Welcome! I am a geologist who uses geochemistry, geochronology, and petrology to understand the history of Earth's lithosphere. For example: how does the chemical evolution of continental crust reflect planetary-scale Earth changes? Why and how do new subduction zones break, and how do they reach steady state? What is the composition of modern lower crust, and what role does it play in keeping continents stable over the long term?
My approach to these questions involves field work in modern and ancient mountain belts, followed by high-precision analytical and modelling work. This includes "geochemical signal processing": using statistical tools (PCA, ICA, cluster analysis) to isolate distinct trends from large geochemical datasets, including those I collect (e.g., by LA-ICPMS) or from compiled data (e.g., GEOROC). I also use novel, high-resolution laser-ablation techniques to understand rock thermal and chemical histories from single crystals. Recently, I have combined these approaches with geophysical data to understand the composition and thermal state of cratonic mantle lithosphere.
I am currently a postdoctoral scholar and LA-ICPMS laboratory manager at Penn State, working closely with Drs. Andy Smye, Jesse Reimink, and Maureen Feineman. [You can read about our lab here.] Pennsylvania has a rich natural and cultural history, and in my spare time, you can find me investigating local geology, hikes, birds, and mushrooms.
Please feel free to reach out and discuss anything you see here at jmgarber [at] psu [dot] edu.