Geology Reference
In-Depth Information
Wisconsin Glacier (WSG) 95300
H3.3 chondrite
2733 g
Found December 24, 1995
14.0 × 10.0 × 9.0 cm
Weathering = A/B
Low-petrologic-grade ordinary chondrites are rare but contain many
interesting features due to their unequilibrated nature. Because the level of
postnebular thermal heating is low, many minerals and chemical features
are preserved in these samples, making them a treasure trove of astro-
materials. Presolar grains, pristine chondrules, isotopic heterogeneities,
and organic compounds are among the rare components preserved in
low-grade chondrites.
A
WSG95300,0
oliv
cpx
mes
opx
B
CI
CM
CM (H)
CR
CV
CO
OC
TL+WIS
EC
WSG 95300
11000
9000
7000
5000
Bells
3000
Sem
1000
-1000
0.0
0.2
0.4
H/C (at.)
0.6
0.8
1. 0
Plate 1
MiNERALogy
SigNiFiCANCE
WSg 95300 contains numerous chondrules (up to 1.8 mm
across), chondrule fragments, and mineral grains in a
dark matrix containing a moderate amount of nickel-
iron and troilite. The meteorite is essentially unweath-
ered. olivine and pyroxene is of variable composition:
olivine, Fa
1-21
; pyroxene, Fs
2-17
.
WSg 95300 is a low-petrologic-grade H chondrite (3.3),
which are rare and contain a variety of very important com-
ponents (e.g., organics (left, [3]), presolar grains) that may
not survive metamorphism to higher temperatures that are
so common among ordinary chondrites. Pristine chondrule
textures led to using WSg 95300 as a basis for experimental
studies aimed at duplicating chondrule textures. These
studies propose that Type 1B chondrule textures (right, top
[1]) can be explained by 20%-30% partial melting of
chondritic materials (right bottom, [1]), with main variables
being peak temperature, time of heating, and cooling rate.
References [1-3]
