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Spring 2018 Colloquia
January 8: Majie Fan, University of Texas-Arlington. Title: Sedimentary record of Eocene-Oligocene elevation and hydroclimate in the central Rocky Mountains
January 15: No Colloquium - Martin Luther King Day
January 22: No Colloquium - Faculty Candidate Search
January 29: No Colloquium - Faculty Candidate Search
February 5: No Colloquium - Department external review
February 12: Bruce Hart, AAPG Distinguished Lecturer Research Scientist, Statoil. Title: Ice Age and the Giant Bakken Oil Accumulation
Abstract: The USGS estimated (2013) that the Late Devonian to Early Mississippian Bakken Formation holds in excess of 7 billion barrels (˜1.1 billion m3) of recoverable oil, making it one of the top 50 largest oilfields in the world. Most of the production comes from shallow-marine sandstones of the Middle Bakken Member that are directly over- and underlain by extremely organic-rich shale source rocks (Upper and Lower Bakken Shale members respectively). Although not oil-productive everywhere, the Middle Bakken forms a relatively sheet-like unit that covers an area of over 200,000 square miles (˜520,000 km2) of the intracratonic Williston Basin.
The vertical juxtaposition of shallow-marine reservoir and more distal source rocks over such a large area, without intervening transitional facies, is unusual from a stratigraphic perspective. One possible explanation would require global fluctuations of sea level to drive geologically rapid and extensive shoreline movements in this relatively stable basin. Forced regression associated with falling sea level could explain the lack of transitional facies (e.g., inner shelf) between the distal Lower Bakken Shale and the overlying Middle Bakken (a sharp-based shoreface). Subsequent sea-level rise would have caused rapid and extensive transgression, leading to the observed stratigraphic relationships between the Middle and Upper Bakken members. But what could have caused the changes in sea level?
A considerable body of evidence points to a Late Devonian-Early Mississippian ice age that covered portions of Gondwana (e.g., parts of present-day Brazil) that were situated close to the paleo South Pole. This ice age consisted of more than one glacial/interglacial cycle and was probably triggered by massive removal of CO2 from the atmosphere by land plants and organic-rich shales. Some evidence indicates that at least 100 m of sea-level drop took place during one of the Famennian glaciations, which would have effectively drained the Williston Basin and induced major shoreline progradation. Melting of the ice sheets would have caused transgression and reflooding of the basin and deposition of the Upper Bakken Shale. Other basins around the world record similar evidence for glacioeustacy near the Devonian-Mississippian transition. The glacial/interglacial cycles are expressed differently from basin to basin, reflecting the interplay between fluctuations of global sea level and each basin’s history of subsidence and sediment supply.
February 13: Marsha French Distinguished Lecturer AAPG Colorado School of Mines. Title: Authigenic Quartz: The Good, The Bad, and The Ugly: Developing a Model for Preserving Porosity in Deep, Hot Sandstone Reservoirs
Abstract:Authigenic quartz overgrowths are the most common pore-occluding mineral in deeply buried (>2500 m) quartzose sandstones. But, deeply buried reservoirs of this kind in the North Sea contain more porosity than expected when the influence of authigenic microcrystalline quartz (microquartz, or the good quartz) is ignored. However, we know relatively little about the nature and origin of this porosity-preserving microquartz, which inhibits the bad and ugly quartz overgrowths from growing and occluding pores. Therefore, advanced analytical techniques have been utilized to improve our understanding of the controls on microquartz development in several examples where porosity is preserved in these and similar sandstone reservoirs.
In this study, several advanced analytical techniques were used to evaluate the crystallographic and compositional controls on the formation of microquartz. SEM/Cathodoluminescence (CL) confirms that (bad and ugly) quartz overgrowths have a complex growth history. Electron Backscatter Diffraction (EBSD) combined with Wavelength Dispersive Spectrometry (WDS) confirmed and elaborated on the complex growth history: the complex banding visible in CL is not due to changes in crystallographic orientation but more likely variations in quartz composition associated with changes in pore fluid composition and/or reservoir conditions. Finally, Secondary Ion Mass Spectrometry (SIMS) analysis provides oxygen isotope data providing insight into those initial reservoir conditions and temperature of formation of microcrystalline quartz.
