The May 2014 West Salt Creek landslide in Mesa County, Colorado
Jonathan L. White, Senior Engineering Geologist, Colorado Geological Survey
On May 25th near the town of Collbran a very large rockslide rapidly moved almost 3 miles down the West Salt Creek valley, ultimately covering almost a square mile of the valley. The site is within the Plateau Creek basin below the northern flank of Grand Mesa, about 38 miles east of Grand Junction. Earlier the morning of the 25th, smaller precursor landslides occurred that blocked the flow of irrigation water. Tragically, while investigating the initial slide, three local men were killed when the main failure occurred at 5:45 pm. Their remains have not been recovered from landslide deposits that are up to 125 feet deep at the valley floor. Properly described as a sturzstrom rock avalanche, disaggregated shale and marlstone rock from the Green River Formation was pulverized and “flowed” in discrete avalanche surges. The most rapid avalanche pulse overtopped a 250-foot high ridgeline at an outside bend on the west side of the West Salt Creek valley. Preliminary estimates of maximum landslide velocity at that location, based empirically on the overtopped height, may be up to 75 miles per hour. The avalanche moved 39-million cubic yards of rock and soil down 2,100 feet of elevation and caused a 3-minute seismic wave train and 2.8 magnitude earthquake. Currently, a 2,800 by 700 by 500-foot rotated block of highly disturbed and potentially unstable rock remains immediately downslope from the headscarp. The back-tilt of the block has formed a large depression below the headscarp that has filled to form a large sag pond. The spill-over elevation is 15 feet above the current level, at which point the total capacity of the lake will be about 410 acre-ft. In addition to the long-term instability of the block, this raises additional concerns with mud-debris flows with regard to potential pond breaches during next year’s spring runoff, as well as mini-tsunamis if retrogressive failures occur and large rock blocks fall from the headscarp to displace the water.
This presentation will discuss the timeline of the slide, the initial emergency response and on-going landslide study, the geology of the area (and evidence of geologically recent and historic landslide activity), UAV photogrammetry and LiDAR imagery, and a preliminary assessment of the deposit and slide mechanics, as well as the future long-term hazards in the area where this valley-constrained rock avalanche occurred.
MOANA and HOBITSS Ocean Bottom Seismic Experiments: Information on Deep Structure, Anisotropy, and Slow Slip beneath New Zealand
Dr. Anne Sheehan, Professor of Geophysics, University of Colorado, Boulder
In my talk I will provide an overview of two recent ocean bottom seismic experiments designed to explore the deep structure and tectonics of New Zealand. The Marine Observations of Anisotropy Near Aotearoa (MOANA) experiment included a one year deployment of 30 broadband ocean bottom seismometers (OBS) installed off both coasts of the South Island of New Zealand from January 2009 to February 2010. Deployed with approximately 100 km spacing, this array of OBS has an aperture of approximately 1000 km spanning the Challenger Plateau, the South Island, to the Chatham Rise. I will give an overview of the experiment and research, including studies of mantle anisotropy and seismic tomography. On a much different scale, the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) experiment is a collaborative US-Japan-New Zealand experiment and includes 15 ocean bottom seismometers and 24 seafloor pressure gauges deployed at the Hikurangi subduction margin. The instruments were deployed in May 2014 and will remain on the seafloor for one year. The experiment was designed to record a slow-slip event at the subduction zone. Slow-slip events are earthquakes that take several weeks to happen, so they are better recorded by geodetic means such as GPS than by seismometers. In October 2014 a significant slow-slip event was recorded by Hikurangi onshore GPS. When the HOBITSS seafloor instruments are recovered in June 2015 we will see how well the slow slip event was recorded on the seafloor pressure gauges, which should allow us to better characterize the event.
A 30-minute video: the C.H. Birdseye USGS surveying expedition down the length of the Grand Canyon, Aug 1 – Oct. 19, 1923
Documenting changes in the landscape and glaciers of Glacier Bay National Park by recreating historical photography
both presented by: Don Becker, Video Producer & Archive Manager, U.S. Geological Survey, Lakewood, CO
Video: The C.H. Birdseye USGS surveying expedition down the Grand Canyon, 1923
From Mapping the Grand Canyon in 1923: The Birdseye Expedition
“In the summer of 1923, the USGS organized an expedition to make a new map of the Grand Canyon, which was the last stretch of the Colorado River that had not been accurately surveyed. Up until that time, only 27 men were known to have traversed the length of Marble and Grand canyons and of those, only two had any scientific knowledge (one of those two men was John Wesley Powell, the second director of the USGS, who led the first expedition down the river in 1869).
