Abstract

Mantle plumes are often invoked as the ultimate cause of major episodes of continent generation. In this paper we explore the potential of normal plate-tectonic processes to generate intense crustal growth. The central problem is localization of rapid crustal growth into small regions. This can be achieved by transport of terranes parallel to the continental edge in orogenic zones, which we deduce from an analysis of the proportion of present-day continental margins that are dominated by strike-slip motion, together with the proportion of subduction zones showing obliquity >30°. There is a 16% probability of margin-parallel terrane transport on a scale >400 km, and a few margins show transport on a scale >1000 km. The results suggest that concentration of juvenile arc materials into restricted locations can explain both the apparent episodicity and rapid genesis of Precambrian juvenile provinces.

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