Eocene Tectonic Evolution of the Tetons-Absaroka Ranges, Wyoming
What: Structural geology of Laramide and Heart Mountain detachment deformation
When: mid-July to mid-August
Where: Northwest Wyoming (Cody and Jackson)
Who: John Craddock (Macalester College) and Dave Malone (Illinois State University) plus 6 students
Northwest Wyoming is a unique field location where the overlap, in space and time, between the Sevier thin-skin (Cretaceous-late Paleocene) and Laramide (late Cretaceous-Eocene) thick-skin orogens can be observed. Contemporaneous with these orogens is the collapse of the Eocene Sunlight volcano, forming the world’s largest debris avalanche and low-angle normal fault detachment, the Heart Mountain detachment. The S. Fork detachment chaos is part of the Heart Mountain system southwest of Cody.
Potential Student Projects
Finite strain study of a footwall fold in the Cambrian Flathead Sandstone (quartzite) overthrust by Archean gneisses (S. Tetons).
Calcite twinning strain study of the footwall fold in lower Paleozoic carbonates overthrust by Archean gneisses (N. Tetons).
Structural geology and geochemistry (XRF, detrital zircons) of vertical microbreccia “injectites” at White Mountain, Heart Mtn. detachment.
Structural geology and geochemistry (XRF, detrital zircons) of vertical microbreccia “injectites” proximal to White Mountain, Heart Mtn. detachment.
Structural geology and mapping of the rootless, folded S. Fork detachment (10 x 40 km; 2 students), with likely detrital zircon geochronology.
Logistics/Special Field Conditions
We will be camping and in the field most of the month with backpacking required for the 2 projects in the Tetons. The daily hiking can be strenuous and involves lots of topography.
Interdisciplinary studies in the Critical Zone, Boulder Creek catchment, Front Range, Colorado
Keck Colorado group in the Green Lakes basin, highest of the three study catchments.
What: The Keck Colorado 2011 project will work with a large interdisciplinary study (Boulder Creek Critical Zone Observatory: Weathered profile development in a rocky environment and its influence on watershed hydrology and biogeochemistry-NSF 0724960) directed by Suzanne Anderson, Institute for Arctic and Alpine Studies (INSTAAR), University of Colorado. The Keck Project focus is measurement and sampling of geologic deposits and processes in the critical zone, “the heterogeneous carapace of rock in various stages of decay, overlying soil, and the ecosystems they support… fundamental characteristics of the critical zone, such as its thickness, the character of the weathered rock and soil layers and the biological activity within them, together control the passage of water, the chemical processes operating, the material strength, and the function of subsurface ecosystems.” The “observatory” consists of 3 small, instrumented sites in the Boulder Creek basin: (1) Green Lakes Valley-a steep, glaciated alpine area in the Boulder watershed where “fresh” materials are exposed at the surface; (2) Gordon Gulch-a forested, mid-elevation catchment developed in weathered materials, and (3) Betasso-a steep, lower-elevation basin where surficial deposits are of variable thickness.
When: July 13-August 10
Where: Middle Boulder Creek catchment, Colorado Front Range
Who: David Dethier (Williams College) and 3 students with assistance from Matthias Leopold (Technical University of Munich)
Project overview and goals
General goals of the Keck Colorado Project include making field measurements and collecting samples to help characterize the critical zone and its development, geochemistry and hydrology, and gaining hands-on experience with field geophysical techniques used to investigate the shallow subsurface down to fresh bedrock. Broader research questions include:
“How does soil development and chemistry vary across erosional and ecological regimes in the study area?”
“How does the distribution of critical zone development control the hydrologic response of the catchments to both snow and rainfall?”
“How do weathering and nutrient fluxes vary across the study catchments?”
“How does land-use history, including mining and deforestation, impact critical-zone processes in the two lower-elevation sites?”
