Re: US Pennsylvanian Coal - depositional setting

From: Kevin Sharman <ksharman@pris.bc.ca>
Date: Wed Apr 14 2004 - 01:43:06 EDT

----- Original Message -----
From: "Bill Payne" <bpayne15@juno.com>
To: <ksharman@pris.bc.ca>
Cc: <asa@calvin.edu>
Sent: Tuesday, April 13, 2004 9:08 PM
Subject: Re: US Pennsylvanian Coal - depositional setting

> > The example shows that the substrate doesn't have roots when they
> >looked at
> > it. The real question is "Did the substrate ever have roots?" In
> >other
> > words, did the substrate have roots when the peat was being
> >established, the
> > roots bioturbated the substrate, and now they are not visible, or did
> >the
> > peat establish without rooting of the substrate? If you say that the
> >roots
> > were there, and now they're not, I will use this to explain ancient
> >examples
> > of substrates with no roots. If you say the roots were never there, I
> >will
> > use this to back up my contention that the roots didn't need to
> >penetrate
> > the substrate. Your modern example isn't helping you.
>
> To say "that the roots didn't need to penetrate the substrate" ignores
> examples I have photographed of grass and trees with roots which
> penetrate the substrate. Some of these are coming your way tonight.

No it doesn't. You have quoted a modern swamp example from Indonesia with
no roots in the substrate, correct?
"Trees in the mixed peat-swamp forest and pole
forest...have spreading, buttressed, and prop roots, which are generally
confined to a root mat 50-80 cm thick at the top of the peat and do not
penetrate to the deeper peat or mineral sediments below thick peat."
(from Neuzil, S.G., Supardi, Cecil, C.B., Kane, J.S., Soedjono, K., 1993.
Inorganic geochemistry of domed peat in Indonesia and its implication for
the origin of mineral matter in coal. Modern and Ancient Coal-Forming
Environments, GSA Special Paper 286, 25.)

So we have an Indonesian example with NO ROOTS in the substrate, and your
Alabama example with ROOTS penetrating the substrate. With me so far? So,
from this we can conclude that some swamps have roots in the substrate and
some don't. Swamps like the Indonesian example show that having roots
penetrating the substrate is not a necessary part of a modern swamp.
Understand? So roots didn't NEED to penetrate the substrate. Got it?
>
> I say the roots were never there, and you say you "will use this to back
> up my [your] contention that the roots didn't need to penetrate
> the substrate."
>You may say whatever you wish, but you are running
> counter to my photos when you say "roots don't need to penetrate the
> substrate." Roots, grass as well as tree roots, do penetrate the
> substrate - for nutrients and for support, even in the flooded conditions
> of the swamps I have photographed for you.

Yes, they do, as shown in your photos, but you CAN have a swamp without
roots in the substrate, like the Indonesian example.
>
> > > Would you agree that these rootless
> > > coal seams are allochthonous?
>
> > In a word, no. See my discussion above about lack of roots below
> seams.
> > The seams with no roots could be hypautochthonous, with peat
> transported
> > within the swamp. If this is the case, they should be high in mineral
> > matter and inertodetrinite. Or they could be from the attached
> floating
> > mats Glenn mentioned. These appear to be of limited extent, as they
> > normally fringe the edge of lakes and abandoned channels, and they can
> be
> > considered in situ (not transported).
>
> How many square miles would rootless coal seams have to cover before you
> would admit that they are not of "limited extent"?

Bill, you need to read these posts more carefully. The phrase "limited
extent" refers to attached floating mats. Hypautochthonous seams can cover
large areas, just as large as the swamps themselves. These would result in
rootless coal seams.

Kevin
Received on Wed Apr 14 01:44:09 2004

This archive was generated by hypermail 2.1.8 : Wed Apr 14 2004 - 01:44:09 EDT