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Branson Field Laboratory
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.jpg) Surface-water geochemistry |
 Collecting Geoprobe well data |
 Measuring strikes and dips |
.jpg) Structures in metamorphic & igneous rocks |
 Seismic refraction analysis
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Overview & Regional Geology
Our intent at the Branson Lab is to have you solve substantive problems in as many different geological settings as is possible in six weeks. Therefore, most of our projects are short, one to three days in length, but as the outcrop exposures are excellent, we spend our time on the rocks instead of looking for outcrops. Our emphasis is on fieldwork as contrasted to field trips, and you should expect to spend most of your time on foot in the field. However, we also believe it is important that you understand the regional context of the field exercises. To this end, we give you instruction on the regional geology of Wyoming and follow this with a 4-day camping trip through northwestern Wyoming and adjacent parts of Idaho and Montana. On this trip we see some of the classic geologic features of Wyoming and explore the great variety of tectonic styles and rock types present in northwestern Wyoming. The features we see include: block faulting in the Grand Tetons, thrust faulting in the Hoback Canyon, the volcanic rocks and recent normal faulting in the Snake River plain, volcanic rocks and thermal features of the Yellowstone plateau, the spectacular alpine glacial features of the Beartooth pass, and exotic blocks associated with the Heart Mountain detachment.
Introduction & Techniques
Our field projects are graduated to lead you progressively through the processes involved in field mapping and to expose you to progressively more complicated field settings. During the first week of camp, we introduce basic field techniques including: use of the Brunton compass, measurement of stratigraphic sections, recording of field notes and field data. You start to learn the local stratigraphy and how to identify the formation units you will encounter in several of the mapping exercises.
Sedimentation & Stratigraphy
Next, we study sedimentary rocks in Mesozoic and Tertiary clastic strata and in Paleozoic carbonate strata. We instruct you in the methods of facies analysis, and you apply these methods by recording bed shapes, sedimentary structures, textures, and mineralogy of the formations to identify environments of deposition. Many different facies are present: shallow marine, fluviatile, eolian, etc. Students turn in graphic logs of the stratigraphic units and short written reports.
Structural Geology and Geologic Mapping
Our projects in structural geology are done in three different areas that are gradational in their complexity of folding, faulting and tectonic history. The early projects involve structural analysis in folded and faulted sedimentary rocks; the latter projects include analysis in deformed metamorphic rocks intruded by granitic plutons (see "hard rock" geology discussed below). You learn to use GPS receivers and to map in the field on enlarged topographic maps and orthophoto aerial photographs. The orthophotos are of the same scale and projection as the topographic maps, so you can overlay the two and recognize the coincidence of topography and the photographed surface features. Final maps are compiled on the topographic bases or may be completed digitally on digital base maps in our computer lab. You can expect to draw several cross sections as a means of interpreting the geology that you map. The intent of our projects in structural geology is to teach you how to make geological maps, and how to interpret them as historical records and as three-dimensional portrayals of earth structure. No matter how you end up applying your geology degree, an ability to visualize both surface and subsurface features in three dimensions is critical. These exercises are designed to give you the background you need to develop three-dimensional perspectives.
Hard-Rock Geology
Our projects in "hard rock" geology are done at elevations of 7000 to 8000 feet in the historic region of South Pass, Wyoming. Here, on excellent outcrops of folded Archean plutonic and metamorphic rocks, you collect data that allow you to establish the structural, metamorphic, and intrusive history of the area. You map the distribution of granitic and metamorphic units cut by mafic dikes. You learn to portray and analyze the data, including foliation, lineation and fold orientations, on geological maps and fabric diagrams. The analyses involve both hand plotting and computer plotting of fabric data to determine the geometry of regional folding and its relationship to the Precambrian metamorphic and igneous units in the area.
Environmental Geology
For many of you, your ultimate field applications will be in the area of environmental geology. In order to give you background in this area, we include a project on surface water and ground water monitoring. The objective of the project is to learn about the interaction between surface water and ground water and their relationship to the near subsurface geology. The project includes: 1) installation of shallow monitoring wells and core recover using a Geoprobe(TM), truck-mounted coring devise, 2) installation of piezometers to produce a map of the local water table, 3) variable head (slug and bail) tests to estimate horizontal hydraulic conductivity, 4) sampling of stream and groundwater and measuring field pH, alkalinity, dissolved oxygen, hardness and sulfate with portable meters and chemical testing kit, 5) stream gauging, and tracer monitoring to determine surface and groundwater interactions, and 6) a shallow seismic refraction survey to correlate subsurface geology with well cores.
We recently presented information and procedures that we use for this project at an annual meeting of the Geological Society of America. The abstract for our presentation and a link to view or download our poster presentation are available by clicking this line.
Advanced Hydrogeology or Geophysics Projects
Students who have completed at least an introductory course in hydrogeology or geophysics may elect to complete a week of more advanced projects in either of these topics. You will work closely with Don Siegel and Laura Lautz of Syracuse University on the hydrogeology project or with Eric Sandvol of the University of Missouri on the geophysics project.
Students working with Siegel and Lautz on hydrogeology will
investigate the interface between surface water and ground water. One
study site will be "Dry Lake", a small water body that appears to be a
regional groundwater discharge point in what otherwise is a dry valley.
Dry Lake, in fact, is never dry! The studies here will integrate the
hydrogeological , limnological, and geochemical characterization of the
site and its relationship to local geologic structures that you mapped
in earlier projects.
The second focus will be more intensive work in Red Canyon Creek, where
students, depending on the streamflow conditions, will map stream
geomorphology and tie it into local inseepage and outseepage of ground
water into the creek. The seepage will be identified by direct
measurements all along a section of the creek. In this part, you may
also do more extensive tracer tests, learned during the main
Environmental Project, to compare and contrast different parts of the
stream system hydrology. As part of this effort, you may also do an
aquifer test and evaluate how solutes move in the subsurface by
measuring concentrations of introduced chloride over time.
Students working with Eric Sandvol on the geophysics project will
acquire and use of high resolution
seismic reflection profiles to locate and characterize ground water flow
in Red Canyon. The Mesozoic and Paleozoic sedimentary rocks in Red
Canyon, combined with the dry environment, allow for the efficient
propagation of high frequency P-waves. Students will determine the
maximum depth at which reasonable signal to noise is maintained and
determine the maximum resolution of the reflection images using
different sources and receiver configurations. Students will experiment
with different acquisition designs to determine which might work best.
Data processing will be accomplished with field lap top personnel
computers and the desktops located in the field camp’s computer lab. The
students will learn how to determine optimal band-limiting filters,
apply normal move-out corrections and static corrections, and to
identify and mute out surface waves. This kind of basic processing
should be sufficient to produce high quality Common Depth Point stack (CDP)
image of the upper 200 meters. This level of processing does not require
an extensive geophysics background and should be appropriate for all
students.
The high-resolution seismic images acquired during the project allow you to effectively map the depth to ground water surface over a large area beyond what is possible using only well log data. This will be accomplished by correlating the depth to groundwater as determined from the Geoprobe well logs. Similarly students will correlate reflection horizons with stratigraphic units measured from the well logs. This will be done in the field camp's computer lab using standard seismic data processing packages (WinSeis). The exercise will demonstrate how to integrate independent field measurements and develop a model for groundwater flow over a much larger area than would have been possible without the seismic data. The exercise will allow both students and instructors to test hypotheses about ground water flow and the stratigraphy of the upper 200 meters of rock.
