September 7, 2018
3:00pm in PLS 1130
Alan Brandon from University of Houston
Constraints on Crustal Contamination of Martian Shergottite Magmas

Abstract: For 3 decades, a debate over whether shergottite meteorites with incompatible trace element enriched compositions were the result of crustal contamination while their parent magmas migrated to the surface or instead represent a mantle source in Mars, has not been resolved.  There is now enough compositional data for shergottites to model the process of crustal contamination of possible parent magmas in order to resolve this debate.  This talk will present the results of these models with implications to the origins of shergottite magmas in Mars.

September 14, 2018
3:00pm in PLS 1130
Kei Shimizu from Carnegie DTM
Carbon contents in Earth's mantle domains constrained using silicate melt inclusions and geochemical modeling

Abstract: Estimates of carbon contents in mantle sources of mid-ocean ridge basalts (MORBs) and ocean island basalts (OIBs) can provide constraints on the origin of the geochemically heterogeneous mantle. Furthermore, carbon fluxes from MORB and OIB mantle sources to the atmosphere provide constraints for understanding Earth’s climate stability and habitability. However, carbon contents in these mantle sources are difficult to estimate since most MORBs and OIBs have lost significant portions of their CO2 through degassing. Silicate melt inclusions, which are small amount of quenched magma trapped in crystals, preserve the CO2 contents in MORB and OIB magmas at depths of melt inclusion entrapment prior to significant CO2 degassing. In this talk, I will discuss carbon contents for MORB mantle sources (Siqueiros and Garrett transform fault in the East Pacific Rise) and a component of an OIB mantle source (Borgarhraun in northern Iceland) estimated using data from silicate melt inclusions in combination with geochemical modeling of mantle melting, magma degassing and mixing. The preliminary results suggest that at least one component of the Iceland mantle source (~400 ppm CO2) may be significantly more carbon-rich compared to an EPR-type MORB mantle source (~100 ppm CO2).

September 21, 2018
3:00pm in PLS 1130
Dalia Kirschbaum from NASA Goddard
Finding the Slippery Slope: “Detecting” Landslides from Space

Abstract: Rainfall-triggered landslides occur in nearly every country around the world, causing billions of dollars of damages and cause thousands of fatalities each year. Understanding and modeling the dynamics of rainfall-triggered landslides is a challenging task due to rainfall variability and the complexity of approximating landslide failure mechanisms over broader scales. Satellite data provides a unique perspective to estimate where and when landslides may be occurring as well as to map areas when these events occur. However, the accuracy is highly dependent on the spatial scale and methods used. This presentation outlines several on-going efforts to better understand landslide activity at different spatial and temporal scales using different modeling, mapping and citizen science methods.

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September 28, 2018
3:00pm in PLS 1130
Amanda Lindoo from Carnegie Geophysical Laboratory
Permeability development in ascending magmas: implications for explosive vs. effusive eruption styles

Abstract: Transitions in volcanic eruptive style in mafic magmas are poorly understood. While silicic systems are the most researched and publicized due to their explosive character, mafic volcanoes remain the dominant form of volcanism on the earth. Eruptions are typically effusive, but changes in flow behavior can result in explosive, ash generating episodes. The efficiency of volatiles to degas from an ascending magma greatly influences eruption style. It is well known that volatile exsolution in magmas is a primary driving force for volcanic eruptions, however the roles vesicles and syn-eruptive crystallization play in eruption dynamics are poorly understood. Because the merging of bubbles in magma is mitigated by melt viscosity, it is predicted that permeability development in mafic magma will occur at lower bubble volumes than in silicic magma. However, no study has been performed on experimental samples to provide evidence for this hypothesis. Furthermore, it is unknown how microlites affect the degassing process in terms of facilitating or hindering permeability development. In this talk I will describe how experimental petrology can be employed to: 1) experimentally observe how melt viscosity alone affects permeability development in magmas and 2) understand the effects of syn-eruptive crystallization in vesiculating mafic magmas. Then I will apply our experimental findings to the 2008 eruption of Kasatochi volcano, AK.

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October 5, 2018
3:00pm in PLS 1130
Jane Willenbring from Scripps Institution of Oceanography, UC San Diego
The Null Hypothesis: steady rates of erosion, weathering and sediment accumulation during Late Cenozoic mountain uplift and glaciation

Abstract: At the largest time and space scales, the pace of erosion and chemical weathering is determined by tectonic uplift rates. Deviations from this equilibrium condition arise from the transient response of landscape denudation to climatic and tectonic perturbations, and may be long lived. I posit that the constraint of mass balance, however, makes it unlikely that such disequilibrium could persist at the global scale over millions of years, as has been proposed for late Cenozoic erosion. In this talk, I will use the available data to discuss the possibility that erosion, weathering fluxes and shelf sediment accumulation have remained constant over the last ten (or more) million years. Two important implications are: (1) global climate change may not change global denudation rates, because the nature and sign of landscape responses are varied; and (2) tectonic and climatic perturbations are accommodated in the long term by changes in landscape form. This work undermines the hypothesis that increased weathering due to late Cenozoic mountain building or climate change was the primary agent for a decrease in global temperatures.

October 19, 2018
3:00pm in PLS 1130
Gene Likens from Cary Institute of Ecosystem Studies
November 2, 2018
3:00pm in PLS 1130
Kristen Fauria from Woods Hole Oceanographic Institution
November 9, 2018
3:00pm in PLS 1130
Christine M Hartzell from Department of Aerospace Engineering, UMD
November 16, 2018
3:00pm in PLS 1130
Michelle Bensi from Department of Civil and Environmental Engineering, University of Maryland, College Park

The coordinator for the Colloquium Series is Dr. Mong-Han Huang. You can contact him at mhhuang@umd.edu.
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