Warm Up 12/3. Which of the following is NOT true about a batholith? a. It is considered a pluton. b. It may form the core of a mountain range. c. It is often a small part of a sill. d. It is the largest intrusive igneous body. What is true about all plutons? - PowerPoint PPT Presentation
Warm Up 12/3 Warm Up 12/3 1) Which of the following is NOT true about a batholith? a. It is considered a pluton. b. It may form the core of a mountain range. c. It is often a small part of a sill. d. It is the largest intrusive igneous body. 2) What is true about all plutons? a. They form near Earth’s surface. b. They form above Earth’s surface. c. They form below Earth’s surface. d. They cut across other rock layers. 3) Which of the following factors affects the melting point of rock? a. water content c. composition of the material b. confining pressure d. all of the above Answers: 1) c. 2) c. 3) d. Answers: 1) c. 2) c. 3) d.
Transcript
Warm Up 12/3Warm Up 12/31) Which of the following is NOT true about a batholith?
a. It is considered a pluton.b. It may form the core of a mountain range.c. It is often a small part of a sill.d. It is the largest intrusive igneous body.
2) What is true about all plutons?a. They form near Earth’s surface.b. They form above Earth’s surface.c. They form below Earth’s surface.d. They cut across other rock layers.
3) Which of the following factors affects the melting point of rock?a. water content c. composition of the materialb. confining pressure d. all of the above
Answers: 1) c. 2) c. 3) d.Answers: 1) c. 2) c. 3) d.
Plate Tectonics and Plate Tectonics and Igneous ActivityIgneous ActivityChapter 10, Section 3Chapter 10, Section 3
Location of Major VolcanoesLocation of Major Volcanoes
Convergent Plate BoundariesConvergent Plate Boundaries The basic connection between plate The basic connection between plate
tectonics and volcanism is that plate tectonics and volcanism is that plate motions provide the mechanisms by which motions provide the mechanisms by which mantle rocks melt to generate magmamantle rocks melt to generate magma
When an oceanic plate sinks under When an oceanic plate sinks under another plate, it brings water and rock another plate, it brings water and rock along with it. When that plate reaches a along with it. When that plate reaches a depth of ~100-150 km, and melting depth of ~100-150 km, and melting begins.begins.
The magma will then migrate to form The magma will then migrate to form either either volcanic island arcsvolcanic island arcs (Aleutians) or (Aleutians) or continental volcanic arcscontinental volcanic arcs (Andes and (Andes and Cascades)Cascades)
History of Cascade Range History of Cascade Range VolcanismVolcanism
Divergent Plate BoundariesDivergent Plate Boundaries Most magma is produced during Most magma is produced during seafloor seafloor
spreadingspreading (at the ocean ridges) (at the ocean ridges) As the plates move apart, rock from the As the plates move apart, rock from the
mantle rises to fill the gapmantle rises to fill the gap As this rock rises, the As this rock rises, the confining pressureconfining pressure
decreases, causing it to melt and form decreases, causing it to melt and form basaltic magmabasaltic magma
This basaltic magma is less dense than the This basaltic magma is less dense than the solid mantle rock, so it rises fastersolid mantle rock, so it rises faster
Most spreading ridges are located along the Most spreading ridges are located along the axis of an oceanic ridge (axis of an oceanic ridge (notnot the East African the East African Rift)Rift)
Intraplate Igneous ActivityIntraplate Igneous Activity Intraplate Volcanism –Intraplate Volcanism – occurs within a occurs within a
plate, not at a plate boundary (Hawaii and plate, not at a plate boundary (Hawaii and Yellowstone)Yellowstone)
Most Most intraplate volcanismintraplate volcanism occurs where a occurs where a mass of hotter than normal mantle material mass of hotter than normal mantle material called a called a mantle plumemantle plume rises toward the rises toward the surfacesurface
Most plumes are thought to begin at the Most plumes are thought to begin at the core-mantle boundarycore-mantle boundary
As the hotter mantle rock rises, it melts the As the hotter mantle rock rises, it melts the rock around it, causing magma to formrock around it, causing magma to form
It appears on the surface as a It appears on the surface as a hot spothot spot, and , and more than 40 of these have been identifiedmore than 40 of these have been identified
