Spring 2013 Colloquia

January 7: No colloquium, first day of the semester

January 14: Tudor Lecture, Terry Engelder, Penn State University

January 21: Martin Luther King Jr. Day, no classes

January 28: John Rakovan, Department of Geology and Environmental Earth Science, Miami University, Oxford, Ohio. Title: Environmental Mineralogy of Apatite: Funtamental Mechanisms of Metal Sequestration, with Applications in Radionuclide Waste Disposal and Containment Remediation

February 4: Kathy Benison, West Virginia University. Topic: Environmental/Low-temperature geochemistry

February 11: Dr. Benjamin Gill~ Department of Geosciences, Virginia Tech Title: "University Ocean Ventuilation Recorded by Sulfur Isotopes During the Late Ordovician Extinction"

February 18: Enrique Merino, IU Bloomington Department of Geological SciencesTitle: Self-organized genesis of karst geomorphology by terra rossa/bauxite formation and the reactive-infiltration instability.

Abstract: The geochemical dynamics of terra rossa formation may trigger a morphological water-rock instability able to yield the self-organized set of sinks that is characteristic of karst landscapes.

February 25: Barbara Tilley, University of Alberta. Title: Isotope Systematics of Mature Shale Gases

Abstract: Isotope geochemistry is now recognized as a tool for shale gas exploration. Its utility however depends on an understanding of the isotope systematics for the particular region of interest as well as for shale gas maturation in general. Isotope data for Barnett and Fayetteville shale gas (Zumberge et al., 2012), fractured reservoirs and shale gas in the Appalachians (Burruss and Laughrey, 2010; Baldassare, 2011, Molgat et al., 2011) and fractured reservoirs and shale gas in the WCSB (Tilley et al., 2011; Tilley and Muehlenbachs, 2012, and unpublished data) provide a framework within which shale gases can be evaluated and better understood in terms of their general evolution. Compilation, review and re-interpretation of these data show that shale gases can be classified into three distinct maturation stages that have unique and distinctive carbon and hydrogen isotopic relationships and trends. Identifying the maturation stage of a gas can lead to a better understanding of the processes that have occurred and may help predict the ultimate productivity of a shale gas play.

March 4: Lindsay McHenry, University of Wisconsin at Milwaukee. Title: The minerals of Olduvai Gorge: implications for stratigraphy, paleoanthropology, and Mars geology.

March 11: No Colloquium, Spring Break

March 18: Carlos Jarimillo, Smithsonian Tropical Resarch Institute in Panama. Title: Title: "A Geology History of Netropical Rainforests"

Carlos is a paleobotanist and geologist who has worked on topics ranging from the origin of neotropical ecosystems to the origin of the landmass of Central America itself. He specializes in late Mesozoic and early Cenozoic new world paleofloras and geology, but has published on topics ranging from graphical correlation, to eustatic events in the early Cenozoic, to the closing of the Isthmus of Panama. more

March 25: No Colloquium

April 1: Matt Pritchard, Cornell. EarthScope Distinguished Lecturer. Title: "Towards a pixel-by-pixel view of North America’s changing surface using geodetic imaging." Mat’s work focuses on application of state–of–the–art remote sensing techniques (mostly radar interferometry) to analyze Earth deformation associated with earthquakes, volcanoes, and glaciation.

Abstract: For centuries, measurement of the shape of the Earth (called the science of geodesy) was necessarily time consuming. Even with new technologies like the Global Positioning System (GPS), vast portions of the Earth remain infrequently monitored for movement. Recently, a new form of geodesy has rapidly developed whereby image pairs can be compared to infer movements of the Earth’s surface. Called geodetic imaging, the synoptic aircraft or satellite views allow large regions to be surveyed densely without any human setting foot in the area. Imaging geodesy encompasses several different types of methods including Interferometric Synthetic Aperture Radar (InSAR) as well as the automated comparison of SAR and optical images via pixel tracking. InSAR can image sub–centimeter deformation of the Earth’s surface every 1–20 meters over areas spanning hundreds to thousands of kilometers. Pixel tracking is a very complementary tool to InSAR; although the sensitivity to deformation is less (decimeter instead of sub–centimeter in a given image pair) and the horizontal spacing is coarser, it can be applied to both radar and optical images and often works when InSAR does not – for example, in areas that have large displacements or changes to the radar scattering properties of the ground. InSAR has allowed vast areas of the Earth’s surface to be monitored frequently for deformation for the first time and this presentation will highlight some of the discoveries in North America and elsewhere, selected with input from the host institution. Possible topics include earthquakes/tectonics, magmatic processes in the Basin & Range and globally, landslides, glaciers (especially in Alaska), groundwater, changes in vegetation, and human–induced ground deformation. A US InSAR mission was part of the original Earthscope plan. While the US InSAR mission (currently called DESDyni–R) is not likely to launch until 2019, Earthscope (along with NASA and others) has facilitated access to InSAR data over North America from several foreign satellite missions from 1992–present. There will soon be more than 300 Terabytes of raw SAR imagery available through UNAVCO and the Alaska Satellite Facility. Most of this data is from the Japanese ALOS mission which had a radar wavelength of 23 cm that is capable of making coherent interferograms over most of North America for the first time. This presentation will discuss how to get access to that data, how to set up a processing capability, and what types of problems this data can and cannot be used to address. Interferograms of the host institution will be presented.

