Lunchtime Seminar Schedule

Dr. Soumya Ray, University of Maryland

A combined investigation of iron and silicon isotopic compositions of achondrites: Insights into differentiation processes

August 31, 2022 at 12:00 pm (CHEM 0215)

Abstract: Meteorites provide an opportunity to reconstruct the history of our Solar System. Differentiated meteorites, also called achondrites, are the products of melting and differentiation processes on their parent body. Stable isotopic compositions of bulk differentiated meteorites and their components can add to our understanding of physical parameters such as temperature, pressure, and redox conditions relevant to differentiation on planetesimals and planets in the early Solar System. In this talk, I will discuss my work on using iron and silicon isotopic compositions of a variety of achondrites that record different degrees of differentiation and redox conditions and what they tell us about the differentiation processes that occurred on their parent bodies.
About the speaker: Dr. Soumya Ray received her Ph.D. from the School of Earth and Space Exploration at Arizona State University (ASU). At ASU, Soumya was a NASA Earth and Space Science Fellow and her research involved utilizing stable isotope compositions of meteorites as proxies for planetary differentiation processes including core formation and partial melting. She has also worked on the mechanical properties of iron meteorites and their implications for asteroid (16) Psyche. At UMD, Soumya works on the CRATER (Characterization of Regolith and Trace Economic Resources) and CORALS (Characterization of Ocean Realms And Life Signatures) orbitrap mass spectrometers.

Dr. Laura Sammon, MathWorks

MATLAB for Geosciences

September 7, 2022 at 12:00 pm (CHEM 0215)

Abstract: Accessing and visualizing data is a critical requirement for researchers trying to gain information about, and insight into, natural phenomena. However, just connecting to and processing scientific datasets can sometimes result in large hurdles and time sinks. MATLAB® has many capabilities for working with and visualizing geospatial data and other popular scientific data formats. New features make data handling and viewing much easier and require less coding. In this seminar, we will use MATAB to demonstrate how to automate your data retrieval, plotting, and analysis techniques. Along the way, we’ll show you some new (and old) tips and tricks for working with geoscience data in MATLAB, useful functions, and where to access further resources. We will wrap up by discussing how you can ensure your results are Open Access, because sharing your data is crucial to adding value to your science.
After the demonstration, MathWorkers (Laura Sammon and Evan Cosgrove) will answer questions about MATLAB and other MathWorks products, and also about their graduate school/post graduate experiences, career paths, and opportunities.

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About the speaker: Dr. Laura Sammon earned her Ph.D. at the University of Maryland in the spring of 2022, and shortly after became a Customer Success Engineer for MathWorks. Her graduate research focused on Earth’s composition, especially the composition of the deep continental crust, and on neutrino geoscience. Now, as a MathWorks CSE she drives the adoption of MATLAB for Earth and ocean sciences, teaching researchers how to use MATLAB efficiently while advocating for the geoscience community’s technical needs at the company.

Dr. Emilie Dunham, University of California, Los Angeles

Using Meteorite Inclusions to Learn About the Architecture of our Solar System

September 14, 2022 at 12:00 pm (Virtual)

Abstract: Ca-Al-rich inclusions (CAIs) are the first-formed solids in the Solar System, forming 4.56 billion years ago, and act as tracers of movement in the disk. CAI populations in different chondrites are all unique with respect to CAI size, abundance, and type; my goal is to figure out why this is to constrain the dynamics in the disk at this early stage. I will present about how I doubled the number of CAIs found in inner Solar System meteorites (ordinary and enstatite chondrites) and then statistically compared their size, abundance, mineralogy, and isotope systematics, to outer Solar System meteorite CAIs. I will also talk about my 2019-2020 trip to Antarctica with the ANSMET team to search for meteorites.
About the speaker: Dr. Emilie Dunham is currently a 51 Pegasi b postdoctoral fellow jointly at UCLA and UCSC studying ancient meteorite inclusions to constrain the Jupiter gap model. She obtained her PhD from ASU in 2020 where she measured short-lived radionuclides in meteorite inclusions. She is passionate about mentoring and DEI activities to foster a welcoming scientific environment.

