The Black Creek prospect explores one of several mineral deposits in a belt south of Valdez Creek. The Valdez Creek area is underlain by pre-Upper Triassic pelitic clastic rocks, minor tuff, limestone lenses, and conglomerate. The rocks apparently vary abruptly in regional metamorphosed grade, from prehnite-pumpellyite through greenschist and amphibolite, to granulite. These rocks are intruded by Upper Jurassic alkali gabbro and by dioritic intrusions of Late Cretaceous and Early Tertiary age (Smith, 1981).

The bedding and foliation of the strata strike about N 75 E and dip steeply northwest. Strike-slip faults having a similar orientation are also present, particularly on the south side of Valdez Creek (Smith, 1981). On the north side of the creek, a northwest-dipping thrust fault in part explains an apparent 'telescoping' of the metamorphic rocks.

The Black Creek deposit apparently consists of sulfide-bearing, locally auriferous quartz veins in sheared, brecciated, and altered sedimentary and dioritic intrusive rocks. The sulfide minerals include arsenopyrite, pyrite, and pyrrhotite. Recurrent movement along faults, pulses of hydrothermal alteration, and recurrent injection of quartz veins has produced complex geology in the prospect area (Smith, 1981). The prospect area is rust stained in the vicinity of the adit due to the oxidation of iron sulfide minerals. There is a gold and arsenic geochemical anomaly around the prospect area.