Milankovitch Cycle Evolution and Uncertainty. Dave Waltham. Outline. C roll-Milankovitch cycles Application to c yclostratigraphy Earth-Moon system evolution The time-varying drag problem Time-evolution of CM cycles and their (big) uncertainties Beware!. Croll-Milankovitch Cycles. - PowerPoint PPT Presentation
PowerPoint Presentation
Milankovitch Cycle Evolution and UncertaintyDave
WalthamOutlineCroll-Milankovitch cyclesApplication to
cyclostratigraphyEarth-Moon system evolutionThe time-varying drag
problemTime-evolution of CM cycles and their (big)
uncertaintiesBeware!
Croll-Milankovitch Cycles
Cyclostratigraphy
Wu et al, 2013. Time-calibrated Milankovitch cycles for the late
Permian, Nature CommunicationsEarth-Moon System EvolutionEarth-Moon
System Evolution
da/dt = f a-5.5Earth-Moon System Evolution
Earth-Moon System Evolution
Time Varying Drag
f = 2.010.03 x 1038 m6.5 s-1 Time-Varying Drag
Don Dixonf = 6.850.08 x 1037 m6.5 s-1 = (0.3440.004)
f0Time-Varying Drag
OR11Time-Varying DragStochastic VariationLog-normal variationf =
exp( m + s 2/2 )Secular IncreaseResonance in oceans is predicted to
peak when day length ~ 27 hours (Webb, 1982)
Time-Varying DragStochastic variationMonte-Carlo
SimulationSecular increaseExponential approximation
Time-Varying DragGeological ConstraintsTidal RhythmitesOnly
really good ones are from Elatina/Reynella (Williams, 1989, 2000;
Deubner, 1990)62020 Maf = (0.510.02) f0
Time-Varying Drag
Time-Varying Obliquity
Time-Varying ObliquityWeb-based Tool
Beware!
