Thermoluminescence of Japanese Antarctic ordinary chondrite collection

Thermoluminescence (TL) data for Japanese Antarctic chondrites obtained by laboratories in Arkansas and Okayama were compared and found to be in good agreement. Data for three large Antarctic chondrites were used to develop new TL pairing criteria which were found to be less restrictive than previously used. These new criteria were applied to ten equilibrated and twenty-eight unequilibrated Japanese ordinary chondrites. The petrographic subtype of the forty-three unequilibrated ordinary chondrites were determined from their TL sensitivity and nine were found to have petrographic types under 3.3 and therefore are particularly primitive samples of solar system material

Thermoluminescence studies of ordinary chondrites in the Japanese Antarctic meteorite collection, II: New measurements for thirty type 3 ordinary chondrites

We have measured the thermoluminescence (TL) properties of thirty type 3 ordinary chondrites from the Japanese Antarctic meteorite collection. This brings to 73 the total number of Japanese type 3 ordinary chondrites examined in this way by the Arkansas-Okayama collaboration. Fifteen pairing groups were found using TL and geographical criteria. Most of the new meteorites are of petrologic types 3.6-3.9,but fourteen are of petrologic type ≤3.4. Six of the 73 meteorites (Yamato (Y)-790448,Y-793596,Y-793565,Y-791324,Y-791558,Y-74660) have petrographic types 3.5) tend to have higher induced TL peak temperature and peak width than those with low TL sensitivity, in confirmation of earlier work and consistent with peak temperature and width as well as TL sensitivity, being independent parameters of thermal history. Samples not obeying these trends (Y-75029,Y-86706,Y-793567 and Y-790787), are either heavily weathered or experienced atypical thermal histories

Red thermoluminescence of enstatite from the Chainpur meteorite

For most ordinary chondrites feldspar is mainly responsible for thermoluminescence [TL], but in type 3 ordinary chondrites, especially those which are most primitive, other minerals are important. We observed red TL with a ∿660nm spectral peak in an ordinary chondrite, Chainpur (LL3.4). The mineral responsible for the red TL was identified as iron-free enstatite. Spatial distribution of TL and cathodoluminescence [CL] for the same specimen was also investigated, and it was found that the red TL areas corresponded to the high-sensitivity areas of red CL

Thermoluminescence of chondrules in primitive ordinary chondrites,Semarkona and Bishunpur

The spatial distribution of the induced thermoluminescence (TL) and TL glow curves of the primitive ordinary chondrites, Semarkona (LL3.0) and Bishunpur (LL3.1), were investigated over a wide range of wavelengths using a TL spatial distribution readout system. Although bulk samples of Semarkona and Bishunpur have very low TL sensitivity, individual chondrules show a wide variety of induced TL intensity and glow curve shape. Chondrules with anorthite-normative mesostases have especially high induced TL intensity, and their TL is produced at wavelengths >480nm, compared with <480nm for the sensitivity range of the usual TL measuring systems. Some of the metamorphism-dependent TL sensitivity of type 3 ordinary chondrite therefore results in changes in the spectrum of the light produced

The Cali meteorite fall: A new H/L ordinary chondrite

10 pages, 6 figures, 5 tablesThe fall of the Cali meteorite took place on 6 July 2007 at 16 h 32 ± 1 min local time (21 h 32 ± 1 min UTC). A daylight fireball was witnessed by hundreds of people in the Cauca Valley in Colombia from which 10 meteorite samples with a total mass of 478 g were recovered near 3°24.3'N, 76°30.6'W. The fireball trajectory and radiant have been reconstructed with moderate accuracy. From the computed radiant and from considering various plausible velocities, we obtained a range of orbital solutions that suggest that the Cali progenitor meteoroid probably originated in the main asteroid belt. Based on petrography, mineral chemistry, magnetic susceptibility, fhermoluminescence, and bulk chemistry, the Cali meteorite is classified as an H/L4 ordinary chondrite brecciaThis work was partially supported by NASA Cosmochemistry grants NNH05AB65I to JNG and NNG06GF95G to AER and NASA Discovery Data Analysis grant NNX08G17G to DWGS. JMTR also thanks CSIC for a JAE-Doc research contractPeer Reviewe