Talk:Alphonsus (crater)

message: What does "cinder-shaped" mean? Eroica 14:25, 1 October 2005 (UTC)
replies: text: That works. Thanks. — RJH 20:59, 12 December 2005 (UTC)
thread_title: Untitled

message: This is a request for discussion on integrating the following research into the Alphonsus article re; the age of the crater, specifically from a dating of Nectarian ("post-nectarian") to the (late) Pre-Nectarian era.  The reconsideration of the dating of this crater is based upon the following published work:
http://moon.scopesandscapes.com/tlo_back/tlo200606.pdf (2006) "..in accordance with the principle of superposition, the
location of one of these Nectaris basin secondaries (Alphonsus B) on the rim of the crater Alphonsus would necessarily
limit it's age to that era preceding the Nectaris impact event, the Pre-Nectarian."
http://www.lpi.usra.edu/meetings/lpsc2008/pdf/1019.pdf (2008) "Alphonsus B, a teardrop-shaped crater west of Abulfeda D, overlaps ejecta on the east margin of Alphonsus, suggesting that Alphonsus may be Pre-Nectarian, older than previously interpreted [8, 10]."
http://www.beg.utexas.edu/abs/ambrose_lp1_40_pdf1015.pdf (2009) "Chronostratigraphy: Asymmetric secondaries associated with lunar basins are unique morphological features that can be used to constrain estimated ages of overlapped, extrabasinal landforms, such as other cra-ters, scarps, and ejecta from other basins. For example, Alphonsus B, a teardrop-shaped crater west of Abulfeda D, overlaps the outer, east rim of Alphonsus (Fig. 3), suggesting that Alphonsus may be Pre-Nectarian, older than previously interpreted [9, 10]. The long axis of Alphonsus B is oriented radially (azi-muth 002º) toward the center of the Nectaris Basin, consistent with an origin as a secondary crater."
As the validity of the interpretation of the origin of Alphonsus B is critical to re-dating the crater based upon superposition, the continued research results in the area of basin formation secondary craters and other topographical features becomes germane:
http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1061.pdf (2010) ORIGIN, DISTRIBUTION AND CHRONOSTRATIGRAPHY OF ASYMMETRIC SECONDARY CRATERS AND EJECTA COMPLEXES IN THE CRISIUM BASIN
http://www.lpi.usra.edu/meetings/lpsc2011/pdf/1035.pdf (2011) DISTRIBUTION AND CHRONOSTRATIGRAPHY OF EJECTA COMPLEXES IN THE HUMORUM BASIN MAPPED FROM LROC AND LIDAR DATA
http://www.lpi.usra.edu/meetings/lpsc2012/pdf/1048.pdf (2012) EJECTA DISTRIBUTION AND RELATIVE AGES OF THE IMBRIUM, SERENITATIS, AND CRISIUM BASINS
As the author of the 2006 article first referenced, I cannot dismiss the possibility of bias--however, based upon the subsequent research of Ambrose (2008-2012) I feel that there is sufficient confidence in the data to at least call into question the Nectarian era dating of Alphonsus and at best justify a Pre-Nectarian age for this crater.
I look forward to comments.
Mardina Clark 
131.191.114.226 (talk) 20:59, 3 February 2013 (UTC)
thread_title:  Geological era of Alphonsus; updated research 

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