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Sample records for active crater lake

  1. Crater Lake revealed

    USGS Publications Warehouse

    Ramsey, David W.; Dartnell, Peter; Bacon, Charles R.; Robinson, Joel E.; Gardner, James V.

    2003-01-01

    Around 500,000 people each year visit Crater Lake National Park in the Cascade Range of southern Oregon. Volcanic peaks, evergreen forests, and Crater Lake’s incredibly blue water are the park’s main attractions. Crater Lake partially fills the caldera that formed approximately 7,700 years ago by the eruption and subsequent collapse of a 12,000-foot volcano called Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama drastically changed the landscape all around the volcano and spread a blanket of volcanic ash at least as far away as southern Canada. Prior to the climactic event, Mount Mazama had a 400,000 year history of cone building activity like that of other Cascade volcanoes such as Mount Shasta. Since the climactic eruption, there have been several less violent, smaller postcaldera eruptions within the caldera itself. However, relatively little was known about the specifics of these eruptions because their products were obscured beneath Crater Lake’s surface. As the Crater Lake region is still potentially volcanically active, understanding past eruptive events is important to understanding future eruptions, which could threaten facilities and people at Crater Lake National Park and the major transportation corridor east of the Cascades. Recently, the lake bottom was mapped with a high-resolution multibeam echo sounder. The new bathymetric survey provides a 2m/pixel view of the lake floor from its deepest basins virtually to the shoreline. Using Geographic Information Systems (GIS) applications, the bathymetry data can be visualized and analyzed to shed light on the geology, geomorphology, and geologic history of Crater Lake.

  2. Correlation of volcanic activity with sulfur oxyanion speciation in a crater lake

    SciTech Connect

    Takano, B.

    1987-03-27

    The Yugama crater lake at Kusatsu-Shirane volcano, Japan, contains nearly 2200 tons (2800 parts per million) of polythionate ions (S/sub n/O/sub 6//sup 2 -/, where n = 4 to 9). Analytical data on lake water sampled before and during eruptions in 1982 showed that the concentrations of polythionates decreased and sulfate increased in response to the preeruption activities of the subaqueous fumaroles. These changes were observed 2 months before the first phreatic explosion on 26 October 1982. The monitoring of polythionates and sulfate in crater lake water is a promising means of anticipating potential volcanic eruption hazards.

  3. Leakage of active crater lake brine through the north flank at Rincon de la Vieja volcano, northwest Costa Rica, and implications for crater collapse

    USGS Publications Warehouse

    Kempter, K.A.; Rowe, G.L.

    2000-01-01

    The Active Crater at Rincon de la Vieja volcano, Costa Rica, reaches an elevation of 1750 m and contains a warm, hyper-acidic crater lake that probably formed soon after the eruption of the Rio Blanco tephra deposit approximately 3500 years before present. The Active Crater is buttressed by volcanic ridges and older craters on all sides except the north, which dips steeply toward the Caribbean coastal plains. Acidic, above-ambient-temperature streams are found along the Active Crater's north flank at elevations between 800 and 1000 m. A geochemical survey of thermal and non-thermal waters at Rincon de la Vieja was done in 1989 to determine whether hyper-acidic fluids are leaking from the Active Crater through the north flank, affecting the composition of north-flank streams. Results of the water-chemistry survey reveal that three distinct thermal waters are found on the flanks of Rincon de la Vieja volcano: acid chloride-sulfate (ACS), acid sulfate (AS), and neutral chloride (NC) waters. The most extreme ACS water was collected from the crater lake that fills the Active Crater. Chemical analyses of the lake water reveal a hyper-acidic (pH ~ 0) chloride-sulfate brine with elevated concentrations of calcium, magnesium, aluminum, iron, manganese, copper, zinc, fluorine, and boron. The composition of the brine reflects the combined effects of magmatic degassing from a shallow magma body beneath the Active Crater, dissolution of andesitic volcanic rock, and evaporative concentration of dissolved constituents at above-ambient temperatures. Similar cation and anion enrichments are found in the above-ambient-temperature streams draining the north flank of the Active Crater. The pH of north-flank thermal waters range from 3.6 to 4.1 and chloride:sulfate ratios (1.2-1.4) that are a factor of two greater than that of the lake brine (0.60). The waters have an ACS composition that is quite different from the AS and NC thermal waters that occur along the southern flank of Rincon

  4. Crater Lake: blue through time

    USGS Publications Warehouse

    Larson, Gary L.; Buktenica, Mark; Collier, Robert

    2003-01-01

    Blue is the color of constancy, hence the term true blue. The unearthly blueness of Crater Lake reflects its pristine character and gives scientists a focal point for studying human impacts on aquatic environments over long periods of time. Scientists with the U.S. Geological Survey (USGS), National Park Service, and Oregon State University have systematically studied the lake for the last two decades. Long-term monitoring of this lake is a priority of Crater Lake National Park and will continue far into the future.

  5. Crater lake and post-eruption hydrothermal activity, El Chichón Volcano, Mexico

    USGS Publications Warehouse

    Casadevall, Thomas J.; de la Cruz-Reyna, Servando; Rose, William I., Jr.; Bagley, Susan; Finnegan, David L.; Zoller, William H.

    1984-01-01

    Explosive eruptions of Volcán El Chichón in Chiapas, Mexico on March 28 and April 3–4, 1982 removed 0.2 km3 of rock to form a 1-km-wide 300-m-deep summit crater. By late April 1982 a lake had begun to form on the crater floor, and by November 1982 it attained a maximum surface area of 1.4 × 105 m2 and a volume of 5 × 106 m3. Accumulation of 4–5 m of rainfall between July and October 1982 largely formed the lake. In January 1983, temperatures of fumaroles on the crater floor and lower crater walls ranged from 98 to 115°C; by October 1983 the maximum temperature of fumarole emissions was 99°C. In January 1983 fumarole gas emissions were greater than 99 vol. % H2O with traces of CO2, SO2, and H2S. The water of the lake was a hot (T = 52–58°C), acidic (pH = 0.5), dilute solution (34,046 mg L−1 dissolved solids; Cl/S = 20.5). Sediment from the lake contains the same silicate minerals as the rocks of the 1982 pyroclastic deposits, together with less than 1% of elemental sulfur. The composition and temperature of the lake water is attributed to: (1) solution of fumarole emissions; (2) reaction of lake water with hot rocks beneath the lake level; (3) sediments washed into the lake from the crater walls; (4) hydrothermal fluids leaching sediments and formational waters in sedimentary rocks of the basement; (5) evaporation; and (6) precipitation.

  6. Interannual active layer thermal and dynamics evolution at the crater Lake CALM site, Deception Island (Antarctica).

    NASA Astrophysics Data System (ADS)

    Ramos, Miguel; Vieira, Gonzalo; Ángel De Pablo, Miguel; Molina, Antonio; Abramov, Andrey

    2015-04-01

    Deception Island, is an active strato-volcano on South Shetland Archipelago of Antarctica (62° 55' 0″ S, 60° 37' 0″ W), is a cold region with harsh remote and hostile environmental conditions. The permafrost and active layer existence, and the cold climate conditions together with volcanic material with height water content inside made this region of the Earth a perfect site to study the active layer and permafrost evolution involved in the Circumpolar Active Layer South (CALM-S) program. The active layer is measured in late January or firs february (during the end of the thaw period) at the "Crater Lake" CALM site (62°58'06.7''; 60°40'44.8'') on Deception Island, Antarctica, at the period 2006 to 2014 we obtained a mean annual value of 29,7±2 cm. In this paper, we describe the spatial active layer thickness distribution and report the reduction on the mean thickness between February 2006 and 2014. Below the active layer, permafrost could be also reported (with a mean thickness of 4.5± 0.5 m.) based on the temperature data acquired by sensors installed at different depth inside the soil; three different shallow boreholes was drilled (1.0 m., 1.6 m., 4.5 m. in depth) and we have been registered its temperature gradient at the 2010 to 2013 period. Here we use all those data 1) to describe the thermal behavior of the permafrost at the CALM site, and 2) to describe its evolution (aggradation/degradation) along fourteen years of continuous measurements. We develop this study, to known the thermal behavior of the permafrost and the active layer related with the air/soil interaction being one of the most important factors the snow layer that was measured by the installation of termo-snowmeters with the complement of an automatic digital camera during the 2008 to 2014 period. On the other hand, the pyroclastics soil materials has a very high values of water content then the latent heat in the freezing/thawing process controls the active layer evolution and the

  7. Numerical model of crater lake eruptions

    NASA Astrophysics Data System (ADS)

    Morrissey, M.; Gisler, G.; Weaver, R.; Gittings, M.

    2010-12-01

    We present results from a numerical investigation of subaqueous eruptions involving superheated steam released through a lake mimicking the volcanic setting at Mt. Ruapehu. The simulations were conducted using an adaptive mesh, multi-material, hydrodynamics code with thermal conduction SAGE, (Simple Adaptive Grid Eulerian). Parameters investigated include eruption pressure, lake level and mass of superheated vapor. The simulations produced a spectrum of eruption styles from vapor cavities to radial jets that resulted in hazards that ranged from small-scale waves to high amplitude surges that reached and cascaded over the edge of the crater rim. There was an overall tendency for lake surface activity to increase (including wave amplitude) with increasing mass of superheated vapor and eruption pressure. Surface waves were induced by the formation and collapse of a gas cavity. The collapse of the cavity is considered to play a major role in the characteristic features observed during a subaqueous eruption. The additional mass of superheated vapor produced a larger cavity that displaced a larger area of the lake surface resulting in fast moving surges upon the collapse of the cavity. High lake levels (>90 m) appear to suppress the development of explosive jetting activity when eruption pressures are <10 MPa. At very large eruption pressures (>10 MPa), vertical jets and radial ejections of steam and water can occur in water depths >90 m. Less explosive eruption styles can produce hazardous events such as lahars by the outward movement of surface waves over the crater rim.

  8. Volcano and earthquake hazards in the Crater Lake region, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.; Mastin, Larry G.; Scott, Kevin M.; Nathenson, Manuel

    1997-01-01

    Crater Lake lies in a basin, or caldera, formed by collapse of the Cascade volcano known as Mount Mazama during a violent, climactic eruption about 7,700 years ago. This event dramatically changed the character of the volcano so that many potential types of future events have no precedent there. This potentially active volcanic center is contained within Crater Lake National Park, visited by 500,000 people per year, and is adjacent to the main transportation corridor east of the Cascade Range. Because a lake is now present within the most likely site of future volcanic activity, many of the hazards at Crater Lake are different from those at most other Cascade volcanoes. Also significant are many faults near Crater Lake that clearly have been active in the recent past. These faults, and historic seismicity, indicate that damaging earthquakes can occur there in the future. This report describes the various types of volcano and earthquake hazards in the Crater Lake area, estimates of the likelihood of future events, recommendations for mitigation, and a map of hazard zones. The main conclusions are summarized below.

  9. Crater Lake Revealed: Using GIS to Visualize and Analyze Postcaldera Volcanoes Beneath Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Ramsey, D. W.; Robinson, J. E.; Dartnell, P.; Bacon, C. R.; Gardner, J. V.; Mayer, L. A.; Buktenica, M. W.

    2001-12-01

    formed at ~90, 250, and 480 years after the lake began to fill. Combining volume calculations determined with GIS and age information from the lake filling model, oldest to youngest Wizard Island minimum eruption rates are 8.4x106 m3/yr, 6.5x106 m3/yr, and 3.6x106 m3/yr. These are comparable to rates calculated for the central platform volcano using the same approach. The minimum eruption rate for the entire 4 km3 of postcaldera andesite erupted from ~90 to 480 years after caldera formation is 8.4x106 m3/yr, which is comparable to historic rates of lava effusion at arc volcanoes. The cessation of postcaldera volcanic activity at Crater Lake, ~4,900 years ago, is marked by subaqueous extrusion of a 0.074 km3 rhyodacite dome on the east flank of Wizard Island.\\J.V. Gardner et. al., 2001, USGS Water Resources Investigations Report 01-4046; http://walrus.wr.usgs.gov/pacmaps\\M. Nathenson et. al., 2001, Models for the Filling of Crater Lake, Oregon (this meeting)

  10. 36 CFR 7.2 - Crater Lake National Park.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Crater Lake National Park. 7... SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.2 Crater Lake National Park. (a) Fishing. Fishing in Crater Lake and park streams is permitted from May 20 through October 31. (b) Boating....

  11. 36 CFR 7.2 - Crater Lake National Park.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Crater Lake National Park. 7... SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.2 Crater Lake National Park. (a) Fishing. Fishing in Crater Lake and park streams is permitted from May 20 through October 31. (b) Boating....

  12. 36 CFR 7.2 - Crater Lake National Park.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Crater Lake National Park. 7... SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.2 Crater Lake National Park. (a) Fishing. Fishing in Crater Lake and park streams is permitted from May 20 through October 31. (b) Boating....

  13. 36 CFR 7.2 - Crater Lake National Park.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Crater Lake National Park. 7... SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.2 Crater Lake National Park. (a) Fishing. Fishing in Crater Lake and park streams is permitted from May 20 through October 31. (b) Boating....

  14. 36 CFR 7.2 - Crater Lake National Park.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Crater Lake National Park. 7... SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.2 Crater Lake National Park. (a) Fishing. Fishing in Crater Lake and park streams is permitted from May 20 through October 31. (b) Boating....

  15. Gale Crater: An Amazonian Impact Crater Lake at the Plateau/Plain Boundary

    NASA Technical Reports Server (NTRS)

    Cabrol, N. A.; Grin, E. A.

    1998-01-01

    Elysium Basin. According to the Amazonian age of Gale's floor, and the erosion direction in the crater, a flood from Elysium Basin is the most likely event to explain the material observed in Gale, and the formation of the last lake. This last flood may have been important enough to flood the central deposit up to about 1400 m above the crater floor, leaving two islands (non stream lined features) at the center of the deposit. Terrace spacing suggests a regular drop of the lake level in time. Fractures in terraces perpendicular to the shoreline can be interpreted either as: (a) the result of the drainage systems during the waning of the lake, or (b) traces of the pressure of an ice-covered sheet associated with subglacial drainage. The presence of a lake of such volume during the Amazonian period is one more evidence that water was still active on Mars relatively recently. Gale crater offers the rare opportunity to unveil a key-period of the martian history. The Amazonian might proved not as cold and dry as previously thought. The presence of large lakes and basins (Elysium Basin is large as the Mediterranean Sea), reinforces the model of an extensive water activity during the Amazonian that has still to be understood in the context of an assumed cooling and drying planet. The sediments and rocks that were left of this period in Gale keep the record of the climatic conditions of the Amazonian and the clues that are missing to understand the climatic evolution of Mars. In addition, Gale crater presents the advantage to be located at the plateau/plain boundary, which has never been studied and contains information about the two main martian geological units. As a conclusion, we propose a table that summarizes the worthiness of a mission in Gale crater, and the expected science return relative to the objectives to be met by the Surveyor Program. Additional information contained in the original.

  16. Speciation: Genomic Archipelagos in a Crater Lake.

    PubMed

    Ronco, Fabrizia; Salzburger, Walter

    2016-03-01

    The opening stages of speciation remain poorly understood, especially from a genomic perspective. The genomes of newly discovered crater-lake cichlid fish shed light on the early phases of diversification and suggest that selection acts on multiple genomic regions. PMID:26954438

  17. The CO2 Flux and the Chemistry of the Crater lake in 2013-2015 Evidence for the Enhanced Activity of El Chichon volcano, Mexico.

    NASA Astrophysics Data System (ADS)

    Taran, Y.; Jácome Paz, M. P.; Inguaggiato, S.; Collard, N.

    2015-12-01

    During 2013-2015, four CO2 flux surveys were performed in the El Chichon crater both, from the lake surface and from the soil of the crater. The chemistry of the lake water, as well as its physical parameters (surface area, depth, temperature) were also determined. The CO2 flux in 2014-2015 compared to the 2007-2008 data (Mazot et al., 2011, BV, 73: 423-441) increased almost one order of magnitude (from ~ 140 ton d-1 in 2008 to ~ 840 ton d-1 in 2014). During the last two years the lake became the largest for the whole time of observations with the maximum surface area more than 18 ha covering completely the NE fumarolic field and all thermal springs feeding the lake with mineralized water. Despite the maximum volume of the lake it was characterized in 2015 by the highest since 2007 chloride content (~2500 ppm) and temperature (34°C). A large degassing spot in the middle of the lake for the first time was observed in April 2015 with more than 10,000 g m-2 d-1 of the CO2 flux. These observations evidence that the volcano-hydrothermal system of El Chichon volcano came into a new stage of activity associated most probably with changes in the magmatic activity at depth.

  18. The CO2 flux and the chemistry of the crater lake in 2013-2015 evidence for the enhanced activity of El Chichon volcano, Mexico

    NASA Astrophysics Data System (ADS)

    Jácome Paz, Mariana Patricia; Taran, Yuri; Inguaggiato, Salvatore; Collard, Nathalie

    2016-04-01

    During 2013-2015, four CO2 flux surveys were performed in the El Chichon crater both, from the lake surface and from the soil of the crater floor. The chemistry of the lake water, as well as its physical parameters (surface area, depth, temperature) were also determined. The CO2 flux in 2014-2015 compared to the 2007-2008 data (Mazot et al., 2011, BV, 73: 423-441) increased almost one order of magnitude (from ~ 140 t/d in 2008 to ~ 840 t/d in 2014). During the last two years the lake became the largest for the whole time of observations with the maximum surface area more than 18 ha covering completely the NE fumarolic field and all thermal springs feeding the lake with mineralized water. Despite the maximum volume of the lake it was characterized in 2015 by the highest since 2007 chloride content (~2500 ppm) and temperature (34°C). A large degassing spot in the middle of the lake for the first time was observed in April 2015 with more than 10,000 g m-2 d-1 of the CO2 flux. These observations evidence that the volcano-hydrothermal system of El Chichon volcano came into a new stage of activity associated most probably with changes in the magmatic activity at depth.

  19. Chemical hazards from acid crater lakes

    NASA Astrophysics Data System (ADS)

    van Bergen, M. J.; Sumarti, S.; Heikens, A.; Bogaard, T. A.; Hartiyatun, S.

    2003-04-01

    Acid crater lakes, which are hosted by a considerable number of active volcanoes, form a potential threat for local ecosystems and human health, as they commonly contain large amounts of dissolved chemicals. Subsurface seepage or overflow can lead to severe deterioration of the water quality of rivers and wells, as observations around several of these volcanoes have shown. The Ijen crater lake in East Java (Indonesia) is a striking example, as this reservoir of hyperacid (pH<0.5) sulphate, chloride and fluoride-rich water is the source of a ca. 50 km long acid river that transports substantial quantities of potentially toxic elements. A downstream trend of increasing pH from <1 to 2.5-4 is largely due to dilution with moderately acid springs (pH= ca. 4) and neutral tributaries (pH= ca. 7) inside the Ijen caldera. Geochemical controls that regulate element transport are subject to seasonal fluctuations in rainfall. Long-term monitoring has shown that fluoride levels pose some of the most severe environmental threats. Its concentration decreases from ca. 1300 mg/kg in the lake to ca. 10 mg/kg in a coastal area downstream, where virtually all of the river water is used for irrigating rice fields and other cropland. Apart from serious problems for agriculture, our survey of 55 drinking water wells in the irrigation area shows that 50% contain fluoride above the 1.5 ppm WHO limit, in line with the observation that dental fluorosis is widespread among the ca. 100,000 residents of the area. A conspicuous spatial correlation between fluoride concentrations and the irrigation system suggest that long-term (century) infiltration of irrigation water may have affected the quality of groundwater. Fluorosis is also a problem in some villages within the caldera, where well water sources may have a more direct subsurface connection with the lake system. From our observations we conclude that water-quality monitoring is especially needed for health reasons in volcanic areas where

  20. Magmatic and hydrothermal controls on trace element output at active volcanoes as recorded by spherules of sulfur in acid crater lakes

    NASA Astrophysics Data System (ADS)

    Mason, P. R.; van Bergen, M.; Martinez, M.; Martinez, M.; Sumarti, S.; Sumarti, S.; Valdes, J.; Malavassi, E.; Sriwana, T.

