Abstracts, Rocky Mountain Earthscope Workshop I
Catalyzing New Collaborations
and Advancing Fundamental Understanding of Past and Present Geological
and Geophysical Processes in the Rocky Mountain Region
Colorado Seismicity, Data Visualization and IT research at UNAVCO
Gregory Bensen (University of Colorado/UNAVCO)
Charles Meertens (UNAVCO)
Anne Sheehan (University of Colorado)
Some recent work at UNAVCO/U. of Colorado has been focused on Rocky Mountain seismicity, data visualization, and various Information Technology projects. Although the level of seismicity in Colorado has been characterized as low to moderate, little recent work has been done to accurately quantify the seismicity and seismic hazard of this region. The Rocky Mountain Front PASSCAL seismic experiment recorded many local events that previously had not been examined. We have begun to locate these events and are working to create focal mechanisms, a seismic hazard map, and calculations of stress drop for this region. At UNAVCO, we are participating in the geodynamics work in the Rocky Mountain Testbed of the GEON NSF Information Technology Research project. As part of this work, a variety of seismic tomography models, GPS velocity vector data, strain rate models and other data have been incorporated into the Integrated Data Viewer (IDV). The IDV is a visualization and analysis tool made by UCAR that has several exciting capabilities such as online collaboration, and a variety of 1-d, 2-d and 3-d viewing options. As part of the GEON effort, these collected data sets are being served on a platform-independent distributed data service. This self-describing data is easily accessible and fosters sharing in the earth sciences. Testing such systems now allows us to be more prepared for the volumes of data anticipated from various Earthscope projects.
The Socorro Magma Body as Archetype and Test Bed for Seismic Detection of Lithopheric Fluids
The Socorro Magma Body was first detected by unusually large reflected S waves from microearthquake sources by A. Sanford and students at New Mexico Tech. It was subsequently imaged, in part, by COCORP deep reflection profiling, and most recently by analysis of receiver functions using teleseismic sources. Active inflation of the body is indicated both from historical leveling surveys and INSAR. The interpretation of these geophysical anomalies as due to midcrustal magma has greatly influenced the interpretation of similar anomalies in other parts of the world. That this feature has been detected by a diverse set of seismological and geodetic techniques has demonstrated their viability as tools for identifying other fluid bodies in the lithosphere. However, key questions remain concerning both the nature of the Socorro body and the technical limits of the techniques used to map it. That the Socorro body is fluid is beyond serious question; whether that fluid is magma or geothermal brine remains open. The full extent of the body, whether it is "frozen" in part, and its relationship with smaller bodies less directly inferred remain to be determined. The resolution and detectability limits of the relevant geophysical techniques remain to be quantified (why no MT anomaly?; how thin can it be and still be discernible?; how close must a station be to pick up its effect on teleseismic arrivals?; can surface seismics detect changes in the thickness/geometry of the body over time?). For these and other reasons, the SMB deserves special attention in any EARTHSCOPE program for the southern Rockies, both in its own right and as the avatar for investigation of similar anomalies elsewhere in the world.
Questions Regarding Crust-Mantle Evolution
Below are some questions that I feel could be addressed at the Earthscope Workshop: 1) Has a significant volume of juvenile crust been underplated beneath the CP-RM (Colorado Plateau – Rocky Mtn) region since the Proterozoic? 2) Where is the restite for the large volumes of felsic igneous rock formed during both the Paleoprotereozoic and the Tertiary? Can this be recognized from geophysical results? 3) Is it possible to map the location of the buoyantly subducted Farallon plate using the "flare up" of magmas after the plate detached and sank into the mantle? 4) What do subhorizontal reflectors and other geophysical anomalies mean in the crust and lithospheric mantle? Uplifted crustal sections show the deep crust is highly deformed and folded, but we don't see this in the geophysics. 5) Can we see the bottoms of plutons in the seismic data and if so what do they look like and how do they constrain pluton origin? 6) Using Poissons ratio, is it possible to map the silica content of the crust in the CP-RM region? If so, what do the results tell us about crustal origin? 7) Is the seismic anisotropy similar in the crust and lithospheric mantle, and if not, what does this mean in terms of the origin and evolution of the crust-mantle system?
Travertines, Springs and Gases of the Southwestern US: Xenowhiffs Linking Tectonism and Water Quality
A genetic model for the formation of travertine has emerged from study of the deeply-dissected hydrologic system of Grand Canyon of the southwestern U.S. The active Rio Grande rift system also hosts extensive travertine deposits. Water and gas chemistry of active travertine-depositing springs reveal clues to the genesis of vast quantities of Quaternary travertine. Travertine formation is a three-stage process: acquisition of solute by a groundwater, transport of dissolved constituents, and deposition of travertine. The role of CO2 degassing in the depositional phase of travertine formation is widely recognized. The amount of calcite dissolved from limestone aquifers (the calcite load of the ground waters) in the transport phase of the process depends critically on the amount of CO2 input. The higher the amount of CO2, the more calcite can be dissolved. Hence, the amount of travertine in the depositional portion of the system is a physical record of the CO2 entering the system over time in the acquisition phase. Extensive travertine accumulations are thus an expression of high fluxes of CO2. Travertines and travertine-depositing springs are preferentially located along basement-penetrating faults. Our model for solute acquisition focuses on the role of magmatism in active extensional tectonic settings as a source of excess CO2. Spring waters associated with active travertine accumulations (lower world waters) are warmer, more saline (Na-Cl and Na-HCO3), richer in CO2, and elevated in 87/86-Sr relative to spring waters derived from Colorado Plateau aquifers (upper world waters). Gas analyses from lower world waters record low Ar/He and N2/He, and 3/4-He ratios up to 0.15 Ra, suggesting contributions of mantle-derived He, and its carrier gas CO2, from nearby volcanic fields. 87/86-Sr in springs ranging from 0.710 to 0.735, as well as mixing relationships among other geochemical parameters, suggest complex mingling of upper and lower world waters within the aquifers. The radiogenic strontium isotope signal of lower world springs, contributed by waters that are deeply circulated through Precambrian basement, may account for the previously observed downstream increases in Colorado River 87/86-Sr. Similarly, natural inputs from deeply sourced saline spring waters affect the Colorado River salinity as it crosses the western Colorado Plateau and enters the Basin and Range province; and the Rio Grande as it travels southward.
