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Impact melting early in lunar historyThe total amount of impact melt produced during early lunar history is examined in light of theoretically and experimentally determined relations between crater diameter (D) and impact melt volume. The time dependence of the melt production is given by the time dependent impact rate as derived from cratering statistics for two different crater-size classes. Results show that small scale cratering (D less than or equal to 30 km) leads to melt volumes which fit selected observations specifying the amount of impact melt contained in the lunar regolith and in craters with diameters less than 10 km. Larger craters (D greater than 30 km) are capable of forming the abundant impact melt breccias found on the lunar surface. The group of large craters (D greater than 30 km) produces nearly 10 times as much impact melt as all the smaller craters, and thus, the large impacts dominate the modification of the lunar surface. A contradiction between the distribution of radiometric rock ages and a model of exponentially decreasing cratering rate going back to 4.5 b.y. is reflected in uncertainty in the distribution of impact melt as a function of time on the moon.
Document ID
19800039547
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Lange, M. A.
(California Institute of Technology, Pasadena, Calif.; Kiel, Neue Universitaet Kiel, Germany)
Ahrens, T. J.
(California Institute of Technology Pasadena, Calif., United States)
Date Acquired
August 10, 2013
Publication Date
January 1, 1979
Subject Category
Lunar And Planetary Exploration
Meeting Information
Meeting: Lunar and Planetary Science Conference
Location: Houston, TX
Start Date: March 19, 1979
End Date: March 23, 1979
Accession Number
80A23717
Funding Number(s)
CONTRACT_GRANT: NSG-7129
Distribution Limits
Public
Copyright
Other

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