AW: AW: AW: [meteorite-list] Amgala, Tsarev and Zag

From: Jörn Koblitz <koblitz_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:52 2004
Message-ID: <E5E6112EA31FA24CB448E091C6883C050EBB78_at_server2000.microfab.de>

Below is a table of H/L chondrites as found in MetBase. Yamato 8424 is =
NOT a member of the H/L group, but a polymict breccia mainly of H clasts =
in an LL host. For unequilibrated H/L3 chondrites, it is not easy to =
identify them as being members of this transitional group since their =
average fayalite and ferrosilite compositions tend to shift to lower =
values. A typical feature of unequilibrated chondrites (Fa/Fs percentage =
mean deviations (PMD) increase, mean values decrease)

Joern
MetBase

name class Fall? country date TKW kg breccia shock weathering fa_avg =
fs_avg latitude longitude=09
Bremerv=F6rde H/L3.9 Y Germany 1855/05/13 7,25 Y S2 W0 18.6 53=B024'N =
9=B06'E=09
Dar al Gani 369 H/L3.5 N Libya 1997/10/20 1,001 S2 W3 16.8 9.1 =
27=B056.92'N 15=B054.08'E=09
Dar al Gani 378 H/L3 N Libya 1997/10/21 0,068 S3 W2 14.3 7.9 =
27=B054.97'N 15=B050.27'E=09
Dar al Gani 591 H/L6 N Libya 1998/03 0,09 S2 W3 20.0 17.4 27=B039.32'N =
15=B059.54'E=09
Dhofar 428 H/L5 N Oman 2001/03/28 0,526 S2 W4 21.5 18.5 18=B047.394'N =
54=B029.311'E=09
Tieschitz H/L3.6 Y Czech Republic 1878/07/15 28 S3 W0 49=B036'N =
17=B07'E=09
Y 74645 H/L4 N Antarctica 1974/12/28 0,0356 C 21.1 17.9 71=B030'S =
35=B040'E=09
Y 8424 H/L/LL N Antarctica 1984 0,00946 Y 23.1 17.0 71=B030'S =
35=B040'E=09
Y 9405 H/L4 N Antarctica 1994/12 0,00483 71=B032'49"S 35=B024'07"E=09




> -----Urspr=FCngliche Nachricht-----
> Von: j.divelbiss_at_att.net [mailto:j.divelbiss@att.net]
> Gesendet: Freitag, 19. M=E4rz 2004 04:40
> An: Adam Hupe
> Cc: meteorite-list_at_meteoritecentral.com
> Betreff: Re: AW: AW: [meteorite-list] Amgala, Tsarev and Zag
>=20
>=20
> Adam and others,
>=20
> What do we know about H/L's beyond what Joern said? =20
> Bernd...you gave us some thought on the H/L
> NWA 1955. You seemed very intrigued by what you saw. Any comments.
>=20
> If you ever saw Haxtun in thin section...it is very strange=20
> indeed. To me it is one of the
> coolest(as in awesome) thin sections I've ever seen.
>=20
> More on H/L's would be good.
>=20
> John
> > Hi John and group,
> >=20
> > I enjoyed the reading when I returned this afternoon. I=20
> was unaware that
> > polymict breccia chondrites were rarer than regolithic=20
> breccias. I guess
> > there is always room to learn something new and when the=20
> List is used
> > properly it can provide educational gems such as this. I=20
> think the term
> > transitional is used to describe an H/L classification. =20
> This means to me
> > that the chondrite came from a completely different parent=20
> body than an H or
> > an L therefore it is not the mixing of two parent bodies. =20
> Since I never
> > studied the H/L designation and only a few exist there is=20
> room here for
> > something to be learned.
