Evidence for a cataclysm ~4.0-3.8 Gy ago

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Evidence for acataclysm ~4.0-3.8Gy ago:The ages of many basins(impact features >200km) cluster in the3.9-3.8 Gy period(Wilhelms, 1987; Ryder,1994)Counter-argument:Basins datations arefooled becausecollected samples aredominated by Imbriumejecta (Haskin, 1998).Only Imbrium is dated.
A LATE HEAVY BOMBARDMENT ?Evidence for a cataclysm ~4.0-3.8 Gy ago:The amount of siderophile elements on the ancienthighlands suggest that the amount of interplanetary massaccumulated by the Moon in the 4.4-3.9 Gy period is aboutthe same of that required to form the basins in the 3.9-3.8Gy period (5 10 21 g), 20 times less than suggested by modelswith a declining bombardment from the time of formationCounter-argument:It critically depends on the assumed composition of theearly impactors. Was it the same as that of the currentmeteorites?
Page 1 and 2: PLANETARY FORMATION5) THE SOLAR SYS
Page 3 and 4: MIGRATION in the SOLAR SYSTEMA gian
Page 5: MIGRATION in the SOLAR SYSTEMIn add
Page 8 and 9: MIGRATION in the SOLAR SYSTEMAs the
Page 10 and 11: MIGRATION in the SOLAR SYSTEMOnce t
Page 12 and 13: A LATE HEAVY BOMBARDMENT ?
Page 14 and 15: A LATE HEAVY BOMBARDMENT ?The Moon'
Page 18 and 19: A LATE HEAVY BOMBARDMENT ?Evidence
Page 20 and 21: A LATE HEAVY BOMBARDMENT ?
Page 22 and 23: A LATE HEAVY BOMBARDMENT ?Some fact
Page 24 and 25: PLANETESIMALS DRIVEN MIGRATION
Page 30 and 31: PLANETESIMALS DRIVEN MIGRATION~1%
Page 36 and 37: PLANETESIMALS DRIVEN MIGRATIONEject
Page 38 and 39: The NICE MODEL
Page 40 and 41: The NICE MODELR. Gomes, H.F. Leviso
Page 42 and 43: The NICE MODELII: A cometaryand ast
Page 44 and 45: JUPITER's TROJANSAt the moment of t
Page 46 and 47: JUPITER's TROJANSSimulations show t
Page 48 and 49: IRREGULAR SATELLITES
Page 50 and 51: IRREGULAR SATELLITES
Page 52 and 53: IRREGULAR SATELLITESUranusNeptuneSa
Page 54 and 55: KUIPER BELT ORIGINDuring the outwar
Page 56 and 57: KUIPER BELT ORIGINDistribution in i
Page 58 and 59: KUIPER BELT ORIGINReproduction of t
Page 60: CONCLUSIONSAlthough the distributio

Evidence for a cataclysm ~4.0-3.8 Gy ago

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