GEOL 240Lg 1st Edition Lecture 3Outline of Last Lecture I. Transform boundariesII. San Andreas FaultIII. Mid-Oceanic FaultsIV. Transform FaultsV. Continental Lithosphere, Oceanic Lithosphere, Continent- Continent CollisionOutline Current Lecture I. Sea Floor Spreading Drawing w/ explanationII. Rifting of a ContinentIII. What is Decompression melting?IV. East African RiftV. Mount KilimanjaroVI. AulacogensVII. Diagram of the Subduction ZoneVIII. Convergent Plate BoundariesIX. Volcanoes Current Lecture- The illustration below is an example of the Sea Floor Spreading. - It shows how Rifting and Seafloor spreading at the crest- Rifting and seafloor spreading in Iceland- Rifting of a continent and seafloor spreading to form a new basin- This is called Decompression Melting - When rift the lithosphere over rising magma plums, the release in pressure causes decompression- East African Rift Red Sea… a lot of fault systems that are dropping of valleys- Sometimes rift start to form into an ocean but not all the rifts get to form into oceans. - Mount Kilimanjaro this is the tallest peak in the continent of Africa. - This Mt. is composed of 3 distinct volcanic cones. Kibo( 5,895 m), Mawenzi (5,149m), and Shira (3,962m)Aulocagens-> Mississippi River Broke North America In simple terms, aulocagens are failed rift arms. Another example of this is the Nigerian River Rift- Pacific Ring of Fire This is just an area where a large number of earthquakes and volcanic activity occur. There are many eruptions in the Pacific Ocean. This explains why we have so many earthquakes in California due to the Pacific Ocean ring of fire.- The picture above is the Subduction Zone.- It explains how deep the oceanic lithosphere is and the trenches in the ocean/- H2o also causes in minerals to be driven off.- 100km deep melting above slab occurs in 100km and then it goes straight downConvergent Plate Boundaries- Lava = andesite- (high-visual) (thick)- Also, there are a lot of gas carbon monoxide - Gas bubbles5km down 100 meter bubbleVolcanoes kills people because the pressure is getting lower so it comes out and it stays there because of the pressure contrast. Then, you guessed it… it
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