Adding “Time” to the Earthscope Image: Petrologic Analysis, Structural Analysis, and Monazite Geochronology of the Proterozoic Crust
The EarthScope (US-Array) image of the southwestern Lurentian crust will be a composite image, superimposing tectonic events, including: (1) early arc development (ca. 1.78-1.72 Ga); (2) accretion of arcs, crustal shortening, and tectonic burial during the Yavapai and Mazatzal orogenies (1.7-1.65 Ga); (3) crustal shortening, metamorphism, and widespread plutonism (1.45-1.35 Ga); and (4) localized thermal, deformational, and plutonic events during the Grenville orogeny (ca 1.3-1.0 Ga). After exhumation, the crust was further modified by largely brittle events in the Neoproterozoic and Phanerozoic. In many parts of the orogen, older structures have localized younger deformations, younger events have reactivated older fabrics, and similar structures or assemblages have been produced during very different tectonic events. Microprobe monazite geochronology combined with microstructural and petrologic analysis have proven to be extremely valuable for timing deformation and metamorphic events and thus, for deconvoluting multiphase tectonic histories. In Arizona, rocks are dominated by 1.65-1.7 structures and fabrics with little 1.4 Ga overprint. In Colorado, older high-T, 1.65-1.7 Ga gneissic fabrics have been distinguished from localized 1.4 and post-1.4 Ga shear zone fabrics with distinct styles and kinematics. In New Mexico, 1.4 Ga deformation and metamorphism are intense, but in situ geochronology has illuminated a gradient in the 1.4 Ga event, has identified some cryptic 1.65 Ga fabrics, and has delineated several 1.4 Ga shear and fault zones. The combination of surficial P-T-t-D analyses and Earthscope imaging will provide a better picture of the tectonic history of Laurentia and the significance of structures involved with its evolution.
Origin of Phanerozoic Continental Interior Magmatism in Colorado
Lang Farmer (University of Colorado-Boulder)
Phanerozoic magmatism in Colorado, as in other interior portions of western North America, has long defied conventional notions of how continental magmatism is generated. Particularly enigmatic are the magmatic events that occurred during the Laramide orogeny (~60-80 Ma) and the mid-Tertiary (~25-30 Ma). Laramide igneous rock in Colorado are largely mafic to intermediate in composition, restricted geographically to the Colorado Mineral Belt, and, based on limited radiogenic isotope data, evidently derived from melting of mafic composition lower continental crust. Mid-Tertiary igneous rock, in contrast, are dominated by large volume silicic ash flow sheets found from the present-day Front Range in the north to the San Juan volcanic field to the south that were likely derived from contemporaneous, mantle derived magmas. Both magmatic episodes occurred during subduction of oceanic lithosphere at the western edge of the continent, but at positions up to ~1,000 km from the plate margin. Past workers have attributed the older magmatic event to a period of low angle subduction, with mid-Tertiary magmatism being attributed to resteepening of the slab. What is unclear, however, is exactly how any such changes in the disposition of the subducted oceanic lithosphere triggered continental interior magmatism. To fully address this issue, the sources of parental magmas (crust, mantle lithosphere, subcontinental mantle, etc.) as a function of space and time in Colorado must be well defined. Unfortunately, most existing age determinations from Colorado igneous rocks are low precision K-Ar determinations and may not accurately depict temporal patterns in Colorado magmatism. Furthermore, due to the paucity of preserved Laramide volcanic rocks, the full range of primary magmas generated, and the importance of mantle-derived magmatism, during this igneous event are not known. Nevertheless, a better understanding of the sources and volumes of magmatism produced during the Phanerozoic in Colorado is critical not only to the general understanding of the behaviour of deep portions of continental interiors, but also to assess the present day physical state of the mantle beneath Colorado. Because the latter information will be one of the main products of USArray activities in the Rocky Mountains, it seems timely to now renew geochronologic and geochemical studies of Colorado igneous rocks.
Helping Facilitate the Sharing of Discoveries through the National Park Service
Judy Geniac (Geologic Resources Division, National Park Service)
As the NPS Servicewide geoscience research facilitator and the geoscience partnership manager, I am working with both the lead and on-the-ground EarthScope researchers. With them, I am facilitating the placement of monitoring equipment throughout a number of units in the National Park Service. In attending the workshop and working with others, I can facilitate efforts to help park managers and staff understand the importance of this NSF project: expanding our knowledge through science, expanding the public understanding of our continent; and helping gain a perspective of the relative importance of this information to the management of the parks themselves. In the past workshop that I attended, I got a much better understanding of what Earth Scope is about. I believe that this workshop will help me better convey that understanding and therefore help me facilitate the research and interpretation of this incredible NSF endeavor. The NPS is just beginning the process to help disseminate information to potentially millions of NPS visitors. These visitors will witness for themselves the incredible geologic heritage we have, but it is just as important to help them watch science in progress and in help them gain their own understanding of the dynamics that shaped and continues to shape our parks. I will work closely with Karl Karlstrom, Linda Lutz-Ryan, Phil Zichterman, Laura Crossey, as well as park managers, park staff, and researches across the country. This regional workshop will be key to helping parks in the area, as well as parks outside the region.
Crustal low-velocity zones and volcanism in the Rocky Mountains and Colorado Plateau
Hersh Gilbert and Matthew
Fouch (Arizona State University)
Anne Sheehan (University of Colorado-Boulder)
Integrating results from several past seismic studies within the Rocky Mountains across Wyoming, Colorado, and New Mexico provides insight into large-scale crustal structure at previously unattainable levels and exhibits heterogeneous crustal and upper mantle structure. Receiver function imaging using much of the available broadband data from the Rocky Mountains and Colorado Plateau displays variations in crustal thickness from less than 40 km in central Utah to over 50 km in northwestern Colorado. The crust appears to gradually thin to the west from the Rocky Mountains into the Colorado Plateau indicating that an abrupt crustal transition does not separate the two provinces. Within the Rockies, we identify a low-velocity zone at 20 km depth near the San Juan volcanic field in southwestern Colorado. Other crustal low-velocity zones are present at similar depths near the Rio-Grande rift. In the Colorado Plateau we deployed a coarsely spaced array of broadband seismometers in Arizona to study crustal and upper mantle structures between the southern Colorado Plateau into the Basin and Range. We observe low velocity zones at depths of ~15 and 60 km below the southern Colorado Plateau. The deeper of these two features may help explain the dynamics of plateau uplift, while the shallower low-velocity zone likely relates to recent volcanism. Relations between low-velocity zones identified by receiver functions and details of properties such as percent partial melt are still being determined. Identifying such low-velocity zones and determining their link to volcanic events provides constraints for analyzing the likelihood of future volcanism and its associated hazards.
