Cathleen Doherty
The dynamic nature of Earth has always amazed me. I find it fascinating that a single rock has the ability to preserve geochemical imprints over billions of years, and with that it also preserve a history of Earth’s dynamic interior. Radiogenic isotopes are important tools (geochemical imprints) that allow us to peer into the otherwise inaccessible interior of our planet, enabling us to identify and characterize deep Earth reservoirs. I am especially interested in using modern analytical techniques to measure Sr-Nd-Hf-Os-He isotopes in order to unravel the Earth’s history. I am also interested the broad applications of radiogenic isotopes (e.g. sediment provenance, mantle evolution, origins of igneous rocks) and ability to use a single isotope system to answer a multitude of questions.
My current research involves using a suite of analytical techniques to investigate the geochemical and dynamic evolution of the subcontinental lithospheric mantle (SCLM) beneath the West Antarctic Rift System. More specifically, I’m studying mantle xenoliths using the Re-Os isotope system to constrain ages of melt depletion and subsequent stabilization of the SCLM. Re-Os isotope data correlated with major element melt extraction indices allows us to better constrain and understand major melt depletion events recorded in the SCLM. Using this age information, we can map the lithospheric mantle boundaries across a rifted margin and test for models of rifting. The next step in this study is to use Sr-Nd-Hf-He isotopes systems and trace elements to investigate the role of the SCLM in the formation of regional volcanics, look for evidence of metasomatic re-enrichment after melt depletion, and determine the possibility of mantle plume activity. From this, I hope to gain a better understanding of the mantle’s role in continent formation, and how it records geochemical differentiation events in a tectonically complex region.
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