Expedition to the Coral Sea to sample underwater volcanoes

Sep 3, 2019

One of the world’s most extensive intraplate volcanic regions is located in Eastern Australia, including the world’s longest continental hotspot trail and two parallel trails offshore (Tasmantid and Lord Howe Seamount chains). Hotspot trails are thought to arise from mantle plumes, whose episodic eruptions have caused environmental crises affecting the world’s atmosphere (release of gas and aerosols), biosphere (mass extinctions) and hydrosphere (altering ocean circulation and chemistry). Identifying mantle plume eruptions in the geological record provides us with a window into the deep Earth.

Navigation through the Coral Sea. Each magenta dot indicates a dredge site to scoop up rocks from the sea floor.

This project, led by Maria Seton, Jo Whittaker, & Simon Williams seeks to determine the extent of plume activity in the Coral Sea and explore the factors controlling the geochemical make-up of the mantle, will facilitate breakthroughs in answering some of the most challenging questions in Earth Sciences such as how the deep Earth communicates with the surface, what controls the heterogeneity in mantle chemistry and the validity of the mantle plume hypothesis itself.

Sorting freshly dredged rocks on the deck of the RV Investigator

We collected a lot of rocks (105 buckets of them) but one of the more impressive catches was this ignimbrite snatched from the Louisiad Plateau. This is usually an indicator for a large igneous province, or LIP, which are regions where lots of lava has erupted over a large area.

This ignimbrite could represent the start of the Tasmantid Seamount chain. We'll know for certain when we analyse its geochemistry and find its age.

Some scientists have reasoned that one should observe a LIP at the start of a volcanic hotspot chain. If the Louisiad Plateau is a LIP, then it may be that the entire region we are sailing over is the birth place of the Tasmantid Seamount chain - and THAT is a very exciting finding!

Voyage summary

  • Travelled (and mapped) 8600 km of sea
  • 23 seamounts
  • 56 dredges
  • 3 lost dredges (RIP Snappy)
  • 105 buckets of rocks and sediments
  • 14000 seabirds documented
  • engaged with 1000 school pupils
  • 3 newly identified species of coral
  • Discovered two shipwrecks from the second world war

The Friend Ship

No matter how you measure the success of the voyage, we have done an exceptional job. But what is most remarkable on a 28 day voyage is that everyone has gotten along so well. You could say that we have formed a family of sorts out of our shared experience.

Group photo on the front deck

Media coverage

ABC News “CSIRO ship scours the Coral Sea depths to reveal trove of scientific wonders”

ABC News “CSIRO’s Investigator voyages through Coral Sea to map seafloor and unlock seabird secrets”

Sydney Morning Herald “Every day of CSIRO voyage revealed new secrets of the deep”

Brisbane Times “Every day of CSIRO voyage revealed new secrets of the deep”

The West Australian “Australian scientists discover new coral species”

News.com.au “Australian scientists discover new coral species”

Mirage News “Coral Sea voyage uncovers volcanic secrets of seafloor”

Cairns Post “CSIRO’s RV Investigator sets sail from Cairns to study underwater volcanoes in Coral Sea”

The New Daily “Bird experts unlock mysteries of Australia’s unmapped ocean”

For more, check out my blog at https://www.benmather.info/blog/2019-investigator/

Ben Mather

Postdoc in the EarthByte Group at Sydney Uni