Geological features in the southern Great Plains: Important targets to the Rocky Mountain EarthScope group
Harold Gurrola, Cal
Barnes, and Melanie
Barnes (Texas Tech)
TTU investigators are involved with an investigation of the southern granite-rhyolite province, beneath the Texas Panhandle and adjacent New Mexico. The granite-rhyolite province is the youngest part of one of the most voluminous examples of crustal melting in Earth history. The Llano front in central Texas is the southern portion of the Grenville orogeny, but the precise location of the Llano front and continental suture is poorly understood. The Southern Oklahoma Aulacogen (SOA) was deformed during the Ouachita and Ancestral Rockies orogenies to form mountains far inboard of Ouachita or Ancestral Rockies orogenies. Seismic investigations of the upper mantle beneath the Great Plains indicate that the remnant of the Farallon Slab is present in the transition zone beneath the Texas Panhandle. Considering the importance of the passing of the Farrallon slab in the development of the Basin and Range province, the Rio Grande Rift and Rocky mountains, an investigation of the current state of the Farallon slab will be important in an understanding the development of this region. To understand the relationship between these features and the transition from the Rockies to the Great Plains an extensions of La Ristra and CDROM must cross these features which will inevitably require the seismic profiles to pass near TTU. Not only can we help with seismic investigations but petrologic work by TTU investigators on well cuttings of basement rock in the region will be an absolute necessity to interpret seismic data collected in this region.
Thermal processes and EarthScope
Robert Harris (University of Utah)
The EarthScope project is designed to elucidate the dynamics and evolution of the North American continent. To reach that goal, focused studies of the continental seismic structure, the strength of the lithosphere and modes of deformation, the patterns of stresses and strain and the manner in which the lithosphere responds to excitation during earthquakes are all a high priority. The common factor linking these EarthScope objectives is the thermal state of the lithosphere. Although not an explicit component of EarthScope an understanding of the thermal structure and associated thermal processes plays a key role in interpreting the observations generated by EarthScope infrastructure. Recommendations and conclusions reached during a workshop held to highlight thermal processes within the context of EarthScope will be discussed with special attention given to the Rocky Mountain region. These conclusions include: 1) The recognition that an important component to achieving EarthScope goals will be the ability to separate the influences of temperature, composition, and fluid content in the crust and upper mantle. Discerning these influences is an important component to interpreting upper mantle dynamics from seismic anomalies and rheology from geodetic measurements. 2) The need to understand better and define the spatial characteristics of thermal transition zones. 3) The need to improve understanding of heat production within the crust, both as a function of depth and laterally is needed to improve estimates of the lithospheric temperature field.
Testing Models of Laramide Arch Uplift in the Bighorn Mountains, Wyoming
Dennis Harry (Colorado State University)
Current kinematic hypotheses for Laramide deformation in the Rocky Mountains are amazingly diverse, including models invoking thrusting of segmented lithospheric blocks, ductile thickening of lower crust, and buckle folding at both lithospheric and crustal scales. Proposed connections to plate margin processes include subcrustal shearing during low-angle subduction and end-loading of the lithosphere driving continental buckling and detachment. Moho geometries predicted by the above hypotheses differ radically, with detachment models predicting a planar Moho under the arches, lithospheric buckling models predicting an upwardly deflected Moho, and crustal thickening models predicting a downwardly flexed Moho below a crustal root. We are beginning a project to test these models of Laramide arch uplift by developing a 3D image of the Bighorn arch from geologic surface and industry subsurface studies of upper crust geometry combined with gravity and passive seismic data constraining deeper crustal geometries. 4D (3D plus time), volume-balanced restoration of the Bighorn arch combined with geodynamic models integrating flexural, buckling and lower crustal flow processes will test and refine existing tectonic models for basement-involved arches.
Seismic tomography using data from large seismic networks in China with inferences for Earthscope
Tom Hearn (New Mexico State University)
Both Pn and teleseismic tomography have been accomplished using over 100 stations from the Chinese National network. This network covers a large 40x30 square degree region - a size similar to that of Earthscope. While the coverage presents exceptional opportunities, there are also several difficulties that it creates. The lack of coverage for regional phases in relatively aseismic regions, the tomographic limits on resolving crust and upper mantle structure due to sparse station coverage, and the need to collect a large, but coherent travel-time data set. This poster shows how we have dealt with these issues using the Chinese data and how our experience relates to Earthscope.
Results of a Receiver Function Study on the 410 and 660 km Discontinuity Structure Beneath the Laramie Array
The Laramie array consisted of a dense (2-km station spacing) deployment of 30 broad-band seismometers along a NW oriented line for 10 months from 2000-2001. The array recorded a high-fold dataset of teleseismic P-wave arrivals and coda. The distribution of seismicity provides three well sampled back-azimuths with the NW and SE back-azimuths displaying excellent source moveout lines with sources distributed between 30-100. These two moveout lines allow for excellent resolution of the moveout of candidate PdS arrivals. Previous work in the similarly dense Billings array (Dueker and Fee, in review) observed large tangential arrivals from the 410 and 660 km discontinuities, therefore both radial and tangential PdS signals will be analyzed in the Laramie array. Evidence for a persistent lateral negative velocity gradient on top of the 410 discontinuity will be evaluated, consistent with the transition zone ?water-filter? model (Bercovici and Karato, 2003). Previous work on the transition zone beneath the Billings array (Dueker and Fee, in review) suggests the negative velocity gradient is present just to the north of Yellowstone Park. Work on the crustal structure beneath the Laramie array (Dueker and Yuan, in review) shows a complex crustal structure. Band pass filtering in the 0.1-1.0 Hz range of stacked receiver functions will help to enhance transition zone PdS conversions from high frequency crustal scattering. The final proxy for recognition of the negative velocity gradient atop the 410 discontinuity is to demonstrate that the signal displays correct moveout.
