[meteorite-list] NWA CV3's and DI's

From: bernd.pauli at paulinet.de <bernd.pauli_at_meteoritecentral.com>
Date: 19 Dec 2006 13:26:57 UT
Message-ID: <DIIE.000000B200001342_at_paulinet.de>

Hi Jeff and List,

Maybe some of these references are helpful!

Cheers,

Bernd (again exposed to Aussie English ;-)


HEYMANN D. et al. (1986) Carbon in dark inclusions of the
Allende meteorite (Proc. Lunar Planet. Sci. 17th, 341-342).

HEYMANN D. et al. (1987) Carbon in dark inclusions
of the Allende meteorite (Meteoritics 22, 1987, 3-15):

Dark inclusions (DI's) are among the major petrographic components of the Allende
meteorite; the others being: a fine-grained matrix of predominantly olivine (near Fa50),
chondrules (usually Fe,Mg-rich; occasionally Ca, Al-rich), and irregular inclusions
(Clarke et at., 1970; Mason, 1975; Fruland et al., 1978). DI's have also been called
fine-grained xenoliths. Their dimensions can be millimeters, and even centimeters. The
larger DI's can usually be recognized easily on cut surfaces of the Allende meteorite
because they appear darker than their surrounding areas, and are often poor in
chondrules or large irregular inclusions. Nevertheless, there does not exist now a firm
visual definition of a DI.

Fruland, Clanton, and Walton (1977) recognized three types of DI's:

(1) a black fine-grained matrix with few clasts and rare chondrules,
(2) a discontinuous, black, fine-grained matrix with abundant clasts and chondrules, and
(3) densely packed clasts and chondrules with a small percentage of discontinuous interstitial matrix.

Fruland (1978) reports SEM petrography on two lensoidal DI's: both display sharp
boundaries with the lighter Allende matrix; one has an approximately 60 ?m wide, but
discontinuous rim of Ca-rich silicates. Fruland notes that these two DI's consist primarily
of silicates, metal, and sulfides, with grain sizes up to about 40 ?m; hence, coarser than
matrix. Fruland also notes: "Many clasts have a dark 'accretionary' halo." Fruland et al.
(1978) have studied six DI's of which two are type 1; one is possibly type 3; the others are type 2.

HUTCHISON R. (2004) Meteorites: A Petrologic, Chemical, and
Isotopic Synthesis (Cambridge Planetary Science Series, pp. 506, p. 92):

Dark inclusions or matrix lumps are present in the members of a number of groups of the
carbonaceous chondrites. The inclusions are mm-sized, may be chondrule- and CAI-free
and generally are phyllosilicate-rich with magnetite and sulfide and are more aqueously
altered than matrix. These characteristics most closely resemble CI chondrites.

BISCHOFF A. et al. (1988), The chemical composition of dark inclusions
from the Allende meteorite (abs. in Lun.Plan. Sci. 19, 88-89).

C.A.Johnson, M. Prinz, M.K. Weisberg (1990) Dark inclusions in Allende, Leoville
and Vigarano: Evidence for nebular oxidation of CV3 constituents (GCA 54, 819-830).

P.C. Buchanan et al. (1996) Petrology of Allende
dark inclusions (abs. Meteoritics 31, 1996, A023).

BRENKER F.E. et al. (2002) Evidence for a high temperature episode during
multistage alteration of Allende dark inclusions (MAPS 37-7, 2002, July, A024).

KROT A.N. et al. (1999) Mineralogy, petrography, bulk chemical, iodine-xenon,
and oxygen-isotopic compositions of dark inclusions in the reduced CV3 chondrite
Efremovka (MAPS 34-1, 1999, 067-089).

KROT A.N. et al. (2002) Two-stage asteroidal alteration
of the Allende dark inclusions (MAPS 37-7, 2002, A082).

BIRYUKOV V.V. et al. (1998) Textures and bulk chemistry of dark inclusions
in the reduced CV3 chondrite Efremovka (Meteoritics 33-4, 1998, A014).

BIRYUKOV V.V. et al. (1998) Mineralogy and classification of dark inclusions
in the reduced CV3 chondrite Efremovka (Meteoritics 33-4, 1998, A015).

C.A.Johnson, M. Prinz, M.K. Weisberg (1990) Dark inclusions in Allende, Leoville
and Vigarano: Evidence for nebular oxidation of CV3 constituents (GCA 54, 819-830).

OHNISHI I. et al. (2000) Dark inclusions in the Mokoia CV3 chondrite: Record
of aqueous alteration, thermal metamorphism, and shock metamorphism
(MAPS 35-5, 2000, Suppl., A122).

OHNISHI I. et al. (2002) Dark inclusions in the Mokoia CV3 chondrite: Evidence
for aqueous alteration and subsequent thermal and shock metamorphism
(MAPS 37-12, 2002, pp. 1843-1856).
Received on Tue 19 Dec 2006 08:26:57 AM PST