> >=20
> > Sounds like an interesting subject,
> >=20
> > Adam
> >=20
> >=20
> > ----- Original Message -----
> > From: <j.divelbiss_at_att.net>
> > To: "J=F6rn Koblitz" <koblitz_at_microfab.de>
> > Cc: <Meteorite-list_at_meteoritecentral.com>
> > Sent: Thursday, March 18, 2004 5:51 PM
> > Subject: Re: AW: AW: [meteorite-list] Amgala, Tsarev and Zag
> >=20
> >=20
> > > Joern,
> > >
> > > Thanx a lot for the great answers. I think many will=20
> benefit from this
> > exchange.
> > > I know Adam will be happy that you helped his cause to=20
> highlight the
> > uniqueness of the polymict chondrite feature of Amgala. Now=20
> we'll wait for
> > those results...How about it Adam?
> > >
> > > Couldn't the H/L's get mixed together in space to create a
> > polymict...seems reasonable, even if we don't have a good example
> > yet...maybe Amgala will be just that.
> > >
> > > Regards,
> > > John
> > > > Dear John,
> > > >
> > > > I think, for chondrites, regolith breccias (monomict or=20
> genomict) are
> > quite more
> > > > abundant than polymict breccias. The opposite is true=20
> for achondrites.
> > Polymict
> > > > breccias, especially eucrites (howardites are polymict=20
> by definition!)
> > are quite
> > > > often polymict (there is an unusual high fraction of=20
> polymict eucrites
> > from
> > > > Antarctica), whereas regolith breccias are rather=20
> common only for
> > lunaites (e.g.
> > > > anorthositic highland breccias), which are - by definition -
> > achondrites. A nice
> > > > example for another regolithic achondrite is the=20
> howardite Kapoeta
> > (higly
> > > > solar-gas-rich material).
> > > >
> > > > Regarding the H/Ls (Bremervoerde, NWA 1955,=20
> Tieschitz...): these aren't
> > polymict
> > > > breccias containing H and L lithologies, but members of a group
> > intermediate
> > > > between H and L chondrite in terms of composition and isotopic
> > signatures. They
> > > > likely come from a parent body (PB) distinct from the=20
> PBs of both, the L
> > and H
> > > > chondrites. Though they are breccias, they are not=20
> mixing products of L
> > and H
> > > > material.
> > > >
> > > > Best wishes,
> > > > Joern
> > > >
> > > >
> >=20
> ______________________________________________________________
> ______________
> > ___
> > > > Joern Koblitz
> > > > MetBase Editor
> > > > The MetBase Library of Meteoritics and Planetary Sciences
> > > > Benquestrasse 27
> > > > D-28209 Bremen, Germany
> > > > phone: +49 421 24 100 24
> > > > fax: +49 421 24 100 99
> > > > email: info_at_metbase.de
> > > >
> >=20
> ______________________________________________________________
> ______________
> > ___
> > > >
> > > >
> > > >
> > > >
> > > > > -----Urspr=FCngliche Nachricht-----
> > > > > Von: j.divelbiss_at_att.net [mailto:j.divelbiss@att.net]
> > > > > Gesendet: Dienstag, 16. M=E4rz 2004 19:44
> > > > > An: J=F6rn Koblitz
> > > > > Cc: bernd.pauli_at_paulinet.de;=20
> Meteorite-list_at_meteoritecentral.com
> > > > > Betreff: Re: AW: [meteorite-list] Amgala, Tsarev and Zag
> > > > >
> > > > >
> > > > > Joern,
> > > > >
> > > > > Thanx for the clarification on regolith versus the basic
> > > > > breccia types.
> > > > >
> > > > > As far as chondrites go...is a genomict breccia with a
> > > > > regolith history like Zag more or less unusual when compared
> > > > > to a polymict breccia for chondrites, as in the supposed case
> > > > > for Amgala? I ask this since you did point out that
> > > > > achondrites are the ones that usually have the polymict
> > > > > breccias, and not chondrites.
> > > > >
> > > > > Does this make NWA 1955 (H/L 3-4) a polymict breccia also? Or
> > > > > does its classification as being unequilibrated chondrite
> > > > > make it different than a breccia per say?