The Dynamic Nature of the Continental Crust-Mantle Boundary: Crustal Evolution in the Southern Rocky Mountain Region as an Example
Randy Keller (University of Texas-El Paso)
Karl Karlstrom (University of New Mexico)
Michael L. Williams (University of Massachusetts-Amherst)
Kate Miller (University of Texas-El Paso)
Christopher Andronicos (University of Texas-El Paso)
Alan Levander (Rice University)
Cathy Snelson (University of Nevada-Las Vegas)
The evolution of continents involves modification of the lithosphere through time, including changes in crustal thickness and composition that create a dynamic crust-mantle boundary (Moho). The geological history of the Southern Rocky Mountain region is relatively well understood and recent additions of modern seismic data provide an ideal opportunity to investigate the evolution of the crust. The results presented in this volume show that crust in the Southern Rocky Mountains is relatively thick compared to the global average for the continents. The mafic lower crust and crust-mantle boundary of the Proterozoic provinces of the southwestern U.S. likely formed, and reformed, in several stages. Initial formation of juvenile continental crust took place by development and assembly of magmatic arcs between 1.8 and 1.6 Ga. Volcanic and plutonic rocks of this age record whole-crust differentiation and probably resulted in a mafic lower crustal residue. From 1.45 to 1.35 Ga, the crust underwent another period of differentiation leading to emplacement of A-type granites in the middle crust across southern Laurentia. Petrology of magmas, widespread metamorphism, and voluminous granitoid emplacement ca. 1.4 Ga are best explained by mafic underplating. Subsequent mafic additions to the lower crust likely took place at each of the times when basalts were emplaced in the Rocky Mountain region (1.1 Ga Grenville orogeny, Laramide orogeny, Oligocene ignimbrite flare-up and Neogene extensional tectonism), but these events were more local in distribution and not widespread enough to produce the thick, mafic crust observed over an extensive area.
Laramide and Post-Laramide Cooling History of the Southern Rocky Mountains, Southern High Plains, and Rio Grande Rift
The base of an apatite fission-track (AFT) partial annealing zone (PAZ), which corresponds to a fossil ~110°C isotherm, formed across much of the southwestern and mid-continental United States during a period of relative tectonic quiescence in late Cretaceous time. This paleoisotherm was subsequently faulted and folded during Laramide and post-Laramide deformation, thus providing a valuable structural datum. The base of a fossil PAZ in the Front Range of Colorado, which separates AFT cooling ages of 45 to 70 Ma at low elevations from AFT ages >100 Ma at higher elevations, has proved useful in evaluating the nature of Laramide deformation. Furthermore, the thermal effects of changes in thickness in the late Cretaceous Pierre Shale along strike in the Front Range and of pluton emplacement along the Colorado Mineral belt have been constrained using AFT data. The High Plains between New Mexico and Oklahoma remained relatively stable until ~30 Ma; here, the base of the PAZ separates AFT ages of >100 Ma at shallow depths from ages of 11 to 30 Ma at greater depths. The cooling history of the southern High Plains reflects the complex interaction of the thermal blanketing effects of Cretaceous shales, flexural uplift and erosion related to the Rio Grande rift, and regional scale exhumation driven by elevated heat flow and mantle density modification associated with extensive middle-Tertiary volcanism. Additional low temperature thermochronology data from transects that extend from the rift to the plains will be key in teasing out the relative importance of these mechanisms.
Effects of Cenozoic Magmatism and Tectonics on Evolution of Continental Lithosphere, N. Rocky Mountains, USA
An important geologic problem concerns the formation and longevity of continental lithosphere. Understanding the architecture of ancient cratonic lithosphere is hampered by subsequent geologic processes that may modify its structure and compositional makeup. Conversely, it is important to understand how the lithosphere influences and is influenced by younger tectonic and magmatic processes. An interdisciplinary investigation centered on southern Idaho is proposed as a focal area to address such questions. The lithosphere in this area comprises a collage of terranes formed in Archean to Proterozoic times. The character and distribution of these domains have been inferred from studies of limited surficial exposures, and isotopic geochemistry and petrology of younger superposed igneous rocks (and entrained xenoliths). Yet the exact history of lithospheric terranes, the nature and loci of their boundaries, and the role they play in subsequent magmatism are largely unresolved questions. For example, how has lithospheric mantle been affected by Phanerozoic subduction and mass transfer of fluids and magmas? If such processes modify old mantle domains, how is this reconciled with preservation of provincial differences in isotopic compositions of Cenozoic volcanic rocks? How has the lithosphere responded to tectonic processes such as development of Basin and Range extension? In particular, how has lithospheric thickness varied spatially and temporally with respect to its role as a chemical, thermal, or mechanical boundary layer? What role does the lithosphere play in controlling loci and compositions of younger magmatic provinces? These and related questions can be addressed with new resolution by the EarthScope initiative.
Paleo-subduction and Modern Basalt Extraction Structures in the Southern Rocky Mountains: Multi-band Images from the CD-ROM Experiment
Alan Levander and CD-ROM Working Group (Rice University)
The CD-ROM seismic projects targeted two Paleoproterozoic suture zones in the western U.S. in a north-south study corridor that extends from central New Mexico to central Wyoming. Seismic reflection, refraction, and teleseismic measurements were made across the Cheyenne Belt in southern Wyoming, and across the Jemez Lineament in northern New Mexico. The Cheyenne Belt is a profound geologic boundary separating the Archean Wyoming craton from island arcs accreted to the proto-continent in the Paleoproterozoic. The Jemez Lineament is a linear trend of modern volcanics extending SW from southern Colorado to Arizona, and also marks the southern edge of the suture between Yavapai and Mazatzal Paleoproterozoic island arc terranes. Karlstrom and Humphreys (1998) have speculated that the ancient accretion boundaries influence Cenozoic tectonism in the western U.S., noting the correlation of NE-SW low velocity upper mantle tomography anomalies with geochemical boundaries and mapped suture zones in the Southern Rocky Mountains. At the Cheyenne Belt, the combined reflection-refraction-teleseismic datasets show crust and upper mantle subduction structures inferred to date to continental accretion and stabilization of the southwestern U.S. Of particular note are a north dipping high velocity slab structure and a fragment of subducted crust imaged in both the P and S tomography and prestack depth migrated receiver function images (Yuan and Dueker, 2004; Zurek and Dueker, 2004; Levander and Niu, 2004). At the Jemez Lineament the reflection data image a bivergenet orogen marking the Yavapai-Mazatzal suture in the crust (Magnani et al., 2004). Refraction velocities in the upper mantle under the suture zone suggest that the upper mantle contains 1% partial melt (Levander et al., 2004). In the same upper mantle region P and S tomography show low velocities that correspond to a series of moderately bright but complicated upper mantle events in the pre-stack depth migrated receiver function images (Yuan and Dueker, 2004; Zurek and Dueker, 2004). We have modeled this complex series of events in the upper mantle as the source zone of the recently erupted basaltic magmas found along the Jemez Lineament portion of the CD-ROM profile. We speculate that the paleo-suture zone acted as a conduit for the basaltic magmas to pass through the crust.
