NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Constraining the Flux of Impactors Postdating Heavy Bombardment Using U-Pb Ages of Impact GlassesSpherules of glass varying in size from a few micrometres to a few millimetres are common in the lunar regolith. While some of these glass beads are products of pyroclastic fire fountains others originate as impact melt ejected from the target that breaks into small droplets and solidifies as spherical particles while raining back to the lunar surface. These glasses preserve information about the chemical composition of the target and often contain sufficient amount of radioactive nuclides such as 40K to enable Ar-40-Ar-39 dating of individual beads. Studies measuring the age of glass beads have been used in attempts to establish variations in the flux of impactors hitting the Moon, particularly during the period that postdates the formation of major impact basins [1,2]. These studies proposed a possibility of spike in the impact flux about 800 Ma [2] and over the last 400 Ma [1]. More recently U-Th-Pb isotopic systems have been also utilized to determine the age of impact glasses from the Apollo 17 regolith [3]. Our aim is to extend the application of the U-Pb system in impact glasses to spherules isolated from Apollo 14 soil 14163 in an attempt to further investigate the applicability of this isotopic system to the chronology of impact glass beads and gain additional information on the impact flux in the inner Solar system.
Document ID
20130008965
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Nemchin, A. A.
(Curtin Univ. of Technology Perth, Australia)
Norman, M. L.
(Australian National Univ. Canberra, Australia)
Ziegler, R. A.
(NASA Johnson Space Center Houston, TX, United States)
Grange, M. L.
(Curtin Univ. of Technology Perth, Australia)
Date Acquired
August 27, 2013
Publication Date
March 18, 2013
Subject Category
Lunar And Planetary Science And Exploration
Report/Patent Number
JSC-CN-27960
Meeting Information
Meeting: Lunar and Planetary Science Conference
Location: The Woodlands, TX
Country: United States
Start Date: March 18, 2013
End Date: March 22, 2013
Distribution Limits
Public
Copyright
Public Use Permitted.
No Preview Available