EESB15H3 Lecture Notes - Lecture 20: Antler Orogeny, Island Arc, Orogeny
11 Dec 2017
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Document Summary
Great rift valleys fracture pangea (200 ma). Evaporites forming in the incipient (beginning) rift. Figure 1: building the west coast - the western cordillera. Involves the accretion of over 50 individual terranes. Seamounts, coral reefs, microplates, accretionary complexes, island arcs etc. Some formed close to laurentia (peri-laurentian) immediately prior to amalgamation. Like the appalachians, there are multiple pulses of orogenesis as different terranes and arcs accreted: Island arc collision, reversal of subduction zone polarity. Figure 3: jurassic orogenesis - southern cordilleran, nevadan and sevier orogeny. Creation of a chain of plutons below a terrane (sierra nevada mountains) and subsequent accretion to north america to cause the sevier deformation. There was extensive plutonism below a superterrane. Batholith: a very large igneous intrusion extending deep in the earth"s crust. There"s evidence of the sevier orogeny in the form of a fold-thrust belt deformation. Resulted in the beginning of the western interior seaway. Foreland basin formation as a result of the collisional orogeny.
