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Speaker: Dallas Sherman, Postdoctoral Research Fellow, University of Texas Institute for Geophysics

Host: Eric Attias

Title: Geophysics in Sustainable Resource Development and Hazard Assessment: A Focus on Marine Electromagnetics

Abstract: Geophysics has an increasingly important role to play in developing resources and assessing hazards for a sustainable future. This talk will present select case studies highlighting the use of geophysics in general, and marine electrogmagnetics in specific, to this end.

As the clean energy transition gains momentum, the demand for rare earth minerals has driven industry to seek deposits with increased logistical difficulties. Geophysics is a key component in not only quantifying the ore body, but also in guiding infrastructure development, as demonstrated by exploration in remote northern British Columbia and Greenland.

Developments in marine electromagnetics has allowed for near-shore surveys in support of discovery and management of offshore fresh ground water reservoirs and assessment of relict permafrost conditions. A surface-towed controlled-source electromagnetic (CSEM) system used offshore Hawaii identified a new mechanism for fresh groundwater discharge, as well as the presence of freshwater plumes and a large offshore fresh groundwater reservoir. The same surface-towed system successfully mapped subsea ice-bearing permafrost on the Beaufort Shelf along 200~km of coastline, an important step in quantifying the climate change hazard posed by relict permafrost and its associated methane hydrate. Maps of depth to permafrost and its thickness were produced from electrical resistivity inversions. This system provides a cost effective method that could be used to further quantify permafrost extent, provide a baseline for measurements of future degradation, and provide observational constraints to aid in permafrost modeling studies.

Mikayla Pascual, mikayla.pascual@utexas.edu

The UTIG Discussion Hour hosts weekly talks Wednesday afternoons at 2 pm CST. The Discussion Hour is a flexible format seminar hosted by UTIG and open to all members of our community. Presentations range from spotlighting new geoscience research to less technical talks sharing fieldwork excursions.

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Contact costa@ig.utexas.edu.

Speaker: Xinting Yu, Assistant Professor in Physics Astronomy, The University of Texas at San Antonio

Host: Krista Soderlund

Title: Deciphering the Nature of Titan’s Mysterious Magic Islands: The Role of Simple Organics

Abstract: In the ever-expanding world of planetary science, Titan, Saturn’s largest moon, stands as a realm filled with perplexing phenomena. One of the most enigmatic features is the so-called “magic islands” that appear and disappear on Titan’s liquid methane and ethane lakes. This talk will take you through a captivating investigation of how simple organics play a critical role in these ephemeral features. Building upon a comprehensive Titan material property database built by our group, this talk sheds light on the interactions between Titan’s atmospheric organic molecules and its lake liquids. The key focus will be on understanding whether these organic molecules float, sink, or do something entirely different once they make contact with the lakes.

Discover how atmospheric chemistry and thermophysical properties come together to unravel the fate of molecules like HCN, benzene, and ethylene when they hit Titan’s surface. Learn why some of these molecules may be responsible for Titan’s “magic islands,” while others find their resting place at the bottom of the lakes. By the end of this talk, you’ll gain insight into the complex interplay of atmospheric organic chemistry and planetary geology on Titan.

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Center for Planetary Systems Habitability Seminar Series.

Speaker: Sascha Grziwa, Research Associate, Rhenish Institute for Environmental Research, Department of Planetary Research, University of Cologne, Germany

Host: Brandon Jones

Title: The upcoming hunt for exoplanets in the habitable zone: Advances in the detection of exoplanets in the context of the upcoming ESA space mission PLATO

Abstract: In recent years, thousands of exoplanets have been discovered, largely thanks to space missions such as Kepler and TESS. However, a significant number of these exoplanets possess relatively short orbital periods, ranging from 10-20 days, which are even more compact than that of Mercury, our innermost planet. This bias towards shorter orbits arises from the extended baselines required to detect exoplanets with more extended orbits, both in space missions and subsequent follow-up observations. This leaves our understanding of stellar systems, their evolution, and statistics somewhat incomplete, as knowledge of exoplanets with larger orbital periods are needed for full characterization. One way forward is developing new techniques like the detection of mono-transits to uncover longer-period targets in existing photometric data. But finally, there is a need for space missions with extended baselines to provide a comprehensive catalogue of planets with wider orbits to complete the picture.

