Altin / Surprise Lake
Location: Northern British Columbia (Atlin Mining District)
Ownership: 100% Gray Rock
Size: 5,242 ha
Recent Discoveries May Indicate Lode Source of Placer Gold
For over 100 years, prospectors and miners in the Atlin area of northern BC have sought the lode source of the region’s abundant placer gold. Recent discoveries, backed by a 2016 BC Geological Survey study, indicate that a key source of this gold may lie within Gray Rock’s Surprise Lake property.
The Surprise Lake project is located eight kilometers east of the town of Atlin in northwestern British Columbia, a productive placer mining area with a rich mining history dating back to the gold rush of the 1890’s. Atlin Lake ranks as the second largest producer of placer gold in the province. Large parts of the property are situated within the drainage basins of several prolific gold placer streams such as Pine Creek and Spruce Creek which are actively being mined. The property is defined by four contiguous project areas: Birch, Surprise Lake, Otter Creek and Idaho Peak.
Access is by the Surprise Lake road, east of Atlin for 10 km, as well as many logging and placer trails that branch out from this main road. Pine Creek flows through the centre of the property and is characterized by a wide flat valley flanked by rounded mountains to the north and south.
A two-phase exploration program is recommended for the property. The first phase would include of property-wide reconnaissance exploration including the preparation of a NI 43-101 technical report as well as detailed work on the Surprise Showing and Otter Creek placer. The second phase would consist of diamond drilling of targets developed during the initial phase. The second phase would be contingent on receipt of favourable results from the first phase.
Regional Exploration History
Exploration in the Atlin region dates back to the discovery of gold on Pine Creek in 1897. Many of the local gold occurrences were identified at the turn of the twentieth century providing the first regional overview and tectonic synthesis. To date, most of the exploration success has led to the identification of prolific placer mining operations.
Since that time exploration for lode-gold mineralization has been ongoing with varied success. The goal of past and present studies has been to locate the major sources of the placer gold which permeates the local waterways. Comparative studies of the mineralogical and chemical characteristics of both placer and lode gold have conducted to investigate trace element signatures related to listwanitic alteration halos to identify potential pathfinder elements indicative of gold mineralization. Additionally numerous studies have been undertaken to understand the surficial geology of the area.
Results from a large volume volume of exploration work conducted in the immediate area are documented in assessment reports filed with the provincial government by mining and exploration companies. These reports include details of trenching, drilling and sampling programs as well as mapping and geophysical surveys.
Notable examples include a diamond drilling and bulk sampling program which was carried out on the nearby Yellowjacket gold showing. Many high grade gold intersections were reported by Prize Mining Ltd. from this “listwanite – hosted” showing. Additionally, a feasibility study was carried out on the Ruby Creek molybdenum prospect, which adjoins the Surprise Lake property to the northeast. Adanac Molybdenum Corporation Ltd. reported a resource of 213 million tonnes with a grade of 0.063% of Molybdenum from this prospect. The prospective ophiolite assemblage and the adjacent carbonatized ultramafic rocks underlie large parts of the Surprise Lake property. Listwanites have also been identified at the Surprise showing.
The Surprise showing consists of a band of listwanites that occurs on the northeast flank of Spruce Mountain. The primary showing is a quartz vein emplaced in andesite and measures up to six meters in width, Exploration, prior to 1925, of this quartz vein with an adit revealed minor amounts of argentiferous galena, pyrite, chalcopyrite and siderite. Sampling in 1982 of this showing by Standard Gold Mines Ltd. returned values of 0.042 ounces per ton (1.27 g/t) of gold and 1.20 ounces per ton (36.58 g/t) of silver.
A series of bulldozer trenches exposes a carbonatized serpentinite (Listwanite) containing pyrite and pervasive mariposite. As part of a larger program carried out by Standard Gold Mines Ltd., a total of 10 rock “chip” samples were collected for assay from various rock types, quartz veins, rust-stained boulders and mariposite-stained carbonatized rock at the Surprise Showing. Most of these were collected on ground now covered by the Surprise Lake Property. Standard Gold Mines also did two short lines of VLF-EM and a limited contour soil-sampling program over a small part of the Surprise Showing area.
In 1985, the Surprise Lake Exploration Syndicate carried out a 7 line-kilometer ground magnetometer and VLF survey to investigate anomalies detected by a Dighem Survey in 1984. Strong magnetic responses typical of unaltered ultramafic or volcanic rock were delineated. Several discontinuous VLF anomalies were also outlined.
During 2006 and 2007, Double Crown Ventures Ltd. carried out geophysical and geochemical surveys as well as prospecting over parts of the property. The studies included helicopter-borne Furgo (Digehem) Electormagnetic and magnetic geophysical surveys as well as geophysical and geochemical surveys over several grids. This work delineated a number of anomalies over a belt of listwanites on the Surprise prospect.
Between 2010 and 2014, the Birch and Spruce Mountain areas of the property were subject of several Mobile Metal Ion (MMI) soil sampling programs which yielded anomalous values for gold and copper.
In 2015, an MMI study was carried out on the Otter Creek block of the property be DeCoors Mining. A total of 489 samples were collected at 25 meters intervals along 14 parallel lines, 100 meters apart covering approximately 12.9 line kilometers.
In July 2016, visible gold was found during a rock sampling grogram within the bedrock along Otter Creek producing assay values as high as 42.1 g/t Au. The gold was hosted by quartz vein stockwork and variably pyritic pale green and graphitic phyllite wall rock, proximal to the northerly trending Otter Creek Fault. Studies of this bedrock are currently underway by the BC Geological Survey to determine the age, petrology and geochemical associations. The extent of this mineralization is the primary focus of the current property exploration.
The property hosts ultramafic peridotite in an arcuate thrust slice in the northwestern part of the property and as small lenses in the southeast. Provincial examples of gold camps with spatially associated ultramafic rocks include the Bridge River, Cassiar and Rossland lode gold and the Atlin and Dease Lake placer camps. Additionally, the Surprise Lake Property covers four documented mineral occurrences on file with the British Columbia Geological Survey (Surprise, Atlin Project (Main Block), O-1 and Cabin Silver), and the recent discovery in July, 2016 of visible gold in bedrock along Otter Creek. The gold is hosted by quartz vein stockwork and variably pyritic pale green and graphitic phyllite wall rock, proximal to the northerly trending Otter Creek Fault. Studies of this bedrock are currently underway by the BC Geological Survey to determine the age, petrology and geochemical associations. The extent of this mineralization is the primary focus of the current property exploration.