DERCAP Workshop 2009 Building a Virtual Geological Observatory Dietmar Müller School of Geosciences, University of Sydney
Virtual Observatories... have revolutionized astronomy by giving people anywhere in the world access to a vast array of sky observations and tools
Planetary observation a remarkable success We now know more about the surface topography of Mars than of Earth! Why? There are no oceans on Mars...
Earth s topography Australia
Earth observation A multitude of observation methods More than satellites and space probes...
... and plate tectonics!
Earth observation Plate tectonics makes Earth special
Changing face of geoscience Global climate change and shrinking resources have heightened our sense of dependence on the earth as a dynamic and complex system Earth Science is data rich and information poor, a balance worsening year by year due to the flood of remotely sensed data Data sets orders of magnitude larger and more complex The Earth as we know it today is the product of hundreds of millions of years of plate tectonic motions, mountain building, erosion, climate and sea-level change We need to amalgamate data and connect them to analysis and process modelling tools Virtual Observatory a potential unifier
A Virtual Observatory is A set of international standards to share complex data A set of tools to visualize and analyze complex data A set of tools to connect observations to process models, especially high-performance computing Google Earth a good example, but standards to share complex data (KML) are poorly conceived
Observatory prototype: GPlates Funded via AuScope National Collaborative Research Infrastructure (NCRIS) and ARC Laureate Fellowship - both 5 year programs International collaborative nodes (Caltech, Univ. Oslo) GPlates: Integrate plate tectonic and geodynamic models with geological and geophysical data in a Plate Tectonic GIS Use information model standard: Geographic Markup Language (GML)
Science applications Earth s paleogeography and sea level change A global sea level rise of 1 metre, driven by melting inland ice sheets, is considered to have disastrous effects on up to 60 million people worldwide However, much larger fluctuations have existed in the ancient past, when neither humans nor ice caps existed. What drove these changes?
Long-term sea level change driven by changing ocean basin volume
Palaeogeography 150-50 my ago
Large-scale surface topography driven by mantle convection Burgess et al., 1997 Steinberger 2007
Link plate kinematics with the mantle to develop dynamic Earth models 4-D equivalent to plate tectonics Test alternative plate kinematic models Model plate boundary dynamics Model vertical motions due to mantle convection Model global and regional sea level change Model palaeoclimate Compute mantle heat flow Need to assimilate geological data into models
Mantle convection models (CitcomS) assimilate many data sets use Geoframework (Michael Aivasis) Palaeoage grids, plate velocities Back-arc Conditions Surface temperatures Mantle temperature field 16
Reconstructed ocean floor and plate velocities
Applications of the method: North and South America, Australia Western Interior Seaway: 80 Ma Well documented flooding and dynamic subsidence in Western Interior Seaway in the Cretaceous Period Ron Blakey, http://jan.ucc.nau.edu/~rcb7/nam.html
Dynamic topography in a plate frame as NA Sweeps west Over the Farallon Slab in inverse model Liu et al. (2008)
This animation shows a W-E cross section of a geodynamic model. The color coding is mantle temperature, the blue line is the E-W velocity, and pink is the surface dynamic topography. The triangle is near Denver, Colorado. Liu 11 et Jan al., 2005 Science, 2008
Australian example: plate motions and mantle convection-driven dynamic surface topography
Australian topography from 70 m.y. ago
South America Roddaz et al. 2005
Amazon River reversal Mid-Miocene reversal of flow Attributed to Andes uplift Long-wavelength subsidence of central and eastern basins Hoorn et al., 1995
South America geodynamics
Palaeoclimate over last 60 million years hothouse to icehouse
Palaeoclimate over last 60 million years hothouse to icehouse
Present Earth topography
Miocene topography 15 my ago
Thermohaline circulation thresholds
Community Climate System Model 3 Can prescribe Miocene orbital parameters, greenhouse gases, topography, vegetation, sea surface temperature 6
Ocean temperature Modern Miocene 1,000m 2,000m C 3,000m 4,000m Annual mean water temperature as a function of latitude and depth. The Arctic is significantly warmer in the Miocene. While cool water flows out through the Fram Strait at the surface (the only gateway into the Arctic), warmer water enters at depth.
Miocene deep water formation 2,000 m Age of deep water 3,000 m 4,000 m Years All deep water formation occuring in the Weddell Sea, as opposed to the North Atlantic at present
VIRGO Virtual Geological Observatory Future outlook Capture results of observation and computation into a 4- dimensional environment (space and geological time) and test alternative Earth evolution models including climate, sea level Integrate data/models/tools in an interoperable fashion (standard data format GML) data mining in 4D! International collaboration for development (Usyd, Caltech, NGU, Univ. Oslo) Prototype: GPlates software (www.gplates.org) Growing user group including industry Many challenges...