Events

DeFord Lecture | Kristin Bergman

Towards a temperature record across the advent of complex life by Kristin Bergman, MIT

Abstract: The ecology and habitability of Earth is fundamentally shaped by its surface temperature. But, the further back in time we look, this history becomes increasingly difficult to reconstruct. This is particularly true over the ?4 billion years when microbes ruled and before animals like corals began making skeletons and shells out of seawater. Consequently, Earth’s temperature history in deep time is, and has been, the subject of a vigorous, decades-long debate.

In my work, we are developing multi-mineral isotopic and petrographic methods to understand the role of temperature, fluid chemistry, and diagenesis on two isotopic systems—oxygen isotopes and clumped isotopes—that reefs and other carbonates record as they grow. We are developing local records and present details of those alongside a new high-resolution record of bulk carbonate oxygen isotopes for the last billion years of Earth’s history.

My results suggest one solution to the previous ambiguity surrounding seawater oxygen isotope composition through time. Based on our results to date, and other distinctive features of our high resolution oxygen isotope record, we hypothesize that temperature, and not just atmospheric oxygen levels, was a key factor for understanding emergence, diversification and subsequent trajectory of complex life.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating DGS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

RoKafe

Faculty Meeting

DeFord Lecture | Renyi Zhang

Do industrial emissions play a role in the catastrophe during Hurricane Harvey? by Renyi Zhang, Texas A&M University

Abstract: Hurricane Harvey caused catastrophic flooding (about 555 mm in the Houston urban area) and more than 100 deaths during 25-27 August 2017. It is tied with 2005’s Hurricane Katrina as the costliest tropical cyclone on record, inflicting 5 billion in damage, primarily from catastrophic rainfall-triggered flooding in the Houston metropolitan area and Southeast Texas. Although several recent studies have linked Hurricane Harvey’s devastation to climate change or changes in land use due to urbanization, the cause of the catastrophic flooding remains uncertain. Tropical cyclones are driven by latent heat release from condensation and are inevitably linked to the abundance of aerosols by acting as cloud condensation nuclei. In this talk, I will present results from both measurements and numerical model simulations to investigate the impacts of anthropogenic aerosols on deep moist convection, precipitation, and lightning activities during hurricane Harvey. Our work shows a non-negligible effect of anthropogenic aerosols on this regional extreme weather event, highlighting the necessity of accounting for the aerosol effects in hurricane forecast models to accurately predict precipitation and to minimize the storm damage along the heavily industrialized Gulf of Mexico region.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating DGS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Liz Drenkard, GFDL NOAA

RoKafe

Faculty Meeting

Doctoral Defense | Nicholas Meszaros

The final doctoral examination for NICHOLAS MESZAROS has been scheduled for MARCH 22, 2023; 2:00PM; JGB 3.116 AND VIRTUAL.

The PhD project “Prelude To The Latest Caldera-Forming Eruption Of The Jemez Magmatic System, New Mexico, USA” was supervised by Dr. Jim Gardner.

Committee members include: Kenneth Befus, Richard A Ketcham, Jaime D Barnes, Matthew Zimmerer, Laura Waters

ZOOM link:  https://utexas.zoom.us/j/98837704980

The defense is open to all members of the University community and the public.

DeFord Lecture | Stephanie Pierce

Functional adaptive landscapes (help) illuminate major transitions in vertebrate evolution by Stephanie Pierce, Harvard University

Abstract: The concept of the adaptive landscape has been an invaluable tool to the field of modern evolutionary biology by providing a representation of how fitness and selection vary within populations of organisms. Trait variation can be visualized as a multidimensional “landscape” (analogous to a mountain range) with height on the landscape corresponding to fitness; selection acting on populations is expected to drive populations “up-hill” to cluster around “adaptive peaks” where fitness is maximized. Although originally implemented in the study of population genetics and microevolution, paleontologist G.G. Simpson expanded the idea of the adaptive landscape to explain phenotypic change over macroevolutionary timescales. Specifically, he linked large-scale biological and geological processes, such as extinction and climate change, with shifts in adaptive peaks representing selection acting upon phenotypic traits that were of “functional benefit”. Despite decades passed, the practical application of Simpson’s adaptive landscape in macroevolution has been limited by computational challenges in quantifying the functional performance outcomes of morphological traits and how they vary across a vast phenotypic landscape. Here I will introduce a new method called “functional adaptive landscape analysis” which determines the functional trade-offs associated with morphological adaptation to differing selection regimes. I will then use this method to explore two major transitions in vertebrate evolution. First, I will tackle the fish-to-tetrapod transition and the origin of land locomotion by modelling the evolution of the humerus bone. I will show that the earliest tetrapods occupied a performance valley between water and land adaptive peaks, but that adaptations suggest some capacity for terrestrial locomotion. Second, I will discuss the ‘reptile’-to-mammal transition and the evolution of the mammalian backbone. Using vertebral morphometric data and experimental biomechanics, I will test the lateral-sagittal functional paradigm and demonstrate how this long-held idea is too simplistic to explain mammalian backbone evolution. Together, I will establish the utility of functional adaptive landscapes in quantitatively testing longstanding questions in the vertebrate fossil record and its potential application to unravelling the relationship between form, function, and adaptation across deep time.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating DGS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Ben Phrampus, U.S. Naval Research Laboratory