Dr. Brendan Anzures, Lunar and Planetary Institute/NASA Johnson Space Center

Sulfur speciation and Solubility at Very Reducing Conditions Applied to Mercury and Enstatite Chondrites

September 21, 2022 at 12:00 pm (Virtual)

Abstract: MESSENGER revealed that lavas on Mercury are enriched in sulfur (1.5-4 wt.%) compared with other terrestrial planets (<0.1 wt.%) due to high S solubility under its very low oxygen fugacity (ƒO2). To understand S solubility and speciation in reduced magmas, S K-edge XANES spectra were collected in 60 experiments that span a range of P (177 bar to 5 GPa), T (1225 to 1850 °C), and ƒO2 (IW-0.8 to IW-8.6) using new XANES standards [1] and XANES unmixing technique [2]. We find that as ƒO2 decreases from IW-2 to IW-7, S speciation in silicate melt goes through two major changes. At IW-2, FeS and FeCr2S4 species are destabilized, and CaS becomes the dominant S species with minor Na2S and MnS. At IW-4, MgS is the dominant S species with minor CaS. The S speciation changes have substantial impacts on physicochemical properties such as viscosity, melting temperature, and mineral stability, which led to Mercury’s distinct evolution.
[1] Anzures et al. (2020) Am. Min.
[2] Anzures et al. (2020) GCA.
About the speaker: Dr. Brendan Anzures (LPI/ARES postdoctoral researcher) is a planetary petrologist and geochemist with a spectroscopist twist interested in the chemical, thermal, and redox evolution of airless rocky bodies in the early solar system (Mercury, meteorites, and asteroids). He uses high-pressure, high-temperature experiments and meteorites to understand the chemical behavior of planetary materials at depth and at the surface, with a special focus on the behavior of volatiles (S, C, F, Cl, H).

Dr. Julianne Fernandez, University of Maryland

A Methane Tail of two European Cities

September 28, 2022 at 12:00 pm (CHEM 0215)

Abstract: Recent research has shown that urban methane (CH4) emissions are influenced by local utilities, especially a city’s natural gas distribution network (NGDN). National inventories, e.g. UK National Atmospheric Emission Inventory (NAEI), do not accurately represent the spatial distribution of natural gas leaks throughout a city, as estimates of emissions are averaged over an area using population density as an emission factor. Therefore, there is a need for more precise information to allow local governments and utilities to effectively prioritize activities to take on the task of mitigating CH4 emissions.
Presented here are measurements and emission quantifications of urban CH4 emissions from a western European city (London, U.K) and an eastern European city (Bucharest, Romania), which differ culturally, governmentally, and economically. Extensive mobile surveys were conducted from 2018 to 2019, measuring street-level CH4 mole fractions, ethane (C2H6), and analyzing δ13CCH4 and δ2HCH4 for additional source type determination.
Compared to other recently measured cities, both Bucharest (1832 tons CH4 yr-1) and London (~2220 tons CH4 yr-1) had greater city-wide emission rates than Paris, France, and Hamburg, Germany. Isotopes (δ13CCH4 & δ2HCH4) and ethane-methane ratios (C2:C1) were used extensively in an attempt to identify the main sources of CH4 in both cities. In Bucharest, both tracers showed the greatest emission dominance from wastewater (58%-63%), where less than half (32%– 42%) were fossil fuel, and 0-5% were pyrogenic. Source tracers for London indicated a dominance of fossil fuel emissions (86% to 91%) and the remaining emissions attributed to biogenic (7%-14%) and pyrogenic (2%) sources. These data will help local governments with emission compliance and prioritize greenhouse gas mitigation strategies.
About the speaker: Dr. Julianne M. Fernandez recently finished her Ph.D. at Royal Holloway University of London, with the Greenhouse Gas Research Laboratory in the Department of Earth Sciences. Where her research focused on source identification of methane emissions from urban cities using high-precision stable isotopic measurements coupled with mobile measurement techniques. Previously, Fernandez completed her Master's in Geology at the University of Cincinnati, where her research was centered on methane and nitrous oxide surface water emissions from Lake Erie, a eutrophic freshwater body of the North American Great Lakes. Fernandez recently joined the UMD PanoLab with James Farquhar and is continuing research in urban methane and source apportionment.

Prof. Sarah Mazza, Smith College

Solving the mystery of Bermuda: A unique volcanic history

October 5, 2022 at 12:00 pm (Virtual)

Abstract: Bermuda is an intraplate volcano found off the coast of the Carolinas in the Atlantic Ocean. New geochemical data suggest that Bermuda sampled a previously unknown mantle domain, characterized by silica undersaturated melts that have significant enrichments in incompatible elements and volatiles, and a unique, extreme isotopic signature (Mazza et al., 2019). Bermuda records the most radiogenic 206Pb/204Pb isotopes ever documented in an ocean basin (19.9-21.7), coupled with low 207Pb/204Pb (15.5-15.6) and relatively invariant Sr, Nd, and Hf isotopes, suggesting that this source must be <650 Ma.  These silica undersaturated melts are interpreted to be sourced in the transition zone, tapping a young mantle reservoir that resulted from recycling and storage of incompatible element and volatile rich material. Ongoing work explores the nature of the carbonate source for Bermuda with thin section analysis of ocelli and stable zinc isotopes.
About the speaker: Dr. Sarah Mazza did her undergrad at UNC-Chapel Hill and moved to Virginia Tech for her masters in Structural Geology. She stayed at Virginia Tech for her PhD but switched over to the 'dark-side' to study mantle geochemistry. Her research focused on understanding non-mantle plume derived intraplate volcanoes, by studying both magmatism in Virginia and Bermuda. After VT, Sarah moved to Muenster, Germany for a post-doc at the Institute for Planetology exploring stable W isotopes in arcs. She is now an Assistant Professor at Smith College in Massachusetts.

