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September 1, 2017
0:00am in PLS 1130
Barbara Cohen from NASA Goddard Space Flight Center
The Violent Early Solar System, as Told by Planetary Sample Geochronology

Abstract: 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. I 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.

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September 15, 2017
3:00pm in PLS 1130
Michelle Minitti from Framework
Side-walking along Mars: Gale Crater’s Pahrump Hills as seen by MARDI

Abstract: The Mars Science Laboratory Curiosity rover landed on Mars in August, 2012 to seek habitable environments recorded in the rocks of Gale Crater. The ultimate target for this exploration is a 5-km tall mound within Gale informally known as Mt. Sharp. Curiosity encountered the basal unit of Mt. Sharp, the Murray formation, at the Pahrump Hills outcrop, and systematically explored it in a series of progressively more detailed campaigns, from reconnaissance to sampling. The Mars Descent Imager (MARDI), mounted on the underside of Curiosity to fulfill her primary job of recording the rover’s descent to the Martian surface, was uniquely positioned to record the terrain traversed by Curiosity during the reconnaissance campaign. By continually acquiring images during each drive of the reconnaissance campaign, MARDI produced a sidewalk-like mosaic of the Pahrump Hills terrain. The mosaic, a continuous record of sedimentary and diagenetic features within the dominantly mud- to siltstone bedrock, contributed to the interpretation of the Pahrump Hills as a lacustrine deposit. Since departing the Pahrump Hills, MARDI has continued to record the characteristics of the Murray formation as Curiosity traverses up the flank of Mt. Sharp. This systematic imaging has extended the lacustrine interpretation to the Murray formation beyond the Pahrump Hills, while revealing changes over time in the depositional conditions of the Gale crater lake that yielded the Murray formation.

September 22, 2017
3:00pm in PLS 1130
Kelsey Young from NASA/Jacobs Technology Inc.
The Integration of Field Portable Instruments into Planetary Surface Exploration

Abstract: 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 crewmember 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.

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September 29, 2017
3:00pm in PLS 1130
Diane McKnight from NSF
Glacial meltwater streams in the McMurdo Dry Valleys, Antarctica: ecosystems waiting for water

Abstract: 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.

October 13, 2017
3:00pm in PLS 1130
Lina Echeverría from Corning Incorporated (Vice President of Science and Technology, Retired); Innovation Leadership Consultant
The Unpredictable Arc of a Career In Geology

Abstract: 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 intellectual property in corporate America, and on to understanding the creative drive of individuals and harnessing it to deliver technology innovations.

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October 20, 2017
3:00pm in PLS 1130
Emily Martin from Smithsonian Institution
Exploring the tectonic histories of Saturn's ocean worlds: from deep time to now.

Abstract: 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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November 3, 2017
3:00pm in PLS 1130
Sarah Johnson from Georgetown University
Searching for Life on Mars and Distant Moons

Abstract: Advances in molecular biology have the potential to alter the way we look for life in solar system, from direct detections to a deeper understanding of how biology affects patterns of mineralization. This talk will discuss our ongoing research into biosignature detection, including work in planetary analog environments like Australian acid salt lakes and the Dry Valleys of Antarctica. It will explore how handheld sequencers are starting to change the way we do remote field work, and how one day they may transform biological observation of the most inaccessible places on Earth, just as remotely telemetered image data revolutionized our understanding of the planet at the dawn of the Space Age. The talk will conclude with possibilities for nanopore-based life detection, including a concept that harnesses the power of sequencing to fingerprint patterns of surface chemical complexity as signatures of life, regardless of whether that life is based on nucleic acids.

November 10, 2017
3:00pm in PLS 1130
Hélène Le Mével from DTM/Carnegie Institution for Science
Geodetic measurements and numerical models of volcanic unrest at large silicic systems

Abstract: I will examine the ground deformation associated to non-eruptive unrests at two volcanic systems: the Laguna del Maule volcanic field (Chile), experiencing high uplift rates since 2007, and the Long Valley caldera (USA), experiencing multiple episodes of surface uplift over the last 40 years. I will present results from analytical and numerical models to interpret these episodes of ground deformation in terms of magmatic processes.

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November 17, 2017
3:00pm in PLS 1130
Matthew Kohn from Boise State University
Shear heating controls mineralogy, seismicity, and convection in subduction zones

Abstract: Popular thermal-mechanical models of modern subduction systems are c. 300 °C colder at c. 50 km depth – the seismic-aseismic transition – than pressure-temperature conditions determined from exhumed metamorphic rocks, i.e. "Rocks are hotter than models” (Penniston-Dorland et al., 2015, EPSL). Subduction zone thermal structure is crucial for predicting depths of seismicity, fluid release, and sub-arc melting conditions. In this talk I will show that adding realistic shear stresses to thermal models quantitatively reproduces surface heat flow and the pressure-temperature conditions recorded by exhumed metamorphic rocks. A consistent seismic-aseismic transition depth of c. 50 km, however, is difficult to explain through mineralogical or thermal weakening mechanisms. Rather, I propose that mechanical removal of rheologically weak and buoyant rocks along the subduction interface leads to seismic decoupling and dynamic coupling between slab and mantle to drive mantle wedge convection and arc volcanism.

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The coordinator for the Colloquium Series is Dr. Nicholas Schmerr. You can contact him at