The Origin of the Gold Creek Collapse Structure and Associated Dolomitization, West Central Alberta

Kent R. Barrett
Anadarko Canada, Calgary, AB

The Gold Creek Gas Field has produced 100 Bcf of gas plus natural gas liquids from the Upper Devonian Wabamun Formation. The Wabamun is a 220m thick limestone that is only productive where it has been dolomitized. Dolomite distribution is fault controlled.

These faults are associated with a significant episode of structural sag that has resulted in up to 90m of relief on the Wabamun surface. Associated with this subsidence is compensatory thickening of the Mississippian Debolt Formation. The mechanism of collapse appears to be differential compaction within the underlying Devonian Leduc reef. The muddy lagoonal sediments of the Leduc reef interior underwent more stylolitization than the coarser grained reef margin in response to overburden pressure. Rapid subsidence of the Leduc reef interior occurred during Debolt deposition. This rapid subsidence induced faulting that extended upwards from the Leduc, through Wabamun and into the Mississippian section. These faults allowed the upward flow and escape of CaCO₃ saturated formation waters from the Leduc reef, resulting in an acceleration of reef collapse.

Later, during dolomitization of the underlying Leduc reef, the collapse induced faults provided conduits for the dolomitization of the Wabamun Formation.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005