[meteorite-list] Meteorites in limestone - Example from Sweden

From: Mark Ferguson <mafer_at_meteoritecentral.com>
Date: Thu Apr 22 10:28:19 2004
Message-ID: <01f301c388a3$c60a0ca0$6701a8c0_at_vs.shawcable.net>

Hi Robert
Not sure I have close to all the answers, but metal, free metal, in a
limestone, can only be from a few select sources. One, the first to mind, is
vents such as black smokers. But, here we have high temps, a corrosive
environment, and no discoloration of the limestone from other vent
chemicals. Not a likely source. Second to mind are some very nasty bacteria
which excrete free metals while digesting rock for nutrient, and are a
possible source for gold and silver crystals (least thats some peoples
thoughts). Next to mind is the free iron found in basalts, not basalt in the
limestone, doubtful then that is the source. Iron and nickel, which shows a
Widmanstätten pattern, cannot be from any of these sources and is not known
from any terrestrial souce to date. Best guess would be a impactor and the
metal nuggets are splash ejecta which landed on a reef or in a oolitic
environment and got encapsulated as the limestone was buried.
Mark
----- Original Message -----
From: "Robert Szep" <zeprox_at_albedo.net>
To: <meteorite-list_at_meteoritecentral.com>
Sent: Wednesday, October 01, 2003 9:19 PM
Subject: [meteorite-list] Meteorites in limestone - Example from Sweden


