FIELD MAPPING AND GEOLOGICAL HISTORY IN IGNEOUS ROCKS OF THE CENTRAL MINNESOTA BATHOLITH, WAITE PARK, MINNESOTA

Field work was conducted on a series of outcrops in the Early Proterozoic Central Minnesotan Batholith at the Radio Tower locality in Waite Park, MN. A range of igneous lithologies, some of which are mixed, as well as a series of variously-oriented fractures were mapped. From this, the relative age of each lithology and the inferred history of events has been determined. A series of outcrop maps partnered with collected samples show align with pre-existing trends in Minnesota. A total of four lithologies and three fracturing events have been identified. The oldest unit is a granodiorite, which is succeeded by a quartz alkali feldspar syenite. The first fracturing event on a north-south trend. Subsequently, is a pair of aplite dikes and a second east-west fracture set. Lastly, a basalt dike on-trend with those seen in the Central Minnesotan Batholith and a final north-south fracturing event. Glacial striations and polishing are absent from outcrops at the Radio Tower locality, compared to exposures at Quarry Park less than half a mile away. A complex history of deep chemical weathering and variable removal by ice probably accounts for this.