4 Geology of Cordillera Flashcards
What is the elemental makeup of the earth? (5)
Iron (32.1%), Oxygen (30.1%), Silicon (15.1%), Magnesium (13.9%), and other (8.8%)
What layer of the earth that flows?
Asthenospheric mantle
What are the two types of lithosphere? And what is the thickness and density?
continental, granitic crust, ~150 km, less dense
Oceanic, basalt crust, ~7-100 km, more dense
What are the three ways heat flows from the earth?
Conduction: Moving from hot to cold
Convention: Magma moving to the surface (slide 13)
Advection: From a volcano
What is the force driving plate movement?
Convection traction
See slide 16-19 shows different kinds of subduction
What is the Ring of Fire?
Refers to active volcanos on the pacific plate
Where is the Intermontane belt?
West of the omenica belt
What are kind of rocks types are in the intermontane belt?
Mostly volcanic and sedimentry rocks, and is very complex
What are the physiographic regions in the intermontane belt? (4)
Yukon Plateaus, Stikine Plateaus, Skeena Mountains, and Interior plateaus
What is the metamorphic grade in the intermontane belt?
Mostly low grade metamorphism
What is the origin of the intermontane belt?
Exotic terranes
What kind of metamorphism occurs in the intermontane belt?
Accetionary prism (Med. pressure, med. temp.)
Collisional mountain belt (High pressure, low temp)
Define exotic terranes?
A tectonostratigraphic terrane is a fragment of
continental or oceanic crust formed on, or broken off
from, one tectonic plate and accreted (sutured) to the
crust lying on another plate. The crustal fragment
preserves its own distinctive geologic history, which is
different from that of the surrounding areas
What did the intermontane belt start out as?
Volcanic islands (island arc)
How many terranes are within the intermontane superterrane?
6
What important mountain is within the coast belt?
Mount Logan is in this range
What are the physiographic regions in the coast belt? (2)
St. Elias Mountains, and Coast Mountains
What is the main rock type in the coast belt?
Mainly jurassic to cenozoic granitic rock (80%)
What’s the metamorphic grade in the coast belt?
Granite mostly, there’s also contact metamorphism
What is the coast belt’s structural style?
Complex
What is the Stawamus Chief?
The great cleft in the mountain’s cliff face in the Squamish area
What is the physiographic regions are in the insular belt? (2)
St. Elias Mountains, and the insular mountains
Mount Logan straddles this and the coast belt
What rock types are in the insular belt?
Terrane rock (mostly Wrangellia) volcanic, some plutonic, and sedimentary
sedimentary rocks
