Anticosti
Geology

ANTICOSTI

Anticosti is one of three large sedimentary basins in Quebec with oil potential. Basic exploration work carried out in the basin (19 oil wells and 3 coreholes drilled) has helped reinterpret the geology to identify other potential targets.

Analysis of the results obtained is not yet complete. We are investing in further stratigraphic drilling and analysis to determine the quantity of potentially recoverable hydrocarbons and identify the best techniques for extracting them. The results of the new analyses will help us assess the project's profitability.

Geology of Anticosti Island

Anticosti Island is part of a Lower Paleozoic sedimentary basin that encompasses all of the island's surface and subsurface rock down to the Canadian Shield's Precambrian basement. The sedimentary basin extends northward beneath the Gulf of St. Lawrence to the North Shore and into the Havre-Saint-Pierre region, to the east almost to Newfoundland, and to the south and west to a fault zone under the St. Lawrence, which separates it from the Appalachians.

The sedimentary rock in the basin was deposited in an ancient ocean (Iapetus Ocean) on the southern edge of Laurentia, the North American protocontinent. The sedimentation phase extended over a period of some 50 million years between the Lower Ordovician (485 Ma) and Lower Silurian (435 Ma). To the south of the island, at depth, the rock formations are thicker than in the north. These variations in sediment thickness are due to a deepening of the sedimentary basin toward the south, resulting in more material being deposited there. The strata are slightly inclined toward the south, resulting in greater sediment thickness being conserved.

Sedimentation was not however continuous throughout the time period. Deposits in the lower, older part of the basin were interspersed with periods of inactivity during which deposited rock was dewatered and eroded, and other periods in which sedimentation ceased without erosion. The sedimentation on the upper part of the basin does not seem to have been subject to comparable interruptions.

The rock bears witness to several stages in the development of Laurentia's continental margin. In an early stage, a continental shelf formed on the outer edge of the Laurentian continent, which then straddled the equator. Most of the sediment deposited on the shelf was formed of limestone. This early stage was followed by a period of exhumation and erosion. Limestone sedimentation subsequently continued until the Upper Ordovician, followed by periods when the limestone was replaced by clay rock.

The next phase, also in the Upper Ordovician, involved the sedimentation of the Macasty Formation's organically rich black clays. This phase corresponds to the climax of one of the tectonic phases in Appalachian mountain building (called Taconic orogeny) when the Iapetus Ocean began to close following convergence of the Laurentia and Gondwana tectonic plates.

The subsequent layers, consisting of consolidated muds, sandstone, and limestone, correspond to the destruction and erosion of rock uplifted by the Taconian orogeny and establishment of another continental margin in an intracratonic basin. The Silurian sedimentation comprises mainly limestone.

Anticosti basin rocks have not been very “folded over” and are affected by only a few major faults. Overall, the strata are inclined toward the southwest with a 1° to 2° slope forming a cuesta inclined toward the south. A number of relatively minor faults affect the strata on the upper part of the basin but do not cross the top of the sedimentary sequence.

In 2011, Sproule Associates Limited established a best estimate (P50) of 33.9 billion barrels of oil equivalent in undiscovered resources initially-in-place for the licenses held. Sproule's assessment was for the 38 licenses held by Petrolia and Corridor Resources, which are now part of Anticosti Hydrocarbons assets, and based on analysis of several wells.