Structural Architecture and Attenuation of the Ductile Lower Plate of the Ruby Mountain‐East Humboldt Range Metamorphic Core Complex, Northeast Nevada

Abstract Strongly deformed footwall rocks exposed in metamorphic core complexes (MCC) of the North American Cordillera were exhumed via ductile attenuation, mylonitic shearing, and detachment faulting. Whether these structures accommodated diapiric upwelling or regional extension low‐angle normal faulting is debated. The Ruby Mountains‐East Humboldt Range MCC, northeast Nevada, records top‐west normal‐sense exhumation Proterozoic‐Paleozoic stratigraphy older basement. We conducted 1:24,000‐scale mapping southwestern East Range, with integrated structural, geochemical, geochronological analyses to characterize geometry kinematics mylonitized footwall. Bedrock pervasively intruded by Cretaceous, Eocene, Oligocene intrusions, but observations a coherent stratigraphic section show >80% vertical attenuation Neoproterozoic Ordovician rocks. These are penetratively sheared kinematics. shear zone thus experienced combined pure‐ simple‐shear (i.e., general shear) strain. argue that this was syn‐/post‐kinematic respect plutonism because: (a) shearing spatially corresponds preceding intrusions; (b) thermochronology reveals substantial cooling after plutonism; (c) mylonites crosscut undated, likely late Oligocene, leucogranite. propose Eocene mantle‐derived magmatism thermal incubation led middle crust, stretching focused on flanks upwarp. Regional Basin initiated later Miocene. Therefore, development not driven coupled