Towards a GPS Geodetic Investigation of Rio Grande Rift Deformation
Anthony Lowry (University of Colorado-Boulder)
The Rio Grande rift is perhaps the most important actively deforming province in the western United States to be left off the list of Plate Boundary Observatory focus deployments. Geological data and existing continuous CORS network GPS sites suggest extension of about 1 mm/yr with tantalizing evidence for an additional few mm/yr of left-lateral strike slip. However, uncertainties in these data are large and, while the PBO backbone sites will improve the picture, the combined existing and proposed sites are far too sparsely distributed to address questions regarding the dynamics and mechanisms of extension. We suggest that a focused deployment of quasi-continuous, quasi-campaign GPS sites could address some of these questions in a cost-effective manner. This presentation will review what we already know about the rift, including the range of hypothetical mechanisms for rifting, and assess what kinds of geodetic information will be needed to achieve a better understanding. It will also discuss monumentation and occupation strategies for minimizing cost, as well as the technical and other advances that must be made in order to achieve high accuracy estimates of GPS velocity in low-strain-rate locales such as the Rio Grande rift.
National Park Service and EarthScope Education and Outreach
Linda Lutz-Ryan, Phil Zitcherman, and Judy Geniac (National Park Service)
Karl
Karlstrom and Laura Crossey (University of New Mexico)
Attending this workshop will hopefully strengthen and build the NPS and ES partnership. The National Park Service has been partnering with EarthScope (ES) for about two years. The partnership in place has assisted ES in making initial park contacts for deploying seismic equipment, facilitating contacts with other agencies, and development of education plans and media. The discoveries resulting from this project will benefit the natural resource information/interpretation data and used to further National Park Service education and resource management goals. The Geologic Resource Division of the National Park Service Washington Office requested a Long Range Interpretive Plan development workshop from the Intermountain Support Office for the National Education Group for EarthScope. The resulting document will facilitate and enhance the usefulness of EarthScope data for NPS and community purposes. Some of the goals of this partnership are being implemented. In park units that have seismic equipment already in place, they are working with ES to connect to the ES network to contribute to the seismic data collection. Some parks have been selected by the ES E&O for developing interpretive media for ES to be used in both parks visitor centers and community centers. Other parks with related geologic resources are being selected for either permanent or temporary hosting of an instrumentation array. The National Park Service would like to now begin partnering with scientists and universities to further develop media that would enhance the interpretation of the related geologic resources.
The 2003 Potrillo Volcanic Field Seismic Experiment, Southern Rio Grande Rift: Preliminary Results and Implications for EarthScope Science Plans for the Southern Rocky Mountains
Kate C. Miller, Matthew G. Averill, and Steven Harder (University of Texas-El Paso)
The Rio Grande Rift is a major Tertiary tectonic feature that profoundly modifies the lithospheric structure of the southern Rocky Mountains. Patterns of magmatism and extensional structures of the rift both crosscut and reoccupy older structures including those associated with Precambrian continental assembly, late Paleozoic Ancestral Rockies and late Mesozoic to Early Tertiary Laramide tectonism. Whereas, results from the recent RISTRA experiment are providing remarkable new insights into lithospheric scale processes in the rift, modern active source experiments that can illuminate the connection between mantle, crustal, and surfaces processes are lacking. An exception is the Potrillo Volcanic Field (PVF) seismic experiment conducted along the border between Mexico and New Mexico in the southern Rio Grande Rift. The experiment was designed to study crustal structure in a region centered on a Quaternary volcanic field that contains localities for xenoliths from both the crust and upper mantle. The experiment, conducted in May of 2003, was comprised of 8 shots of 2000 lbs., and 793 seismic recorders deployed at variable spacings of 100, 200, and 600 m along a 205 km-long profile. Near vertical reflection shot data image numerous intracrustal reflections, complex reflectivity at Moho near 11 s, particularly beneath the PVF, and reflected energy due to the conversion of P to S at the Moho. A preliminary velocity model shows a change in mid-crustal velocities from 5.5 – 6 km/s west of the PVF to 6 – 6.5 km/s to its east. The Moho may be as deep as 35 km and likely dips to the east. This experiment serves to anchor crustal structure in the southernmost portion of the rift and as an example of the kind of results that could be expected to the north.
Tracing the Origins of Travertine-depositing Springs of the Colorado Plateau Region, USA
Travertine-depositing springs located in the Colorado Plateau region of the southwestern U.S. are hypothesized to be genetically linked to mafic magmatism and extensional tectonics, providing a window into a previously unrecognized component of deeply circulated hydrothermal fluids influencing groundwater. Active springs are commonly located along basement-penetrating faults and with large accumulations of Quaternary travertines, implying that these hydrologic systems have persisted through time. We used aqueous constituents including SO4, Cl, Br, HCO3, δ18O, Sr, and 87/86-Sr to trace the origins of travertine-depositing spring waters. Springs in the plateau region fall on a trend between dilute and very saline end-members. Within the Rio Grande rift, our data support a simple binary mixing model. Grand Canyon region spring chemistry is more complex requiring at least three end-members. Simple evaporative concentration of meteoric waters is ruled out on the basis of Cl/Br trends, which suggest the mixing of different end-member waters. Mixing models using Cl vs. Cl/Br and Sr vs. 87/86-Sr indicate mixing of dilute, nonradiogenic shallow ground waters with far less than 1 % of saline, radiogenic, hydrothermal fluids to produce the observed spring chemistries. Analysis of dissolved gases within the spring waters also reveals a mixing trend between atmosphere/soil gas with an end-member dominated by CO2 (high CO2/N2) ; gas compositions range to over 99 volume % CO2 in some springs. Trace gas analyses shows elevated He concentrations (low N2/He) in some springs suggestive of a deep crustal or mantle origin for the gases, linking them to magmatism and extensional tectonics.
