CENOZOIC LANDSCAPE EVOLUTION OF THE CENTRAL ROCKY MOUNTAINS: INTERPLAY OF TECTONICS, CLIMATE, AND SURFACE PROCESSES

Recent progresses in understanding Cenozoic histories of tectonic, climate, and surface processes in the central Rocky Mountains (Rockies) allow the use of a comprehensive model to depict the landscape evolution of the region. Here we use previously developed TISC (Tectonics, Isostasy, Surface Processes, and Climate) models to demonstrate the evolution of landscapes in the central Rockies from the latest Cretaceous to present, and test the hypotheses that the enhanced erosion that shaped the most recent landscape of the central Rockies was caused by late Neogene global cooling, renewed latest Miocene tectonic uplift, or both.

The models integrate tectonics, climate, and surface processes derived from geologic records, and produce drainage patterns that should be matched with known paleodrainage patterns. We focus on key time intervals to catch the influence of major tectonic and climatic events on landscape during the Cenozoic. Models produced for 70, 60, and 50 Ma show that the pattern and timing of the Laramide tectonics played the first order role on landscape evolution. Model results also show that small changes in climate parameters, such as precipitation and evaporation rates, caused drastic changes in erosion and drainage patterns, suggesting landscape in the central Rockies was also sensitive to climate during the early Cenozoic. Models produced for <50 Ma will bring new insight into landscape evolution of the central Rockies during the middle and late Cenozoic, whose geologic record are relatively scarce.