--> ABSTRACT: Breached Madison (Mississippian) Unconformity Trap, Northwestern Colorado, by John Dolson, F. Blume; #91002 (1990).

Datapages, Inc.Print this page

ABSTRACT: Breached Madison (Mississippian) Unconformity Trap, Northwestern Colorado

John Dolson, F. Blume

Madison carbonates along the northern plunge of the Sierra Madre Uplift in northwestern Colorado are saturated with tar along a regional unconformity trap. Migration occurred beneath a pre-Phosphoria (Permian) surface through Weber and younger formations.

This erosional surface is responsible for trapping 350+ MMBOE of unconformity-related production in the Minnelusa Formation of the Powder River basin and 8+ BBOE of tar deposits in the White Rim Sandstone (Permian) of Utah.

Seismic delineation of this wedge edge is difficult, but its limit appears controlled in part by the location of pre-existing faults. The apparent lack of bottom seals and steep structural dip in western Wyoming and Colorado make this stratigraphic trap a high-risk play. Both the problems and potential of exploration for similar subsurface trends are illustrated through examination of the geology of this tar seep.

AAPG Search and Discovery Article #91002©1990 AAPG Rocky Mountain Section Meeting, Denver, Colorado, September 16-19, 1990