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UTIG Seminar Series: Fellowship Talks
Start:May 3, 2013 at 10:30 am
End:
May 3, 2013 at 11:30 am
Location:
PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78759
Contact:
Charles Jackson, charles@ig.utexas.edu, 512-471-0401
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Talk 1: “Syn-rift Volcanism and Seafloor-Spreading in the Northern Gulf of Mexico: New Constraints from Marine Seismic Refraction Data” (Drew Eddy)
Abstract:
The Gulf of Mexico (GOM) is a small ocean basin with real rifted margins that formed by continental extension and seafloor-spreading during the Jurassic to early Cretaceous. The lack of good, deeply-penetrating geophysical data in the GOM has precluded prior reconstructions of the timing and location of the transition from rifting to seafloor-spreading, as well as the degree to which magmatism influenced these geological processes. Four marine wide-angle seismic refraction profiles were acquired in the northern GOM from the shelf to deep water as part of the Fall 2010 Gulf of Mexico Basin Opening project (GUMBO). I present data and seismic velocity structures of two GUMBO profiles. On both lines, ocean-bottom seismometers at 10-12 km spacing recorded 150-m spaced airgun shots. I use travel times from long-offset re?ections and refractions to image seismic velocities in the sediments, crystalline crust, and upper mantle using a tomographic inversion. GUMBO Line 3 images a buried volcanic rift margin that extends offshore Alabama and past the Florida Escarpment towards the central GOM. I interpret high velocities (>5.0 km/s) in the sediment layer landward of the Florida Escarpment as a Lower Cretaceous carbonate platform. Seaward of the Florida Escarpment, crystalline crust thins from 23 km to 7 km across a narrow, ~100 km-wide necking zone. Beneath this zone, a deep, localized region of anomalously high seismic velocities at the base of crystalline crust (>7.5 km/s) far exceed velocities in the continental lower crust of the eastern US. I interpret this as potential under-plating and/or infiltration from asthenospheric melts, common at volcanic rifts. At the seaward end of GUMBO Line 3 I find high crustal velocities (6.0-7.5 km/s), a consistent crustal thickness (~7 km), and minor lateral velocity variations that strongly suggest mafic ocean crust produced by normal seafloor-spreading. GUMBO Line 2 extends from offshore Louisiana southward across the Sigsbee Escarpment. The velocity model here images a massive sediment package with noticeable lateral heterogeneities that can be attributed to salt tectonics. GUMBO Line 2 crust thins slightly from north to south, and varies greatly in both thickness (3-10 km) and seismic velocity (6.0-8.0 km/s). I interpret GUMBO Line 2 as a rifted margin that experienced moderate syn-rift volcanism. The crust in the continent-ocean transition zone transitions seaward to ocean crust formed by slow seafloor-spreading. These findings substantially increase the amount of ocean crust traditionally interpreted beneath the GOM, and may thus impact heat flow models for the basin, an important aspect of GOM hydrocarbon maturation. I further suggest that the effects of heat and asthenospheric melt were more impactful and prolonged in the northeastern GOM than in the west.
Talk 2: “Thermodynamic State of Hydrate-bearing Sediment Around the World” (Dylan Meyer)
Abstract:
In situ salinities, calculated from Archie-derived water saturations, in gas hydrate-bearing sediments at ODP Site 1249 and NGHP Site 01-10, located at Hydrate Ridge and the Krishna-Godavari Basin, respectively, show that these hydrate systems are near the three-phase boundary. Chloride concentrations from ODP Site U1328 near Vancouver Island show that this system is not near the three-phase boundary. Massive volumes of gas hydrate have been identified at these sites as well as submarine sediments along continental margins around the world. The stability of these hydrate systems is controlled by the in situ pressure, temperature, and salinity. We determined the in situ water saturation through the incorporation of Logging-While-Drilling data into an iterative application of Archie’s Law. The in situ salinities were calculated through a volumetric relationship between water saturation and the core-derived salinities. The salinity required for three-phase equilibrium was determined using a classic thermodynamic model for gas hydrate. We examined the in situ salinities of hydrate-bearing sediments around the world to gain understanding into the connection between thermodynamic state and the possibility of hydrate dissociation as a result of fluctuating in situ conditions. The in situ salinities at the study sites indicate that Sites 1249 and 01-10 would be more sensitive to changing in situ conditions than Site U1328 and therefore more prone to mass dissociation.
