Petrography of the Suflide Ore Zones in the Lynne Zn-Cu-Pb Deposit, Oneida Co., Wisconsin

Abstract

This study examines the sulfide mineralization of three of the ore zones within in the Lynne Zn-Cu-Pb deposit to determine how the mineralizing hydrothermal system formed and evolved over time. These sulfide mineral ores were formed in a volcanic massive sulfide (VMS) that are formed through hydrothermal vents in submarine environments. The Lynne deposit is in northern Wisconsin near Rhinelander, and it is part of the 1.8-1.9-billion-year-old Pembine-Wausau terrane. The Lynne deposit was discovered by Noranda Exploration in 1990 and consists of mainly zinc, copper, and lead sulfides. Drill core obtained during mineral exploration efforts in 1990-91 were re-logged and, their ore zones were described in detail. Samples collected from these cores were cut into thin sections for reflected-light petrography. These thin sections were also analyzed on a scanning electron microscope to obtain mineral chemistry data and identify sub-microscopic minerals that are more sensitive to fluid conditions than traditional Zn-Cu-Pb sulfides. This project illustrates the mineralogical characteristics that makes the Lynne deposit unique when compared to other VMS deposits in Wisconsin.