Abstract

The Tathlina area comprises the plains and uplands and part of the adjacent mountain belt lying to the west of Great Slave Lake in the southernmost Northwest Territories. Strata underlying the plains and uplands are mainly of Devonian age, obscured in part by remnants of a thick Cretaceous cover. This sedimentary section thickens westward into the mountain belt where a succession ranging through Cambrian, Ordovician, Silurian, Devonian, and Carboniferous occurs. Toward the east, in the vicinity of Great Slave Lake, the wedge of sediment borders the Canadian Shield.

In the plains area the structure of the beds seems to be controlled by faulting in the Precambrian basement. By contrast, the mountain belt is characterized by open folds and thrust faults that originated in the Laramide orogeny.

Numerous indications of the presence of oil and gas in the area have been observed and, though excellent reservoir beds, including reefs, are widely distributed, exploration has proceeded at a slow pace. Drilling density is low, and large areas, particularly in the northern part of the region, remain unexplored.

There are three Middle Devonian gas fields in the Tathlina area and some wells which have yielded substantial flows of gas from the Upper Devonian. Further development can be expected when pipeline facilities become available.