JSG Events

Soft Rock Seminar

UTIG Seminar Series: Douglas Foster, ConocoPhillips

"Amplitude Interpretation of Seismic Reflections"

Abstract:

The effects of changes in rock and fluid properties on the amplitude of reflection seismic waves are described. This analysis is commonly known as amplitude versus offset (AVO) analysis. Attributes characterizing the seismic response are useful for determining subsurface rock and fluid properties. In the slope-intercept domain, reflections from wet sands and shales fall on or near a trend, which we call the Fluid Line. Reflections from the top of sands containing gas or light hydrocarbons fall on a trend approximately parallel to the Fluid Line; reflections from the base of gas sands fall on a parallel trend on the opposing side of the Fluid Line. Typically, rock properties of sands and shales differ, and therefore, reflections from sand/shale interfaces are also displaced from the Fluid Line. The distance of these trends from the Fluid Line depends upon the contrast of the ratio of P-wave velocity, Vp, and S-wave velocity, Vs. This ratio is a function of the pore fluid compressibility and implies that distance from the Fluid Line increases with increasing compressibility. Reflections from wet sands are closer to the Fluid Line than hydrocarbon related reflections. Porosity changes affect acoustic impedance, but do not significantly impact the Vp/Vs contrast. As a result, porosity changes move the AVO response along trends approximately parallel to the Fluid Line. These observations are useful for interpreting AVO anomalies in terms of fluids, lithology and porosity.

UTIG Seminar Series: Dr. John Dewey, Natural History Museum, London

"Transtension in the Eastern California Shear Zone"

Abstract:

A major problem of structural geology is how biaxial, uniaxial, and triaxial strains in the brittle upper crust are effected by fault systems. Transtension generates noncoaxial constriction and poses difficult problems of wrench/normal fault-combination block rotation and strain. Normal faults rotate around vertical and horizontal axes to give oblique slip, and wrench faults rotate around vertical axes. Kinematic problems arise because blocks of varying size and shape bounded by normal and wrench faults rotate at different rates about vertical and horizontal axes while shortening or lengthening. Compatibility problems may be solved by block margin deformation, by bulk block strain, by buckling of faults, by volume increase with holes opening at block intersections, by alternating periods of normal and wrench faulting, by discrete arrays of normal and wrench faults. The Coso transtensional region, in southern California is active, the horizontal strain rates are high, and there is a huge amount of seismic, heatflow, fluid flow, and borehole and surface geologic data. Between the Sierra Nevada and the Argus Range, the transport direction (from GPS) is roughly NNW at about 10 mmyr. This generates triaxial constriction with an instantaneous stretching direction roughly WNW and a horizontal strain rate of about 10-14 sec-1. Constriction is modeled by a combination of NNE normal faults, NE wrench faults, and WNW folds and thrusts, which rotate clockwise with vorticity, and N wrench faults that rotate counterclockwise against vorticity, a pattern of faulting, folding, and bulk strain recorded closely by fault slip data from earthquakes and field observations. In deformation zones, GPS and moment tensor sum data indicate very smooth velocity fields, which in turn means that the commonly accepted view of the rotation of large rigid blocks cannot be correct; instead, the upper crust behaves as a "continuum rubble" of very small "blocks".

GSA South Central Section Meeting

47th Annual Meeting of the South Central Section, Geological Society of America
Hosted by the University of Texas at Austin

GSA South Central Section Meeting

47th Annual Meeting of the South Central Section, Geological Society of America
Hosted by the University of Texas at Austin

Soft Rock Seminar: Alex Parker, DGS

Outcrop Characterization of Grayburg Ooid Grainstones in the Guadalupe Mountains, NM

UTIG Seminar Series: Clara Deser, NCAR

"Climate Projections over North America in the Coming Decades: Uncertainty due to Natural Variability"

Abstract:

Future climate change at local and regional scales will result from a combination of human and natural factors. In this talk, I show that unpredictable, internally-generated climate fluctuations make a substantial contribution to climate trends projected for the next fifty years over North America. My results are based on large ensembles of climate change integrations with two state-of-the-art coupled climate models. I will also show that the large-scale atmospheric circulation is responsible for much of the diversity in climate change projections across the individual ensemble members. I conclude by discussing some implications of the results for model validation, inter-model comparisons, and interpretation of observed climate trends.

