Chixulub and K/T boundary

[boneill@shell.com]

 On Feb 7, Michael wrote:

>  I have been told that papers "soon to be released" will claim
>that a close examination of some of the sediments from drillholes
>into the Chixulub crater area shows Cretaceous marine layers
>_on top of_ the impact breccia.  I guess that the layers are dated
>by forams.
>  Can anyone provide further details of the sediment studies?
>If not, we'll have to wait for the papers to appear, I guess --
>I was told to watch geological journals, not Nature/Science...
 
 A paper on this subject was given at the GSA meeting in Boston, Oct
1993 (A.A. Meyerhoff and J.B. Lyons).  A short "opinion" column giving
the pertinant details appeared in Geology in January 1994 (v. 22, no.1
 p. 3-4) by  A.A. Meyerhoff, J.B. Lyons and C.B. Officer).

The paper attributes the Chicxulub structure to volcanic
origin (andesite and bentonitic breccia) overlain by  350 m of
Late Cretaceous sediments (Maastrichtian and middle Campanian).
This is based on the Yucatan No. 6 well drilled on the stucture
in 1966. (unpublished well log and cuttings analysis).

 It stills seems to be very controversial with both sides (volcanic vs.
asteroid) certain that they are correct.  My impression is that the
asteroid group has more members, but that doesn't necessarily make it
correct.

  Brian

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