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Transportation of detrital materials on the lunar surface: evidence from Apollo 15
Author(s) -
LINDSAY JOHN F.
Publication year - 1974
Publication title -
sedimentology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.494
H-Index - 108
eISSN - 1365-3091
pISSN - 0037-0746
DOI - 10.1111/j.1365-3091.1974.tb02062.x
Subject(s) - ejecta , geology , meteorite , impact crater , geology of the moon , lunar mare , debris , sorting , pebble , fluidization , regolith , petrology , geomorphology , astrobiology , geochemistry , basalt , oceanography , physics , fluidized bed , quantum mechanics , supernova , programming language , waste management , engineering , computer science
The thickness frequency distribution of stratigraphic layers intersected by the Apollo 15 deep core suggests that the majority of impact events reworking the lunar soil are small and produce ejecta blankets with an average thickness of less than 1·D5 cm. The energy frequency distribution of the meteorites producing the layers may be bimodal. The impacting meteorites produce both normal and reverse graded beds which appear to be the end products of two depositional mechanisms. First, the normally graded beds appear to be produced in base surges as escaping gases fluidize the flowing debris and larger particles move downwards in response to Stokes Law. Second, if the gas loss from the base surge is excessive the fluidization may cease and inertial grain flow dominates. In this situation the beds are reverse graded as larger particles move under dispersive pressure to the region of minimum shear stress at the upper boundary of the base surge. The same processes also produce measurable shape sorting of the particles in the beds.