Skip to Main Content
Skip Nav Destination

The Morton Gneiss in the Minnesota River Valley, southwestern Minnesota, consists of an older metamorphic complex of tonalitic gneisses and amphibolites (the paleosome) and younger granitic gneisses (the neosome). Discordant U-Pb ages on zircon from the tonalitic gneisses give a minimum age of 3,300 m.y. with indications of an older age. An age of approximately 3,500 m.y. is indicated by Rb-Sr data for the tonalitic and related granodioritic gneisses; however, subsequent events have disturbed the Rb-Sr as well as the U-Pb systems in the Archean rocks. In addition to the early folding that formed the metamorphic complex, these subsequent events...

You do not currently have access to this chapter.

Figures & Tables




Citing Books via

Related Articles
Related Book Content
Close Modal

or Create an Account

Close Modal
Close Modal