Download The Paleozoic/Mesozoic tectonic evolution of Eastern Australia

The Paleozoic/Mesozoic tectonic evolution of Eastern Australia
Simon Williams, Jonathan Aitchison, Dietmar Müller
The geology of Eastern Australia records a series of orogenic events along the margin
of the supercontinent Gondwanaland. Musgrave and Cayley [1] used GPlates to
develop a new model for the tectonic evolution of this area during the SilurianDevonian. Magnetic anomaly maps [2] help to define the major Paleozoic-age
geological provinces and the shear zones that disrupt them – reconstructions are
constrained by bringing the anomalies that define these provinces into their original
alignment. One key question is: Which Eastern Australian “accretionary” belts are
allochthonous and which are autochthonous to the margin?
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Reconstruction of Eastern Australia in the Silurian (left), and revised APWP (right)
Previous Apparent Polar Wander Paths (APWPs) for Gondwana during the mid-Paleozoic
have relied on paleomagnetic data from the tectonically active parts of Eastern Australia. By
incorporating available paleomagnetic data into the GPlates reconstruction, Musgrave and
Cayley [1] revised this APWP taking these tectonic motions into account.
The project will involve acquiring various software and database skills, including
GPLates, including spatio-temporal data mining, Arc GIS, the Generic Mapping Tools, and
dealing with fossil and paleomagnetic databases. The SUCOGG Honours courses
(www.sucogg.org/honours.html) that go with these projects are Computational Tectonics,
Data Processing & Plotting using the Generic Mapping Tools (GMT), Advanced GMT
methods and Introduction to plate reconstruction and spatio-temporal data mining with
GPlates. This project will involve collaboration with the Geological Survey of NSW, and
prepare students both for working in the exploration industry as well as for a researchoriented career in government agencies or universities.
1. Musgrave, R. and Cayley, R., 2011. Unfolding an orocline restores Australian Siluro-Devonian
paleomagnetic poles. AGU Fall Meeting, San Francisco, GP11A-0991.
2. Milligan, P.R., Franklin, R., Minty, B.R.S., Richardson, L.M. and Percival, P.J., 2010, Magnetic
Anomaly Map of Australia (Fifth Edition), 1:15 000 000 scale, Geoscience Australia, Canberra.
The Mesozoic evolution of the Panthalassa “super ocean”
Dietmar Müller and Maria Seton
Everybody knows about supercontinents. However, there are superoceans as well
(Whittaker et al., 2008), and Panthalassa (Veevers et al., 1997;Arias, 2008), the ocean
basin which surrounded the supercontinent Pangaea, is probably the most famous one.
The problem is, we do not know much about its history. Recently, van der Meer et al.
(2012) suggested a bold approach to use very simple assumptions to use the mantle
structure imaged underneath the Pacific Ocean basin to reconstruct Panthalassa’s plate
boundary configurations through time. However, this model is extremely simplistic, and
has not been tested with geological data preserved along the Pacific rim, nor was it
determined whether the plate boundary configurations suggested in their paper are
actually feasible given the rules of plate tectonics.
Panthalassa at present and 200 million years ago. From van der Meer et al. (2012).
This project is not for the faint-hearted. It aims at producing the first self-consistent
model for the Mesozoic evolution of the Panthalassa Superocean, by amalgamating
information from accreted terranes, ophiolites, igneous rocks documenting ridge
subduction through time, and 3D mantle images from underneath the Pacific Ocean,
using the latest, not yet released version of the GPlates software, developed by the
EarthByte Group and its international collaborators. This brand new version of GPlates
allows the interactive 3D volume visualisation of seismic tomography with evolving
plate boundaries overlain (see poster display outside of GPlates Office 402).
The project will focus on the proto-Pacific’s Asian and North American boundaries, which
provide a rich record of subduction, back-arc basin formation and destruction, mid-ocean
ridge subduction and ophiolite obduction, providing constraints on the evolution of
Panthalassa. It will aim to construct a model for the evolution of this vast ocean basin, and
evaluate how Panthalassa spreading rates through time may have influenced mantle
convection, subduction rates, and regional sea level.
The project will involve acquiring various software and database skills, including
GPLates, spatio-temporal data mining, Arc GIS, the Generic Mapping Tools, seismic
tomography models and shell scripting The SUCOGG Honours courses
(www.sucogg.org/honours.html) that go with these projects are Computational Tectonics,
Data Processing & Plotting using the Generic Mapping Tools (GMT), Advanced GMT
methods and Introduction to plate reconstruction and spatio-temporal data mining with
GPlates. This challenging project will prepare the student to do anything afterwards.
References
Arias, C.: Palaeoceanography and biogeography in the Early Jurassic Panthalassa and Tethys Oceans,
Gondwana Res., 14, 306-315, 2008.
van der Meer, D., Torsvik, T., Spakman, W., van Hinsbergen, D., and Amaru, M.: Intra-Panthalassa Ocean
subduction zones revealed by fossil arcs and mantle structure, Nature Geoscience, 2012.