“This 251-mile stretch of the river extended from Lees Ferry to Diamond Creek. Claude Birdseye, who was the Chief Topographic Engineer of the USGS, was the expedition leader; Roland W. Burchard of the USGS was the expedition topographer; Eugene Clyde LaRue, the Chief Hydrologist for the USGS, was the expedition hydrologist and photographer; and Dr. Raymond C. Moore from the University of Kansas was the expedition geologist.
“Their party also included a cook, four boatmen (whose skill and nerve were crucial to the success of the expedition), a combination rodman/boatman, and four wooden boats.
“Birdseye was charged with making an unbroken level survey line through Marble and Grand canyons and running the survey line up side canyons. In addition, the party was to survey possible dam sites under the direction of LaRue (Westwood, 1992).
“The expedition launched from Lees Ferry on August 1, 1923. They completed the survey at Diamond Creek on October 13 and landed the boats at Needles, California on October 19, 1923.”
[The website contains much more interesting description and background about the expedition and a number of pictures, including a silent version of the 30-minute movie.]
The Grand Canyon survey party at Lees Ferry. Left to right: Leigh Lint, boatman; H.E. Blake, boatman; Frank Word, cook; C.H. Birdseye, expedition leader; R.C. Moore, geologist; R.W. Burchard, topographer; E.C. LaRue, hydraulic engineer; Lewis Freeman, boatman, and Emery Kolb, head boatman. Boatman Leigh Lint, “a beefy athlete who could tear the rowlocks off a boat…absolutely fearless,” later went to college and became an engineer for the USGS.
Documenting changes in the landscape and glaciers of Glacier Bay National Park by recreating historical photography
The primary purpose of this NPS – USGS demonstration research project is to DOCUMENT both long-term and short term changes in the glaciers within Glacier Bay National Park (GLBA) by comparing historical and modern photographs taken from identical locations. Approximately 190 historical photographs were obtained from several national archives. These photos dated between 1891 and 1980. Using the RV Capelin as a base of operations and for transportation around Glacier Bay, the locations of more than 60 photos were visited. This presentation will highlight a small sampling of the results of this cooperative activity, and the activities surrounding this effort.
Don Becker is a video producer for the USGS Office of Communications and Publishing for the last 35+ years and has worked on many video productions in the U.S., Canada and West Africa. He has hundreds of hours of experience filming from airplanes and helicopters, and is an accomplished cameraman and video editor as well. He has filmed along the Bering Sea in Alaska, the Colorado River in the Grand Canyon, the Everglades, and most places in between. Don worked as a video contractor to the USGS for many of his years based at the USGS EROS Data Center in Sioux Falls, SD. After becoming a USGS video producer in 2007, he transferred the video production facility and the USGS Video Archive to Denver in 2010. Don enjoys the outdoor activities that Colorado has to offer and his hobby is still photography.
The Search for Earth-like Planets
Dr. Tom Barclay, NASA Ames Research Center and the Bay Area Environmental Research Institute, California
Are we alone in the Universe? This is a question that has puzzled countless generations. While we not yet in a position say whether there is life out there, we are beginning to detect planets that remind us of home. The Kepler spacecraft has been used to identify several planets in the habitable zone of other stars – a region around a star where a planet could host liquid water at its surface given an appropriate atmosphere. Of particular note is Kepler-186f which is an Earth-sized planet that orbits within the habitable zone of a star that is smaller and cooler than the Sun. This talk will focus on the search for Earth-like worlds, discuss what we know about the planets we have found and look at what we don’t know right now but hope to learn from future NASA missions.
Tom Barclay was recently named Director of the Kepler K2 mission, to continue the search for exoplanets using the Kepler spacecraft.