Integrating the results from these advanced analytical techniques has developed an understanding of the processes controlling the formation of porosity-preserving microquartz and improved our ability to reconstruct the reservoir diagenetic history of microquartz growth leading to a proposed model for predicting porosity preservation in deep, hot sandstone reservoirs.
February 19: Jason Naylor, University of Louisville Title: The Distribution of Severe Weather around Large Cities
Abstract: Large urban areas are known to exert influence on local weather patterns. Noticeable horizontal gradients in temperature and precipitation have been found in and around many metropolitan areas. This talk will focus on the distribution of severe convective events around several large cities, with emphasis on Louisville, KY and Indianapolis, IN. NWS storm-based warnings, local storm reports, and WSR-88D data are analyzed to determine potential locations of enhanced severe weather risk within these cities. A brief history of previous urban weather modification studies will also be presented, along with a discussion of non-meteorological factors that may influence the spatial distribution of warnings and reports.
February 26: No colloquium
March 5: Chris Paola, University of Minnesota. Title: Waves and tides, coasts and shelves: unreasonable experimentation on the banks of the ocean
Abstract: That waves and tides influence the morphology of deltas has been known for decades, but only recently has it become feasible to study these processes systematically under controlled conditions experimentally. For the same energy input waves appear more influential than tides though quantitatively waves smoothing saturates quickly and the two interact such that wave smoothing is strengthened by tides at low wave power. We will then look at the problem of how sand is transported across continental shelves, and evaluate the possibility that true sandy shelf transport systems are shallower than generally thought, and may be better thought of as extended surf zones.
March 12: Spring Break - no colloquium.
March 19: Yolanda Shea, NASA. Title: Unraveling Climate Change Mysteries from Space: The testimony of Earth-reflected radiation
Abstract: An accurate assessment of both how Earth’s climate is changing and which physical processes and feedback are driving those changes requires highly accurate measurements, stable retrieval algorithms, and measurements with sufficient information content. We have used reflected radiance and reflectance as a viable alternative to albedo, and therefore reflected solar irradiance, which provides information about the Earth’s atmospheric composition and surface properties. To gain a better understanding of how we can exploit the wealth of information in spectrally resolved top of atmosphere reflected radiation, we have employed multivariate analysis techniques to quantify the information in such satellite measurements. Information content studies have also illuminated how different accuracy levels impact the amount of information about the climate system available in spectrally resolved reflected solar satellite measurements. Finally, approaching the solution to this problem from a different tack, we have also evaluated the impact of calibration accuracy on cloud property trend detection in an effort to better refine the required stringent calibration uncertainties needed to constrain uncertainties in climate sensitivity and will begin to evaluate satellite retrieval algorithm artifact contributions to uncertainty in climate trend detection.
March 26: Dan Chavas, Purdue University. Title: Using imaginary worlds to understand the tropical cyclone.
Abstract: This talk will discuss the use of planetary climate simulation experiments to understand tropical cyclones on Earth. A hierarchy of models spanning theory, idealized aquaplanet and Earth-like climate simulations, and observations are employed to understand the physical relationship between the two widely-used measures of tropical cyclone intensity: the central pressure deficit and the peak near-surface wind speed. Idealized aquaplanet experiments are then employed to probe fundamental dynamical dependencies of tropical cyclones on a simplified Earth-like planet. The application of these results and their limitations for explaining the rich heterogeneity of real storms on Earth will be discussed.
April 2: Maureen Long, Yale University Title: TBA
April 9: Samantha Hansen, University of Alabama. Title: TBA
April 16:Chen Zhu, Earth and Atmospheric Sciences, IUB
April 23: TBA