    2001-12-01

    Volcanic crater lakes are a major site of condensation for volatile elements and associated trace elements produced by magmatic activity. Spherules of solid native sulfur up to several mm in diameter with sulfide inclusions (mainly corroded FeS) are common in the dense acidic waters of magmatically active lakes. They were most likely produced as hot gas (e.g. H2S or SO2) was released at the bottom of the lake creating turbulence in pools of liquid sulfur. Analysis of the spherules presents a new opportunity to estimate the magmatic output of a poorly studied group of trace elements including Se, Te, As, Sb and Hg that often present a major environmental hazard in volcanic areas. Sulfur spherules and acid lake waters were sampled from three active subduction-related volcanoes with differing stages of activity and degassing rates. Poás in Costa Rica hosts a highly dynamic crater lake with respect to volume and chemical composition. In contrast, the crater lakes at Kawah Ijen, East Java and Kawah Putih, West Java were more stable during the last 10 years but show some seasonal variations. Major and trace elements were determined in situ using electron microprobe and laser ablation ICP-MS techniques. Spherules are highly enriched in trace elements including Se (400-4000 μ g/g), Te (500-800 μ g/g), Sb (1-18 μ g/g) and As (30-510 μ g/g). The internal chemical homogeneity of the spherules supports rapid formation. Changes in lake chemistry may account in part for large differences in trace element content between samples from each volcanic center. Lower As/S and Sb/S ratios at Poás correspond to higher temperatures that promote an enhanced release of HCl vapor from the lake surface. Recycling of hydrothermal acid brines into the lake may also have affected these trace element ratios. High Se/S and Te/S ratios cannot be explained by mixing between mantle and shallow sources and probably reflect additional sulfur loss due to degassing of the magmatic source.

  1. Under trees and water at Crater Lake National Park, Oregon

    USGS Publications Warehouse

    Robinson, Joel E.; Bacon, Charles R.; Wayne, Chris

    2012-01-01

    Crater Lake partially fills the caldera that formed approximately 7,700 years ago during the eruption of a 12,000-ft-high volcano known as Mount Mazama. The caldera-forming, or climactic, eruption of Mount Mazama devastated the surrounding landscape, left a thick deposit of pumice and ash in adjacent valleys, and spread a blanket of volcanic ash as far away as southern Canada. Prior to the climactic event, Mount Mazama had a 400,000-year history of volcanic activity similar to other large Cascade volcanoes such as Mounts Shasta, Hood, and Rainier. Since the caldera formed, many smaller, less violent eruptions occurred at volcanic vents below Crater Lake's surface, including Wizard Island. A survey of Crater Lake National Park with airborne LiDAR (Light Detection And Ranging) resulted in a digital elevation map of the ground surface beneath the forest canopy. The average resolution is 1.6 laser returns per square meter yielding vertical and horizontal accuracies of ±5 cm. The map of the floor beneath the surface of the 1,947-ft-deep (593-m-deep) Crater Lake was developed from a multibeam sonar bathymetric survey and was added to the map to provide a continuous view of the landscape from the highest peak on Mount Scott to the deepest part of Crater Lake. Four enlarged shaded-relief views provide a sampling of features that illustrate the resolution of the LiDAR survey and illustrate its utility in revealing volcanic landforms and subtle features of the climactic eruption deposits. LiDAR's high precision and ability to "see" through the forest canopy reveal features that may not be easily recognized-even when walked over-because their full extent is hidden by vegetation, such as the 1-m-tall arcuate scarp near Castle Creek.

  2. CO2 flux and chemistry of El Chichón crater lake (México) in the period 2013-2015: Evidence for the enhanced volcano activity

    NASA Astrophysics Data System (ADS)

    Jácome Paz, Mariana P.; Taran, Yuri; Inguaggiato, Salvatore; Collard, Nathalie

    2016-01-01

    The CO2 flux from El Chichón crater in the period from 2014 to 2015 increased by a factor of 3 (from ~260 t d-1 to ~800 t d-1) compared to the 2007-2008 data. The mechanism triggering the CO2 flux from the lake surface has changed from being dominantly diffusive to mainly advective (bubbling). The Cl concentration was steadily decreasing during the last two decades in the Na-Cl boiling springs feeding the lake. Since 2013, for both lake and SP springs, the Cl concentration has increased up to the 2005 Cl concentration levels. A large degassing spot in the middle of the lake was found in April 2015 with a CO2 flux of more than 10,000 g m-2 d-1. These observations are the evidence of the onset of a new stage of activity within the volcano-hydrothermal system of El Chichón volcano associated most probably with changes in the magmatic activity at depth.

  3. Unusual bacterioplankton community structure in ultra-oligotrophic Crater Lake

    USGS Publications Warehouse

    Urbach, Ena; Vergin, Kevin L.; Morse, Ariel

    2001-01-01

    The bacterioplankton assemblage in Crater Lake, Oregon (U.S.A.), is different from communities found in other oxygenated lakes, as demonstrated by four small subunit ribosomal ribonucleic acid (SSU rRNA) gene clone libraries and oligonucleotide probe hybridization to RNA from lake water. Populations in the euphotic zone of this deep (589 m), oligotrophic caldera lake are dominated by two phylogenetic clusters of currently uncultivated bacteria: CL120-10, a newly identified cluster in the verrucomicrobiales, and ACK4 actinomycetes, known as a minor constituent of bacterioplankton in other lakes. Deep-water populations at 300 and 500 m are dominated by a different pair of uncultivated taxa: CL500-11, a novel cluster in the green nonsulfur bacteria, and group I marine crenarchaeota. b-Proteobacteria, dominant in most other freshwater environments, are relatively rare in Crater Lake (<=16% of nonchloroplast bacterial rRNA at all depths). Other taxa identified in Crater Lake libraries include a newly identified candidate bacterial division, ABY1, and a newly identified subcluster, CL0-1, within candidate division OP10. Probe analyses confirmed vertical stratification of several microbial groups, similar to patterns observed in open-ocean systems. Additional similarities between Crater Lake and ocean microbial populations include aphotic zone dominance of group I marine crenarchaeota and green nonsulfur bacteria. Comparison of Crater Lake to other lakes studied by rRNA methods suggests that selective factors structuring Crater Lake bacterioplankton populations may include low concentrations of available trace metals and dissolved organic matter, chemistry of infiltrating hydrothermal waters, and irradiation by high levels of ultraviolet light.

  4. Digital Data for Volcano Hazards in the Crater Lake Region, Oregon

    USGS Publications Warehouse

    Schilling, S.P.; Doelger, S.; Bacon, C.R.; Mastin, L.G.; Scott, K.E.; Nathenson, M.

    2008-01-01

    Crater Lake lies in a basin, or caldera, formed by collapse of the Cascade volcano known as Mount Mazama during a violent, climactic eruption about 7,700 years ago. This event dramatically changed the character of the volcano so that many potential types of future events have no precedent there. This potentially active volcanic center is contained within Crater Lake National Park, visited by 500,000 people per year, and is adjacent to the main transportation corridor east of the Cascade Range. Because a lake is now present within the most likely site of future volcanic activity, many of the hazards at Crater Lake are different from those at most other Cascade volcanoes. Also significant are many faults near Crater Lake that clearly have been active in the recent past. These faults, and historic seismicity, indicate that damaging earthquakes can occur there in the future. The USGS Open-File Report 97-487 (Bacon and others, 1997) describes the various types of volcano and earthquake hazards in the Crater Lake area, estimates of the likelihood of future events, recommendations for mitigation, and a map of hazard zones. The geographic information system (GIS) volcano hazard data layers used to produce the Crater Lake earthquake and volcano hazard map in USGS Open-File Report 97-487 are included in this data set. USGS scientists created one GIS data layer, c_faults, that delineates these faults and one layer, cballs, that depicts the downthrown side of the faults. Additional GIS layers chazline, chaz, and chazpoly were created to show 1)the extent of pumiceous pyroclastic-flow deposits of the caldera forming Mount Mazama eruption, 2)silicic and mafic vents in the Crater Lake region, and 3)the proximal hazard zone around the caldera rim, respectively.

  5. Clues to the Relative Timing of Lakes in Gale Crater

    NASA Astrophysics Data System (ADS)

    Dietrich, W. E.; Palucis, M. C.; Parker, T.; Rubin, D.; Lewis, K.; Sumner, D.; Williams, R. M. E.

    2014-07-01

    In Gale Crater two higher deltas appear to record the deposition into lakes associated with the cutting of Farah Vallis. At the entrance canyon to Mt. Sharp a possible back stepping fan/delta sequence may record a later rising lake level.

  6. Morphology, volcanism, and mass wasting in Crater Lake, Oregon

    USGS Publications Warehouse

    Bacon, C.R.; Gardner, J.V.; Mayer, L.A.; Buktenica, M.W.; Dartnell, P.; Ramsey, D.W.; Robinson, J.E.

    2002-01-01

    Crater Lake was surveyed nearly to its shoreline by high-resolution multibeam echo sounding in order to define its geologic history and provide an accurate base map for research and monitoring surveys. The bathymetry and acoustic backscatter reveal the character of landforms and lead to a chronology for the concurrent filling of the lake and volcanism within the ca. 7700 calibrated yr B.P. caldera. The andesitic Wizard Island and central-plattform volcanoes are composed of sequences of lava deltas that record former lake levels and demonstrate simultaneous activity at the two vents. Wizard Island eruptions ceased when the lake was ~80 m lower than at present. Lava streams from prominent channels on the surface of the central platform descended to feed extensive subaqueous flow fields on the caldera floor. The Wizard Island and central-platform volcanoes, andesitic Merriam Cone, and a newly discovered probable lava flow on the eastern floor of the lake apparently date from within a few hundred years of caldera collapse, whereas a small rhydacite dome was emplaced on the flank of Wizard Island at ca. 4800 cal. yr B.P. Bedrock outcrops on the submerged caldera walls are shown in detail and, in some cases, can be correlated with exposed geologic units of Mount Mazama. Fragmental debris making up the walls elsewhere consists of narrow talus cones forming a dendritic pattern that leads to fewer, wider ridges downslope. Hummocky topography and scattered blocks up to ~280 m long below many of the embayments in the caldera wall mark debris-avalanche deposits that probably formed in single events and commonly are affected by secondary failures. The flat-floored, deep basins contain relatively fine-grained sediment transported from the debris aprons by sheet-flow turbidity currents. Crater Lake apparently filled rapidly (ca. 400-750 yr) until reaching a permeable layer above glaciated lava identified by the new survey in the northeast caldera wall at ~1845 m elevation

  7. Geologic Map of Mount Mazama and Crater Lake Caldera, Oregon

    USGS Publications Warehouse

    Bacon, Charles R.

    2008-01-01

    Crater Lake partly fills one of the most spectacular calderas of the world, an 8-by-10-km basin more than 1 km deep formed by collapse of the volcano known as Mount Mazama (fig. 1) during a rapid series of explosive eruptions about 7,700 years ago. Having a maximum depth of 594 m, Crater Lake is the deepest lake in the United States. Crater Lake National Park, dedicated in 1902, encompasses 645 km2 of pristine forested and alpine terrain, including the lake itself, virtually all of Mount Mazama, and most of the area of the geologic map. The geology of the area was first described in detail by Diller and Patton (1902) and later by Williams (1942), whose vivid account led to international recognition of Crater Lake as the classic collapse caldera. Because of excellent preservation and access, Mount Mazama, Crater Lake caldera, and the deposits formed by the climactic eruption constitute a natural laboratory for study of volcanic and magmatic processes. For example, the climactic ejecta are renowned among volcanologists as evidence for systematic compositional zonation within a subterranean magma chamber. Mount Mazama's climactic eruption also is important as the source of the widespread Mazama ash, a useful Holocene stratigraphic marker throughout the Pacific Northwest, adjacent Canada, and offshore. A detailed bathymetric survey of the floor of Crater Lake in 2000 (Bacon and others, 2002) provides a unique record of postcaldera eruptions, the interplay between volcanism and filling of the lake, and sediment transport within this closed basin. Knowledge of the geology and eruptive history of the Mount Mazama edifice, greatly enhanced by the caldera wall exposures, gives exceptional insight into how large volcanoes of magmatic arcs grow and evolve. Lastly, the many smaller volcanoes of the High Cascades beyond the limits of Mount Mazama are a source of information on the flux of mantle-derived magma through the region. General principles of magmatic and eruptive

  8. Warm Brine Lakes in Craters of Active Mud Volcanoes, Menes Caldera off NW Egypt: Evidence for Deep-Rooted Thermogenic Processes

    NASA Astrophysics Data System (ADS)

    Dupré, S.; Mascle, J.; Foucher, J. P.; Woodside, J. M.; Pierre, C.

    2015-12-01

    The Menes caldera is a fault-controlled depression (~8 km in diameter) at ~3,000 m water depth in the western province of the Nile deep-sea fan off NW Egypt, comprising seven mud volcanoes (MVs) of which two are active. Based on multichannel and chirp seismic data, temperature profiles, and high-resolution bathymetric data collected during several oceanographic expeditions, the present study investigates factors controlling mud volcano morphology, the geometry of feeder channels, and the origin of emitted fluids (Dupré et al. 2014). The active Cheops and Chephren mud volcanoes are 1,500 m wide with subcircular craters at their summits, about 250 m in diameter, generally a few tens of metres deep, and filled with methane-rich muddy brines with temperatures reaching 42 °C and 57 °C respectively. Deployments of CTDs and corers with attached temperature sensors tracked these warm temperatures down to almost 0.5 km depth below the brine lake surface at the Cheops mud volcano, in a feeder channel probably only a few tens of metres wide. Thermogenic processes involve the dissolution of Messinian evaporites by warm fluids likely sourced even deeper, i.e. 1.7 and 2.6 km below the seabed at the Cheops and Chephren MVs respectively, and which ascend along listric faults. Seepage activity appears broadly persistent since the initiation of mud volcanism in the Early Pliocene, possibly accompanied by lateral migration of feeder channels.

  9. Warm brine lakes in craters of active mud volcanoes, Menes caldera off NW Egypt: evidence for deep-rooted thermogenic processes

    NASA Astrophysics Data System (ADS)

    Dupré, Stéphanie; Mascle, Jean; Foucher, Jean-Paul; Harmegnies, François; Woodside, John; Pierre, Catherine

    2014-06-01

    The Menes caldera is a fault-controlled depression (~8 km in diameter) at ~3,000 m water depth in the western province of the Nile deep-sea fan off NW Egypt, comprising seven mud volcanoes (MVs) of which two are active. Based on multichannel and chirp seismic data, temperature profiles, and high-resolution bathymetric data collected during the 2000 Fanil, 2004 Mimes and 2007 Medeco2 expeditions, the present study investigates factors controlling MV morphology, the geometry of feeder channels, and the origin of emitted fluids. The active Cheops and Chephren MVs are 1,500 m wide with subcircular craters at their summits, about 250 m in diameter, generally a few tens of metres deep, and filled with methane-rich muddy brines with temperatures reaching 42 °C and 57 °C respectively. Deployments of CTDs and corers with attached temperature sensors tracked these warm temperatures down to almost 0.5 km depth below the brine lake surface at the Cheops MV, in a feeder channel probably only a few tens of metres wide. Thermogenic processes involve the dissolution of Messinian evaporites by warm fluids likely sourced even deeper, i.e. 1.7 and 2.6 km below the seabed at the Cheops and Chephren MVs respectively, and which ascend along listric faults. Seepage activity appears broadly persistent since the initiation of mud volcanism in the Early Pliocene, possibly accompanied by lateral migration of feeder channels.

  10. Geophysical Signature of the Lake Bosumtwi Impact Crater, Ghana

    NASA Astrophysics Data System (ADS)

    Karp, T.; Milkereit, B.; Janle, P.; Danuor, S. K.; Berckhemer, H.; Pohl, J.; Scholz, C. A.

    2001-12-01

    The Bosumtwi impact structure in Ghana has an age of 1.07 Ma, a rim-to-rim diameter of 10.5 km, and is the youngest large impact crater on earth. It is the source crater of the Ivory Coast tectites (Koeberl et al., Geoch. Cosmoch. Acta 61, 1997). The central part of the structure is filled by Lake Bosumtwi. Marine seismic studies were conducted to investigate crater morphology (thickness of post-impact sediments, depth and shape of central uplift). Refraction seismic (OBH and PDAS seismometer) and multichannel reflection data were collected to image the complex subsurface crater structure. Results from integrated modelling reveal low P-wave velocities in the young post-impact sediments (less than 1.8 km/s) and a prominent central uplift structure about 120 m high. The total thickness of the sediments does not exceed 350 m. Gravity and magnetic surveys complement regional airborne geophysical data across the structure (Plado et al., Meteor. & Planet. Sc., 35, 2000). Gravity data from 160 stations on land around the lake show the expected minimum resulting from the sedimentary filling of the lake, low density impact formations, brecciated and fragmented basement. In the fall of 2001 additional gravity measurements will be carried out on the lake to better delineate prominent anomalies associated with the central structure. The magnetic anomalies are attributed to remanent magnetization of melt, breccias and footwall complex. Further integration of different data sets will help to develop a detailed lithological model of the crater's subsurface structure. The geophysical data confirm that the Lake Bosumtwi structure provides an ideal setting for drilling of a young and large impact crater.

  11. Deglacial and postglacial evolution of the Pingualuit Crater Lake basin, northern Québec (Canada)

    NASA Astrophysics Data System (ADS)

    Desiage, Pierre-Arnaud; Lajeunesse, Patrick; St-Onge, Guillaume; Normandeau, Alexandre; Ledoux, Grégoire; Guyard, Hervé; Pienitz, Reinhard

    2015-11-01

    The Pingualuit Crater, located in the Ungava Peninsula (northern Québec, Canada) is a 1.4-Ma-old impact crater hosting a ~ 245-m-deep lake. The lake has a great potential to preserve unique paleoclimatic and paleoecological sedimentary records of the last glacial/interglacial cycles in the terrestrial Canadian Arctic. In order to investigate the stratigraphy in the lake and the late Quaternary glacial history of the Pingualuit Crater, this study compiles data from three expeditions carried out in May 2007 (~ 9-m-long sediment core), in August 2010 (~ 50 km of seismic lines), and in September 2012 (high-resolution terrestrial LiDAR topography of the inner slopes). Despite the weak penetration (~ 10 m) of the 3.5-kHz subbottom profiling caused by the presence of boulders in the sedimentary column, seismic data coupled with the stratigraphy established from the sediment core enabled the identification of two glaciolacustrine units deposited during the final stages of the Laurentide Ice Sheet (LIS) retreat in the crater. Two episodes of postglacial mass wasting events were also identified on the slopes and in the deep basin of the crater. The high-resolution topography of the internal slopes of the crater generated from the LiDAR data permitted the confirmation of a paleolake level at 545 m and determination of the elevation of drainage outlets. Together with the mapping of glacial and deglacial landforms from air photographs, the LiDAR data allowed the development of a new deglaciation and drainage scenario for the Pingualuit Crater Lake and surrounding area. The model proposes three main phases of lake drainage, based on the activation of seven outlets following the retreat of the LIS front toward the southwest. Finally, as opposed to other high-latitude crater lake basins such as Lake El'gygytgyn or Laguna Potrok Aike where high-resolution paleoclimatic records were obtained owing to high sediment accumulation rates, the seismic data from the Pingualuit Crater Lake

  12. Models for the Filling of Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Nathenson, M.; Bacon, C. R.; Gardner, J. V.

    2001-12-01

    Crater Lake partially fills, to a depth of 593 m, the 10-km-diameter, 1200-m-deep caldera formed by collapse of Mount Mazama volcano. The lake receives water from direct precipitation and inflow from the caldera walls and loses water by surface evaporation and leakage. No streams flow from Crater Lake. A high-resolution multibeam echo sounding survey of the lake floor conducted in 2000 (Gardner et al., 2001) revealed seven drowned beaches between 1849 and 1878 m elevation (reference lake elevation is 1883 m). The beaches are thought to reflect drier periods in the lake's history since the climactic, caldera-forming eruption of Mount Mazama, approximately 7,700 years ago. The shallowest drowned beach at 1878 m represents the deepest part of a wave-cut platform up to 100 m wide, substantially wider than any of the beaches, where erodible talus or intensely altered rocks are present. The great width of the platform compared to the width of the drowned beaches indicates that the lake has mostly been near its current level during the lake's history. Unambiguous evidence of former highstands above 1883 m has not been reported. In order to explain the occurrence of the drowned beaches and their relatively narrow depth range, leakage through the caldera walls must vary with depth and cannot occur just at the lake bottom or at the modern lake level. A reasonable model is that leakage is proportional to elevation above the bottom of the lake. Recognition that there is a thick layer of relatively permeable debris resting on glaciated lava in the northeast caldera wall above an elevation of 1845 m suggests a variant of this model where leakage is proportional to elevation above 1845 m. Climate studies indicate that Crater Lake began to fill during a dry period. Assuming that precipitation at that time was 70% of modern and that the beach at 1853 m (the deeper beach is somewhat suspect) corresponds to this amount of precipitation, a combination of the above leakage models is

  13. Detecting long-term hydrological patterns at Crater Lake, Oregon

    USGS Publications Warehouse

    Peterson, D.L.; Silsbee, D.G.; Redmond, Kelly T.

