Archean cratons, fragments of ancestral supercratons: Insights from paleo-continental reconstructions

Abstract: Archean cratons and their crustal/lithospheric evolution are commonly studied and discussed as isolated entities. They are not. Instead they are remaining fragments of larger, ancestral, Archean supercratons the same way that Africa is a fragment of Gondwana or Pangea. This scale perspective is important as the processes that formed Archean cratons, or rather their ancestral supercraton, are typically larger than any remaining craton or fragment. Archean supercratons—continents in a sense— have since rifted apart and been dispersed by several plate tectonic cycles, such that the solution to a major tectonic question on one craton may be found on a formerly adjacent but now distant crustal fragments. Like for so many problems and processes in the earth sciences, the study of Archean cratons should be done on a global scale. This is daunting but very doable. There are ~35 Archean cratons remaining and perhaps another ~15 variably deformed slivers. Thus, the Archean rock record is a puzzle in 50 pieces, and a less well defined number of pieces that got lost over time, perhaps to the vacuum cleaner of subduction erosion. Long-term preservation was almost certainly biased to thick stable lithosphere, such that the remaining fragments may not give a fully representative picture. In this talk I will present an overview of how far we have come with reconstructing this Archean puzzle, and some of the exciting new insights that follow from that.

About Wouter: Wouter Bleeker is a scientist with the Geological Survey of Canada in Ottawa. He obtained degrees in geology and ore petrology from the Free University of Amsterdam, the Netherlands. In collaboration with industry, his M.Sc. degree involved unravelling the structure and stratigraphy of an ore-bearing horizon in the Bergslagen mining district of central Sweden, where his work contributed to the discovery and economic mineral extraction of a massive sulphide deposit. He then spent two years in southern Africa as a lecturer at the University of Botswana. He obtained his Ph.D. from the University of New Brunswick with a dissertation on the structure and stratigraphy of the Thompson Nickel Belt and its nickel sulphide deposits. Following his Ph.D., he joined Falconbridge Exploration as their in-house structural specialist, before coming to the GSC in 1994. With the GSC, and a through a number of international collaborations, he has worked on numerous Precambrian terrains and cratons around the world, notably the Slave, Superior, Karelia, Kaapvaal and Yilgarn cratons.