Geodetic Determination of the Eastern Terminus of the Pacific North-American Plate Boundary
Andrew Newman (Los Alamos National Laboratory)
The Pacific-North America diffuse plate boundary extends over 1000 km wide region, from the Pacific coast in the west to east of the Rocky Mountains and Rio Grande Rift. Though most of the western portion, which has had many large historic and recent earthquakes, has been well studied by many groups, the eastern terminus is poorly understood. This is because deformation across the region is slow, less than ~3 mm/yr (Savage et al., 1985), and the region is complicated by influences of the Colorado Plateau, the Rio Grande Rift, the Southern Basin and Range and locally active volcanic centers. Using a combination of campaign and continuous GPS and interferometric synthetic aperture radar (InSAR) measurements across the region, over the 10 year life of EarthScope, we would be able to resolve: 1. The eastern terminus of the Pacific-North America diffuse plate boundary zone to better than 1mm/yr. 2. Measure extension and uplift rates across the Rio Grande Rift and Southern Basin and Range and determine how strain is partitioned between them. 3. Measure and model volcanic/magmatic induced deformation likely associated with the RGR over the Socorro Magma Body and the Valles Caldera. 4. Measure uplift and rotation of the Colorado Plateau and determine its role in concentrating strain on the Rio Grande Rift and the Basin and Range. In order to fund a project such as this, it will be beneficial to build a team of researchers from local/national universities and national laboratories. Potential funding may come from a cooperation between NSF/EarthScope and the Department of Energy in the interest of assessing regional long term hazards from volcanic and seismic sources (a Defense nuclear facility safety mandate).
Downwelling Along the Western Edges of the Great Plains: Implication for Small-scale Convection
James Ni and Michael West (New Mexico State University)
Richard Aster (New Mesico Tech)
Stephen
Grand (University of Texas-Austin)
Dave Wilson (New Mexico Tech)
Wei Gao (University of Texas-Austin)
W. Scott
Baldridge (Los Alamos National Laboratory)
From LA RISTRA experiment we have learned that the Rio Grande rift is a result of symmetric streching of the lower curst and uppermost mantle. These results suggest a new picture of rift dynamics associated with uniform streching at low strain rate. The low shear wave velocity beneath the rift suggests partial melts beneath the entire rift. Strong temperature and viscosity contrast with adjacent cratons drives small-scale convection in the mantle beneath the edges of the Great Plains and Colorado Plateau. LA RISTRA imaged the downwelling of cold lithosphere beneath the eastern edge of the Great Plains and a less pronounced downwelling beneath the western edge of the Colorado Plateau. These findings constitue the most detailed evidence to date of ongoing small-scale convection beneath the southwestern U.S. What we do not yet know is whether the downwelling is limited to isolated blobs or a long sheet. A denser spaced 2-D array, with an area of 600 by 400 km and station spacing at ~40 km should be able to resolve this question.
Surface Waves and EarthScope: The Nature and Promise of Broad-band Surface-wave Measurements from the Random Wavefield
Michael H. Ritzwoller and N.M. Shapiro (Colorado University-Boulder)
M.
Campillo and L. Stehly (J. Fourier University)
We argue that a new method of analyzing broad-band seismic recordings may revolutionize studies of surface wave dispersion using EarthScope data. We demonstrate that coherent information about earth structure can be extracted from background seismic noise and that this information, within the context of EarthScope, makes the technique preferable to traditional information obtained on ballistic waves (with approximately known source and trajectory). The measurements are obtained by cross-correlating vertical component records for several days of seismic noise observed at various station-pairs separated by distances from about 100 km to more than 2000 km. Coherent broadband waveforms emerge with dispersion characteristics similar to predictions from traditional Rayleigh-wave tomography maps constructed using ballistic surface waves. Background seismic noise, therefore, contains a significant component of Rayleigh wave energy that is the basis for the measurement. This energy is probably excited by oceanic microseisms and atmospheric forcing and these signals form a wavefield in which phase is randomized by a multiplicity of sources. This random wavefield provides a new source of broad-band surface-wave information. Such measurements may be particularly useful in the context of dense arrays of broad-band seismometers, such as EarthScope/USArray/ANSS, that will produce numerous inter-station paths that are not as directly sampled by ballistic waves. We show that the measurements obtained on the random wavefield can be made reliably to shorter periods than those made on the ballistic wavefield and, therefore, promise to provide better constraints on crustal structure. In addition, the spatial sensitivity kernels for the random wavefield are narrower than those for the traditional measurements and, therefore, promise improved spatial resolution in the context of dense arrays. Finally, the measurements are relatively unaffected by source location and phase and will, therefore, be free from potential sources of bias that affect traditional tomographic methods.
EarthScope Education and Outreach and Senses of Place in the Southwest
Steven Semken (Arizona State University)
In the southwestern United States, geoscientists conduct field research in places that have prior personal and cultural meanings for indigenous American Indians, and for other groups who later settled in the same region. The term sense of place refers to meanings and attachments that people have for places. In many Southwestern cultures, experience with geological phenomena is an identifiable component of sense of place, and this may influence how learners in these cultures construct geological knowledge. Hence place-based geoscience curricula and teaching methods that acknowledge and enrich sense of place have been recommended to enhance science literacy among American Indian and other minority students, and bring more of them into the geoscience profession.
EarthScope education and outreach activities in the Southwest can contribute substantially to formal and informal place-based geoscience teaching: not only by bringing real-time experiments and web links into rural minority communities, but by disseminating detail on continental structure and evolution that will enable educators to teach about the tectonic history of any place through time, even where subdued topography, lack of exposure, or seismic and volcanic quiet may conspire against this. In turn, a richer understanding of culturally-situated local senses of place, and the land-use etiquette or regulations that may emerge from these, will assist EarthScope researchers in working more efficiently with local communities to permit instrument deployments.
Rayleigh wave tomography of the Yellowstone Hotspot and the Wyoming Craton
A high resolution fundamental mode Rayleigh wave inversion for VSV structure of the crust and uppermost mantle of the Yellowstone Hotspot shows 6.5% crustal velocities variations, with an E-W slow velocity trend not aligned with mantle low velocities. A region of high crustal velocities occurs to the NE of Yellowstone, and probably delimits a region of mafic underplating. Throughout the model, there is a relatively high velocity mantle lid, ranging in thickness from 20 km along the hotspot track, to 40 km NE of the Hotspot. Variations in lid thickness are inconsistent with a zone of preexisting lithospheric weakness along the Hotspot trend. Along the Hotspot track, a well-defined low velocity channel has a minimum velocity of 3.6+/-0.2 km at 75-85 km. This minimum velocity is 8-10% lower than found under Hawaii, Iceland, or the East Pacific Rise suggesting Yellowstone melt resides in a different topology. Outside the Hotspot track, the lowest mantle VS is 4.15 +/- 0.15 km/s, at 90 km depth. This velocity is similar to that found under 4-20 Ma oceanic lithosphere and implies that below 90 km the Wyoming mantle is sub-solidus adiabatic asthenosphere, not lithosphere.
