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Crater taphonomy and bombardment rates in the PhanerozoicImpact structures can be catalogued according to the age of the rocks in which they are now found ("country rocks"). The observed frequency distribution of craters by age of country rock is shown to be statistically indistinguishable from the predictions of a simple model in which it is assumed that the survival time for craters is the same as that for their target rocks. Other models are considered, but do not match the data. A lower limit of the rate of bombardment through the Phanerozoic, based only on documented craters, is 0.13 +/- 0.09 events/ma/10(8) km2 for craters with diameters > or = 10 km and 0.09 +/- 0.08 events/ma/10(8) km2 for craters with diameters > or = 20 km. The data allow, but do not demand, an increase in meteorite flux over the Phanerozoic but do not allow any significant decrease. We estimate that only about 6% of the existing terrestrial impact structures of diameter greater than 10 km have been discovered to date, and only 16% of those with diameter greater than 20 km.
Document ID
20040090030
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Trefil, J. S.
(George Mason University Fairfax, Va. 22030, United States)
Raup, D. M.
Date Acquired
August 21, 2013
Publication Date
May 1, 1990
Publication Information
Publication: The Journal of geology
Volume: 98
Issue: 3
ISSN: 0022-1376
Subject Category
Geosciences (General)
Report/Patent Number
ISSN: 0022-1376
Funding Number(s)
CONTRACT_GRANT: NAG2-237
CONTRACT_GRANT: W-1527
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Exobiology
NASA Discipline Exobiology
NASA Discipline Number 52-40
Non-NASA Center
Meteoroids
Paleontology
Earth (Planet)
Models, Theoretical
Geology
Support, U.S. Gov't, Non-P.H.S
Support, U.S. Gov't, P.H.S
Support, Non-U.S. Gov't

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