Abstract: The Influence of Cyclicity and Varied Topography on Virgil and Wolfcamp Sedimentation in the Denver Embayment, Eastern Colorado

RALL, ELIZABETH P.

The Late Paleozoic Denver Embayment was a shallow extension of the petroliferous Hugoton Embayment and Anadarko Basin. Systems tracts in these contiguous troughs record eustatic sea level cycles, sequential basin filling, climatic changes, and tectonic activity associated with the Ouachita Orogeny. Depositional patterns in the Denver Embayment were also influenced by local physiographic environments. 1) Fountain fanglomerates were trapped in half grabens paralleling the Ancestral Rocky Mountain front; 2) a carbonate factory (Virgil) and evaporite basin (Wolfcamp) developed in clearer water on the Transcontinental-Arch; 3) a deltaic complex expanded north and east from the Apishapa Uplift; and 4) typical Midcontinent cyclothems were deposited in the distal Hugoton Embayment. Two orders of cyclicity are recognized. Major transgressions of a longer-term cycle are separated by a late Virgil unconformity. Numerous shorter-term Midcontinent-type cyclothems in the Virgil and less well organized sequences in the Wolfcamp are superimposed on the longer cycle.

During the Laramide Orogeny the gentle southeast plunge of the Denver Embayment was rotated, creating the modem Denver Basin and Las Animas Arch Hydrocarbon traps are largely unaltered at the north end of the Denver Basin but to the south where dip was reversed, new traps formed for possible late migrating hydrocarbons.

AAPG Search and Discovery Article #90946©1997 AAPG Rocky Mountain Section Meeting, Denver, Colorado