Who are the SGTSG?

The Specialist Group for Tectonics and Structural Geology is a subdivision within the Geological Society of Australia, a non-profit organisation that promotes, advances and supports Earth Sciences in Australia. The GSA is a communication channel for Earth Scientists and a vehicle to help foster engagement with the wider public about the underpinning roles Earth Science plays in enabling a prosperous and sustainable society.

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Geological Society of Australia membership is spread across Government employees, Academia (University-based researchers), Teachers and the Private Sector and the Society communicates geoscience research and knowledge via subscription-based peer-reviewed scientific journals, periodicals and special publications. Much of this information is freely available on the Geological Society of Australia website: https://www.gsa.org.au/

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Earth Science is a very broad field and so much specialisation exists within it. The SGTSG caters for the plucky breed of geologist and/or geophysicist who specialises in trying to understand the deformation history of rocks over millions of years and the relentless Earth processes that cause that deformation to occur (for example the continent-collisions that result from Plate Tectonics).

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Members of the SGTSG are the kinds of people who definitely find a car far more interesting after it’s been crushed into a cube of twisted metal. Its far less challenging to understand a sparkling new car that’s sitting pristine on a showroom floor.

Structural geologists enjoy trying to systematically unravel damage in order to reconstruct original shapes, and then use that information to deduce the setting of the original rock formation and the geological processes that might have caused it to have been changed into its present appearance.

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And so, every 2 years, the SGTSG chooses a different location somewhere in Australia with good geology, good food, good accommodation, and a good community, to spend several days arguing and discussing about how we think the Earth works and how the rocks beneath our feet might have formed.

Why King Island in 2022? 

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Bass Strait has long presented challenge to understanding the relationships between Tasmanian geology and the geology of mainland Australia – it’s harder to study rocks when there is an ocean on top of them.

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If the geology on either side of Bass Strait was much the same the intervening water wouldn’t present a big problem. But the rocks on either side aren’t the same. Some rocks in Tasmania – particularly western Tasmania – are VERY different to those exposed in Victoria.

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Solving this puzzle has been a decades-long challenge. King Island is a critical ‘halfway house’ in this story. Within sight of western Tasmania and virtually within sight of Cape Otway, the challenge has been to understand why the appearance of the geology changes so much between Tasmania and Victoria, what – if any – geology can be traced between the two States, and how the geology of King Island fits into that picture.

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Some King Island geological sequences look very similar to those seen in South Australia and on other continents as well, adding to the geological mystery.

The only way to understand ancient and complicated rocks such as those exposed on King Island is to stand on them and argue endlessly about them. And this is what the SGTSG members are looking forward to doing on King Island in February 2022. 

We want to use the features preserved in the rocks to ‘time-travel’ over 550 Million to 1200 Million years back in time to when the bedrock of King Island was originally being formed, and then consider how the Earth looked back then and where King Island (and Tasmania and Victoria and South Australia) sat within it. The deformation of rocks is governed by the laws of physics and so insights from King Island geology can potentially be applied equally elsewhere on Earth….and vice versa. This is how geology works.    

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The SGTSG Conference schedule includes a free Public Lecture that geologists and non-geologists should find engaging:

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King Island – a critical cog in the complex machine that is Australian geology. How King Island geology helps link Tasmania to the mainland and helps explain Earth geological history.

The SGTSG Committee notes that the King Island scheelite (tungsten) mine at Grassy is currently undergoing re-development.  With over 100 years of mining and development history, an existing (since 2012, updated in late 2020) mineral reserve of 4.43 million tonnes at a grade of 0.92% WO3 (scheelite) and over 7km of prospective geology already defined within the Exploration Licence, the Tungsten deposit is already well understood and is not a specific topic of study for the SGTSG or a motivation to hold the SGTSG conference on King Island.