Intermontane terranes
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The Intermontane terranes were a group of volcanic island arcs that formed in the Panthalassa Ocean during the Triassic period. These terranes developed above subduction zones and were later accreted to the western margin of North America during the Jurassic. Offshore, a separate assemblage known as the Insular belt evolved independently. The ocean basin between the Intermontane terranes and the North American craton is known as the Slide Mountain Ocean, remnants of which are preserved in the Slide Mountain terrane. Some tectonic models suggest multiple, possibly parallel subduction systems, analogous in part to the modern Philippine Mobile Belt.[1]
Collision of the Intermontane Islands
[edit]During the Early Jurassic, convergence between the Intermontane terranes and the western margin of North America led to subduction of the intervening Slide Mountain Ocean. This subduction generated a continental-margin volcanic arc, producing widespread granitoid intrusions within the continental interior. By the Early to Middle Jurassic, closure of the ocean basin culminated in the collision and accretion of the Intermontane terranes to North America.[1]
Because these terranes consisted of relatively buoyant island-arc crust, they resisted subduction, leading instead to accretion at the continental margin. This collision modified or terminated earlier arc magmatism and was followed by a reorganization of plate boundaries, with subduction shifting westward to offshore terranes of the Insular belt.[2]
References
[edit]- 1 2 Colpron, Maurice; Sack, Peter J.; Crowley, James L.; Beranek, Luke P.; Allan, Michael M. (2022). "Late Triassic to Jurassic Magmatic and Tectonic Evolution of the Intermontane Terranes in Yukon, Northern Canadian Cordillera: Transition From Arc to Syn-Collisional Magmatism and Post-Collisional Lithospheric Delamination". Tectonics. 41. American Geophysical Union. doi:10.1029/2021TC007060.
- ↑ Colpron, Maurice; McClelland, William C.; Piercey, Stephen J.; Kroeger, Emma D. L.; Crowley, James L.; Gehrels, George E. (2025). "Revisiting the "Klondike Orogeny": Permian to Jurassic Development of the Yukon-Tanana Terrane, Northern Canadian Cordillera". Tectonics. 44 (6). John Wiley & Sons. doi:10.1029/2024TC008748. ISSN 0278-7407.
