Axel K. Schmitt; Laacher See revisited: High-spatial-resolution zircon dating indicates rapid formation of a zoned magma chamber. Geology ; 34 7 : — Laacher See Germany phonolite eruption. Thus, LLST zircons shortly predate the eruption and yet are not strictly part of the phonolite crystallization sequence. Based on their similarity to zircons in subvolcanic nodules, they are instead interpreted to be scavenged from a precursor syenite intrusion, which implies short a few k. Shibboleth Sign In. OpenAthens Sign In. Institutional Sign In. Sign In or Create an Account.
Kenneth L. Pierce
Daniel E. Karig, a Todd S. Copyright remains with the author s or their institution s. Permission for reuse free in most cases can be obtained from RightsLink.
My research is in the field of Quaternary Geology and Geomorphology. to the Yellowstone Plateau and Tetons: Geological Society of America Field Guide 10, p. J.C., Jr., and Pierce, K.L., , Creation of the Teton Landscape, a Geological , Obsidian hydration dating of Quaternary events, in Noller, J.S., Sowers.
Geological Survey, 5 University of Nebraska-Lincoln. Eolian sediments cover vast areas of the North American midcontinent fig. An increasing interest in eolian sediments and associated soils as climate proxies has spurred several recent studies of Quaternary loess and eolian sand in the region Muhs et al. Loess, eolian sand, and volcanic ash deposits provide direct records of atmospheric circulation that can be used to test atmospheric general circulation models Muhs et al.
A proliferation of studies over the last two decades have given us an appreciation of the dynamic nature of eolian landscapes, and the complex linkages among geologic, climatic. Figure –Map of the midcontinental United States showing thickness of Peoria Loess and field-trip stops. Adapted from Bettis, Muhs, et al. On this trip, we will visit loess localities in western Iowa and eastern Nebraska fig. The thick loess bordering the Missouri River valley has a long history of investigation dating back to the late ‘s.
Recent studies at several localities have yielded new insights on several aspects of the region’s loess and eolian record, most notably the chronology and sources of the loess. Some of the data in this guidebook are derived from previous studies reported in Bettis, Mason, et al. A detailed treatment of the trip area’s Cenozoic stratigraphy is beyond the scope of this guidebook. Presented here are salient elements of the region’s eolian stratigraphy that relate to localities visited on this trip.
Extensive wind-deposited tuffaceous silts and sands with interbedded tuff occur in the wedge of Paleogene and Neogene sediment extending eastward from the Rocky Mountain Front Range across the western Great Plains.
Bacon is a geologist with over 20 years of experience specializing in field investigations associated with the application of basic and applied research in Quaternary geology, geomorphology, and engineering geology related to terrain and geotechnical-site characterizations, landscape evolution, paleoclimate studies, geologic hazards, and archaeological investigations.
Recent basic research has focused on the characterization of alluvial, fluvial, and lacustrine depositional environments using geomorphic mapping, sequence stratigraphy, soils, and 14 C and OSL analyses, plus hydrologic modeling within the arid southwestern United States to infer latest Pleistocene and Holocene hydroclimate variability.
Recent applied research has included geomorphic-based predictive terrain modeling of mobility and dust emission hazards for military operations in desert regions, as well as geomorphic characterization of alluvial fan environments for flood hazards. Past field areas that involved studying landscape evolution in alpine to desert environments related to geologic hazards or paleoclimate research include the western U.
Bacon, S. Geologic and geomorphic record of late Pleistocene and Holocene lake levels of Owens Lake, eastern California.
Dating fluvial terraces by Th/U on pedogenic carbonate, Wind River Basin, Volume 59, Issue 2; March , pp. Geological Society of America Bulletin , (). Ku, T.-L., Bull, W.B., Freeman, S.T., and Knauss, K.G. Th— U dating of pedogenic carbonates in gravelly desert soils of Vidal Valley, southern.
Below is a comprehensive list of publications by BGC scientists. Included are publications by current BGC Faculty arising from prior affiliations elsewhere. If you would like to order reprints email. For reprints, please indicate the full citation including author. Dygert N. Goehring, B.