“How fast is sediment transported on hillslopes and in the channels of the study catchments
Students and project faculty will collect data and/or solid or liquid samples at field sites. We will work on laboratory preparation and initial sample treatment at MRS or at the extensive analytical facilities at INSTAAR in Boulder. I expect that participants will return to their home schools with field data, initial results of some laboratory measurements and samples ready for additional analysis. Data from geophysical (after post-processing) and geochemical analyses (as necessary) will probably return sometime in the fall semester. Analysis and interpretation of field and laboratory results at the home institution will be supervised by the student’s advisor and aided by the Project Director. Potential student projects include:
Characterizing the chemistry of shallow groundwater and meltwater near late-lying snowfields in Green Lakes basin and/or from baseflow in deeply weathered areas.
Using synoptic sampling of stream chemistry to help study weathering rates in Gordon Gulch.
Measuring local variations in rock strength and erodibility using Schmidt hammer techniques.
Mapping the depth to bedrock and the structure of the shallow subsurface in Gordon Gulch using resistivity and ground-penetrating radar techniques.
Measuring variations in soil morphology, chemistry, sediment generation and transport processes along slope transects from ridge crest to channel using field, geochemical and cosmogenic radionuclide (CRN) techniques.
Comparing the coupling between hillslope erosional processes, channel morphology and sediment transport in Betasso and Gordon Gulch using cosmogenic radionuclide (CRN) techniques.
Collecting a core for studies of Holocene climate change and mercury deposition, N. Boulder Creek, Colorado
We’ll be at elevations ranging from 5,000 to 12,500 feet and working in environments from the hot semidesert to late-lying snowfields and summer hailstorms! Participants will stay at an elevation of 9500 ft at the University of Colorado’s Mountain Research Station on the shoulder of Niwot Ridge and within hiking distance of the Green Lakes site. Cabin accommodations are rustic but they’ll serve us well! Nederland, the nearest town, is about 20 minutes to the south. The Boulder urban area is about an hour away. The Lab has a research building with a library, a few computers and wireless connections. We’ll have breakfast and dinner 5 days a week at the dining hall and we’ll make bag lunches to take to the field. We’ll make other arrangements for Saturdays and Sundays!
Important for the fourth year of this interdisciplinary project is a strong interest in surface and near-surface processes and in interdisciplinary science, a record of hard work and the ability to follow through. We would prefer gregarious, “can-do” students with a background in geology or physical geography and coursework in:
Mineralogy and/or geochemistry
Geomorphology or Quaternary geology or hydrology
Sedimentology and/or soils (valuable)
Field mapping, structural geology, geophysics or (valuable)
GIS or a strong background in supporting science (useful)
The Hrafnfjordur central volcano, Northwestern Iceland
Composite satellite image of Iceland showing the Westfjords and location of study area.
What: Field and laboratory research on Tertiary volcanic rocks in the Westfjords region of northwestern Iceland. The main research focus is the Hrafnfjordur central volcano, where we expect to encounter both basalts and rhyolites, and likely some intermediates. The project will consist of three weeks of field study in Iceland, and one week of laboratory follow-up at The College of Wooster (Ohio). Students will continue research during the following academic year.
When: July 10-August 7
Where: The Westfjords region of northwestern Iceland, and The College of Wooster (Wooster, Ohio)
Who: Six students
Project faculty: Brennan Jordan (University of South Dakota) and Meagen Pollock (The College of Wooster)
Project Overview and Goals
The 103,000 km3 island of Iceland has been produced by geologically continuous volcanism over the last 15 million years. The robust volcanism of Iceland is the result of the intersection of the Mid-Atlantic Ridge with a hotspot, generally interpreted as a mantle plume. The focus of rifting within Iceland has shifted several times during its history. A widely accepted model for the tectonic evolution of Iceland is: the mid-ocean ridge system drifts to the west relative to the hotspot, and Icelandic rifts are abandoned as they drift off of the hotspot in favor of new rifts centered on the hotspot.
Unusual in an oceanic environment, Iceland produces a spectrum of volcanic products from basalt to rhyolite, with rhyolites erupted only at central volcanoes. The crustal magmatic processes responsible for this spectrum of compositions includes mantle melting, crustal melting, fractional crystallization, assimilation, and recharge. The overarching question this research project seeks to address is: do magmatic processes vary systematically as a rift evolves from its inception to its abandonment?