PLATO, an ESA mission slated for launch in 2026 will primarily focus to monitor bright stars (m_v < 11) over several years, aiming primarily to detect Earth-like planets within the habitable zones of solar-type stars. In addition, the mission will observe more than 250,000 stars (m_v < 13) with the ambition of detecting up to 7,000 new exoplanets.

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Contact costa@ig.utexas.edu.

Speaker: Anieke Brombacher, Postdoctoral Associate, Yale University

Host: Chris Lowery

Title: From individual life-history to species evolution: a case study with planktonic foraminifera

Abstract: Variation among individuals forms the raw material for evolution. During their lifetime, individuals can often adjust their state in response to environmental conditions. This plasticity in developmental history is hypothesized to stimulate the expression of novel trait combinations, increasing mean population fitness and accelerating local adaptation. However, very few empirical data exist to test this hypothesis on macroevolutionary time scales, as developmental history is often impossible to reconstruct from fossilized remains.

I use the exceptionally rich fossil record of planktonic foraminifera to study ontogenetic shifts in deep time. Foraminifera retain their entire life history inside their calcium carbonate shells, allowing for detailed morphometric analyses at different ontogenetic stages. Using morphological changes before, during and after speciation in the Menardella limbata – Menardella exilis – Menardella pertenuis lineage I studied changes to the timing of developmental processes. Using micro-CT scans, I plot individual chamber coordinates in xyz-space and reconstruct 3-dimensional growth trajectories with a new custom-made R package, Foram3D. The package functions calculate distances and angles between subsequent chambers, quantify trochospirality and reconstruct “Raupian” coiling parameters at every growth stage, and determine the number of chambers per whorl at the time each chamber was built.

The resulting developmental trajectories show that three-dimensional growth varies among species from the neanic and adult stage onwards. The angles between subsequent chambers increase after a species-specific size threshold is crossed, resulting in an increase in chambers in the final whorl and reduced chamber growth rates. Similarly, trochospirality (‘steepness’ of the shell spire) decreases at different chamber numbers among species, resulting in species-specific adult shell shapes. These results suggest that ontogenetic constraints can be overcome, resulting in novel morphologies and the emergence of new species.

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Contact costa@ig.utexas.edu.

Speaker: Alice Turner, Postdoctoral Fellow, University of Texas Institute for Geophysics

Host: Sean Gulick

Title: Lunar tectonics – insights from deep and shallow moonquakes

Abstract: During the 7-year operation of the Apollo seismic network, researchers detected and cataloged tens of thousands of seismic signals. This included signals from impacts, as well as shallow and deep moonquakes. The lunar seismic activity detected by these instruments, which are over 50 years old, still offers valuable information about the moon’s tectonics and dynamics. In this talk, split into two parts, I will discuss my work to unravel some of the puzzles of deep and shallow moonquakes.

Firstly, I will focus on deep repeating moonquakes. Deep moonquakes occur in clusters at 700–1,200-km depth and provide unique insight into the stresses deep in the lunar interior. Using observations of deep moonquake waveforms, I find tidal stresses to be the main driver of deep moonquakes. Based on these results, I intend to discuss the potential implications for lunar structure and the mechanism of deep moonquakes.

Secondly, I will focus on my recent work here at UTIG on shallow moonquakes. Classifying seismic signals correctly is key for evaluating the moon’s impact and seismicity rates. Yet, 60% of the original Nakamura et al. (1981) catalog events remain unclassified because the highly scattered lunar waveforms appear visually similar. In this work, we have developed a precise and quantitative method to distinguish between shallow moonquakes and impacts. Our preliminary results identify six features that differ between shallow moonquakes and impacts and suggest we may robustly and semi-automatically classify new or previously unclassified events.

Finally, I present my current and future research directions.