A huge geological superstructure lying deep beneath the surface of the Pacific Ocean has been growing since the Cretaceous period, facilitated by an area of intraplate volcanism larger than the United Kingdom.
In a new study, geologists attempt to piece together how the so-called Melanesian border plateau formed through several different pulses of volcanic activity that began when dinosaurs roamed the earth and continues to the present day. It was concluded that it was formed.
The ocean floor is dotted with countless seamounts, ocean ridges, and large volcanic structures. Such underwater features are often thought to be formed by a single, somewhat sudden volcanic disturbance. These events can be catastrophic, causing major environmental changes.
However, this recent study suggests that the Melanesian Border Plateau has a more complex background. This so-called superstructure, located in the southwestern Pacific Ocean, appears to have formed over millions of years through a slow-burning origin that unfolded in four distinct stages.
“The Pacific Basin has several characteristics. [scientists] “We only have one sample, and it looks like a very large, single event,” said study leader Kevin Conrad, an assistant professor at the University of Nevada, Las Vegas. live science.
“Sometimes, when we sample these features in detail, we find that they have actually been built over multiple pulses over tens of millions of years and have no significant impact on the environment,” Conrad continued. Ta.
To arrive at this discovery, the research team conducted geochemical analyzes of samples taken from the Melanesian Border Plateau region, Western Samoa Seamounts, Eastern Samoa Seamount Province, and the Tuvalu Seamount Chain region.
This showed that the origin of the superstructure began about 120 million years ago during the Cretaceous period with a huge eruption of lava that formed a series of seamounts.
In the second phase, from 56 million to 33.9 million years ago, the lithosphere (Earth’s outer rocky shell) passed over a volcanic region called the Arago hotspot, creating more seamounts and several oceanic islands. was formed. These islands eventually eroded and sank below the earth’s surface.
Third, fast forward to the more recent Miocene (23 million to 5 million years ago). When the Earth’s lithosphere passed over another hotspot, the Samoa Hotspot, the same islands and undersea mountains reactivated and new volcanoes formed. This volcanic hotspot is still creating new islands.
Finally, during this ongoing period, new volcanic eruptions occurred on the plateau as the lithosphere was deformed by the unrolling of the Pacific plate beneath the Tonga Trench.
It’s a complex story, and researchers say it could provide a more nuanced picture of how underwater features form. To describe the geological products of these multi-step events, the research team proposes the term “mid-oceanic plate superstructure.”
New research published in journals Earth and Planetary Science Letters.
[H/T: Live Science]