The 2011 Iceland Keck project is the fourth in a cycle of projects investigating a series of central volcanoes erupted from the Skagi-Snaefellsnes rift zone which was active between 15 and 7 Ma. The Hrafnfjordur central volcano is the oldest of the centers investigated in this cycle, representing the early, hotspot-centered, portion of the evolution of the rift zone. Our goal is to investigate the processes of formation and evolution of magmas in the Hrafnjordur central volcano and determine the relative importance of different magmatic processes. Our data and interpretations can then be considered in the context of results from the previous projects to evaluate systematic changes during the evolution of the rift.
Potential Student Projects
2004 Iceland Keck participant Jerrod Randall high in the 2004 Westfjords study area.
The field project will involve reconnaissance mapping, sampling, and characterization of the physical volcanology of units in the study area. All students will likely be involved in all aspects of fieldwork. Most follow-up laboratory studies will include bulk rock geochemistry (XRF and ICP-MS) and thin section analysis. Some may utilize additional techniques, as available at home institutions. A range of individual student projects will be available including:
Petrology and physical volcanology of rhyolite, and possibly intermediate, lavas at Hrafnfjordur (several projects)
Petrology of basaltic units at Hrafnfjordur (potentially several projects)
Petrology of units encountered in reconnaissance of sequence above Sudavik
Physical volcanology of pyroclastic units
Mineral chemistry of volcanic units
Structural geology of Hrafnfjordur central volcano
Dikes: petrology and structure
Field Conditions & Logistics
The project will open with a field trip through the younger volcanic regions of Iceland to provide a modern analog for the older rocks we will see in the study area. The field portion of this project will be conducted in a rugged and remote area in northwestern Iceland. We will reach this area by boat from Isafjordur. The bulk of fieldwork will involve hiking off-trail in steep rocky terrain, and most days will involve hiking several kilometers with over 300 m (1,000 feet) of elevation gain. Students should be comfortable in this kind of terrain and should be in good physical condition. Iceland has a cool wet climate, and students will need to be prepared to work in rain and wind at about 10 °C (50 °F).
Students will need to either own or borrow camping gear for the field portion of the project. A period of ten days will be spent “primitive camping” with no facilities. This can be rewarding but is also challenging, and students should realistically consider whether they are up to this challenge before applying.
Due to the expense of conducting a project in Iceland, some students may need to contribute some of their stipend (or other resources) toward their travel expenses. The itinerary for travel to Iceland and Ohio is expected to cost $1,100-$1,600 (depending on departure city) of which only the first $1,100 will be paid by the project.
Courses in mineralogy and petrology are prerequisites for this project with the caveat that one position may be allocated to a student who has had structural geology but not mineralogy and petrology. Stratigraphy and field methods are recommended but not required.
Origins of Sinuous and Braided Channels on Ascraeus Mons, Mars
Figure 1: Location map and a detailed map showing the Ascraeus Mons area and the channel studied (see Figure 2).
What: Water has clearly played an important part in the geological evolution of Mars. There are many features on Mars that were almost certainly formed by fluvial processes – for example, the channels Kasei Valles and Ares Vallis in the Chryse Planitia area of Mars are almost certainly fluvial features. On the other hand, there are many channel features that are much more difficult to interpret – and have been variously attributed to volcanic and fluvial processes (Bleacher et al., 2008; Murray et al., 2009). Clearly unraveling the details of the role of water on Mars is extremely important, especially in the context of the search of extinct or extant life on Mars. In this project we will build on recent work that we have done in determining the origin of some channels exposed in the southwest rift apron of Ascraeus Mons in the Tharsis region of Mars (Fig. 1). We plan to take advantage of the recently available datasets to map and analyze similar features on Ascraeus Mons and perhaps to expand this analysis to other areas of Mars. A clearer understanding of how these particular channel features formed might lead to the development of better criteria to distinguish how other Martian channel features formed. Ultimately this might provide us with a better understanding of the role of volcanic and fluvial processes in the geological evolution of Mars.
