GeologyMidterm1StudyGuide.pdf GEOL 1313 - 002
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This 10 page Study Guide was uploaded by Diana Hernandez Vega on Monday September 28, 2015. The Study Guide belongs to GEOL 1313 - 002 at University of Texas at El Paso taught by Tina L. Carrick in Summer 2015. Since its upload, it has received 61 views. For similar materials see Intro to Physical Geology in Science at University of Texas at El Paso.
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Date Created: 09/28/15
Geology Midterm 1 Study Guide Chapter 2 Plate Tectonics Introduction 0 Accepted in the 1960 s 0 There are 3 types of boundaries 1 Divergent move away from each other 6 9 I New ocean oor created I Located along the crests of oceanic ridges I Oceanic ridges and sea oor spreading sea oor elevated oceanic ridges o Rift valley Along the crest of the ridge is a canyonlike feature 0 Sea oor spreading the mechanism that operates along the ridge to create IICW ocean OOI I Continental rift an elongated depression will develop within the region of the divergence 2 Convergent move towards each other 9 6 I Subduction zones the leading edge of one plate is bent downward as it slides beneath the other I Deepocean trenches the surface manifestations produced at subduction ZOIICS I Oceanic continental convergence oceanic slab sinks beneath the continental block into the asthenosphere 0 Partial melting water from the subducting plate mixes with the hot rocks of the asthenosphere generating magma 0 Continental volcanic arc Sulting volcanic mountain chain 39 Oceanicoceanic convergence two oceanic slabs converge one descends beneath the other 0 Partial melting initiates volcanic activity 0 Volcanic island arc volcanoes emerge as islands 39 ContinentalContinental convergence Continued subduction can bring two continents together 3 Transform slide past each other side by side Tl I fracture zones join two segments of an oceanic ridge system along breaks in the oceanic crust Background 0 Alfred Wegener wrote Pangea all land in 1915 0 He portrayed the break up and the position they are in Evidence 0 Continental Jigsaw Puzzle 0 Fossils same fossils in different continents 0 Rock types and geological features 0 Ancient climates Plate Tectonics o Lithosphere earth s strong outer layer 200 km 0 lithospheric plates The lithosphere is broken into approximately two dozen smaller sections always in constant motion 0 Asthenosphere hotter weaker region of the mantle under the lithosphere Testing the Plates Tectonic Model 0 Mantle plume cylindrically shaped upwelling of hot rock 0 Hot spot surface expression of a mantle plume 0 Hotspot track chain of volcanoes 0 Convective ow in the mantle is what drives the force of plate tectonics o Convection warm buoyant rocks rise and cool dense rocks sink 0 Slabpull fore subduction of a cold oceanic lithosphere o Ridgeforce elevated lithosphere on an oceanic ridge will slide down due to gravity 0 Paleomagnetism magnetite found is basaltic rocks frozen in position and indicates the position of the north pole at the time of the rock solidification 0 Magnetic Reversal earth s magnetic eld periodically reverses polarity 0 Normal Polarity rocks that have the same magnetism as the present magnetic field 0 Reverse Polarity rocks that have opposite magnetism as the present magnetic field 0 Magnetic Time Scale shows sequence of shifts in the polarity of Earth s magnetic eld determined as lava ows Chapter 12 Earth s Interior Internal Structure 0 Made of three main layers 1 Crust 39 Continental 0 heterogeneous o 40 km thick 0 27 gcmquot3 of density 39 Oceanic 0 7 km thick 0 Made of basalt and gabbro 0 30 gcmquot3 of density I Moho boundary between the crust and the mantle 2 Mantle I 82 of Earth s volume 39 Solid rock layer 0 Upper mantle 660 km deep 0 Contains lithosphere and asthenosphere 0 Transition zone lowest portion of mantle 410660 km 0 Lower mantle from transition zone to liquid core 2900 km 0 D layer boundary between rocky lower mantle and liquid outer COI39C 3 Core I 16 of earth s volume 39 Outer core liquid 0 absence of S waves I Inner core solid dense sphere 0 Density of 13 gcmquot3 0 Mineral Phase Change minerals are compressed under higher pressures 0 Seeing Seismic Waves re ect and refract as they pass through Earth s layers 0 Seismic Velocities P compressional and S shear Earth s Temperature 0 Core 5500 degrees C 0 Surface 0 degrees C 0 Heat travels by conduction convection and radiation 0 Convection transfer of heat Where hot minerals replace cold minerals outer core 0 Viscosity material s resistance to ow 0 Conduction transfer of heat through material inner core 0 Geothermal Gradient the pro le of Earth s temperature at each depth Earth s 3D Structure 0 Changes at the surface are due to gravity 0 Seismic tomography collecting data at many different seismic stations to see parts of the Earth 5 interior 0 Earth s magnetic eld is produced by convection of liquid iron in the outer core 0 Geodynamo magnetic field caused by