The thermoluminescence carrier in the Dhajala chondrite
by Sparks, M. H.; McKimmey, P. M.; Sears, D. W. G.
The thermoluminescence (TL) sensitivities of 58 chondrules sepd. from the Dhajala (H3.8) chondrite were measured to study the cause of the 105-fold variation in the TL sensitivity of ordinary chondrites. The TL sensitivites of the individual chondrites are 0.002-0.12 (where 4 mg of bulk Dhajala powder = 1), with no correlation with chondrule mass, cross-sectional area, or diam. Some chondrules have TL per unit mass 10 times that of bulk Dhajala powder, and mass-TL balance arguments suggest that these chondrules are a mjaor TL carrier. The compn. of 15 chondrules was also detd. showing that high TL chondrules tend to have Ca contents at the upper end of the range obsd. These observations are consistent with the TL sensitivity variation in ordinary chondrites, which is related to metamorphism, being caused by the devitrification of glass to produce feldspar and with feldspar being the dominant TL phosphor in Dhajala. That chondrules are an important TL carrier would also be consistent with primary feldspar as the TL phosphor, but petrol. observations make this appear unlikely.