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Breccias resembling melt bombs from the Roter Kamm Crater
Author(s) -
Degenhardt J. J.,
Miller R. McG.,
Reimold W. U.,
Reid A. M.
Publication year - 1996
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.1996.tb02079.x
Subject(s) - breccia , impact crater , geology , shock metamorphism , geochemistry , ejecta , clastic rock , quartz , metamorphism , petrology , geomorphology , paleontology , astrobiology , sedimentary rock , physics , quantum mechanics , supernova
Irregular, dark green to black, glassy‐looking boulders are locally common in the northwest portion of the rim of the Roter Kamm impact crater in southern Namibia. Their smooth surfaces, flow‐like textures, presence of folds, and their similarity to melt bombs have led to the interpretation that these are molten impact ejecta. However, the samples we have examined are all fine‐grained breccias composed of angular fragments that show no evidence of melting. Meltlike surface textures of these rim breccias are largely a consequence of surface wind polishing of fine‐grained rocks in a desert environment. These mono‐mict breccias were produced by impact‐related brecciation of Gariep sediments (carbonaceous, siliceous shales) previously modified by low‐grade Damaran metamorphism. Secondary quartz within the breccias is attributed to fluid activity that postdates the impact.