--> Abstract: Low-Temperature Thermochronology of the Port au Port Peninsula Area, Western Newfoundland, Derived from Inversion of Apatite Fission Track Data: Implications for Hydrocarbon Exploration and Prospectivity in a Paleozoic Frontier Basin, by Glen S. Stockmal, Dale R. Issler, Alexander M. Grist, and Art Slingsby; #90039 (2005)

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Low-Temperature Thermochronology of the Port au Port Peninsula Area, Western Newfoundland, Derived from Inversion of Apatite Fission Track Data: Implications for Hydrocarbon Exploration and Prospectivity in a Paleozoic Frontier Basin

Glen S. Stockmal1, Dale R. Issler1, Alexander M. Grist2, and Art Slingsby3
1 Natural Resources Canada, Calgary, AB
2 Dalhousie University, Halifax, NS
3 Piper Energy Inc, Calgary, AB

Port au Port #1, the first of six new wells drilled in the Port au Port Peninsula area of western Newfoundland in the latest round of hydrocarbon exploration that began in the early 1990s, yielded 51 API oil from a structural trap in Ordovician platform carbonates, in the footwall of a thick-skinned fault inverted during Acadian (Devonian) orogenesis. We have reassessed the low-temperature thermochronology of the area to constrain the timing of structural trap development versus hydrocarbon maturation using state-of-the-art apatite fission track (AFT) inverse time-temperature modeling to yield a set of thermal histories that fit observed AFT ages and length distributions. Other maturation indicators and the geological history provide additional critical modeling constraints.

Results indicate that following syn-orogenic burial and post-orogenic unroofing, all AFT samples were heated into the partial annealing window (~60-120 °C) in post-Visean times, due to burial beneath the regional Maritimes Basin. However, the magnitude and timing of peak temperature are dependent upon structural position with respect to the inverted thick-skinned faults associated with structural traps. At the deepest stratigraphic levels within the Cambro-Ordovician platform, in the immediate hanging walls of these faults, peak temperatures occurred prior to fault inversion, i.e., during Acadian orogenesis. At equivalent stratigraphic levels in the thrust footwalls, and at shallower levels in both footwalls and hanging walls, peak temperatures were not achieved until post-Visean burial beneath the Maritimes Basin. Peak thermal maturity therefore post-dated the late Acadian development of large, thick-skinned structural traps, and these structures therefore have high potential prospectivity.

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