> > > > >
> > > > > John
> > > > >
> > > > > > Tsarev noble gas data data:
> > > > > >
> > > > > > he_3 he_4 ne_20 ne_21 ne_22 ar_36 ar_38 ar_40
> > > > > > 1,58 121 0,54 0,54 0,60 0,42 0,11 575
> > > > > > 2,07 108 0,78 0,82 0,88 0,83 0,20 1635
> > > > > > all values: x 10E-8 cc STP/g
> > > > > >
> > > > > > Reference: Herzog G. F., Vogt S., Albrecht A., Xue S., Fink
> > > > > D., Klein J.,
> > > > > > Middleton R., Weber H. W. and Schultz L. (1997) Complex
> > > > > exposure histories for
> > > > > > meteorites with "short" exposure ages. Meteoritics=20
> 32, 413-422.
> > > > > >
> > > > > > According to this, Tsarev isn't a regolith breccia.
> > > > > >
> > > > > > BTW: A regolith breccia can be either polymict (different
> > > > > source types of
> > > > > > clasts, e.g., H3 + L6), xenolithic (some minor exotic
> > > > > (non-host type) clasts,
> > > > > > e.g. CM clasts in L6 host), genomict (same material type
> > > > > but different
> > > > > > petrologic grades, e.g. H3 + H5), or monomict (e.g. light
> > > > > H3 + dark H3
> > > > > > (irradiated) lithologies). Usually, regolith breccias are
> > > > > monomict or genomict
> > > > > > breccias. Achondrites are often polymict breccias (e.g.
> > > > > howardites, eucrites,
> > > > > > diogenits, ureilites, lunaites).
> > > > > >
> > > > > > Regards,
> > > > > > Joern
> > > > > >
> > > > > >
> > > > > ______________________________________________________________
> > > > > _________________
> > > > > > Joern Koblitz
> > > > > > MetBase Editor
> > > > > > The MetBase Library of Meteoritics and Planetary Sciences
> > > > > > Benquestrasse 27
> > > > > > D-28209 Bremen, Germany
> > > > > > phone: +49 421 24 100 24
> > > > > > fax: +49 421 24 100 99
> > > > > > email: info_at_metbase.de
> > > > > >
> > > > > ______________________________________________________________
> > > > > _________________
> > > > > >
> > > > > >
> > > > > >
> > > > > > > -----Urspr=FCngliche Nachricht-----
> > > > > > > Von: bernd.pauli_at_paulinet.de=20
> [mailto:bernd.pauli_at_paulinet.de]
> > > > > > > Gesendet: Montag, 15. M=E4rz 2004 21:20
> > > > > > > An: Meteorite-list_at_meteoritecentral.com
> > > > > > > Betreff: [meteorite-list] Amgala, Tsarev and Zag
> > > > > > >
> > > > > > >
> > > > > > > Adam wrote:
> > > > > > >
> > > > > > > > I do not believe it is going to classify as a
> > > > > > > > regolith breccia but rather a polymict breccia.
> > > > > > >
> > > > > > > Adam also wrote:
> > > > > > >
> > > > > > > > I thought one distinction made for a regolith=20
> breccia is that
> > > > > > > > there are signs of crystal damage caused by the=20
> solar wind
> > > > > > >
> > > > > > > Martin A. chirped:
> > > > > > >
> > > > > > > > Tsarev which is brecciated but not polymict
> > > > > > > > is also altered by solar winds, isn't it?
> > > > > > >
> > > > > > > Hello Adam, Martin, and List,
> > > > > > >
> > > > > > > There are 3 types of inert and/or noble gases in=20
> some meteorites:
> > > > > > >
> > > > > > > (1) those produced by cosmic ray bombardment (cosmogenic);
> > > > > > > (2) those resulting from radioactive decay of elements
> > > > > (radiogenic)
> > > > > > > in the meteorite;
> > > > > > > (3) those present originally (=3D trapped or=20
> primordial gases).
> > > > > > >
> > > > > > > No. (3) is what we are interested in to find out=20
> if Amgala, Tsarev
> > > > > > > and Zag have or have not been altered by solar=20
> wind particles.
