NOBLE, J. P. A., Department of Geology, Univ. of New Brunswick, Fredericton, NB, Canada; C. St. PETER, New Brunswick Dept. Natural Resources and Energy; and A. CHOWDHURY, Department of Geology, Univ. of New Brunswick, Fredericton, NB, Canada

ABSTRACT: Oil Formation and Entrapment in Relation to Burial History and Tectonic Development of the Lacustrine Moncton Subbasin, New Brunswick, Canada

Paleozoic tectonic events in the Moncton Subbasin of southern New Brunswick can be divided into 3 cycles, (1) the Horton cycle, (2) the Windsor-Hopewell cycle, and (3) the Cumberland-Pictou cycle. Each cycle is bounded by an unconformity and each comprises 3 parts, an initial phase of rapid fault controlled or thermal subsidence, a medial phase of moderate subsidence and a closing phase of compression or transpression, uplift and erosion.

The lacustrine Albert Formation was deposited during the Horton cycle and includes source rock oil shales and porous reservoir sandstones deposited in sandflats at the lake margin. Burial history reconstructions and thermal maturation modeling of the Albert Formation sediments indicate that most reached the oil window but show variable maturation because of different local fault tectonic histories. Peak hydrocarbon generation from type I organic matter occurred towards the end of the 2nd cycle and was followed by major uplift and erosion associated with the Enrage unconformity, resulting in the development of local structural and stratigraphic traps such as in the Stoney Creek field. The principal reservoir was formed prior to this uplift by secondary solution of feldspars and carbona es, as a consequence of type III organic maturation in the buried sandflat sediments. Maximum hydrocarbon conversion occurred in the areas of maximum subsidence and permanent lakes in the Lee Brook and Hillsborough areas.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.