Clinton Iron ore

Bill Payne, my good and caring friend who is always looking for a good
mystery, had written:

> -----Original Message-----
> From: asa-owner@lists.calvin.edu [mailto:asa-owner@lists.calvin.edu]On
> Behalf Of bpayne15@juno.com
> On 11/15/03 you said on this thread: "The Clinton is an iron-rich oolite,
> clearly marine. The iron may have been a local source off of the old
> Taconian Mtns." When I was in school (late 60's) I seem to remember that
> there was no explanation for the origin of the iron ore in the Clinton,
> or what we in AL call the Red Mountain formation. As you know, the
> Clinton goes from AL to NY, and contains "billions" of tons of ore. My
> old text (Longwell, Flint and Sanders, Phyiscal Geology, 1969, p 586)
> says: "It is believed that the iron was dissolved from iron-bearing
> minerals in mafic igneous rocks, carried by streams to the shallow sea
> (perhaps as a bicarbonate), and there precipitated as oxides." Is there
> a modern analog for this type of iron deposit, or is this another case
> where things in the past were different?
>

While doing research on something else, I ran into this which explains the
Clinton:

"An unconsolidated submarine deposit of iron ooids and pisoids, located
offshore the volcanic island Mahengetang, Indonesia, is described herein.
The deposit occurs in a shallow-marine setting, in an area characterized by
venting of hydrothermal fluids and expulsion of gas across the
sediment-water interface. The ooid deposit is essentially pure to a minimum
depth of 0.5 m and covers an area of at least 1000 m2 Ooids are composed of
concentric accretionary layers of limonite admixed with amorphous silica,
precipitated around andesitic rock fragments. The smallest layers forming
the ooids are about 10 [microns] in thickness. The iron-rich precipitate is
~50% iron by weight. Ooid formation is likely promoted by precipitation of
iron and silica from exhalative fluids rising up through the substrate."
Jeffrey M. Helkoop et al, "Modern Iron Ooids from a Shallow-Marine Volcanic
Setting: Mahengetang, Indonesia," Geology, 24(August 1996, ):759-762, p. 759

The Clinton is made of iron ooids just like that described above. It too is
a marine deposit, containing glauconite, a diagnositic marine mineral
(Franklyn B. Van Houten and Deba P. Bhattacharyya, "Phanerozoic Oolitic
Ironstones", Ann. Rev. of Earth & Planetary Sci., 1982, 10, (1982), p. 447.)
Received on Tue Dec 2 22:16:50 2003