2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 179-11
Presentation Time: 11:10 AM

TECTONIC DEFORMATION OF THE PANDORA PEAK UNIT INFERRED BY FOLDING AT HARLING POINT, VICTORIA, BC:  IMPLICATIONS FOR THE PACIFIC RIM TERRANE


MCEWEN, Gerri L., School of Earth and Ocean Sciences, University of Victoria, Bob Wright Center, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada and JOHNSTON, Stephen T., School of Earth and Ocean Sciences, University of Victoria, Bob Wright Centre, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada, gerri.mcewen@gov.bc.ca

Vancouver Island is composed of a series of crustal blocks that formed in the Paleo-Pacific ocean basin and were thereafter accreted to the western margin of North America. The Pacific Rim Terrane (PRT) lies along the western margin and wraps around the southern tip of Vancouver Island. It is composed of Mesozoic volcanics and sediments and is divided into three components: the Pacific Rim Formation (PRF), the Leech River Complex (LRC), and the Pandora Peak Unit (PPU). For this study, small scale mapping and structural analyses were performed on a segment of the PPU at Harling Point in Victoria, BC. The PPU records the interaction of the PRT with the older inboard Wrangellia terrane which makes up the majority of Vancouver Island. It was found that the rock units represented in the Harling Point outcrop are characteristic of ocean floor volcanics with an overlying blanket of sediments. These rocks were scraped off, folded, and thrust northward as they were driven against a wedge of Wrangellian crust, a process known as tectonic wedging. The final result was a north-verging folded thrust nappe deformed by asymmetric south-verging folds. The next step in the process is to apply and refine this model by analyzing additional outcrops of the PPU throughout Vancouver Island.
Handouts
  • TECTONIC DEFORMATION OF THE PANDORA PEAK UNIT INFERRED BY FOLDING AT HARLING POINT, VICTORIA, BC IMPLICATIONS FOR THE PACIFIC RIM TERRANE.pptx (21.6 MB)