spiraling columns of rising uid in the outer core Chapter 10 Crustal Deformation o Deformation all changes in the shape or position of a rock body in response to stress 0 Elastic rock returns to nearly its original shape and size When stress is removed 0 Ductile once elastic limit of a rock is surpassed it bends o m once elastic limit of a rock is surpassed it breaks 0 Rock or Geologic Structures features that result from forces generated by the interactions of tectonic plates 0 m the force that causes a rock to deform folding fracturing or faulting o Compressional squeezes a rock and shortens a rocks body o Tensional pulls apart rock and lengthens is o m makes a motion similar to slippage 0 Lain a change in shape of a rock caused by stress 0 Factors that affect rock strength 0 Temperature higher temp ductile cooler temp brittle o Confining pressure squeezes rock making it stronger and harder to break 0 Rock type 0 Time force applied for a long time result in ductile 0 m cracks in the rocks resulting from the rock being stretched and pulled apart 0 Fths fractures in the rocks Where rocks on one side of the fault are displaced relative to the rocks on the other side of the fault Folds formed by ductile deformation 0 Folds wave like undulations formed in rocks o Anticlines up folded or arched sedimentary layers 0 Synclines down folded or troughs of rocks 0 M upward circular features football stadium 0 BLins down warped circular features upside down cereal bowl 0 Monoclines large step like folds otherwise sedimentary strata Faults and joints formed by brittle deformation 0 Faults fractures in rocks along which displacement has occurred 0 Dipslip faults occur when movement is parallel to the inclination 0 Hanging wall rock surface above the fault o Footwall rock surface below the fault 0 Normal faults hanging wall moving down relatively to the footwall o Faultblock mountains larger scale normal faults are associated with I Horsts uplifted blocks I Grabens downdropped blocks I Half grabens tilted fault block I Detachment faults boundary between ductile and brittle rock units 0 Reverse faults hanging wall moving up relatively to the footwall o Thrust faults less than 45 degrees overlaying plate moves almost horizontally 0 Strikeslip faults placement that is horizontal and parallel to the strike of the fault o Transform faults large strike faults that cut through the crust to accommodate plate motion 0 Rightlateral As you face the fault the opposite side of the fault moves to the right o Leftlateral As you face the fault the opposite side of the fault moves to the left 0 Fault scraps vertical displacement along the fault produces long and low cliffs 0 Obliqueslip faults exhibit both a strikeslip and a dipslip movement 0 Joints fractures in a rock where there has been no rock movement Chapter 11 Earthquakes o Earthquake ground shaking caused by the sudden and rapid movement of one block of rock sliding past each other 0 FocusHypocenter rock slippage that originates in the ground 0 Seismic waves stored up energy that radiates in all directions from the focus 0 Epicenter point on the ground surface directly above the focus 0 Elastic rebound process when deformed rocks snap back to their original position 0 Aftershock numerous small earthquakes that usually follow after a major earthquake o Foreshock minor earthquakes that sometimes precede a major earthquake by days weeks or months Faults and Earthquakes 0 Reverse and thrust o Megathrust fault boundary between the sub ducting and overlaying plate in a subduction zone 0 Fault creep slow gradual displacement Seismology 0 Seismology the study of earthquake waves 0 Seismographs instrument that records movement of Earth in relation to a stationary mass on a rotating drum or magnetic tape 0 Records obtained are called seismograms 39 Seismic waves travel in rock layers below the Earth s surface 0 Primary waves P compression waves travel through anything 0 Secondary waves S shear eaves travel only through solid 0 Surface waves 1 causes to move the ground up and down 2 causes to move the ground side to side Determining the Size of Earthquakes 0 Intensity a measure of the degree of earthquake shaking at a given locale based on the amount of damage 0 Modified Mercalli Intensity Scale developed using California buildings based on property destruction 0 Magnitude an estimate of the amount of energy released at the source of the earthquake o Richter Scale calculated by measuring the amplitude of the largest seismic wave recorded on a seismogram o Moment Magnitude measures total energy released during the earthquake Destruction 0 Liquefaction process where loosely packed waterlogged sediments behave as uids during intense shaking of an earthquake 0 Tsunami series of large waves NOT A TIDAL WAVE Can Earthquakes be Predicted 0 Seismic gaps tectonically quiet zones along a fault Where strain is currently building up 0 Paleoseismology is the study of prehistoric earthquakes
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