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On the track of the elusive Sudbury impact: geochemical evidence for a chondrite or comet bolide
Author(s) -
Petrus Joseph A.,
Ames Doreen E.,
Kamber Balz S.
Publication year - 2015
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/ter.12125
Subject(s) - geology , chondrite , mafic , geochemistry , ordinary chondrite , impact crater , shock metamorphism , lithophile , crust , continental crust , enstatite , hypervelocity , meteorite , mineralogy , astrobiology , partial melting , astronomy , physics
Siderophile and lithophile trace element data for 69 samples from the Sudbury impact crater fill (Onaping Formation) and quartz diorite offset dikes help constrain the sources of the established moderately elevated platinum group element signature associated with the impact structure. The siderophile element distribution of the crater fill requires contributions from bulk continental crust, mafic rocks and a chondritic component. A mantle component is absent, but the involvement of mid to lower crust is implied. After considering post‐impact hydrothermal alteration, melt heterogeneity and mafic target admixture, the projectile elemental ratios were determined on a more robust data subset. Chondrite discrimination diagrams of these ratios identify an ordinary or enstatite chondrite as the most probable source of meteoritic material in the Sudbury crater fill. However, the relative and absolute siderophile element distributions within the impact structure as well as bolide size models are congruent with the bolide being a comet that had a chondritic refractory component.