Petrologic Constraints on the Tectonic Evolution of the Llano Uplift

Abstract

Tectonic models for the Proterozoic evolution of the Llano Uplift must account for a two-stage metamorphic history characterized by early dynamothermal metamorphism at high pressures that decreases in intensity from southwest to northeast across the uplift, followed by later, largely static, metamorphism at lower pressures resulting from regionally widespread emplacement of granitic intrusions at relatively shallow levels in the crust.