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- volume 15 (2012)
- number 3
- From Wegener until now: the development of our understanding of Earth’s Phanerozoic evolution (André Dumont medallist lecture 2012)
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From Wegener until now: the development of our understanding of Earth’s Phanerozoic evolution (André Dumont medallist lecture 2012)
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Abstract
Since Wegener (1912) proposed that all of the Earth’s land areas once formed a single supercontinent that later moved apart (continental drift), our description of the movement and deformation of the Earth's outer layer have evolved into seafloor spreading (1962) and then to plate tectonics by the mid-late 1960s. Results from palaeomagnetic studies in the 1950s were one of the principal reasons why the plate tectonic theory was accepted in the 1960s, and they have proved crucial in the objective positioning of older rocks, some dating from as far back as the Archaean. If we compare Wegener's supercontinent (Pangea) with modern reconstructions, which are based on a much larger database and more disciplines, there are many similarities, but the most striking difference is that we are now able to position Pangea and other continents at their original latitude and longitude. Our knowledge of Pre-Pangean palaeogeography has improved considerably over the past few decades, and has spurred an intensive search for older supercontinents. Many scientists did not accept continental drift for the lack of a mechanism. Ironically, there is still no generally accepted mechanism that explains plate tectonics in the framework of mantle convection, nor is it clear why Earth is the only terrestrial planet with plate tectonics. The presence of water might be a prime factor, but the challenge now is to develop an Earth model that can link plate tectonics with mantle convection through time, and which allows for elements such as deeply subducted slabs and stable thermo-chemical piles at the core-mantle boundary, with plumes rising from their edges.
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A propos de : Trond H. TORSVIK
Center for Physics of Geological Processes (PGP), University of Oslo, 0316 Oslo, Norway.
A propos de : L. Robin M. COCKS
Department of Palaeontology, The Natural History Museum, London SW7 5BD, U.K.