Sharon Mosher Receives Alumni Achievement Award

Posted on 08.23.2015

Sharon Mosher, B.S. '73, Ph.D. '78, has been awarded the Geology Department's Alumni Achievement Award for 2001. Mosher, Wilton Scott Centennial Professor of structural geology at the University of Texas, Austin, primarily studies past plate tectonic movement in order to understand similar processes today. In the course of her research she has done field work as close as Texas' Llano Uplift and as far away as Tierra del Fuego. Mosher also has been appointed president of the Geological Society of America.

For much of the last decade, Mosher has worked in the Precambrian of Texas, studying an ancient plate boundary. "About 1.26 billion years ago, a volcanic arc formed on the southern margin of the North American continent," says Mosher. Then much later, at about 1.05 billion years ago, an exotic island volcanic arc and another continent collided with North America forming a major mountain belt."

Most recently, Mosher and her students have been studying an active plate boundary between the Australian and Pacific plates. This area has a very complex deformation history. Mosher estimates that 40 million years ago this was a spreading plate boundary, with magma coming up to form new sea floor. At 33 million years the boundary began pulling apart obliquely and by about 10 million years ago the plates were moving almost parallel to each, making a transform fault. Today this boundary is one of the most active in the world; in 1989 the strongest earthquake ever measured (8.1 on the Richter scale) occurred along this boundary.

"This is the only place in the world with a record of both spreading plates and transform faults," says Mosher. Mosher's research will help her understand how rocks behave as they go from spreading to transform faulting; what chemical or mechanical properties influence the translation from one process to another; and whether the changes occurred sequentially or whether some occurred simultaneously. Ultimately, Mosher wants to understand the mechanisms behind changing from one type of plate boundary to another.

In addition, Mosher hopes to understand the processes involved when magmatism shuts off.

"We know a lot about spreading ridges, but we don't know much about how spreading stops," she says.

What Mosher learns about the behavior of this particular plate boundary she hopes to apply to other boundaries around the world.

Mosher and her students also have been able to conduct field investigations on a tiny island, Macquerie (ma-qwair-EE), which is on the boundary between the Australian and Pacific plates. The island, which is about 4 km wide and 34 km long, is about halfway between Antarctica and New Zealand. A piece of rock jutting out from the boundary got lifted up as the plates slid past each other, creating Macquerie. The island is part of the ocean floor that was uplifted and preserved. Macquerie is home to millions of penguins and about 100,000 elephant seals ... and not much else. In fact, Mosher estimates that only about one dozen geologists have ever made it to the island. She and her students were the first non-New Zealanders and the first structural geologists to visit the island.

"We can use the geology of the island to field check our marine geophysical data," says Mosher. "You can see great geology on the island. There are sea mounts, lava hills and fault topography, all of which are cut by faults that occurred in our lifetime."

In addition to these research activities and teaching responsibilities, Mosher has taken on the presidency of the Geological Society of America (GSA). Mosher had previously served as vice president of GSA where she became involved in finding ways for members to become more effective in influencing public policy. Prior to this role, Mosher served three years as annual program chair and oversaw the reorganization of the Annual Meeting program.

As president, Mosher envisions GSA working to help members become more effective at influencing public policy, to facilitate the interaction of scientists across disciplines, and to join forces with other geoscience societies to concentrate resources when addressing similar problems and goals.

"GSA has the potential to make an impact in professional development, public outreach and public policy," asserts Mosher.