Projects

Core Formation in the Lab
Sensitivity of a Coupled Earth System Model to Isopycnal Stirring
Climate interactions forced by continent assembly and breakup
The Young Inner Core
F-layer formation at the inner core boundary
How increasing mixing warms the polar regions
Modeling the Geodynamo
Global Paleobathymetry and Ocean Sediment Reconstruction
Magnetic Reversals and the Earth's Core
Geomagnetic Superchron Cycles Driven by Mantle Convection
Mantle convection, plates, and the Earth system
Geodynamic Carbon Cycling


Global Paleobathymetry & Ocean Sediment Reconstruction with Realistic Shelf-Slope and Sediment Wedge


Crust Oceans

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

Modern Bathymetry (click for full resolution)


Figure 1: Modern ocean bathymetry reconstructed using three parameterizations: (1) a plate model for basement depth versus crustal age that uses published data on the global ocean floor age distribution; (2) a model for deep ocean sediment thickness versus crustal age derived from published global sediment thickness data; (3) a model for sediment wedges on continental shelfs, slopes, and rises derived from published global sediment thickness data near continental margins. This reconstructed bathymetry does not take into account ocean plateaus, islands, or seamounts.

90 Ma Reconstruction (click for full resolution)


Figure 2: Ocean bathymetry reconstructed for 90 million years ago (Cenomanian-Turonian age boundary) using the sediment parameterizations (2) and (3) from Figure 1, plus published data on the locations of the continents and the global ocean floor age distribution from that time.



References

Amante et al., 2009, ETOPO1 1 Arc-Minute Global Relief Model: Procedures, Data Sources and
       Analysis; NOAA Tech. Memo. NESDIS NGDC-24.

Crosby et al., 2006, The relationship between depth, age and gravity in the oceans;
       Geophy. J. Int., 166.2, 553-573.

Divins, D.L., 2003, Total Sediment Thickness of the World's Oceans & Marginal Seas;
       NOAA, Boulder, CO.

Geological map of the world (1:25,000,000 scale), 3rd edition (2010), Paris, France.

Geologic Province and Thermo-Tectonic Age Maps from USGS website
       earthquake.usgs.gov/research/structure/crust/maps.php

Müller et al., 2008, Age spreading rates and spreading asymmetry of the world's ocean crust; GGG 9.

Müller, R.D., Sdrolias, M., Gaina, C., Steinberger, B. and Heine, C., 2008a,
        Palaeo-age, depth-to-basement and bathymetry grids of the world's ocean basins from 140-1 Ma,
        Science, 319, 1357-1362.

Scotese, C.R., 1991. Jurassic and Cretaceous plate tectonic reconstructions; PPP, 87, 493–501

Scotese, C.R., 2011. The PALEOMAP Project PaleoAtlas for ArcGIS, Volume 1 & 2, PALEOMAP Project.

Turcotte, D.L., and Schubert, G., 2002, Geodynamics, 2nd Edition, Cambridge University Press, Cambridge, 456 p.

Whittaker, J., Goncharov, A., Williams, S., Müller, R. D., Leitchenkov, G., 2013.
        Global sediment thickness dataset updated for the Australian-Antarctic Southern Ocean,
        Geochemistry, Geophysics, Geosystems. DOI: 10.1002/ggge.20181