Pressure‐Driven Poiseuille Flow Inherited From Mesozoic Mantle Circulation Led to the Eocene Separation of Australia and Antarctica

I L Stotz,A Tassara,G Iaffaldano

doi:10.1029/2020jb019945

Abstract

AbstractThe separation between Australia and Antarctica occurred during the final stages of the break‐up of Pangea. Reconstructions of the rifting of the Australian plate away from Antarctica show fast spreading rates since Mid‐Eocene (45 Ma). These reconstructions can be used to understand and quantify the forces driving the Australia/Antarctica separation, and to test hypotheses on mechanisms that may be of shallow (i.e., lithosphere) or deep (i.e., mantle) origin. Analytical calculations indicate that plate‐boundary forces are highly unlikely to be a plausible candidate to explain such a separation. Thus, we use a recently developed global coupled models of mantle and lithosphere dynamics, here we show that this event, whose kinematics are reproduced in our models within the bounds of the reconstruction uncertainties, owes to a significant degree to the pressure‐driven asthenospheric Poiseuille flow associated with the mantle buoyancy field inherited from viscous circulation history throughout the Mesozoic. On the contrary, in simulations when such a buoyancy field is replaced by another one resulting from a random distribution of mantle temperature–thus not representative of Earth’s mantle circulation history–the rapid northward motion of Australia does not occur. Similarly, suppressing contemporaneous plate‐boundary processes (i.e., subduction of the Pacific ridge at the Aleutians and healing of the India‐Australia ridge) from our models does not have a noticeable effect on the Australia‐Antarctica kinematics. Thus, a pressure‐driven Poiseuille mantle flow must be considered, at least in this example and possible elsewhere, as a main driver of plate tectonics.

Highlights

The history of divergence of the Australian plate relative to Antarctica has been the focus of several previous studies (e.g., Cande & Stock, 2004; Jacob & Dyment, 2014; Powell et al, 1988; Royer & Sandwell, 1989; Smith & Hallam, 1970; Tikku & Cande, 1999; Whittaker et al, 2013; Williams et al, 2011)
We use a recently developed global coupled models of mantle and lithosphere dynamics, here we show that this event, whose kinematics are reproduced in our models within the bounds of the reconstruction uncertainties, owes to a significant degree to the pressure-driven asthenospheric Poiseuille flow associated with the mantle buoyancy field inherited from viscous circulation history throughout the Mesozoic
The South Indian Ocean formed as a result of the separation between Madagascar and Indian from Africa. During this phase the African continent has experienced several phases of uplift and burial (Burke & Gunnell, 2008), which are thought to be caused by variations in the mantle densities underneath the continent–this is commonly referred to in the literature as dynamic topography (e.g., Sengoer, 2001). (iii) The third and final phase of the break-up of Pangea occurred in the Paleocene to Oligocene times (∼65 to ∼23 Ma), when Greenland separated from North America, and Australia separated from Antarctica

Summary

Introduction

The history of divergence of the Australian plate relative to Antarctica has been the focus of several previous studies (e.g., Cande & Stock, 2004; Jacob & Dyment, 2014; Powell et al, 1988; Royer & Sandwell, 1989; Smith & Hallam, 1970; Tikku & Cande, 1999; Whittaker et al, 2013; Williams et al, 2011). (ii) A second break-up phase began in the Early Cretaceous between 150 and 140 Ma, when the terrains of Pangea started separating into multiple continents, such as South America and Africa During this phase, the South Indian Ocean formed as a result of the separation between Madagascar and Indian from Africa. During this phase the African continent has experienced several phases of uplift and burial (Burke & Gunnell, 2008), which are thought to be caused by variations in the mantle densities underneath the continent–this is commonly referred to in the literature as dynamic topography (e.g., Sengoer, 2001). Continental Australia experienced events of uplift and subsidence (Czarnota et al, 2014)

Results

Discussion

Conclusion