> > > > > > >
> > > > > > > These gases are 4^He, 20^Ne, 36^Ar, 84^Kr, 132^Xe.
> > > > > > >
> > > > > > > There are two different sources for these=20
> inert/noble gases:
> > > > > > >
> > > > > > > (a) solar-type gas
> > > > > > > (b) planetary-type gas
> > > > > > >
> > > > > > > To find out "what is what" and "which is which",=20
> meteoriticists
> > > > > > > consider the relative amounts and, above all,=20
> ratios of a number
> > > > > > > of isotopes.
> > > > > > >
> > > > > > > J.T. Wasson proposed the following arbitrary
> > > > > > > definition of a solar gas-rich meteorite:
> > > > > > >
> > > > > > > - The 20^Ne/22^Ne ratio should be greater than 2.5
> > > > > > > - Ne isotopic data should plot above the dashed line
> > > > > > > you find on p. 102 and on p. 111 of Wasson's and
> > > > > > > Sears' books (see: Reference)
> > > > > > > - The 4^He content should exceed 2 x 10^-5 cm^3 g^-1
> > > > > > > - The 20^Ne / 36^Ar ratio should be greater than 0.3
> > > > > > >
> > > > > > > Unfortunately, I don't have any of these isotope=20
> data handy for
> > > > > > > Tsarev :-( What I do have are some 3^He and 21^Ne=20
> data from
> > > > > > > the MPI Mainz but they are of little help at the moment).
> > > > > > >
> > > > > > > There is an abstract paper by Honda et al. but=20
> they only discuss
> > > > > > > cosmogenic nuclides (see: Reference) - again of=20
> little help.
> > > > > > >
> > > > > > > Anyway, Tsarev is a special case and as such=20
> mentioned in a
> > > > > > > research article by S.K. Vogt et al. The authors=20
> group Tsarev
> > > > > > > with a number of other H and L chondrites that underwent a
> > > > > > > complex "two-stage exposure history":
> > > > > > >
> > > > > > > t1 =3D 8 million years, radius ca. 200 cm
> > > > > > > t2 =3D ca. 0.3 million years, radius ca. 140 cm
> > > > > > >
> > > > > > >
> > > > > > > Best wishes,
> > > > > > >
> > > > > > > Bernd
> > > > > > >
> > > > > > >
> > > > > > > References:
> > > > > > >
> > > > > > > VOGT S.K. et al. (1993) On the Bur Ghelulai H5=20
> chondrite and other
> > > > > > > meteorites with complex exposure histories=20
> (Meteoritics 28,
> > > > > > > 1993, 71-85).
> > > > > > >
> > > > > > > HONDA M. et al. (1992) Cosmogenic nuclides in the
> > > > > > > Tsarev chondrite (Meteoritics 27-3, 1992, 234-235).
> > > > > > >
> > > > > > > WASSON J.T. (1974) Meteorites Classification and=20
> Properties
> > > > > > > (Springer-Verlag, Berlin, Heidelberg, New York,=20
> pp. 97-109).
> > > > > > >
> > > > > > > SEARS D.W. (1978) The Nature and Origin of
> > > > > > > Meteorites (Adam Hilger Ltd. Bristol, pp. 110-115).
> > > > > > >
> > > > > > > McSWEEN H.Y. (1999) Meteorites and Their Parent Planets
> > > > > > > (Cambridge University Press, Glossary, pp. 41-44,
> > > > > 111-112, 244-248).
> > > > > > >
> > > > > > >
> > > > > > > ______________________________________________
> > > > > > > Meteorite-list mailing list
> > > > > > > Meteorite-list_at_meteoritecentral.com
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> > > > > > >
> > > > > >
> > > > > > ______________________________________________
> > > > > > Meteorite-list mailing list
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> > > > >
> > > >
> > > > ______________________________________________
> > > > Meteorite-list mailing list
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> > >
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> >=20
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Received on Fri 19 Mar 2004 09:10:58 AM PST