    1999-01-01

    Tree-ring chronologies for mountain hemlock (Tsuga mertensiana) were used to reconstruct the water level of Crater Lake, a high-elevation lake in the southern Cascade Range of Oregon. Reconstructions indicate that lake level since the late 1980s has been lower than at any point in the last 300 years except the early 1930s to mid 1940s. Lake level was consistently higher during the Little Ice Age than during the late 20th century; during the late 17th century, lake level was up to 9 m higher than recent (1980s and 1990s) low levels, which is consistent with paleoclimalic reconstructions of regional precipitation and atmospheric pressure. Furthermore, instrumental data available for the 20th century suggest that there are strong teleconnections among atmospheric circulation (e.g., Pacific Decadal Oscillation), tree growth, and hydrology in southern Oregon. Crater Lake is sensitive to interannual, interdecadal and intercentenary variation in precipitation and atmospheric circulation, and can be expected to track both short-term and longterm variation in regional climatic patterns that may occur in the future.

  14. 2005 Crater Lake Formation, Lahar, Acidic Flood, and Gas Emission From Chiginagak Volcano, Alaska

    NASA Astrophysics Data System (ADS)

    Schaefer, J. R.; Scott, W. E.; McGimsey, R. G.; Jorgenson, J.

    2005-12-01

    A 400-m-wide crater lake developed in the formerly snow-and-ice-filled crater of Mount Chiginagak volcano sometime between August 2004 and June 2005, presumably due to increased heat flux from the hydrothermal system. We are also evaluating the possible role of magma intrusion and degassing. In early summer 2005, clay-rich debris and an estimated 5.6 million cubic meters of acidic water from the crater exited through tunnels in the base of a glacier that breaches the south crater rim. Over 27 kilometers downstream, the acidic waters of the flood reached approximately 1.5 meters above current water levels and inundated an important salmon spawning drainage, acidifying at least the surface water of Mother Goose Lake (approximately 1 cubic kilometer in volume) and preventing the annual salmon run. No measurements of pH were taken until late August 2005. At that time the pH of water sampled from the Mother Goose Lake inlet, lake surface, and outlet stream (King Salmon River) was 3.2. Defoliation and leaf damage of vegetation along affected streams, in areas to heights of over 70 meters in elevation above flood level, indicates that a cloud of detrimental gas or aerosol accompanied the flood waters. Analysis of stream water, lake water, and vegetation samples is underway to better determine the agent responsible for the plant damage. This intriguing pattern of gas-damaged vegetation concentrated along and above the flood channels is cause for further investigation into potential hazards associated with Chiginagak's active crater lake. Anecdotal evidence from local lodge owners and aerial photographs from 1953 suggest that similar releases occurred in the mid-1970s and early 1950s.

  15. Evidence for a Noachian-Aged Ephemeral Lake in Gusev Crater, Mars

    NASA Technical Reports Server (NTRS)

    Ruff, S. W.; Niles, P. B.; Alfano, F.; Clarke, A. B.

    2014-01-01

    Gusev crater was selected as the landing site for the Spirit rover because of the likelihood that it contained an ancient lake. Although outcrops rich in Mg-Fe carbonate dubbed Comanche were discovered in the Noachian-aged Columbia Hills, they were inferred to result from volcanic hydrothermal activity. Spirit encountered other mineral and chemical indicators of aqueous activity, but none was recognized as definitive evidence for a former lake in part because none was associated with obvious lacustrine sedimentary deposits. However, water discharge into Martian crater basins like Gusev may have been episodic, producing only small amounts of sediment and shallow ephemeral lakes. Evaporative precipitation from such water bodies has been suggested as a way of producing the Mg- and Fe-rich carbonates found in ALH84001 and carbonates and salts in some nakhlites a hypothesis we examine for the Comanche carbonate.

  16. Effect of glacier ablation on the Snettisham Hydroelectric Project, Long Lake and Crater Lake Basins, Alaska

    USGS Publications Warehouse

    Sloan, C.E.; Emery, P.A.; Fair, Diana

    1986-01-01

    Long Lake Basin in the Snettisham Project Area southeast of Juneau, Alaska, yields water used for the production of hydroelectric power. Development of adjacent Crater Lake is planned to increase the Project 's generating capacity. Estimates of the hydroelectric potential of the lakes are based on streamflow records which are influenced by glaciers that cover 25% of the combined basins. Analysis of streamflow records shows that the quality and extent of records in the area are sufficient to predict flow from the Crater Creek basin with a fairly high degree of confidence. Comparison of aerial photographs indicates that glacier ablation and recession have been continuous since at least 1929. Estimates of ice-volume change from photogrammetric measurements indicate that less than 2.5% of the average runoff from the basins of Long and Crater Lakes has been from reduction in glacier-ice storage. (Author 's abstract)

  17. Late Quaternary slip rate and seismic hazards of the West Klamath Lake fault zone near Crater Lake, Oregon Cascades

    USGS Publications Warehouse

    Bacon, C.R.; Lanphere, M.A.; Champion, D.E.

    1999-01-01

    Crater Lake caldera is at the north end of the Klamath graben, where this N10??W-trending major Basin and Range structure impinges upon the north-south-trending High Cascades volcanic arc. East-facing normal faults, typically 10-15 km long, form the West Klamath Lake fault zone, which bounds the graben on its west side. The fault zone terminates on the south near the epicentral area of the September 1993 Klamath Falls earthquakes. It continues north past Crater Lake as the Annie Spring fault, which is within ~1 km of the west caldera rim, and Red Cone Spring fault. We have determined a long-term vertical slip rate of 0.3 mm/yr for these two faults using high-precision K-Ar and 40Ar/39Ar age measurements on offset lava flows ranging in age from ca. 35 to 300 ka. Holocene offset reported by Hawkins et al. and epicenters of eight MW 2 earthquakes in 1994 and 1995 indicate that the West Klamath Lake fautl zone is active. Empirical relations between earthquake magnitudes and scarp heights or fault lengths suggest that the fault zone is capable of producing earthquakes as large as MW 7 1/4 . Earthquakes on these or other faults of the zone could trigger landslides and rockfalls from the walls of the caldera, possibly resulting in large waves on Crater Lake.

  18. Thermal, chemical, and optical properties of Crater Lake, Oregon

    USGS Publications Warehouse

    Larson, G.L.; Hoffman, R.L.; McIntire, D.C.; Buktenica, M.W.; Girdner, S.F.

    2007-01-01

    Crater Lake covers the floor of the Mount Mazama caldera that formed 7700 years ago. The lake has a surface area of 53 km2 and a maximum depth of 594 m. There is no outlet stream and surface inflow is limited to small streams and springs. Owing to its great volume and heat, the lake is not covered by snow and ice in winter unlike other lakes in the Cascade Range. The lake is isothermal in winter except for a slight increase in temperature in the deep lake from hyperadiabatic processes and inflow of hydrothermal fluids. During winter and spring the water column mixes to a depth of about 200-250 m from wind energy and convection. Circulation of the deep lake occurs periodically in winter and spring when cold, near-surface waters sink to the lake bottom; a process that results in the upwelling of nutrients, especially nitrate-N, into the upper strata of the lake. Thermal stratification occurs in late summer and fall. The maximum thickness of the epilimnion is about 20 m and the metalimnion extends to a depth of about 100 m. Thus, most of the lake volume is a cold hypolimnion. The year-round near-bottom temperature is about 3.5??C. Overall, hydrothermal fluids define and temporally maintain the basic water quality characteristics of the lake (e.g., pH, alkalinity and conductivity). Total phosphorus and orthophosphate-P concentrations are fairly uniform throughout the water column, where as total Kjeldahl-N and ammonia-N are highest in concentration in the upper lake. Concentrations of nitrate-N increase with depth below 200 m. No long-term changes in water quality have been detected. Secchi disk (20-cm) clarity varied seasonally and annually, but was typically highest in June and lowest in August. During the current study, August Secchi disk clarity readings averaged about 30 m. The maximum individual clarity reading was 41.5 m in June 1997. The lowest reading was 18.1 m in July 1995. From 1896 (white-dinner plate) to 2003, the average August Secchi disk reading was

  19. High Spatio-Temporal Resolution Observations of Crater-Lake Surface Temperatures at Kawah Ijen Volcano, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Lewicki, J. L.; Caudron, C.; van Hinsberg, V.; Bani, P.; Hilley, G. E.; Kelly, P. J.

    2015-12-01

    Subaqueous volcanic eruptions comprise only 8% of all recorded eruptions in historical time, but have caused ~20% of fatalities associated with volcanic activity during this time (Mastin and Witter, 2000). Crater lakes, however, act as calorimeters, absorbing heat from intruding magma and integrating it over space and time and thus offer a unique opportunity to monitor volcanic activity. Kawah Ijen is a composite volcano located on east Java, Indonesia, whose crater hosts the largest natural hyperacidic lake (27 x 106 m3; pH <1) on Earth. As part of an international workshop on Kawah Ijen in September 2014, we tested a novel approach for mapping and monitoring variations in crater-lake apparent surface temperatures at high spatial (~30 cm) and temporal (every two minutes) resolution. We used a ground-based thermal infrared (TIR) camera from the crater rim to collect a set of visible imagery around the crater during the daytime and a time series of co-located visible and TIR imagery at one location from pre-dawn to daytime. We processed daytime visible imagery with the Structure-from-Motion photogrammetric method to create a digital elevation model onto which the time series of TIR imagery was orthorectified and georeferenced. Lake apparent surface temperatures typically ranged from ~21 to 28oC. At two locations, apparent surface temperatures were ~ 7 and 9 oC less than in-situ lake temperature measurements at 1.5 and 5 m depth, respectively. We observed large spatio-temporal variations in lake apparent surface temperatures, which were likely associated with wind-driven evaporative cooling of the lake surface. Our approach shows promise for continuous monitoring of crater-lake surface temperatures, particularly if the TIR camera is deployed as part of a permanent station with ancillary meteorological measurements to help distinguish temperature variations associated with atmospheric processes from those at depth within the lake and volcano.

  20. Detection of recycled marine sediment components in crater lake fluids using 129I

    NASA Astrophysics Data System (ADS)

    Fehn, U.; Snyder, G. T.; Varekamp, J. C.

    2002-06-01

    Crater lakes provide time-integrated samples of volcanic fluids, which may carry information on source components. We tested under what circumstances 129I concentrations can be used for the detection of a signal derived from the recycling of marine sediments in subduction zone magmatism. The 129I system has been successfully used to determine origin and pathways in other volcanic fluids, but the application of this system to crater lakes is complicated by the presence of anthropogenic 129I, related to recent nuclear activities. Results are reported from four crater lakes, associated with subducting crust varying in age between 23 and 98 Ma. The 129I/I ratios determined for Copahue, Argentina, ( 129I/I=700×10 -15) and White Island, New Zealand, ( 129I/I=284×10 -15) demonstrate the presence of iodine in the crater lakes that was derived from recycled marine sediments. A comparison to the ages of the subducted sediments in these two cases indicates that the ratios likely reflect iodine remobilization from the entire sediment column that was undergoing subduction. While the 129I signals in Poás and Rincón de la Vieja, Costa Rica also demonstrate the presence of recycled iodine, the relatively high percentage of meteoric water in these lakes prevents a reliable determination of source ages. The observed high concentrations of iodine and 129I/I ratios substantially below current surface values strongly argue for the presence of recycled marine components in the arc magmas of all four cases. Components from subducted marine sediments can be quantified and related to specific parts of the sediment column in cases where the iodine concentration in the lake waters exceeds 5 μM.

  1. Hydrogeochemical surveillance at El Chichón volcano crater lake, Chiapas, Mexico

    NASA Astrophysics Data System (ADS)

    Armienta, María Aurora; De la Cruz-Reyna, Servando; Ramos, Silvia; Ceniceros, Nora; Cruz, Olivia; Aguayo, Alejandra; Arcega-Cabrera, Flor

    2014-09-01

    El Chichón volcano has an eruptive record of at least 12 major eruptions in the Holocene, the latest one in March-April 1982 causing the worst volcanic disaster in the history of Mexico. After about 6 centuries of quiescence, this eruption destroyed a large dome and opened a 1 km wide crater. A lake, formed within the crater shortly after the eruption, has been an important source of information about the evolution of the post-eruptive processes. The fluctuations of the crater lake water physicochemical parameters, observed since 1983, have allowed in identifying hydrothermal waters and H2S-rich gases, influenced by tectonic and meteorological effects, as the main contributors to its composition. Here we propose some methods to help in assessing the state of the volcano derived from the relative contribution of these factors as an easy to implement volcanic surveillance method in potentially active volcanoes with crater lakes, or other volcano-influenced water sources.

  2. An Igneous Origin for Features of a Candidate Crater-Lake System in Western Memnonia, Mars

    NASA Technical Reports Server (NTRS)

    Leverington, D. W.; Maxwell, T. A.

    2004-01-01

    The association of channels, inner terraces, and delta-like features with Martian impact craters has previously been interpreted as evidence in favor of the past existence of crater lakes on Mars. However, examination of a candidate crater-lake system in western Memnonia suggests instead that its features may have formed through igneous processes involving the flow and ponding of lava. Accumulations of material in craters and other topographic lows throughout much of the study region have characteristics consistent with those of volcanic deposits, and terraces found along the inner flanks of some of these craters are interpreted as having formed through drainage or subsidence of volcanic materials. Channels previously identified as inlets and outlets of the crater-lake system are interpreted instead as volcanic rilles. These results challenge previous interpretations of terrace and channel features in the study region and suggest that candidate crater lakes located elsewhere should be reexamined.

  3. Ultraviolet radiation and bio-optics in Crater Lake, Oregon

    USGS Publications Warehouse

    Hargreaves, B.R.; Girdner, S.F.; Buktenica, M.W.; Collier, R.W.; Urbach, E.; Larson, G.L.

    2007-01-01

    Crater Lake, Oregon, is a mid-latitude caldera lake famous for its depth (594 m) and blue color. Recent underwater spectral measurements of solar radiation (300-800 nm) support earlier observations of unusual transparency and extend these to UV-B wavelengths. New data suggest that penetration of solar UVR into Crater Lake has a significant ecological impact. Evidence includes a correlation between water column chlorophyll-a and stratospheric ozone since 1984, the scarcity of organisms in the upper water column, and apparent UV screening pigments in phytoplankton that vary with depth. The lowest UV-B diffuse attenuation coefficients (K d,320) were similar to those reported for the clearest natural waters elsewhere, and were lower than estimates for pure water published in 1981. Optical proxies for UVR attenuation were correlated with chlorophyll-a concentration (0-30 m) during typical dry summer months from 1984 to 2002. Using all proxies and measurements of UV transparency, decadal and longer cycles were apparent but no long-term trend since the first optical measurement in 1896. ?? 2007 Springer Science+Business Media B.V.

  4. Hydrochemical dynamics of the “lake spring” system in the crater of El Chichón volcano (Chiapas, Mexico)

    NASA Astrophysics Data System (ADS)

    Rouwet, D.; Taran, Y.; Inguaggiato, S.; Varley, N.; Santiago Santiago, J. A.

    2008-12-01

    El Chichón volcano (Chiapas, Mexico) erupted violently in March-April 1982, breaching through the former volcano-hydrothermal system. Since then, the 1982 crater has hosted a shallow (1-3.3 m, acidic (pH ˜ 2.2) and warm (˜ 30 °C) crater lake with a strongly varying chemistry (Cl/SO 4 = 0-79 molar ratio). The changes in crater lake chemistry and volume are not systematically related to the seasonal variation of rainfall, but rather to the activity of near-neutral geyser-like springs in the crater (Soap Pool). These Soap Pool springs are the only sources of Cl for the lake. Their geyser-like behaviour with a long-term (months to years) periodicity is due to a specific geometry of the shallow boiling aquifer beneath the lake, which is the remnant of the 1983 Cl-rich (24,000 mg/l) crater lake water. The Soap Pool springs decreased in Cl content over time. The zero-time extrapolation (1982, year of the eruption) approaches the Cl content in the initial crater lake, meanwhile the extrapolation towards the future indicates a zero-Cl content by 2009 ± 1. This particular situation offers the opportunity to calculate mass balance and Cl budget to quantify the lake-spring system in the El Chichón crater. These calculations show that the water balance without the input of SP springs is negative, implying that the lake should disappear during the dry season. The isotopic composition of lake waters (δD and δ 18O) coincide with this crater lake-SP dynamics, reflecting evaporation processes and mixing with SP geyser and meteoric water. Future dome growth, not observed yet in the post-1982 El Chichón crater, may be anticipated by changes in lake chemistry and dynamics.

  5. Seasonal variations in geochemistry of the hyperacidic Ijen Crater Lake, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Sumarti, S.; Sumarti, S.; van Bergen, M. J.; Takano, B.; Sukarnen, S.

    2001-12-01

    Kawah Ijen is a typical crater lake in a tropical climate where there is a balance between the volume of atmospheric precipitation and the level of water in the lake. The crater lake has a regular oval form (600 x 1000 m2), is 180 m deep, and contains about 36 million m3 of turquoise-green colored water (pH ~ 0.2). The water contains extremely high Cl, SO4, F concentrations, the maximum values being about 2,500 mg/kg, 80,000 mg/kg and 1,300 mg/kg respectively. Twenty-four samples of lake water taken during August 1996 (dry season) show most major elements to be homogeneously distributed throughout the lake at this time to a depth of 165 m within a standard deviation of less than 10 %. Homogeneity is most likely due to thorough mixing driven by thermal convection. However, iron and sulphur do not behave in the same way showing variations up to 14 % variation. Monthly monitoring of surface water (1997-2001) shows temporal fluctuations in acidity (pH 0 ~ 0.6) and water level, concentrations of major elements, temperature (20 ~ 45° C). Between 1976-1996, the water level varied by ~ 15 m; and from 1997-2001 by ~ 10 m. The onset of the wet season may coincide with an episodical decrease, a spike, in major element concentrations up to 70 % of their dry season value. This spike occurs annually at the lowest temperature and highest degree of dilution, indicates of the influence of rainfall. However, volcanic gases entering beneath the lake bottom may have added to these temporal changes in the lake especially during phreatic eruptions. Shallow earthquake records do not indicate correlations between seismic activity and chemical changes in the lake. Temporal variations of lake surface temperature show good agreement with major element variations in surface water. Crater lake surface water collected at three points on August 1996, March 2001, May 2001 revealed that the surface water was homogenous in the dry and rainy season within a standard deviation below 7 %. The

  6. Classification and analysis of candidate impact crater-hosted closed-basin lakes on Mars

    NASA Astrophysics Data System (ADS)

    Goudge, Timothy A.; Aureli, Kelsey L.; Head, James W.; Fassett, Caleb I.; Mustard, John F.

    2015-11-01

    We present a new catalog of 205 candidate closed-basin lakes contained within impact craters across the surface of Mars. These basins have an inlet valley that incises the crater rim and flows into the basin but no visible outlet valley, and are considered candidate closed-basin lakes; the presence of a valley flowing into a basin does not necessitate the formation of a standing body of water. The major geomorphic distinction within our catalog of candidate paleolakes is the length of the inlet valley(s), with two major classes - basins with long (>20 km) inlet valleys (30 basins), and basins with short (<20 km) inlet valleys (175 basins). We identify 55 basins that contain sedimentary fan deposits at the mouths of their inlet valleys, of which nine are fed by long inlet valleys and 46 are fed by short inlet valleys. Analysis of the mineralogy of these fan deposits suggests that they are primarily composed of detrital material. Additionally, we find no evidence for widespread evaporite deposit formation within our catalog of candidate closed-basin lakes, which we conclude is indicative of a general transience for any lakes that did form within these basins. Morphometric characteristics for our catalog indicate that as an upper limit, these basins represent a volume of water equivalent to a ∼1.2 m global equivalent layer (GEL) of water spread evenly across the martian surface; this is a small fraction of the modern water ice reservoir on Mars. Our catalog offers a broader context within which results from the Mars Science Laboratory Curiosity rover can be interpreted, as Gale crater is a candidate closed-basin lake contained within our catalog. Gale is also one of 12 closed-basin lakes fed by both long and short inlet valleys, and so in␣situ analyses by Curiosity can shed light on the relative importance of these two types of inlets for any lacustrine activity within the basin.

