Implications for evaporite tectonism in the Carbondale and Eagle collapse centers of west-central Colorado, based on reprocessed seismic reflection data

Reprocessing of approximately 64 km of seismic reflection data along five seismic lines has led to new interpretations of evaporite tectonism associated with the Pennsylvanian Eagle Valley Evaporite of the central Colorado trough. Evidence of the oldest evaporite tectonism in the region, imaged by the seismic data, occurs in the Eagle collapse center at Hardscrabble Mountain. Here, the Triassic-Permian State Bridge Formation is abnormally thick, reflecting an outflow of underlying evaporite. On the west side of the Carbondale collapse center, structural wedging formed the west-dipping Grand Hogback monocline during early Tertiary Laramide deformation close to the western margin of the late Paleozoic central Colorado trough. Uplimb thrusts beneath the steep face of the monocline provide evidence of backthrusting. The presence of the Roaring Fork diapir proximal to the point of greatest curvature of the Grand Hogback monocline at the Leadville reflector level suggests that diapirism may have begun during formation of the monocline. Evidence for late Cenozoic evaporite tectonism is observed in all the seismic lines in spite of the difficulty of imaging shallow, young deposits that record evidence of abundant late Cenozoic evaporite tectonism observed during geologic mapping.