Dr. Amaury Bouyon, University of Maryland

Multiple Sulfur isotope record of Brazilian Archean sediments, challenging the homogeneity of the Archean record

October 12, 2022 at 12:00 pm (CHEM 0215)

Click here if you would like to meet with the speaker.


Carl Martin, University of Cambridge

Adventures in ULVZland: a global quest for hidden signals and taming unwieldy non-linear inversions

October 19, 2022 at 12:00 pm (CHEM 0215)

About the speaker: Carl Martin did his undergraduate at the University of Cambridge, reading Physics at the Cavendish Laboratory via Natural Sciences. He remained in Cambridge to do his graduate studies due to Stockholm syndrome, but defected to the Earth Sciences Department. He can usually be found organising a BBQ, shouting at a computer, or having a nap on the sofa in his office. Carl is interested in gathering and mining datasets related to the core-mantle boundary, and applying them to Bayesian methods.

Dr. Nico Küter, ETH Zürich

Water speciation in hydrous Stishovite

October 26, 2022 at 12:00 pm (Virtual)


Dr. Quinn Shollenberger, Lawrence Livermore National Laboratory

Applications of Samarium Isotopes to Pre- and Post-detonation Nuclear Forensics

November 2, 2022 at 12:00 pm (Virtual)


Dr. Christian Renggli, University of Münster

Sulfur on the Moon and Mercury

November 9, 2022 at 12:00 pm (Virtual)

Abstract: The terrestrial Moon and the innermost planet Mercury share remarkable similarities. The are both very reduced planets and they lack atmospheres. At the reducing conditions the behavior of sulfur differs considerably from that on Earth, Mars, or Venus, and S occurs entirely in its reduced form. In this talk I will provide an overview of what is known about S on the Moon and Mercury, from more than 50 years of lunar sample research and observations from the recent NASA MESSENGER mission to Mercury. I will present results from experimental approaches that allow us to constrain the behavior of S at the surfaces of these two planets, in fumarolic and volcanic processes.
About the speaker: Dr. Christian Renggli is originally from Bern in Switzerland, where he obtained a Bachelor degree in Earth Sciences. He continued his studies in Munich, Germany, where he obtained a Master of Science in Geomaterials and Geochemistry with a focus on volcanology. In his PhD research at the Research School of Earth Sciences, Australian National University, he investigated the reactive behavior of SO2 in volcanic processes experimentally.
Since 2018 he is a postdoctoral researcher at the Institute for Mineralogy, University of Münster in Germany. His main research interest lies in applying experimental methods to understand high-temperature gas-solid reactions on Earth and other planetary bodies. He investigates the reaction of S-bearing gases with melts, glasses and rocks. This experimental work addresses fundamental questions of how chemical elements are mobilized and deposited in ore forming magmatic systems and in explosive volcanic eruptions, and also how surfaces of other S-rich planetary bodies, such as Mercury, are modified. Furthermore, he conducts experiments to investigate the transport of metals in volcanic gas, and how volatile elements (H, S, Cl, F and C) control the volatility, degassing behavior from silicate melts and deposition of trace metals.

Samantha Jacob, Arizona State University

Spectra and mineralogy of Mt. Sharp units explored by the Curiosity rover

November 16, 2022 at 12:00 pm (Virtual)

About the speaker: Samantha Jacob was born and raised in Colorado where she fell in love with space from stargazing in her backyard. She went to the University of Hawaii at Manoa for her bachelor's and masters in geology. It was during her masters that Samantha started working with the Curiosity rover team, which continues during her PhD at Arizona State University. Samantha hopes to keep working in space exploration and eventually go to space herself.

Dr. Richard Windmill, The Open University

Understanding the early history of a differentiated protoplanet: the main group pallasite parent body as a case study

November 30, 2022 at 12:00 pm (Virtual)


Dr. Natasha Almeida, The Natural History Museum, London

The Natural History Museum Meteorite Collection - past, present & future

December 7, 2022 at 12:00 pm (Virtual)


The coordinator for the Colloquium Series is Dr. Jan Hellmann. You can contact him at hellmann [at] umd [dot] edu.