Antarctic Meteorite Newsletter, Volume 22, No. 2 - August 1999
Volume 22, No. 2 - August 1999

Natural Thermoluminescence (NTL) Data for Antarctic Meteorites

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

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 levels below that which can reasonably be ascribed to long terrestrial ages. Such meteorites have had their TL lowered by heating within the last million years of so by close solar passage, shock heating, or atmospheric entry, exacerbated in the case of some achondrites 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).

Sample Class Natural TL
[krad at 250° C]

QUE97014

EUC

14± 4

QUE97053

EUC

12± 1

QUE97001

How

3.3± 0.3

QUE97002

How

10.4± 0.5

QUE97030

H3.4

32± 1

QUE97006

H5

66± 4

DEW96600

H6

28.5± 0.4

MET96506

H6

31.8± 0.4

MET96520

H6

70.5± 0.7

QUE97008

L3.4

5± 2

MET96515

L3.5

12± 1.0

QUE97034

L4

42.7± 0.5

MET96507

L5

67± 1

MET96510

L5

67.6± 0.1

MET96513

L5

66.2± 0.5

QUE97007

L5

89± 1

QUE97022

L5

35.8± 0.3

QUE97031

L5

23.8± 0.2

QUE97039

L5

84.7± 0.3

QUE97047

L5

46± 3

QUE97048

L5

4± 1

EET96021

L6

24.7± 0.1

MET96509

L6

59± 1

MET96511

L6

10.9± 0.1

MET96512

L6

19.5± 0.1

MET96514

L6

45.9± 0.5

QUE97009

L6

93± 1

QUE97018

L6

2± 2

QUE97029

L6

9.4± 0.1

QUE97032

L6

37.6± 0.1

QUE97033

L6

10.3± 0.1

QUE97035

L6

2± 2

QUE97036

L6

6.6± 0.3

QUE97037

L6

5.8± 0.7

QUE97038

L6

12.1± 0.1

QUE97046

L6

41.9± 0.2

QUE97049

L6

7.5± 0.1

QUE97050

L6

8.6± 0.1

QUE97054

L6

48.3± 1.1

QUE97057

L6

13.1± 0.2

QUE97078

L6

7.2± 0.3

QUE97013

LL5

40.7± 0.3

QUE97015

LL5

10.4± 0.1

QUE97016

LL5

8.2± 0.1

QUE97017

LL5

3.5± 0.4

QUE97019

LL5

5.0± 0.5

QUE97020

LL5

2.8± 0.3

QUE97021

LL5

1.6± 0.2

QUE97024

LL5

6.1± 0.1

QUE97025

LL5

1.2± 0.3

QUE97026

LL5

65.9± 2.2

QUE97028

LL5

41.3± 0.2

QUE97040

LL5

1.4± 0.1

QUE97041

LL5

7.6± 0.1

QUE97042

LL5

0.7± 0.1

QUE97043

LL5

4.0± 0.3

QUE97045

LL5

10.7± 0.1

QUE97051

LL5

2.2± 0.9

QUE97052

LL5

8.0± 0.1

QUE97058

LL5

9.4± 0.6

QUE97059

LL5

7.9± 0.1

QUE97069

LL5

6± 2

QUE97070

LL5

0.5± 0.1

QUE97085

LL5

7.5± 0.5

QUE97086

LL5

12.3± 0.1

QUE97010

LL6

18± 2

QUE97011

LL6

7± 1

QUE97012

LL6

2± 2

QUE97023

LL6

21.4± 0.1

QUE97044

LL6

5.4± 0.1

The quoted uncertainties are the standard deviations shown by replicate measurements on a single aliquot.

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 sample descriptions.
    MET 96515 and QUE 97008 were classified as type 3.5 and 3.4, respectively (AMN 21:2 and AMN 22:1). Their TL sensitivities are similar to type 3.1 unequilibrated ordinary chondrites (Sears et al., 1991, Proc. Lunar Planet. Sci, 21, 493-512). It is possible these meteorites are highly shocked but only weak shock features were noted in QUE 97008 (AMN 22:1). Other meteorites with very low TL sensitivities and thus candidates for histories involving extensive shock processing are QUE 97010, QUE 97011, QUE 97012, QUE 07029, QUE 97033, QUE 97035, and QUE 97037.

    QUE 97030 is confirmed as type 3.4 by TL sensitivity (AMN 22:1).

    QUE 97014 and QUE 97053 have TL sensitivities similar to eucrites of petrologic type 5 in the classification system of Takeda et al. (1983, Proc. 8th Symp. Antarctic Meteor., 181-205) and Batchelor and Sears (1991, GCA, 55, 3831-3844). It is, however, possible that QUE 97053 has a low TL sensitivity due to shock processing (AMN 22:1).

Pairings suggested by TL data:

  • EUC: QUE 97053 possibly with QUE 97014 (Note, however, strong petrographic differences, AMN 22:1)
  • L3: MET 96515 with MET 96503 (AMN 22:1)
  • L5: MET 96510 and MET 96513 with MET 96507
  • L5: QUE 97022 with the QUE 90218 group (AMN 15:2 and 18:2)
  • L5: QUE 97039 with QUE 97007
  • L5: QUE 97048 with the QUE 90205 group (AMN 15:2)
  • L6: QUE 97033 with QUE 97029
  • L6: QUE 97018, QUE 97029, QUE 97033, QUE 97035, and QUE 97037 with the QUE 94202 group (AMN 19:2)
  • L6: QUE 97049 with QUE 97036
  • LL5: QUE 97017, QUE 97019, QUE 97020, QUE 97021, QUE 97024, QUE 97025, QUE 97040, QUE 97041, QUE 97043, QUE 97045, QUE 97051, QUE 97052, QUE 97059, QUE 97086 and possibly QUE 97069 with QUE 97016.
  • LL5: QUE 97028 with QUE 97013
  • LL6: QUE 97012 with QUE 97011