PROTEROZOIC STRUCTURAL RELATIONS WITHIN A THREE-PART SYSTEM OF DIKE INTRUSION, BATHOLITH EMPLACEMENT, AND SHEAR ZONE DEFORMATION AT MID-CRUSTAL DEPTHS NEAR LEADVILLE, COLORADO

Proterozoic rocks exposed in the Sawatch Range of central Colorado record ~1.4 Ga intracontinental deformation that is broadly contemporaneous with the recently identified Picuris Orogeny in northern New Mexico. Updated geologic mapping of the Homestake Reservoir 7.5’ quadrangle near Leadville, Colorado constrains the structural geometry of dike intrusion, batholith emplacement, and shear zone deformation. Mesoproterozoic ultra-potassic dikes intrude Paleoproterozoic gneiss along pre-existing metamorphic foliations. Mesoproterozoic St. Kevin batholith intrudes gneiss and truncates ultra-potassic dikes and includes abundant rafts of host rock, inherited foliations near contacts, and flow foliations. Mesoproterozoic mylonite and pseudotachylite of the Homestake shear zone deform Paleoproterozoic and Mesoproterozoic host rocks. These relations indicate a potentially linked kinematic system of mid-crustal deformation that represents intracontinental effects of the Proterozoic assembly of southern Laurentia.