Events
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Soft Rock Seminar: Amanda Peralta
Start:November 2, 2015 at 12:00 pm
End:
November 2, 2015 at 1:00 pm
Location:
JGB 3.222
Alumni Reception during GSA in Baltimore
Start:November 2, 2015 at 6:00 pm
End:
November 2, 2015 at 8:00 pm
Location:
Pratt Street Ale House, 206 W. Pratt St., Baltimore, MD
Contact:
Kristen Tucek, ktucek@jsg.utexas.edu, 512-471-2223
De Ford Lecture Series: Nicolas Dauphas, University of Chicago
Start:November 5, 2015 at 3:30 pm
End:
November 5, 2015 at 5:00 pm
Location:
Boyd Auditorium
Contact:
Patrick Stafford, 5124715172
UTIG Seminar Series: Nick Dygert, JSG
Start:November 6, 2015 at 10:30 am
End:
November 6, 2015 at 11:30 am
Location:
PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
Contact:
Nick Hayman, hayman@ig.utexas.edu, 512-471-7721
View Event
“Kinetic Fractionation of Noble Gases beneath Mid-Ocean Ridges: New Insights into Mantle Mixing and Heterogeneity”
Abstract:
Recent measurements have highlighted that the MORB mantle source has distinctly higher 3He/22Ne compared to primitive mantle (~10 vs. 2, respectively) [1]. We seek to understand the source of this difference by modeling chemical exchange between dunite-channel hosted basaltic liquids and harzburgitic wallrock during the percolation of melts to the surface.
Dunite channels are thought to represent pathways for efficient melt extraction from the upper mantle. Percolation of basaltic melts through dunite channels allows them to retain high-pressure multiple saturation depths and the trace element characteristics of their mantle source. However, diffusive interaction of basaltic melts with harzburgite wallrock has an inevitable effect on the chemistry of the lithospheric mantle. In terms of global geochemical cycles, this effect is inconsequential for slow diffusing elements but can be significant for fast diffusiving, incompatible elements. Helium and neon are highly incompatible during mantle melting [2,3] and He is extremely mobile [e.g., 4]. Measurements of He diffusion in olivine suggest it is orders of magnitude faster than Ne at mantle relevant temperatures. Fast diffusion of He out of dunite channel-hosted basaltic melts and into volatile element depleted harzburgitic wallrock can efficiently fractionate He from Ne. These fractionations can then be imparted onto the depleted mantle by subduction or delamination of lithospheric mantle.
Melt percolation-diffusive interaction calculations suggest that preferential 3He ingassing at dunite channels will significantly increase 3He/22Ne of the depleted mantle. Ingassing of peridotite by dunite-hosted basaltic melts has presumably occurred for most of geologic time. This simple model represents an alternative to the multiple degassed magma oceans invoked by [1] to increase the 3He/22Ne of the depleted mantle. If kinetic fractionation is the dominant physical process modulating the 3He/22Ne of the mantle, timescales of mantle mixing on the order of billions of years may be required. Despite seismic tomographic evidence for whole mantle convection, the persistence of low 3He/22Ne reservoirs to the present day requires convective isolation of mantle heterogeneities throughout geologic time.
[1] Tucker & Mukhopadhyay (2014) EPSL 393, 254-265. [2] Heber et al (2007) GCA 71, 1041-1061. [3] Jackson et al (2013) EPSL 384, 178-187. [4] Cherniak & Watson (2012) GCA 84, 269-279.
Grad School Application Q & A
Start:November 6, 2015 at 12:00 pm
End:
November 6, 2015 at 1:00 pm
Location:
JGB 2.112 Career Center
Contact:
Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
Are you applying for graduate school this semester (for Fall 2016 enrollment)? Would you like to discuss the challenges and process with other students and get advice on how to write those statements or your CV?
No need to RSVP, just come on into the Career Center for answers to your questions or discuss with your peers and Career Center staff. We are here to help!
