Re: Canadian Coal - depositional setting

----- Original Message -----
From: "Bill Payne" <bpayne15@juno.com>
To: <ksharman@pris.bc.ca>
Cc: <asa@calvin.edu>
Sent: Sunday, February 08, 2004 3:53 PM
Subject: Re: Canadian Coal - depositional setting

> Hi Kevin,
>
> Couple of quick questions from this post.
>
> On Wed, 28 Jan 2004 17:47:36 -0700 "Kevin Sharman" <ksharman@pris.bc.ca>
> writes:
>
> > "In the Five Cabin Creek area, type 1 channel deposits occur above
> nearshore
> > marine deposits of the Sheriff Member (the shoreface sand - KS)...type
> 1
> > channel deposits consist of fine- to coarse-grained pebbly sandstones
> and
> > conglomerates..the conglomerates are massive and clast supported, with
> a
> > sandstone matrix and are poorly sorted. Pebbles in the conglomerates
> are
> > rounded and 0.5 cm to 2 cm in diameter..some of the sandstones contain
> > mudstone pebbles and rip-up clasts. Coal spar is fairly common."
>
> "Coal spar" is a term with various meanings. Can you please
> define/describe coal spar? Is this use to describe calcite-filled joints
> in coal clasts?
Coal spar is irregular pieces of coaly material found in sandstones and
conglomerates. It is interpreted as ripped up pieces of peat/vegetation,
much like rip-up clasts of mudstone are.
>
> > In other words, a fluvial channel, which has cut into the peat swamp at
> some
> > point as evidenced by coal spar. The basal coal is missing; the
> sandstones
> > and conglomerates rest directly on the shoreface sandstone. He notes
> rapid
> > lateral facies changes, characteristic of a fluvial environment.
>
> Can you offer any description of the contact between the fluvial-channel
> walls and the coal? I would like to know if the fluvial sediments
> interfinger with or are gradational with the coal, and, if not, then how
> steep are the contacts as measured from what would have been horizontal
> at the time of deposition?
Carmichael didn't have the contact between channel lithologies and the coal
exposed where he described the rocks above. Erosional channels I have seen
cutting coal in other places have sharp contacts which can dip up to maybe
10 degrees.

>
> Bill
>
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Received on Mon Feb 9 00:57:30 2004