Synchronous vertical and horizontal tectonism during the late stage of Archean cratonization: An important process in gold mineralization?

Abstract

Both vertical and horizontal tectonism played an important role in Archean tectonic evolution. These two processes have independent driving forces and should not be mutually exclusive. In the Superior Province in Canada, there is convincing evidence for synchronous vertical and horizontal tectonism at the late stages of Archean cratonization, and horizontal shearing (a result of horizontal tectonism) is concentrated in synclinal keels (a result of vertical tectonism). The Timiskaming-type sedimentary rocks were deposited in the keels during this process. The synclinal keel-shear zone association provided a link between the upper crust and the lower crust or mantle, and might have served as a conduit for mineralizing fluids and magma that were generated in the crust and/or mantle during the process. Such a process in the late stage of Archean cratonization can readily explain the common association of gold deposits with greenstone belts in synclinal keels, shearzones, late felsic to intermediate intrusions and Timiskaming-type sedimentary rocks.