EESA06H3 Lecture Notes - Lecture 10: Euramerica, West Antarctic Rift, Central America
3 Mar 2012
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Document Summary
Canada"s geologic journey: the last 4 billion years: continents grow through time by obduction, north american continent shows 5 growth stages, arctica (2. 7 ga) oldest giganum (billion, columbia (1. 8 ga, rodinia (1. 0 ga) A + b +c = canadian shield (the craton) the old hard core rocks, rigid: pangea assembly (350 ma): maritime canada is added during appalachians orogeny (appalachian. Mountains) added sedimentary + highly fossil rocks: pangea breakup (<200 ma): british columbia is added during cordilleran orogeny (e. g. rockies) Brown old hard core ( ontario+ quebec area) Blue appalachian belt maritime canada. 2. 7 billion year old zircons uranium + lead dating. Age rings, amount of lead in the crystals. Detrital secondary, having be derived from. Tom crow expert on dating rocks something else. Zircons: from igneous rocks, weathered, zircons released, become sedimentary rock then metamorphosed into a gneiss. Continents grow thru time similar to swiss roll older stuff in the middle.
