Ocean Gateways and Climate Change

Overview:

Week 5 Overview:

  • Understand the hypsometric curve

  • Understanding of the continental drift theory, what it is based on and its shortcomings

  • Understanding of basis of the theory of plate tectonics – key observations that led to its development

  • Understanding how plate tectonics works (especially plate rotations)

  • Understanding of how continental rifts lead to ocean basin formation 

  • Understanding of the tectonic and magnetic structure of ocean crust

  • Rigid plates versus plate deformation

  • The Wilson Cycle

Week 6 Overview:

  • Plate tectonics wrapup – subduction zone volcanism, plate collisions

  • Understand ocean topographic features

  • Understand hypsometry and isostasy

  • Understand the origin and distribution of different ocean sediment types

  • Understand the Carbonate Compensation Depth

  • Understand how deep ocean currents modulate the distribution of deep-sea sediments

Week 7 Overview:

  • Understand the formation of submarine channels, fans and turbidites

  • Understand the formation of some sedimentary resources including sand, salt, metalliferous nodules and methane

Week 8 Overview:

  • Understanding the drivers of ocean and atmosphere circulation

  • Understanding the Coriolis force

  • Understanding wind forcing of ocean circulation

  • Understanding deep water formation

  • Understanding the Ekman spiral

  • Understanding upwelling

Week 9 Overview:

  • Understand governing processes of long-term climate change

  • Understand observational proxies for long-term climate change

  • Understand features of Pliocene climate

Week 5

  • What is the antartic climate Current → strongest and largest

  • Tasman Gateway opened ~34 My ago. (between antarica and australia)

  • Wind driven current that extends from sea level to the sea bed

  • Drake passage and obstical

  • The ocean conveyor belt

  • Strong westerly winds over the southern ocean drive eastward surface flow

  • ACC gives insight into the arrangement of continets and ocean basins → long term oceanic circulation, global sea levels and climate change

  • ACC is important for our understanding of how, why and to what degree our earths climate changed in the deep geologic past and how this compares with future change


Lecture 10 - Plate Tectonics: Tectonic features of ocean basins

  • Volcanism → plate tectonics

  • Crations very old → millions of years old

  • 500 Ma - Gondwanaland

  • 1000 Ma - Rodina

  • First person to relies open and closing of ocean basins → Tuso Wilson

  • ocean basins have opened and closed

  • geological evidence → suture zones, ophiolites, Mountain belts (orogens)

  • Ocean basin evidence → seafloor spreading & magnetic stripes, Passive margins, Active margins & trenches

  • Tectonic process evidence → Subduction zones & volcanic arcs, deep subduction zone earthquakes

  • Early - stage evidence → continental rifting (e.g East Africa)

  • plate Boundaries → convergent, divergent and transform

  • Mid ocean ridges → plates pull apart; decompression melting. produces basaltic magma (low viscosity) effusive eruptions. Pillow lava.

  • Subduction zones → Slab releases water and flux melting in mantle. → produces andesitic dacitic magma (silica rich), explosive eruptions, forms volcanic arcs

  • Magma Plumes →

  • Continetial breakup - East Africa

  • deep sea mantle plume