Reconstructing middle Miocene tectonic boundary conditions Nicholas Herold, Seton, M., Müller, R. D. and You., J. University of Cambridge 11th August, 2008
This talk... Part 1. Reconstructing the oceans Part 2. Reconstructing topography Part 3. Reconstructing middle Miocene palaeogeography – is it worth it? Part 4. Combining palaeogeography with other model boundary conditions
Miocene Climatic Optimum (MCO) Why the Miocene? Miocene Climatic Optimum (MCO) TIME (Ma) Zachos et al. (2001)
Reconstructing the oceans
Age distribution at 15 Ma
Age converted to depth
Depth error based on age
Sediment thickness Global modern sediment thickness: http://www.ngdc.noaa.gov/mgg/sedthick/sedthick.html
Predicted sediment thickness 15 Ma
Large igneous provinces (LIPs) With surrounding seafloor Without surrounding seafloor
Bathymetric reconstruction Age converted depth Age Sediment thickness LIPS
Topography/bathymetry MIOCENE MODERN
Adjustments for climate models Narrow gateways Marginal seas
Mediterranean
Reconstructing Miocene palaeogeography – is it worth it?
General Circulation Model NCAR Community Atmosphere Model and Community Land Model. ~3.75° x 3.75° horizontal resolution, 26 atmospheric layers. cpl lnd ice atm ocn Simulates energy, heat and moisture transfer within and between the atmosphere and land.
Combining palaeogeography with other boundary conditions - Greenhouse gases - Orbital parameters Solar constant River Transport
Mean annual surface temperature
Model-data temperature discrepancies Mean discrepancy: -1.7°C
Model-data precipitation discrepancies Mean discrepancy: -172 mm/year
In summary New Miocene palaeogeography. Preliminary results of a Miocene climate simulation: too cool and arid compared to proxy data. Need to run coupled climate simulations using new palaeogeography in order to better resolve and understand proxy-model discrepancies.
Thanks... Müller, R.D., Sdrolias, M., Gaina, C. and Roest, W.R., 2008. Age, spreading rates and spreading asymmetry of the world's ocean crust. Geochemistry, Geophysics, Geosystems.: Q04006. Müller, R.D., Sdrolias, M., Gaina C., Steinberger B. and C., H., 2008. Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics. Science, 319(5868): 1357-1362.
Kearey and Vine, 1996
Annual zonal mean sea surface temperature
References Stampfli, G.M. and Borel, G.D., 2002. A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons. Earth and Planetary Science Letters, 196(1-2): 17-33.