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10:30 am - UTIG Fellowship Talks

UTIG Fellowship Talks

  Start: May 2, 2014 at 10:30 am     End: May 2, 2014 at 11:30 am
 Location:PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
 Contact:Nick Hayman, hayman@ig.utexas.edu, 471-7721
 URL:Event Link
"Simulations of Seafloor Methane Venting from Warming-Induced Hydrate Destabilization" (by Kristopher Darnell)

We show with a dynamic, multiphase, fluid-flow model that free gas can temporarily vent through the marine hydrate stability zone and flux into the ocean during the transient response to warming. Our analysis indicates that the venting results from elevated salinities in the upper regions of the sediment column as dissociated free gas migrates upward and forms secondary hydrate, expelling salt from the hydrate cage. The elevated salinities produce a temporary three-phase equilibrium co-existence throughout the sediment column that persists until the gas charge is depleted. The salinity eventually relaxes to a steady-state seawater profile and a hydrate deposit of decreased mass spans the hydrate stability zone. This transient behavior provides a new explanation for methane vents that appear to display gas flow through the hydrate stability zone and, furthermore, may explain past venting events that were the sources for now relict seafloor pockmarks.
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"A replicated record of northern Gulf of Mexico climate variability during the late Holocene" (by Kaustubh Thirumalai)

Sea-surface temperatures (SST) in the Gulf of Mexico (GOM) are an important influence on the moisture budget of the Western Hemisphere and play a key role in tropical to extra-tropical heat transport in the region. Changes in the hydroclimate of the GOM region also influence sea-surface salinity (SSS). Marine sediment records from the Pigmy Basin suggest significant SST variability in the northern GOM over the last two millennia. Some, but not all of this SST variability is also observed in paleoclimate records from the Caribbean-GOM region. To assess the spatial coherency of a regional SST signal, we present marine sediment records from another GOM basin, Garrison Basin (26°43'N, 93°55'W), which is located ~250 km west of Pigmy Basin. We generated time series of paired Mg/Ca (SST proxy) and ?18O (SST and SSS proxy) variations in planktic foraminifer Globigerinoides ruber (white variety) from two multi-cores collected in 2010. A radiocarbon-based chronology indicates that these cores span the last 4400 calendar yrs BP. Initial stable isotopic results reveal excellent replication between the multi-cores and indicate coherent, centennial variability in foraminiferal ?18O. Preliminary Mg/Ca-SST results from one of the cores compare well with published results from the Pigmy Basin. Our replicated results in tandem with a Mg/Ca-?18O calibration study from a sediment trap located ~350 km east of the Garrison Basin lend confidence that replicated downcore geochemical variations in this region are a robust record of paleoclimate variability.
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"Gulf of Alaska continental slope morphology: Evolution of a glaciated transform margin" (by John Swartz)

The onset of glaciation in the active St. Elias orogeny in southeast Alaska resulted in massive sediment flux to the Gulf of Alaska, but the resulting sedimentary systems of the continental slope remain poorly understood. During glacial periods ice streams advance across the continental shelf, carving troughs that reach the shelf edge and route sediment to the continental slope and deep sea fan systems.

High-resolution multi-beam data is used to develop the relationship between the Yakutat and Alsek Sea Valleys and the resulting continental slope morphology. The shelf and slope geomorphology can be divided into statistical groupings that relate to the relative balance of erosion and deposition. Our analysis shows that only the paleo-ice stream eroding the heart of the St. Elias orogen has been able to build an incipient Trough-Mouth Fan. The massive sediment supply from this region was able to overwhelm the steep initial topography of the transform margin, while further to the east sediment slope-bypass dominates.

This analysis provides an extreme end member to existing studies of temperate glaciation along continental margins. The unique interplay between rapid uplift due to ongoing collision and the massive erosion caused by temperate glaciers provides for sedimentary flux far above most other systems. This sediment supply allows for formation of progradational trough mouth fans in a system that is otherwise completely unfavorable to slope deposition and progradation.






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5:00 am - Alumni Reception in conjunction with the SW Section meeting of AAPG

Alumni Reception in conjunction with the SW Section meeting of AAPG

  Start: May 12, 2014 at 5:00 am     End: May 12, 2014 at 7:00 am
 Location:Petroleum Club of Midland
 Contact:Kristen Tucek, ktucek@jsg.utexas.edu, 512-775-6745

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