April 8: Dr. Lev Spivak–Birndorf, Indiana University Department of Geological Sciences Title: "Extinct Radionuclides in the Early Solar System: The Initial Solar System Abundance of 60Fe from Angrites and Unequilibrated Ordinary Chondrites."

Abstract: The presence of a number of extinct radionuclides in the early Solar System (SS) is known from geochemical and isotopic studies of meteorites and their components. The half–lives of these isotopes are short relative to the age of the SS, such that they have now decayed to undetectable levels. They can be inferred to exist in the early SS from the presence of their daughter nuclides in meteoritic materials that formed while they were still extant. The extinct radionuclides are particularly useful as fine–scale chronometers for events in the early SS. They can also be used to help constrain the astrophysical setting of the formation of the Sun because their short half–lives and unique formation environments yield information about the sources and timing of delivery of material to the protoplanetary disk. Some extinct radionuclides are considered evidence that the Sun interacted with a massive star (supernova) early in its history.

The abundance of 60Fe in the early SS is particularly useful for constraining the astrophysical environment of the Sun’s formation because, if present in sufficient abundance, its only likely source is injection from a nearby supernova. The initial SS abundance of 60Fe is poorly constrained at the present time, with estimates varying by 1–2 orders of magnitude. I present an investigation of the 60Fe–60Ni isotope systematics of ancient, well–preserved meteorites using high-precision mass spectrometry to better constrain the initial SS abundance of 60Fe. These new estimates of the initial abundance of 60Fe from both differentiated basaltic meteorites (angrites) and from components of primitive chondrites that formed in the Solar nebula suggest a lower initial 60Fe abundance than has been reported by some recent studies.

April 12: Dr. Li Dong, Los Alamos National Laboratory Title: "A first look at MPAS atmospheric dynamical core in AMPI simulations."

Abstract: The Model for Prediction Across Scales (MPAS) is a new climate model that has the potential to perform regional climate simulations within the framework of global modeling. In this talk, I will briefly introduce this model and compare it with the traditional regional climate models (RCMs). Then I will show some preliminary AMIP simulations of general circulations by MPAS as well as simulations of a regional atmospheric feature – the Great Plains Low Level Jet.

April 15: Craig Manning, UCLA. PRIMSM Lecture. Title: In deep water: new insights into geologic fluids of the deep crust and upper mantle Slides (PDF)

April 22: Steven Desch, Arizona State University. Title: The Sun formed in a large cluster: Short-lived radionuclides in the meteoritic record.

Abstract: Multiple lines of evidence, both from analyses of meteorites and from astronomical observations, indicate that the Sun formed in a large cluster with many thousands of stars, including at least a few massive stars that carved out an H II region with their ionizing radiation and then exploded as supernovas. In this isotope-themed talk I will present the evidence from isotopic analyses of meteorites that the early solar system contained short-lived radionuclides (SLRs) with half-lives on the order of 1 Myr, and I will discuss astrophysical models for their origins. My modeling suggests that 10Be has an origin as trapped Galactic Cosmic Rays, energetic particle irradiation within the solar nebula was probably responsible for 36Cl and certain LiBeB isotopic anomalies, but that other SLRs like 41Ca, 26Al and 60Fe must have originated in a nearby supernova. I will present my models of supernova injection into disks and molecular clouds. Injection into the molecular cloud matches meteoritic constraints and should also be a common event in the birth of Sun-like stars born in such star formation environments.

April 23 Steven Desch, Arizona State University. Title: The Sun formed in a large cluster: Star formation and protoplanetary disk processes.

Abstract: Multiple lines of evidence, both from analyses of meteorites and from astronomical observations, indicate that the Sun formed in a rich cluster with many thousands of stars, including at least a few massive stars that carved out an H II region with their ionizing radiation and then exploded as supernovas. In this astrophysics-oriented talk I will discuss the observational evidence that most Sun-like stars form in such regions, and present our combined HST/Spitzer observations that provide strong evidence for triggered star formation in such environments. I will then provide evidence from our solar system's architecture that our protoplanetary disk experienced photoevaporation due to intense far-ultraviolet radiation originating from massive stars in a rich cluster. My modeling suggests that the radial transport in the disk and subsequently planet formation may be strongly influenced by external photoevaporation and therefore by the star formation environment.

April 29: No colloquium, exam week