Events

Lithosphere and Dynamic Earth seminar: Wanying Wang

DeFord Lecture | Steven Davis

Global and regional drivers of land-use emissions

Dr. Steven Davis, University of California, Irvine

Abstract: Human uses of land have transformed and fragmented ecosystems, degraded biodiversity, disrupted carbon and nitrogen cycles and added prodigious quantities of greenhouse gases (GHGs) to the atmosphere. However, in contrast to fossil-fuel carbon dioxide (CO2) emissions, trends and drivers of GHG emissions from land use (including both land-use change and agriculture) have not been as comprehensively and systematically assessed. I’ll present recent work my group has done to analyze country-, process-, GHG- and product-specific inventories of global land-use emissions over the last half-century, including uncertainties and decomposition of key demographic, economic, and technical drivers. I’ll then present results of a related analysis of the land-use emissions embodied in international trade and discuss implications for mitigation efforts. Finally, I’ll briefly introduce the Carbon Monitor, an international collaboration hatched during the pandemic to estimate global, country, and U.S. state-level fossil emissions in near real time.

DeFord Lecture Series
Since the 1940’s, the DeFord (Technical Sessions) lecture series, initially the official venue for disseminating EPS 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.

BEG Seminar: Richard Sech - Shell

Bureau Seminar Series

UTIG Seminar Series: Lynnae Quick, NASA Goddard

Water, Climate and Environment Seminar | Xinyue Ye - Texas A&M U.

Urban development and its interactions with climate, water and environment

EPS Faculty Meeting

Masters "Thursday" Presentations

Please help us celebrate the accomplishments of our graduating Masters students by joining us for a special DeFord Presentation next Thursday (12/9) at 12:30 pm.

Please join us at the following link: https://utexas.zoom.us/j/96370762511

This Fall’s Masters Presentations event will be “klein aber fein”, with two outstanding presentations scheduled:

Xin Liu (Advisor Mrinal Sen): Feasibility of Prediction of Principal stress from reflection seismic data

Matthew Nix (Advisor Brian Horton): Shifts in deposition, sediment dispersal, and provenance for the late Jurassic-early Cretaceous Kootenay and Blairmore Groups: Implications for foreland basin dynamics in western Canada

BEG Seminar: Olvier Duffy - Bureau of Economic Geology

Bureau Seminar Series

UTIG Seminar: AGU Practice Talks

In a now annual tradition, the last seminar of the Fall Semester features talks by UTIG graduate students.

Speakers: Cat Ross & Shuai Yan, Graduate Research Assistants, University of Texas Institute for Geophysics
 
Cat Ross: Zircon (U-Th)/He Impact Crater Thermochronometry and the Effects of Shock Microstructures on Helium Diffusion Kinetics

Abstract: Accurate and precise age determination of impact cratering events remains challenging and often contentious; less than half of all known craters are regarded as accurately and precisely dated. Zircon (U-Th)/He (ZHe) dating of impactites can be employed to date medium to large impact structures as ZHe ages can be fully reset in minutes at T >1000°C, a plausible scenario in the central melt pool. In contrast, complete resetting of ZHe at 200-300°C, encountered near the crater margins or due to post-impact hydrothermal overprinting, may take >103-6 years. To test the reliability of ZHe impact dating, we have quantified the effects of shock-induced microstructures on helium diffusion kinetics in well-characterized variably shocked zircon. We investigated samples from two impact structures, the Chicxulub multi-ring crater and Ries complex crater, to compare diffusion kinetics from structures with different size, age, and hydrothermal system longevity. Shock microstructures were characterized by backscattered-electron imaging prior to determining the He diffusion kinetics by prograde and retrograde fractional-release experiments via light-bulb furnace with incremental step-heating (10°C) from 300°C to 600°C. Next, we examine the internal interconnectivity and sizes of the diffusion domains by electron backscatter diffraction (EBSD). While we found that zircon with few shock microstructures exhibited no marked deviation from helium diffusion kinetics of undamaged zircon, zircon grains with planar microstructures and granular textures are characterized by a dramatic decrease in helium retentivity due to the reduction in the effective domain size and the introduction of interconnected fast diffusion pathways. A subset of grains were ZHe dated and showed that less deformed grains yielded a weighted mean age within error of the accepted impact ages, while the grains with planar microstructures or granular textures gave systematically younger ages. These new diffusion data and ZHe ages demonstrate that highly shocked grains are unsuitable for ZHe impact crater dating. Therefore, detailed characterization of impact-induced microstructures is critical for determining accurate ZHe impact ages and offers the possibility of investigating post-impact hydrothermal circulation.

Shuai Yan: A widespread subglacial hydrology system detected by airborne geophysics survey in Princess Elizabeth Land, East Antarctica

Abstract: Measurements of the subglacial topography, geology and hydrology of Princess Elizabeth Land (PEL), East Antarctica is critical for our understanding of the dynamics of the East Antarctic Ice Sheet (EAIS). However, PEL has been one of the least surveyed sectors of East Antarctica. Over the past years, several collaborative airborne geophysical surveys have been performed in PEL, aiming to fill in this gap. In this presentation, we propose to show the newly collected geophysical evidence suggesting the existence of a widespread subglacial hydrology system in PEL. This subglacial hydrology system is composed of a large subglacial lake (hereby referred as Lake Snow Eagle, LSE) that is over 40 kilometers long and 10 kilometers wide, and multiple smaller subglacial water bodies around LSE. The existence of these subglacial water bodies provides important constraints on the basal thermal condition in this region. We also propose to address the possibility that this subglacial hydrology system is connected to the coastal regions by an extensive subglacial channel network, which would make it the largest known-to-date interior Antarctic subglacial hydrology system that has a potential direct hydraulic pathway to the ocean.