North-Central - 52nd Annual Meeting

Paper No. 14-24
Presentation Time: 8:00 AM-5:30 PM

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


PANGERL, Mackenzie, AHS Department, Geology, Saint Cloud State University, 720 Fourth Avenue South, Saint Cloud, MN 56301

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.