GENERAL GEOLOGY (OROGENY & MOUNTAIN BELTS) Flashcards
Young Mountain Belts in the World
NA Cordillera (Capehorn - Alaska)
Andes
Alpine-Himalaya
Atlas
Alps
Caucasus
Zagros
Tien shan
Himalayas
West Pacific Mountaunous Terrain
What is the meaning of Cordillera
“Spine” or Back bone
Age of Himalayas
50 Ma
Old Moutain Belts
Appalachians (E. US)
Urals (Russia)
Caledonian Sz
Altay Sayan China
Great Dividing Ranges (aus)
Processes that collectively produce mountain belt
Orogenesis “Oros” Mountains
Type of subduction for Island Arc type orogey
Ocean-Ocean
Andean Type
Continental-Ocean
Continental Margins where sedimentation has produced a thick platform of shallow water sandsones, limestones and shales
it will be peeled or cut off from the descending plate and thrust (Accrete to the adjacent continental blocl)
Depth of partial melting by devolatilization and inducing of fluid at subduction zones
100 kilometers
Partial melting of Ultramafic Rocks produces this kinds of Magma
Primary Magma (Basaltic)
After primary melting what happens next?
Basaltic magma which is less denser will rise and will pond below continental crust
Then afterwards?
Through magmatic differention, a basltic magma can generate low density felsic or intermediate secondary magma which can rise through the continental crust
In continental-oceanic volcanic arcs what proceeds after subduction?
Uplift
Why does continental crust impedes the ascent of molten rock?
Because of its density and great thickness
When a magma intrudes the crust and crystallizes at depth it forms
Batholiths
Resulting chaotic accumulation of deformed and thurst faulted sediments and scraps of ocean crust
Accretionary wedge
Since the accretionary wedge acts as a barrier for sediments from the Volcanic Arc to the trench, it forms an accumulation of sediments in between the accretionary wedge and the volcanic arc which is realatively undeformed
Forearc Basins
Proto Pacific Plate
Farallon Plate
Example of A volcanic Arc system
Sierra Nevada - Volcanic Arc
Great Valley - Forearc Basin
Coast Ranges -Accreationary Wedge
Terrain vs Terrane
Terrane (E for evolved)- A crustal fragment with distinct and recognizable series of rock formations transported by Plate Tectonics Processes
Terrain - Shape of the surface topography or lay of land
A type of orogeny associated with Pacific like oceans in which Fast spreading rates is balanced by the high rate of subduction which make it unlikely to close but rather carry islands arcs or crustal fragments to collide with an active citinental margin through collission and orogeny
Cordilleran type Mountain building
Nature of terranes in the pacific
Microcontinents
Island Arc
Submerged Plateau
When the oceanic plate contains small seamounts (submerged) and meets and andean type subduction, what will most likely happen?
Submerged plateau will be consumed through the descending oceanic slab unless they are thick units or are mainly composed of light felsic minerals
When a crustal fragment accretes to the adjacent continental crust what would most likely happen?
It will be peeled or cut off from the descending plate and thrust (Accrete to the adjacent continental blocl)