Explorers unpack Earth’s sedimentary basins

Sedimentary basins    that exist over vast sections of Earth’s surface are formed by long-term subsidence of continents due to tectonic extension, which creates accommodation space for infilling sediments that are eroded from nearby mountain ranges. Over time, natural resources then accumulate within these basins by various geological processes. Pictured: Cross-bedding in Permian fluvial sandstones on the Tasman Peninsula, Australia. These sandstones were deposited by east flowing rivers in Gondwanaland and include the Cygnet Coal Measures, which originated from Permian rainforests. Image:    Prof Dietmar Müller   .

Sedimentary basins that exist over vast sections of Earth’s surface are formed by long-term subsidence of continents due to tectonic extension, which creates accommodation space for infilling sediments that are eroded from nearby mountain ranges. Over time, natural resources then accumulate within these basins by various geological processes. Pictured: Cross-bedding in Permian fluvial sandstones on the Tasman Peninsula, Australia. These sandstones were deposited by east flowing rivers in Gondwanaland and include the Cygnet Coal Measures, which originated from Permian rainforests. Image: Prof Dietmar Müller.


Sedimentary basins around the world are critical to sustaining modern life on Earth. These basins can be thought of as containers that hold water, minerals, energy, and can potentially be used to store carbon dioxide. Unpacking how they form, and where those resources and storage opportunities may lie is a sizeable feat for the best of us.

Indeed, the best of us are working on this, using specialist software like AuScope’s Underworld and GPlates software codes, to bring complex models of these large
tracts of sunken Earth to life.


Introducing the Basin Genesis Hub

In 2015, a team of scientists from Sydney University, The University of Melbourne, Curtin University, Geoscience Australia, and the California Institute of Technology, with five international industry partners, has gathered to form the Basin Genesis Hub (BGH), a five-year program that is funded by the Australian Research Council to better understand Earth’s sedimentary basins.

Since, they have been developing technologies that model Earth processes across a wide range of spatial and temporal scales — from the deep churning interior of our planet to evolution of rivers and topography on the surface — to translate this new body of knowledge into practice for decision makers and end-users in basin exploration and management. In particular, they have focussed on understanding basins along Australia’s North West Shelf, in New Guinea, and the Atlantic Ocean continental margins, as well as other locations around the world.

In Australia’s North West Shelf region, Dr Sara Morón-Polanco has been combining different geological datasets — seismic to biostratigraphic — and using specialist Badlands software, developed by Dr Tristan Salles within the BGH, to simulate how ancient river delta systems have deposited sediments into the hydrocarbon-rich Carnarvon Basin over millions of years.

We can see river systems depositing sediments into basins today, as shown in this image of China’s Yellow River, but modelling this complex sedimentation and deformation process numerically is very challenging.

China’s Huang He (Yellow River) is the most sediment-filled river on Earth. Image:    NASA

China’s Huang He (Yellow River) is the most sediment-filled river on Earth. Image: NASA

Sara’s work using sophisticated simulation software such as Badlands is critical to help decode the complexity of ancient geological processes that have operated along the North West Shelf and can be translated to other basins that underlie approximately half of the Australian continent.

Much of these advances have also relied on cross-institutional team work, where Prof Chris Elders and the Curtin team have been busily mapping our continent’s subsurface, while Dr Romain Beucher and the Melbourne team have been fine-tuning numerical models of how the continent has deformed over hundreds of millions of years.

Left:    Dr. Sara Morón-Polanco   ’s research are in the Carnarvon Basin in Australia’s north west shelf. Credit:    Myra Keep   , AGSO/Geoscience Australia. Right: Output of deltaic simulations generated in Badlands, which are used to better understand what controls the sedimentary patterns we observe in ancient deltas — critical to unlocking the vast amounts of hydrocarbons hosted in these types of reservoirs. Credit:    Dr Sara Morón-Polanco   .

Left: Dr. Sara Morón-Polanco’s research are in the Carnarvon Basin in Australia’s north west shelf. Credit: Myra Keep, AGSO/Geoscience Australia. Right: Output of deltaic simulations generated in Badlands, which are used to better understand what controls the sedimentary patterns we observe in ancient deltas — critical to unlocking the vast amounts of hydrocarbons hosted in these types of reservoirs. Credit: Dr Sara Morón-Polanco.

Meanwhile, Prof Dietmar Müller, A/Prof Patrice Rey and Dr Sabin Zahirovic have been been modelling basin development in the New Guinea region at the northern margin of the Australian continent, which was torn apart during the breakup of the Pangea supercontinent around 200 million years ago, and has since been crushed by continental collision processes.