Soft Rock Seminar: Dan Dylward
Start:November 9, 2015 at 12:00 pm
End:
November 9, 2015 at 1:00 pm
Location:
JGB 3.222
Scholar’s Luncheon
Start:November 12, 2015 at 12:00 pm
End:
November 12, 2015 at 2:00 pm
Location:
UT Austin Campus
Contact:
Georgia Sanders, gsanders@jsg.utexas.edu, 512-471-1282
Geology Foundation Advisory Council Meeting
Start:November 12, 2015 at 12:00 pm
End:
November 13, 2015 at 5:00 pm
Location:
UT Austin Campus
Contact:
Georgia Sanders, gsanders@jsg.utexas.edu, 512-471-1282
De Ford Lecture Series: Jean Hsieh, Talisman Energy
Start:November 12, 2015 at 3:30 pm
End:
November 12, 2015 at 5:00 pm
Location:
Boyd Auditorium
Contact:
Patrick Stafford, 5124715172
UTIG Seminar Series: Jolante van Wijk, New Mexico Tech
Start:November 13, 2015 at 10:30 am
End:
November 13, 2015 at 11:30 am
Location:
PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
Contact:
Harm Van Avendonk, harm@ig.utexas.edu, 512-471-0429
View Event
“Initiation, Crustal Architecture, and Extinction of Pull-Apart Basins”
Abstract:
I present a new model for the origin, crustal architecture, and evolution of pull-apart basins. The model is based on results of three-dimensional upper crustal numerical models of deformation, field observations, and fault theory, and it predicts pull-apart rift architecture and temporal evolution that can be tested with field- and geophysical data in future studies. The model is generally applicable to basin-scale features, but predicts some intra-basin structural features. Geometric differences between pull-apart basins are inherited from the initial geometry of the strike-slip fault step, which may, in turn, result from the forming phase of the strike-slip fault system. As strike-slip motion accumulates, pull-apart basins are stationary with respect to underlying basement, and the fault tips propagate beyond the rift basin. Because uplift is concentrated near the fault tips, the sediment source areas rejuvenate and migrate over time. Pull-apart rift lengthening is accommodated by extension within the pull-apart basin as in narrow continental rifts. Field studies predict that pull-apart basins become extinct when an active basin-crossing fault forms; this is the most likely fate of pull-apart basins, because the strike-slip system tends to straighten. The model predicts what the favorable step-dimensions are for the formation of such a fault system, and when a pull-apart basin may further develop into a short seafloor-spreading ridge. The model further predicts that rift shoulder uplift is enhanced if the strike-slip rate is larger than the fault-propagation rate. Crustal compression then contributes to uplift of the rift flank.
Geology Foundation Advisory Council Meeting
Start:November 12, 2015 at 12:00 pm
End:
November 13, 2015 at 5:00 pm
Location:
UT Austin Campus
Contact:
Georgia Sanders, gsanders@jsg.utexas.edu, 512-471-1282
Soft Rock Seminar: Jean Hsieh
Start:November 13, 2015 at 12:00 pm
End:
November 13, 2015 at 1:00 pm
Location:
JGB 3.222
Academic Career Start-Faculty Panel
Start:November 13, 2015 at 1:00 pm
End:
November 13, 2015 at 2:00 pm
Location:
JGB 2.112 A Career Services Conference Room
Contact:
Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
Q&A with distinguished faculty to help PhD students in their quest for an academic career.
