Gravity domains and assembly of the North American continent by collisional tectonics

Abstract

Trends of geophysical anomalies have made important contributions to local and regional structural studies within the North American continent1,2, particularly in examining the Precambrian basement underlying the relatively undeformed Phanerozoic sediments that cover ∼45% of North America3–5. Here we present a gravity trend map of North America, based on a horizontal Bouguer gravity gradient map6 produced from gravity data for Canada and the conterminous United States, and use it to define a continental mosaic of gravity trend domains akin to structural domains. Contrasting trend characteristics at gravity domain boundaries support the concept of the outward growth of the continent primarily by accretionary (collisional) tectonics. Gravity patterns, however, indicate a different style of tectonics dominated in the development of now-buried Proterozoic orogenic belts in the south`central United States, supporting a view that these belts formed along the leading edge of a southward-migrating Proterozoic continental margin7.