Large-scale hydrothermal zoning reflected in the tetrahedrite-freibergite solid solution, Keno Hill Ag-Pb-Zn district
The zoned Keno Hill vein system of central Yukon extends laterally from a Cretaceous plutonic-metamorphic center and surrounding quartz-feldspar veins, to carbonate-Ag-Pb-Zn deposits, and further to peripheral veins having epithermal characteristics. Seven distinct mineralogical zones are recognized...
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| Format: | Text |
| Language: | English |
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1989
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.512.616 http://rruff.info/doclib/cm/vol27/CM27_383.pdf |
| Summary: | The zoned Keno Hill vein system of central Yukon extends laterally from a Cretaceous plutonic-metamorphic center and surrounding quartz-feldspar veins, to carbonate-Ag-Pb-Zn deposits, and further to peripheral veins having epithermal characteristics. Seven distinct mineralogical zones are recognized, and the entire sequence is continuous from east to west in a 4O-km belt. The fault-and fracture-controlled veins are stratabound to the brit-tle moderately dipping Keno Hill Quartzite unit, of Mis-sissippian age. The unit is graphitic and appears to have acted as a large-scale hydrothermal aquifer, restricting fluid flow during minera1ization and " development of zoning predominantly to the lateral direction. Tetrahedrite is dis-tributed along a 25-km-Iong portion of the system, and is the principal ore mineral of Ag. Both Ag/Cu and Fe/Zn values in tetrahedrite are highest at the outer extremity of the system, where freibergite dominates over tetrahedrite; silver-rich samples are also distinguished by an overall increase in the number of cations per formula unit; the Sb / As value is high throughout. |
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