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Recognition of depositional sequences and stacking patterns, Late Devonian (Frasnian) carbonate platforms, Alberta basin

Conference · · AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States)
OSTI ID:6455497
Six depositional sequences bounded by regional unconformities or their correlative equivalents (sequence boundaries) have been recognized in Late Devonian (Frasnian) carbonate platforms in the Alberta basin. These sequences consist of a predictable vertical succession of smaller scale shoaling-upward cycles (parasequences). Parasequences are arranged in retrogradational, aggradational, and progradational stacking patterns that can be modeled as a sediment response to relative changes in sea level. Sequence boundaries are recognized by onlap onto underlying shelf or shelf margin strata. This onlap includes shelf margin wedges and deep marine onlap. In outcrop sections shelf margin wedges exhibit an abrupt juxtaposition of shallow water facies over deeper water deposits with no gradational facies changes at the boundaries. High on the platform, subaerial exposure fabrics may be present. The shelf margin wedges are interpreted to have formed during lowstands in sea level and typically exhibit an aggradational stacking pattern. On the platform, two types of sequences are recognized. A type 1 cycle occurs where the sequence boundary is overlain by a flooding surface and subsequent parasequences exhibit retrogradational stacking. In a type 2 cycle the sequence boundary is overlain by an aggradational package of shallow water parasequences, followed by a retrogradational package. These two types of sequences can be modeled using a sinusoidal eustatic sea level curve superimposed on thermo-tectonic subsidence.
Research Organization:
Exxon Production Research Co., Houston, TX
OSTI ID:
6455497
Report Number(s):
CONF-870606-
Conference Information:
Journal Name: AAPG (Am. Assoc. Pet. Geol.) Bull.; (United States) Journal Volume: 71:5
Country of Publication:
United States
Language:
English