[IGPP Everyone] [EPSS Everyone] Spring Colloquium

[MANNING, CRAIG E]

Dear EPSS,
As you head off for spring break, know that you can look forward to a terrific lineup of Spring colloquium speakers when you return. Details below. I look forward to seeing you Tuesday afternoons next quarter.
best
Craig


Fred Ciesla, University of Chicago  (April 3, 2018)

Title: Chemical and Dynamical Evolution of Dust in the Solar Nebula

Abstract: The early stages of planet formation involve the coagulation of sub-micron dust that was suspended in the solar nebula into larger aggregates, which themselves come together to form the building blocks of the planets.  During this stage of growth, dust grains and the bodies in which they are contained are subjected to a number of dynamical processes which caused them to migrate significant distances from where they first formed.  Evidence for this redistribution is readily found in the meteorite record, with chondritic meteorites made of individual components that record very different formation conditions.  This transport will expose dust grains to a variety of environments which will drive chemical and physical evolution of the dust grains.  I will present results which allow us to begin understanding the feedbacks between dynamical and chemical evolution within the solar nebula, and how these effects may be seen in the meteorite record as well as planet-forming disks around other stars.

Kevin McKeegan, UCLA (April 10, 2018)

Title: Twenty-Five years of SIMS at UCLA


Paul Santi, Colorado School of Mines  (April 17, 2018)

Title:  Debris Flows Following Wildfire in the Western U.S.

Abstract: The frequency, intensity, and areal extent of wildfires in the Western United States are increasing.  Changes imposed on watersheds during and after burning result in a dramatic increase in debris-flow occurrence and magnitude, which in turn poses risks to human life and property, especially as the urban-wildland interface advances into mountainous areas.  Flows can be initiated following wildfire by low intensity rainfall events, and they grow substantially in volume through channel scour while in transit.  On average, flow volumes are 3-5 times larger immediately after wildfires, and the volume magnification effects linger for 1-3 years before the watershed recovers. Volume is difficult to predict accurately, but it can be estimated using multiple linear regression models that rely on GIS-friendly inputs such as area burned, rainfall totals, and watershed slope characteristics.  A new probabilistic model has been shown to be more accurate and it relies on even fewer terms.  Discharge rates and velocity are also difficult to predict, so reasonable ranges are derived using databases of previous field measurements.  Damming and avulsion of the flows make runout patterns unpredictable, but recent studies have helped to quantify the process.

Ed Young, UCLA  (April 24, 2018)

Title: TBD


Brett Gladman, University of British Columbia  (May 1, 2018)

Title:  TBD


Linda Elkins-Tanton, Arizona State University  (May 8, 2018)

Title: NASA Psyche Mission: Journey to a Metal World

Abstract: The Psyche mission has been selected as the fourteenth in the NASA Discovery program. This mission will investigate what is likely an exposed planetary metallic core, the asteroid (16) Psyche. Orbiting the outer main belt at ~3 AU, the asteroid as an effective diameter of ~235 km and is thought to be made almost entirely of Fe-Ni metal. In this talk I’ll present the science will do at Psyche, the design of the spacecraft and instruments, and the operations plan at the asteroid.


George Hilley, Stanford University  (May 15, 2018)

Title: A Limit on Earth’s Topography Revealed by Channel Steepness in Tropical Granitic Landscapes

Abstract: Rivers determine the maximum elevation of most tectonically active mountain belts, control the coupling between climate and tectonic processes, and archive the pace and tempo of fault-related rock uplift rates. Long-profiles of rivers in steep, non-glaciated landscapes are thought to be controlled by the bedrock incision rate, leading many to posit that channel discharge and slope determine the pace of river incision (hereafter referred to as the power-law incision rule).  We tested the power-law incision rule in watersheds varying by four orders of magnitude in erosion rate (4.7 x 10-3 - 7.1 mm/yr mm/yr), and combined these with a global analysis of erosion rates and topography.  Our data and analyses reveal that this rule breaks down in steep, rapidly eroding landscapes, in which river profiles reach a threshold steepness that is invariant in steep watersheds.  This limit to the steepness of channels suggests the present and past overall topographic relief on Earth may be limited by the horizontal extent of active rock uplift, with higher relief resulting from longer channels of a given steepness, rather than the rate of uplift itself.

