| Index | Block 1 | Block 2 | Block 3 | Block 4| SXR260 | S193 | Home |
S260 Geology Block Three - Internal Processes
Block three has been easier than block two, but there is still a lot to take in and new concepts to learn and understand. The course is slowly coming together as various geological principles are revisited and becoming clearer. I'm really looking forward to the summer school where I will be able to see features for real, and hopefully continue to improve my understanding of geology.
Introduction to block three
Block three considers the Earth's internal processes - mainly those that relate to geology and occur at a shallow depth, in the Earth's crust, or upper layer of the mantle.
Top
The Earth
The Earth is layered by composition (determined seismically) into a solid inner core, a liquid outer core, a peridotite lower mantle, and an upper mantle. This is then covered with either an oceanic or continental crust.
Plate tectonics - the Earth is coverd in a series of plates whose size and position change over time. Geological activity such as volcanoes, earth quakes and mountain building occur at the plate boundaries.
heat escaping from the Earth's interior is generated by the decay of radioactive isotopes.
Top
Igneous rocks and the rock cycle
Melting rocks
Silicate rocks made up of more than one mineral melt over a range of temperatures and pressures. A P-T phase diagram shows zones of liquidus and solidus states of the rock. In hydrous (or any volatile) conditions, liquidus and solidus plot at lower temperatures for a given pressure.
Top
Intrusive rocks
Plutons - coarse grained, lack chilled margins
Minor intrusions - little or no metamorpic aureole
Top
Volcanic rocks
Underwater lava eruptions (pillow lava)
Pyroclastic eruptions (explosive)
Top
igneous provinces
Constructive plate boundaries
Hot spots
Flood Basalts
Destructive plate boundaries
Continental collision
Top
Metamorphism
Dynamic metamorphism - occurs in areas of intense local deformation such as fault zones or shear zones.
Contact metamorphism - caused when igneous intrusions come in contact with country rock and cause heat to be dissipated.
Regional metamorphism - large scale metamorphism associated with continental collision or subduction (deformation).
Top
Rock structures
Brittle deformation and joints
Faults
Shear zones and ductile deformation
Folds
Cleavage and Schistosity
Top
Rock deforming processes
Stress and strain in rocks
Top
How structures form
Competent lithologies break more easily than incomptetent lithologies.
Brittle failure occurs at the surface.
Top
Tectonic environments
Block three exam revision
• Read through block 3 section summaries and objectives.
• Browse Frances' S260 revision site.
• Browse Digital kit and digital microscope cdroms.
• Get familiar with block three bookmark (allowed in exam)
Top
| Index | Block 1 | Block 2 | Block 3 | Block 4| SXR260 | S193 | Home |
URL of this page:[ http://www.larnach.info/S260/three.htm ]
Block three links
Global Volcanism Program
Igneous rocks in cross section
Books
