Hydrocarbon
Source Rock Potential of the Whitehorse Trough, a Frontier Basin in Southern
Yukon, Canada
Lowey, Grant W.1 (1) Yukon Geological Survey, Whitehorse, YT
The Whitehorse Trough in southern Yukon is a frontier basin
that is thought to contain gas and possibly oil. It formed in the early
Triassic as an arc-marginal basin between the ancient North American margin to
the east and the volcano-plutonic Stikine Terrane to the west. Strata in the Trough consists of the Upper Triassic Lewes
River Group (informally subdivided into the Povoas and Aksala formations), the
Lower-Middle Jurassic Laberge Group (informally subdivided into the Richthofen,
Nordenskiold and Tanglefoot formations) and the Jura-Cretaceous Tantalus
Formation. Over 400 samples from these units have been analyzed by programmed
pyrolysis and combustion, which together with coal rank, vitrinite reflectance,
and the color of microfossils, indicates the following: the Povoas formation
has no source rock potential; the Aksala formation is a poor source rock,
probably gas-prone and postmature; the Richthofen formation is a poor to fair
source rock, gas-prone and postmature; the Nordenskiold formation has no source
rock potential; and the Tanglefoot and Tantalus formations are good to very
good potential source rocks, mainly gas-prone with a possibility of oil and
mature. Petroleum fluid inclusions are present locally in the Tanglefoot and
Tantalus formations. The Aksala and Richthofen formations are interpreted as
spent source rocks, whereas the Tanglefoot and Tantalus formations are
interpreted as potential source rocks and possibly effective source rocks. The
most prospective areas for hydrocarbon exploration in the Whitehorse Trough are
Division Mountain, Tantalus Butte and
Five Finger Rapids.