Identification of the projectile at the Brent crater, and further considerations of projectile types at terrestrial craters

Details Identification of the projectile at the Brent crater, and further considerations of projectile types at terrestrial craters Identification of the projectile at the Brent crater, and further considerations of projectile types at terrestrial craters

Dec 1981

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1981gecoa..45.2417p&link_type=abstract

Geochimica et Cosmochimica Acta, vol. 45, Issue 12, pp.2417-2424

Other

16

Scientific paper

Impact melt samples from drill hole B1-59 at the 3.8 km diameter Brent crater (Ontario) have been analysed for siderophile trace elements indicative of meteoritic contamination. Samples from the basal melt zone at 823-857 m depth are enriched in Ir, Os, Pd, Ni, Co, Cr and Se over basement, with the abundance pattern suggesting a chondritic projectile for Brent. From a Ni-Cr correlation of 10 melt samples an L or LL chondrite is inferred. The contribution of an ultramafic country rock (alnoite) in the melt is too small to significantly influence its Ni / Cr ratio. Glass-rich breccias from the allochthonous breccias filling the crater also contain a meteoritic component. Interelement ratios (e.g. Ni / Cr ) are, however, fractionated relative to the melt zone samples. This, as well as the low Au content of all Brent samples, is probably a product of alteration. Additional data on impact melts from the 65 km diameter crater Manicouagan still did not reveal a meteoritic component, as also for the Mistastin crater (28 km diameter) where Cr analyses set an upper limit of 1% of an achondritic projectile component in the melt. Irghizites (tektite like glasses) from the Zhamanshin impact structure have been found to contain high Ni and Co concentrations, and our data show that Ir is also enriched. It is however not possible to define the projectile-type. Enrichment of an Ivory Coast tektite in Ir is confirmed. There are large differences in siderophile element concentrations among tektites, with otherwise similar chemical composition. There are now four known craters formed by chondrites (Clearwater East, Lapparjärvi, Wanapitei, and Brent), with Brent being the smallest of these. For smaller craters the projectiles appear to be limited to iron or stony-iron meteorites, because of atmospheric destruction of relatively small stony meteorites. It appears, however, that all major classes of meteorites are represented among the projectiles at terrestrial impact craters.

Affiliated with

Also associated with

No associations

Rating

Identification of the projectile at the Brent crater, and further considerations of projectile types at terrestrial craters does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Identification of the projectile at the Brent crater, and further considerations of projectile types at terrestrial craters, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Identification of the projectile at the Brent crater, and further considerations of projectile types at terrestrial craters will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1262772