[Rockhounds] 'Superstructure' bigger than Idaho has been growing on the seafloor by Fiji since the dinosaur age

[Kreigh Tomaszewski]

An undersea plateau in the Pacific Ocean that is bigger than Idaho first
started forming with volcanic eruptions during the *Cretaceous period*
<https://www.livescience.com/29231-cretaceous-period.html> (145 to 66
million years ago), and it is still growing today.

In fact, the Melanesian Border Plateau, located east of the Solomon
Islands, formed through four separate pulses of volcanism, all with
different root causes, according to new research published Jan. 15 in the
journal *Earth and Planetary Science Letters*
<https://www.sciencedirect.com/science/article/abs/pii/S0012821X23005605>.

This timeline is important, because giant volcanic features under the ocean
are often poorly understood,  said study leader *Kevin Konrad*
<https://geoscience.unlv.edu/kevin-konrad/>, a geoscientist at the
University of Nevada, Las Vegas. In some cases, they form in a single flood
of magma, in which case they're known as large igneous provinces. These
huge, long-lasting volcanic events are so dramatic that they often shift
the climate and have been associated with mass extinctions.

But in other cases, features that look identical to large igneous provinces
are actually built over long periods, with multiple volcanic events piling
up rock like a layer cake. With limited rock samples, it can be hard to
tell the difference.

"There are some features in the Pacific basin where [scientists] have only
a single sample, and it looks like a very large massive single event,"
Konrad told Live Science. "Sometimes when we sample these features in
detail, we realize they're actually built over multiple pulses over tens of
millions of years and wouldn't have significant environmental impacts."

https://www.livescience.com/planet-earth/superstructure-bigger-than-idaho-has-been-growing-on-the-seafloor-by-fiji-since-the-dinosaur-age