Category Archives: UMD

University of Maryland geology department

UMD: Martin on Saturn’s moons

2017 University of Maryland Geology Colloquium Series

Friday, October 20th 2017 at 3:00 pm
in PLS 1130, UMD College Park

Emily Martin
Smithsonian Institution

Exploring the tectonic histories of Saturn’s ocean worlds: from deep time to now.

Observations of Enceladus’s tectonic structures suggest that Enceladus may have expereienced punctuated episodes of tectonic activity. Similar populations of fractures on Dione and Rhea may also preserve evidence of varied stress histories within the fracture patterns expressed on their surfaces. Similarities and differences of the preserved fracture histories on these will inform the complex tectonic histories and geologic activity on these ocean worlds.

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UMD: Echeverría on Geology Careers

2017 Geology Colloquium Series

Friday, October 13th 2017 at 3:00 pm
in PLS 1130, University of Maryland – College Park

Lina Echeverría
Corning Incorporated (Vice President of Science and Technology, Retired); Innovation Leadership Consultant

The Unpredictable Arc of a Career In Geology

Upbeat after the completion of postdoctoral and academic research, it feels safe to assume that life will continue along a straight road not unlike those lived by professors and colleagues who have surrounded us for close to three decades. This is particularly so when the experiences—college, graduate, post doc and beyond—have brought exploration and discoveries and, with them, excitement. From Buddhist philosophy we learn that life is what happens when we are busy making plans—and our clear plans may have surprising turns. As unexpected doors open in our lives, that same curiosity and willingness to venture of our early career will lead us into new territories, allow for contributions, and recreate excitement in totally unknown fields. We just have to be prepared to be surprised. Illustrating this narrative, I will share my career and life experiences, the unexpected turns from spinifex komatiites to the world of research and in! tellectual property in corporate America, and on to understanding the creative drive of individuals and harnessing it to deliver technology innovations.

UMD: NSF’s McKnight on Dry Valleys ecosystems

2017 University of Maryland Geology Colloquium Series

Friday, September 29th 2017 at 3:00 pm
in PLS 1130, UMD College Park

Diane McKnight
NSF

Glacial meltwater streams in the McMurdo Dry Valleys, Antarctica: ecosystems waiting for water

The McMurdo Dry Valleys of Antarctica is comprised of alpine and terminal glaciers, large expanses of patterned ground, and permanently ice-covered lakes in the valley floors, which are linked by glacial meltwater streams that flow during the austral summer. These valleys were first explored by Robert Scott and his party in 1903. In 1968 the New Zealand Antarctic Program began a gauging network on the Onyx River, a 32 km river that is the longest river in Antarctica. As part of the McMurdo Dry Valleys Long-Term Ecological research project, our research group has continued to monitor streamflow in the Onyx River and 15 other first-order streams in adjacent valleys. We have studied the linkages between hydrology, biogeochemistry and microbial community ecology in stream ecosystems through a period of climatic extremes. We found that the diatom community composition in the mats that are abundant in the streams varies with the flow regime. In the 1990! ’s a cooling period continued that was driven by atmospheric changes associated with the ozone hole. In the summer of 2001/002, this cooling period was interrupted by several warm and sunny summers that created “flood events” in the valleys and caused much greater ecological connectivity. During floods the microbial mats are scoured from the streambed and mat material is transported to the closed basin lakes. Thus, understanding the relationship between mat communities and hydrology may help in using diatoms preserved in lake sediments and perched deltas to reconstruct the hydrologic record beyond the limited instrumental record of the Dry Valleys.

UMD: Kelsey Young on The Integration of Field Portable Instruments into Planetary Surface Exploration

2017 University of Maryland Geology Colloquium Series

Friday, September 22nd 2017 at 3:00 pm
in PLS 1130

Kelsey Young
NASA/Jacobs Technology Inc.

The Integration of Field Portable Instruments into Planetary Surface Exploration

While the six Apollo lunar surface missions were successful in returning samples to Earth and developing a better understanding of lunar geologic history, the next generation of crewed planetary surface exploration will seek to develop a deeper understanding of the Inner Solar System. New and higher-resolution technology will enable future human crews to rapidly and in real-time collect and interpret geochemical and geophysical data, whether it is on the Moon, Mars, or an asteroid. These technologies not only have applications in planetary exploration but also in industry and mining, as any in situ tool rapidly increases the rapid and real-time capabilities of the user. This flexibility is crucial in instrument development, as any crew member will seek to deploy these technologies in a number of different capacities during long-duration spaceflight. This presentation focuses on the multiple uses of field portable instrumentation, its incorporation into NASA operational field tests, and how ongoing field campaigns seek to evaluate the operational concepts for using in situ analytical capabilities in future exploration.

