Shock Effects in Experimentally Shocked Samples of the H6 Chondrite Kernouve

Details Shock Effects in Experimentally Shocked Samples of the H6 Chondrite Kernouve Shock Effects in Experimentally Shocked Samples of the H6 Chondrite Kernouve

Jul 1993

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1993metic..28..431s&link_type=abstract

Meteoritics, vol. 28, no. 3, volume 28, page 431

Computer Science

6

Kernouve, Olivine, Shock, Troilite

Scientific paper

Introduction: A new classification of shock metamorphism in chondrites has recently been published [1]. This classification scheme, which is based on a microscopic investigation of shock effects in olivine and plagioclase, was calibrated using shock recovery experiments with single crystals and natural rocks. In the past, only a few shock experiments have been made with ordinary chondrite material [2-4]. Here, we report the first results of shock experiments using the H6 chondrite Kernouve. Kernouve is one of the best examples for an unshocked ordinary chondrite and results of previous shock experiments are also available for this meteorite [4]. Experimental methods: Sample disks (diameter: 13 mm, thickness: 0.5 mm) of Kernouve (provided by B. Zanda, Paris) were used for shock-loading experiments at room temperature and pressures of 10, 15, 20, 35 and 60 GPa. The experimental set-up with a high-explosive-driven flyer plate was described earlier by [5]. Microscopic Shock Effects: Olivine of the unshocked chondrite shows sharp extinction and some irregular fractures. Olivine in the experimentally shocked samples displays the following pressure dependent features: Irregular fractures (10-60 GPa); undulatory extinction (10-20 GPa); planar fractures (10-60 GPa); weak mosaickism with a domain size of 25 micrometers diameter (10-20 GPa); strong mosaickism with a domain size of 5 micrometers (20-60 GPa); planar deformation features (20-60 GPa); and staining (60 GPa). The abundance of planar fractures in olivine decreases with increasing shock pressure from 94% in the 10-GPa sample to 14% in the 60-GPa sample. Well- developed planar deformation features (PDFs) were found in the 35-GPa sample. PDFs and planar fractures both display a similar orientation. In contrast to natural PDFs [1], PDFs in olivine grains from experimentally shocked Kernouve samples are shorter (up to 20 micrometers) and weakly bent. Plagioclase of the unshocked sample is characterized by sharp extinction. In the pressure range from 10 to 20 GPa, plagioclase displays undulatory extinction. In the 35-GPa sample most of the plagioclase is transformed to maskelynite (diaplectic glass). This transformation is complete in the 60-GPa sample. The first effects of localized shock-induced melting are observed in the 35- GPa sample, where a few melt pockets occur. The 60-GPa sample shows abundant melt pockets, shock veins, and troilite injections into fractures of the silicates. Troilite of the unshocked sample is monocrystalline. In the pressure range from 10 to 20 GPa, troilite shows undulatory extinction and twinning. The 35- and 60-GPa samples contain only recrystallized troilite. This troilite is polycrystalline and consists of equant grains with 120-degree angles between grain boundaries. Shock Classification and Conclusions: Using the classification scheme of [1], the experimentally shocked Kernouve samples can be classified into the following stages: Unshocked--S1; 10 GPa--S3; 15 and 20 GPa--S4; 35 GPa--S5; and 60 GPa--S6. The transition between shock stage 3 and 4 appears to be somewhat lower than proposed by [1] and occurs in the pressure range of 10 to 15 GPa, probably near to 15 GPa.The investigation of the experimentally shocked chondrite Kernouve shows the same pressure-dependent features as observed in naturally shocked ordinary chondrites [1]. For this reason shock recovery experiments provide an important basis for a better understanding of natural shock features in ordinary chondrites. References: [1] St"ffler D. et al. (1991) GCA, 55, 3845-3867. [2] Bogard D. D. et al. (1987) GCA, 51, 2035-2044. [3] Dai C.-D. et al. (1991) Chin. Sci. Bull., 36, 1984-1988. [4] Sears D. W. et al. (1984) GCA, 48, 343-360. [5] M ller W. F. and Hornemann U. (1969) EPSL, 7, 251-264.

Affiliated with

Also associated with

No associations

Rating

Shock Effects in Experimentally Shocked Samples of the H6 Chondrite Kernouve does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Shock Effects in Experimentally Shocked Samples of the H6 Chondrite Kernouve, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Shock Effects in Experimentally Shocked Samples of the H6 Chondrite Kernouve will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1072415