The Yurso Vein occurrence is located in a pass at the head of a creek approximately 4 kilometres southeast of Beale Lake, 75 kilometres northeast of the community of Dease Lake.
The Beale Lake area, bordering the northeast side of the Lower Cretaceous Cassiar Batholith, is largely underlain by the Sylvester Allochthon, a stack of thrust sheets of oceanic to pericratonic arc affinity that overlies the para-autochthonous Cassiar terrane. South of Beale Lake, large parts of the Mississippian to Permian Upper Dorsey assemblage are dominated by green and grey phyllite and quartzite (Precambrian-Devonian Rapid River tectonite).
The Yurso vein outcrops in the pass at the head of the creek, where it has been traced as subcrop over 1000 metres along a northwest strike. The Yurso quartz vein contains arsenopyrite, pyrite, stibnite and tetrahedrite. Analyses show it to be highly anomalous in a broad suite of metals, including gold (to 1250 parts per billion), silver (to 1824 grams per tonne), bismuth (to 413 parts per million), lead (to 23,000 parts per million) and antimony (to 8000 parts per million), as well as selenium, tellurium, copper and zinc (Fieldwork 2001, page 55).
Heavily oxidized vein fragments of secondary base metal sulphates and carbonates, such as anglesite and smithsonite, are abundant in float downslope from the projected vein trace. The largest pieces of vein material are 20 to 30 centimetres in their shortest dimension. The fracture that hosts the Yurso vein is also occupied by granite porphyry dikes that contain round quartz and orthoclase megacrysts. They may be offshoots from the nearby Lower Cretaceous Cassiar Batholith, or younger, late Cretaceous Eocene intrusions. Some show strong argillic alteration, which also affects phyllite and quartzite of the Mississippian to Permian Upper Dorsey assemblage (Precambrian-Devonian Rapid River tectonite) around the vein.
The vein occurrences (No Fish vein (MINFILE 104I 122) and Yurso vein) are on strike with, and 2 to 5 kilometres southeast of the Beale Lake vein set (MINFILE 104I 098). They suggest that it may extend through the low-lying country around Beale Lake and, potentially, onto map sheet 104I/15. The granite porphyry dikes that accompany them lend strength to the inferred connection between late plutonic activity and gold mineralization (Fieldwork 2001, page 55).
Work History
In 2001, the Yurso vein was discovered by Joanne Nelson during a regional mapping program for the British Columbia Geological Survey.
During 2003 through 2005, the area was held by Sutcliffe Resources Ltd. as part of the Beale Lake property. See the Keel (MINFILE 104I 098) occurrence for a complete summary of this work.
In 2006, Sutcliffe Resources Limited conducted a preliminary prospecting and rock sampling on the Yurso vein. A small grid totalling 4.95 line-kilometres was established over the area of vein float and 178 rock samples were collected from the grid. Grab samples of mineralized vein material, from the southeastern end of the mineralized veined zone, yielded values of up to 2.75 grams per tonne gold, 3050 grams per tonne silver, 21.7 per cent lead, 7.12 per cent antimony and 0.084 per cent bismuth, whereas other samples taken up to approximately 900 metres to the northwest yielded up to 0.79 gram per tonne gold, 454 grams per tonne silver, 5.36 per cent lead and 4.65 per cent antimony (Assessment Report 28965).
In 2017, Jedway Enterprises Ltd. conducted a geological program of air photograph interpretation at a scale of approximately 1:8572 using Google Earth photos and BC TRIM maps from www.MapPlace.gov.bc.ca covering the main portion of the Yurso property where the mineralized veins and gravity anomaly occur. Interpretation and analysis of the linear features in the air photograph coupled with the location of anomalous rock samples collected in 2006 by Sutcliffe Resources Limited indicate that the mineralized tetrahedrite-arsenopyrite-stibnite-pyrite vein on the Yurso is not continuous, but occurs in three segments closely spatially related to northeast-trending faults.
