Sonju Lake intrusion, Beaver Bay Complex, Beaver Bay, Lake Co., Minnesota, USA

Sheet-like intrusion with a thickness of about 1200m, including a basal contact zone of melatroctolite, followed by dunite, troctolite, gabbro, oxide-rich gabbro, apatite olivine diorite, and an upper monzodiorite. A Pt-Pd-rich precious metal zone occurs within the oxide-rich gabbro.

Ref.:
- Chusi Li, Ripley, E.M., Oberthür, T., Miller, Jr., J.D., and Joslin, G.D. (2008): Textural, mineralogical and stable isotope studies of hydrothermal alteration in the main sulfide zone of the Great Dyke, Zimbabwe and the precious metals zone of the Sonju Lake Intrusion, Minnesota, USA. Mineralium Deposita 43, 97-110.