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Stratigraphy of Ejecta from the Lunar Crater Aristarchus

1973; Geological Society of America; Volume: 84; Issue: 9 Linguagem: Inglês

10.1130/0016-7606(1973)84 2.0.co;2

1943-2674

J. E. Guest,

Space Exploration and Technology

Research Article| September 01, 1973 Stratigraphy of Ejecta from the Lunar Crater Aristarchus J.E. GUEST J.E. GUEST 1University of London Observatory, Mill Hill Park, London NW7 2QS England Search for other works by this author on: GSW Google Scholar Author and Article Information J.E. GUEST 1University of London Observatory, Mill Hill Park, London NW7 2QS England Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1973) 84 (9): 2873–2894. https://doi.org/10.1130/0016-7606(1973)84 2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation J.E. GUEST; Stratigraphy of Ejecta from the Lunar Crater Aristarchus. GSA Bulletin 1973;; 84 (9): 2873–2894. doi: https://doi.org/10.1130/0016-7606(1973)84 2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Ejecta from lunar crater Aristarchus consist of mappable units that have different surface characteristics, lithologies, and geneses. Photogeologic mapping demonstrates that these units can be ordered into a stratigraphic succession representing stages in the emplacement of ejecta during a single impact event.Four main ejecta units are recognized: (a) a highly fractured rim unit consisting of an overturned flap of country rock, (b) a continuous ejecta blanket, (c) a zone of bright discontinous ejecta outside the continuous ejecta blanket associated with numerous secondary impact craters, and (d) a group of ejecta deposits on the rim which are genetically related to each other and include hummocky material (the hummocky rim unit), blocky lobes, and smooth flows. Other units, such as the ridged and leveed flows and the dark "lakes" or "playas," are relatively younger than the ejecta and are only briefly discussed.The continuous ejecta blanket lies stratigraphically above the rim unit. To the east and south, the ejecta blanket has been stripped off the overturned rim unit by outward flowage from the crater during ejecta production, leaving parts of the rim eroded bare. Fall of large missiles to form the secondary craters and bright ejecta preceded the emplacement of the continuous ejecta. The general asymmetry of the continuous ejecta-blanket distribution appears to be related to the Aristarchus Plateau boundary fault, which may have controlled the way material was excavated. The hummocky rim unit only occurs on the northern and western rim and may be an overturned flap of premare Aristarchus Plateau bedrock not present near the surface on the southern and eastern rim of the crater. Blocky lobes and smooth flows mainly associated with the hummocky rim unit are interbedded, arguing that the smooth flows are part of the sequence of ejected rocks and are not younger volcanic flows. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.