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4. Ocean Basin Shape: Contraction and Isostasy
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4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Apr 22, 2020

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Page 1: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

4. Ocean Basin Shape: Contraction and Isostasy

Page 2: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Evolution of Thermal Structure in Cooling Rock Column

Page 3: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Contraction of Cooled Lithosphere – Density Increase

The equation for volumetric change can be converted to an equation for density contrast.

Page 4: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Cooling Oceanic Lithosphere

Page 5: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Why the droop?

The mean temp. of the lithosphere is cooler, and hence more dense, than the mantle. This urge to sink increases with lithospheric thickness, which increases with time subjected to cooling.

Page 6: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Age Distribution of the Sea Floor

Page 7: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Oceans of Kansas

Page 8: 4. Ocean Basin Shape: Contraction and Isostasyusers.clas.ufl.edu/.../L04_OceanBasinsIsostasy.pptx.pdfdroop of the ocean basin floor with distance from the spreading center. • This

Introduce Problem Set #1