Central Wisconsin was the sight of the emplacement of the Wolf River Batholith during a continent wide period of sporadic anorogenic plutonism. Anorogenic refers to the lack of an active tectonic cause for the heat source that generates large bodies of magmas. The period of 1.5 to 1.4 bya say the emplacement of many of these magma bodies in stable continental crust. These plutons can be seen as a belt that stretches across the continent.

The Wolf River Batholith, emplaced around 1.47 bya, is a complex of five major and four minor petrochemically distinct plutons that follow initial intrusion of two other inital unrelated rock types of anorthosite and monzonite. This differs from other associated anorogenic plutons of the U.S. deposited during this time period, which typically have one intrusion of one rock type.

The oldest and largest pluton if the Wolf River granite, the youngest is the Red River granite and is also the second largest. These two and the other plutons in between have similar characteristics. They all intruded pretty high into the crust, as shallow as 2 to 4 km deep by some estimates. Each successive pluton indicates another generation in differentiation from the original magma. This change can be seen in a rise in the concentration of some rare earth elements quite well. Another interesting tidbit is in the large feldspar crystals in a few of the plutons that changed composition roughly half way through crystallizing, indicating a change in concentrations of certain elements during the process.

The source region is inferred to be at the base of the crust 27 -36 km down where a large blurp of tonalitic to grandoritic magma was trapped and generated melts that rose to toward the surface. There may have been extrusive rocks associated with these magmas, but they have been eroded away since this happened. After the Wolf River, the Great Lakes region fell quiet until the development of the Mid Continental rift system 400 million years later.

Picture of Rapakivi granite near Tigerton. Center is alkali feldspar, the outer ring is Plagioclase