Charu Garapaty

Earth Science

Using the Antarctic Rock Record to Better Understand Supercontinent Amalgamation 1.7 Billion Years Ago

Igneous and metamorphic rocks from the Transantarctic Mountains in Antarctica provide information about crust formation and supercontinent cycles over the past 3.1 billion years (Ga). Igneous rocks record crust formation and possible recycling of older crust. Metamorphic rocks record the tectonic history of the region. Antarctic geology enables analysis of how crust has evolved because it contains a continuous rock record of over 2.5 Ga. There are very few locations that can provide a continuous rock record that spans a large duration of Earth’s history. Studying igneous rock ages as well as metamorphic pressure and temperature conditions provides information about the East Antarctic Craton, which is mostly unexposed under the East Antarctic Ice Sheet. These craton rocks may provide insight into previous supercontinent formation of Rodinia, which can better our understanding of how crust formation has changed through time. By combining these rock records, we can reveal how the original crust formed and how continental crust forms supercontinents. The mineral zircon is highly resistant to alteration such as metamorphism, and records when igneous rocks form before any deformation. When preexisting rocks undergo metamorphism, the pressure and temperature conditions can be recorded in minerals that are not resistant to deformation such as monazite. Both zircon and monazite can be analyzed and dated using a mass spectrometer. This information can help us understand the metamorphic and igneous history of the past supercontinents. Results will determine when and where plate tectonics occurred at the Antarctic continent, possibly revealing how early plate tectonics initiated.

UC Santa Barbara Center for Science and Engineering Partnerships UCSB California NanoSystems Institute