By understanding the most recent supercontinent assembly and breakup, the research lays down the foundations for better understanding even older supercontinents. As plate tectonics influences the planet’s habitability, climate, sea level, ocean circulation, and other key planetary systems, it becomes important to integrate this new generation of numerical models to also help explain the formation of basins, and the energy and mineral deposits that they contain.

This animation shows how a plate tectonic reconstruction (Zahirovic et al., 2015) can be assimilated as a boundary condition to a numerical mantle flow model in CitcomS using the approach of Bower et al. (2015) and model setup of Hassan et al. (2016).

In the third BGH stream, Dr Claire Mallard has been using Underworld to develop dynamic Earth models and quantify the effect of mantle and lithosphere interactions on basin evolution. Claire, along with A/Prof Patrice Rey and Dr Romain Beucher, have used the first Underworld models that capture both the deformation of Earth’s crust and simultaneously model erosion and deposition that results.

This new capability is world-leading, and for the first time has allowed Claire and the team to investigate how continental breakup and collisions produce mountain belts where rocks are eroded to sediments, and carried by river networks to be deposited in sedimentary depocenters. The models that the team have produced are the first ever to link tectonics/geodynamic with erosion and deposition of sediments.

Even the best numerical models need data for ground-truthing. This is where Australia’s long-term investment has paid off, as the Basin Genesis Hub team can access decades of data collected and interpreted by Geoscience Australia. The Hub team, working closely with Dr Nadege Rollet and Dr Karol Czarnota from Geoscience Australia, are stitching together vast databases of the sub-surface architecture of our continent, allowing the numerical model predictions to be tested and fine-tuned.

Modelling mantle and lithospheric interactions together with surface observations in 3D using fully coupled Underworld-Badlands models. These models are the first to capture both the tectonics/geodynamics, as well as the erosion and deposition of sediments. Image:    Dr Claire Mallard   .

Modelling mantle and lithospheric interactions together with surface observations in 3D using fully coupled Underworld-Badlands models. These models are the first to capture both the tectonics/geodynamics, as well as the erosion and deposition of sediments. Image: Dr Claire Mallard.

Achievements so far

For the first time, deformation of continental crust is being considered in global plate tectonic reconstructions. This will enable the team to link deep Earth mantle convection with the stretching and crumpling of continental crust and the resulting tectonic motions on the surface as well as the role of erosion and deposition in modifying continental landscapes.

The technologies and models being developed will all be open source with detailed documentation leading to a robust community toolbox to develop a deep-time digital Earth. These models will help de-risk industry decisions in exploring for energy and mineral resources but will also provide a platform to study sea level change, groundwater flow in aquifers, and examine biogeographic evolution pathways on a regional and global scale.

This animation shows the evolution of deformation (rifting and orogenesis) during the breakup of the Pangea supercontinent. This is the first global plate tectonic reconstruction that goes beyond the simplifying assumption of rigid lithospheric plates, as well as incorporating an optimised absolute reference frame. Citation: Müller, R. D., Zahirovic, S., Williams, S.

The plan ahead

For the remainder of the project, the team aims to further develop continental-scale basin evolution models, linking the AuScope-developed softwares GPlates and UnderworldS (developed by AuScope Simulation and Modelling Leader Prof Louis Moresi and his group), and utilise the emerging ATOM Atmospheric-Ocean modelling software that provides continental precipitation through geological time, and drives continental erosion and sediment transport while continents are moving through different climate zones.

In the future, the team aims to model long-term landscape continental evolution so that we can understand sedimentary basin history and structure in a variety of regions throughout the world. Their long-term aim is to develop Earth system models that link advances in climate, oceanic and atmospheric sciences to solid Earth evolution over billions of years of planetary evolution.

 

 
 

AUTHORS

This article has been produced by Jo Condon of AuScope, and Dr Sabin Zahirovic and Prof Dietmar Müller from Sydney University. We thank them both, and also Dr Claire Mallard from Sydney University and
Dr Sara Moron-Polanco from The University of Melbourne/Sydney for providing key inputs.


MORE INFO

The ARC Basin GENESIS Hub: connecting solid Earth evolution to sedimentary basins: a technical article in
The Australian Society of Exploration Geophysicists’ Preview which explains the software and new basin modelling workflows being developed in this research centre

Sedimentary Basins: explaining an important source of groundwater in Australia by Geoscience Australia

Discover GPlates, Underworld,
&
Badlands software codes

NewsJo CondonSAM