  7. Distribution and abundance of zooplankton populations in Crater Lake, Oregon

    USGS Publications Warehouse

    Larson, G.L.; McIntire, C.D.; Buktenica, M.W.; Girdner, S.F.; Truitt, R.E.

    2007-01-01

    The zooplankton assemblages in Crater Lake exhibited consistency in species richness and general taxonomic composition, but varied in density and biomass during the period between 1988 and 2000. Collectively, the assemblages included 2 cladoceran taxa and 10 rotifer taxa (excluding rare taxa). Vertical habitat partitioning of the water column to a depth of 200 m was observed for most species with similar food habits and/or feeding mechanisms. No congeneric replacement was observed. The dominant species in the assemblages were variable, switching primarily between periods of dominance of Polyarthra-Keratella cochlearis and Daphnia. The unexpected occurrence and dominance of Asplanchna in 1991 and 1992 resulted in a major change in this typical temporal shift between Polyarthra-K. cochlearis and Daphnia. Following a collapse of the zooplankton biomass in 1993 that was probably caused by predation from Asplanchna, Kellicottia dominated the zooplankton assemblage biomass between 1994 and 1997. The decline in biomass of Kellicottia by 1998 coincided with a dramatic increase in Daphnia biomass. When Daphnia biomass declined by 2000, Keratella biomass increased again. Thus, by 1998 the assemblage returned to the typical shift between Keratella-Polyarthra and Daphnia. Although these observations provided considerable insight about the interannual variability of the zooplankton assemblages in Crater Lake, little was discovered about mechanisms behind the variability. When abundant, kokanee salmon may have played an important role in the disappearance of Daphnia in 1990 and 2000 either through predation, inducing diapause, or both. ?? 2007 Springer Science+Business Media B.V.

  8. Long-term limnological research and monitoring at Crater Lake, Oregon

    USGS Publications Warehouse

    Larson, G.L.; Collier, R.; Buktenica, M.

    2007-01-01

    Crater Lake is located in the caldera of Mount Mazama in Crater Lake National Park, Oregon. The lake has a surface area of about 53 km2at an elevation of 1882 m and a maximum depth of 594 m. Limited studies of this ultraoligotrophic lake conducted between 1896 and 1981, lead to a 10-year limnological study to evaluate any potential degradation of water quality. No long-term variations in water quality were observed that could be attributed to anthropogenic activity. Building on the success of this study, a permanent limnological program has been established with a long-term monitoring program to insure a reliable data base for use in the future. Of equal importance, this program serves as a research platform to develop and communicate to the public a better understanding of the coupled biological, physical, and geochemical processes in the lake and its surrounding environment. This special volume represents our current state of knowledge of the status of this pristine ecosystem including its special optical properties, algal nutrient limitations, pelagic bacteria, and models of the inter-relationships of thermal properties, nutrients, phytoplankton, deep-water mixing, and water budgets. ?? 2007 Springer Science+Business Media B.V.

  9. Time Scale of Magma Mixing Determined From Olivine Speedometry at Williams Crater, Crater Lake, OR

    NASA Astrophysics Data System (ADS)

    Adams, D. T.; Tepley, F. J.; Bacon, C. R.

    2006-12-01

    Magma mixing is postulated to be a common and important petrogenetic process at many arc volcanoes which not only may mechanically mix liquids and crystals from disparate magmas but also may trigger eruptions arresting these mixing processes. During such mixing, crystals in equilibrium with their respective magmas may exchange between the different magma types, and re-equilibrate with the newly formed hybrid magma. In many cases, the attempt by these mixed crystals at re-equilibration takes the form of major and trace element diffusion profiles which can then be exploited for geochronometric information. One postulated location that illustrates these processes is the Williams Crater complex, Crater Lake, Oregon. This cinder cone just outside the western rim of the Crater Lake caldera is composed of mingled basalt, andesite, and dacite formed by mixing of basaltic andesite magma, dacite magma, and gabbro (Bacon, 1990). Olivine crystals from this complex are found both within microxenoliths, and completely disaggregated from their xenolithic hosts and in contact with the silicic melt. In order to determine the time frame profiles we used the methodology of Costa and Chakraborty (2004) and Costa and Dungan (2005) for anisotropic diffusion of Fe, Mg, Mn, and Ni in olivine. Analyses were performed with an electron microprobe (WDS) and crystallographic orientations were determined using electron backscatter diffraction (EBSD). WDS traverses were taken from rim-to-rim through the center of the crystal, parallel to sub-parallel to a crystallographic axis in 4 μm steps. Previous experimental studies have shown cation diffusion is fastest along the c-crystallographic axis and slower along the a- and b-axes, and diffusion is strongly dependant on fo2 and temperature. When possible, two traverses were performed perpendicular to one another. Preliminary results show that in cases where the xenolithic olivine is in contact with the melt, compositional diffusion profiles are

  10. High spatio-temporal resolution observations of crater lake temperatures at Kawah Ijen volcano, East Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Lewicki, Jennifer L.; Caudron, Corentin; van Hinsberg, Vincent J.; Hilley, George E.

    2016-08-01

    The crater lake of Kawah Ijen volcano, East Java, Indonesia, has displayed large and rapid changes in temperature at point locations during periods of unrest, but measurement techniques employed to date have not resolved how the lake's thermal regime has evolved over both space and time. We applied a novel approach for mapping and monitoring variations in crater lake apparent surface ("skin") temperatures at high spatial (˜32 cm) and temporal (every 2 min) resolution at Kawah Ijen on 18 September 2014. We used a ground-based FLIR T650sc camera with digital and thermal infrared (TIR) sensors from the crater rim to collect (1) a set of visible imagery around the crater during the daytime and (2) a time series of co-located visible and TIR imagery at one location from pre-dawn to daytime. We processed daytime visible imagery with the Structure-from-Motion photogrammetric method to create a digital elevation model onto which the time series of TIR imagery was orthorectified and georeferenced. Lake apparent skin temperatures typically ranged from ˜21 to 33 °C. At two locations, apparent skin temperatures were ˜4 and 7 °C less than in situ lake temperature measurements at 1.5 and 5-m depth, respectively. These differences, as well as the large spatio-temporal variations observed in skin temperatures, were likely largely associated with atmospheric effects such as the evaporative cooling of the lake surface and infrared absorption by water vapor and SO2. Calculations based on orthorectified TIR imagery thus yielded underestimates of volcanic heat fluxes into the lake, whereas volcanic heat fluxes estimated based on in situ temperature measurements (68 to 111 MW) were likely more representative of Kawah Ijen in a quiescent state. The ground-based imaging technique should provide a valuable tool to continuously monitor crater lake temperatures and contribute insight into the spatio-temporal evolution of these temperatures associated with volcanic activity.

  11. Comparative physiographic diagrams of Mount St. Helens, Washington, and Crater Lake, Oregon

    USGS Publications Warehouse

    Alpha, Tau Rho; Morley, Jim M.

    1983-01-01

    These physiographic diagrams provide a visual comparison of two Cascade Range volcanoes which have had their tops destroyed in different ways -- Mount St. Helens in 1980, Mount Mazama (whose site is now occupied by Crater Lake) about 6,800 years ago. Both volcanoes are viewed from the north from 30 degrees above the horizon, with no vertical exaggeration. The ground area portrayed in each diagram is equal; the south edge of the Mount St. Helens drawing is lower than that of Crater Lake drawing because elevations drop away toward the south, whereas elevations are more constant at the north and south edges of the Crater Lake diagram. 

  12. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars

    USGS Publications Warehouse

    Grotzinger, J.P.; Gupta, S.; Malin, M.C.; Rubin, D.M.; Schieber, J.; Siebach, K.; Sumner, D.Y.; Stack, K.M.; Vasavada, A.R.; Arvidson, R.E.; Calef, F.; Edgar, Lauren; Fischer, W.F.; Grant, J.A.; Griffes, J.L.; Kah, L.C.; Lamb, M.P.; Lewis, K.W.; Mangold, N.; Minitti, M.E.; Palucis, M.C.; Rice, M.; Williams, R.M.E.; Yingst, R.A.; Blake, D.; Blaney, D.; Conrad, P.; Crisp, J.A.; Dietrich, W.E.; Dromart, G.; Edgett, K.S.; Ewing, R.C.; Gellert, R.; Hurowitz, J.A.; Kocurek, G.; Mahaffy, P.G.; McBride, M.J.; McLennan, S.M.; Mischna, M.A.; Ming, D.; Milliken, R.E.; Newsom, H.; Oehler, D.; Parker, T.J.; Vaniman, D.; Wiens, R.C.; Wilson, S.A.

    2015-01-01

    The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

  13. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars.

    PubMed

    Grotzinger, J P; Gupta, S; Malin, M C; Rubin, D M; Schieber, J; Siebach, K; Sumner, D Y; Stack, K M; Vasavada, A R; Arvidson, R E; Calef, F; Edgar, L; Fischer, W F; Grant, J A; Griffes, J; Kah, L C; Lamb, M P; Lewis, K W; Mangold, N; Minitti, M E; Palucis, M; Rice, M; Williams, R M E; Yingst, R A; Blake, D; Blaney, D; Conrad, P; Crisp, J; Dietrich, W E; Dromart, G; Edgett, K S; Ewing, R C; Gellert, R; Hurowitz, J A; Kocurek, G; Mahaffy, P; McBride, M J; McLennan, S M; Mischna, M; Ming, D; Milliken, R; Newsom, H; Oehler, D; Parker, T J; Vaniman, D; Wiens, R C; Wilson, S A

    2015-10-01

    The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp). PMID:26450214

  14. Convective heat discharge of Wood River group of springs in the vicinity of Crater Lake, Oregon

    USGS Publications Warehouse

    Nathenson, Manuel; Mariner, Robert H.; Thompson, J. Michael

    1994-01-01

    Data sets for spring and stream chemistry are combined to estimate convective heat discharge and discharge anomalous amounts of sodium and chloride for the Wood River group of springs south of Crater Lake. The best estimate of heat discharge is 87 MWt based on chloride inventory; this value is 3-5 times the heat input to Crater Lake itself. Anomalous discharges of sodium and chloride are also larger that into Crater Lake. Difference between the chemical and thermal characteristics of the discharge into Crater Lake and those from the Wood River group of springs suggest that the heat sources for the two systems may be different, although both ultimately related to the volcanic system.

  15. The origin of a large (> 3 km) maar volcano by coalescence of multiple shallow craters: Lake Purrumbete maar, southeastern Australia

    NASA Astrophysics Data System (ADS)

    Jordan, S. C.; Cas, R. A. F.; Hayman, P. C.

    2013-03-01

    Lake Purrumbete maar is located in the intraplate, monogenetic Newer Volcanics Province in southeastern Australia. The extremely large crater of 3000 m in diameter formed on an intersection of two fault lines and comprises at least three coalesced vents. The evolution of these vents is controlled by the interaction of the tectonic setting and the properties of both hard and soft rock aquifers. Lithics in the maar deposits originate from country rock formations less than 300 m deep, indicating that the large size of the crater cannot only be the result of the downwards migration of the explosion foci in a single vent. Vertical crater walls and primary inward dipping beds evidence that the original size of the crater has been largely preserved. Detailed mapping of the facies distributions, the direction of transport of base surges and pyroclastic flows, and the distribution of ballistic block fields, form the basis for the reconstruction of the complex eruption history,which is characterised by alternations of the eruption style between relatively dry and wet phreatomagmatic conditions, and migration of the vent location along tectonic structures. Three temporally separated eruption phases are recognised, each starting at the same crater located directly at the intersection of two local fault lines. Activity then moved quickly to different locations. A significant volcanic hiatus between two of the three phases shows that the magmatic system was reactivated. The enlargement of especially the main crater by both lateral and vertical growth led to the interception of the individual craters and the formation of the large circular crater. Lake Purrumbete maar is an excellent example of how complicated the evolution of large, seemingly simple, circular maar volcanoes can be, and raises the question if these systems are actually monogenetic.

  16. Gas flushing through hyper-acidic crater lakes: the next steps within a reframed monitoring time window

    NASA Astrophysics Data System (ADS)

    Rouwet, Dmitri

    2016-04-01

    Tracking variations in the chemical composition, water temperature and pH of brines from peak-activity crater lakes is the most obvious way to forecast phreatic activity. Volcano monitoring intrinsically implies a time window of observation that should be synchronised with the kinetics of magmatic processes, such as degassing and magma intrusion. To decipher "how much time ago" a variation in degassing regime actually occurred before eventually being detected in a crater lake is key, and depends on the lake water residence time. The above reasoning assumes that gas is preserved as anions in the lake water (SO4, Cl, F anions), in other words, that scrubbing of acid gases is complete and irreversible. Less is true. Recent work has confirmed, by direct MultiGas measurement from evaporative plumes, that even the strongest acid in liquid medium (i.e. SO2) degasses from hyper-acidic crater lakes. The less strong acid HCl has long been recognised as being more volatile than hydrophyle in extremely acidic solutions (pH near 0), through a long-term steady increase in SO4/Cl ratios in the vigorously evaporating crater lake of Poás volcano. We now know that acidic gases flush through hyper-acidic crater lake brines, but we don't know to which extend (completely or partially?), and with which speed. The chemical composition hence only reflects a transient phase of the gas flushing through the lake. In terms of volcanic surveillance this brings the advantage that the monitoring time window is definitely shorter than defined by the water chemistry, but yet, we do not know how much shorter. Empirical experiments by Capaccioni et al. (in press) have tried to tackle this kinetic problem for HCl degassing from a "lab-lake" on the short-term (2 days). With this state of the art in mind, two new monitoring strategies can be proposed to seek for precursory signals of phreatic eruptions from crater lakes: (1) Tracking variations in gas compositions, fluxes and ratios between species in

  17. Paenibacillus baekrokdamisoli sp. nov., isolated from soil of crater lake.

    PubMed

    Lee, Keun Chul; Kim, Kwang Kyu; Kim, Jong-Shik; Kim, Dae-Shin; Ko, Suk-Hyung; Yang, Seung-Hoon; Lee, Jung-Sook

    2016-05-01

    A novel bacterial strain, Back-11T, was isolated from sediment soil of a crater lake, Baekrokdam, Hallasan, Jeju, Republic of Korea. Cells of strain Back-11T were Gram-stain-positive, motile, endospore-forming, rod-shaped and oxidase- and catalase-positive. It contained anteiso-C15 : 0 as the major fatty acid, menaquinone-7 (MK-7) as the predominant isoprenoid quinone, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and four unidentified aminophospholipids as the main polar lipids, and meso-diaminopimelic acid as the diagnostic diamino acid in the cell-wall peptidoglycan. The DNA G+C content was 45.3 mol%. Phylogenetic analysis, based on 16S rRNA gene sequencing, showed that strain Back-11T was most closely related to Paenibacillus taihuensis THMBG22T (95.5 % similarity) and fell into a clade in the genus Paenibacillus. On the basis of phylogenetic, chemotaxonomic and phenotypic data, strain Back-11T represents a novel species in the genus Paenibacillus, for which the name Paenibacillus baekrokdamisoli sp. nov. is proposed. The type strain is Back-11T ( = KCTC 33723T = CECT 8890T). PMID:26868819

  18. The boron isotopic composition of geothermal waters and crater lakes from Java, Indonesia

    NASA Astrophysics Data System (ADS)

    Purnomo, B. J.; Pichler, T.; You, C. F.

    2014-12-01

    The presences of two different types of geothermal systems, volcanic-hosted and fault-hosted, and two different types of acid crater lakes, acid sulfate and acid chloride, on Java, Indonesia presented the opportunity to investigate boron isotope systematic in such contrasting systems. Fault-hosted hot springs and the acid chloride crater lakes had light δ11B (-2.4 to +0.49 ‰), similar to geothermal brines. Meanwhile, the δ11B values of volcanic-hosted hot springs ranged from -0.7 to +12.8 ‰ and acid-sulfate crater lakes ranged from +5.5 to +34.8 ‰, which were heavier than the geothermal vapor phase (δ11B= +3.8 ‰). The absence of magmatic gases and the fast ascent of the fault-hosted thermal waters inhibited B isotope fractionation, thus their original light δ11B signature from the reservoir was maintained. In contrast, in volcanic-hosted geothermal systems magmatic degassing produced a more reactive geothermal water, which combined with the relatively longer ascent produced heavy δ11B signatures. The light δ11B signature of acid chloride crater lakes was produced by rock dissolution, also indicated by its B/Cl ratios, which were similar to those of andesitic rocks. The continuous H2S, SO2 and HCl gases supply favors rock dissolution in the acid chloride crater lakes and thus little to no B isotope fractionation was observed. In contrast, condensation of the geothermal vapor phase combined with evaporation and B adsorption onto clay minerals caused a δ11B enrichment in the acid sulfate crater lakes. The very heavy δ11B value of +34.8 ‰ in the acid sulfate crater lake of Kawah Sikidang likely involved some reaction with sedimentary rocks in the subsurface.

  19. El Chichón crater lake dynamic based on continuous physical data and mass-heat budget

    NASA Astrophysics Data System (ADS)

    Peiffer, L.; Taran, Y.

    2011-12-01

    The March-April 1982 Plinian eruption of El Chichón volcano destroyed the summit domes system and created a new 200 m deep crater. Since then, a shallow lake (~3 m) with acidic pH (~2.3), and temperature around 30°C appeared in the crater. This lake has never disappeared until now although its volume has suffered important variations from 40,000 m3 to 160,000 m3. Chemical composition of the lake is also highly variable (Cl/SO4 = 0-79 molar ratio), alternating between acid-sulfate and acid-chloride-sulfate composition. These variations can occur very fast within few weeks and are not directly correlated with precipitation. Due to its shallow depth and small volume, El Chichón crater lake is probably one of the most dynamic crater lake on earth. These rapid changes in chemistry and volume reflect the dynamic of one group of geyser-type springs ('Soap Pools springs, SP') located offshore and the input of hydrothermal steam underneath the crater. The SP springs discharge sporadically to the lake neutral waters with Cl content currently around 3000 mg/l, while the condensed steam feeds the lake with Cl-free and SO4-rich acid water. In this study, we present for the first time continuous physical data of the crater lake (temperature, depth, meteoric precipitation, wind velocity, solar radiation, air humidity). These data were registered by a meteorological station and two dataloggers installed inside and outside the lake. Using a mass and heat budget model constrained with these data, we were able to estimate the flux of 'hydrothermal' fluid entering the lake through the sub-lacustrian fumaroles and SP springs. Tracing the variations of the input flux in time can be help to understand the dynamic of the 'crater lake-SP springs-fumaroles' system but also can provide an efficient way of monitoring the volcanic activity. During the observation period, the mean mass flux entering the lake (Min) was respectively of 12 ± 2 kg/s, corresponding to a total heat flux (Ein) of

  20. CO2 emission from lake-filled Katanuma crater, Narugo volcano, Japan

    NASA Astrophysics Data System (ADS)

    Padron, E.; Hernandez Perez, P. A.; Mori, T.; Perez, N.