Veevers, J., Walter, M., and Scheibner, E.: Neoproterozoic tectonics of Australia-Antarctica and Laurentia
and the 560 Ma birth of the Pacific Ocean reflect the 400 my Pangean supercycle, The Journal of
Geology, 105, 225-242, 1997.
Whittaker, J. M., Müller, R. D., Roest, W. R., Wessel, P., and Smith, W. H. F.: How supercontinents and
superoceans affect seafloor roughness, Nature, 458, 1-4, 2008.
The Earth’s Paleozoic/Mesozoic tectonic and paleogeographic evolution
Dietmar Müller, Nicolas Flament, and Maria Seton
Continents and sedimentary basins through time have recorded fundamental Earth system
cycles, reflecting environmental change, migration of fauna and flora and shifting coastlines.
It was originally thought that successive advances and retreats of shallow inland seas mainly
reflect global sea level variations (eustasy). However, it is now well established that largescale surface morphology such as the high topography of the East African Rift, the low-lying
Amazon River Basin and the southwest to northeast tilt of the Australian continent are
strongly controlled by processes deep within the Earth. Quantifying the magnitude and timedependence of mantle-driven topography requires integrating geological data with coupled
models of the plate-mantle system. In turn, these models need to be validated with
observational data, such as published paleogeographic maps and paleobiology data.
The overarching aim of these projects is to understand the deep-seated driving forces of largescale topographic change, providing dynamic models of the Earth’s subduction history, deep
plume sources and dynamic topography for the Paleozoic-Mesozoic periods. The Paleozoic
follows the breakup of the supercontinent Rodinia after the end of the so-called Snowball
Earth period. Throughout the early Paleozoic, the Earth's landmass was broken up into a
substantial number of continents. Towards the end of the era, continents gathered together
into the supercontinent Pangaea.
We offer two Honours projects focussed on building models for the Paleozoic/Mesozoic Earth
using the software GPlates, and using geological observations to test geodynamic models,
which predict mantle convection patterns and surface uplift/subsidence through time:
Project 1: The evolution of proto-Atlantic/Indian ocean basins and marginal seas in
the Cambrian to Devonian
Project 2: The evolution of proto-Atlantic/Indian ocean basins and marginal seas in
the Carboniferous to Jurassic
They will address the following questions:
 How were ocean basins, including back-arc basins, created and destroyed between the
Cambrian and Jurassic periods?
 How have the fundamentally different plate tectonic configurations before and during/after
the assembly of the supercontinent Pangea affected subduction history, the history of midocean ridge system evolution, mantle convection patterns and ultimately regional sea level
fluctuations?
The projects will involve acquiring various software and database skills, including GPLates,
including spatio-temporal data mining, Arc GIS, the Generic Mapping Tools, shell scripting,
dealing with the paleobiology database, as well as learning the basics of geodynamic
modelling. The SUCOGG Honours courses (www.sucogg.org/honours.html) that go with
these projects are Computational Tectonics, Data Processing & Plotting using the Generic
Mapping Tools (GMT), Advanced GMT methods and Introduction to plate reconstruction and
spatio-temporal data mining with GPlates. These projects will prepare students both for
working in the exploration industry as well as for a research-oriented career in government
agencies or universities.
Establishing the geological connections between Australia and its neighbours in Rodinia using
geochemical and geophysical data
Supervisors: Dr Tom Landgrebe, Dr Derek Wyman, Dr Simon Williams
Several Rodinia-era tectonic plate reconstruction models have been proposed based on a
variety of datasets, consistently showing close spatial relationships between Australia and
continents such as North America and South China. In this project promising candidate
continental pairs are to be studied in conjunction with geophysical and aged geochemical
datasets assembled in the vicinity of the pertinent crustal elements. After reconstruction of all
the data, the next step is to establish whether the neighbouring cratons share common
geological settings based on geochemical and geophysical data coherency. Such a process
would investigate various alternative Rodinia models (e.g. SWEAT, AUSWUS, AUSMEX, the
'Missing Link' model) and discriminating between these models, as well as suggesting possible
local modifications to plate alignments. The final outcome of this project will be a detailed
analysis of how different Rodinia reconstructions can reconcile the studied geochemical and
geophysical data, and of the implications that these shared geological settings may suggest,
such as those pertaining to mineral systems.
The project will make use of the frontier GPlates plate reconstruction software, together with a
number of advanced spatial data analysis and data mining tools for visualising, interacting-with
and quantitatively analysing the various datasets.
Geodynamic controls on ore-deposit formation
Supervisors: Dr Tom Landgrebe, Dr Simon Williams, Dr Derek Wyman (EarthByte Group)
Relationships between metal deposits and both divergent and convergent margin processes
have been known for many decades. However, the challenge still remains to understand the
way in which "geodynamic niches" such as slab windows, rapid convergence, or phases of flatslab subduction, control the formation of ore deposits. The project will make use of the
Earthbyte Group’s global plate model and plate tectonic reconstruction software ‘GPlates’. In
particular, new methodologies being developed within GPlates to model continental
deformation and apply data mining methodologies to analyse the relationship between ore
deposit formation and the geodynamic evolution around the eastern margins of the Pacific
(Andes and North American convergent margins).