A gigantic underwater volcanic structure known as the Melanesian Border Plateau (MBP) located north of Fiji has stunned scientists by its massive size and complex ongoing formation over tens of millions of years. This “lost continent” covers an area larger than Idaho and its origins stretch back to the age of dinosaurs.
Massive Undersea Plateau Larger Than Idaho Discovered
Scientists were amazed to discover an undersea plateau spanning over 1,240 miles across the seafloor, making it larger than the state of Idaho . This structure, known as the Melanesian Border Plateau (MBP), has been slowly forming over tens of millions of years through ongoing volcanic eruptions that have built up a giant superstructure on the seafloor north of Fiji.
“It’s quite remarkable that such a large structure like that has been growing since the age of dinosaurs and we didn’t even know it was there,” said geologist Jo Whittaker from the University of Tasmania .
Researchers were unaware of the true scale of this lost underwater continent until a recent ocean mapping survey combined with geological sampling revealed the MBP’s full expanse and ongoing expansion .
|Over 1.24 million square km, larger than Idaho
|Over 2,000 km long
|1-3 km tall from seafloor
|Formed over past 65-79 million years
This mammoth structure is composed of thick layers of solidified lava and other igneous rock that has accumulated to heights of 1-3 km above the seafloor. It represents one of Earth’s largest volcanic accumulations from a single region over such an extended period of time .
Origins Stretch Back to Dinosaur Age
Astoundingly, the initial formation of the Melanesian Border Plateau coincided with the extinction of the dinosaurs about 65 million years ago. Geological analysis shows that the northeast corner of the plateau originated 79-65 million years ago, meaning this superstructure has been growing since the Late Cretaceous period when T-rex still walked the Earth .
“It’s quite remarkable that such a large structure like that has been growing since the age of dinosaurs and we didn’t even know it was there,” explained geologist Jo Whittaker .
The plateau then expanded south and west over millions of years through episodic volcanic eruptions. This ongoing growth has formed a continuous subsurface ridge structure along the northeast coast of Australia that stretches over 2,000 km across the seafloor .
Ongoing Expansion Through Undersea Volcanic Activity
Contrary to initial beliefs that the plateau stopped developing over 10 million years ago, new evidence shows the eastern part of the structure is still actively growing through contemporary underwater volcanic activity .
“The eastern plateau is still very active and fuelled by the world’s fastest moving tectonic boundary,” said geophysicist Syracuse University’s Scott Bryan. This indicates that the ongoing collision of tectonic plates in the region is driving continuing eruption of lava that expands the plateau .
Further mapping revealed the MBP has a shallow eastern plateau that shows evidence of recent submarine volcanism. Meanwhile the western plateau portion stopped developing earlier but contains ridges, seamounts and many guyots – drowned volcanic islands eroded flat by waves .
This mix of old and new volcanism makes the MBP an intriguing case study for analyzing the complex life cycle of massive geomagnetic structures over tens of millions of years.
A Multi-Stage Formation Still Being Unraveled
Early assumptions were that the plateau formed from a single large igneous province spewing huge lava flows. However evidence now shows at least six separate volcanic clusters contributed to building the superstructure over multiple epochs .
“The plateau seems to have been built in distinct stages, rather than being the product of any one volcanic event,” explained geophysicist Kate Selway from Macquarie University in Sydney, Australia .
This multistage model corresponds to periodic mantle plume activity rather than a single hotspot, which better explains the intermittent nature of volcanism in the region. Each eruption phase coincided with movement of the Australian tectonic plate over different mantle plume locations .
Unraveling this intricate formation history helps explain the sheer scale and geological complexity of this previously little-known undersea continent.
Impact on Ocean Habitats and Climate
The abundance of guyots on the plateau provide foundations for fragile deep ocean reef systems in the otherwise mostly uninhabitable abyssal zone 200+ meters below the surface. These unique oases allow coral communities to develop that attract marine life across all ocean depths .
Undersea volcanic particulates also seed the ocean surface with iron vital for plankton growth. These phytoplankton capture large amounts of CO2 through photosynthesis, making submarine volcanoes important regulators of atmospheric carbon over millions of years .
Studying the plateau’s complex evolutionary pathways and associated ecological communities advances scientific knowledge about deep sea habitats, biodiversity, and even historic climate shifts.
Outlook for Further Discoveries
The unprecedented detail provided by modern seafloor mapping technology has brought the Melanesian Border Plateau into clearer focus, yet many mysteries remain about its full scale, formative processes, and environmental impact over tens of millions of years of expansion .
“It’s cleaned up our fuzzy view, but there is more exploration needed to help resolve the fine details,” said geologist Jo Whittaker .
Uncovering connections between plateau volcanism and historic changes in biodiversity, extinction events, ocean chemistry, and even shifts in Earth’s climate over the eons offers pathways for exciting research in years ahead. Each new revelation about this underwater behemoth provides another vital clue for analyzing our planet’s geological biography.
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