Geological Analysis of the Northern Margin of the Boulder Batholith : an EdMap Project.

Abstract

Southwest Montana experienced large-scale magmatism and regional contraction during the Late Cretaceous. Understanding the genetic linkages between these geologic processes is important for understanding the causes of mountain-building in the Cordillera. The relationship between the plutonic rocks of the Boulder batholith, the coeval volcanic rocks of the Elkhorn Mountain volcanics, and the folding and thrusting associated with foreland contraction is the subject of ongoing debate. Our analysis of the field relationships between the Boulder magmatic system and the folded Paleozoic rocks constrain the sequence of events that shaped the technomagmatic evolution of the Helena salient.