This pane: Steve Laubach, Julia Clarke, Wonsuck Kim
No RSVP required
Soft Rock Seminar: Luca Trevisan
Start:November 16, 2015 at 12:00 pm
End:
November 16, 2015 at 1:00 pm
Location:
JGB 3.222
De Ford Lecture Series: Mike Hudec, BEG
Start:November 19, 2015 at 3:30 pm
End:
November 19, 2015 at 5:00 pm
Location:
Boyd Auditorium
Contact:
Patrick Stafford, 5124715172
UTIG Seminar Series: Samer Naif, Scripps Institution of Oceanography
Start:November 20, 2015 at 10:30 am
End:
November 20, 2015 at 11:30 am
Location:
PRC, 10100 Burnet Road, Bldg 196, Rm 1.603, Austin, TX 78758
Contact:
Laura Wallace, lwallace@ig.utexas.edu, 512-471-0324
View Event
“Electromagnetic Imaging of Water-Rich Faults and Melt-Rich Asthenosphere at the Middle America Trench”
Abstract:
Quantifying the flux of water transported by oceanic plates and the distribution of fluids released during subduction is critical to understanding the pattern of seismic coupling at the plate interface and the cycling of water between the solid and fluid Earth. Electromagnetic (EM) methods are ideally suited to map porosity and fluid pathways to help elucidate the hydrogeology of subduction zones. In 2010, Scripps performed the Serpentinite, Extension, and Regional Porosity Experiment across the Nicaragua Trench (SERPENT). We deployed 50 ocean-bottom EM receivers along a 280 km profile that spanned the abyssal plain, trench-outer rise, and forearc slope at the Middle America Trench. In this presentation, I will discuss results from 2-D inversion of both the passive magnetotelluric (MT) and controlled-source EM (CSEM) data.
The MT data led to the surprising discovery of a thin high conductivity channel seaward of the trench at 45-70 km depths. Its resistivity signature requires enough water to induce melting and leads us to conclude the origin of the anomaly to be partial melt.
The CSEM data reveal fluid-rich pathways along bending faults in the incoming crust, the complete subduction of the incoming sediments that define the plate interface, and the migration of fluids from the plate interface to the overlying plate. We infer porosity from resistivity to show that: 1) the incoming crust subducts 60% more pore water than previous estimates, and 2) the subducted sediment porosity decays exponentially, in good agreement with existing compaction studies.
Academic Career Start-Faculty Panel at PRC
Start:November 23, 2015 at 11:00 am
End:
November 23, 2015 at 12:01 pm
Location:
ROC 2.201 Conference Room
Contact:
Maurine Riess, mriess@jsg.utexas.edu, 512-232-7673
Q&A with distinguished faculty to help PhD students in their quest for an academic career.
This pane: Sergey Fomel, Peter Eichhubl, Bayani Cardenas
Refreshments will be provided by the JSG Career Center
No RSVP required
Soft Rock Seminar: Renas I. Koshnaw
Start:November 23, 2015 at 12:00 pm
End:
November 23, 2015 at 1:00 pm
Location:
JGB 3.222
Career Center Open House
Start:November 30, 2015 at 9:00 am
End:
November 30, 2015 at 12:00 pm
Location:
JGB 2.112 Career Center
Last one of the semester! Free bagels & coffee
Soft Rock Seminar: Breecker Group
Start:November 30, 2015 at 12:00 pm
End:
November 30, 2015 at 1:00 pm
Location:
JGB 3.222
MG&G Field Course Presentation DayMay, 30 2025Time: 10:00 AM - 12:00 PMLocation: ROC 1.603 Each Maymester, the University of Texas Institute for Geophysics (UTIG) offers a field course designed to provide hands-on instruction for graduate and upper-level undergraduate students in the collection and processing of marine geological and geophysical data. The course covers high-resolution air gun and streamer seismic reflection, CHIRP seismic reflection, multibeam bathymetry, sidescan sonar, sediment coring, grab sampling and the sedimentology of resulting seabed samples (e.g., core description, grain size analysis, x-radiography, etc.). Scientific and technical experts in each of the techniques first provide students with several days of classroom instruction. The class then travels to the Gulf Coast for a week of at-sea field work and on-shore lab work. Two small research vessels are used concurrently: one for multibeam bathymetry, sidescan sonar, and sediment sampling, and the other for high-resolution seismic reflection and CHIRP sub-bottom profiling. Students rotate daily between the two vessels and lab work. Upon returning to Austin, students work in teams to integrate data and techniques into a final project that examines the geologic history and/or sedimentary processes as typified by a small area of the Gulf Coast continental shelf. Students spend one week learning interpretation methods using industry-standard, state-of-the-art software (Focus, Landmark, Caris, Fledermaus). On the last day, students present their final project to the class and industry sponsor representatives. |