Dynamothermal metamorphism of the Chiwaukum Schist in the Steven\u27s Pass Area, Cascade Mountains, Washington

The Chiwaukum Schist in the Steven\u27s Pass region of the North Cascade Mountains, Washington is a metamorphic rock suite of pelitic protolith bordering the Mount Steward Batholith. This clay-right parent material experienced contact metamorphism during the intrusion of the Mount Steward batholith, followed by Buchan style, dynamothermal metamorphism. The minerals produced by these early metamorphic events were later overprinted by minerals of Barrovian style, dynamothermal metamorphism. The index minerals of the contact and Buchan facies metamorphism extend into the andalusite zone, while the Barrovian facies is characterized by aluminosilicate polymorph minerals reaching the sillimanite zone. Calculation of mineral abundances and assemblages in thin section allow for the construction of a detailed petrographic analysis of the are