>There is an interesting article on fossil pollen reportedly found in the
>Hakatai shale in Grand Canyon. it can be found at:
>
>http://www.rae.org/pollen.html
>
>This was written in reply to criticism by S.S. Tell me what you think.
>
>Allen Roy
Allen,
I was only able to get and read the file you mention above, the 3 articles
in vols. 22 and 23 of the CRS Quarterly, and the 1973 letter to the editor
in Geotimes [vol 18(June) p. 9-10]. None of the other articles (including
Burdick's original) are available here in the U. of Iowa library. Since I
do not know much about the geology of the Grand Canyon and haven't read all
the articles, there isn't much I can say.
I do think that with all the searching for evidence of life in Precambrian
rocks of the world it is curious that only those involved with CRS have been
able to find Cenozoic pollen (and fungal debris) in rocks of those ages. I
also find it curious that since some samples appear to have pollen and
others do not that they did not do a systematic study to find out how common
and where the pollen is in the Hakatai Shale. (I noticed also that the
research is really only published in the CRS Quarterly -- hardly a journal
refereed by other palynologists).
It is also curious that pollen would be found in red shales -- usually red
indicates weathering in an oxygen rich environment and oxygen is one of the
few things that destroys pollen exine. But then I don't know anything about
the Hakatai Shale besides that it is Precambrian in age, has units with mud
cracks and ripples, and is reddish.
I personally would have gone much deeper into the shale than 3-4 inches as I
am sure, even in Arizona, weathering process are extending into the rock
further that.
I have a couple of questions from reading though: what were the pollen
counts (number of grains) found in the samples? Were the pollen grains
silicified or not? (I have left Holocene samples in HF for days without
degradation), how did they check the rock samples to eliminate the
possibility of microfractures, and since this all started in one of the best
palynology labs in the country (at the University of Arizona) did they do
any follow up studies to find how the samples "were contaminated?"
Seems to me that the palynologists at Arizona would want to know where that
pollen came from.
In another post Glenn mentioned the presence of igneous intrusions in the
formation. Pollen and spores would not be destroyed by the intrusions
except in the area of extreme contact metamorphism. As an aside, some
palynologists, who have worked with oil companies, have told me they use the
color of the pollen grains as a guide for temperature history and maturation
of the hydrocarbons, in fact some oils and coals contain original pollen and
spores.
I have the color temperature chart in one of my textbooks, and I believe
pollen could survive temperatures at the depths Glenn mentioned even with
igneous intrusions.
Glenn is right that pollen analysis is not applicable to much of the oil
industry, especially those involving marine deposits. This is not my area of
palynology I'm a Quaternary scientist by training, but palynologists study
other palynomorphs beside pollen and many paleopalynologists would have as
much difficulty distinguishing modern pollen types as I would fungal
remains, algal cysts, Paleozoic spores, and acritarchs (check out Traverse's
_Paleopalynology_). Those people are primarily working (if they have jobs)
with the oil industry (Chevron, Shell, etc.).
John