Engineering topics

Stoeffler, Dieter

Publications and source records attributed to Stoeffler, Dieter.

3 records

NASA NTRS1992

Shock metamorphism of carbonaceous chondrites

Shock effects were studied in 69 carbonaceous chondrites, including CM2, CO3, CV3, ungrouped C2-C4, and CK4-6 chondrites, using optical microscopy of thin sections. It is shown that the classification scheme of Stoeffler et al. (1991) for the progressive stages of shock metamorphism in ordinary chondrites is also applicable to carbonaceous chondrites. On the basis of shock effects in olivine, the 69 carbonaceous chondrites could be assigned to four shock stage, S1 to S4. The CM2 and CO3 groups were found to be the least shocked chondrite groups, whereas the CK4-6 and CV3 were the most strongly shocked groups.

Scott, Edward R. D.↗

NASA NTRS1991

Shock metamorphism of ordinary chondrites

This study proposes a revised petrographic classification of progressive stages of shock metamorphism of 26 ordinary chondrites. Six stages of shock (S1 to S6) are defined on the basis of shock effects in olivine and plagioclase as recognized by thin section microscopy, and the characteristic shock effects of each shock stage are described. It is concluded that shock effects and the sequence of progressively increasing degrees of shock metamorphosis are very similar in H, L, and LL groups. Differences in the frequency distribution of shock stages are relatively minor. It is suggested that the collisional histories of the H, L, and LL parent bodies were similar. Petrologic type-3 chondrites are deficient in stages S4 and S6 and, with increasing petrologic type, the frequency of stages S4 to S6 increases. It is suggested that the more porous and volatile-rich Type-3 chondrites are subject to melting at a lower shock pressure than the nonporous chondrites of higher petrologic type. Stage S3 is the most abundant in nearly all petrologic types.

Stoeffler, Dieter↗

NASA NTRS1988

Loss of radiogenic argon from shocked granitic clasts in suevite deposits from the Ries Crater

Five granite clasts from the Otting and Aumuehle quarries in the suevite ejecta deposits from the Ries Crater, Germany, were characterized with respect to modal composition, the degree of shock, and the loss of radiogenic Ar. The results were used to estimate the relative fractions of total crater volume, which were characterized by undisturbed K-Ar ages, partly reset ages, and essentially complete gas loss. The results suggest that the loss of Ar form the Ries suevite samples occurred in a 'hot' post-impact ejecta layer. It was estimated that less than 50 percent of the material composing the hot Ries ejecta should show at least partially reset K-Ar ages; such materials compose no more than 5 percent of the total displaced crater volume.

Bogard, Donald↗