Hydro Brown Bag: Ben Tobin,Texas State University

Soft Rock Seminar: Jessi Kopp, DGS

THE EFFECTS OF VARYING SUBSIDENCE IN A FLUVIO-DELTAIC SYSTEM:
Responses to Lateral Tectonic Tilting in 3D Physical Models Applied to the Ganges-Brahmaputra Delta

UTIG Seminar Series: Nicholas Schmerr, Planetary Geodynamics Lab

"Seismology in the Solar System: Exploring the Interiors of the Planets"

Abstract:

Understanding the internal structure of objects such as planets and moons is essential for deciphering the formation and evolution of our Solar System. Seismology provides a powerful tool for accessing the detailed innards of these objects, allowing the linkage of surface observables provided by remote sensing, geochemistry, petrology, volcanology, dynamics, and tectonics to deep internal processes. On Earth, seismological remote sensing has led to a revolution in our understanding of Earth¹s interior, allowing us to probe the driving mechanisms behind mantle convection and study the detailed evolution of the atmosphere, oceans, crust, mantle, and core. Today, seismological science has been in a golden era of seismic data acquisition and analysis. In this talk, I will present recent research into understanding the structure at the base of a tectonic plate and Earth's upper mantle; research that takes advantage of the multitude of seismic data freely available to the scientific community. While our understanding of Earth¹s interior grows, we only have a tantalizing glimpse of planetary interiors elsewhere in the Solar System, with seismic datasets provided by instruments deployed by the Apollo astronauts on the Moon and data from the Viking II mission to Mars. I will present some of my latest work that is combining observations from the Apollo seismic dataset with GRAIL mission gravity measurements and LRO high resolution imaging to further improve our knowledge of the Moon's crustal structure and deep interior. In addition, future missions are currently underway to develop and deploy new seismometers in the Solar System (e.g., InSight). Deployment of seismometers across a wide variety of objects will usher in a new era of planetary exploration, allowing us to link the evolution and dynamics of planetary interiors across a wide variety of objects within the Solar System and beyond.

UTIG Brown Bag: Marcia McNutt (Science)

Title: How Washington Works: A Former Insider's Guide to Navigating our Nation's Capital
Speaker: Marcia McNutt (Former Director, USGS & Editor-in-Chief, Science)

Statoil Lunch & Learn

All students and faculty are invited to have lunch and enjoy a presentation by a Statoil professional on a specialized topic. The title of the talk will be published as soon as it is available.

CIESS Talk: Tom Bogdan (UCAR)

A Conversation with UCAR President Tom Bogdan

UTIG Eminent Scholar Lecture: Marcia McNutt (Science)

Communicating Science: Perspectives from the Trenches
6 pm social hour with lecture following at 7 pm
RSVP to Rosalind Gamble: rgamble@ig.utexas.edu

BEG Friday Seminar: Dr. Jeffrey May, AAPG Distinguished Lecturer 2013

Video Streaming Link: Pending

Dr. Jeffrey A. May
Chief Geologist (Retired)
EOG Resources

*AAPG Distinguished Lecturer 2013
http://www.aapg.org/education/dist_lect/may.cfm

Title: “Mudrock Reservoirs – Why Depositional Fabric & Sequence Stratigraphic Framework Matter”

Abstract:
Mudrocks comprise any deposit with >50% of grains <62 microns in size. Composition, fabric, and texture often are extremely variable. Major influences on these parameters include tectonic setting, source terrane, basin physiography, water depth, circulation and upwelling, oxygenation, climate, eustasy, and detrital influx. Thus, mudrock character – which ultimately controls the distribution and deliverability of hydrocarbons – is anything BUT homogeneous.
Macroscopic core description, tied to stratigraphic framework and integrated with lab analyses and petrophysical interpretation, is critical in understanding variability and deciphering patterns in composition, fabric, and texture. A rich diversity of facies can be discerned. Sedimentary structures such as ripple cross laminae, graded bedding, scour surfaces, rhythmic couplets, and minute burrows to “cryptobioturbation” are common. Stratigraphic variations in these features relate directly to changing depositional conditions and sequence position.
Mudrocks do not simply fill basins passively. Competition between extrabasinal input and intrabasinal biogenic productivity creates conditions for lithologic cycles, clinoform geometries, and water-column stratification. Benthic fauna colonize the seafloor during dysaerobic to aerobic periods, then experience “terror” during periods of mass transport. An understanding of these stratigraphic relationships requires regional correlations that commonly cover thousands of square miles.
Depositional patterns from basins of the Rocky Mountains, Gulf of Mexico, and Canada suggest that mudrock reservoirs are associated with distinct sequence stratigraphic hierarchies. Most prospective mudrock intervals develop during 2nd-order transgressions. In basins with strong extrabasinal sediment influx, the better reservoirs require load-bearing grains and typically form during either 3rd-order highstands or lowstands. By contrast, in basins dominated by intrabasinal biogenic material the best reservoirs often occur in 3rd-order condensed sections. Such units are frequently brittle, with low clay content, high TOC, and abundant microfossils. Thus, the integration of rock description and sequence framework provides better insight into lateral and vertical changes in mudrock character and reservoir targeting.