When: July 6-August 3
Week 1: Introduction to Mars, Introduction to Mars missions and available datasets, Introduction to GIS, Project background, development of individual projects. Project database development – downloading and assembling the necessary datasets. Most of this will be done at F&M in the GIS computer lab. We plan to spend one day at GSFC where we will hear from NASA researchers about Mars research and tour the labs.
Week 2: Mapping and analysis of the channel features.
Week 3: Interpretation and expansion of the research. Field trip to Hawaii (details to be determined).
Week 4: Completion of Part 1 of the research. Development of the academic year follow-on projects. Data collection, formulation of goals. We anticipate that the students will be able to present the results of their summer work to interested scientists at GSFC towards the end of this week.
Where: Franklin & Marshall College, Lancaster Pa; NASA Goddard Space Flight Center, Greenbelt Md (day trips); Hawai’i (5 day trip).
Who: 4 students and Andrew de Wet (F&M), Jake Bleacher (NASA-GSFC), Brent Garry (Smithsonian)
Project Overview and Goals
Figure 2. The Ascraeus channel (red line) and associated rootless vents (yellow dots). White boxes outline examples from the proximal (P07_003897_1855), medial (P18_008169_1857), and distal (V13721014) sections. 250 m contours also show the emergence of a topographic ridge in the distal section.
The observations of sinuous channels on the Moon and Mars has led to debates over their formation either as a result of fluvial or volcanic processes. Apollo samples showed that fluvial processes did not form channels on the Moon (Heiken et al., 1991). However, the acquisition of new Martian data has heightened the debate over the origin of some sinuous channels. This debate demonstrates the similar characteristics of fluvial and volcanic channels and their products (Leverington, 2004). Recently we presented evidence that suggests that at least one channel system on Ascraeus Mons, previously interpreted to have formed by fluvial processes (Murray et al., 2010), was likely formed by flowing lava (Bleacher et al., 2010) (Fig. 2). In this study we compared the morphology of this braided and sinuous channel on the south-west rift apron of Ascraeus Mons to similar features on the 1859 Mauna Loa lava flow, Hawai’i and features within Mare Imbrium on the Moon. We showed that while the proximal and medial parts of this channel showed features that are analogous to fluvial channels, these parts also share similarities with volcanic features. Our analysis showed that the distal section of the channel was clearly volcanic, which strongly suggested that the entire feature was volcanic in origin. The Keck project will expand on this study by examining other channels on Ascraeus and perhaps in other locations on Mars.
Background and previous work
The development of the Tharsis Montes includes main flank formation followed by rift zone activity (Crumpler & Aubele, 1978) but the relationship between the two is not entirely clear. It is suggested that these two episodes represent a magmatic continuum (Wilson et al., 2001), two temporally unique but spatially overlapping magmatic events (Bleacher et al., 2008), and a magmatic event (main flanks) followed by hydrothermal and fluvial activity (rift aprons) (Murray et al., 2009).
In order to try to understand whether volcanic and/or fluvial processes contributed to the evolution of Tharsis Montes, our recent study focused on a channel exposed on the east side of the southwest apron of Ascreaus Mons (Fig. 1). Earlier studies done by us (Bleacher et al., 2008; Trumble et al., 2008) and by other researchers (Murray et al., 2009; Mouginis-Mark and Christensen, 2005) had suggested that the channel resulted from fluvial erosion. These studies were hampered by the limited data available at the time which meant that only part of the feature (its proximal region) could be studied. Sufficient data is now available, enabling comprehensive studies of these features in their entirety. We used a combination of MOLA (gridded data product), THEMIS, HRSC, and CTX data to examine the channel. The study also included field work on the 1859 Mauna Loa lava flow, Hawai’i, using a Trimble R8 Differential GPS with vertical and horizontal accuracies of 2-4 and 1-2 cm respectively. We compared this feature with Apollo metric images of Mare Imbrium. The lunar and terrestrial comparisons were used to provide insights into the formation of the Martian channel. The results of this study were presented at LPSC in March, 2010 (Bleacher et al., 2010). Additionally, Bleacher and Garry recently returned from Hawai’i where another analog, the 1974 Southwest Kilauea rift flow, was also studied, providing new field insights into the potential development of this feature.
