Fired glaciofluvial sediment in the northwestern Andes: Biotic aspects of the Black Mat

Fired glaciofluvial beds in outwash considered to date from the onset of the Younger Dryas Event (~ 12.9 ka) in the northwestern Venezuelan Andes are considered equivalent to the Black Mat deposits described in other areas of North and South America and Europe. It may be equivalent to sediment recov...

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Bibliographic Details
Published in:Sedimentary geology 2011-05, Vol.237 (1), p.73-83
Main Authors: Mahaney, William C., Krinsley, David, Langworthy, Kurt, Kalm, Volli, Havics, Tony, Hart, Kris M., Kelleher, Brian P., Schwartz, Stephane, Tricart, Pierre, Beukens, Roelf
Format: Article
Language:English
Subjects:
Asteroids
Bacteria associated with fired sediment
Chemistry of the Black Mat
Concentration (composition)
Diagenesis of the fired material
Earth Sciences
Equivalence
Feldspars
Geomorphology
Glassy carbon
Heating
Quartz
Sciences of the Universe
Sediments
Signatures
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Summary:Fired glaciofluvial beds in outwash considered to date from the onset of the Younger Dryas Event (~ 12.9 ka) in the northwestern Venezuelan Andes are considered equivalent to the Black Mat deposits described in other areas of North and South America and Europe. It may be equivalent to sediment recovered from other sites containing beds with spikes of cosmic nuclides and charcoal indicating the presence of widespread fire, one of the signatures of the Black Mat conflagration that followed the proposed breakup of Comet Encke or an unknown asteroid over the Laurentide Icesheet at 12.9 ka. In the northern Andes at Site MUM7B, sediment considered coeval with the Black Mat contains glassy carbon spherules, tri-coatings of C welded onto quartz and feldspar covered with Fe and Mn. Monazite with excessive concentrations of REEs, platinum metals including Ru and Rh, possible pdf's, and disrupted/brecciated and microfractured quartz and feldspar from impacting ejecta and excessive heating summarize the data obtained so far. The purpose of this paper is to document the physical character, mineralogy and biotic composition of the Black Mat.
ISSN:0037-0738
1879-0968
DOI:10.1016/j.sedgeo.2011.02.005