11:30-11:45 PRELIMINARY ANALYSIS OF THE LATE PLEISTOCENE LAKE SEDIMENTS DEPOSITED IN BARRINGER CRATER, COCONINO COUNTY, ARIZONA.
Owen Davis (Geosciences, University of Arizona) and David Kring (Lunar and Planetary Laboratory, University of Arizona).
Barringer Crater ("Meteor Crater") formed about 50,000 years ago
when a 50 m diameter iron-nickel meteorite struck the Coconino
Sandstone of the Colorado Platuea, creating 1.6 km diameter crater.
The crater was partially filled with impact breccia, which was
later covered by 20 - 30 m of lake sediment. The pollen
concentration of sample MCE 22799-2 is low (8203 grains/cc),
and the diversity of palynomorphs is low (24 types, 500 grain count).
Pine (Pinus) is the most abundant pollen type (64%) followed
by sagebrush (Artemisia, 11%). Most (75%) of the pine pollen
is diploxylon type (cf. P. ponderosa). The low concentration,
low diversity, and dominance by wind-dispersed pollen types
suggest that long-distance transport was responsible for most of
the pollen in the sediment, and that local vegetation was sparse.
The upland vegetation closest to the crater probably was a conifer
groveland, with stands of pine, spruce (Picea, 6%), fir
(Abies. 7%) and Douglas fir (Pseudotsuga, <1%)
scattered over a sagebrush steppe. Aquatic palynomorphs include
Botryococcus (37% of upland pollen sum) coenobia and
horsetail (Equisetum, 32%) spores.
http://www.geo.arizona.edu/anas/annualmeetings/geology02/odavis03.html
Direct effects of the impact may have extened 40 km beyond
the crater ~ 50,000 megatons TNT
The crater was partially filled with impact breccia, which was
later covered by 20 - 30 m of lake sediment.
Pollen samples were taken from tumulus surrounding crater and from
upper breccia and lower lake sediment.