    2010-12-01

    Narugo volcano is composed by four dacitic Holocene age lava domes surrounding the 400 m wide lake-filled Katanuma crater. A large caldera, 5.5 x 7 km NW of the city of Sendai was formed by paroxysmal eruptions 45 ka ago and after this activity, lava flows and lava domes were formed in the inner part of the caldera. The only known eruption at Narugo in historical time occurred in 837 AD. Katanuma is known as one of the most acidic lakes in the world and boiling springs, water vapour and volcanic gases are discharged from the lake botton. As a result of this degassing, a relatively intense volcanic gas emission is observed along the lake surface in the form of gas bubbles. To compute the total CO2 degassing rate through Katanuma water lake surface, a CO2 emission survey was carried out on August 2010. CO2 efflux measurements were performed on the water surface by means of a portable NDIR sensor at 86 sampling sites, following a modified floating device of the accumulation chamber method.CO2 efflux values ranged between 16 and 14300 g m-2 d-1. CO2 efflux map was constructed using sequential Gaussian simulation. An important CO2 degassing structure was observed at the water surface, located on its west half part, with a N-S trending. An averaged map of 200 equiprobable simulations allowed us to compute 35.2 ± 4.1 t/d of CO2 released to the atmosphere through the water surface on a area of 0.14 km2. These results suggest clearly that monitoring CO2 emission rate from lake-filled Katanuma crater will contribute to improve the Narugo volcano surveillance program as well as our knowledge on the global CO2 emission from volcanic lakes, which is actually estimated about 136 Mt year-1 (Pérez et al., 2010). Reference: Pérez et al., 2010. CVL 7 Workshop Costa Rica, March 2010.

  1. Controls on lava lake level at Halema`uma`u Crater, Kilauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, M. R.; Orr, T. R.

    2013-12-01

    Lava level is a fundamental measure of lava lake activity, but very little continuous long-term data exist worldwide to explore this aspect of lava lake behavior. The ongoing summit eruption at Kilauea Volcano began in 2008 and is characterized by an active lava lake within the eruptive vent. Lava level has been measured nearly continuously at Kilauea for several years using a combination of webcam images, laser rangefinder, and terrestrial LIDAR. Fluctuations in lava level have been a common aspect of the eruption and occur over several timescales. At the shortest timescale, the lava lake level can change over seconds to hours owing to two observed shallow gas-related processes. First, gas pistoning is common and is driven by episodic gas accumulation and release from the surface of the lava lake, causing the lava level to rise and fall by up to 20 m. Second, rockfalls into the lake trigger abrupt gas release, and lava level may drop as much as 10 m as a result. Over days, cyclic changes in lava level closely track cycles of deflation-inflation (DI) deformation events at the summit, leading to level changes up to 50 m. Rift zone intrusions have caused large (up to 140 m) drops in lava level over several days. On the timescale of weeks to months, the lava level follows the long-term inflation and deflation of the summit region, resulting in level changes up to 140 m. The remarkable correlation between lava level and deflation-inflation cycles, as well as the long-term deformation of the summit region, indicates that the lava lake acts as a reliable 'piezometer' (a measure of liquid pressure in the magma plumbing system); therefore, assessments of summit pressurization (and rift zone eruption potential) can now be carried out with the naked eye. The summit lava lake level is closely mirrored by the lava level within Pu`u `O`o crater, the vent area for the 30-year-long eruption on Kilauea's east rift zone, which is 20 km downrift of the summit. The coupling of these

  2. Geophysical Signature of the Lake Bosumtwi Impact Crater from Pre-drilling Site Surveys

    NASA Astrophysics Data System (ADS)

    Banour, S.; Pohl, J.; Menyeh, A.; Milkereit, B.; Boadu, F.

    2006-12-01

    The Bosumtwi impact crater located near Kumasi, Ghana was formed by a meteorite impact about one million years ago and has a diameter of about 10.5 km. Geophysical investigations involving gravity and magnetic measurements were carried out at the Bosumtwi crater to determine the geophysical signature of the crater with the aim of understanding the impact process. Gravity data was acquired on land at 163 locations around the crater area, as well as on the shore of the lake. The separation between the gravity stations was 500 m for profiles which ran radially toward the lake, and 700 1000 m along roads and footpaths which ran parallel to the shore. In addition, marine gravity and magnetic surveys were carried out along 14 north-south and 15 east- west profiles on the lake with a line spacing of 800 m using a Garmin 235 Echo Sounder/GPS as a navigational tool. Results from gravity modelling showed that the gravity signature of the crater is characterized by a negative Bouguer anomaly with an amplitude roughly equal to 18 mgal. The results also indicated a central uplift at 250 m depth below the lake, thus confirming it as a complex impact crater. Magnetic modelling yielded a model for the causative body, which is located north of the central uplift. The model has a magnetic susceptibility of 0.03 SI and extends from 200 to 610 m depth below the lake surface. The causative body has been interpreted as magnetized bodies consisting of thin sheets of suevitic impact formations. These results serve as a contribution to the understanding of the impact process of this young crater.

  3. High spatio-temporal resolution observations of crater-lake temperatures at Kawah Ijen volcano, East Java, Indonesia

    USGS Publications Warehouse

    Lewicki, Jennifer L.; Corentin Caudron; Vincent van Hinsberg; George Hilley

    2016-01-01

    The crater lake of Kawah Ijen volcano, East Java, Indonesia, has displayed large and rapid changes in temperature at point locations during periods of unrest, but measurement techniques employed to-date have not resolved how the lake’s thermal regime has evolved over both space and time. We applied a novel approach for mapping and monitoring variations in crater-lake apparent surface (“skin”) temperatures at high spatial (~32 cm) and temporal (every two minutes) resolution at Kawah Ijen on 18 September 2014. We used a ground-based FLIR T650sc camera with digital and thermal infrared (TIR) sensors from the crater rim to collect (1) a set of visible imagery around the crater during the daytime and (2) a time series of co-located visible and TIR imagery at one location from pre-dawn to daytime. We processed daytime visible imagery with the Structure-from-Motion photogrammetric method to create a digital elevation model onto which the time series of TIR imagery was orthorectified and georeferenced. Lake apparent skin temperatures typically ranged from ~21 to 33oC. At two locations, apparent skin temperatures were ~ 4 and 7 oC less than in-situ lake temperature measurements at 1.5 and 5 m depth, respectively. These differences, as well as the large spatio-temporal variations observed in skin temperatures, were likely largely associated with atmospheric effects such as evaporative cooling of the lake surface and infrared absorption by water vapor and SO2. Calculations based on orthorectified TIR imagery thus yielded underestimates of volcanic heat fluxes into the lake, whereas volcanic heat fluxes estimated based on in-situ temperature measurements (68 to 111 MW) were likely more representative of Kawah Ijen in a quiescent state. The ground-based imaging technique should provide a valuable tool to continuously monitor crater-lake temperatures and contribute insight into the spatio-temporal evolution of these temperatures associated with volcanic activity.

  4. Shifts in morphology and diet of non-native sticklebacks introduced into Japanese crater lakes

    PubMed Central

    Adachi, Tatsuya; Ishikawa, Asano; Mori, Seiichi; Makino, Wataru; Kume, Manabu; Kawata, Masakado; Kitano, Jun

    2012-01-01

    An increasing number of exotic animals are causing ecological problems. Therefore, for better ecosystem management, it is important to understand how exotic species colonize and adapt to novel environments. The threespine sticklebacks (Gasterosteus aculeatus) can be a good vertebrate model system to explore the ecological and genetic mechanisms of adaptation not only in natural populations, but also in non-native populations. Although morphological changes have been documented in several introduced populations of stickleback, little is known about the dietary changes during colonization into novel environments. Here, we investigated the morphological and dietary changes of exotic threespine stickleback populations introduced into three Japanese crater lakes (Lake Towada, Lake Kussharo, and Lake Shikotsu). Sticklebacks were introduced into the crater lakes likely along with salmonids transplanted for aquaculture. The stickleback population in Lake Kussharo had multiple mitochondrial haplotypes and had larger phenotypic variances than other crater lake stickleback populations that had only one mitochondrial haplotype. Compilation of historical data on the morphology and stomach contents of the Lake Towada stickleback population showed that substantial shifts in body size and stomach contents occurred after colonization. Some of these changes may be related to an outbreak of the Schistocephalus parasite. These results suggest that sticklebacks can change their morphology and trophic ecology when they colonize novel environments. Therefore, extreme care should be taken when salmonids are transported between watersheds for aquaculture and that long-term monitoring of exotic species is essential for ecosystem management. In addition, further genetic studies on phenotypic changes in crater lake sticklebacks would help elucidate the genetic mechanisms underlying the adaptation of exotic fishes to novel environments. PMID:22833786

  5. Analysis of the Paleoenvironment of Gale Crater on Mars: Using Ephemeral Lakes in Western Australia as Analogs to the Mineral Assemblages of Gale Crater

    NASA Astrophysics Data System (ADS)

    Cocks, C.; Baldridge, A. M.; Thomson, B. J.

    2014-12-01

    Aluminum and Fe/Mg-phyllosilicates, as well as sulfates, are abundant in the layered sediments of the central mound of Gale Crater on Mars. Each of these mineral types are useful indicators of depositional conditions regarding pH, where Fe/Mg-phyllosilicates form in higher pH waters, while Al-phyllosilicates and sulfates form in more acidic waters. A general succession from higher pH aquatic environments to lower pH environments is evident during the Noachian and early Hesperian (3.6~3.8 Ga). However, substantial interbedding of these mineral groups is also observed at Gale, indicating pH boundaries that existed contemporaneously at the time of deposition. This is consistent with mineral distributions that are observed in ephemeral lakes on Earth, making them useful as analogs to the geochemistry of Gale Crater. This study will analyze the surficial mineral depositional patterns at Lake Gilmore, WA, to better understand how pH gradients are represented in contemporaneous sediment deposits. This will be performed by identifying minerals based on their unique reflectance signatures in the visible to near-infrared range (0.5-2.5 mm). Reflectance data collected by the HyMap™ hyperspectral scanner will be analyzed using the ENVI software to map the predominant minerals present on the lakebed surface. We expect to see minerals associated with a pH gradient that is related to lake depth, with Fe and alkali earth phyllosilicates representing deeper, less acidic waters, and aluminous phyllosilicates and sulfates representing near surface waters that are more acidic. This is potentially due to the circulation of upwelling groundwaters, or the change in chemistry may have arisen due to microbial activity, an intriguing possibility that would have significant implications for evidence of past microbial life on the Martian surface and would provide a more detailed picture of the paleoenvironment at Gale Crater.

  6. Hydrothermal circulation at the world's highest lake? An environmental study of the Licancabur Volcano crater lake as a terrestrial analog to martian paleolakes.

    NASA Astrophysics Data System (ADS)

    Hock, A. N.; Cabrol, N. A.; Grin, E. A.; Fike, D. A.; Paige, D. A.; 2002 Licancabur Expedition Team

    2003-04-01

    At approximately 6000 meters above sea level, the crater of Licancabur Volcano (22 50'S, 67 53'W) houses the highest lake in the world, yet remains largely unexplored. In particular, the physical environment of the lake--particularly its stability and any remaining geothermal activity--is not well understood. Using a model for the temperature of maximum density for freshwater as a function of pressure (Eklund), we calculated that the bottom water temperature of the summit lake should be approximately 4 C. However, Leach et al. measured the water temperature at depth to be 6 C. This discrepancy, as well as the observation that the lake remains liquid for much of the year despite sub freezing air temperatures, suggests that there may be a heat source supporting the lake's temperature and biological community. We present the results of two studies here: the goal of this work is to understand the role of geothermal fluid input to the summit lake in terms of energy balance, the physical constraints on endemic biology, and the analogy to ancient martian hydrothermal systems (e.g. volcanic lakes, crater lakes, hot springs, etc.). First, we present physical data from the lake in a new model of energy balance. In situ measurements of pH, temperature, and total dissolved solids suggest that the Licancabur summit lake is a ¨low-activity¨ (as per Pasternack and Varekamp) lake with a diffuse geothermal fluid input. Secondly, mass spectrometry and ion chromatography were used to study water samples taken from the summit lake, as well as two local lagunas and several geothermal springs at the base of the volcano. The case for a hydrothermal system in the summit lake is further strengthened here by preliminary ion chromatography results, which show elevated concentrations of sulfate and chloride with respect to local meteoric waters. Understanding the relationship between the physical environment and biotic community remains the mainstay for future work on this project in an

  7. Bathymetry, heat output and convection in Ruapehu Crater Lake, New Zealand

    NASA Astrophysics Data System (ADS)

    Hurst, A. W.; Dibble, R. R.

    1981-02-01

    Bathymetric observations of Ruapehu Crater Lake show that it became shallower and its volume decreased by 3 × 10 6 m 3 between 1965 and 1970. It is likely that this was due to lava moving upwards in the region under the lake. From the regular measurements of Crater Lake temperature, outflow, and chloride and magnesium ion concentrations, the inflows of steam, cold water and chloride and magnesium ions were calculated, using the 1970 volume. Only about half the precipitation falling on and around the lake mixes with the lake water, since the cold fresh water floats on top of the denser lake water, and travels to the outlet without mixing with the main body of water in the lake. The chloride content of the input steam appears to vary with time, in a similar fashion to that of White Island fumaroles. Temperature and density profiles of the lake in 1965 and 1966 indicated that convection was occurring. The temperature profile of the top 175 m of the lake agreed with a model of turbulent convection in small cells, giving a temperature gradient at any level in the lake proportional to the heat flux at that level. The convection model predicted that the temperature at depth would exceed the local boiling point if the thermal power input reached a value which would sustain a surface temperature approaching 60°C. This prediction of instability was not inconsistent with observations. Convection in the present Crater Lake probably occurs in the form of thermal plumes from small sources.

  8. Snettisham Hydroelectric Project, Alaska second stage development, Crater lake. Final foundation report. Final report

    SciTech Connect

    Not Available

    1992-09-04

    The important geologic features and methods used to construct the Crater Lake stage of the Snettisham Hydroelectric project, built between 1985 and 1989, are discussed. The project added 31 megawatts of non-polluting, renewable electric power for Juneau, Alaska and the surrounding area. Features of the report include the power tunnel and access adits, penstock excavation, surge shaft, gate shaft and lake top. Construction aspects include the general geology, design features, construction methods, geologic conditions encountered, ground support requirements, grouting, instrumentation and tunnel filling. Foundation conditions for the Crater Lake status were excellent, permitting the power and penstock tunnel and shafts to be constructed essentially unlined. The basic rock type throughout the project is a high-quality, quartz diorite gneiss with randomly spaced, subparallel basalt dikes.... Unlined rock tunnels, Power tunnel, Penstocks, Lake tap, Surge shaft.

  9. Temporal evolution of micro-eruptions within the crater lake of White Island (Whakaari) during January/February 2013

    NASA Astrophysics Data System (ADS)

    Edwards, Matt; Kennedy, Ben; Jolly, Art; Scheu, Bettina; Taddeucci, Jacopo; Jousset, Philippe; Schmid, Di

    2015-04-01

    Micro-eruptions are potentially modulated by hydrothermal systems and crater lakes but to date have not been well studied. In January/February 2013 White Island (Whakaari), New Zealand, experienced an about three week long period of atypical, frequent micro-eruptions within its crater lake. Many of these micro-eruptions were recorded by tour operators and GNS personnel monitoring the lake activity. Analysis of this video footage reveals an increasingly energetic eruption style. Deformation of the muddy lake surface by ascending bubbles begins as irregularly shaped bursts, producing liquid strings of mud ejected to heights of less than 10m at 10-15m/s. As the episode progresses, eruption frequency is maintained at semi-regular <10s intervals. Each eruption however starts with an increasingly hemispheric surface deformation ~6m in diameter, and bursts occur as "star-bursts" with ejection of less fluidal ash/mud clots. In addition, these bursts are commonly followed within 2s by a more vertical and energetic secondary ejection of material, which occasionally ejects through the deformed hemispheric surface up to >100m high, and reaches ejection velocities up to 45m/s. The period of frequent "star-bursts" is then followed by a two day phase of constant ~30-75m high ash ejection resulting in the formation of a tuff cone with a central open conduit of 6m within the former crater lake. We theorise that this behaviour is influenced by evolving bubble overpressure/volume, including the presence or absence of a trailing wake of smaller bubbles and is modulated over the eruption episode by the viscosity of the crater lake. In the early stages of the episode a lower viscosity lake provides little resistance to rising gas/ash mixtures. Bubble coalescence and/or overpressure development is therefore minimised, resulting in low energy bursts. Over the course of this episode the viscosity of the lake increases due to addition of ash from ash-carrying gas flux and fluid loss by

  10. Slope activity in Gale crater, Mars

    USGS Publications Warehouse

    Dundas, Colin M.; McEwen, Alfred S.

    2015-01-01

    High-resolution repeat imaging of Aeolis Mons, the central mound in Gale crater, reveals active slope processes within tens of kilometers of the Curiosity rover. At one location near the base of northeastern Aeolis Mons, dozens of transient narrow lineae were observed, resembling features (Recurring Slope Lineae) that are potentially due to liquid water. However, the lineae faded and have not recurred in subsequent Mars years. Other small-scale slope activity is common, but has different spatial and temporal characteristics. We have not identified confirmed RSL, which Rummel et al. (Rummel, J.D. et al. [2014]. Astrobiology 14, 887–968) recommended be treated as potential special regions for planetary protection. Repeat images acquired as Curiosity approaches the base of Aeolis Mons could detect changes due to active slope processes, which could enable the rover to examine recently exposed material.

  11. Sequence and relative timing of large lakes in Gale crater (Mars) after the formation of Mount Sharp

    NASA Astrophysics Data System (ADS)

    Palucis, Marisa C.; Dietrich, William E.; Williams, Rebecca M. E.; Hayes, Alexander G.; Parker, Tim; Sumner, Dawn Y.; Mangold, Nicolas; Lewis, Kevin; Newsom, Horton

    2016-03-01

    The quantification of lake levels in Gale crater is important to define the hydrologic and climatic history experienced by the sedimentary deposits found by Curiosity. We propose that there were at least three major lake stands within Gale, each persisted >1000 years, and all occurred after Mount Sharp reached close to its current topographic form. Deltaic deposits off the southern rim of Gale, derived from incision of Farah Vallis, and corresponding deposits off the southern flank of Mount Sharp define the highest lake level, which had a mean depth of 700 m. Canyons similar in form to Farah Vallis enter into craters and/or the crustal dichotomy near Gale from the south, suggesting that the highest lake was supplied by a large-scale flow system. The next lake level, established after a period of drying and rewetting, is defined by four deltaic features, three sourced from Mount Sharp and one from the western rim of Gale, as well as the termination of gullies around the northern rim of Gale. This second lake level had a mean depth of 300 m. The presence of the gullies suggests more locally sourced water. Lake levels then rose another 100 m, as evidenced by two deltaic deposits derived from the rim of Gale and the termination of a second set of gullies. Post-lake, reduced hydrologic activity continued, evidenced by a time of fan building (including Peace Vallis). The sequence of events suggests an episodic shift through time from relatively wet regional conditions to a drier environment with local runoff.

  12. Phylogeography, colonization and population history of the Midas cichlid species complex (Amphilophus spp.) in the Nicaraguan crater lakes

    PubMed Central

    2010-01-01

    Background Elucidation of the mechanisms driving speciation requires detailed knowledge about the phylogenetic relationships and phylogeography of the incipient species within their entire ranges as well as their colonization history. The Midas cichlid species complex Amphilophus spp. has been proven to be a powerful model system for the study of ecological specialization, sexual selection and the mechanisms of sympatric speciation. Here we present a comprehensive and integrative phylogeographic analysis of the complete Midas Cichlid species complex in Nicaragua (> 2000 individuals) covering the entire distributional range, using two types of molecular markers (the mitochondrial DNA control region and 15 microsatellites). We investigated the majority of known lake populations of this species complex and reconstructed their colonization history in order to distinguish between alternative speciation scenarios. Results We found that the large lakes contain older and more diverse Midas Cichlid populations, while all crater lakes hold younger and genetically less variable species assemblages. The large lakes appear to have repeatedly acted as source populations for all crater lakes, and our data indicate that faunal exchange among crater lakes is extremely unlikely. Despite their very recent (often only a few thousand years old) and common origin from the two large Nicaraguan lakes, all crater lake Midas Cichlid radiations underwent independent, but parallel, evolution, and comprise distinct genetic units. Indeed several of these crater lakes contain multiple genetically distinct incipient species that most likely arose through sympatric speciation. Several crater lake radiations can be traced back to a single ancestral line, but some appear to have more than one founding lineage. The timing of the colonization(s) of each crater lake differs, although most of them occurred more (probably much more) recently than 20,000 years ago. Conclusion The genetic differentiation

  13. New Evidence Supporting an Ice-covered Lake in Gusev Crater

    NASA Technical Reports Server (NTRS)

    Grin, E. A.; Fike, D.; Cabrol, N. A.

    2002-01-01

    The morphology and setting of a groove in Gusev strongly supports the hypothesis of a lateral channel generated by meltwater flowing against an ice covered lake margin. The size of the groove and the slope of the bed independent of the topography of the crater are consistent with modest discharges. Additional information is contained in the original extended abstract.