Planetary Habitability Series: Katie Teixeira & Jialong Ren, UT Austin

TALK ONE

Speaker: Katie Teixeira, Graduate Student, Department of Astronomy, UT Austin College of Natural Sciences

Host: Brandon Jones

Title: Modeling the Evolution of Terrestrial Planet Atmospheres Through Outgassing and Escape

Abstract: With the successful deployment of JWST, and its aim to potentially search for biosignatures on exoplanets, an important endeavor, at present, is to determine whether the rocky planets we observe are likely to have atmospheres at all. M dwarfs, the main host stars of JWST’s rocky planet targets, are thought to pose a major threat to planetary atmospheres due to their high magnetic activity over several billion-year timescales, and might completely strip planets down to bare rocks. Physical models are necessary to understand how a planet’s atmosphere evolves to become what we see today. Here, I will present coupled time-dependent simulations of atmospheric escape and planetary outgassing, processes that most influence atmospheric size and composition. I will present a case study of TRAPPIST-1c, a possible “exo-Venus” for which observations have recently been taken. I will review the results of simulations of TRAPPIST-1c, specifically the constraints that they place on the history of TRAPPIST-1c’s atmospheric and geological properties. Finally, I will discuss both simulation and observational developments that will aid in understanding rocky planets like TRAPPIST-1c.

Biography: Katie is a 2nd year graduate student in the Department of Astronomy at The University of Texas at Austin. She received a B.S. in Astrophysics and Biology from the University of Florida. There she worked with Sarah Ballard to study the demographics of M dwarf exoplanets and implications for biological evolution. She now works with Caroline Morley, developing and using simulations to model the evolution of CO2-dominated terrestrial planet atmospheres. Broadly, Katie is interested in what makes planets habitable and how to search for both habitable and inhabited planets.

TALK TWO

Speaker: Jialong Ren, Graduate Student, Department of Geological Sciences, UT Austin Jackson School of Geosciences

Host: Brandon Jones

Title: Permeability Limited Compaction and (De)Serpentinization of Ceres

Abstract: The Dawn Mission revealed a surprise that Ceres is still hydrologically active, so its interior structure is important to explain the energy and mass transport at a later stage. In this work, we investigate the compaction history of dwarf planet Ceres with a two-phase flow scheme: viscous compaction of ductile rock coupled with Darcy’s flow in porous media. In such a scheme first used in the differentiation of volatile rich bodies, compaction is limited by pressure gradient required to expel the pore fluid and permeability as a function of porosity. Moreover, we also considered two phase changes: ice-melting and (de)serpentinization.

Biography: My background is in fluid/solid mechanics and numerical simulations. Currently I am interested in planetary science. There are two projects in process: 1) fragmentation and reassembly into rubble piles of planetesimals and 2) compaction and differentiation of small ocean worlds such as Ceres.

RoKafe

DeFord Lecture | Dustin Trail

Traversing the chemical landscape of the early Earth by Dustin Trail, University of Rochester

Abstract:  The conditions that gave rise to life on Earth are still unknown. Despite this, there is broad agreement that the early planet was habitable, with interactions between low-temperature water and rock, potentially creating the substrate upon which life arose. While planetary-scale constraints are a crucial part of habitability, it’s likely that key prebiotic chemistry occurred in smaller, more localized environments. This presentation will examine the early Earth environment on a global scale through zircon chemistry, while also delving into possible local environments and scenarios that may have played a significant role in prebiotic chemistry or the emergence of life.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating DGS graduate student research, is a forum for lectures by distinguished visitors and members of our community. This is made possible through a series of endowments.

UTIG Seminar Series: Nicholas Harmon, WHOI