Clinton Creek asbestos deposit is situated at 77 km northwest of Dawson City on Clinton Creek in Yukon. Yukon Metamorphic Complex of Ordovician to Devonian age covers most of the Clinton Creek area. The most prominent metamorphism of the area occurred in Permian time. Based on intensity and style of deformation of ultramafic bodies and country rocks it is suggested that the ultramafic rocks were emplaced probably during the Permian period. Tintina fault is a weak zone along which the alpine ultramafic bodies of Clinton Creek and probably some of the others along and close to the Tintina Trench were tectonically emplaced. These were later folded and metamorphosed with the country rocks. During latest Cretaceous-earliest Tertiary time the area was intruded by acid intrusive rocks. The youngest undeformed and fresh basalt is probably of Selkirk volcanics equivalent. Three prominent phases of deformation were delineated. Probably the oldest and most complex phase occurred during the Permian, along with the initial movement of the Tintina fault. Small, tight, isoclinal folds are characteristics of this phase. The structural trend is roughly parallel to the direction of the Tintina Trench. Due to later deformations changes in direction of fold axes of this phase is common. The second phase of deformation gave rise to large recumbent folds with southerly vergence. Third phase of deformation gave rise to antiform structure of regional scale.
The Porcupine and Snow Shoe ultramafic bodies are mined for chrysotile asbestos. A few other ultramafic bodies contain appreciable amount of chrysotile-fibre but not of adequate quantity to be mined. Most of the ultramafic bodies are sheared or massive, and are devoid of known chrysotile-fibre. Chrysotile-fibre bearing serpentinized ultramafic masses within argillite unit or at the contact of argillite and other units seem to carry ore grade or substantial amount of chrysotile-fibre. Evidence of Clinton Creek asbestos deposit mainly supports formation of chrysotile-fibre as fracture filling. Although evidence of fracture filling rather than replacement seems convincing and exists on a wide scale, a few evidence indicates replacement characteristics on minor scale. The main phase of mineralization is believed to occur at the end of Cretaceous when acid intrusive rocks intruded the vicinity of the Clinton Creek area. These intrusions could have provided warm aqueous solution to react with the existing serpentine along fractures. This resulted deposition of chrysotile-fibre in an essentially closed system. Analysis of isotopic dates of the Yukon Crystalline Plateau shows a distinct grouping of igneous activity at mid Cretaceous and latest Cretaceous time.
A copy of this thesis is available at the EMR Library – QE195 H86.
This thesis is available online at https://open.library.ubc.ca/cIRcle/collections/ubctheses/831/items/1.0052868.
