Alkalic porphyry style Au-Cu deposits of the Cadia district are associated with
Late-Ordovician monzonite intrusions, which were emplaced during the final phase of
Macquarie Arc magmatism at the end of the Benambran Orogeny. N-striking faults,
including the curviplanar, northerly striking, moderately west-dipping basement thrust faults of the Cadiangullong system, developed early in the district history. NE-striking faults formed during rifting in the late Silurian. Subsequent E-W directed Siluro- Devonian extension followed by regional E-W shortening during the Devonian
Tabberabberan Orogeny dismembered these intrusions, thereby superposing different
levels porphyry Au-Cu systems as well as the host stratigraphy.
During the late Silurian, the partially exhumed porphyry systems were buried
beneath the Waugoola Group sedimentary cover sequence, which is generally preserved
in the footwall of the Cadiangullong thrust fault system. The Waugoola Group is a
typical rift-sag sequence, deposited initially in local fault-bounded basins which then transitioned to a gradually shallowing marine environment as local topography was
overwhelmed. Basin geometry was controlled by pre-existing basement structures, which
were subsequently inverted during the Devonian Tabberabberan Orogeny, offsetting the unconformity by up to 300m vertically. In the Waugoola Group cover, this shortening
was accommodated via a complex network of minor detachments that strike parallel to
major underlying basement faults. For this reason, faults and folds measured at the
surface in the sedimentary cover can be used as a predictive tool to infer basement
structures at depth.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/1064 |
| Date | 11 1900 |
| Creators | Washburn, Malissa |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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