  14. Groundwater transport of crater-lake brine at Poas Volcano, Costa Rica

    USGS Publications Warehouse

    Sanford, W.E.; Konikow, L.F.; Rowe, G.L., Jr.; Brantley, S.L.

    1995-01-01

    This study analyzes the regional groundwater system at Poas and demonstrates the likelihood that the water discharging from the acidic springs in the Rio Agrio watershed originates at the acidic crater lake. Both heat and solute transport are analyzed on a regional scale through numerical simulations using the HST3D finite-difference model, which solves the coupled equations for fluid flow, heat transport, and solute transport. The code allows fluid viscosity and density to be functions of both temperature and solute concentration. The simulations use estimates for recharge to the mountain and a range of values and various distributions of permeability and porosity. Several sensitivity analyses are performed to test how the uncertainty in many of the model parameters affects the simulation results. These uncertainties yield an estimated range of travel times from the crater lake to the Rio Agrio springs of 1-30 yr, which is in close agreement with the results of tritium analyses of the springs. Calculated groundwater fluxes into and out of the crater lake are both about several hundred kg/s. These fluxes must be accounted for in water budgets of the crater lake. -from Authors

  15. Local variation and parallel evolution: morphological and genetic diversity across a species complex of neotropical crater lake cichlid fishes

    PubMed Central

    Elmer, Kathryn R.; Kusche, Henrik; Lehtonen, Topi K.; Meyer, Axel

    2010-01-01

    The polychromatic and trophically polymorphic Midas cichlid fish species complex (Amphilophus cf. citrinellus) is an excellent model system for studying the mechanisms of speciation and patterns of phenotypic diversification in allopatry and in sympatry. Here, we first review research to date on the species complex and the geological history of its habitat. We analyse body shape variation from all currently described species in the complex, sampled from six crater lakes (maximally 1.2–23.9 kyr old) and both great lakes in Nicaragua. We find that Midas cichlid populations in each lake have their own characteristic body shape. In lakes with multiple sympatric species of Midas cichlid, each species has a distinct body shape. Across the species complex, most body shape change relates to body depth, head, snout and mouth shape and caudal peduncle length. There is independent parallel evolution of an elongate limnetic species in at least two crater lakes. Mitochondrial genetic diversity is higher in crater lakes with multiple species. Midas cichlid species richness increases with the size and age of the crater lakes, though no such relationship exists for the other syntopic fishes. We suggest that crater lake Midas cichlids follow the predicted pattern of an adaptive radiation, with early divergence of each crater lake colonization, followed by intralacustrine diversification and speciation by ecological adaptation and sexual selection. PMID:20439280

  16. Comparison of MTI Water Temperatures with Ground Truth Measurements at Crater Lake, OR

    SciTech Connect

    Kurzeja, R.J.

    2002-12-09

    Water surface temperatures calculated with the Los Alamos National Laboratory Robust algorithm were compared with ground truth water temperature measurements near the Oregon State University buoy in Crater Lake, OR. Bulk water measurements at the OSU buoy were corrected for the skin temperature depression and temperature gradient in the top 10 cm of the water to find the water surface temperature for 18 MTI images for June 2000 to Feb 2002. The MTI robust temperatures were found to be biased by 0.1C, with an RMS error of 1.9C compared with the ground truth water surface temperatures. When corrected for the errors in the buoy temperatures the RMS was reduced to 1.3C. This RMS difference is greater than the 1C found at the Pacific Island of Nauru because of the greater variability in the lake temperature and the atmosphere at Crater Lake and the much smaller target area used in the comparison.

  17. Measurements of spectral optical properties and their relation to biogeochemical variables and processes in Crater Lake, Crater Lake National Park, OR

    USGS Publications Warehouse

    Boss, E.S.; Collier, R.; Larson, G.; Fennel, K.; Pegau, W.S.

    2007-01-01

    Spectral inherent optical properties (IOPs) have been measured at Crater Lake, OR, an extremely clear sub-alpine lake. Indeed Pure water IOPs are major contributors to the total IOPs, and thus to the color of the lake. Variations in the spatial distribution of IOPs were observed in June and September 2001, and reflect biogeochemical processes in the lake. Absorption by colored dissolved organic material increases with depth and between June and September in the upper 300 m. This pattern is consistent with a net release of dissolved organic materials from primary and secondary production through the summer and its photo-oxidation near the surface. Waters fed by a tributary near the lake's rim exhibited low levels of absorption by dissolved organic materials. Scattering is mostly dominated by organic particulate material, though inorganic material is found to enter the lake from the rim following a rain storm. Several similarities to oceanic oligotrophic regions are observed: (a) The Beam attenuation correlates well with particulate organic material (POM) and the relationship is similar to that observed in the open ocean. (b) The specific absorption of colored dissolved organic material has a value similar to that of open ocean humic material. (c) The distribution of chlorophyll with depth does not follow the distribution of particulate organic material due to photo-acclimation resulting in a subsurface pigment maximum located about 50 m below the POM maximum. ?? 2007 Springer Science+Business Media B.V.

  18. Suevites from the Rochechouart Impact Crater, France, and the Lake Mien Impact Crater, Sweden: The Search for Robust Carbon Minerals

    NASA Astrophysics Data System (ADS)

    Hough, R. M.; Langenhorst, F.; Stoffler, D.; Pillinger, C. T.; Gilmour, I.

    1995-09-01

    Suevite from the 24km Ries crater in southern Germany has recently been shown to contain diamond, lonsdaleite and silicon carbide (1). These minerals are of impact, not meteoritic, origin and probably formed by a combination of shock and plasma processes with the contribution due to each mechanism yet to be resolved (1). Diamonds are increasingly becoming an accepted impact signature and have been reported for several Ukranian impact craters including Zapadnaya (2) and also for the Popigai impact crater in Siberia (3). We have also found diamonds associated with the K/T boundary event 65 Ma ago in North America (4) and Mexico (5). The genesis of suevite at the Ries is thought to be within a fireball at very high temperatures and travelling at high velocities. Shocked minerals are associated with the suevite as are the high pressure polymorphs of quartz namely coesite and stishovite (6). Such an extreme temperature and pressure history for the suevite make it an ideal rock type to search for impact diamonds, we are therefore endeavouring to study other suevites from further impact craters, including Rochechouart and Mien. The 165-200 Ma Rochechouart impact crater in the Massif Central, France, is thought to have originally been some 20 km across and therefore is very similar in size to the Ries (7). The basement material of gneisses and granites is also akin to the Ries and as such makes it an ideal candidate for diamond poltypes and possibly silicon carbide. Lake Mien in Sweden has no outcrops of suevite breccia but does have glacial erratic blocks of suevite. The impact crater is only some 7-9 km in size and has an age of 120 Ma (8). It affords a useful method of investigating the importance of size as a controlling factor in formation of carbon impact minerals. The samples were treated with an acid demineralization procedure first developed for the extraction of diamond from meteorites and modified for the particular needs of studying terrestrial samples

  19. A new node on the SE Asian paleoclimate map: the alkaline crater lakes of central Myanmar

    NASA Astrophysics Data System (ADS)

    Smittenberg, Rienk H.; Chabangborn, Akkaneewut; Thu Aung, Lin; Fritz, Sherilyn; Wohlfarth, Barbara

    2014-05-01

    SE Asia is climatically a key region where the Asian monsoon system connects with the Indo-Pacific warm pool and from where much (latent) heat gets transported to higher latitudes. We recently obtained sediment cores from four crater lakes located in Central Myanmar, with the aim to further colour the still largely white space on the SE Asian paleoclimate map. The chain of volcanic craters extending northeast to southwest in the vicinity of the lower Chindwin River in central Myanmar have been known for a long time. These craters are aligned west of the Sagaing Fault, which is a continental transform fault between the Indian and Sunda continental plates. Four of the craters still contain lakes, while several of the smaller craters are drained and used for agriculture. The region has a tropical Savannah climate, with warm temperatures throughout the year. Precipitation is almost absent during the dry season but increases to an average monthly precipitation of 100-134 mm per month during the monsoon season (May through October). Three of the four lakes, named Twin Ywa (30 m depth), Twin Taung (60 m), and Twin Pyauk (8m), are highly alkaline (pH 10-11), support extensive cyanobacterial blooms and are anoxic below a few meters water depth. Their sediments are composed of highly organic and laminated algae gyttjas. The shallower (2m), oxic and more neutral (pH 7.5) Lake Leshe contains organic-lean clays but with clear variations in colour and bulk density that likely mark changes in humidity though time. The lake levels of the relatively small crater lakes are solely regulated by precipitation and evaporation, and their limnology and water isotope compositions are therefore sensitive to changes in monsoon intensity. We will present limnological data including water isotopic compositions, and initial bulk sedimentary data as well as preliminary age determinations. These will form the basis for more extensive multi-proxy analyses that should result in an improved insight

  20. Crater lake habitat predicts morphological diversity in adaptive radiations of cichlid fishes.

    PubMed

    Recknagel, Hans; Elmer, Kathryn R; Meyer, Axel

    2014-07-01

    Adaptive radiations provide an excellent opportunity for studying the correlates and causes for the origin of biodiversity. In these radiations, species diversity may be influenced by either the ecological and physical environment, intrinsic lineage effects, or both. Disentangling the relative contributions of these factors in generating biodiversity remains a major challenge in understanding why a lineage does or does not radiate. Here, we examined morphological variation in body shape for replicate flocks of Nicaraguan Midas cichlid fishes and tested its association with biological and physical characteristics of their crater lakes. We found that variability of body elongation, an adaptive trait in freshwater fishes, is mainly predicted by average lake depth (N = 6, P < 0.001, R(2) = 0.96). Other factors considered, including lake age, surface area, littoral zone area, number of co-occurring fish species, and genetic diversity of the Midas flock, did not significantly predict morphological variability. We also showed that lakes with a larger littoral zone have on average higher bodied Midas cichlids, indicating that Midas cichlid flocks are locally adapted to their crater lake habitats. In conclusion, we found that a lake's habitat predicts the magnitude and the diversity of body elongation in repeated cichlid adaptive radiations. PMID:24660780

  1. Persistent Aeolian Activity at Endeavour Crater, Mars

    NASA Astrophysics Data System (ADS)

    Chojnacki, M.; Michaels, T. I.; Fenton, L. K.

    2013-12-01

    Long-term monitoring of sites that are known to have active dunes and ripples is generally limited to 3 Mars-Years (MY). Here, we discuss new results of dune activity and albedo change in Endeavour crater (EC), Meridiani Planum (MP) that record eight MY of aeolian activity. MP dune fields often show large yearly variations in albedo; EC darkened by ~12% in TES albedo between MY 24 and 26 (from 0.14 to 0.12). THEMIS VIS albedo of dunes did not change significantly from MY 26 to 29, but did decrease notably (~15 %) in MY 30. These darkening events are most likely related to aeolian-driven dust cleaning (e.g., removal by saltating sand, dust devils). For example, the Opportunity rover (poised on the western rim of EC) observed evidence for a MY 31 dune field dust-clearing event. HiRISE monitoring of MP has shown it be one of the most active regions outside of north polar latitudes. Paired images of western EC taken 3 MY apart show clear evidence for dune modification that include: ripple migration, change in dune perimeters, exposure of previously buried light-toned rock, and/or burial of rock by sand (Fig. 1a-1b). Dune slip face movement is evident for most dunes, where crests and aprons advanced (2-7 m) in the downwind direction (to the SSE) at rates of 0.7-2.3 m per MY. Small dome dunes in the eastern EC were found to have a large degree of aeolian activity (e.g., deflation and/or translation) by an earlier study that used MGS-MRO images (MY 24-30). New MY 31 images validate earlier observations, showing clear evidence for bedform deflation where dunes often occupy less area (~50%) than in earlier MY 29 images (Fig. 1c-1d). Areal removal rates are on par with earlier estimates. Bedform modification and sand streamer orientation appear to be caused by a NNW wind regime, consistent with earlier observations, mesoscale modeling, and the transport direction of barchans to the west. Dunes in EC are now known to be periodically (consistently?) active from over a decade

  2. Atmospheric optical measurements in the vicinity of crater lake, Oregon. Part I.

    PubMed

    Boileau, A R

    1968-10-01

    This paper presents new atmospheric optical data measured by airborne optical and meteorological sensors recorded near Crater Lake, Oregon, during the first day of a three day period in August 1966. Two data gathering descents were made, from 7800 m to 1400 m, and from 8800 m to 2700 m. The times of these descents were 0913 and 0930 and 1045 to 1101, Pacific Daylight Time. Atmospheric beam transmittances were measured also by a ground station located south of Crater Lake at an altitude of 2070 m. Data presented are altitude profiles of heading of aircraft, temperature, relative humidity, equilibrium luminance, horizontal path function, attenuation length, nadir luminances, and downwelling and upwelling illuminances and their ratios. PMID:20068908

  3. The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results

    NASA Astrophysics Data System (ADS)

    Schaefer, Janet R.; Scott, William E.; Evans, William C.; Jorgenson, Janet; McGimsey, Robert G.; Wang, Bronwen

    2008-07-01

    crater lake has important implications for the study of hazards associated with active volcanic crater lakes.

  4. The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results

    USGS Publications Warehouse

    Schaefer, J.R.; Scott, W.E.; Evans, William C.; Jorgenson, J.; McGimsey, R.G.; Wang, B.

    2008-01-01

    lake has important implications for the study of hazards associated with active volcanic crater lakes. Copyright 2008 by the American Geophysical Union.

  5. Linking lake variability, climate, and human activity in Basotu, Tanzania.

    NASA Astrophysics Data System (ADS)

    Higgins, Lindsey; Westerberg, Lars-Ove; Risberg, Jan

    2016-04-01

    Lake Basotu (4.3697°S, 35.0728°E) is a crater lake in north-central Tanzania. This lake is an important source of freshwater for local people as no perennial rivers are present. Due to intensive agricultural methods and climatic factors, lake level has fluctuated greatly over time. A history of environmental variability of the past 1800 years was established using the diatom record, magnetic parameters, and carbon content from a three meter long sediment core. Fluctuations in modern lake extent (1973 - 2015) were calculated using archived Landsat images and compared to meteorological records and documents of activity around the lake to determine the greatest impacts and their consequences on this essential water resource. Variations in the paleo-record indicate that fluctuations in lake level are not abnormal, however human influence has likely increased the sensitivity of Lake Basotu to climatic fluctuations.

  6. Crater lake cichlids individually specialize along the benthic–limnetic axis

    PubMed Central

    Kusche, Henrik; Recknagel, Hans; Elmer, Kathryn Rebecca; Meyer, Axel

    2014-01-01

    A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of elongated open water (limnetic) species and high-bodied shore (benthic) species from generalist ancestors. Studies on phenotype-diet correlations have suggested that population-wide individual specialization occurs at an early evolutionary and ecological stage of divergence and niche partitioning. This variable restricted niche use across individuals can provide the raw material for earliest stages of sympatric divergence. We investigated variation in morphology and diet as well as their correlations along the benthic-limnetic axis in an extremely young Midas cichlid species, Amphilophus tolteca, endemic to the Nicaraguan crater lake Asososca Managua. We found that A. tolteca varied continuously in ecologically relevant traits such as body shape and lower pharyngeal jaw morphology. The correlation of these phenotypes with niche suggested that individuals are specialized along the benthic-limnetic axis. No genetic differentiation within the crater lake was detected based on genotypes from 13 microsatellite loci. Overall, we found that individual specialization in this young crater lake species encompasses the limnetic-as well as the benthic macro-habitat. Yet there is no evidence for any diversification within the species, making this a candidate system for studying what might be the early stages preceding sympatric divergence. A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of open water (limnetic) species and of shore (benthic) species. Individual specialization can reflect earliest stages of evolutionary and ecological divergence. We here demonstrate individual specialization along the benthic–limnetic axis in a young adaptive radiation of crater lake cichlid fishes. PMID:24772288

  7. Tectonic-karstic origin of the alleged "impact crater" of Lake Isli (Imilchil district, High Atlas, Morocco)

    NASA Astrophysics Data System (ADS)

    Ibouh, Hassan; Michard, André; Charrière, André; Benkaddour, Abdelfattah; Rhoujjati, Ali

    2014-03-01

    The scenic lakes Tislit and Isli of the Imilchil area in the central High Atlas of Morocco have been recently promoted to the rank of "dual impact crater" by a group of geoscientists. This was promptly denied by a group of meteorite specialists, but the first team reiterated their impact crater interpretation, now restricted to Lake Isli. This alleged 40-kyr-old impact crater would be associated with the Agoudal meteorite recognized further in the southeast. Here, we show that the lake formed during the Lowe-Middle Pleistocene in a small Pliocene (?) pull-apart basin through additional collapsing due to karst phenomena in the underlying limestones. This compares with the formation of a number of lakes of the Atlas Mountains. None of the "proofs" produced in support of a meteoritic origin of Lake Isli coincides with the geology of the area.

  8. Crater Lake Apoyo Revisited - Population Genetics of an Emerging Species Flock

    PubMed Central

    Geiger, Matthias F.; McCrary, Jeffrey K.; Schliewen, Ulrich K.

    2013-01-01

    The polytypic Nicaraguan Midas cichlids (Amphilophus cf. citrinellus) have been established as a model system for studying the mechanisms of speciation and patterns of diversification in allopatry and sympatry. The species assemblage in Crater Lake Apoyo has been accepted as a textbook example for sympatric speciation. Here, we present a first comprehensive data set of population genetic (mtDNA & AFLPs) proxies of species level differentiation for a representative set of individuals of all six endemic Amphilophus species occurring in Crater Lake Apoyo. AFLP genetic differentiation was partitioned into a neutral and non-neutral component based on outlier-loci detection approaches, and patterns of species divergence were explored with Bayesian clustering methods. Substantial levels of admixture between species were detected, indicating different levels of reproductive isolation between the six species. Analysis of neutral genetic variation revealed several A. zaliosus as being introgressed by an unknown contributor, hereby rendering the sympatrically evolving L. Apoyo flock polyphyletic. This is contrasted by the mtDNA analysis delivering a clear monophyly signal with Crater Lake Apoyo private haplotypes characterising all six described species, but also demonstrating different demographic histories as inferred from pairwise mismatch distributions. PMID:24086393

  9. Bacterial Diversity in the Soda Saline Crater Lake from Isabel Island, Mexico.

    PubMed

    Aguirre-Garrido, José Félix; Ramírez-Saad, Hugo César; Toro, Nicolás; Martínez-Abarca, Francisco

    2016-01-01

    Isabel Lake is a moderate saline soda crater lake located in Isabel Island in the eastern tropical Pacific coast of Mexico. Lake is mainly formed by rainfall and is strongly affected by evaporation and high input of nutrients derived from excretions of a large bird community inhabiting the island. So far, only the island macrobiota has been studied. The knowledge of the prokaryotic biota inhabiting the upper layers of this meromictic lake can give clues for the maintenance of this ecosystem. We assessed the diversity and composition of prokaryotic community in sediments and water of the lake by DGGE profiling, 16S rRNA gene amplicon pyrosequencing, and cultivation techniques. The bacterial community is largely dominated by halophilic and halotolerant microorganisms. Alpha diversity estimations reveal higher value in sediments than in water (P > 0.005). The lake water is dominated by γ-Proteobacteria belonging to four main families where Halomonadaceae presents the highest abundance. Aerobic, phototrophic, and halotolerant prokaryotes such as Cyanobacteria GPIIa, Halomonas, Alcanivorax, Idiomarina, and Cyclobacterium genera are commonly found. However, in sediment samples, Formosa, Muricauda, and Salegentibacter genera corresponding to Flavobacteriaceae family accounted for 15-20 % of the diversity. Heterotrophs like those involved in sulfur cycle, Desulfotignum, Desulfuromonas, Desulfofustis, and Desulfopila, appear to play an important role in sediments. Finally, a collection of aerobic halophilic bacterial isolates was created from these samples; members of the genus Halomonas were predominantly isolated from lake water. This study contributes to state the bacterial diversity present in this particular soda saline crater lake. PMID:26391805

  10. Geochemistry, mineralogy, and chemical modeling of the acid crater lake of Kawah Ijen Volcano, Indonesia

    NASA Astrophysics Data System (ADS)

    Delmelle, Pierre; Bernard, Alain

    1994-06-01

    The Kawah Ijen volcano—with a record of phreatic eruptions—has its 1000 m wide crater filled with a lake that has existed for at least one century. At present, the lake waters are hot ( T ≈ 37° C), strongly mineralized (TDS = 105 g/L) and extremely acidic ( pH ≈ 0.4). By its volume, the Javanese lake is probably the largest accumulation in the world of such acidic waters. Mineralogy of the suspended solids within the lake waters suggests that concentrations of Si, Ca, Ti, and Ba are controlled by precipitation of silica, gypsum, anatase, and barite. Lake sediment is composed of chemical precipitates with composition similar to the suspended solids. Thermodynamic calculations predict that the lake waters have reached equilibrium with respect to α-cristobalite, barite, gypsum, anglesite, celestite, and amorphous silica, in agreement with the analytical observations. Significant concentrations of ferric iron suggest that the current lake waters are fairly oxidized. Sulfides are absent in the water column but are always present in the native S spherules that form porous aggregates which float on the lake. The presence of native S provides direct evidence of more reduced conditions at the lake floor where H 2S is probably being injected into the lake. With progressive addition of H 2S to the acid waters, native S, pyrite, and enargite are theoretically predicted to be saturated. Reactions between upward streaming H 2S-bearing gases discharged by subaqueous fumaroles, and metals dissolved in the acidic waters could initiate precipitation of these sulfides. A model of direct absorption of hot magmatic gases into cool water accounts for the extreme acidity of the crater lake. Results show that strongly acidic, sulfate-rich solutions are formed under oxidizing conditions at high gas/water ratios. Reactions between the acidic fluids and the Ijen andesite were modeled to account for elevated cation concentrations in lake water. Current concentrations of conservative

  11. Exploration of Microbial Diversity and Community Structure of Lonar Lake: The Only Hypersaline Meteorite Crater Lake within Basalt Rock.

