Paper No. 5
Presentation Time: 2:50 PM
TOWARD FULFILLING WEGENER'S AND WILSON'S VISIONS: CONTINUOUS PRECAMBRIAN GLOBAL CRATON KINEMATICS
EVANS, David A.D., Department of Geology and Geophysics, Yale University, New Haven, CT 06520, EGLINGTON, Bruce, Saskatchewan Isotope Laboratory, University of Saskatchewan, 114 Science Place, Saskatoon, SK K1Y 3L5, Canada and PEHRSSON, Sally, Geological Survey of Canada, 601 Booth Street, Ottawa, ON K1A 0E8, Canada, david.evans@yale.edu
Seafloor magnetic isochrons provide the most powerful means of reconstructing global plate kinematics, but they are limited to the past 200 million years, less than 5% of Earth history. Global craton reconstruction, using paleomagnetism and tectonic-stratigraphic synthesis, is tractable as far back as the rock record permits: sub-greenschist rocks amenable to paleomagnetic study can be found on many terranes throughout the Proterozoic interval. Exciting new developments in paleomagnetic methods (more careful application of field stability tests on the ages of magnetization), geochronology (particularly U-Pb on zircon, baddeleyite, and other U-bearing minerals), and software (notably the GPlates cross-platform freeware) have led to a rapid advancement in pre-Pangea craton reconstructions within the past few years. Speculations on supercontinent assembly and dispersal, known as the Wilson cycle, rely crucially on these kinematic constraints.
We present the first continuous global craton animation through much of Proterozoic time, between 2.0 and 1.2 Ga. We subdivide the world’s continental geology into more than 500 terrane polygons, which are treated as internally rigid. The terrane boundaries have been chosen according to tectonic/stratigraphic information, GIS-rendered geological maps, and geophysical data. Geological features such as orogens, large igneous provinces, and mineral deposits are linked directly to the kinematic framework via the StratDB database with ~100,000 geochronology records. The animation model is compatible with PaleoGIS and GPlates software, incorporating constraints from paleomagnetism as well as tectonics and stratigraphy. Our model proposes a geometrically accurate Nuna supercontinent configuration, as well as a history of its amalgamation and dispersal. The model is likely to be revised significantly as new data arise, but it represents a step change in the visualization and analysis of craton kinematics in deep time.
