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

Paper No. 65-13
Presentation Time: 4:00 PM

JURASSIC TO RECENT TECTONIC EVOLUTION OF NORTH AMERICA: A GPLATES MODEL


HENDERSON, Martha A., University of Victoria now with British Columbia Geological Survey, Ministry of Energy and Mines, PO Box 9320 Stn Prov Govt, Victoria, BC V8W 9N3, Canada, MIHALYNUK, Mitchell G., British Columbia Geological Survey, BC Ministry of Energy and Mines, PO Box 9320 Stn Prov Govt, Victoria, BC V8W 9N3, Canada, SIGLOCH, Karin, Earth Sciences Department, University of Oxford, South Parks Road, Oxford, OX13AN, United Kingdom, 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 and SHEPHARD, Grace, Centre for Earth Evolution and Dynamics, University of Oslo, PO Box 1048 Blindern, Oslo, 0316, Norway

We capitalize on two unique characteristics of massive vertical slabs that have been imaged beneath North America by high resolution mantle tomography: they mark the location of subduction zones that were stationary within a mantle reference frame, and they sink into the lower mantle at a fixed velocity of ~10mm/a. This permits us to constrain the position of subduction zones that deposited the vertical slabs since Early Jurassic times, and we utilize GPlates to reconstruct migration of ancestral North America (ANA) during Atlantic opening and collision with an east-pointing, 10,000 km-long, massive arc chevron (MAC). Highlights of this model include: (1) Intraoceanic subduction of ocean crust at the western edge of ANA beneath the intra-oceanic MAC until diachronous collision with ANA starting ~160 Ma. Collision caused drastic shallowing of the slab by ~130 Ma. (2) Formation of Alaska from train-wreck-style collapse of northern MAC, primarily after 80 Ma. Current slab inventories require Arctic Alaska >3000km west of ANA at ~160 Ma.

Our current iteration of the GPlates model can be downloaded from www.gov.bc.ca\GeoFile by same authors.

Session No. 65

T13. Tectonics of the Northwest Cordillera II: A Session in Honor of the Career Contributions of Ned Brown, Jim Monger, and Glenn Woodsworth
Sunday, 19 October 2014: 1:00 PM-5:00 PM
116/117 (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.175
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