Comparison of Hydrothermal Alteration Zones Associated with the Flambeau and Eisenbrey Massive Sulfide Deposits, Rusk County, WI

Abstract

The Flambeau and Eisenbrey Cu-Zn-Pb-Au-Ag deposits are hosted within the Pembine-Wausau terrane of the Penokean Orogen, which is a 1.8-1.9 billion year old volcanic arc sequence consisting of volcanic and sedimentary rocks, and associated mafic and felsic plutonic rocks. The Pembine-Wausau terrane hosts many other similar polymetallic deposits but their geologic and economic significance has only recently been examined in a modern context by UW-Eau Claire student-faculty collaborative research. Following the discovery of the Flambeau deposit, mapping efforts elsewhere in the Penokean Orogen resulted in the discovery of an outcropping iron formation and subsequent drilling outlined the Eisenbrey ore body on the banks of the Thornapple River only 4 miles away from the proposed Flambeau mine site. However, the geologic and hydrothermal characteristics of these adjacent ore bodies have never been compared until this study.