Geology Open Night

The Enigmatic Pebbly Loess   Gil Hanson 7:30 PM Friday Feb. 15, 2019 ESS 001 Earth-science-education student researchers at Stony Brook University have found that much of the undisturbed areas of Long Island are covered with loess. Generally, loess is tan well sorted, wind-blown silt with minor sand and clay. Long Island loess, however, has pebbles. Dominguez, 2015, however, found that pebbly loess was not well sorted. Instead, it is an unsorted sediment, a diamict. This is consistent with the findings of Clare, 2013, who showed that pebbly loess has the same grain-size characteristics as the underlying till. Kundic, 2005, dated the deposition of the pebbly loess to be about 13,000 years ago. Tvelia, 2015, found that pebbly loess in Rocky Point contains charcoal, magnetic spherules, carbonaceous spherules and scoria-like objects (melted rock). These data are consistent with extensive, forest fires and the impacts of fragments of a comet or asteroid at about 13,000 years ago during the Younger Dryas (12,900 to 11,500 years ago) when the climate returned to near glacial conditions (Wolbach et al, 2018a, and 2018b).  Earth-science-education student researchers at Stony Brook University have found pebbly loess in Suffolk, Nassau and Westchester counties. They found that the pebbles are dominantly quartz and are typically 1 cm in diameter but may be up to 5 cm in diameter. In their research they are also considering whether the characteristics of the soil developed on pebbly loess influence whether deciduous forests or pine barrens occur in undeveloped areas. Carolina bays are abundant features along the Atlantic Coastal Plain including Suffolk County. They are elliptical to circular-shaped, shallow depressions with closed rims and flat bottoms. In Rocky Point Tvelia, 2015, found pebbly loess in the area surrounding the Carolina bays as well as in the rims and flat interior. This suggests that the pebbly loess and Carolina bays have a common origin. Dr. Hanson is a distinguished service professor in the Department of Geosciences. He has been interested in the geology and environmental problems of Long Island for the last couple of decades. Earth science education students, earth science teachers, and MS in Geosciences students carried out most of this research.

Interpreting the Rock Record: Reconstructing the formation conditions of meteor craters on Earth.   Lars Ehm 7:30 PM Friday Mar. 8, 2019 ESS 001 Impact cratering is recognized as an important process in the formation and evolution of planetary bodies, which relies upon complex aggregation, collision and ejection processes between planetesimal materials and planetary surfaces. Impactites and meteorites provide a record of these high-impact processes, where we can determine the conditions of the impact and provide experimental constraint for the models of planet formation from the primordial solar nebular. Remnants of the shock conditions are preserved in the irreversible changes in rocks and minerals on the macroscopic, microscopic and atomic scale. Over the past 30 years, detailed investigation of the microstructure of shock mineral and mineral aggregates of impactites and meteorites as well as of experimentally shocked minerals have allowed us to infer the peak pressure and temperature conditions during the impact from a combination of petrographic signatures, mineralogical phase transitions and the occurrence of high pressure polymorphs in the impactite or meteorite. We will explore a new type of experiments that aims to simulate meteorite impact using the world’s most powerful X-ray sources and how the newly gained information helps us to reconstruct the conditions at which impact craters formed. Lars Ehm is an Associate Professor in the Department of Geosciences at Stony Brook University. His research focuses on understanding the structure-property relationships in minerals and Earth materials at extreme environmental conditions. Dr. Ehm received his Doctorate Degree from Christian-Albrechts-University Kiel, Germany. He was a Postdoctoral Fellow at the Geophysical Laboratory of the Carnegie Institution of Science in 2003-2005. In 2005 Dr. Ehm joint Stony Brook Universities’ Mineral Physics Institute, first, as a Postdoctoral Associate and later transitioned into a Research Faculty position with a joint appointment at Brookhaven National Laboratory. He joint the Department of Geosciences in 2018 as an Associate Professor.

Indoor Seismology: From Elasticity of Minerals to Mantle Composition and Dynamics   Baosheng Li 7:30 PM Friday April 12, 2019 ESS 001 Seismological studies provide the most direct information about the structure and properties of the Earth's deep mantle where direct access is prohibited by the extreme conditions of pressure and temperature. By measuring compressional and shear wave velocities of mantle minerals under high pressure and temperature in the laboratory, the seismic wave velocities of candidate mineralogical models along mantle geotherm can be constructed and their comparisons with seismic data can provide constraints on the radial and lateral variations of chemical composition, temperature, and/or water content. In this presentation, the current state-of-the-art experimental study on multi-phase synthetic “rock” by using ultrasonic interferometry in conjunction with synchrotron X-radiation will be introduced. In addition, by using updated elasticity for mantle minerals and their high pressure phases, velocity and density profiles for pyrolite model will be compared with seismic models from upper mantle to the bottom of the lower mantle. Lastly, the lateral heterogeneities of the lower mantle will be evaluated for possible thermal anomalies and chemical variations. Dr. Li’s research is aimed at understanding the composition and dynamical processes of the Earth’s interior by conducting experimental and computational studies on minerals and rocks at extreme pressure and temperature conditions. Research activities in experimental studies involve the use of ultrasonic interferometry, X-ray diffraction and imaging, Infrared and Raman spectroscopy, scanning electron microscopy (SEM), electron probe microscopic analysis (EPMA), multi-anvil high pressure apparatus, and diamond anvil cells. Dr. Li also conducts first principles calculations to complement and help further understand the observed experimental results. Dr. Li is the pioneer of the technique of ultrasonic sound velocity measurement in multi-anvil apparatus at high pressure and high temperature.

 

You may also be interested in the following lectures: Astronomy Open Night, The World of Physics and The Living World These lectures are usually held in ESS 001 at 7:30 p.m. on Fridays during the academic year.