Record Details
Structural geology of the Mount Polley Cu-Au district, south-central British Columbia
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Structural geology of the Mount Polley Cu-Au district, south-central British Columbia |
| Names |
Wafforn, Stephanie R.
(creator) Dilles, John H. (advisor) Meigs, Andrew J. (advisor) |
| Date Issued | 2013-07-11 (iso8601) |
| Note | Graduation date: 2014 |
| Abstract | The Mount Polley copper-gold deposit is one of a series of porphyry copper deposits that occur in a belt of accreted Mesozoic age island arc terranes in the Canadian Cordillera. The deposit comprises three breccia-hosted Cu-Au ore zones that are associated with a series of monzodiorite to monzonite intrusions emplaced into the Nicola Group in the Late Triassic. The Mount Polley deposit has been deformed in a number of structural events and the relative sequence of folding, faulting, and tilting provides insight into the tectonic history of the Quesnel Terrane. During a period of 8 million years, from 205 Ma to 197 Ma, the Mount Polley deposit was emplaced into the Nicola Group, exhumed to the surface, and buried beneath a sequence of conglomerates, sandstones, and a quartz latite ignimbrite. The oldest faults in the district are the north-northwest-striking reverse faults. These include the Polley Fault and East Cariboo Fault, which displace intrusions, mineralized ore zones, and plagioclase and K-feldspar porphyry dikes. Reverse faults are coeval with a regional folding event that formed a doubly plunging synform that dips to the northwest in the Mount Polley district. The North Springer Fault is a southwest-striking sinistral fault that cuts the Polley Fault and the East Cariboo Fault. The youngest faults in the district are the Green Giant Fault and the Center Fault, which is inferred from drill hole data. The Green Giant Fault cuts the intrusions, mineralized ore zones, and both porphyry dikes and post-mineral dikes. A tilting event of unknown age resulted in a 30-35° NW tilt of the sedimentary beds, ore bodies, and dikes in the Mount Polley district. A limited number of apatite fission track data suggest that the district cooled through the apatite partial annealing zone during the Paleocene to Eocene. This study provides insight into the local structural geology of the Mount Polley Cu-Au deposit, and the history of island arc accretion, hinterland development, and post-convergence extensional modification of allochthonous terranes in the Canadian Cordillera. |
| Genre | Thesis/Dissertation |
| Access Condition | http://creativecommons.org/licenses/by-nc/3.0/us/ |
| Topic | Geology, Structural -- British Columbia -- Mount Polley Region |
| Identifier | http://hdl.handle.net/1957/43346 |
