Anomalous concentrations of mercury occur in altered Triassic volcanics and sediments and in altered Tertiary volcanics. The anomalous zones lie in close association to Tertiary faults and proximal to Tertiary intrusive rocks. Epithermal activity during Tertiary volcanism and tectonism shows up as extensive hematite fracture-vein mineralization, anomalous gold, mercury and arsenic values and extensive gossans in the altered zones.
The oldest rocks in the DM showing area belong to the Upper Triassic Nicola Group and include andesite, dacite and carbonate-chert-sandstone units. The volcanics are often highly fractured and brecciated as a result of intense faulting. Epidotization and silicification is present to varying degrees in all the volcanics, occurring as erratic veinlets and as joint and fracture fillings. Brecciation is common along faults and fragments of Nicola volcanics are invariably cemented by carbonate, often containing visible cinnabar and/or hematite. In 1981, a single drillhole intersected a Tertiary subaerial sequence of coarse breccias and tuffaceous rocks. The upper third of the hole consisted of andesite polylithic laharic breccia with minor interbedded tuffaceous and basaltic flow horizons. An unusual concentration of earthy red hematite and ochre limonite occurs in the matrix. The lower two-thirds of the hole becomes more acidic in composition and consists of a sequence of dacite breccia and tuffs. This lower section exhibits the strong presence of a clay alteration zone. The entire hole is strongly fractured coupled with extensive hematization. Erratic mercury values occur throughout the drilled section and analysed up to greater than 10,000 parts per billion (Assessment Report 10215).
In 1979, a geochemical reconnaissance survey was conducted by Guichon Explorco Ltd. and resulted in several favourable gold-mercury-arsenic bedrock anomalies. In 1980-81, detailed followup by Guichon Explorco consisted of soil and rock chip geochemical surveys, geological mapping and one diamond-drill hole totalling 272 metres put down to test a favourable bedrock geochemical anomalous zone.
