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This 13 page Reader was uploaded by Olivia Tenery on Friday April 25, 2014. The Reader belongs to a course at University of Oregon taught by a professor in Fall. Since its upload, it has received 95 views.
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Date Created: 04/25/14
GEOL 307 lecture 5 42514 650 PM Video on evolution Bathymetry and how we measure it Measures the vertical distance from the ocean surface to mountains valleys plains and other sea floor features Measuring Bathymetry o Soundings Poseidonus first sounding 85 BC Line with heavy weight Sounding lines used for 2000 years To calculate the length they had a crew member stretch out his arms to count the number of lines they looped it 9 unit of measure is a fathom 2 18 meters or about 6 ft first systematic measurements HMS Challenger 1872 0 Echo Sounds Echo sounder or fathometer Reflection of sound signals They start a clock when they start the ping and wait until they get a ping back and hear an echo The speed of sound in water is faster than the speed of sound in air because water has a higher viscosity than air 2 Air is very compressible compared to water German ship Meteor identified mid Atantic ridge in 1925 Lacks detail may provide inaccurate view of the sea floor 0 Precision Depth Recorder PDR 1950s focused high frequency sound beam first reliable sea floor maps produced helped confirm seafloor spreading 0 Modern Acoustic Instruments 0 Side scan sonar Towed behind the ship to provide very detailed bathymetric strip map Muti beam echo sounder 0 Seismic reflection profiles Air guns Strong low frequency sounds Details ocean structure beneath sea floor Transmitted sound through rock is even more efficient than sound through water which is better than through air 2 Earthquakes travel very quickly 0 Sea floor mapping from Space Uses satellite measurements Measures the sea floor features based on gravitational bulges in sea surface When there is excess mass the water piles up in groups like over the mid Atlantic ridge 2 If there was no gravitational attraction it would be smooth Indirectly reveals bathymetry Uses radar pulses from space seafoor Hypsographic curve 0 Shows relationship between height of land and depth of ocean o Uneven distribution of areas of different depthselevations 0 Elevation how high a mountain is how high score is on test 0 Percentage of earths surface that is at that elevation how many students got that specific score Avg ocean depth 3729 meters 0 Avg land eevation 840 meters 0 Ocean Provinces Three Major provinces Continental shelf flat zone from shore to shelf break 0 Shelf break is where marked increase in slope angle occurs Continental slope where deep ocean basins begin 0 Submarine canyons like grand canyon but underwater Carved by turbidity currents o Topography similar to land mountain ranges Continental rise transition between continental and oceanic crust o Marked by turbidite deposits from turbidity currents o Graded bedding in turbidite deposits 0 Deposits generate deep sea fans 1 Continental Margins Shallow water areas close to shore 0 Passive East coast is a passive margin No major tectonic activity Not close to any plate boundary Continental shelf wider break slope rise no trench 0 Active Convergent or transform plate boundaries Much tectonic activity Transform Continental Margin 2 Less common 2 Linear islands banks and deep basins closer to shore 2 Ex Coastal cali san andreas fault 2 Deepocean basins O Deep water areas farther from land 3 Midocean ridge 0 O OOOO submarine mountain range longest mountain chain basak wholly volcanic central rift valley downdropped by seafloor spreading fissures and faults in rift valley seamounts ta volcanoes pillow lava or pillow basalt shapes formed when hot basaltic lava quickly cools Hydrothermal vents sea floor hot springs let unusual deep ocean ecosystems survive without sunlight produces het and minerals Abyssal Plains extend from base of continental rise deepest flattest parts of the earth suspension settling of very fine particles sediments cover ocean crust irregularities We deveoped in Atlantic and Indian Oceans Ocean Trenches and Volcanic Arcs Convergent margins generate ocean trenches o Deepest parts of oceans Ring of Fire Margins of the pacific ocean Majority of worlds active volcanoes and earthquakes Marked by convergent boundaries When Pangaea formed Africa collided with N America and that is what gave us the Appalachian mountains Oceanic Islands Volcanic activity come from hotspots GEOL 307 42514 650 PM All drains lead to the ocean Chapter 4 Marine Sediments Transportation Methods Water rivers streams oceans Air sand wind dispersion Ice glaciers Gravity landslides rock slides slumping 0 Moving material from high to low 0 Transporting it without breaking it Worldwide Marine Sediment Thickness map on PowerPoint Gulf of Mexico major supply river us the Mississippi Nile Nile Columbia blue is almost no sediment red is really thick Ocean currents affect this Sediment Types Lithogenous Derived from land 0 Rock fragments quartz sand silt clay volcanic ash Eroded rock fragments Also called terrigenous Produced by weathering Breaking of rocks into smaller pieces Carried by all different transportation methods Finer sediments farther from shore No biological fragments Grain size Proportional to the energy of transportation and deposition OOOO OOO Biogenous Derived from organisms 0 Biological origin hard remains of a once living organism 0 Calcium carbonate CaCO3 Algae protozoans shellscoral reefs Coccoithophores i SiO2 Diatoms agae radiolarians protozoans chert silica ooze made up of dead microscopic organisms Diatoms are photosynthetic algae autotroph Radiolarians are protozoans use external food heterotroph Silicious ooze O O O O 2 Also called nanoplankton 2 Photosynthetic algae 2 Cocciths individual plates from dead organism 2 Rock chalk Foraminifera 2 Microscopic protozoans that form calcareous ooze Netric Deposits 2 Dominated by lithogenous sediment may contain biogenous sediment 2 Carbonate deposits Marine carbonates primarily limestone Stromatolites 2 Fine layers of carbonate 2 Warm shallow ocean Calcareous Ooze and the CCD 2 Below a certain depth CaCO3 cannot be in a solid form it dissolves warm water dissolves salt 2 CCDCacite compensation depth The CCD varies with temperature Macroscopic and Microscopic o Macroscopic O Visible to naked eye Shells bones teeth Microscopic Tiny shells or tests biogenic ooze Mainly algae and protozoans Hydrogenous Derived from water OOOO Precipitation of dissolved materials directly from seawater due to chemical reactions Manganese nodules Fist sized lumps of manganese iron and other metals Very slow accumulation Many commercial uses Unsure why they are not buried by seafloor sediments Phosphates and Carbonates Oolites Metal Sulfides Evaportes Minerals that form when seawater evaporates Cosmogenous Derived from outer space 0 O 0 Space dust meteors Tektites space dust silica gas All are spherical when it comes into the atmosphere edges are burnt off Paleoceanography and Marine Sediments Study of how ocean atmosphere and land interactions have produced changes in ocean chemistry and circulation biology and climate Sediment Transport and Depositional Environments Sediment Distribution Netric O OOOO Shallow water Close to shore Dominantly lithogenous Just off the continental shelf Deposited quickly Pelagic O 0 Fine grained materials Abyssal clays 0 Far from shore trenches o Deposited slowly Resources from Marine Sediments Energy Resources 0 Petroleum from continental shelves 0 Gas hydrates very abundant submarine landslides can release large volumes of gas hydrates that can sink ships BERMUDA TRIANGLE Sand and Gravel tingod Evaporite salts sea water evaporates this is where we get our table salt from Phosphorte Manganese nodules and crusts GEOL 307 42514 650 PM Water Seawater and Salinity Water has many unique thermal and dissolving properties Seawater is mostly water molecules but has dissolved substances The ocean is layered by salinity and density differences Atomic Structure Basics Atoms are the building blocks of all matter Subatomic particles protons neutrons electrons o Protons and neutrons make up the nucleus o There are the same amount of electrons in the outer shell that there are protons and neutrons in the nucleus Number of protons distinguished chemical elements Water molecule 9 held together by covalent bonds Strong covalent bonds between one 0 atom and 2 H atoms Hydrogen bonding Weak bonds between molecules Weaker than covalent bonds but still strong enough to result in High water surface tension 0 High solubility of chemical compounds in water 0 Unusual thermal properties of water 0 Unusual density of water 0 Water as the Universal Solvent It sticks to other polar molecules Electrostatic attraction produces ionic bond Water can dissolve almost anything Thermal properties of water Three states of matter 0 Heat Energy of moving molecules Temp is a measurement of avg kinetic energy Calorie is the amount of heat needed to raise the temp of 1 gram of water by 1 degree Celsius Van der Waals forces weak attraction that becomes much stronger as molecules get very close to eachother Water39s Heat Capacity and Specific Heat 2 Heat capacity amount of heat required to raise the temp of 1 gram of any substance by 1 degree C 2 Specific Heat heat capacity per unit mass 2 Latent Heat it doesn39t change temperature as we put more energy into it it is changing phase To vaporize the water temperature does not have to be 100 degrees the atoms just need to have enough energy to vaporize an average between high energy and some sunHght The ocean is the temperature stabilizing Thermostatic Mechanism for planet earth It moderates the temperature on earths surface buffering effect 0 Equatorial oceans do not boil 0 Polar oceans do not freeze solid Marine effect 0 Oceans temp changes from day to night and during different seasons Continental effect 0 Land temps change from day to night and during different seasons Water density and Temperature Density of water increases as temperature decreases 9 thermal contraction Ice is less dense than water Increasing pressure ice skating reduces the freezing temperature of water Dissolved solids like seawater also reduce the freezing temperature of water Salinity How many ppt of dissolved substances are in 1000 parts of water Surface salinity variation by latitude o Thermocline the temperature goes down with depth Thermocline is at low latitudes o Halocline Separates ocean layers of different salinity at low latitudes salinity decreases with depth at high latitudes salinity increases with depth PycnocHne o Abrupt change of density with depth Determining Salinity o Evaporation 0 Chemical analysis titration 0 Electrical conductivity Salinometerconductivity meter Processes affecting Salinity Decreasing salinity 0 Adding freshwater to the ocean o Melting sea ice 0 Precipitation Increasing Salinity o Removing water from ocean 0 Sea ice formation 0 Evaporation Processes that addsubtract dissolved substances to the water Volcanoes River discharge Precipitation Hydrothermal activity at the mid ocean ridge GEOL 307 42514 650 PM Hw 5 paleoseismology 8 the day and night temp differences between continents and oceans Extra Credit Chapter crossword puzzles due review session for final Water has a high heat capacity This is helpful to the oceans because it absorbs and distributes heat You can put a lot of energy into water without changing its energy or its phase It gets less dense when it heats up and more dense when it cools clojwn ice will float in water 0 If it kept sinking then the entire ocean would become filled with ice Hydrogen Bonding The polarity of the water molecule also gives it the property of being the Universal Solvent 0 It will grab something that will make it electrically neutral The ocean is layered by salinity temperature and density depending on the latitude Halocline separates ocean layers of different salinity There is no thermocline in high latitudes abrupt change of temperature with depth Abrupt change of density with depth pycnocline Volcanic eruptions will raise salinity ppt Acidity and Alkalinity Acid releases a H ion when dissolved in water Alkaline base releases a hydroxide ion OH in water pH scale measures hydrogen ion concentration 0 low pH Acid 0 high pH akaine base 0 pH 7 neutral Carbonate Buffering scale ocean pH averages 81 but has a range from 8083 buffering keeps the ocean from being too acidic or too basic 0 our stomachs are almost as acidic as battery acid but it doesn39t burn our organs because of the buffer lining that we make that helps neutralize the pH of the stomach oceans can absorb CO2 from the atmosphere without much change in pH Desalinization removing salt from seawater Distillation most common processwater is boiled and condensed Electrolysis eectrode containing freshwater Reverse Osmosis salt forced through membrane into fresh water Freeze Separation water frozen and thawed multiple times
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