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Research Professor, Institute for Geophysics, Jackson School of Geosciences
nathan@ig.utexas.edu
+1 512 471 0424

Expertise: Structural development and tectonic processes along convergent margins; MCS methods to acquire 3-D images of structure and stratigraphy within subduction zones; processing, inversion, and modeling of seismic reflection data

Associate Professor, Department of Earth and Planetary Sciences, Jackson School of Geosciences
ejcatlos@jsg.utexas.edu
+1 512 471 4762

Expertise: Can also see https://www.catlos.work/ My primary research focus is geochemistry, and how the fundamentals of chemistry (mineral reactions, radiogenic and stable isotopes, major and trace elements) can be and are used to understand what the Earth was like in the past. In this, I have interests that span a broad range of range of plate boundary processes and laboratory approaches. Many ancient fault systems are clues to determine the evolution and migration of Earth's continents in the past, identify important economic resources that formed during specific times in Earth's history, and/or to assess geological hazards that result due to reactivation of older faults or mass movement of rocks. They are used to understand how plate tectonics operates today and how it operated in the past. I am interested in constraining the evolution of a number of fault systems and mountain ranges that formed during the closure of ancient ocean systems primarily across Asia, the Middle East, and Europe. For example, a major portion of my Himalayan research agenda involves constraining past motion on the Main Central Thrust, a large-scale shear zone that worked to create the highest mountains on the planet. I currently use novel geochemical and geochronological approaches that take advantage of modern-day technology to understand how garnet-bearing rocks moved at a high-resolution scale within that structure. Garnets are chemical tape recorders, and their chemical elements can be used to ascertain the pressures and temperatures they experienced. They also enclose radioactive minerals, such as monazite, that can be dated to time their history. Data from numerous garnet-bearing rocks across the Main Central Thrust can be used to inform us regarding how and when the Himalayas uplifted in the past, and lend insight into the motion that affects it today. To this end, I collaborate and learn from other researchers, such as geophysicists and modelers. I apply similar approaches to garnet-bearing rocks found in extensional systems in western Turkey. In this region, the plate boundary experienced a major switch in the geological past from compression to extension. Again, I apply new approaches in the thermodynamic modeling and geochronology to garnets in this locale to understand why and how this plate tectonic transition occurred. In this portion of my research, I also include the study of granites, as these igneous bodies emplaced during the extensional phase. The timing of their formation is key pieces of information regarding how extension occurred in western Turkey, both in time and space. To this end, I pioneered new imaging approaches to their study, and collaborate with economic geologists in Turkey who are interested in how heat and fluid flow around these granite bodies are intricately involved in the formation of ore resources. Their research sparked my interest in granite petrology, and I also study this rock type in China and Slovakia. Some of these granites formed at ancient plate boundaries as continents collided, and their ages and chemistry constrain when and what types of geological processes operated during their formation. The approaches I apply (geochemistry and geochronology) are of interest to a wide variety of researchers, so I collaborate and involve students in projects that include other geologists. An example of this is the dating of radioactive minerals from ancient meteorite impact craters and massive volcanic eruptions, events that are key for shaping how life evolved in Earth's history. These projects involve the use of modern and ever-evolving technological advances in geochemistry, such as the laser ablation of tiny zircon crystals, or the use of instruments that do not require minerals to be separated from rocks, such as secondary ion mass spectrometry (SIMS). I am interested in accessory minerals, such as zircon and monazite, and what controls their appearance in metamorphic and igneous rocks. Monazite, in particular, has been a focus of my research and I have key expertise in its formation, composition, geochronology, and its use as a rare earth resource. Although my research primarily involves compressional and extensional plate boundaries and igneous and metamorphic rocks, I recently delved into understanding sedimentary rocks from along the North Anatolian Fault, a major strike-slip system in north-central Turkey. In this research, we obtained oxygen isotopes across transects along calcite-filled fractures in limestones using SIMS. These calcite-filled fractures have the potential to record their source and provide key insight into the history of the limestones as well as their use for recording modern day fluid flow driven by seismic activity along the active fault system. Fundamentally, my research is field-based and involves the mapping and collection of rocks and understanding their importance in addressing research questions regarding what the Earth was like in the past. The research is laboratory-based, and I take advantage of modern advances in technology applied to geosciences, including numerous facilities at UT Austin and elsewhere.

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