Running for hundreds of miles along the northeastern edge of the Pacific region of Melanesia, Melanesian border plateau It is a geological graveyard of dead coral reefs and collapsed islands.
This feature is one of a myriad of formations known as. large igneous area. Such geological superstructures are usually the result of massive amounts of rock bled out from the endless sliding and crushing of oceanic plate tectonics.
However, details about the origin of the Melanesian Border Plateau (MBP) have long been lacking. A study by an international research team led by University of Nevada geoscientist Kevin Conrad has revealed important evidence for the formation of MBPs. This could help us better understand the forces shaping the Earth as a whole.
The area of the superstructure is approximately 222,000 square kilometers (85,000 square miles), slightly smaller than the area of Great Britain.
Just skimming material from its surface is enough to show that the plateau is igneous in nature, with the bones of the rock dating back to normal Cretaceous periods some 122 million to 83 million years ago. It is composed of cooled magma released sometime during the Superchron period.
But mining evidence from the ocean floor isn’t as easy as searching for clues on land. The rare minerals dredged over time suggest that MBP’s origin was not simple and that there were at least 25 different volcanic structures in its formation.
If this plateau had been formed by a single large-scale magma flood, the environmental impact would have been severe. So learning more about this volcanic structure’s steady growth could help us better understand everything from climate change to past extinction events.
To discover how the jigsaw puzzle pieces of the surrounding trench and plateau interacted over time to form the MBP, Conrad and his team used cognate samples taken from the plateau and surrounding geological formations. Previously published data on body ratios and other forms of geochemistry were used to model MBP progression. Earth’s crust as it passes over a hot plume in the mantle.
These intense fountains of heat rise, known as hotspots, remain relatively stationary even as the Earth’s crust gradually moves across. As a result, columns of blistering magma break through weak points in the rock, forming traces of volcanic activity and splattering the sunken walls of island chains, mountain ridges, and seamounts.
When you put the pieces together, Louisville hotspots Somewhere in the South Pacific, the foundations of the MBP were laid some 120 million years ago, when dinosaurs still ruled, and a torrent of magma oozed over what is now known as Robbie Ridge and several other surrounding areas. formed seamounts.
About 45 million years later, the same weakened section of the Earth’s crust met a second region known as the “crust.” Rurutu Arago hotspots, we saw the emergence of new islands and seamounts. Over time, these are pulled back deeper, but their roots contribute to the structure of the plateau.
3rd hotspot The cause of the present-day Samoan archipelago would have been the resumption of seamount and island formation and new volcanic activity about 20 million years ago.
To this day, the enormous forces deforming the Earth’s crust are provided in part by the unwinding of the Pacific plate beneath the Tonga Trench, a process that illustrates how complex the formation of large igneous provinces is. continues to form a superstructure.
The research team refers to these hypothetical crustal “undulations” as oceanic central plate superstructures.
Knowing that just one such superstructure can emerge in pulses as weakened crust sails through a storm anchored in the mantle means that other structures may also Suggesting that it may have formed in a similar way, building slowly and quietly rather than in a cataclysmic eruption.
Finding them will require a new voyage of discovery, sampling the midnight depths for other traces of Earth’s hotspots scarring the surface.
This research Earth and Planetary Science Letters.