Re: Roots in coal?

----- Original Message -----
From: <bpayne15@juno.com>
To: <glennmorton@entouch.net>
Cc: <asa@calvin.edu>
Sent: Monday, December 15, 2003 8:48 PM
Subject: Roots in coal?

>
> The main question I would like to ask Kevin is about tree roots in the
> coal itself. Kevin says trees didn't begin to grow until the mat built
> up. If Kevin has studied the microscopic structure of this coal, I would
> like to know if he commonly saw tree roots cross-cutting the banded
> structure of the coal. Indeed, I would like to know how banded coal
> could form at all if this was an intensely-rooted peat mat. Compaction
> will not transform crossscutting tree roots into horizontally-banded
> coal.

> If Kevin's J seam coal formed from trees growing on the peat mat, I would
> like to know if crosscutting tree roots were found in the banded coal.
> If so, can he furnish photos? I will predict that no such crosscutting
> relationship of roots and banded coal exist, which will be strong
> evidence that the coal was transported.

Hi Bill,

Here is another reference to roots within coal, this one from a seam which
correlates with the one in the photos and is located ~50 km away. It's
from:

Lamberson, M., Bustin, M., Kalkreuth, W. D. and Pratt, K. C. (1996): The
formation of inertinite-rich peats in the mid-Cretaceous Gates Formation:
implications for the interpretation of mid-Albian history of paleowildfire.
Palaeogeography, Palaeoclimatology, Palaeoecology, v. 120, Issues 3-4, March
1996, p. 235-260.

(referring to image analysis of a block sample of the seam) "A branched
gymospermous root structure is present in Fig. 11, and has been pyrolysed to
fusinite." From the caption to the figure: "Enlargement of area shown in a)
showing transeverse section of root structure. Small cell size and lack of
definition in annual growth pattern indicative of root origin". "..Majority
of block is inertinite."

Most petrographic work on coal is done using standard point counts, where
the coal is ground to 850 microns and cemented into a pellet. As you can
imagine, roots are hard to recognize. Block samples preserve the
macroscopic structure of the coal. The above example may or may not satisfy
your criterion for cross cutting roots, since we can't say with certainty
what the inertinite groundmass represented in the figure is. The authors
state that these coals are made up of "principally stem and root wood,
leaves and bark of gymnosperms, as well as the leaves and rhizomes of
ferns." (same reference). The parent vegetation is fundamentally different
than the Carboniferous coals which you have experience in. Banding in these
coals is not from bark layers as such.

Incidentally, I recall you emphasized in an earlier post that abundant bark
layers in Carboniferous coals supported an model of floating mats shedding
bark by abrasion (please correct me if I'm wrong on this). The reason why
there is so much bark in Carb. coals is because of the parent vegetation
(dominantly lycopods). "In lycopod stems the wood was, in contrast to the
bark, very thin and quantitativle small in amount, e.g. in Lepidodendron the
bark fills 90% of stems in cross section." (Stach's Textbook of Coal
Petrology, 3rd ed. 1982). So the coal is expected to be mostly bark if
formed in situ as well as in your model.

A couple of questions for you. For the Cretaceous seams in the photos:

What floating mat model are you favoring - a "grounded mat" model or a
"shedding mat" model? This has bearing on your explanation of the roots.

Are you proposing a marine setting for these coals?

Are you sticking with your criteria outlined in you Mr. 25, 1999 post for
falsifying the floating mat model (copied below)? Anything to add?

"to falsify the floating mat model, I would like to see
intensely and deeply rooted underclays with little or no interbedded
structure remaining, a gradational contact between the underclay and
coal, roots connecting to the last generation of stumps in the swamp, and
the last generation of stumps still standing in the coal where they grew."

Thanks,

Kevin

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Received on Thu Dec 18 08:15:01 2003