The controls on palaeobathymetric boundary conditions for ocean basin evolution

• Main Author: Wright, Nicky Margaret
• Format: Thesis
• Language: unknown
• Published: The University of Sydney 2017
• Subjects: plate tectonics; palaeobathymetry; Pacific Ocean; sea level; Indian; Kerguelen; Pacific; Southern Ocean
• Online Access: http://hdl.handle.net/2123/17620

The persistent creation and destruction of ocean basins has a major influence on changes in palaeoclimate and long-wavelength changes in eustatic sea level in an ice-free world. The evolution of the world’s ocean basins is largely controlled by the history of plate tectonic motions; however, uncertainties in plate tectonic reconstructions are often ambiguous and enhanced into the past due to the loss of oceanic crust via subduction. This thesis comprises three chapters which collectively explore the plate tectonic and palaeoceanographic evolution of ocean basins. The Pacific Ocean basin has persisted as the largest ocean basin throughout the Mesozoic and Cenozoic and dominates reconstructions of the age and volume of ocean basins. I quantitatively refine the plate kinematic evolution of the Pacific Ocean basin since the Late Cretaceous. Based on these refinements to the Pacific Ocean basin relative plate motion model, and embedded within a global plate kinematic model, I investigate uncertainties in reconstructions of ocean basin volume and palaeobathymetry for the Mesozoic and Cenozoic, and assess its influence on eustatic sea level. Within a plate kinematic context, including recent models for Southern Ocean gateways, I additionally examine the evolution of palaeocean circulation in the Indian Ocean sector of the Southern Ocean from the Late Eocene to late Oligocene (36–23 Ma), using neodymium isotope records from fossil fish teeth obtained from Ocean Drilling Program Sites 744 and 748 (Kerguelen Plateau). The studies of this thesis highlight the uncertainties associated with reconstructions of ocean basins through geologic time, in particular, the age, depth, and volume of ocean basins. Refining the reconstructions of ocean basins and the uncertainties in these models has important implications for sea level, palaeocean circulation and palaeoclimate, as well as geodynamic implications.