Anne Pommier, UC San Diego  (May 22, 2018)

Title: Experimental Investigation of Core Crystallization in Small Terrestrial Bodies

Abstract: Core crystallization is a crucial ingredient in the evolution of terrestrial bodies and is controlled primarily by chemistry and temperature. Crystallization within a metallic core releases latent heat and gravitational energy, influencing significantly the processes responsible for the presence of a magnetic field. The diversity of magnetic fields observed in small terrestrial bodies, such as Mars, Mercury or Ganymede suggests different core cooling history. Past missions have observed that Mars does not currently possess an internally-generated magnetic field but likely had one early in its history, while Mercury currently possesses a weak magnetic field and Ganymede is characterized by a strong one. The origin of this diversity is not well understood and seems to depend highly on the onset, depth, and rate of crystallization. This presentation will focus on the effect of chemistry on core crystallization and its implications for the magnetic field. Phase equilibria and electrical experiments on core and core-mantle analogues have been conducted in the Fe, Fe-S, Fe-S-O and Fe-S-Si (+/- olivine) systems using the multi-anvil apparatus at conditions relevant to the core of small terrestrial bodies (pressure up to 20 GPa and temperature up to 1850°C). The effect of sulfur and oxygen on core crystallization from melting relations will be discussed in terms of light element distribution and core compositional stratification.  Laboratory-based electrical resistivity-crystallization models will be used to provide insight regarding the insulating properties of chemical heterogeneities that result from core crystallization or mantle-core interactions. All results will be compared to the magnetic history and available observational constraints on the core structure, temperature and composition of Mars, Mercury and Ganymede.

Bethany Ehlmann, California Institute of Technology  (May 29, 2018)

Title: TBD


Leila Hamdan, University of Southern Mississippi  (June 5, 2018)

Title: Stowaways: Using shipwreck microbiomes to study spill impacts and dispersal in in the deep-sea

Abstract: There are ~2,000 historic shipwrecks in the Gulf of Mexico spanning 500 years of history. Shipwrecks become artificial reefs and islands of biological diversity. Residues from the Deepwater Horizon Spill were deposited on the seafloor in areas where historic shipwrecks are present.  The spill creates potential for contact of oil with shipwreck remains and the biological communities on and around them. These interactions may impact the preservation of historic shipwrecks. Accordingly, this study examined the spill’s lasting effects on microbiomes surrounding 7 historic shipwrecks. The study included steel-hulled World War II-era and wooden-hulled 19th century shipwrecks. Through comparative analysis of 16S rRNA sequence libraries from wrecks located within and external to the spill’s seafloor footprint, this study documented that the German U-boat U-166 and the sailing vessel known as Mardi Gras were exposed to deposited oil.  The work also provided opportunity to examine the effect that shipwrecks have on microbiome diversity. A shipwreck may be an oasis for diversity, and assist transport of microorganisms across the seafloor. Sediment cores were collected along 200 m transects at 2, and 25 m intervals away from the wrecks, using Jason-style push corers or an instrumented MC800 deep-sea multicorer. Shannon diversity and species richness were highest near the shipwrecks, and declined as a function of distance. Bray-Curtis similarity revealed that community composition was distinct in samples near the wrecks vs. away from them. Communities were organized by distance, and secondarily by depth. This study indicates that deep-sea microbiomes are shaped by shipwreck ‘island habitats’.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.igpp.ucla.edu/pipermail/everyone/attachments/20180324/73394d11/attachment-0001.html>
-------------- next part --------------
_______________________________________________
Everyone mailing list
Everyone at dept.epss.ucla.edu
http://dept.ess.ucla.edu/mailman/listinfo/everyone