Unformatted text preview: SeaFloor Features: mid ocean ridge:oceanic platesvery dense...made of basalt(MAFIC) passive magma not a straight line has lots of fracture zones has to curve boundary plates rock fractures creates transform plate boundaries(sliding) less seismic activity perpendicular to faults island arc(plate boundariesconvergent→ formed from the orientation of the plates) vs island chain island arc: as subduction: melting point of rock changes(organic substances)> lower liquefying rock and gases→ make the island arc volcano magma gases organics lots of oxygen lots of different chem compositions result:violent eruptions→ composite randomized eruption patterns not as pure/deep magma intermediate to felsic rhyolitic/andesitic seen when subduction done and creates a trench island chain: floating on magma rock and magma is like ice and water when magma sporadic, not continuous hotspot doesn't move pattern to eruption no predicted time period can tell which is oldest and which is youngest more mafic Abyssal plainbig plain at bottom of ocean Abyssal Hilldeep ocean bumps… Continental(all are submerged to): shelf: flat...very low gradient..long→ beach slope:steep drop off with a lot higher gradient rise: low gradient more northsmaller shelf? more westsmall slope and rise(active)..long shelf Guyot Active volcano composite usually convergent steep slope carbonates are deposited in the CCD(carbonate compensation depthcement) are taken and used by animals lots of CO2 that make up shells tests,corals collect along edge of mountain coral grows vertically & secreting solid carbonate as volcano moves away or no more magmaATOLL eventually mountain top disappears flat on top white island with blue on inside keeps erodingGUYOT: below compensation depth, below saturated area so now it dissolves since no more carbonates coral reef doesnt have saturated surface dies out why? where lat we find these organics(use biologic indicatorswhere it was when it formed since earth is dynamic) how much is dissolved at a depth where a geological structure was energy of wave at surface dissipates at a certain depth(wave base:half the wave length) celerity why waste energy if u can figure out how deep to travel and under this depth, its not fighting the water(glider) gets compressed, topple and collapse where wave base is deeper than bottom of ocean Hotspots: anywhere on the earth start in triplicates one fails africa rift valley Trench: convergent boundaries trenches do with island arc volcanos Suspect Terrain: sheared off subduction area Gas stuff Continental rise, slope cold icy jail cell ...
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- Fall '15
- Trench, Island arc, Africa Rift Valley, White Island, triplicates