Wilson Cycle Lecture Slides PDF
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Uploaded by GoldenLeif427
North Carolina State University
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Summary
These lecture slides cover the Wilson Cycle, a model explaining the cyclical opening and closing of ocean basins. The document describes the stages of the cycle, provides modern examples, identifies major ocean basins, and analyzes their characteristics. This would be useful for undergraduate-level geology courses.
Full Transcript
3-3 Wilson Cycle Describe the stages of the Wilson Cycle Provide modern examples for each stage Identify the 5 major ocean basins on a map Order the basins from largest to smallest based on areal coverage Recognize special characteristics of each basin ...
3-3 Wilson Cycle Describe the stages of the Wilson Cycle Provide modern examples for each stage Identify the 5 major ocean basins on a map Order the basins from largest to smallest based on areal coverage Recognize special characteristics of each basin Introduction John Tuzo Wilson Plate tectonics model Wilson Cycle refers to the sequence of events leading to the: – formation – growth/expansion – destruction/contracting – and eventual elimination of ocean basins. Embryonic Basin The cycle begins with the rifting of a large continent Crustal extension & uplift Rift valleys/normal faults Igneous activity associated with thinning of the lithosphere Juvenile Basin Cycle continues with subsidence & spreading without subduction Ocean crust development in rift High heat flows Narrow seas with parallel coasts & a central depression Mature Basin Spreading Little subduction Ocean basin with active mid-ocean ridge Palaeomagnetic stripes High heat flow Declining Basin Subduction associated with marginal trenches Ocean ridge not central e.g. East Pacific Rise Rates of spreading fast due to slab pull Terminal Basin Shrinking & uplift Young mountains Subduction associated with marginal trenches Suturing (Orogeny) Uplift Subduction ceases Thrust faulting Mountain belts One World Ocean Pacific Ocean Basin Largest basin (areal coverage 180,000,000 km2) Deepest (average depth 3,940 m) Extensive marginal seas and volcanic island systems and trenches Considerable mountain building and earthquake activity along boundaries Little freshwater input (not many major rivers drain into it) Atlantic Ocean Basin Second largest basin (areal coverage 107,000,000 km2) Average depth 3,310 m Large freshwater input (Amazon, Congo, Mississippi, Niger, Orinoco Rivers) Small number of marginal seas (Gulf of Mexico, Caribbean, Mediterranean) Indian Ocean Basin Basin areal coverage 74,000,000 km2 Average depth 3,840 m Large sediment input (Indus and Ganges River deltas) Small number of marginal seas (Arabian Sea, Persian Gulf, and Red Sea) Southern Ocean Basin Areal coverage 20,327,000 km2 Average depth 3,270m Bordered to the north by a continuous ring of water (latitude at 60° S) Coldest of all oceans (near freezing) Most biologically productive ocean (high nutrient concentrations) Extensive winter sea ice coverage Small number of marginal seas (Weddell and Ross Seas) Arctic Ocean Basin Smallest basin (areal coverage 14,056,000 km2) Average depth 1,038 m Centered on the north pole Shallow and land-locked Covered by sea ice Large sediment input from active glaciers