    PubMed

    Paul, Dhiraj; Kumbhare, Shreyas V; Mhatre, Snehit S; Chowdhury, Somak P; Shetty, Sudarshan A; Marathe, Nachiket P; Bhute, Shrikant; Shouche, Yogesh S

    2015-01-01

    Lonar Lake is a hypersaline and hyperalkaline soda lake and the only meteorite impact crater in the world situated in basalt rocks. Although culture-dependent studies have been reported, a comprehensive understanding of microbial community composition and structure in Lonar Lake remains elusive. In the present study, microbial community structure associated with Lonar Lake sediment and water samples was investigated using high-throughput sequencing. Microbial diversity analysis revealed the existence of diverse, yet largely consistent communities. Proteobacteria (30%), Actinobacteria (24%), Firmicutes (11%), and Cyanobacteria (5%) predominated in the sequencing survey, whereas Bacteroidetes (1.12%), BD1-5 (0.5%), Nitrospirae (0.41%), and Verrucomicrobia (0.28%) were detected in relatively minor abundances in the Lonar Lake ecosystem. Within the Proteobacteria phylum, the Gammaproteobacteria represented the most abundantly detected class (21-47%) within sediment samples, but only a minor population in the water samples. Proteobacteria and Firmicutes were found at significantly higher abundance (p ≥ 0.05) in sediment samples, whereas members of Actinobacteria, Candidate division TM7 and Cyanobacteria (p ≥ 0.05) were significantly abundant in water samples. Compared to the microbial communities of other hypersaline soda lakes, those of Lonar Lake formed a distinct cluster, suggesting a different microbial community composition and structure. Here we report for the first time, the difference in composition of indigenous microbial communities between the sediment and water samples of Lonar Lake. An improved census of microbial community structure in this Lake ecosystem provides a foundation for exploring microbial biogeochemical cycling and microbial function in hypersaline lake environments. PMID:26834712

  12. Exploration of Microbial Diversity and Community Structure of Lonar Lake: The Only Hypersaline Meteorite Crater Lake within Basalt Rock

    PubMed Central

    Paul, Dhiraj; Kumbhare, Shreyas V.; Mhatre, Snehit S.; Chowdhury, Somak P.; Shetty, Sudarshan A.; Marathe, Nachiket P.; Bhute, Shrikant; Shouche, Yogesh S.

    2016-01-01

    Lonar Lake is a hypersaline and hyperalkaline soda lake and the only meteorite impact crater in the world situated in basalt rocks. Although culture-dependent studies have been reported, a comprehensive understanding of microbial community composition and structure in Lonar Lake remains elusive. In the present study, microbial community structure associated with Lonar Lake sediment and water samples was investigated using high-throughput sequencing. Microbial diversity analysis revealed the existence of diverse, yet largely consistent communities. Proteobacteria (30%), Actinobacteria (24%), Firmicutes (11%), and Cyanobacteria (5%) predominated in the sequencing survey, whereas Bacteroidetes (1.12%), BD1-5 (0.5%), Nitrospirae (0.41%), and Verrucomicrobia (0.28%) were detected in relatively minor abundances in the Lonar Lake ecosystem. Within the Proteobacteria phylum, the Gammaproteobacteria represented the most abundantly detected class (21–47%) within sediment samples, but only a minor population in the water samples. Proteobacteria and Firmicutes were found at significantly higher abundance (p ≥ 0.05) in sediment samples, whereas members of Actinobacteria, Candidate division TM7 and Cyanobacteria (p ≥ 0.05) were significantly abundant in water samples. Compared to the microbial communities of other hypersaline soda lakes, those of Lonar Lake formed a distinct cluster, suggesting a different microbial community composition and structure. Here we report for the first time, the difference in composition of indigenous microbial communities between the sediment and water samples of Lonar Lake. An improved census of microbial community structure in this Lake ecosystem provides a foundation for exploring microbial biogeochemical cycling and microbial function in hypersaline lake environments. PMID:26834712

  13. Small Changes in Climate Can Profoundly Alter the Dynamics and Ecosystem Services of Tropical Crater Lakes

    PubMed Central

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G.; Efitre, Jackson; Nowlan, Tobias E.; Taranu, Zofia E.; Chapman, Lauren J.

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R2adj = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  14. Small changes in climate can profoundly alter the dynamics and ecosystem services of tropical crater lakes.

    PubMed

    Saulnier-Talbot, Émilie; Gregory-Eaves, Irene; Simpson, Kyle G; Efitre, Jackson; Nowlan, Tobias E; Taranu, Zofia E; Chapman, Lauren J

    2014-01-01

    African tropical lakes provide vital ecosystem services including food and water to some of the fastest growing human populations, yet they are among the most understudied ecosystems in the world. The consequences of climate change and other stressors on the tropical lakes of Africa have been informed by long-term analyses, but these studies have largely focused on the massive Great Rift Valley lakes. Our objective was to evaluate how recent climate change has altered the functioning and services of smaller tropical lakes, which are far more abundant on the landscape. Based on a paired analysis of 20 years of high-resolution water column data and a paleolimnological record from a small crater lake in western Uganda, we present evidence that even a modest warming of the air (∼0.9°C increase over 20 years) and changes in the timing and intensity of rainfall can have significant consequences on the dynamics of this common tropical lake type. For example, we observed a significant nonlinear increase (R(2) adj  = 0.23, e.d.f. = 7, p<0.0001) in thermal stability over the past 20 years. This resulted in the expansion of anoxic waters and consequent deterioration of fish habitat and appears to have abated primary production; processes that may impair ecosystem services for a vulnerable human population. This study on a system representative of small tropical crater lakes highlights the far-reaching effects of global climatic change on tropical waters. Increased research efforts into tropical aquatic ecosystem health and the development of sound management practices are necessary in order to strengthen adaptive capabilities in tropical regions. PMID:24497954

  15. The enigmatic Zerelia twin-lakes (Thessaly, Central Greece): two potential meteorite impact Craters

    NASA Astrophysics Data System (ADS)

    Dietrich, V. J.; Lagios, E.; Reusser, E.; Sakkas, V.; Gartzos, E.; Kyriakopoulos, K.

    2013-09-01

    Two circular permanent lakes of 150 and 250 m diameter and 6-8 m depth to an unconsolidated muddy bottom occur 250 m apart from each other in the agricultural fields SW of the town of Almiros (Thessaly, central Greece). The age of the lakes is assumed to be Late Pliocene to Early Holocene with a minimum age of approx. 7000 yr BP. The abundant polymict, quartz-rich carbonate breccia and clasts with a clay rich matrix in the shallow embankments of the lakes show weak stratification but no volcanic structures. The carbonate clasts and particles often display spheroidal shapes and consist of calcite aggregates with feathery, arborescent, variolitic to micro-sparitic textures and spheroidal fabrics, recrystallized and deformed glass-shaped fragments, calcite globules in quartz; thus indications of possible carbonate melting, quenching and devitrification. The carbonatic matrix includes small xenomorphic phases, such as chromspinel, zircon with blurred granular and skeletal textures, skeletal rutile and ilmenite, which are interpreted as relicts of partial melting and quenching under high temperatures of 1240-1800 °C. Only a few quartz fragments exhibit indistinct planar fractures. In several cases they include exotic Al-Si- and sulfur bearing Fe-phases, < 1-10 μm as globules. The modeled "Residual Gravity" profiles through the lakes indicate negative gravity anomalies of bowl-type structures down to 150 m for the eastern lake and down to 250 m for the larger western lake. Several hypotheses can be drawn upon to explain the origin of these enigmatic twin-lakes: (a) Maar-type volcanic craters; (b) hydrothermal or CO2/hydrocarbon gas explosion craters; (c) and (d) doline holes due to karstification; or (e) small meteorite impact craters, the latter being a plausible explanation due to geologic, petrologic, and geophysical evidence. The morphology and dimensions of the lakes as well as the density contrast tomography of the bedrock favor a meteorite impact hypothesis of a

  16. Expressions of climate perturbations in western Ugandan crater lake sediment records during the last 1000 years

    NASA Astrophysics Data System (ADS)

    Mills, K.; Ryves, D. B.; Anderson, N. J.; Bryant, C. L.; Tyler, J. J.

    2014-08-01

    Equatorial East Africa has a complex regional patchwork of climate regimes, sensitive to climate fluctuations over a variety of temporal and spatial scales during the late Holocene. Understanding how these changes are recorded in and interpreted from biological and geochemical proxies in lake sedimentary records remains a key challenge to answering fundamental questions regarding the nature, spatial extent and synchroneity of climatic changes seen in East African palaeo-records. Using a paired lake approach, where neighbouring lakes share the same geology, climate and landscape, it might be expected that the systems will respond similarly to external climate forcing. Sediment cores from two crater lakes in western Uganda spanning the last ~1000 years were examined to assess diatom community responses to late Holocene climate and environmental changes, and to test responses to multiple drivers using redundancy analysis (RDA). These archives provide annual to sub-decadal records of environmental change. Lakes Nyamogusingiri and Kyasanduka appear to operate as independent systems in their recording of a similar hydrological response signal via distinct diatom records. However, whilst their fossil diatom records demonstrate an individualistic, indirect response to external (e.g. climatic) drivers, the inferred lake levels show similar overall trends and reflect the broader patterns observed in Uganda and across East Africa. The lakes appear to be sensitive to large-scale climatic perturbations, with evidence of a dry Medieval Climate Anomaly (MCA; ca. AD 1000-1200). The diatom record from Lake Nyamogusingiri suggests a drying climate during the main phase of the Little Ice Age (LIA) (ca. AD 1600-1800), whereas the diatom response from the shallower Lake Kyasanduka is more complex (with groundwater likely playing a key role), and may be driven more by changes in silica and other nutrients, rather than by lake level. The sensitivity of these two Ugandan lakes to regional

  17. Nitrincola nitratireducens sp. nov. isolated from a haloalkaline crater lake.

    PubMed

    Singh, Aditya; Vaidya, Bhumika; Tanuku, Naga Radha Srinivas; Pinnaka, Anil Kumar

    2015-12-01

    The novel, cream coloured, Gram-negative-staining, rod-shaped, motile bacteria, designated strains AK23(T) and AK28, were isolated from sediment samples collected from Lonar Lake, Buldhana district, India. The predominant fatty acids were C18:1ω7c, C16:0, C10:0 3OH and C16:1ω7c and/or iso-C15:0 2OH (summed feature 3). Polar lipid content of strains AK23(T) and AK28 were found to be phosphatidylethanolamine (PE), phosphatidylglycerol (PG), phosphotidylserine (PS), one unidentified phospholipid (PL) and two unidentified lipids (L1 and L2). The 16S rRNA gene sequence analysis indicated strains AK23(T) and AK28 as the members of the genus Nitrincola and closely related to the type strain Nitrincola lacisaponensis with pair-wise sequence similarity of 97.67% and 97.62% respectively. DNA-DNA hybridization between strain AK23(T) and AK28 showed a relatedness of 91%. Genome of strains AK23(T) and N. lacisaponensis DSM 16316(T) were sequenced. A comparative genomics approach was used to study strains AK23(T), N. lacisaponensis DSM 16316(T) and five other phylogenetic neighbours. The genome size of N. lacisaponensis DSM 16316(T) was found to be 614,784bp smaller than that of the strain AK23(T). This variation could be due to multiple reasons, gene uptake, evolution, mutation, genome reduction phenomenon and draft nature of sequencing. Based on data from the current polyphasic study, strains AK23(T) and AK28 are proposed as novel species of the genus Nitrincola, for which the name Nitrincola nitratireducens sp. nov. is proposed. The type strain of N. nitratireducens is AK23(T) (=JCM 18788(T)=MTCC 11628(T)). PMID:26481633

  18. Cruise report R/V Surf Surveyor cruise S1-00-CL, mapping the bathymetry of Crater Lake, Oregon

    USGS Publications Warehouse

    Gardner, James V.; Mayer, Larry A.; Buktenica, Mark W.

    2000-01-01

    During the Spring of 1999, the US Geological Survey (USGS) Pacific Seafloor Mapping Project (PSMP) was contacted by the US National Park Service Crater Lake National Park (CLNP) to inquire about the plausibility of producing a high-resolution multibeam bathymetric map of Crater Lake. The purpose was to generate a much higher-resolution and more geographically accurate bathymetric map than was produced in 1959, the last time the lake had been surveyed. Scientific interest in various aspects of Crater Lake (aquatic biology, geochemistry, volcanic processes, etc.) has increased during the past decade but the basemap of bathymetry was woefully inadequate. Funds were gathered during the early part of 2000 and the mapping began in late July, 2000. Crater Lake (see fig. 1 in report) is located in south central Oregon (see fig. 2 in report) within the Cascades Range, a chain of volcanoes that stretches from northern California to southern British Columbia. Crater Lake is the collapsed caldera of Mt. Mazama from a climatic eruption about 7700-yr ago (Nelson et al., 1988; Bacon and Lanphere, 1990; Bacon et al., 1997). The floor of Crater Lake has only been mapped three times since the lake was first stumbled upon by gold prospectors in the 1853. The first survey was carried by out by William G. Steel during a joint USGS-US Army expedition under the direction of Maj. Clarence E. Dutton in 1886 (Dutton, 1889). Steel�s mapping survey collected 186 soundings using a Millers lead-line sounding machine (see fig.3 in report). The resulting map (see fig.4 in report) shows only soundings and no attempts were made to generate contours. The second survey, conducted in 1959 by the US Coast and Geodetic Survey, mapped the bathymetry of Crater Lake with an acoustic echo sounder using radar navigation and collected 4000 soundings. The data were contoured by Williams (1961) and Byrne (1962) and the result is a fairly detailed map of the large-scale features of Crater Lake (see fig. 5

  19. 2000 Multibeam Sonar Survey of Crater Lake, Oregon - Data, GIS, Images, and Movies

    USGS Publications Warehouse

    Gardner, James V.; Dartnell, Peter

    2001-01-01

    In the summer of 2000, the U.S. Geological Survey, Pacific Seafloor Mapping Project in cooperation with the National Park Service, and the Center for Coastal and Ocean Mapping, University of New Hampshire used a state-of-the-art multibeam sonar system to collect high-resolution bathymetry and calibrated, co-registered acoustic backscatter to support both biological and geological research in the Crater Lake area. This interactive CD-ROM contains the multibeam bathymetry and acoustic backscatter data, along with an ESRI ArcExplorer project (and software), images, and movies.

  20. Atmospheric optical measurements in the vicinity of crater lake, Oregon. Part 2.

    PubMed

    Boileau, A R

    1968-11-01

    This paper, Part 2, presents additional atmospheric optical data, comparable to the data presented in Part 1, but for a different type of day, and for four descents instead of two. All descents were before local apparent noon. Simultaneous spectral irradiance data were recorded at the surface of Crater Lake. Data presented are altitude profiles of heading of aircraft, temperature, relative humidity, equilibrium luminance, horizontal path function, attenuation length, nadir luminance, upwelling and downwelling illuminances and their ratios, reflectance calculated from nadir luminance, atmospheric beam transmittances for vertical path of sight as a function of solar zenith angle, and downwelling illuminance as a function of solar zenith angle. PMID:20068978

  1. A symbiotic view of the origin of life at hydrothermal impact crater-lakes.

    PubMed

    Chatterjee, Sankar

    2016-07-27

    Submarine hydrothermal vents are generally considered as the likely habitats for the origin and evolution of early life on Earth. The theory suffers from the 'concentration problem' of cosmic and terrestrial biomolecules because of the vastness of the Eoarchean global ocean. An attractive alternative site would be highly sequestered, small, hydrothermal crater-lakes that might have cradled life on early Earth. A new symbiotic model for the origin of life at hydrothermal crater-lakes is proposed here. Meteoritic impacts on the Eoarchean crust at the tail end of the Heavy Bombardment period might have played important roles in the origin of life. Impacts and collisions that created hydrothermal crater lakes on the Eoarchean crust inadvertently became the perfect crucibles for prebiotic chemistry with building blocks of life, which ultimately led to the first organisms by prebiotic synthesis. In this scenario, life arose through four hierarchical stages of increasing molecular complexity in multiple niches of crater basins. In the cosmic stage (≥4.6 Ga), the building blocks of life had their beginnings in the interstellar space during the explosion of a nearby star. Both comets and carbonaceous chondrites delivered building blocks of life and ice to early Earth, which were accumulated in hydrothermal impact crater-lakes. In the geologic stage (∼4 Ga), crater basins contained an assortment of cosmic and terrestrial organic compounds, powered by hydrothermal, solar, tidal, and chemical energies, which drove the prebiotic synthesis. At the water surface, self-assembled primitive lipid membranes floated as a thick oil slick. Archean Greenstone belts in Greenland, Australia, and South Africa possibly represent the relics of these Archean craters, where the oldest fossils of thermophilic life (∼3.5 Ga) have been detected. In the chemical stage, monomers such as nucleotides and amino acids were selected from random assemblies of the prebiotic soup; they were

  2. The timing of alluvial activity in Gale crater, Mars

    NASA Astrophysics Data System (ADS)

    Grant, John A.; Wilson, Sharon A.; Mangold, Nicolas; Calef, Fred; Grotzinger, John P.

    2014-02-01

    The Curiosity rover's discovery of rocks preserving evidence of past habitable conditions in Gale crater highlights the importance of constraining the timing of responsible depositional settings to understand the astrobiological implications for Mars. Crater statistics and mapping reveal the bulk of the alluvial deposits in Gale, including those interrogated by Curiosity, were likely emplaced during the Hesperian, thereby implying that habitable conditions persisted after the Noachian. Crater counting data sets and upper Peace Vallis fan morphology also suggest a possible younger period of fluvial activation that deposited ~10-20 m of sediments on the upper fan after emplacement of the main body of the fan. If validated, water associated with later alluvial activity may have contributed to secondary diagenetic features in Yellowknife Bay.

  3. Successful Completion of Pre-Site Survey for Deep Drilling at El'gygytgyn Crater Lake

    NASA Astrophysics Data System (ADS)

    Melles, M.; Minyuk, P.; Brigham-Grette, J.; Niessen, F.

