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?

>
> We agree that there are roots below the J seam of coal. I contend that
> the roots are transported, as evidenced by the upside-down roots, even
> dispersal of intermittent roots, and the common plane of termination of
> several roots. Kevin maintains that the "dozens if not hundreds of fine
> roots" override my evidence. We agree that the fine roots go in and out
> of the plane of the rock face, but if these roots were in situ I would
> like to see more of a pattern, similar to the "radiating" roots. We
> should also see more of the parent plants to which the fine roots were
> attached. The radiating roots seem to be thicker than the fine roots we
> had been discussing, and therefore may be from a different type of plant.
> The photo with "Big root" appears to have several "shrub" roots that are
> upside down (branching upward).
>
> The main objection I have to these intervals (Kevin's J seam and the seam
> near my office) being in situ is the small number of preserved roots. At
> the rate of 1 to 2 mm per year for the accumulation of peat in a swamp
> (swamps include trees, marshes are grass and shrubs only - no trees), I
> can't imagine that only a few roots would be preserved in the uppermost
> soil horizon. The radiating roots in the photo with the finger pointing
> to the root mass are well over a foot long. For the peat mat to get over
> a foot thick (too thick for the roots to penetrate into the underlying
> soil) at the rate of 1 to 2 mm/yr would take 30 to 60 years. With even
> as little as 30 years of grass and shrub growth we should see a solid
> mass of roots, not individual roots separated by sandy zones with no
> roots. Therefore the evidence suggests that these roots were
> transported.

We won't agree on this one if you have expectations like that. When you are
shown roots which look identical to ones that grow in place today, you say
there aren't enough of them. You specify (in an older post) "intensely and
deeply rooted underclays" as a criterion which will convince you of in-situ
coal formation. This allows you to reject these as not intensely rooted
enough.
>
> The radiating pattern can certainly be maintained during transportation;
> this only requires that the plant be uprooted with the roots still
> attached, which can easily happen in wet soil. Since the root end is
> heavier, the plant settles out of suspension with the roots down and gets
> buried in growth position.
>
> 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.

Remember that bituminous coal is a metamorphic rock. The coal proceeds
through a stage known as gelification which obscures the original textures.
The coal precursors for these seams include large (up to 20 cm diameter)
trees, as evidenced by log impressions in an overlying channel sandstone.
Just as no macroscopic remnants of these logs are found in these coals, no
macroscopic evidence of roots is found either - they have been coalified
into (predominantly) vitrinite. These coals contain 50% to 60% vitrinite.

the upper lithotype sample contains a small
> collotelinite fragment oriented perpendicular to the bedding, which may
> represent a rootlet, and as such might signify pedogenesis. However, no
> further evidence exists to support this." (Glasspool, Ian J. 2003.
> Hypautochthonous-allochthonous coal deposition in the Permian, South
> African, Witbank Basin No. 2 seam; a combined approach using
> sedimentology, coal petrology and palaentology. International Journal of
> Coal Geology, v 53, Issue 2, pp 81-135, p 22 of 36)
>
> Glasspool is grasping at straws to describe a single crosscutting
> fragment "which may represent a rootlet", in an effort to retain some
> indication that this coal seam might be somewhat in situ. IMO, roots
> crosscutting sand or shale bedding planes may or may not be in situ since
> the sediment could settle down around the roots. However, roots
> crosscutting or penetrating sheets of bark would (I think) have to be in
> situ since a sheet of bark could not settle down around rootlets that
> penetrate the bark.
>
> 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.

See above - you are making an unwarranted leap by saying that banded coals
without roots imply transportation.

However, roots in coal are documented in the literature. Stach's Handbook
of Coal Petrology (1982) has this to say: "Humic colloidal solutions or gels
form preferentially through oxidation of peat and brown coal in the presence
of abundant water, e.g. around roots whose surfaces have functioned as
water-conducting channels and oxygen carriers in the peat. Thus, broad
partings of eugelinite can be observed around the roots of Sequoia stumps in
the Cologne brown coal." (p. 239, 3rd edition).

Your turn :)

Kevin Sharman
>
> Bill
>
> ________________________________________________________________
> The best thing to hit the internet in years - Juno SpeedBand!
> Surf the web up to FIVE TIMES FASTER!
> Only $14.95/ month - visit www.juno.com to sign up today!
>
Received on Tue Dec 16 01:21:16 2003