Brazos river comment and reply

Comments (here below) to the Reply by Gerta Keller, Thierry Adatte, Gerald Baum, Zsolt Berner, a reply to Comment by Schulte et al., Earth and Planetary Science Letters (2008) in press, doi: 10.1016/j.epsl.2007.12.025

6. Omission of Evidence?

Schulte et al. criticize our Brazos research paper on the basis that it is not a review paper and therefore omitted evidence "in and outside the Gulf of Mexico" that would support their viewpoint. Specifically, they claim "more than 24 recent ODP K-P drillcores all provide strong support for the genetic relationship between the Chicxulub impact event and the worldwide distributed K-P boundary ejecta layer" and conclude "Yet, Keller and her co-workers prefer to keep ignoring nearly{3} all of it." There is a powerful irony in this accusation when they referenced not a single paper of our Chicxulub studies{1} [2]. We did not ignore their papers. Over the past 10 years we have written several review papers [8-10, 30, 31] and discussed their evidence and interpretations, as well as numerous research reports on over 45 K-T sequences with impact spherules. As for their claim, there are, in fact, not 24 drill-cores, but only three (Bass River, Blake Nose and Demara Rise [14-16] that juxtapose Chicxulub spherules and Danian sediments. Rather than a genetic link, this juxtaposition appears to be due to condensed sedimentation and erosion as reviewed in Keller [31]. Curiously, for none of these sections has high-resolution quantitative faunal analyses been published, which is necessary to determine how complete the sections are.{2} Until such studies are published, these sections cannot be considered evidence for the "genetic link" claimed by Schulte et al. [2]. Moreover, the condensed records of deep-sea or terrestrial sections cannot be considered as more complete than the high sedimentation records of continental shelf and slope areas.

1} that is not neccesary, because these Chicxulub papers (and other review papers) keep repeating the same erroneous statements, including the most important one, the misidentification of dolomite crystals as foraminifers.

2} But these sections do contain complete cyclostratigraphic sequences, down to the precession cycle. We rather prefer complete sections with lower sedimentation rates, than the disturbed sections in the Gulf of Mexico to demonstrate completeness

3} One fact also consistently ignored or arm-waved away by Keller et al is the occurrence of the amalgamated dual layer in the majority of coal-swamp deposits. In these coal-swamp deposits (in particular Red Deer River, Canada; Brownie Butte, Montana; Dogie Creek, Wyoming; Madrid railroad, Colorado and Raton Basin, New Mexico) the Chicxulub spherule bearing ejecta is juxtaposed to the iridium, shocked quartz and shocked zircon bearing layer. As the shocked zircon has the tell tale signature of the Pan-African basement of the Chicxulub impact, the genetic link between the Chicxulub impact and the KT ejecta layer is beyond doubt established.