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An investigation by transmission electron microscopy of planar deformation features in naturally shocked quartz
Author(s) -
Goltrant Olivier,
Doukhan JeanClaude,
Cordier Patrick,
Courtillot Vincent
Publication year - 1992
Publication title -
terra nova
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.353
H-Index - 89
eISSN - 1365-3121
pISSN - 0954-4879
DOI - 10.1111/j.1365-3121.1992.tb00829.x
Subject(s) - quartz , geology , shock metamorphism , transmission electron microscopy , planar , shock (circulatory) , metamorphism , annealing (glass) , mineralogy , geochemistry , materials science , paleontology , meteorite , physics , composite material , nanotechnology , medicine , astronomy , computer science , computer graphics (images)
We have investigated by Transmission Electron Microscopy (TEM) the planar deformation features(PDF) in quartz from various sites where shock metamorphism has been detected optically: impact sites; the Vredefort complex (South Africa) and the K/T boundary at Raton Basin (Colorado). PDFs are straight narrow bands of glass or microtwins or huge densities of dislocations. Such contrasting microstructures must reflect different shock scenarios. In the Vredefort complex the post‐shock thermal history has strongly overprinted the shock‐induced defects. In the Raton Basin samples very tiny bubbles have precipitated on the dislocations, strongly suggesting a lengthy annealing at moderate pressure and temperature. This new information should be taken into account in any model of the origin of the K/T transition. In any case, observation of PDFs by optical microscopy alone is not sufficient to unambiguously conclude on their origin.