Petrology of Apollo 15 black-and-white rocks 15445 and 15455 - Fragments of the Imbrium impact melt sheetThe paper describes two macroscopically similar black-and-white rocks, 15445 and 15455, which were collected from the rim of Spur Crater on the Apennine Front. The two Apollo 15 rocks are very similar in chemistry and clast population, but the matrix of 15455 is finer grained than that of 15445. The 15445 sample contains a lithic clast assemblage of plutonic/metamorphic spinel troctolite, troctolite, norite, and anorthosite, and its fine-grained vesicular black coherent matrix consists of a melt-bonded aggregate of small mineral clasts which are mainly olivine, plagioclase, and pink spinel. The two rocks are distinct from any other large samples from the Apollo 15 site. It is suggested that the rocks are samples of an impact melt sheet which forms a bedrock unit of the Apennine Front, and that this melt sheet did not form in a local small-scale event but was produced during the Imbrium impact event.
Document ID
19780057758
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Ryder, G. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Bower, J. F. (Harvard College Observatory and Smithsonian Astrophysical Observatory, Center for Astrophysics, Cambridge Mass., United States)