The proximal section extends ~60 km from the fissure and displays anabranching, braided and hanging channels, terraced channel walls, no levees, “streamlined” islands, and flow margins that are difficult to detect or are embayed by younger materials. The medial section extends from 60-170 km. Here the channel is composed of one sinuous trench that also lacks clear levees. Generally this section of channel is surrounded by a smooth surface but sometimes shows minor leveed channels leading away from the main channel, probably due to overflow. Flow margins are difficult to determine and are sometimes embayed by younger materials. The distal section extends from 170 to >270 km and displays a significantly different morphology. At 170 km the slope decreases from 0.7-1º towards the fissure to 0.3-0.6º. Here, the channel is located along the axis of a ridge that exceeds 40 m in height. In some locations the channel is roofed over. Furthermore, rootless vents are located along the axis of the ridge. These rootless vents display topographic “caps” up to 1 km in diameter and radiating flows, some extending for several kilometers.
Results of previous work
Visual inspection of the Ascraeus channel’s proximal section shows braided and hanging channels, terraced walls, and streamlined islands all of which have led many to suggest an origin involving fluvial activity based solely upon morphologic inferences. However, new image data have enabled a complete view of the channel, including its distal portions, which display a topographic ridge, well defined flow margins, roofed channel sections, and rootless vents. We suggested that these features are indicative of a volcanic origin for the distal portion of this channel.
The conclusion that the distal portion of this channel is of volcanic origin lead Bleacher et al., (2010) to question the origin of the entire feature. All three sections of the channel show smooth transitions that suggest they are part of one continuous feature. The proximal section displays characteristics suggestive of fluvial activity. As such it is possible that this channel has experienced a mixed fluvial-volcanic history or that proximal volcanic features were mistaken as fluvial. Faced with these two scenarios we examined features of known volcanic origin on the Moon and the Earth for similarities with the Ascraeus proximal section. We observed branching and hanging channels, islands, and terraced channel walls in known volcanic terrains. Together, our observations indicated that the distal section displayed volcanic features and that the proximal section displayed features that could also form in volcanic settings. Additionally we saw no evidence for younger modification of this feature by fluvial processes. Therefore we concluded that this feature was formed by volcanic processes only, followed by partial embayment of its margins by younger materials. This interpreted origin agrees with that for a similar lava channel described on the SW rift apron which also has a rille-like proximal section (Garry et al., 2007).
Although we concluded that the origin of this feature involved volcanic processes, this inference does not preclude the possibility of fluvial activity in this region. It does, however, emphasize the importance of detailed studies of the full extent of individual features and mapping campaigns based on new Martian data.
The primary goal of the Keck project is to extend the study we recently completed to the whole of the southwest rift apron of Ascraeus Mons. We want to know if there are other channels that display similar features to the one we studied and whether these channels can be ascribed to volcanic or fluvial processes. We hope to be able to develop criteria that can be applied to Martian channel features in order to distinguish their mode of formation. Although we have concluded that one specific feature that was previously attributed to fluvial activity, is actually volcanic, it is important that we do not overextend this inference to suggest that all features in the area might share a similar history without conducting the mapping necessary to make such a statement.
Our previous research establishes a baseline from which one or two small student teams can conduct comparable studies of morphologically similar features. Such an approach will establish a data set from which sinuous, anabranching and braided channels can be compared to determine if similar or unique processes have formed this population of features. Determining the presence and role of water in the developmental sequence of the Martian surface is of utmost importance to NASA and the planetary science community.
Figure 3. Close-up view of lava on Hawai’i.
What are the characteristics and distribution of channels on Ascraeus? What are the characteristics of the proximal, medial and distal parts of these channels?