UTIG Seminar Series: Wes Patterson, John Hopkins University, APL

"Judging a Book by Its Cover: Inferring the Plumbing of Europa’s Icy Shell from Surface Geology"

Abstract:

The Galileo mission to Jupiter and the Cassini mission to Saturn have revolutionized our understanding of icy satellites but have also left us with a number of open questions. From a geologic perspective, the role of cryovolcanism/magmatism in the formation and evolution of icy satellite surfaces is primary among them. On Earth, hydrostatic pressure is capable of bringing mafic and silicic magmas to the surface. For icy satellites, hydrostatic pressure is sufficient to bring icy ‘magma’ to the surfaces of bodies the size of Enceledus but not to bodies the size of Europa. Hence, evidence for cryovolcanism among the icy Galilean satellites has been sparse, while active jetting from the south pole of Enceladus has been observed. Does this mean that the outer ice shells of bodies like Europa harbor, or have harbored, intrusive bodies of water or briney material? More specifically, having only remotely sensed data, is it possible to infer the presence of intrusive/cryomagmatic bodies within the outer shells of icy satellites? Topographic information for two prominently observed morphologies on the Galilean satellite Europa – double ridges and chaos – suggest the answer is yes.

Hydro Brown Bag: Timberly Mayers, DGS

Soft Rock Seminar: Matt Hiatt, EWRE

Movie: Perfect Storms: El Salvador's Ilopango Eruption

For over a decade Dull and Dr. John Southon of the University of California at Irvine have been researching the eruption of Lake Ilopango in El Salvador, and have recently tied the event to what’s known in the scientific community as the “AD 536 Event,” a period of extreme climate change that led to global crop failures, famine and the potentially the first mass outbreak of bubonic plague in the Mediterranean which killed up to 25 million people in Europe.

New evidence uncovered by Dull's research team since 2010 has led him to believe the trigger for the event was the 6th century eruption of Lake Ilopango, a massive caldera volcano located in present day El Salvador.

Part of the Hot Science - Cool Flicks series from the Environmental Science Institute. Q&A will follow the screening.

UTIG Seminar Series: Jacob Walter, Georgia Tech

"Dynamic Behavior of Ice Sheets on Seismic and Slightly Longer Timescales"

Abstract:

A glacier emits seismic waves during a variety of processes like when it undergoes basal stick-slip sliding, calves icebergs, or drains a supraglacial lake. One particularly prominent emitter has been the Whillans Ice Plain (WIP), which may be the most seismically active glacier in the world, in that its bi-daily stick-slip events generate seismic waves observable up to 1000 km away. I will present new field observations from the WIP detailing the rupture process and suggest that the rupture speed may provide not only insight into glacier basal conditions, but basic rupture physics of tectonic earthquakes. Next, I will show that the dynamics at Store Glacier, an outlet glacier in West Greenland, are influenced by ocean tides and the seasonal removal of compacted icebergs and sea ice during the spring. Finally, I highlight the connection between the solid earth and cryosphere by showing that surface waves from distant, large earthquakes, trigger icequakes across Antarctica. The work yields information regarding the sensitivity of ice and tectonic processes occurring on various spatial and temporal timescales. Detailed study of many of these processes is still needed before ice sheet models can realistically forecast ice sheet response to climate forcing.

UTIG Seminar Series: Michael Bender, Princeton University

"Climate of the Last 800 Ka And Beyond Recorded in Ice Cores"

Abstract:
Earth’s climate oscillated between glacial and interglacial conditions with a period of 40 kyr between about 2.8 Ma and 0.9 Ma, and a period of 100 kyr since. Many important climate properties are recorded in ice cores dating to about 130 ka in Greenland and 800 ka in Antarctica. Major results will be summarized, along with efforts to extend the Greenland and Antarctic ice core records to earlier times.

Professional Licensure of Geologists

This is a great opportunity for geology students, faculty and professionals interested in understanding how to become a licensed Professional Geologist in Texas, why it is important, and pertinent information regarding the first step: the Fundamentals Exam.

Lecture by Christopher Mathewson. Hosted by GLOW, Geoscience Leadership Organization for Women. Sponsored by Assoc. of Environmental & Engineering Geologists Texas Section. Lecture at noon, followed by a meet and greet with Dr. Mathewson at 1:00 pm.

Hydro Brown Bag: Dr. Marc Hesse, Faculty, DGS

DGS Awards Ceremony

There will be a reception in the Holland Student Center following the ceremony. All faculty, staff, and students are invited.

Soft Rock Seminar: Charlie Kerans, DGS

The Evolving Integrated Stratigraphic and Structural Framework of the Permian Section, Guadalupe Mts.