How Australia and India broke up—100 million years ago

Dr Joanne (Jo) Whittaker, Institute for Marine and Antarctic Studies, University of Tasmania, Hobart

Dr Joanne (Jo) Whittaker likes to solve jigsaw puzzles. Now this marine geoscientist is tackling the biggest puzzle on the planet—the formation of continents.
WithSDP_0059 the help of Australia’s national marine research vessels, and now her L’Oréal Fellowship, Jo is reconstructing how the Indian, Australian and Antarctic tectonic plates separated over the past 200 million years, forming the Indian Ocean and the continents as we see them today. This information will help us model climate change better, find new gas resources, and understand the dynamics of the land in which we live.

The piece of this jigsaw she is now working on centres on two underwater plateaux, the Batavia and Gulden Draak Knolls, towering about 3000 metres above the Perth Abyssal Plain (PAP), which is around 1600 kilometres off the coast of Geraldton in Western Australia. In November 2011, Jo’s team mapped and sampled rocks from both knolls. Based on the evidence so far, Jo says, it looks like they split from the margins of the moving Indian Plate about 100 million years ago.

But in order to be sure, and to properly understand the sequence of development of the Indian Ocean Basin, Jo needs to have those rocks properly dated and identified. That’s the use to which she will put the $25,000 prize she receives as one of this year’s three L’Oréal Australia and New Zealand For Women in Science Fellows.

“The seas surrounding Australia harbour unique ecosystems and support valuable industries such as oil and gas production, fisheries and tourism,” says Jo. “Despite our reliance on these industries and our penchant for living along the coast, large tracts of Australia’s surrounding ocean floor remain unknown and unexplored.”

The recent project began with a successful bid for time on Australia’s Marine National Facility research vessel Southern Surveyor to explore the PAP. Two hundred million years ago the plain was the point at which India, Antarctica and Australia connected to form Gondwanaland. And then they broke apart. Satellite gravity data suggested the PAP contained two undersea plateaux together about half the size of Tasmania in area. The ship set out to locate them and collect evidence that could suggest how they had formed.

“It’s really exciting to go where no-one has been, and see things no-one has ever seen before,” Jo says. Unfortunately that didn’t happen for her. She was on maternity leave when the voyage took place—although constantly in contact with her team.

The rock samples they scraped off the sides of the two knolls, between 1000 and 1500 m underwater, were clearly continental and may have formed about 20 kilometres beneath Australia. Jo thinks the ultimate separation of the Knolls from India was the result of an upwelling, the Kerguelen volcanic plume, which is an important part of the puzzle of the development of the Indian Ocean.

She now has to fit that piece into the broad reconstruction of the Indian Ocean basin being pulled together by a team of which she is a key member. “This model has to consistently account for geophysical and geological data across five continents, 200 million years and the entire Indian Ocean.” And it draws upon Jo’s ability to combine different scales of mapping to account for the role of forces in the mantle in driving what happens at the surface.

At base level, says Jo, such work provides us with an understanding of how our planet works—but it also has much more immediate uses. “It feeds into oil and gas exploration. A lot of oil and gas and other resources are formed on the continental margins, so the industry needs to know where the continents were, and how the margins evolved through time.” Some of Jo’s work has been sponsored by the Norwegian oil company Statoil.

“The research feeds into palaeoclimate models that go back tens of millions of years. A big part of getting palaeoclimate models right is getting ocean currents right. So you need to know what the geometry of the ocean basins was.”

Jo began answering similar sorts of questions during her PhD studies under the guidance of Prof Dietmar Müller at the University of Sydney. She and her colleagues came up with a surprising, and internationally heralded, explanation for a series of geological events that happened a long way apart about 50 million years ago—it turned out they were linked.

Jo was looking at magnetic anomaly data for the area between Australia and Antarctica. This data measures local variations in the Earth’s magnetic field caused by differences in the underlying rock, and can be used to determine undersea ridges where seafloor spreading is taking place. In this case Jo was looking at the breakup of the two continents. “There were some problems with the existing reconstructions,” she says.

Then Jo had the bright idea that, about 50 million years ago, something had shifted the jigsaw around. Australia, which had been moving in a north-westerly direction relative to Antarctica until this time, began to move due north with quite a sudden change in motion. Even more interesting, it was matched at the same time by a similar bend in the line of formation of undersea volcanoes or seamounts of the Emperor-Hawaii chain which extends across the northern Pacific from near Japan to the southern islands of Hawaii.

But what could have caused two such cataclysmic changes so far apart at around the same time? The answer, it turned out, was right in Jo’s research group, in the work of Dr Maria Seton. Maria was studying an ancient mid-ocean ridge, which was destroyed when it plunged beneath an area stretching from Korea to north of Japan. “This event affected the motions of the entire hemisphere. It had a knock-on effect. You can see the same 50-million-year event in other plate systems. It’s just much more subtle.”

