NetNews Usenet Archive 1992 #27/NN_1992_27.iso/spool/sci/geo/geology/2445

Text File | 1992-11-21 | 1.8 KB | 35 lines

Newsgroups: sci.geo.geology
Path: sparky!uunet!gatech!mailer.cc.fsu.edu!geomag!cain
From: [e-mail] (Joe Cain)
Subject: Re: life, Moon and geology
Message-ID: <[e-mail]>
Sender: [e-mail] (Usenet News File Owner)
Nntp-Posting-Host: geomag.gly.fsu.edu
Organization: Florida State University Geology Dept.
References: <[e-mail]> <[e-mail]> <[e-mail]>
Date: Sun, 22 Nov 92 05:18:56 GMT
Lines: 22

In article <[e-mail]> [e-mail] (DANIEL M. DEOCAMPO) writes:
>In article <[e-mail]>, [e-mail] writes...

>>It is doubtful that the CO2 would have preciptated as carbonate.  Even
>>today large amounts of calcium carbonate shell/skeletal matter never
>>makes it to the bottom, dissolving on the way down.  The level below
>>which the carbonates dissolve is known by a number of names, such as
>>carbonate compensation depth.

Although the above discussions revolved around the question of how the
CO2 initially very high in Earth's Hadean atmosphere decreased to the
some 200-300 ppm prior to 1600 (it is now about 360 ppm), a paper in
the August Geology by Brad Opdyke and another author from the U. of
Michigan modeled the CO2 during the fluctuations in sealevel between
150K years ago and present. They found that the CO2 levels observed in
the Vostok ice cores could be matched by their estimates in the
reactions of organisms in coastal environments. I believe they took
into account the total interchange in deep ocean and atmosphere as
well. This would seem to imply that the amount of shallow seas is the
important factor.
Joseph Cain        [e-mail]
[e-mail]        scri::cain