How Earth works 100 years after Wegener's continental drift theory and IGCP 648

Abstract:

It took half a century for Wegener's continental drift theory to be accepted as a fundamental element of the plate tectonic theory. Another half a century on, we are still unsure of the driving mechanism for plate tectonics: is it dominated by thermal convection, gravitational forces, or by a combination of mechanisms? Nonetheless, breakthroughs in the past decades put us in a position to make a major stride in answering this question. These include: (1) widely accepted cyclic occurrences of supercontinent assembly and break-up (whereas random occurrence of supercontinents was an equal possibility in the 1990s); (2) the discovery of two equatorial and antipodal large low seismic velocity provinces (LLSVPs) that dominate the lower mantle and appear to have been the base for almost all mantle plumes since at the Mesozoic, and of subduction of oceanic slabs all the way to the core-mantle boundary, which together suggesting whole-mantle convection; (3) the

recognition of true polar wander (TPW) as an important process in Earth

history, likely reflecting Earth's major internal mass redistribution

events; and (4) rapidly enhancing computer modelling power enabling us to simulate all aspect of Earth's dynamic inner working. Many new yet often controversial ideas have been proposed, such a possible coupling in time (with an offset) and space between supercontinent cycle and superplume (LLSVP) events which oppose to the idea of static and long-lived LLSVPs, and the orthoversion v.s. introversion or extroversion models for supercontinent transition. To fully utilise these advances as well as the rapidly expanding global geoscience databases to address the question of how Earth works, an UNESCO-IUGS sponsored IGCP project No. 648 was formed to coordinate a global cross-disciplinary effort. We aim to achieve a better understanding of the supercontinent cycle, and examine the relationship between supercontinent cycle and global plume events. We will establish a series of global geological and geophysical databases to enable the geoscience community to make data-rich visual paleogeographic reconstructions using software like GPlates. In addition, the project will bring the geotectonic and the geodynamic modelling communities together to test global geodynamic models into the geological deep time.