The chondritic impactor origin of the Ni-rich component in Australasian tektites and microtektitesOPEN ACCESS 

· by · in ,

L. Folco, P. Rochette, M. D’Orazio, M. Masotta

Geochimica et Cosmochimica Acta
In Press, Journal Pre-proof, Available online 23 September 2023

LINK (OPEN ACCESS)

“In the Earth’s crust, Ni is generally concentrated in mafic and ultramafic rocks and is coupled with Mg in Mg-olivine, Mg-pyroxene and spinel. Whether the Ni-rich, and in general, the mafic component of Australasian tektites and microtektites is terrestrial or meteoritic is still debated. To test the origin of the Ni-rich component, we studied the Ni versus Mg distribution in a large geochemical database of Australasian tektites (n = 208) and microtektites (n = 238) from the literature. Nickel contents of up to 428 µg/g in tektites and 678 µg/g in microtektites covary with Mg in tektites and in most (∼85%) of the microtektites defining a mixing trend between crustal and chondritic values, thereby documenting the chondritic origin of the Ni-rich component in Australasian tektites/microtektites. Mixing calculations indicate up to 4% and up to 6% by weight chondritic component in tektites and microtektites, respectively. A possible mafic component of terrestrial origin is observed in a minority of tektite and microtektite specimens. This finding is consistent with previous works suggesting a possible occurrence of a chondritic signature in high-Ni tektites, based on the study of highly siderophile elements and Os isotopes, and high-Ni microtektites, based on Ni, Co, and Cr ratios. The combined geochemical and isotopic analysis of high-Ni tektites and microtektites in collections worldwide may thus reveal the chondritic impactor type that generated one of the presumably largest impacts in the Cenozoic.”

Related posts (automatically generated):

  1. On the Nature of the Ni-rich Component in Splash-form Australasian Tektites
  2. Australasian microtektites: Impactor identification using Cr, Co and Ni ratios
  3. Formation of Australasian tektites from gravity and magnetic indicatorsOPEN ACCESS 
  4. New clues from Earth’s most elusive impact crater: Evidence of reidite in Australasian tektites from Thailand
  5. New fission-track ages of australasian tektites define two age groups: Discriminating between formation and reset ages
  6. Australasian impact crater buried under the Bolaven volcanic field, Southern LaosOPEN ACCESS 
  7. Evidence for a chondritic impactor, evaporation-condensation effects and melting of the Precambrian basement beneath the ‘target’ Deccan basalts at Lonar crater, India
  8. Ultraprecise age and formation temperature of the Australasian tektites constrained by 40Ar/39Ar analyses
  9. Coeval ages of Australasian, Central American and Western Canadian tektites reveal multiple impacts 790 ka ago
  10. Sr-Nd-Pb isotope systematics of Australasian tektites: Implications for the nature and composition of target materials and possible volatile loss of Pb
Tags: , , , ,