Tectonic setting of the Taltson magmatic zone at 1.92.0 Ga: a granitoid-based perspective
The Paleoproterozoic Taltson magmatic zone is one of the key tectonic features of western Laurentia. The existing tectonic model for the belt envisions its formation by subduction of oceanic crust beneath a continental margin, followed by direct collision between formerly separate crustal blocks. We tested this model by comparing the large geochemical and isotopic database available for Taltson magmatic zone granitoids with similar databases for Phanerozoic granitoid suites from different tectonic environments. The comparison reveals that the early granitoid suite of the Taltson magmatic zone, which had been ascribed to the subduction phase of orogenesis, lacks the mantle signature apparent in granitoids of Phanerozoic continental-margin arc settings. Instead, both early and late suites appear to have an intracrustal origin, similar to Mesozoic and Cenozoic granitoids of the Cordilleran interior of western North America, which formed in the distant hinterland of a convergent plate margin. In light of thes...