Geology Faculty Lightning Talks, UMD Geology
August 30, 2024 at 11:00 am (ESJ 0215)
Speaker Title
Karen Prestegaard Watershed responses to land use and climate change
Sujay Kaushal The Anthropogenic Salt Cycle
Wenlu Zhu Creating fault Zone
Richard Walker Earth's Genetics: and Yours Too!
Laurent Montesi Planet-hopping
Anshuman Swain, University of Michigan
Linked Ecologies: Connecting Invisible Pasts, and Actionable Futures
September 13, 2024 at 11:00 am (ESJ 0215)
Species do not exist in isolation from each other and their environments. The interactions among and between them form the backbone of ecosystems and their biodiversity. In this talk, the speaker will focus on investigating how abiotic and biotic interactions structure species, communities, and ecosystems across different spatiotemporal scales based on three important topics in global change biology. The first two topics will leverage the fossil record to explore how long-term climate change impacts global and local communities. In specific, marine micropaleontological records will be used to understand the response of ecological communities to environmental drivers, and terrestrial fossil plant-insect associations will be utilized to explore how ecological interactions are shaped by the environment and eco-evolutionary histories. The third topic will focus on how short-term eco-environmental feedbacks shape ecosystems, investigating ecological tipping points and modern food webs. Overall, the talk will summarize how paleontological and ecological informatics inform us about past and present patterns of environment-driven changes in biodiversity and in doing so, help us understand the impact of future global change.
Mehdi Benna, NASA Goddard Space Flight Center
The Lunar Environment Monitoring Station for Artemis 3: A new type of instrumentation for a new era of lunar exploration.
September 20, 2024 at 11:00 am (ESJ 0215)
The Lunar Environment Monitoring Station for Artemis 3 (LEMS-A3) is one the three lunar instruments selected for implementation and deployment as part of NASA’s forthcoming Artemis III mission, humanity’s first return to the lunar surface in more than 50 years. LEMS-A3 is a compact, autonomous, and self-sustaining seismometer suite designed to carry out continuous (day and night), long-term monitoring of the lunar seismic environment at the South Polar region. Once deployed on the surface and activated by the Artemis 3 (A3) crew, it requires no support (power, thermal, commanding, or data) from the Human Landing System (HLS) or the A3 crew to operate. The LEMS-A3 station continues operations for its target two-year longevity goal, long after the A3 HLS and crew has departed the Moon.
Jie Deng, Princeton University
Mantle heterogeneities originated from the Earth’s core: A new model
September 27, 2024 at 11:00 am (ESJ 0215)
The Earth’s lowermost mantle harbors two large low shear-wave velocity provinces with patches of ultra-low velocity zones. These structures exhibit distinct seismic and geochemical signatures compared to the surrounding mantle. Yet, their origin remains enigmatic. Here, I propose a new long-term core-mantle chemical interaction model termed basal exsolution contaminated magma ocean (BECMO) which considers the addition of oxide exsolved from the core into the basal magma ocean. As a first step, I will show that oxide exsolved from the core can selectively deliver core-like signatures, by leveraging large-scale atomistic simulations powered by cutting-edge machine learning techniques and density functional theory. I then delve into the long-term interaction of core-derived exsolution and the mantle, and present geodynamic modeling and thermodynamic modeling results of the BECMO mantle and discuss the implications for forming deep mantle geochemical and geophysical heterogeneities of various scales.
Thomas Holtz, University of Maryland
New Advances in Tyrannosaur Functional Morphology, Paleoecology, Ontogeny, and Taxonomy
October 18, 2024 at 11:00 am (ESJ 0215)
Tyrannosaurs (Tyrannosaurus rex and the other Tyrannosauridae, as well as earlier relatives) provide an excellent opportunity for exploring evolution and adaptation within Dinosauria, being represented by species spread out over a 100-million-year period, many of which include multiple relatively complete specimens sometimes. New analytic techniques have yielded insights about various aspects of their biology. Examination of the surface texture and histology of the metatarsals (long bones of the feet) support earlier hypotheses of increased resistance to torsion relative to other carnivorous dinosaurs; these data and biomechanical modeling indicate greater agility than other large theropod dinosaurs. While all large-bodied dinosaurs underwent orders of magnitude increase in size during growth, in tyrannosaurids particular profound transformations (particularly of the skull) between juvenile and adult phases. Paleoecological modeling suggests that young tyrannosaurids represent the otherwise-missing middle-sized predators of their ecosystems (niches previously occupied by other groups of dinosaurs.)