Recurrent Intracontinental Deformation and Magmatism in the Colorado Mineral Belt: Targeting a Persistent Lithospheric Structure using Rocky Mountain EarthScope
Colin A. Shaw (University of Wisconsin-Eau Claire)
Geologic and geophysical evidence suggests that the Colorado mineral belt (CMB) follows a persistent lithospheric flaw that has been repeatedly reactivated as a shear system and magma conduit during the past 1.8 b.y. The Rocky Mountain deployment of Earthscope presents a unique opportunity to investigate the deep structure of the CMB and its relationship to other structures. The CMB is defined by a NE-trending swath of Laramide plutons, faults, and mineral deposits that are spatially associated with a system of NE-trending Proterozoic shear zones. The tectonic history of the CMB includes ~1.7 Ga ductile strain during continental assembly, ~1.4 Ga ductile shear (mylonite) and coeval seismogenic faulting (pseudotachylyte), minor Paleozoic faulting, and Laramide plutonism and mineralization. A significant change in Laramide structure occurs across the CMB suggesting that the belt delineates some sort of rheological boundary. Evidence that the CMB remains a significant lithospheric structure includes a prominent gravity low (mid-crustal?) and a region of anomalously low velocity in the shallow mantle (Aspen anomaly). The highest topography in the southern Rocky Mountains occurs at the intersection of the CMB and the Rio Grande Rift. Specific research focuses include: the Aspen anomaly, source of the CMD gravity anomaly, relationship between the CMB and Laramide structure. Earthscope will serve as a focus for integrated studies of the CMB that will elucidate processes of intracontinental tectonism and advance understanding of rheologic heterogeneity within the continental lithosphere.
Incorporation of Legacy Seismic Refraction into Current Models in the Rocky Mountains
In anticipation of EarthScope and the challenges we face with acquiring a large amount of new data, I present here models that are developed using recent seismic refraction data from Deep Probe and CD-ROM jointly modeled with Legacy refraction data. The Legacy refraction data were acquired primarily from the 60’s and 70’s recording NTS blast and/or mine blasts. These Legacy were most recently compiled, modeled, and presented in Prodehl and Lipman (1989). The Moho thicknesses have been mapped most recently in the CD-ROM AGU Monograph, but these data have not been jointly modeled with newer data. Although these data had sparsely spaced recorders and sometime either were unreversed or only had on-end shots, they provide useful velocity constraints that can be easily incorporated with newly acquired data. This combination can provide more refined results as well as determine where there are additional targets of interest for the Rocky Mountain group. As a result this provides a database of information that can be built upon with future acquisition of seismic refraction data in the region.
Architecture, Physical State and Dynamics of the Western U.S. Interior as Revealed Through Electrical Conductivity Structure under EarthScope
P.E. Wannamaker and D. Hasterok (University of Utah)
M. Unsworth (University of Alberta)
Electrical conductivity provides independent understanding of deep hydration, thermal regime, fluidization/melting, lithospheric-scale fabric and faulting, and economic resource controls. Long-period magnetotelluric (MT) instruments collocated with passive seismometers of the Bigfoot array in the Rocky Mountain region will offer a 3-D view of these states and processes, using constraints from seismology, heat flow, structure, and geodesy. The potential of the method is well exemplified by studies to date. Since the early 1970’s, regional EM surveys have shown first-order high-conductivity axes below the transition from the Great Basin to the Colorado Plateau, and beneath the northern extension of the Rio Grande Rift, interpreted to represent modern rifting activity. The lower crust of the active regions is electrically conductive corresponding to a small fraction of hypersaline fluids from melt exsolution, thus implying weak rheology. This is nearly absent below the Colorado Plateau in keeping with its undeformed state. The depth to top of the conductor appears to lies at temperatures of 500-550 C and thus may be an isotherm proxy. The thermal profile of the central Great Basin and the Colorado Plateau below the lithosphere lies near the ACMA geotherm, and the upper mantle there appears horizontally isotropic and only weakly hydrated at most. In contrast, eastern Great Basin upper mantle appears substantially hotter, with significant probable melting and an abrupt, non-uniform vs depth transition eastward to the stable Colorado Plateau. Crustal-scale, shallowly dipping conductive fault zones ressembling detachments pervade the transition zone and sole into the lower crustal conductor. Lower crustal fabric inherited from the Proterozoic continental margin still appears to influence some deep electrical trends today but most of the structure represents the current thermal regime. An exception is the strong NACP conductor trend southward from Canada and terminating at the Cheyenne Belt; this conductor appears to be from metasedimentary graphite and sulphides caught up in the Trans Hudson orogen suture zone between Wyoming/Hearn and the Superior provinces.
Magnetotellurics and the Socorro Magma Body
Chester Weiss (Sandia National Laboratories)
Adam Schultz (Oregon State University)
The Socorro magma body (SMB) is a structurally and petrophysically enigmatic crustal feature which is highly amenable to electromagnetic interrogation due to its large electrical conductivity presumed to arise from the combined effects of elevated temperature and interconneted regions of partial melt. By using broadband magnetotelluric observations with instrumentation available through the EarthScope program, the PIs propose to investigate further the nature of the SMB, its relationship to the physiochemical state of the lithosphere, and its interaction with the shallow crust. In particular, the SMB represents an attractive target for collaboration between the goverment and academic sectors because of the potential for improved understanding of fault/fluid interactions and regional shallow water resources.
Progressive Proterozoic Growth of Southern Laurentia by Magmatic Stabilization of Lithosphere
From ~1.9 to 1.0 Ga, Laurentia grew by the successive addition of oceanic terranes and magmatic arcs to a long-lived “southern” compressive/transpressive plate margin. A new compilation of the southern Laurentian portion of Rodinia for the IGCP 440 project enables a sequential look at the growth of Laurentia, from which we examine the processes that transform initially thin crust and lithospheric mantle of juvenile terranes into stable continental lithosphere. The Archean cratons of Canada and the northwestern U.S. had stabilized as continental lithosphere prior to 2.5 Ga, were rifted about 2.1 Ga, then assembled into a large continental mass during 2.0-1.8 Ga Trans-Hudson orogenesis. Juvenile terrane accretion to southern Laurentia initiated with the Penokean orogeny at ~1.88-1.83 Ga, in which Archean basement and Paleoproterozoic supracrustal rocks were deformed and metamorphosed during collisions with oceanic arc terranes. This was followed by the successive accretion of NE-trending juvenile terranes, including the 1.78-1.68 Ga Mojave province (which incorporates reworked Archean and Paleoproterozoic basement), the 1.8-1.7 Ga Yavapai province and the 1.67-1.65 Mazatzal province. An underappreciated event was the addition of 1.5-1.3 Ga juvenile crust that now underlies much of the mid-continental U.S. from Texas through eastern Canada. This was likely a magmatic arc linked to ~1.45-1.35 Ga A-type magmatism that intruded and helped stabilize the older Proterozoic provinces. Accretion of juvenile crust to southern Laurentia culminated with the 1.3-1.0 Ga Grenville orogeny: the final stage in the growth of Rodinia prior to collapse and breakup at ~0.8-0.7 Ga. A principal focus of the new southern Laurentia map is the extent and ages of granitoid magmatism within the progressively assembled Proterozoic orogens. With each addition of juvenile crust, granitoid magmatism outlasted shortening deformation and invaded across province boundaries (defined by Nd data) to stitch young juvenile crust with older basement. This process is hypothesized to enhance cratonization by mechanical strengthening of the middle crust via pluton emplacement and reduction of anisotropy, strengthening of the lower crust via differentiation and development of a mafic residue, and stabilization of lithospheric mantle via thickening and de-densification due to basalt extraction.
