Geologists have used geological data sets from ships to produce the world’s first digital map of the seafloor’s lithology.
The map, produced by a team from the University of Sydney's School of Geosciences, shows more complex geological features and significant differences in the global lithological distribution from earlier maps.
“In order to understand environmental change in the oceans we need to better understand what is preserved in the geological record in the seabed,” said research leader Dr Adriana Dutkiewicz.
In the study, published in the journal Geology, the team analysed 14,500 seafloor samples – collected over half a century – from research ships and applied algorithms to turn the data into a continuous digital map.
The map shows that sediment distribution is more complex, with significant deviations from earlier hand-drawn maps from the 1970s, and that major lithologies occur in different proportions globally. Some of the most significant changes to the seafloor geology the scientists discovered are in the oceans surrounding Australia.
Dr Dutkiewicz said: “The old map suggests much of the Southern Ocean around Australia is mainly covered by clay blown off the continent, whereas our map shows this area is actually a complex patchwork of microfossil remains. Life in the Southern Ocean is much richer than previously thought.
“The deep ocean floor is a graveyard with much of it made up of the remains of microscopic sea creatures called phytoplankton, which thrive in sunlit surface waters. The composition of these remains can help decipher how oceans have responded in the past to climate change.”
By using pigment-calibrated chlorophyll satellite data, the team also observed a group of phytoplankton called diatom oozes – which produce about a quarter of the oxygen on Earth – and found that they accumulate on the seafloor rather than on the surface.
“Our research opens the door to future marine research voyages aimed at better understanding the workings and history of the marine carbon cycle. Australia's new research vessel is ideally placed to further investigate the impact of environmental change on diatom productivity. We urgently need to understand how the ocean responds to climate change,” added Dr Dutkiewicz.
The scientists believe the map will lead to robust reconstructions and predictions of climate change and its impact on the ocean environment.
“Recent images of Pluto's icy plains are spectacular, but the process of unveiling the hidden geological secrets of the abyssal plains of our own planet was equally full of surprises,” said research associate Dr Simon O'Callaghan.