South of California and on Mexico’s west coast sits Baja California, a thin peninsula that broke apart from its mainland millions of years ago. Until recently, geologists knew how it was formed, but had no idea quite how far away those processes began.
Researchers in the Jackson School of Geosciences published a study hypothesizing that tectonic activity in the Western Pacific near Japan affected the Gulf of California’s formation around 10 million years ago.
Two of the four authors of the Oct. 29 Science article come from UT: Xiang He, a graduate student in the Jackson School, and Thorsten Becker, a distinguished chair in geophysics and a professor.
The Gulf of California is a sea between Baja California and northern Mexico. It started to form from continental rifting — where a continent gradually breaks apart into pieces — before tectonic activity around Japan’s plates occurred, He, who worked on the study’s numerical modeling, said. However, the specifics of how this gulf continued to form could not be explained by just the small region around the peninsula. Becker and He decided to look for an answer across the ocean.
“Some geologists focus mainly on the local parts,” He said. “They look for some evidence around the Gulf of California to see what kind of forces are driving it, but (Becker) noticed we should look for another driving force on the other side of the world instead of focusing around North America.”
He and Becker said that, according to their findings, around 10 million years ago a double subduction zone appeared in the western Pacific Ocean. Unlike a single subduction zone, where one plate goes under another, a double subduction zone involves two plates rubbing against the same plate at once, according to a Jackson School press release about the study. Rifting at the gulf was increasing at the same time.
He said the amount of force from a double subduction event would have sped up the gulf’s rifting and created the peninsula.
Becker and He worked with the Texas Advanced Computing Center to have the geophysical modeling capability for the project, which required more advanced work with supercomputers. They said working with the other researchers from the Czech Republic and Italy has been a great learning opportunity at the University.
“UT is a fantastic place to do interdisciplinary research,” Becker said. “That’s something that we’re quite good at here.”
