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Department of Geology
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Department of Geology, University of MarylandSpring 2010 Seminar Series 11:00am - 12:00pm Coffee and tea are served in the Geology Building at 10:30am prior to the seminar. Friday February 5 Nora Noffke, Old Dominion University "Turbulent lifestyle: Cyanobacteria on Earth's sandy beaches - today and 3 billion years ago" Abstract: Cyanobacteria are photoautotrophic microorganisms that are very well adapted to the harsh hydraulic conditions of sandy tidal environments. The microorganisms form large, carpet-like microbial mats that significantly affect the prevailing physical sedimentary dynamics of waves and currents. If deposited by sediment, the mobile microbes move towards the new depositional surface, however, during periods of high erosive stress, we can observe biostabilization. This microbial-physical interaction originates characteristic sedimentary structures that are termed ‘microbially induced sedimentary structures (MISS)’. Examples are ‘multidirected ripple marks’, ‘erosional remnants and pockets’, ‘oriented grains’, and many others. The structures do not resemble stromatolites, but form an own group. MISS occur not only today, but they are abundant in shallow-marine sandstones of all Earth ages. Because the oldest structures were found in early Archean rock successions, we can compare them with those we find today along our present coasts. Therefore, the MISS constitute valuable tools for the reconstruction of Earth’s earliest life. A recently detected stratigraphic section in the 2.9 billion years old Archean Pongola Supergroup, South Africa, includes exceptionally preserved microbial mat-related structures. Those stuctures record microbial mats of the same types like those colonizing the tidal flats of the North Atlantic ocean today. Most probably, the microbial mats of the Pongola Supergroup include the oldest known cyanobacteria in Earth's history. Because the preserved microbiota are highly divers, this finding suggests a much earlier start of evolution of cyanobacteria than assumed before.Friday February 12 John Sharp, The University of Texas at Austin "Deep and Wide: Implications from Studies of Carbonate Systems in Mexico" Abstract: Cuatrociénegas and Zacatón are important karstic systems in Mexico. Cuatrociénegas is a world famous environmental system threatened by economic development. Its springs harbor a unique biotic assemblage. Our findings show that the springs are fed by a large, interbasin karstic system that that is still poorly understood, but that management will require a regional approach. Zacatón is formed by hypogene processes associated with Pleistocene volcanism that deposited extensive travertines and formed large phreatic cenotes (pozas). One of the pozas, El Zacatón, is perhaps the world's deepest phreatic shaft that was mapped to ~317 meters depth by the DEPTHX robot. Calcite “lids”, detected by electrical resistivity, isolate large underlying water-filled voids. The recognition of analogous systems in Turkey and Australia implies that this volcanogenic (hypogene) karstification is not unique. Analyses of deep karstic systems may have to extend wider and deeper than is common for both scientific analyses and water resources management. Friday February 19
Paul Marinos, National Technical University of Athens, Greece "Geology of Athens, Greece: A case of urban geology for land use, construction of major engineering structures, hazard assessment and sustainable development" Friday February 26 NO SEMINAR Friday March 5 NO SEMINAR Friday March 12 Ethan Baxter, Boston University "Making a Long Story Short: Brief Pulses During Regional Metamorphism" Friday March 19 NO SEMINAR Friday March 26 Mark Little, USGS/GSA Congressional Science Fellow "TBA" Friday April 2 Anna Courtier, James Madison University "Hot or not? Mantle temperature and composition beneath ocean islands" Friday April 9 Gray Bebout, Lehigh University "Metamorphic Records of Subduction-Zone Devolatilization, Element Mobility, and Chemical/Isotopic Hybridization" Friday April 16 TBA "TBA"
The coordinator for the Colloquium Series is Dr. Sarah Penniston-Dorland. You can contact her at sarahpd AT umd.edu |