My research interest is to study paleoclimate changes during the last deglaciation through examining loess-paleosol, dune-wetland, and lacustrine-marl successions in mainly Illinois, United State. The objectives of my research are 1 to establish intra-chronozonal climate records at places progressively moving towards the retreating ice margin of the Laurentide Ice Sheet; 2 to understand biogeochemical cycles in these successions for paleoclimate proxy studies.
I use radiometric conventional and accelerator mass spectrometry AMS radiocarbon and optically stimulated luminescence OSL dating technologies for chronology study and use stable isotope geochemistry and other geochemistry and geophysics techniques for developing proxies. Dune-wetland succession at the Manito site in the middle Illinois River Valley and Loess-paleosol succession at the Keller Farm site in the middle Mississippi River Valley reveal climate changes on intra-chronozonal levels.
Top two panels show the Manito dune site and proxy results and bottom two panels show Keller Farm loess and Bon Harbor proxy only loess sites in Mississippi and Ohio River Valleys through collaborating with Kentucky Geological Survey.
Mississippi Valley-type lead-zinc deposits through geological time: Implications from recent age-dating research. DL Leach, DC Bradley, MT RE Wells, ML Miller. Geological Society of America Bulletin (7), , ,
Our program has had a long emphasis on undergraduate research as part of their professional development. Below are some of the associated outcomes. Todd, Multiple glacial tills in an exposure along the lower Elkhorn River, Nebraska. Blair A petrographic analysis of potsherds from Tell Hisban, Jordan. Engelhardt , In depth analysis of a portion of the Thetis Regio Highland Region on Venus; a critical comparison of proposed upwelling and downwelling models for highland plateau formation.
Jonsfhorded, Spitsbergen using microstructural analysis and preferred orientations of Tuttle lamellae in quartzites and quartzarenites. Geology Student Research.
The Marcy massif was metamorphosed to granulite facies conditions, in places preserving igneous textures with metamorphic coronas and is most deformed near its margins. Historically, the relationship between anorthosite emplacement and metamorphism has been controversial, and many workers have argued that anorthosite emplacement coincided with metamorphism. This study presents new in-situ geochronology that constrains the timing of metamorphic mineral growth in Adirondack anorthosite to — Ma.
The Zr source for metamorphic zircon growth was the breakdown of hemoilmenite and is texturally linked to high-pressure mineral assemblages. These data are consistent with previously determined ca.
Geology can also include the study of the solid features of any terrestrial planet or natural satellite such as Mars or the Moon. Modern geology significantly overlaps all other earth sciences , including hydrology and the atmospheric sciences , and so is treated as one major aspect of integrated earth system science and planetary science.
Geology describes the structure of the Earth on and beneath its surface, and the processes that have shaped that structure. It also provides tools to determine the relative and absolute ages of rocks found in a given location, and also to describe the histories of those rocks. Geology provides the primary evidence for plate tectonics , the evolutionary history of life , and the Earth’s past climates.
Geologists use a wide variety of methods to understand the Earth’s structure and evolution, including field work , rock description , geophysical techniques , chemical analysis , physical experiments , and numerical modelling. In practical terms, geology is important for mineral and hydrocarbon exploration and exploitation, evaluating water resources , understanding of natural hazards , the remediation of environmental problems, and providing insights into past climate change.
Geology is a major academic discipline , and it plays an important role in geotechnical engineering. The majority of geological data comes from research on solid Earth materials. These typically fall into one of two categories: rock and unlithified material. The majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth.
There are three major types of rock: igneous , sedimentary , and metamorphic. The rock cycle illustrates the relationships among them see diagram.
Publications by BGC scientists
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Duties include sample analysis, data reduction, isotopic standards development and preparation, research support for collaborating scientists and students, and data publication. Teaching Assistant : Field geology: worked with students to create geologic maps and reports. Gave lectures and graded maps and reports. Metamorphic petrology: gave lectures and led laboratory assignments so that students could identify and understand metamorphic processes.
Geochronology and isotope tracers: led discussions and graded homework and tests to improve student grasp of isotope geochemistry and dating techniques. Earth Materials: taught students to identify rocks and the processes by which they were formed. Field work included sample collection, structural and textural data collection. Teaching Assistant : Taught two or three introductory geology laboratories per semester, meeting three hours per week, and covering a broad variety of introductory topics.