Celebration of the Life of Wann Langston, Jr.
Start:May 5, 2013 at 3:00 pm
End:
May 5, 2013 at 5:00 pm
Location:
Holland Family Student Center, JGB
Contact:
Karen Cochran, kcochran@jsg.utexas.edu
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There will be light food, brief remembrances from friends and family, and casual conversation.
DeFord Lecture | Dr. Richard TaylorApril, 25 2024Time: 4:00 PM - 5:00 PMLocation: Boyd Auditorium (JGB 2.324) Adapting to the Amplification of Climate Extremes Through Freshwater Capture: Evidence from the Tropics by Dr. Richard Taylor, Department of Geography, University College London Abstract: In low-income countries of the tropics undergoing rapid growth, global warming presents challenges to the expansion and sustainability of water supplies required to advance progress toward the United Nations’ Sustainable Development Goals. Substantial uncertainty persists in projections of precipitation under climate change. A widely observed impact, pronounced in the tropics, is the intensification of precipitation comprising a transition towards fewer but heavier rainfalls. How does this transition impact terrestrial water balances? How might these changes influence freshwater demand? I will interrogate these questions and review mounting empirical evidence from the tropics of the resilience to climate change of groundwater resources, which act as a natural inter-annual store of freshwater supporting adaptation to the amplification climate extremes. Presented evidence includes case studies and local-to-regional scale analyses from tropical Africa and the Bengal Basin of South Asia. Outcomes emphasize the interconnected nature of surface water and groundwater as well as the value of groundwater as a natural, distributed store of freshwater. This insight provides a platform to explore more equitable and sustainable water development pathways resilient to climate change. |
UTIG Seminar Series: Cornelia Rasmussen, UTIGApril, 26 2024Time: 10:30 AM - 11:30 AMLocation: PRC 196/ROC 1.603 Speaker: Cornelia Rasmussen, Research Associate, University of Texas Institute for Geophysics Host: Krista Soderlund Title: The Emerging Field Of Position-Specific Isotope Analysis: Applications in chemical forensics, exobiology, geo- and environmental sciences Abstract: Complex organics can be found all over our solar system and within each living thing on our planet, be it as part of its physiology or as a contaminant. However, different processes can lead to the formation of chemical identical molecules. This makes answering a number of scientific questions challenging. One example is distinguishing between biotic and abiotic molecules, hence hindering life detection on early Earth but especially on other planetary bodies, such as on Mars, Titan, Enceladus and on meteorites where organics have been detected. Moreover, tracing molecules as they move through the environment can be demanding, yet is essential in studying the flow of organic molecules as well as correlating pollutants with their source. Novel tools to address these challenges are currently being developed. Especially, the emerging field of position-specific isotope analysis is beginning to grant access to the unique intramolecular carbon (13C/12C) isotope fingerprint preserved in complex molecules. This fingerprint can be applied in various scientific disciplines, ranging from forensics to exobiology, geo- and environmental sciences, including geo health. Nuclear magnetic resonance spectroscopy (NMR) has the potential to become a key player in this research area, as it allows the analysis of organics within complex mixtures, all without the need to fragment the molecule into single carbon units or the combustion of the molecule of interest. We have been developing several NMR tools that allow us to investigate the intramolecular carbon isotope distribution within various molecule classes and to test the central hypothesis that the position-specific carbon isotope distribution within complex organics depends on a molecule’s source and formation history. |
Planetary Habitability Seminar SeriesApril, 29 2024Time: 1:00 PM - 2:00 PMLocation: PMA 15.216B UT Center for Planetary Systems Habitability Seminar Series. See website for speaker schedule and more details: View Events Join remotely: https://utexas.zoom.us/j/94052130734 In person: Classroom 15.216B, Physics, Math and Astronomy Bldg. UT Austin, Department of Astronomy 2515 Speedway, Stop C1400 Austin, Texas 78712-1205 |
UTIG Discussion Hour: Kristian Chan - PhD Talk (UTIG)April, 30 2024Time: 2:00 PM - 3:00 PMLocation: ROC 2.201 |