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Fieldwork in Namibia on ancient volcanic rocks

9/15/16

by: Andrea Stafford, digital content/marketing coordinator

During the summer Richard Hanson, who holds the Harold D. and Imogene Herndon Professorship in Geology, traveled to Namibia with a group graduate students to continue long-term research on tectonic evolution of volcanic processes on parts of the African continent.

“The rocks we are studying are between 1.1 and 1.4 billion years old, and they should provide important insights into the tectonics of the region,” Hanson said.

Dave and John

Baylor (left) and Williams (right) standing in the rugged desert landscape (photo by Katelyn Lehman ’14)

During the six-week trip in southwest Namibia, the research team conducted two projects. One involved mapping and producing detailed outcrop studies to determine eruptive processes that formed the variety of volcanic rock. The other research project involved collecting samples for geochemical studies, which will be analyzed for a variety of major and trace elements and isotopes. The analysis will provide information about ancient plate-tectonic settings, and this kind of detailed geochemical study on the volcanic terrain as a whole has not been attempted according to Hanson.

The four student researchers worked independently and collaboratively to examine the volcanic terrain. Virginia Andrews ’15 and Katelyn Lehman ’14 both studied geology as undergraduates at TCU, and both plan to base their master’s theses on parts of the volcanic terrain. David Baylor ’16 and John Williams served as field assistants on the trip. Like Andrews and Lehman, Williams is pursuing a master’s degree in in geology.

Lehman’s thesis research will focus on the geochemistry of the volcanic rocks, and she will work on the Namibian samples in laboratories at TCU and other institutions.

“It takes a lot of experience and patience to be a good field geologist, and you have to have an eye for details. Working with Hanson allowed me to gain additional experience in this, which is vital for geochemistry,” Lehman said. “Understanding the field relationships of a rock gives context to the geochemical data.”

truck in distance

“The volcanoes we were looking at are very old, and they help us to determine the processes that allowed the continents to come together to form the ancient supercontinent, Rodinia, about a billion years ago,” Lehman said. “We want to know the causes behind the volcanism within the region.”

Katelyn

Lehman is pictured surrounded by stark desert scenery (photo by Richard Hanson)

“By understanding and seeing different eruptive styles, we can work to reconstruct the environment of these volcanoes and the larger scale changes in the tectonic setting,” Lehman said. “It is fascinating to see how much happens in three hundred million years.”

Andrew’s thesis project is a modern, detailed volcanological investigation of the study area. “We discovered widespread volcanic deposits that were formed by eruptions similar to those that produce high fountains of lava spatter in Hawaii today,” she said.

The volcanism occurred in environments with abundant lakes, causing more explosive volcanic events when lava heated lake water to form steam, said Andrews. “We also discovered that we could see the magma plumbing systems that fed these volcanoes, which is generally not possible in modern environments.”

Andrews and Lehman will present initial results of their fieldwork in September at the annual meeting of the Geological Society of America conference in Denver.

 

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