Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin?

Details Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin? Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin?

Dec 2008

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008agufm.p31a1382c&link_type=abstract

American Geophysical Union, Fall Meeting 2008, abstract #P31A-1382

Physics

1000 Geochemistry, 1600 Global Change, 5420 Impact Phenomena, Cratering (6022, 8136)

Scientific paper

An enigmatic carbon-rich black layer, of possible worldwide occurrence, is interpreted to indicate an extraterrestrial impact around 12.9 ka, a period coeval with the Younger Dryas (YD) environmental changes (Firestone et al. 2007, PNAS 104). This interpretation is based on the possible identification of a series of markers postulated to be of impact origin, such as magnetic grains and microspherules, charcoal, soot, C- spherules, nanodiamonds, fullerenes with extraterrestrial He and elevated concentrations of Ir. Among these markers, only the elevated Ir concentration is a non-ambiguous impact indicator. In early 2007, one of us (PC) measured the concentration of platinum group elements (including Ir) in 4 samples of this black layer. Allen West provided the samples along with their Ir concentrations. The samples originated from Howard Bay, NC (level HB-11D2) and Blackwater Draw, NM (levels BW-DT, D/C and BW-B/A), and were supposed to contain 15 ng/g Ir (<150 micron magnetic fraction), 2.0 ng/g Ir (bulk sediment), 2.25 ng/g Ir (bulk sediment) and <0.1 ng/g Ir (bulk sediment) respectively. In Table 1 of Firestone et al. (2007) the Blackwater Draw sample contains 2.3 ng/g Ir, and the separated magnetic fraction rises up 24 ng/g. The obtained results showed that none of the 4 samples yielded PGE concentrations above 0.5 ng/g. Considering the attention the claim of a possible YD impact has generated in the last year, we are currently reanalyzing these 4 samples of the black layer using high precision NiS fire-assay preconcentration combined with ICP-MS analyses. On proven crater melt rocks or impact layers, the quantitation limits reach: 0.06 ng/g Ru, 0.01 ng/g Rh, 0.14 ng/g Pd, 0.06 ng/g Ir, and 0.1 ng/g Pt, far below the Ir values claimed by Firestone et al. (2007). In addition, these 4 samples are being analyzed for Os isotopes, known to be most sensitive for the detection of minute amounts of extraterrestrial components (%<%%<%0.05 wt%) in impact layers. The results of these new analyses will confirm or not the extraterrestrial origin of the Younger Dryas C-rich black layer.

Affiliated with

Also associated with

No associations

Rating

Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin? 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 Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Do The Concentrations Of Platinum Group Elements In The Younger Dryas Black Layer Really Support An Extraterrestrial Origin? will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1237057