The development of the Rio Grande rift between 25-10 Ma based on low temperature thermochronology
Shari Kelley, New Mexico Bureau of Geology and Mineral Resources, New Mexico Tech, Socorro, NM
Published apatite fission-track (AFT) ages from mountain ranges in Colorado and New Mexico record episodic 75-40 Ma (Laramide), 35-25 Ma (ignimbrite flareup), and 25-10 Ma (Rio Grande rift) exhumation of the southern Rocky Mountain region. New (U-Th)/He (AHe) dates from 32 of the AFT samples from mountain ranges bordering the Rio Grande rift are used to document near-synchronous exhumation of the rift flanks along the >850 km length of the rift between ~25 to 10 Ma. A geodynamic model that incorporates multistage rollback and foundering of the Farallon plate is proposed to explain the ignimbrite flareup and subsequent near-synchronous opening of the Rio Grande rift. The first stage of rollback led to the creation of the San Juan, Mogollon-Datil, and other large middle Cenozoic volcanic fields in Colorado and New Mexico. The second stage of foundering was associated with the 30 to 25 Ma detachment of remaining fragments of the Farallon slab. Removal of the slab triggered extension by focusing mantle convection in the vicinity of the break.
Dr. Shari Kelley is a geophysicist and field geologist with the New Mexico Bureau of Geology and Mineral Resources (NMBM) and Adjunct Faculty at New Mexico Tech in Socorro, New Mexico. Shari earned a B.S. in Geological Sciences at New Mexico State University and a Pd.D. in Geophysics at Southern Methodist University. Shari’s web responsibilities at the NMBM include creating and maintaining the Frequently Asked Questions and Virtual Geologic Tours portions of the Bureau’s webpage. Her research interests include building and maintaining New Mexico’s part of the National geothermal Database, Geothermal exploration in New Mexico, Application of apatite fission-track thermochronology to tectonic and landscape evolution
problems in the High Plains-Rio Grande rift-Rocky Mountain-Colorado Plateau region, and tectonic and landscape evolution of the Jemez Mountain volcanic field and the Sierra Blanca volcanic field, New Mexico. Shari has published more than seventy scientific papers and is co-author on more than thirty geologic maps.
Field Methods Past and Present,
by Jim Reed, Director of Research and Development, Rockware Incorporated.
Field Methods – Past, Present, & Future. A geological exploration project conducted in 1983 was duplicated in 2013. A comparison of these two projects shows that two-years of work in 1983 can now be performed in two-weeks. This dramatic increase in productivity is due to technological changes that have revolutionized field methods. These changes include GPS, GIS, and tablet computers. The accelerating pace of technological innovation promise even greater improvements. Drones, LIDAR, and augmented reality will fundamentally change how we collect and analyze data in the future.
Jim Reed has served as the Director of R&D at RockWare Incorporated since 1983. Prior to that, he worked as a field geologist for Freeport, AMAX, and Wold Nuclear. He received a BA in Earth & Planetary Sciences from Washington University in St. Louis, Missouri
The variability of hydrothermal ore deposits in the North American Cordilleran orogenic belt – insights into metallogeny from ore fluid analysis
by John Ridley, Department of Geosciences, Colorado State University, Fort Collins, CO
The Cordilleran orogenic belt of western North America has been the site of formation of a bewildering array of hydrothermal ore deposit types – Cu and Mo porphyries, high and low-sulfidation epithermal, polymetallic veins, orogenic gold veins, Carlin-type gold deposits and others. Although there is dispute in some cases over ore fluid sources, all deposit types are broadly related to magmatism in this convergent-margin setting. There are, however, few clear spatial or temporal patterns to where and when one rather than another type of deposit formed. Site specific processes of magmatic evolution, or of evolution of hydrothermal fluids after release from magma, may play roles. Some variability is further relatable to depth of erosion of magmatic centres. None of these factors can explain a first-order division of metallogeny between polymetallic (Cu, Au, Ag, Mo) ores and gold-only ores.
Ore fluids are typically studied as fluid inclusions in hydrothermal minerals. Laser-ablation inductively-couple plasma mass spectrometry (LA-ICP-MS) newly allows analysis of metal concentrations in inclusions. Interestingly, fluids of all ore deposit types appear to have broadly similar bulk compositions – relatively low-salinity and CO2-bearing. Few clear correlations between fluid metal content and ore metallogeny are apparent, but there are subtle differences between the contents of non-ore elements between multi-element ores and gold-only ores. Clues to the origins of the different metallogenies will likely come from understanding these differences in the context of magmatic and hence tectonic process in the history of the orogen.
