New sedimentological, petrofacies, and palynological data from the Colorado Creek basin (CCB) help evaluate the displacement history of the 2000-km-long Denali fault system (DFS). The CCB consists of ~455 m of Cenozoic strata that are bound by thrust faults oriented subparallel to the McKinley segment of the DFS. AGE – The age of the CCB was previously interpreted as Paleocene on the basis of sparse plant megafossils. Palynological analysis of mudstones (n=9) from a continuous stratigraphic section indicates early Oligocene deposition. DEPOSYSTEMS – Measured stratigraphic sections document two lithofacies associations. The lowermost 350 m of strata consist of imbricated, clast-supported conglomerate, cross-stratified sandstone, and carbonaceous mudstone interpreted as stream-dominated alluvial fan deposits. The uppermost 55 m of strata consist of lava flows, tuff, and pumice interpreted as subaerial volcanic deposits. PROVENANCE – Conglomerate clast counts (n=1012) document mainly sedimentary (71%) and igneous (15%) clast types. Source-diagnostic clasts in combination with southeastward-directed paleocurrent indicators (n=47) suggest that detritus was derived from local source terranes exposed along the DFS. BASIN DEVELOPMENT – New data from this study indicate that the CCB formed as a transpressional basin during the early Oligocene, concurrent with strike-slip faulting along the DFS. From a regional perspective, development of the CCB was synchronous with dextral displacement and strike-slip basin development along the DFS in southwestern Alaska, British Columbia, and Yukon Territory. Collectively, the presence of these basins indicates a major phase of late Eocene-Oligocene displacement along the DFS.