> Hello Paul and list...
>
>
> I have found IRON NODULES in ~500 million year old limestone and know
where
> to find more.
> They are rather smooth and not, repeat NOT badly 'rusted'.
>
> The limestone surrounding the small pocket left behind after removing the
> metal-object shows some discoloration but only in very close proximity to
> where the nodule was.
> The metal in this limestone is far from abundant but then again I didn't
> hammer my way through any major amount of host material. At the time I
> thought the dense, roughly 1/2 inch nuggets might be meteorites but
figured
> the odds were slim.
> After reading your posting I realized the odds might not be nearly as slim
> as I originally considered them to be.
>
> Here is my question to you and the 'list'...
> When a small metal object is found in ~500 million year old limestone,
what
> are the chances of that object being a meteorite?
>
> Replies to this posting, if any, should be interesting.
> If the consensis is better than 50/50 I might collect a few specimens this
> weekend.
>
>
> Best regards, Robert Szep.
>
>
> ----- Original Message -----
> From: "Paul" <lenticulina1_at_yahoo.com>
> To: <meteorite-list_at_meteoritecentral.com>
> Sent: Wednesday, October 01, 2003 10:40 PM
> Subject: [meteorite-list] Unconventional Meteorite Hunting - Example from
> Sweden
>
>
> >
> > It seems like there are some unconventional places
> > that people can look for meteorites. For example,
> > ancient meteorites have been found in the carbonate
> > rocks of Sweden as discussed in:
> >
> > Schmitz, B. Peucker-Ehrenbrink, Lindstrom, M., and
> > Tassinari, M., 1997, Accretion Rates of Meteorites
> > andCosmic Dust in the Early Ordovician. Science.
> > vol. 278, no. 5335, pp. 88-90.
> >
> > In this paper they discussed "Abundant fossil
> > meteorites" that were found in "...marine,
> > condensed Lower Ordovician limestones..."
> >
> > They note:
> >
> > 1. A 4-inch in diameter meteorite discovered
> > middle Ordovician Limestone in 1951, which was
> > described by Thorslund and Wickman (1981).
> >
> > 2. a swedish meteorite , called "Osterplana 1," which
> > was discovered in 5-million year older Lower Ordovician
> > limestone about 300 miles away from the above by Hansen
> > and Berstrom (1997).
> >
> > Twelve more meteorites have been found at the Thorsberg
> > Limestone Quarry. Hansen and Berstrom (1997, pp. 3)
> > stated:
> >
> > "A 10-foot-thick section of the
> > Holen ("Orthoceratite") Limestone,
> > of Early Middle Ordovician age, is
> > extracted at the Thorsberg quarry
> > and sawed into thin slabs that are
> > used for windowsills and floor tile.
> > Quarry workers discarded slabs with
> > impurities, such as the meteorites,
> > until Professor Maurits Lindstrom
> > of the University of Stockholm
> > alerted them to save such slabs.
> > The 12 specimens were recovered
> > between 1992 and 1996. Ten of the
> > specimens were recovered from a
> > 2-foot-thick bed of limestone and
> > may represent a single meteorite
> > fall. The other three specimens were
> > recovered from two separate levels
> > above this layer. Seven of the
> > specimens, collected between 1993 and
> > 1996, are from a quarried limestone
> > volume of no more than about 127,000
> > cubic feet. Most of the specimens are
> > now on display at the Stiftelsen Paleo
> > Geology Center in Lidkoping, Sweden."
> >
> > The meteorites found in the Thorsberg Quarry meteorites
> > range in size from about 0.5 to 3.5 inches in diameter.
> > They have been almost completely replaced by calcite and
> > barite. The meteorite masses are dark reddish brown and
> > look like iron nodules surrounded by a zone of lighter
> > colored limestone.
> >
> > It would be fun to look at correlative condensed sections,
> > in the United States and elsewhere for similar fossil
> > meteorites. If there was a period of increased meteorite
> > influx during the Ordovician, meteorites should findable
> > in the Untied States as well as Sweden.
> >
> > Additional and Cited References
> >
> > Hasen, M. C., and Bergstrom, S. M.. 1997, Ancient
> > meteorites. Ohio Geology, Spring 1997.
> >
> > Nystrom, J. O., and Wickman, F. E., 1991, The Ordovician
> > chondrite from Brunflo, central Sweden; II, Secondary
> > minerals. Lithos. vol. 27, no. 3, pp. 167-185.
> >
> > Nystrom, J. O., Lindstrom, M., and Wickman, F. E., 1988,
> > Discovery of a second Ordovician meteorite using
> > chromite as a tracer. Nature. vol. 336, pp. 572-574.
> >
> > Schmitz, B., Lindstrom, M., Asaro, F., and Tassinari, M.,
> > 1996, Geochemistry of meteorite-rich marine limestone
> > strata and fossil meteorites from the Lower Ordovician
> > at Kinnekulle, Sweden. Earth and Planetary Science
> > Letters. vol. 145, pp. 31-48.
> >
> > Thorslund, Per, and Wickman, F. E., 1981, Middle
> > Ordovician chondrite in fossiliferous limestone from
> > Brunflo, central Sweden. Nature. vol. 289, pp. 285-286.
> >
> > Thorslund, Per., Wickman, F. E., and Nystrom, J. O.,
> > 1984, The Ordovician chondrite from Brunflo, central
> > Sweden, I. General description and primary minerals.
> > Lithos. vol. 17, pp. 87-100.
> >
> > Another person, Andrew A. Sicree of the Earth and
> > Mineral Sciences Museum at Pennsylvania State University
> > is looking for meteorites in coal deposits. Web pages
> > and pdf files discussing his efforts can be found at:
> >
> > FINDING FOSSIL METEORITES:
> > http://www.meteorite.com/psu_find.htm
> >
> > Researchers Seek Meteorites In Coal Mines
> > http://www.psu.edu/ur/NEWS/SCIENCETECH/meteorite.html
> >
> > POTENTIAL FOR PRESERVATION AND RECOVERY OF FOSSIL
> > IRON METEORITES FROM COAL, TRONA, LIMESTONE, AND
> > OTHER SEDIMENTARY ROCKS.
> > http://www.lpi.usra.edu/meetings/metsoc97/pdf/5057.pdf
> >
> > There are likely various unorthodox places where
> > people might hunt for meteorites.
> >
> > Yours,
> >
> > Paul
> > Baton Rouge, LA
> >
> >
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>
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Received on Thu 02 Oct 2003 01:11:55 AM PDT