Open AccessIssues in planetary chronology
Author(s) -
Barlow Nadine G.,
Schenk Paul,
Bierhaus E. Beau
Publication year - 2007
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/2007eo180005
Subject(s) - chronology , asteroid , astrobiology , planet , solar system , geology , astronomy , physics , paleontology
The ‘Workshop on Surface Ages and Histories: Issues in Planetary Chronology’ brought together researchers from the impact cratering, radiometric analysis, and numerical modeling communities to discuss the current status of chronologic techniques and identify future research directions. Heavily cratered terrains suggest that the inner solar system impact rate was much higher 3.8–4.4 Ga ago (1 Ga = 10 9 years). Impact rates declined after this late heavy bombardment (LHB) period to a level that has been approximately constant for the past 3.8 Ga. A major question is whether the LHB was a gradual decline or a spike near 4.0 Ga. Dynamical modeling of outer planet migrations reveals a mechanism for perturbing material into the inner solar system between 3.8 and 4.0 Ga. Geochronologic evidences from the Moon, Earth, and asteroids also support a cataclysmic LHB.