Comparing Paleoproterozoic Felsic Volcanic Centers Across Wisconsin : Implications for Tectonic History and Sulfide Mineralization

Abstract

The rocks containing the Crandon deposit are part of the Pembine-Wausau Terrain and formed ~1.85 billion years ago. These formed in a bark-arc setting as part of the Penokean Orogeny. Arc-derived sediments eventually covered the ocean vent systems. The accretion of the Marshfield Terrain resulted in low grade metamorphism and small intrusions to the Crandon deposit. This is true for the rocks from the Eisenbery suite as well. The Lobo deposit is a part of the Wisconsin Magmatic Terranes composed of plutonic, volcanic, and sedimentary rocks that were accreted during the collision of the Pembine-Wausau terrane and Superior craton during the Paleoproterozoic Penokean orogeny. The host rocks of the Lobo deposit are primarily sericite-altered lapilli tuff. The wolf river deposit is like the lobo deposit in that the Wolf River is a composite deposit, and the lobo deposit is one of its clusters. The Flambeau Cu-Zn Deposit in Northwestern Wisconsin is only 4 miles from the Eisenbery Deposit but is geochemically distinct indicating a distinct and different environment that it formed in.