Earth scientist Dasgupta lands NSF CAREER Award

Rice University Earth scientist Rajdeep Dasgupta has won a prestigious National Science Foundation (NSF) CAREER Award to unearth new details about processes and chemistry happening deep underground.

Rajdeep Dasgupta won an NSF CAREER Award to pursue his investigation of deep-Earth chemistry. Photo by Jeff Fitlow

The five-year grant, which goes to young scientists expected to have significant impact on their fields of study, will support a comprehensive look into the chemical evolution of Earth’s interior. Dasgupta and his team will focus on how processes in Earth’s mantle affect surface rock that dips downward over millions of years and how that surface rock interacts with the dense, coarse igneous rock called peridotite that makes up the bulk of material there.

“In this project, we’re looking at reactive processes in the interior of our planet,” said Dasgupta, an assistant professor of Earth science. “Earth runs a cycle. Surface rocks and sediments go down into the mantle; the mantle partially melts and produces magma that erupts in hotspots like Hawaii and Iceland. It produces new crust that will eventually go back down into the mantle.”

Subduction-and-volcanic eruption cycles, the result of Earth’s unique plate tectonics, are key to keeping the surface world chemically diverse, he said. But there’s still much to be learned about the processes happening tens to hundreds of miles down.

In ongoing research, Dasgupta and his team obtain rock believed to be present in the mantle — and representative of what’s still there — and subject it to pressures and temperatures capable of liquefying it in tiny amounts. That tells them a great deal about the conditions necessary to drive the cycle.

“But one thing has not been looked at systematically enough,” he said. “We argue that while there’s a dominant type of rock in the mantle, peridotite, there are also small amounts of crustal rocks that go down through plate tectonic cycles. When these rocks participate in the mantle convection, they also melt and react chemically with the dominant rock in a process we call magma-rock reaction or hybridization. It basically must create new types of rock and at the same time produce magma of different composition.”

“Our current understanding of the process of partial melting and magma eruption is far more simplistic than what is actually happening,” he said.

Dasgupta said the project grew from the ongoing research of Ananya Mallik, a fourth-year graduate student in his lab. “She started looking at melt-rock reactions and hybridization from the beginning of her time here and had a lot of input into the proposal,” he said. “Exciting results from Ananya’s initial experiments allowed me to develop this into a much bigger, more ambitious project.

“We have a pretty wide depth, temperature and compositional window to map out in terms of reactive processes in the convective mantle,” he said. “This project is more ambitious than what I can defend in a standard two- or three-year NSF grant. Perhaps it’s ambitious even for a five-year project, but we’re grateful for the opportunity.”

The grant will also give Dasgupta the resources to bring in students from underrepresented groups from local community colleges for summer internships in his lab.

With this CAREER Award, Dasgupta’s profile as a researcher and educator continues to rise. He received the Hisashi Kuno Award from the American Geophysical Union in December. A January paper in Nature on how deep magma forms in the mantle brought attention, and earlier this month he participated in a panel discussion at the Deep Carbon Observatory’s international meeting at the National Academy of Sciences in Washington, D.C., and contributed a chapter to the organization’s massive “Carbon in Earth” study.