UMD: Cohen on early solar system events

2017 Geology Colloquium Series

Friday, September 1st 2017 at 3:00 pm
in PLS 1130, the University of Maryland at College Park

Barbara Cohen
NASA Goddard Space Flight Center

The Violent Early Solar System, as Told by Planetary Sample Geochronology

One of the legacies of the samples collected by the Apollo and Luna missions is the link forged between radiometric ages of rocks and the timing of major geologic events, such as impact cratering. Our current understanding of the chronology of the inner solar system is based on the Moon, where evidence suggests that intense bombardment happened during planet formation, followed by a relatively quiescent period, and increased again in an extraordinary bombardment event (“cataclysm”) in the Earth-Moon system at ~3.9 Ga. The importance of the age of lunar samples goes far beyond assigning stratigraphic markers to lunar chronology. The temporal evolution of lunar bombardment is tied to the evolution of a habitable Earth, while the flux of impactors at the Moon drives dynamical models of the formation of the inner solar system. Dr. Cohen will discuss how we use the geochronology of lunar and meteorite samples to understand the past history of impact events on the Moon, the Earth, and throughout the solar system.

UMD Geology: Zhang on Fe-Ni-S-C Liquid in the Earth’s Mantle

2017 University of Maryland Geology Colloquium Series

Friday, April 7th 2017 at 3:00 pm
in PLS 1140 (College Park campus)

Johnny Zhang
Scripps Institution of Oceanography

Fe-Ni-S-C Liquid in the Earth’s Mantle

Fe-Ni-S-C phases are accessory phases in the Earth’s mantle, but carry important geochemical and geophysical implications due to the contrasting physical and chemical properties between metallic and silicate phases. In the shallow mantle (<200 km), the metallic phase occurs as monosulfide solid solution (mss) or melt with near-monosulfide stoichiometries. To constrain the sulfide melt stability field and its Fe-Ni exchange with mantle silicate minerals, we performed experiments at comparable conditions (P, T, fO2) to Earth’s shallow mantle. In the deeper part of the upper mantle (200-410 km), the mantle become reduced, corresponding to an increase of metal activities in sulfide melt. To contain the composition of Fe-Ni-S melt and its storage of deep carbon, we performed experiments and thermodynamic calculations to show the evolution of Fe-Ni-S-C compositions and mantle silicates at deep upper mantle conditions. Based on the experim! ental and modeling exercise, further discussion will be made on the recent Fe-Ni-S-C liquid from deep diamonds (Smith et al. 2016). In the deepest part of Earth’ mantle (<2900 km), we propose that small quantities of Fe-Ni-S-C liquid is the cause for the two large low shear velocity provinces (LLSVPs). These Fe-Ni-S-C liquid is likely trapped during the crystallization of a dense basal magma ocean and therefore a potential carrier of primordial geochemical signature.

UMD: Viete on metamorphism as earthquake record

2017 Geology Colloquium Series

Friday, March 31st 2017 at 3:00 pm
in PLS 1140, University of Maryland, College Park

Daniel Viete
Johns Hopkins University

Metamorphism can record individual earthquake events in the subduction setting: evidence from the Franciscan Complex, California

Rhythmic major-element zoning has been documented in garnets from high pressure/low temperature (HP/LT) lenses within a number of worldwide subduction mélanges (e.g. California, Chinese Tianshan, Cuba, Greek Cyclades, Guatemala, Japan, Venezuela). These features reflect some fundamental process(es) in the subduction setting. In this talk, conditions of rhythmic zoning acquirement in HP/LT garnets of the Franciscan Complex, California are investigated by use of thermodynamic modeling of phase equilibria, and Raman and synchrotron Fourier transform infrared (FTIR) microspectroscopy.

Hornblende, omphacite and zoisite in the Franciscan rocks are also complexly zoned in major elements. Modeling of phase equilibria shows that modal contours for garnet, amphibole and zoisite are gently dipping in the P–T region that corresponds to the peak-metamorphic mineral assemblage. Metamorphic assemblage diagrams suggest that hydration/dehy! dration reactions involving garnet <—> zoisite (which also involve amphibole exchange or omphacite for glaucophane) are incredibly sensitive to changes in P (e.g. 5–10 vol.% absolute gain/loss of garnet for ΔP = 250 MPa). Major-element zoning in the Franciscan minerals may record repeated growth–partial dissolution cycles in response to P fluctuations in the subduction setting.

Quartz-in-garnet Raman barometry reveals varying P—on the order of 100–350 MPa, over radial distances of 10s of µm—in association with the major-element zoning in the Franciscan garnets. Results from synchrotron FTIR microspectroscopy demonstrate association between zone overgrowths and OH in garnet (a proxy for crystallization pressure in pyrope garnet). The microspectroscopy results confirm changes in P attended development of the rhythmic garnet zoning.

Steep compositional gradients defining the rhythmic major-element zo! ning limit time scales at peak T (and garnet growth–dissolution) conditions to < 1 Myr, requiring that individual growth–partial dissolution cycles were extremely brief. Overpressure on the order of 100s of MPa can develop by tectonic loading of the crust and is relieved with earthquake rupture. Seismic cycles represent ephemeral phenomena capable of accounting for development of rhythmic major-element zoning in HP/LT garnet, during subduction, as a result of fluctuations in P (and garnet stability). Metamorphic rocks may carry detailed records of the catastrophism that punctuates longer-term tectonometamorphic processes.