The Louisiade Plateau, also called the Louisiade Rise, is a poorly studied

oceanic plateau An oceanic or submarine plateau is a large, relatively flat elevation that is higher than the surrounding relief with one or more relatively steep sides. There are 184 oceanic plateaus in the world, covering an area of or about 5.11% of the ...

in the northern

Coral Sea The Coral Sea () is a marginal sea of the South Pacific off the northeast coast of Australia, and classified as an interim Australian bioregion. The Coral Sea extends down the Australian northeast coast. Most of it is protected by the Fre ...

of the

South Pacific Ocean South is one of the cardinal directions or compass points. The direction is the opposite of north and is perpendicular to both east and west. Etymology The word ''south'' comes from Old English ''sūþ'', from earlier Proto-Germanic ''*sunþaz ...

. To its west is the

Louisiade Archipelago The Louisiade Archipelago is a string of ten larger volcanic islands frequently fringed by coral reefs, and 90 smaller coral islands in Papua New Guinea. It is located 200 km southeast of New Guinea, stretching over more than and spread ...

that it is named after. It has been described as a

continental fragment Continental crustal fragments, partly synonymous with microcontinents, are pieces of continents that have broken off from main continental masses to form distinct islands that are often several hundred kilometers from their place of origin. Caus ...

that

rift In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Typical rift features are a central linear downfaulted depression, called a graben, or more commonly a half-grabe ...

ed away from the northwestern

continental margin A continental margin is the outer edge of continental crust abutting oceanic crust under coastal waters. It is one of the three major zones of the ocean floor, the other two being deep-ocean basins and mid-ocean ridges. The continental margin ...

of Australia but its position at the northern end of the

Tasmantid Seamount Chain The Tasmantid Seamount Chain is a long chain of seamounts in the South Pacific Ocean. The chain consists of over 16 extinct volcanic peaks, many rising more than from the seabed. It is one of the two parallel seamount chains alongside the Ea ...

also suggests that the Louisiade Plateau might be a

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...

formed by the arrival of the

Tasmantid hotspot The Tasmantid hotspot is a volcanic hotspot located in the South Pacific Ocean. Due to plate tectonics the hotspot was under different parts of the seabed in the past. It was initially centred under what is now the southern Coral Sea 60 mil ...

. A sample of volcanic rock from the southern spur of the Louisiade Plateau was dated at 56.4 ± 0.6 million years ago by Ar-Ar methodology which is not inconsistent with

timings. Recent sampling however along the northernmost part of the plateau found serpentinized peridotites,

mid-ocean ridge A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diverge ...

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

and volcaniclastic breccia–conglomerates consistent with placement of oceanic crust during a

subduction Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

initiation event in the formation of this part of the plateau.

References

{{reflist Plateaus of the Pacific Ocean Coral Sea