Take Home Final Exam Questions Geology 1207.1 2016 A large part of southern Nova
ID: 297978 • Letter: T
Question
Take Home Final Exam Questions Geology 1207.1 2016
A large part of southern Nova Scotia is made up of granites (South Mountain Batholith) (375-380 million years old) exposed at surface. What plate tectonic and geological conditions were necessary to produce this large volume of granite? How could these rocks become exposed at surface? Why is the South Mountain Batholith considered to be a “Specialized Granite”? How did the Granite uranium vein type deposits form? What genetic relationship would the uranium occurrences in the granite have with the younger “uranium roll front deposits” in the Horton Group (Carboniferous, 355 million years old) sedimentary rocks? (Give references to support your answer). Value 33.33%.
Explanation / Answer
The batholiths and similar igneous structures are a result of cooling and crystallization of the magma melt deep under the crust.The magma melt can be generated by the partial melting of the zone as a result of subducting plates.The magma melt can also be generated by heating of the crust by hotspots.The hotpots are thought to be fixed heat sources,deriving their heat from the core.The crustal rocks undergo partial melting,when the plate rides over a hotspot.The magma generated may rise as magmatic diapirs in the crust and could get cooled and solified 5-30Km underground as plutons.Batholiths are formed when many plutons converge to form a huge expanse of granitic rock.
Uranium is an incompatible element and will hence tend to accumulate in highly fractionated and evolved granitic melts,frequently appearing in quartz veins in the granites.
These granitic melts containing uranium ores like pitchblende intrude through granitic bodies fractures,shear zones and stock works to form Uranium vein depositions.
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