Results from the LA RISTRA Seismic Array: Implications for the Earthscope Flexible Seismometer Array
Dave Wilson and Rick Aster (New Mexico Tech)
Mike West and Jim Ni (New Mexico State University)
Wei Gao and Steve Grand (University of Texas-Austin)
W. Scott Baldridge (Los Alamos National Laboratory)
Steve Semken (Arizona State University)
We present results from the Colorado Plateau/Rio Grande Rift/Great Plains seismic transect (LA RISTRA) experiment, a 950 km-long PASSCAL broadband seismic line with approximately 18 km station spacing deployed during 1999-2001 from Lake Powell, UT to Pecos, TX. LA RISTRA was designed to combine geophysical techniques with geological and geochemical information in order to investigate fundamental relationships between regional tectonic provinces and crust and upper mantle structure, and is a representative experiment addressing scientific issues appropriate for the Flexible Array component of USArray (LA RISTRA had 1/4 the number of broadband seismometers that will be available with the Flexible Array). Receiver function results show crustal thickness ranging from 45 to 50 km beneath both the Colorado Plateau and the Great Plains, thinning to a minimum of 35 km centered beneath the Rio Grande rift (RGR) axis. Inversion of surface wave data and tomographic inversion of teleseismic body-wave delay times show a broad low velocity region, also centered beneath the rift axis. These observations suggest that the lower crust and mantle lithosphere of the RGR have deformed symmetrically about the rift axis, indicating an essentially pure shear mode of lithospheric deformation. Upper mantle receiver function images show relatively flat discontinuities at 410 km and 670 km, indicating there is not a large-scale, deep-seated thermal anomaly beneath the rift. However, small-scale variations in upper mantle velocity, seen both in body wave tomography and surface wave analysis, indicate unexpected localized thermal or compositional variations that may influence small-scale convection and may be common in western U.S. upper mantle.
Upper Mantle Body Wave Tomography Beneath the Yellowstone Hotspot: Correlation with the Seismic Discontinuities
The mantle dynamics driving the Yellowstone hotspot is not well constrained by the current observations. The time-progressive trail of volcanism along the eastern Snake River Plain, the high 3He/4He ratio observed at Yellowstone, and the LIPs associated with the Columbia River and Steen Mountain basalts, all are broadly consistent with plume model. However, within the resolution of previous body wave tomography studies, a lack of low seismic velocity pipe extending through the transition zone is a provisional conclusion. A 3-dimensional P-wave tomographic study has been performed using the teleseismic travel-time residuals from the PASSCAL Yellowstone, Snake River Plain, Billings, University of Utah (UU), and USNSN stations. This array creates at surface apature of about 500 km in diameter centered at the Yellowstone Park, providing reasonably good ray coverage. Baseline array statics time shifts between these arrays have been calculated by using the UU and USNSN as a reference network of stations. The station elevation, basin depth and the Moho depth are taken into account to correct the travel-time residuals. To minimize the effects due to the irregular earthquake distribution, summary rays are formed. We use the LSQR algorithm to solve the inversion problem. A range of damping parameters is used to address the effects of regularization upon the velocity images. Our results show: 1 A hot pipe extends from the Yellowstone hotpot down to at least 410 km. Our most remarkable result is the -1% low velocity “tilted pipe” extending from beneath the Yellowstone Caldera down to at least 400 km (Figure 7b,c). This pipe intersects the 410 km discontinuity under Dillon, Montana, where a hot 410 is observed in the receiver function study of Fee and Dueker (Figure 8). A 1% P-velocity reduction at this depth is predicted to be a 200o k thermal anomaly [Cammarano et al, 2003]. This estimates is consistent with the 180o thermal prediction from the 410 topography. A temperature correlation between the body wave tomography (calculated from anelastic thermal derivatives) and the discontinuities topography (from Clapeyron slope) will be presented. 2. High velocity blobs exist in the Central Wyoming. These high velocities may represent the Wyoming lithosphere is shedding Rayleigh-Benard convective instabilities.
Science Interpretation Using Technology in National Parks
Linda Lutz-Ryan, Phil Zitcherman, and Judy Geniac (National Park Service)
Karl Karlstrom and Laura Crossey (University of New Mexico)
In conjunction with EarthScope (ES), the National Park Service (NPS) would like to assist in the development of media for EarthScope to educate the public in the meanings behind the data being collected by these scientists. These products will address a variety of audiences and their needs. By developing technology that is accessible to these audiences, the goal will be to establish a sense of project ownership among scientific, professional, and educational communities and the public so that even diverse groups of individuals and organizations can and will make contributions to EarthScope. They will also become general models that can be used at other parks and in a variety of geologic regions. Through this advanced technological media, ES and the NPS will enhance formal Earth Science education by promoting inquiry-based classroom investigations that focus on understanding the Earth and the interdisciplinary nature of the EarthScope experiment. A number of education technology methods are underway in the Intermountain Region of the NPS including; development of an “Earthcache” curriculum, melding geoscience and the sport of Geocaching, development of a virtual ranger device employing handheld and voice-activated database technology, production of web-based streaming video products, and the use of distance learning methods, in a number of languages to reach millions of audience members, far away from National Parks. These services will use the data collected directly from the local ES instrumentation for modeling and educating audiences onsite, while providing immediate connections to a scientific experiment being conducted, during their visit to the park.
This is the first of two workshops sponsored by NSF and hosted by the
University of New Mexico and New Mexico Tech on EarthScope in the Rocky Mountain region.
For more information, please contact Karl Karlstrom or
Rick Aster.
|