Yuanzhi Tang, Georgia Institute of Technology
A geochemist’s approach for critical mineral resource recovery
October 25, 2024 at 11:00 am (ESJ 0215)
In the natural environment, biogeochemical reactions influence the fate and transport of contaminants, nutrients, and metals, shaping planet surface and influencing human development. One big challenge in understanding the biogeochemical cycles of elements across geosphere-biosphere-hydrosphere-atmosphere is to correlate the molecular scale speciation with larger scale reactions. My research focuses on the fundamentals and applications of such speciation-reactivity correlations at mineral-water interfaces, such as those related to the cycling and recycling of metals and nutrients. In order to isolate, quantify, and integrate the fundamental mineralogical and biogeochemical factors influencing these processes, we conduct multidisciplinary investigations across temporal and spatial scales. In this talk, I will give an example of our research on critical mineral resource recovery to demonstrate the importance of understanding molecular scale interfacial processes. Rare earth elements (REEs) are critical for the sustainable development of clean energy and high technology. The high demand and import dependence have prompted the US to explore new resources and develop environmentally friendly technologies for REE extraction, processing, and manufacturing. Recovery of REEs from waste streams is a promising resource recovery and waste valorization option that might bring about significant economic and environmental benefits. However, many challenges need to be addressed in order to develop cost effective and environmentally friendly techniques for REE recovery. This talk will discuss the systematic characterization of REE speciation in combustion residue and the subsequent rational design of an integrated system for REE recovery and waste reduction.
Elizabeth Cottrell, Smithsonian Museum of Natural History/Department of Mineral Sciences
The Mantle (peridotite) Record of Mantle Redox
November 1, 2024 at 11:00 am (ESJ 0215)
Oxygen is the most abundant element in Earth’s mantle, and its chemical potential, fO2, influences mantle processes such as melting and volatile extraction, production and composition of Earth’s crust, the generation of ore bodies, and regulation of the atmosphere. Understanding how mantle fO2 has varied in space and time is central to understanding Earth’s present-day processes and past evolution. Development of new fO2 proxies, combined with newfound understanding of the importance of mantle fO2 in Earth evolution, have driven new observations, experiments, and models and led to controversies concerning the fO2 of modern convecting mantle, whether fO2 has varied with time, and to what extent it influences crustal differentiation.
The fO2 of convecting upper mantle recorded by ridge peridotites varies by more than four orders of magnitude. Although much attention has been given to mechanisms that drive variations in mantle fO2 between tectonic settings and to comparisons of fO2 between modern rocks and ancient-mantle-derived rocks, comparatively little has been done to understand the origins of the high variability in fO2 recorded by peridotites from modern mid-ocean ridge settings. In this talk I’ll share what we have learned from mantle peridotites about ancient and modern mantle redox, and also highlight recent results from Birner et al., 2024.
Max Lloyd, Penn State University
How well do plants breathe in glacial climates?
November 8, 2024 at 11:00 am (ESJ 0215)
Land plant photosynthesis today represents about half of global gross primary productivity. During the last glacial period, land plant productivity was reduced, potentially by a factor of two. The specific cause of the terrestrial biosphere contraction during glacial periods is uncertain, but important for understanding controls on climate in the past and near-future. One hypothesized explanation for this productivity decline is low atmospheric CO2 concentrations at the time, because when [CO2] is low, modern plants can release nearly as much carbon through photorespiration as they take in through photosynthesis. This could stress and starve plants at an individual level and perhaps at a global scale.
However, direct evidence that high photorespiration suppressed glacial terrestrial productivity is limited. I will describe new work applying a recently developed proxy for the relative rate of photorespiration to photosynthesis based on clumped isotopes in wood methoxyl groups. We applied this proxy to samples of wood from across North America that span the last glacial period to the present. We find that photorespiration rates vary in space and time. Specifically, trees from the last glacial period below ~40°N tended to photorespire more than those from higher latitudes and more than trees from similar locations in the more recent past. These differences can be reconciled with a single relationship between temperature, [CO2], and photorespiration. This suggests that despite environmental adaptations, trees from the glacial period experienced elevated photorespiratory stress compared to more recent counterparts. This provides direct evidence that CO2 starvation restricted land plant productivity during glacial intervals.
Michael Brown, UMD Department of Geology
Is plate tectonics a post-Archean phenomenon? A petrological perspective
November 22, 2024 at 11:00 am (ESJ 0215)
The petrogenesis of contemporary igneous and metamorphic rocks is commonly explained by plate tectonics, but how far back in time does this relationship hold? Here we investigate whether the distinctive petrological features of recent ocean crust, subduction-related magmatism and regional metamorphism can be unambiguously identified in the Archean geological record. From an igneous perspective based on geological relationships and Th–Nb systematics, it is difficult to claim that any Archean 'ophiolite' was part of a global plate system rather than deriving from a plume ascending through attenuating lithosphere. Furthermore, the rarity of subduction-related rocks, particularly their plutonic equivalents, which have good preservation potential, is consistent with the concept of local convergence and short-lived subduction. From a metamorphic perspective, the appearance of orogenic eclogites in the Paleoproterozoic, the widespread occurrence of blueschists and ultrahigh-pressure metamorphic rocks since the late Neoproterozoic, and a change from a unimodal to a bimodal distribution of metamorphic T/P during the Proterozoic, are responses to secular cooling and the evolution of global tectonics since the Archean. Our petrological perspective is that plate tectonics analogous to that on Earth today is probably a post-Archean phenomenon.
The coordinator for the Colloquium Series is Dr. Mengqiang "Mike" Zhu. You can contact him at mqzhu [at] umd [dot] edu.
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