We present paleo-ocean bathymetry reconstructions in a 0.1°x0.1° resolution, using simple geophysical models (Plate Model Equation for oceanic lithosphere), published ages of the ocean floor (Müller et al. 2008), and modern world sediment thickness data (Divins 2003). The motivation is to create realistic paleobathymetry to understand the effect of ocean floor roughness on tides and heat transport in paleoclimate simulations. The values for the parameters in the Plate Model Equation are deduced from Crosby et al. (2006) and are used together with ocean floor age to model Depth to Basement. On top of the Depth to Basement, we added an isostatically adjusted multilayer sediment layer, as indicated from sediment thickness data of the modern oceans and marginal seas (Divins 2003). The Depth to Basement with the appropriate sediment layer together represent a realistic paleobathymetry.
A Sediment Wedge was modeled to complement the reconstructed paleobathymetry by extending it to the coastlines. In this process we added a modeled Continental Shelf, Continental Slope, and Continental Rise to match the extent of the reconstructed paleobathymetry. The Sediment Wedge was prepared by studying the modern ocean where a complete history of seafloor spreading is preserved (north, south and central Atlantic Ocean, Southern Ocean between Australia-Antarctica, and the Pacific Ocean off the west coast of South America). The model takes into account the modern continental shelf-slope structure (as evident from ETOPO1/ETOPO5), tectonic margin type (active vs. passive margin) and age of the latest tectonic activity (USGS & CGMW). Once the complete ocean bathymetry is modeled, we combine it with PALEOMAP (Scotese, 2011) continental reconstructions to produce global paleoworld elevation-bathymetry maps.
Modern time (00 Ma) was assumed as a test case. Using the above-described methodology we reconstructed modern ocean bathymetry, starting with age of the oceanic crust. We then reconstructed paleobathymetry for Cenomanian-Turonian (90 Ma) time. For each case, the final products are: a) a global depth to basement measurement map based on plate model and EarthByte (earthbyte.org) published age of the ocean crust for modern world; b) global oceanic crust bathymetry maps with a multilayer sediment layer based on: i) observed total sediment thickness of the modern oceans and marginal seas, and ii) EarthByte-estimated global sediment data for 00 Ma; c) global oceanic bathymetry maps with reconstructed shelf and slope; and d) global elevation-bathymetry maps (two versions with two types of sediment layers) with continental elevations (PALEOMAP) and ocean bathymetry. Similar maps for other geological times can be produced using this method provided that ocean crustal age is known.
Goswami, A., Hinnov, L., Gnanadesikan, A., and Olson, P. (2013), Global paleobathymetry reconstruction with realistic shelf-slope and sediment wedge, American Geophysical Union Fall Meeting, San Francisco, CA, 5-9 December. Poster PDF