The Snowbird property lies within the central Cache Creek Terrane (Figures 1 and 2). Late Paleozoic to Early Mesozoic oceanic rocks of the Cache Creek Terrain underlie the region and quartz diorite plutons of the Middle Jurassic Topley Suite of Intrusives locally intrude these rocks. The McKnab Lake Pluton is exposed in the western Snowbird claims and the Snowbird Stock Quartz Diorite to Tonalite cuts through Cache Creek sediments in the claims on the Sowchea Peninsula near the shore of Stuart Lake. The McKnab Lake Pluton was dated at 165.7 +2/-1 Ma and the Snowbird Stock has relict primary mineralogy similar to that of the McKnab Lake Pluton.
The Cache Creek Terrane extends more than 1,000 kilometres along the Canadian Cordillera through British Columbia. The Cache Creek Terrane is part of a composite super-terrane, accreted during the mid-late Jurassic when the westward North American plate collided with the Pacific Plate. To the east the terrane is intensely metamorphosed and deformed, and intrudes into the Omineca Crystalline Belt. In the west, the Coast Plutonic Complex was formed during the subduction and accretion events of the Cretaceous and Early Tertiary periods.
The regional Pinchi Fault and subsidiary, sub-parallel faults (Sowchea) formed during crustal accretion. Thrusting has occurred along the Sowchea Shear with ultramafics at surface proximal to the shear. The Pinchi Fault separates the Cache Creek Terrane from the Mesozoic Takla Group rocks to the east. Although blueschist facies rocks are seen in the Cache Creek Terrain in association with ultramafic harzburgites, no blueschist facies rocks are seen on the Snowbird claims, not even in rocks in contact with the harzburgites that underwent thrusting. This may suggest that rifting occurred prior to accretion or that the local thrusting of ultramafics along the Sowchea Shear occurred in a fault-bounded, curved or low pressure zone of the overall compressional fault regime. A spreading ridge within the Cache Creek Terrane came in contact with the craton during accretion, creating a transform fault. As a parallel structure to the Pinchi Fault, the Sowchea Shear may have behaved similarly and the ultramafics may have been exposed in a low-pressure zone pull-apart basin prior to thrusting.
There are many D2 fold axis, fault-shears that crosscut the overall Snowbird structural trend. Generally, rocks strike to the northwest and dip to the southwest, but in the mineralized zones at Snowbird the trend is for rocks to strike southeast and dip northeast. Locally, minor outcrops do strike parallel to D2 shears and dip in northerly or southerly directions.
The Quaternary cover in the Snowbird project area is comprised of glacial sediment deposited during the last glacial event. The predominant direction of ice advancement was from the east, followed by typical ice retreat that created glacial lakes. The Snowbird property has several different types of glacial deposits, which include boulder till, lacustrine clays and fluvial sediments. Percussion drilling on the eastern part of the property intersected lacustrine clays in excess of 55 m thick that are underlain by basal diamicton till. The depth to bedrock is generally between 12 and 16 metres.
Boulder tills dominate the western reaches of the claims and this adds complexity to mapping with little or no outcrop found. Much of the northern reaches of the claims, with the exception that are proximal to Stuart Lake, are covered by a mix of boulder tills, and fluvial sediments. The dominant overburden type varies greatly, even at a local scale. Throughout the property, large granite boulders, to as large as two metres, can be found sitting on top of outcrops of any rock type. The source of these boulders is likely the exposed intrusives to the east of Snowbird on both Mt. Beals and Shass Mountain.
The area surrounding the Snowbird property is underlain by oceanic crustal and sedimentary rocks that are intruded by Middle Jurassic tonalitic to quartz dioritic plutons. The area is dominated by pelagic sediments with lesser limestone, metabasalt, ultramafic and gabbroic units that form northwest-trending belts consistent with the regional structural grain of the central Cache Creek Terrane (Figure 3). The McKnab Lake pluton is exposed along the western property boundary. A smaller, satellite intrusion of altered quartz diorite to tonalite composition, the Snowbird Stock, cuts Cache Creek sedimentary and metavolcanic rocks on the peninsula near the west shore of Stuart Lake. There are also dikes in the area of the main Snowbird showing. Both the large intrusions are relatively undeformed elongate bod ies, oriented parallel to the regional structural grain.
The central low-lying area between the Snowbird deposit and the ophiolitic assemblage rocks to the east is underlain by a belt of continuous limestone. Similar resistant limestone blocks occur along a northwest trending ridge to the east of the Snowbird main showing, characterize this relationship. These limestones are typically light to dark grey, buff weathering, locally mottled and massive to laminated and commonly contain crinoids. It is unknown whether the dispersal of the limestone was a primary oceanic olistormal feature or resulted from later tectonism. Isolated occurrences of alkali volcanic basalt to the immediate north of the Snowbird are considered to also be derived from the belt to the east by a similar mechanism.
Metabasalt forms several prominent hills to the north and northwest of the Property and is also poorly exposed in the lowland area to the west. Basalts crop out in the area of the main Snowbird showing and are found in drill core, above and below the Sowchea thrust fault. These rocks are typically grey green, fine grained, aphanitic and massive. Locally, however, brecciated and rare pillowed structures are present. In some exposures the fine-grained aphanitic metabasalt grades into a slightly coarser grained, paler weathering diabasic phase of the unit.
Ultramafic rocks are best exposed near the southwestern boundary of the property within a klippe at the higher elevations of a northwesterly trending ridge. The summit of Mount Nielsp to the north is also interpreted as an isolated klippe of ultramafic rocks. In this area the ultra- mafic rocks are structurally underlain by a locally distinctive bedded clastic sedimentary succession, which has been interpreted to be Triassic and possibly Early Jurassic in age. The most southwesterly klippe is closely associated with the metagabbroic unit. Contact relationships are poorly exposed, however, the development of incoherent serpentinite with local carbonatization along discrete shear zones near the contact suggests it is faulted. The transition from ultramafic to mafic cumulate rocks into mafic volcanics displays a characteristic inverted ophiolite stratigraphy and can be interpreted to be the result of tectonic stacking. Ultramafic rocks also form slivers or tectonic lenses within the Sowchea thrust fault. These rocks range from completely serpentinized to completely carbonatized and lack any relict primary textures or mineralogies that indicate the original protolith.