John Ridley holds the MacCallum Chair of Economic Geology at the Department of Geosciences, Colorado State University. He took up this chair ten years ago after earlier holding faculty positions in Australia, Switzerland and Zimbabwe. He has recently published a new comprehensive textbook “Ore Deposit Geology”. His research uses field studies, structural geology, petrology, fluid inclusion studies and a broad gamut of geochemistry applied to ore deposits and their environments. He received his B.A. in Geology from The University of Cambridge (1978) and a Ph.D. from The University of Edinburgh (1982).
Presidential address: Heat Flow, Then and Now, Here and There
Paul Morgan, Colorado Geological Survey
Heat Flow: Then and Now, Here and There
Heat flow is the energy source that drives the earth’s internal engine, the little engine that could, working uphill against the process driven by the overwhelming energy source of the Sun. The average daily rate of energy gain and loss from the Sun (~340 W/m2) is 4,250 time greater than the average rate of energy loss from the Earth (~0.08 W/m2). Energy from the Sun drives atmospheric circulation and the hydrologic cycle resulting in erosion, generally working with gravity to move earth materials from higher elevations to lower elevations, and eventually to below sea level. Earth’s heat flow, counter-balances the effects of the Sun, rebuilding topography through global tectonics and volcanism.
Heat flow can rarely be directly observed at the surface – the energy flux is roughly equivalent to the light from a cell-phone screen on a medium intensity setting, but in the form of heat. Dramatic manifestations of heat flow are volcanoes, and, on a smaller scale, geysers and hot springs, but these are but a small fraction of the total heat budget. Geologists are probably more familiar with fossil results of heat flow such as metamorphism and hydrothermal ore deposits. There are reasons to believe that the earth is cooling: should we expect to see a signature of higher global heat loss in the rock record?
Heat flow from oceanic crust is dominated by very high heat flow at mid-ocean ridges, at which new oceanic lithosphere is created, decreasing as the sea-floor ages as it moves away from the ridges. This simple pattern is complicated by thermal convection in the crust until a blanket of sediments seals the crust from the circulation of sea-water. Continental heat flow is more complex than oceanic heat flow because it is generally older and more complex in its evolution, it is more chemically heterogeneous, its upper boundary is constantly changing, and heat-transfer by groundwater flow in the upper continental crust is common. The most significant difference is that a significant component of continental heat flow comes from heat generated by radiogenic decay of U, Th, and K in the crust, but the magnitude of this component is variable and unpredictable. In terranes dominated by large granitic plutons, a linear relation has been established between surface heat flow and surface heat production in the plutons. This relation is only valid for terranes dominated by large plutons, however. For heat-flow measurements from Archean terranes there is less scatter and a lower mean than for younger terranes suggesting a general lower heat production (U, Th, K) content in crust of Archean age. This suggests that either, 1) Archean crust was only generated with low heat production, or 2) high heat production Archean crust was recycled.
All planets and planetary bodies have heat flow and a thermal history. To date, the only extra-terrestrial heat-flow measurements made were during the Apollo mission on the Moon. Two data points were collected but unfortunately the results were sufficiently divergent that at least one more point is needed before any conclusions may be drawn. The next data should come from Mars, the InSIGHT mission, scheduled for launch in early 2016 with thermal data return from a single heat-flow experiment in 2017.
Paul Morgan received his formal education in Great Britain but his real education in the United States. He has been measuring heat flow since his doctoral studies in Cyprus and Kenya. His thermal interests range from laboratory and field measurements to heat flow theory, and from mantle xenoliths to geothermal studies on five of the seven continents and three of the eight (or nine) planets and the Moon. He is a member of the science team for the next NASA mission to Mars, InSIGHT, which will be measuring heat flow and seisAmicity on Mars. This will be the first robotic mission to place a scientific instrument on another planet. He is currently compiling and analyzing geothermal data in Colorado with the Colorado Geological Survey. December brings to an end his year as President of the Colorado Scientific Society.