Post-Pangea global plate kinematics and geodynamic implications for Southeast Asia
Access status:
USyd Access
Type
ThesisThesis type
Doctor of PhilosophyAuthor/s
Zahirovic, SabinAbstract
Modern plate reconstructions, with evolving plate boundaries that document the breakup of Pangea hold vital clues for the factors affecting plate motions. Previous studies have evaluated the present-day plate arrangements and velocities, and therefore cannot capture the inherent ...
See moreModern plate reconstructions, with evolving plate boundaries that document the breakup of Pangea hold vital clues for the factors affecting plate motions. Previous studies have evaluated the present-day plate arrangements and velocities, and therefore cannot capture the inherent plate behaviour over deep geological time. A handful of studies have used plate reconstructions to alleviate these temporal shortcomings, but have been limited by the small number of plate reconstruction timesteps, leading to conflicting suggestions that continents may both inhibit or promote fast plate motions. This thesis demonstrates that increasing portions of continental plate area significantly reduces plate velocities when using a post-Pangea plate reconstruction framework. However, plates with large continents exhibit short-lived (~5-10 Myr) but high-amplitude anomalous accelerations that are often related to plume head arrivals. The breakup of Pangea opened the vast Atlantic, Indian and Southern Oceans at the expense of the equatorial oceanic gateway that linked the Tethys and (proto-) Pacific. Refined reconstructions of this lost oceanic gateway, in the absence of preserved oceanic crust, required a synthesis of geological data from the continents that travelled on these now-subducted plates. By coupling the refined plate reconstructions to numerical mantle flow simulations, this thesis demonstrates that the short-lived (~10-15 Myr) subduction hiatus from the accretion of continental blocks at ~80 Ma along southern Sundaland resulted in ~200 m of dynamic uplift of the continental promontory, which was likely responsible for the enigmatic Late Cretaceous to Paleocene regional unconformity. The approaches presented in this thesis highlight the need for data-driven global plate reconstructions, coupled to geodynamic simulations of mantle flow in a global spherical mantle shell, to study both the global plate-mantle system but also address regional geological enigmas.
See less
See moreModern plate reconstructions, with evolving plate boundaries that document the breakup of Pangea hold vital clues for the factors affecting plate motions. Previous studies have evaluated the present-day plate arrangements and velocities, and therefore cannot capture the inherent plate behaviour over deep geological time. A handful of studies have used plate reconstructions to alleviate these temporal shortcomings, but have been limited by the small number of plate reconstruction timesteps, leading to conflicting suggestions that continents may both inhibit or promote fast plate motions. This thesis demonstrates that increasing portions of continental plate area significantly reduces plate velocities when using a post-Pangea plate reconstruction framework. However, plates with large continents exhibit short-lived (~5-10 Myr) but high-amplitude anomalous accelerations that are often related to plume head arrivals. The breakup of Pangea opened the vast Atlantic, Indian and Southern Oceans at the expense of the equatorial oceanic gateway that linked the Tethys and (proto-) Pacific. Refined reconstructions of this lost oceanic gateway, in the absence of preserved oceanic crust, required a synthesis of geological data from the continents that travelled on these now-subducted plates. By coupling the refined plate reconstructions to numerical mantle flow simulations, this thesis demonstrates that the short-lived (~10-15 Myr) subduction hiatus from the accretion of continental blocks at ~80 Ma along southern Sundaland resulted in ~200 m of dynamic uplift of the continental promontory, which was likely responsible for the enigmatic Late Cretaceous to Paleocene regional unconformity. The approaches presented in this thesis highlight the need for data-driven global plate reconstructions, coupled to geodynamic simulations of mantle flow in a global spherical mantle shell, to study both the global plate-mantle system but also address regional geological enigmas.
See less
Date
2014-12-01Licence
The author retains copyright of this thesis. It may only be used for the purposes of research and study. It must not be used for any other purposes and may not be transmitted or shared with others without prior permission.Faculty/School
Faculty of Science, School of GeosciencesAwarding institution
The University of SydneyShare