The Wolf River Batholith (1500 Ma old)
The Wolf River Batholith consists of a large anorogenic granitic intrusion that extends from near Wausau to Shawano and in the subsurface at least to Oshkosh. It extends from Waupaca on the south to Lakewood on the north. There are also several satellite intrusions, notably the Wausau Syenite.
Within the intrusion is the Tigerton Anorthosite. Although this rock looks like a single unit on the map, it is actually an area of scattered inclusions within the granitic rocks. No two maps show it the same because of its ill-defined extent. In a number of other areas, notably southeast Wyoming, large granitic and anorthosite intrusions are associated. The main body of the Tigerton anorthosite is probably beneath the Wolf River Batholith, and the surface inclusions were likely carried up by the granitic magma. The anorthosite lies over the deepest part of a gravity low that probably marks the main conduit for the intrusion of the batholith.
Note also, beginning with this map, that the rift complex in northwestern Wisconsin has been peeled away. The underlying crust is probably an Archean greenstone-granite terrane similar to adjacent Archean rocks in Minnesota and Michigan. There are no data for these rocks in Wisconsin and the contacts shown are solely to simulate the map appearance of a typical greenstone-granite terrane.
Created 11 Sep 1997, Last Update 02 April 2013
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