Metacraton: Nature, genesis and behavior
Earth and related Environmental sciences
Geodynamics and mineral resources
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In this paper, we show with examples that cratons involved in intercontinental collisions in a lower plate position are often affected by orogenic events, leading to the transformation of their margins. In some cases, craton interiors can also be shaped by intense collisional processes, leading to the generation of intracratonic orogenic belts. We propose to call these events metacratonization and the resulting lithospheric tract metacraton . Metacratons can appear similar to typical orogenic belts (i.e. active margin transformed by collisional processes) but are actually sharply different. Their main distinctive characteristics (not all are present in each metacraton) are: (1) absence of pre-collisional events; (2) absence of lithospheric thickening, high-pressure metamorphism being generated by subduction, leading to high gradient in strain and metamorphic intensity; (3) preservation of allochthonous pre-collisional oceanic terranes; (4) abundant postcollisional magmatism associated with shear zones but not with lithospheric thickening; (5) presence of high-temperature low-pressure metamorphism associated with post-collisional magmatism; (6) intracontinental orogenic belts unrelated to subduction and oceanic basin closures. Reactivation of the rigid but fractured metacratonic lithosphere will cause doming, asthenospheric volcanism emplacement, and mineralizations due to repetitive mineral enrichments. This paper provides several geological cases exemplifying these different metacratonic features in Scandinavia, Sahara, Central Africa and elsewhere. A special focus is given to the Saharan Metacraton because it is where the term metacraton originated and it is a vastly expanded tract of continental crust (5,000,000 km2). Metacratonization is a common process in the Earth's history. Considering the metacraton concept in geological studies is crucial for understanding the behavior of cratons and their partial destruction.
CitationLiégeois, J.P.; Abdelsalam, M.; Ennih, N.; Ouabadi, A. (2013). Metacraton: Nature, genesis and behavior. , Gondawana Research, Vol. 23, 220-237, Elsevier, DOI: 10.1016/j.gr.2012.02.016.