Natural Thermoluminescence (NTL) Data for Antarctic Meteorites

Paul Benoit and Derek Sears
Cosmochemistry Group
Dept. of Chemistry and Biochemistry
University of Arkansas
Fayetteville, AR 72701

The measurement and data reduction methods were described by Hasan et al. (1987, Proc. 17th LPSC E703-E709; 1989, LPSC XX, 383-384). For meteorites whose TL lies between 5 and 100 krad, the natural TL is related primarily to terrestrial history. Samples with NTL <5 krad have TL below that which can be reasonably ascribed to long terrestrial ages. Such meteorites have had their TL lowered by heating with the last million years or so by close solar passage, shock heating, or atmospheric entry, exacerbated in the case of certain mildly metamorphosed meteorites by anomalous fading. We suggest meteorites with NTL >100 krad are candidates for unusual orbital/thermal histories (Benoit and Sears, 1993, EPSL 120, 463-471).

SampleClassNTL [krad at 250° C]

GRO95517

EH3

8 ± 2
   

GRA95215

H4

48.5 ± 0.4

GRO95527

H4

0.4 ± 0.1

GRO95541

H4

1.4 ± 0.1
   

GRA95213

H5

27.2 ± 0.1

GRA95214

H5

83.5 ± 0.1

GRO95519

H5

3.4 ± 0.1

GRO95521

H5

47.6 ± 0.8

GRO95524

L5

0.1 ± 0.1

GRO95537

H5

3.9 ± 0.1

GRO95538

H5

73 ± 3
     

GRO95507

H6

32.6 ± 0.3

GRO95525

H6

95.2 ± 0.2
   

GRO95536

L3

132 ± 6

GRO95539

L3

< 1

GRO95502

L3

< 1

GRO95504

L3

< 1

GRO95512

L3

< 1

GRO95546

L3.8

3.8 ± 0.1
   

GRO95515

L4

139.8 ± 0.5
   

GRA95200

L5

39.6 ± 0.1

GRO95529

L5

78.9 ± 0.2

GRO95530

L5

37.2 ± 0.1

GRO95540

L5

0.5 ± 0.1
   

GRO95500

L6

19.5 ± 0.1

GRO95501

L6

12.0 ± 0.1

GRO95514

L6

15.0 ± 0.3

GRO95523

L6

0.1 ± 0.1

Comments: The following comments are based on natural TL data, TL sensitivity, the shape of the induced TL glow curve, classifications, and JSC and Arkansas group sample descriptions.

GRO95502, GRO95504, and GRO95512 were classified petrographically as type 3.5 (AMN 20:2). TL sensitivities of these meteorites are very low (~0.001 relative to Dhajala H3.8) compared to type 3.5 meteorites. These meteorites may be of type 3.0-3.1, or t hey might be highly shocked. Extensive shock features were not reported in the initial description.

GRO95536 is type 3.3.

GRO95546 is confirmed as type 3.8 (AMN 20:2).

  1. Pairings (Confirmations of pairings)

  2. TL data do not confirm pairing suggested in the Newsletter:

  3. Pairings suggested by TL data: