OCE Chapter 3 Marine Provinces 01 20 2015 Bathymetry Determines ocean depths and ocean floor topography o Echo sounding and satellites are efficient in bathymetric tools o Most ocean floor features are generated First sounding HMS Challenger in 1870 s used a cannon ball on piano wire for soundings Route lasted 1 000 days Depth of water High or low pitch Bruce Heezen Marie Tharp Heinrich Berann Physiographic Maps of sea floor features Topographically accurate though hugely exaggerated Hotspot Only thing on earth that does not move Bathymetric features 1 Primary Features Continents and Ocean basins two main things you see when you look at the earth 2 Secondary Features 1 Continental margins a submarine canyons b slope rise shelf brook shelf c Submarine fans 2 Abyssal plain Sediment mud covered over volcanic rocks volcanic basement rock made of basalt a guyots table mounds b seamounts c abyssal hills o As you go away from the MOR the basalt seafloor gets older and the sedimentary wedge abyssal plain gets thicker 3 Mid Ocean Ridge 65 000km of MOR long linear chains a Fracture zones transform fault that offsets the rift valley b Rift valleys 1km deep fresh basalt is extruded new ocean crust is formed 4 Trenches Subduction Zones deepest places on earth 7 11km deep long 6 000km narrow 100km across mostly found in pacific Associated with very deep earth quakes Two kinds of trenches a Island arcs b Marginal Seas 1 Ocean plate Continental plate Peru Chile Active Margin 2 Ocean plate Ocean plate 1 plate is subducted Japan 3 Tertiary Features a b c Types of Continental Margins 1 Atlantic Margin Wide continental shelves high sediment supply Coastal plain is formed by sea level variation going up and down from the fall ling boundary between the piedmont and the upper coastal plain Coastal plain is an extension of the continental shelf they are separated by the beach Passive Margin few quakes Trailing edge margin Ex North Carolina 2 Pacific Margin Active Margin many quakes Leading edge margin Generally has a trench off shore Ex South America 3 Transform Margin Narrow shelves Types of Plate Boundaries 1 Convergent 2 Divergent iClicker Questions 1 Fracture zones 3 Tertiary Feature of Mid Ocean Ridge Island Arcs 3 Feature of Trench Sea Mounds 3 Feature of Abyssal Plane 2 Active Leading Pacific Edge Passive Atlantic Edge 3 Shelf Break feature of continental margin water depth is approx 3km 300m deep 4 Divergent Plate Boundary is Mid Ocean Ridge Convergent Plate Boundary is Trench Diatoms Oceanic photosynthetic primary producers Plants SUNLIGHT Autotrophs primary producers Herbivore zooplankton copepods secondary producers Sardine Tertiary Consumer Carbon Fixation C02 H20 CH2O O2 photosynthesis Chemosynthesis Uses reduced compounds oxygen to yield energy to drive carbon fixation CO2 CH2O o Takes place at Subduction zones MOR Hydrothermal Vents Bacteria Symbiosis Bacteria Chemotrophic chemical food Symbiosis Mutually beneficial OCE CHAPTER 4 01 20 2015 Marine Sediments Classification 1 Lithogenous Land 2 Biogenous Organisms 3 Hydrogenous Water 4 Cosmogenous Outer space Graw size Governs how far lithogenous sediments get off shore Coarse Larger particles Sand Gravel Closer to shore Fines Smaller Particles Farther from shore Settling velocity sinking rate of a particle is proportional to size Lithogenous Sediments Eroded rock fragments from land Terrigenous reflect composition of rock grain size from which derived Produced by weathering breaking up of rock Mainly mineral quartz SiO2 Clays Feldspars aluminum silicates Small particles eroded transported far from shore Carried to ocean streams wind glaciers gravity Greatest quantity around continental margins Gravel Grain size larger Coarse Sand Silt Clay Grain size smaller Fines Granite White rocks w black speckles o White rocks Quarts silica SiO2 o Black speckles Feldspars aluminum silicate minerals quartz feldspar make up granite Weathering happens by Freeze thaw Water erosion Plants Chipping Grain size Most important sediment property Proportional to energy of transportation and deposition Indicates environmental energy o High Energy Strong wave action Larger particles o Low Energy Smaller particles Larger Particles closer to shore ALSO effects mineral content Clays sands Sorting Measure of grain size uniformity Indicates selectivity of transportation process Neritic Near Shore o Shallow water deposits close to land Deposited quickly Pelagic Off Shore o Deep water deposits finer sediments Deposited slowly Abyssal red clays At least 70 clay sized particles from continents Red from oxidized iron Fe Abundant if other sediments absent Biogenous Sediment Hard remains of once living organisms Opal 2 major types o Macroscopic Visible to baked eye Shells bones teeth o Microscpic Tiny shells or tests Biogenic ooze Mainly algae protozoans Two most common chemical compounds Calcium Carbonate Silica Silica in Biogenous Sediments Diatoms photosynthetic algae Phytoplankton Radiolarians Protozoans use external food Zooplankton iClicker Questions Something that uses external food is a Heterotroph The opposite of an autotroph is Heterotroph A phototroph is a n Autotroph and Green Plants Silica sediments found ONLY under areas of high primary production by diatoms Calcium Carbonate in Biogenic Sediments Coccolithophores Nannoplankton Photosynthetic algae Coccoliths individual plates from dead organism Foraminifera Protozoans use external food calcareous ooze Distribution of Biogenous Sediments Depends on 3 processes o Productivity of organisms in surface water above ocean o Destruction Skeletal remains tests dissolve in seawater at floor depth Deep waters are corrosive to C2CO3 Below CCD calc carb Compensation depth Calcium Carbonate dissolves Hydrogenous Minerals precipitate directly from seawater o Manganese nodules Important Vocabulary Autotrophic Phototrophic Chemotrophic Heterotrophic Lithogenous Biogenous Biogenic Hydrogenous Authogenic formed in place Advection flow Neritic close to shore Pelagic offshore 2 Processes Control Grain Size Patterns 1 Deposition Large particles sink fast close to the shore small particles sink slow are carried further away from the shore 2 Erosion Wave energy erodes particles o Coarse sand on beach high energy o Mud Fine sand on beach low energy BIOGENOUS Large shelves CaCo3 Phytoplankton Offshore Diatoms Si shell opal Cocoliths CaCo3 shell Zooplankton Radiolarians Si shell opal THREE FORMULAS SiO2 Quartz SiO2 H2O Opal CaCo3
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