What are the similarities and differences between the channels – do all the channels have the same basic morphology? What are the differences? Is there a relationship between the morphology and age of the features?
What is the origin of the channels – volcanic or fluvial or some combination of both, or another completely different mechanism?
How do these channels compare to channels on similar volcanoes in the Tharsis area? What about other areas of Mars?
How do these channels compare to Martian channels that are clearly fluvial in origin?
Can we develop better criteria to distinguish volcanic from fluvial channels on Mars?
What do these channels tell us about the geological evolution of Ascraeus? The Tharsis Montes area? Mars generally?
Did all of these style of features form at one specific period of time in Martian history, or are they stratigraphically and temporally contemporaneous with other eruptions and channel forming events on Ascraeus Mons?
The student projects will comprise two components: Part 1 will be the summer research component, and Part 2, the following academic year component. Part 1, the summer component will focus on Ascraeus Mons. Each student will be assigned a separate area on the southern flank of Ascraeus. This is the area we know well and it will form the basis on which to expand our research efforts. This component will have the following goals and structure:
Download, georeference and assemble the required datasets. We will be using a wide variety of datasets including MOLA (gridded data product), THEMIS, HRSC, and CTX data. We will use ArcGIS to build the required databases and compete the mapping and analysis.
Recognize and develop criteria, and map the various morphological features associated with the channels.
Measure various parameters such as aerial extent, cross-sections and channel gradients.
Describe and interpret these morphological features based on our understanding of geological processes on Mars.
Compare these features to analog features on the earth (including observations made during the 5 day trip to Hawaii) and perhaps the moon.
Interpret the origin of these features. Develop criteria to distinguish fluvial and volcanic features.
Place the formation of these features into the broader context of the geological evolution of Mars by mapping their boundaries to determine their relationship with other volcanic (and fluvial) deposits.
Develop the academic year part of the project.
Part 2, the follow-up academic year component of the project may take one of many forms:
Complete a similar study in another location in the Ascraeus area – for example the northern apron appears to have similar channels.
Study similar features on one of the other Martian volcanoes – for example, on one of the other Tharsis Montes volcanoes, or Olympus Mons, or Elysium etc.
Contrast these channels with Martian channels that are almost certainly formed by flowing water – for example Kasei Valles or Shalbatana Vallis. Examine the similarities and differences between these channel features.
Do an analog study on the moon or the earth (perhaps expanding on the observations made during the trip to Hawaii).
Broader goals include – exposure to planetary geology, a greater appreciation of the role of NASA in planetary exploration and research, develop experience in doing original research, work together in a team of researchers with a common goal, exposure to research with a broad appeal and relevance.
One of the challenges of doing research on Mars is that everything is based on remote sensing, theoretical considerations, and analog studies. We will take a 5 day trip to Hawai’i to directly observe and measure processes and features that are probably direct analogs to features the students will be mapping on Mars (Figure 3). Jake Bleacher and Brent Garry have done extensive work on several lava flows including the 1859 Mauna Loa lava flow and the 1974 Southwest Kilauea rift flow. These studies have provided new field insights into the processes that may have formed the Ascraeus channel system. Prior to the project next summer, and perhaps in response to observations during the first weeks of the project, we will determine the detailed goals and focus of the field work in Hawai’i.
We might visit the Air and Space Museum in Washington which has an excellent planetary exhibition.
In addition to the Keck Symposium, we will explore the possibility of presenting the results of this research at LPSC in Houston in March 2012.
Recommended Courses (at least two)
Figure 4. Hawai’i field conditions
Most of the project will be indoors at F&M and GSFC however for the Hawai’i field trip participants need to be able to walk long distances over difficult terrain (lava flows – Figure 4). Students need to bring normal field gear including back packs, sturdy boots, water bottles, rain gear, flashlights etc (details to follow). Accommodation at F&M will be in College housing. Accommodation on Hawai’i has not been finalized and may include camping (details to follow).
Bleacher et al. (2008) JGRE doi:10.1029/2006JE002873.