N}ong-type tektites},
  author = {{Z}anetta, {P}. {M}. and {S}eydoux-{G}uillaume, {A}. {M}. and {R}ochette, {P}. and {R}eynard, {B}. and {T}ricaud, {V}. and {S}oro, {P}. and {S}ingsoupho, {S}. and {K}ouamelan, {A}. {N}. and {M}onda, {O}. and {B}aratoux, {D}avid},
  editor = {},
  language = {{ENG}},
  abstract = {{T}ektites are reduced ({F}e2+) glasses formed by the quenching of molten material ejected from {E}arth's surface as a result of a hypervelocity impact. {T}he vast majority of tektites are usually homogeneous glasses, but rare samples containing mineral inclusions can provide insights about the source material, sample thermal history, and tektite formation process. {T}ektites from two distinct strewn fields presenting {C}a-phosphate inclusions detected from anomalous magnetic susceptibility were studied: one sample from the {I}vory {C}oast tektite ({ICT}) field ejected at 1.07 {M}a from the {B}osumtwi crater (10.5 km in size) in {G}hana and two {M}uong {N}ong type samples from the {A}ustralasian tektite field ({MN}-{AAT}) ejected at 0.79 {M}a from a crater possibly situated in southeast {A}sia. {I}n {ICT}, {C}a-phosphate inclusions are systematically embedded in lechatelierite ({S}i{O}2 glass). {I}n {MN}-{AAT} {C}a-phosphate are either embedded in lechatelierite or in {F}e-rich glass forming schlieren. {M}ultiscale petrographic characterization using correlative microscopy associating scanning electron microscopy, microprobe and, transmission electron microscopy reveals that rounded inclusions in ivoirite are composed of acicular {C}a-phosphates (merrillite) embedded in an amorphous {P}-rich glass. {I}n {MN}-{AAT}, inclusions consist mostly of single droplets of {F}e-{M}g rich {C}a-phosphate (structurally related to apatite), but few droplets often forming an emulsion texture show a complex assemblage of apatite, magnetite, pyroxene, and spinel growing from a {P}t-rich nucleus. {D}iffusion profile around lechatelierite domains reveals maximum temperatures greater than 2200-2400 degrees {C} in the impact plume of the {A}ustralasian tektite and the {I}vory coast tektite. {H}eating time is of the order of seconds-tens of seconds rather than minutes as previously suggested (20 s for {MN}-{AAT} and 5 s for {ICT}). {T}he number, the density, and the fact that inclusions are entirely crystallized in {MN}-{AAT} support relatively slow cooling rates (<200 degrees {C}/h), in comparison with the faster cooling rates (>2000 degrees {C}/h) indicated by the precipitation of amorphous {P}-rich glass in {ICT}. {I}n both impact events, ejecta that had been heated to high temperatures did not remain in the vapor plume for an extended period of time and landed rapidly (within tens of seconds) at a relatively high temperature (>1000 degrees {C}) on the {E}arth's surface. {P}hosphate inclusions systematically embedded in lechatelierite in {ICT} provide clues about the source material. {I}t suggests that the parent material for these silica-rich inclusions is not conventional detrital quartz. {R}ather, parts of lechatelierite domains may be inherited from a biogenic source that could be consistent with tropical soil (source of the phosphor) and its biomass (silica of plant origin). {T}he reduction process that tektites record during their formation may be explained by superficial material since forests can contain a sizable mass of carbon that can reduce iron in tektites and produce platinoid-rich metallic nuclei and the {F}e3+/{S}igma {F}e gradient recorded by the dendritic spinels.},
  keywords = {{T}ektites ; {M}eteoritic impacts ; {M}ineral inclusions ; {G}lass ; {D}iffusion profiles ; {C}ooling rates ; {COTE} {D}'{IVOIRE} ; {ASIE} {DU} {SUD} {EST}},
  booktitle = {},
  journal = {{G}eochimica et {C}osmochimica {A}cta},
  volume = {387},
  numero = {},
  pages = {63--82},
  ISSN = {0016-7037},
  year = {2024},
  DOI = {10.1016/j.gca.2024.09.021},
  URL = {https://www.documentation.ird.fr/hor/fdi:010092184},
}