Thermal architecture of the Salmon River suture zone, Idaho, USA: Implications for the structural evolution of a ductile accretionary complex during arc-continent collision

Documenting the tectono-thermal evolution of exhumed ductile portions orogenic systems is critical for interpreting orogen dynamics. Here, we utilize Raman spectroscopy carbonaceous material thermometry to quantify thermal architecture Salmon River suture zone in west-central Idaho, USA, which records Cretaceous collision Wallowa island arc terrane with North America. We integrate this published structural interpretations, geochronology, and pressure-temperature-time histories interpret deformation during arc-continent portion America Cordillera. Mean peak temperatures within four, ~1– 3-km-thick, penetratively deformed thrust sheets western part decrease moving structurally downward from 652 ± 28 °C (Pollock Mountain sheet), 577 30 (Rapid 426 32 (Morrison Ridge 358 18 (Heavens Gate sheet). These are separated by 100–500-m-thick intervals inverted that surround mapped positions faults. as a accretionary complex progressive underplating top-to-the-west translation were derived ca. 144–105 Ma collision-related deformation. Accretion began at ~30–35 km depths completed ~10–20 km. Rocks all levels exhibit distributed fabrics, but gradients faults suggest majority displacement was accommodated 100–500-m-thick, high-strain, thrust-sense shear zones.