Perhaps it’s no surprise that Jo became interested in studying rocks. Her parents both had a science background, her father a biochemist at the CSIRO and her mother a science educator who developed curricula for TAFE courses. And she grew up north of Sydney on the fringes of rocky Ku-ring-gai Chase National Park. It became her backyard, and left her with a lifelong addiction to rock climbing.

But, interestingly, when Jo went to university, her first idea was to become an accountant. So she did a double degree in geology, and accounting and economics. By the end of her degree she recognised she had made a big mistake. So she went back to one of the science lecturers who had impressed her most, and asked whether she could do her honours year with him. That lecturer was Dietmar Müller, who was to become her PhD supervisor and mentor. Thus began the trail that has led her into the world of continental jigsaws.

Now, things are really working out. Recently moved to Hobart with her partner and young child and, with scope for plenty of rock climbing nearby, she has three data collection cruises scheduled over 16 weeks in 2014 on Australia’s Marine National Facility research vessel Investigator, and the Schmidt Institute’s RV Falkor.

Read the latest news about Dr Jo Whittaker

Qualifications

2008PhD (Geophysics), The University of Sydney
2005Master of Geophysics, Victoria University of Wellington, New Zealand
2003Bachelor of Science with Honours (Geology)/Bachelor of Commerce, The University of Sydney

Career highlights, awards, fellowships, grants

2013-presentMarine Geoscientist, Institute for Marine and Antarctic Studies, University of Tasmania
2013Edgeworth David Medal, Royal Society of NSW
2012-2013Chief investigator on three separate grants (from CSIRO and Schmidt Oceanographic Institute) for a total of 16 weeks’ ship time (worth almost $5.5 million) on Australia’s Marine National Facility research vessel Investigator
2011Invited speaker, 36th Professor Harry Messel International Science School: Light and Matter, Sydney
2010NSW Tall Poppy Award, Australian Institute of Policy & Science
2010Lead chief investigator on grant for three weeks’ ship time (worth almost $1 million) on Australia’s Marine National Facility research vessel Southern Surveyor, funded by CSIRO and Statoil
2010Invited speaker, Austral Portals Symposium, New York, USA
2009Invited speaker, Marine Geoscience Leadership Symposium, Washington DC, USA
2009-2013Postdoctoral Research Fellow, The University of Sydney
2008-presentHonorary Research Fellow, University of Leeds, UK
2008-2009Principal Research Geodynamicist, GETECH, UK
2008Awarded “Best Oral Presentation” at the Third Eastern Australian Basins Symposium, Sydney
2007Postgraduate Research Prize, The University of Sydney
2007Invited speaker, Emerging Plays in Australasia, Geological Society of London
2005-2008Australian Postgraduate Award
2005-2007Demonstrator, University of Sydney
2005Seismic Field Officer, Geological and Nuclear Sciences, New Zealand
2004Graduate Research Scholarship, School of Earth Sciences, Victoria University of Wellington, New Zealand
2004Graduate Research Scholarship, Victoria University of Wellington, New Zealand
2004Demonstrator, Victoria University of Wellington, Wellington
2003Department of Marine Sciences Scholarship, The University of Sydney
2003Rio Tinto Mapping Prize, The University of Sydney
2003Consultancy Support Officer, Holmes Air Sciences, Sydney

Top five publications

Whittaker JM, Müller RD, Leitchenkov G, Stagg H, Sdrolias M, Gaina C and Goncharov A (2007) Major Australian-Antarctic plate reorganisation at Hawaiian-Emperor bend time, Science 318: 83–86. (Impact factor 31, 86 citations)

Whittaker JM, Müller RD, Roest WR, Wessel P and Smith WHF (2008) How supercontinents and superoceans affect seafloor roughness, Nature 456:938–941. (Impact factor 36, 9 citations)

Fielding CF, Whittaker JM, Henrys S, Wilson T and Naish TR (2008) Seismic facies and stratigraphy of the Cenozoic succession in McMurdo Sound, Antarctica: implications for tectonic, climatic and glacial history, Palaeogeography, Palaeoclimatology, Paleoecology 260(1–2):8–29. (Impact factor 2, 43 citations)

Whittaker JM (2009) The hydrangeas of plate tectonics, Nature Geoscience, 2:246–47. (Impact factor 12, 0 citations).

Whittaker JM, Müller RD, Sdrolias M and Heine C (2007) Sunda-Java trench kinematics, slab window formation and overriding plate deformation since the Cretaceous, Earth and Planetary Science Letters 255:445–457. (Impact factor 4, 30 citations)

 Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
 Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
 Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
 Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)
Dr Jo Whittaker (credit: L’Oréal Australia/sdpmedia.com.au)