Pangea's complex breakup: A new rapidly changing stress field model

Abstract

Over the years numerous proposals have been presented describing the relationship between the Central Atlantic Magmatic Province (CAMP) and the break-up of Pangea. Recent proposals have focused on refuting the original proposal of a mantle plume origin for the large igneous province and attendant dikes, and instead propose an upper mantle or passive cause for the break-up and CAMP. In this paper we examine the fundamental assumption that the multiple dike orientations associated with the break-up are geographically or temporally delimited. New mapping and compilations of older local maps demonstrate that multiple dike orientations ranging from NW- to NE-trending were intruded throughout the western Carolinas and are not geographically limited. Further, new plagioclase 40Ar / 39Ar dates indicate that all three orientations observed were emplaced within a 2 Ma period (c.a. 199–197 Ma). Based on this information we propose that a rapidly rotating stress field must be responsible for the emplacement of multiple dike orientations in the Carolinas and the break-up of Pangea and go on to propose several new tectonic models to account for this rotating stress field.