    2003-12-01

    Lake El'gygytgyn, located in central Chukotka, NE Russia, is a 3.6 million year old impact crater lake with a diameter of 12 km and a water depth of 170 m. The sedimentary record of the lake has become a major focus of multi-disciplinary multi-national paleoclimatic research and is now a potential target for deep drilling. A full-length sediment core would yield a complete record of Arctic climate evolution, back one million years prior to the first major glaciation of the Northern Hemisphere. Geomorphological evidence from the catchment suggests that the crater was never glaciated during the entire Late Cenozoic. A 13.0 m long sediment core retrieved from the deepest part of the lake in 1998 revealed a basal age of approx. 300 ka, confirmed the lack of glacial erosion, and underlined the sensitivity of this lacustrine environment to reflect high resolution climatic change. The first single channel seismic survey carried out in 2000 discovered undisturbed and well-stratified sediments to a depth of 160 m below the lake floor. Refraction data from sonobuoys indicated the top of the impact breccia at about 360 m subbottom. An ICDP workshop held in 2001 recognised the unique potential of the lake for both paleoclimate and impact-related research and suggested more site survey work. This final pre-site survey expedition took place from April to September 2003. Modern process studies of the lake hydrology, limnology, meteorology, and sedimentology took place over this entire period to better understand the various proxies we are using to decipher the paleoclimate record of the sediment fill. Geomorphic and permafrost studies of lake and river terrace stratigraphies contribute to our understanding of climate dependent landscape evolution. A 16 m long sediment core from the central part of the lake presumably extents the existing record towards more than 400 ka BP. The matching of proxies from this core and the core recovered in 1998 illustrates the lateral continuity of

  4. Holocene palaeoecology of the Golan Heights (Near East): investigation of lacustrine sediments from Birkat Ram crater lake

    NASA Astrophysics Data System (ADS)

    Schwab, Markus J.; Neumann, Frank; Litt, Thomas; Negendank, Jorg F. W.; Stein, Mordechai

    2004-09-01

    Lacustrine deposits of the crater lake Birkat Ram located in the northern Golan Heights have been used as a paleoecological archive. Preliminary sedimentological and palynological investigations based on a composite profile allow the reconstruction of the environmental history of the last 6500 years. Fluctuations of the pollen composition (trees and shrubs versus herbs, values of oak and olive tree) correspond to changes in different sediment parameters (total organic carbon, magnetic susceptibility) which can be interpreted as the effects of human impact on the geo-biosphere. Four phases with strong settlement activities can be identified for the Northern Golan Heights: (1) during the Chalcolithic period/Early Bronze Age, (2) during the Hellenistic-Roman-Byzantine periods, (3) during the Crusader period, and finally during modern time. These periods were interrupted by wooded regeneration phases with low anthropogenic activities.

  5. Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.A.

    NASA Astrophysics Data System (ADS)

    Bacon, Charles R.

    1983-10-01

    New investigations of the geology of Crater Lake National Park necessitate a reinterpretation of the eruptive history of Mount Mazama and of the formation of Crater Lake caldera. Mount Mazama consisted of a glaciated complex of overlapping shields and stratovolcanoes, each of which was probably active for a comparatively short interval. All the Mazama magmas apparently evolved within thermally and compositionally zoned crustal magma reservoirs, which reached their maximum volume and degree of differentiation in the climactic magma chamber ˜ 7000 yr B.P. The history displayed in the caldera walls begins with construction of the andesitic Phantom Cone ˜ 400,000 yr B.P. Subsequently, at least 6 major centers erupted combinations of mafic andesite, andesite, or dacite before initiation of the Wisconsin Glaciation ˜ 75,000 yr B.P. Eruption of andesitic and dacitic lavas from 5 or more discrete centers, as well as an episode of dacitic pyroclastic activity, occurred until ˜ 50,000 yr B.P.; by that time, intermediate lava had been erupted at several short-lived vents. Concurrently, and probably during much of the Pleistocene, basaltic to mafic andesitic monogenetic vents built cinder cones and erupted local lava flows low on the flanks of Mount Mazama. Basaltic magma from one of these vents, Forgotten Crater, intercepted the margin of the zoned intermediate to silicic magmatic system and caused eruption of commingled andesitic and dacitic lava along a radial trend sometime between ˜ 22,000 and ˜ 30,000 yr B.P. Dacitic deposits between 22,000 and 50,000 yr old appear to record emplacement of domes high on the south slope. A line of silicic domes that may be between 22,000 and 30,000 yr old, northeast of and radial to the caldera, and a single dome on the north wall were probably fed by the same developing magma chamber as the dacitic lavas of the Forgotten Crater complex. The dacitic Palisade flow on the northeast wall is ˜ 25,000 yr old. These relatively silicic

  6. Genomic islands of speciation separate cichlid ecomorphs in an East African crater lake.

    PubMed

    Malinsky, Milan; Challis, Richard J; Tyers, Alexandra M; Schiffels, Stephan; Terai, Yohey; Ngatunga, Benjamin P; Miska, Eric A; Durbin, Richard; Genner, Martin J; Turner, George F

    2015-12-18

    The genomic causes and effects of divergent ecological selection during speciation are still poorly understood. Here we report the discovery and detailed characterization of early-stage adaptive divergence of two cichlid fish ecomorphs in a small (700 meters in diameter) isolated crater lake in Tanzania. The ecomorphs differ in depth preference, male breeding color, body shape, diet, and trophic morphology. With whole-genome sequences of 146 fish, we identified 98 clearly demarcated genomic "islands" of high differentiation and demonstrated the association of genotypes across these islands with divergent mate preferences. The islands contain candidate adaptive genes enriched for functions in sensory perception (including rhodopsin and other twilight-vision-associated genes), hormone signaling, and morphogenesis. Our study suggests mechanisms and genomic regions that may play a role in the closely related mega-radiation of Lake Malawi. PMID:26680190

  7. Genomic islands of speciation separate cichlid ecomorphs in an East African crater lake*

    PubMed Central

    Tyers, Alexandra M.; Schiffels, Stephan; Terai, Yohey; Ngatunga, Benjamin P.; Miska, Eric A.; Durbin, Richard; Genner, Martin J.; Turner, George F.

    2015-01-01

    The genomic causes and effects of divergent ecological selection during speciation are still poorly understood. Here, we report the discovery and detailed characterization of early-stage adaptive divergence of two cichlid fish ecomorphs in a small (700m diameter) isolated crater lake in Tanzania. The ecomorphs differ in depth preference, male breeding color, body shape, diet and trophic morphology. With whole genome sequences of 146 fish, we identify 98 clearly demarcated genomic ‘islands’ of high differentiation and demonstrate association of genotypes across these islands to divergent mate preferences. The islands contain candidate adaptive genes enriched for functions in sensory perception (including rhodopsin and other twilight vision associated genes), hormone signaling and morphogenesis. Our study suggests mechanisms and genomic regions that may play a role in the closely related mega-radiation of Lake Malawi. PMID:26680190

  8. Multiparameter Monitoring Techniques for Reducing Volcanic Risk from Cuicocha Crater Lake, Ecuador

    NASA Astrophysics Data System (ADS)

    Ruiz, A. G.; Samaniego, P.; von Hillebrandt-Andrade, C.; Hall, M. L.; Ruiz, M. C.; Mothes, P. A.; Macias, C. A.

    2013-05-01

    Cuicocha, a crater-lake volcano located 50 km north of Quito, had an explosive caldera eruption 3000 yBP (Hillebrandt, 1989) that affected an important area of the northern part of the Ecuadorian Interandean valley. The first seismic station was installed at Cuicocha in 1988. Since 2010, this volcano showed an increase of their seismic activity, with several earthquakes felt by inhabitants near the volcano, as well as a subtle increase of the CO2 gas emission. After that, the Instituto Geofisico initiated a program for improving the monitoring capacity combined with a new geological field work dataset. Three broad band stations were installed, two of them outside the caldera rim and the other one, CUIC station, is located just over the Yerovi island dome. Two continuous GPS stations NetRS were installed, one 5 km east of Cuicocha and the other inside the caldera. On Yerovi dome it was deployed a permanent CO2 spectrometer. The Instituto Geofisico carries out a periodically EDM and gas measurements on the volcano in order to correlate geodesic data set and degasing CO2 flux. At the same time, we are re-evaluating the eruptive chronology and the eruptive dynamisms of the Cuicocha caldera eruptions, as well as the petrology of the paroxysmal eruptive products. Preliminary results confirm the 3000 yBP eruption age and our current work will be able to constraint the dynamisms, frequency and size of this paroxysmal eruption of Cuicocha. Finally, we plan to use all this information to re-edit the hazard map (von Hillebrandt and Hall, 1988) and guide local authorities and population to reduce the volcanic risk.

  9. Eruptive history of Mount Mazama and Crater Lake Caldera, Cascade Range, U.S.A.

    USGS Publications Warehouse

    Bacon, C.R.

    1983-01-01

    New investigations of the geology of Crater Lake National Park necessitate a reinterpretation of the eruptive history of Mount Mazama and of the formation of Crater Lake caldera. Mount Mazama consisted of a glaciated complex of overlapping shields and stratovolcanoes, each of which was probably active for a comparatively short interval. All the Mazama magmas apparently evolved within thermally and compositionally zoned crustal magma reservoirs, which reached their maximum volume and degree of differentiation in the climactic magma chamber ??? 7000 yr B.P. The history displayed in the caldera walls begins with construction of the andesitic Phantom Cone ??? 400,000 yr B.P. Subsequently, at least 6 major centers erupted combinations of mafic andesite, andesite, or dacite before initiation of the Wisconsin Glaciation ??? 75,000 yr B.P. Eruption of andesitic and dacitic lavas from 5 or more discrete centers, as well as an episode of dacitic pyroclastic activity, occurred until ??? 50,000 yr B.P.; by that time, intermediate lava had been erupted at several short-lived vents. Concurrently, and probably during much of the Pleistocene, basaltic to mafic andesitic monogenetic vents built cinder cones and erupted local lava flows low on the flanks of Mount Mazama. Basaltic magma from one of these vents, Forgotten Crater, intercepted the margin of the zoned intermediate to silicic magmatic system and caused eruption of commingled andesitic and dacitic lava along a radial trend sometime between ??? 22,000 and ??? 30,000 yr B.P. Dacitic deposits between 22,000 and 50,000 yr old appear to record emplacement of domes high on the south slope. A line of silicic domes that may be between 22,000 and 30,000 yr old, northeast of and radial to the caldera, and a single dome on the north wall were probably fed by the same developing magma chamber as the dacitic lavas of the Forgotten Crater complex. The dacitic Palisade flow on the northeast wall is ??? 25,000 yr old. These relatively

  10. Simulation of deep ventilation in Crater Lake, Oregon, 1951–2099

    USGS Publications Warehouse

    Wood, Tamara M.; Wherry, Susan A.; Piccolroaz, Sebastiano; Girdner, Scott F

    2016-01-01

    The frequency of deep ventilation events in Crater Lake, a caldera lake in the Oregon Cascade Mountains, was simulated in six future climate scenarios, using a 1-dimensional deep ventilation model (1DDV) that was developed to simulate the ventilation of deep water initiated by reverse stratification and subsequent thermobaric instability. The model was calibrated and validated with lake temperature data collected from 1994 to 2011. Wind and air temperature data from three general circulation models and two representative concentration pathways were used to simulate the change in lake temperature and the frequency of deep ventilation events in possible future climates. The lumped model air2water was used to project lake surface temperature, a required boundary condition for the lake model, based on air temperature in the future climates.The 1DDV model was used to simulate daily water temperature profiles through 2099. All future climate scenarios projected increased water temperature throughout the water column and a substantive reduction in the frequency of deep ventilation events. The least extreme scenario projected the frequency of deep ventilation events to decrease from about 1 in 2 years in current conditions to about 1 in 3 years by 2100. The most extreme scenario considered projected the frequency of deep ventilation events to be about 1 in 7.7 years by 2100. All scenarios predicted that the temperature of the entire water column will be greater than 4 °C for increasing lengths of time in the future and that the conditions required for thermobaric instability induced mixing will become rare or non-existent.The disruption of deep ventilation by itself does not provide a complete picture of the potential ecological and water quality consequences of warming climate to Crater Lake. Estimating the effect of warming climate on deep water oxygen depletion and water clarity will require careful modeling studies to combine the physical mixing processes affected by

  11. Indications of fluid immiscibility in glass from West Clearwater Lake impact crater, Quebec, Canada

    NASA Technical Reports Server (NTRS)

    Dence, M. R.; Von Engelhardt, W.; Plant, A. G.; Walter, L. S.

    1974-01-01

    Glass from the West Clearwater Lake hypervelocity impact crater contains numerous spheroids, 10 to 500 microns across, which appear to have formed at high temperatures as fluids immiscible in the enclosing melt. The spheroids are distinguished from small, normal, largely void gas vesicles, which are also present, by being completely filled in all cases; by having fillings which vary in composition from spheroid to spheroid, even between spheroids in close association; and by indications that the present fillings are representative of the contents present before the matrix melt chilled. Most of the spheroids are classified petrographically into three types. The preservation of spheroids in the West Clearwater Lake glass is attributed mainly to the position of the glass masses within the breccias lining the crater floor. It is considered that the glass in this location did not achieve free flight but, as part of a large mass, cooled relatively slowly through the high temperature regime in which the spheroids were generated, and then, when detached, chilled rapidly to preserve a record of this transient stage in their history.

  12. Connections between hyper-acid crater lakes and flank springs: new evidence from Rincón de la Vieja volcano (Costa Rica)

    NASA Astrophysics Data System (ADS)

    Martínez, M.; Fernández, E.; Sáenz, W.; van Bergen, M. J.; Ayres, G.; Pacheco, J. F.; Brenes, J.; Avard, G.; Malavassi, E.

    2012-04-01

    Rincón de la Vieja, a complex andesitic stratovolcano in NW Costa Rica, shows various hydrothermal surface manifestations that comprise: (1) A hyper-acid crater lake and subaerial fumaroles receiving direct input of fluids of magmatic origin, (2) Acid thermal discharges along the northeastern slopes of the volcano that feed the headwaters of the Cucaracho river, and (3) Small lakes and a geothermal field with bubbling-boiling mud pools, acid-sulfate springs, steaming ground and fumarolic emissions in a region on the western flank. Here the streams are of relatively low flow rate and their chemical signatures correspond to that of deep fluids from an extensive geothermal reservoir mixed with shallow meteoric water. Physico-chemical properties of the sulfate-chloride hyper-acid lake (T=28-58 °C; pH between 1.2 and <0, high TDS of 24,000-160,000 mg/kg) are consistent with a meteoric water body supplied by a significant input of chemical components derived from hydrolysis of magmatic volatiles and from intense rock leaching. The Cucaracho catchment receives input from warm acid brines with no free-gas phase but carrying a high load of hydrolyzed magmatic volatiles and rock-forming elements. One of these brines (Spring 4) is characterized by a sulfate-chloride chemical signature, medium temperatures of 27-38 °C, pH between 2 and 4 and TDS values between 780 and 1300 mg/L. Based on water and heat-balance considerations, chemical and stable-isotope signatures and groundwater transport modeling, it has been proposed that these acid springs represent brine water from the lake-hydrothermal system that is diluted by shallow groundwater permeating tephra layers (Kempter and Rowe, 2000). Since Rincóńs latest phreatomagmatic activity in 1983, episodes of phreatic eruptions from the crater lake have been registered in 1983-87, 1991, 1995, 1998 and 2011. Some of these eruptions (VEI 1) have expelled large quantities of lake water, triggering small to medium- sized fast

  13. Multibeam Sonar Mapping and Modeling of a Submerged Bryophyte Mat in Crater Lake, Oregon

    USGS Publications Warehouse

    Dartnell, Peter; Collier, Robert; Buktenica, Mark; Jessup, Steven; Girdner, Scott; Triezenberg, Peter

    2008-01-01

    Traditionally, multibeam data have been used to map sea floor or lake floor morphology as well as the distribution of surficial facies in order to characterize the geologic component of benthic habitats. In addition to using multibeam data for geologic studies, we want to determine if these data can also be used directly to map the distribution of biota. Multibeam bathymetry and acoustic backscatter data collected in Crater Lake, Oregon, in 2000 are used to map the distribution of a deep-water bryophyte mat, which will be extremely useful for understanding the overall ecology of the lake. To map the bryophyte's distribution, depth range, acoustic backscatter intensity, and derived bathymetric index grids are used as inputs into a hierarchical decision-tree classification model. Observations of the bryophyte mat from over 23 line kilometers of lake-floor video collected in the summer of 2006 are used as controls for the model. The resulting map matches well with ground-truth information and shows that the bryophyte mat covers most of the platform surrounding Wizard Island as well as on outcrops around the caldera wall.

  14. Hydrothermal and tectonic activity in northern Yellowstone Lake, Wyoming

    USGS Publications Warehouse

    Johnson, S.Y.; Stephenson, W.J.; Morgan, L.A.; Shanks, Wayne C.; Pierce, K.L.

    2003-01-01

    Yellowstone National Park is the site of one of the world's largest calderas. The abundance of geothermal and tectonic activity in and around the caldera, including historic uplift and subsidence, makes it necessary to understand active geologic processes and their associated hazards. To that end, we here use an extensive grid of high-resolution seismic reflection profiles (???450 km) to document hydrothermal and tectonic features and deposits in northern Yellowstone Lake. Sublacustrine geothermal features in northern Yellowstone Lake include two of the largest known hydrothermal explosion craters, Mary Bay and Elliott's. Mary Bay explosion breccia is distributed uniformly around the crater, whereas Elliott's crater breccia has an asymmetric distribution and forms a distinctive, ???2-km-long, hummocky lobe on the lake floor. Hydrothermal vents and low-relief domes are abundant on the lake floor; their greatest abundance is in and near explosion craters and along linear fissures. Domed areas on the lake floor that are relatively unbreached (by vents) are considered the most likely sites of future large hydrothermal explosions. Four submerged shoreline terraces along the margins of northern Yellowstone Lake add to the Holocene record or postglacial lake-level fluctuations attributed to "heavy breathing" of the Yellowstone magma reservoir and associated geothermal system. The Lake Hotel fault cuts through northwestern Yellowstone Lake and represents part of a 25-km-long distributed extensional deformation zone. Three postglacial ruptures indicate a slip rate of ???0.27 to 0.34 mm/yr. The largest (3.0 m slip) and most recent event occurred in the past ???2100 yr. Although high heat flow in the crust limits the rupture area of this fault zone, future earthquakes of magnitude ???5.3 to 6.5 are possible. Earthquakes and hydrothermal explosions have probably triggered landslides, common features around the lake margins. Few high-resolution seismic reflection surveys have

  15. Simulation of Deep Water Renewal in Crater Lake, Oregon, USA under Current and Future Climate Conditions

    NASA Astrophysics Data System (ADS)

    Piccolroaz, S.; Wood, T. M.; Wherry, S.; Girdner, S.

    2015-12-01

    We applied a 1-dimensional lake model developed to simulate deep mixing related to thermobaric instabilities in temperate lakes to Crater Lake, a 590-m deep caldera lake in Oregon's Cascade Range known for its stunning deep blue color and extremely clear water, in order to determine the frequency of deep water renewal in future climate conditions. The lake model was calibrated with 6 years of water temperature profiles, and then simulated 10 years of validation data with an RMSE ranging from 0.81°C at 50 m depth to 0.04°C at 350-460 m depth. The simulated time series of heat content in the deep lake accurately captured extreme years characterized by weak and strong deep water renewal. The lake model uses wind speed and lake surface temperature (LST) as boundary conditions. LST projections under six climate scenarios from the CMIP5 intermodel comparison project (2 representative concentration pathways X 3 general circulation models) were evaluated with air2water, a simple lumped model that only requires daily values of downscaled air temperature. air2water was calibrated with data from 1993-2011, resulting in a RMSE between simulated and observed daily LST values of 0.68°C. All future climate scenarios project increased water temperature throughout the water column and a substantive reduction in the frequency of deepwater renewal events. The least extreme scenario (CNRM-CM5, RCP4.5) projects the frequency of deepwater renewal events to decrease from about 1 in 2 years in the present to about 1 in 3 years by 2100. The most extreme scenario (HadGEM2-ES, RCP8.5) projects the frequency of deepwater renewal events to be less than 1 in 7 years by 2100 and lake surface temperatures never cooling to less than 4°C after 2050. In all RCP4.5 simulations the temperature of the entire water column is greater than 4°C for increasing periods of time. In the RCP8.5 simulations, the temperature of the entire water column is greater than 4°C year round by the year 2060 (HadGEM2

  16. High-resolution digital elevation dataset for Crater Lake National Park and vicinity, Oregon, based on LiDAR survey of August-September 2010 and bathymetric survey of July 2000

    USGS Publications Warehouse

    Robinson, