Tracking Ancient Mantle Movement

Dr. Anthony Koppers

Dr. Anthony Koppers

Dr. Anthony Koppers of Oregon State University visited the Brigham Young University Department of Geological Sciences on April 15 as a part of the International Ocean Discovery Program (IODP) Distinguished Lecture Series. His lecture was titled, “Drilling Hotspots to Unravel the Mantle Wind.”

Koppers is currently a professor of marine geology at Oregon State University (OSU) and a research associate at the Scripps Institute of Oceanography. He has a PhD in plate tectonics and mantle geochemistry from Vrije Universiteit in Amsterdam.

His current research is focused on studying large-scale mantle movement called “mantle wind.” In previous research studying the trails of volcanic centers called “hotspots,” IODP researchers found that the hotspot, which created the Hawaiian Islands and its associated seamounts had moved southward by almost fifteen degrees between eighty and fifty million years ago. This was surprising because hotspots were thought to be fairly stationary plumes of “warm rock” rising slowly from the boundary of the Earth’s core and mantle to its surface.

The discovered movement could be the result of such a “mantle wind” and Koppers’s research team wanted to discover whether the same wind had affected other hotspots in the Pacific Ocean as well.

“We ask really good questions that can only be answered by drilling . . . and then we go out and find the answers,” Koppers said.

To answer this particular question, Koppers and his research team decided to drill into a hotspot in the South Pacific, called the Louisville hotspot. After taking samples of the site’s basalt, Koppers’s team measured the magnetic properties of the rocks aboard the ocean drilling research ship, the JOIDES Resolution, and they age-dated the samples in Koppers’s OSU Argon Geochronology Lab. Specially designed for scientific research, this ship allows researchers to analyze their findings without having to wait for the expedition to be over.

“It’s like having a lab in the ocean,” Koppers said.

Comparing samples from several sites along the Louisville hotspot track, the team found that it had moved three to five degrees between eighty and fifty million years ago, compared to the Hawaiian hotspot, which moved fifteen degrees. Based on these findings, Koppers and his team concluded that hotspots are neither stationary, nor linked directly to each other, but move independently according to a “local mantle wind.”

This research was a part of the new International Ocean Discovery Program that is “Exploring the Earth Under the Sea,” which began in October 2013. The IODP Distinguished Lecture Series has made possible over 750 presentations to US colleges, universities, and other organizations since 1991.

By Meg Monk Posted on