Seismic Evidence of Tectonic Influence on Development of Cretaceous Listric Normal Faults, Boulder-Wattenberg-Greeley Area, Denver Basin, Colorado

Reflection seismic studies in the Denver basin near Greeley, Colorado, illustrate an association between listric normal faults (which sole out in detachment or decollement zones) and basement-controlled faults. Recurrent movement on basement-controlled faults triggered development of listric normal faults in tectonically sensitive stratigraphic intervals of the Cretaceous. Stratigraphic intervals exhibiting listric normal faults include the Cretaceous Laramie-Fox Hills-Upper Pierre, Middle Pierre Hygiene zone, and the Niobrara-Carlile Greenhorn. Listric normal faults are prevalent on the flank of a fault-bounded basement-controlled paleostructural block termed the Wattenberg block by Weimer and Sonnenberg (1982). Listric normal faults influence Cretaceous reservoir systems in the Hambert field area on the north flank of the Wattenberg-Greeley Lineament Zone.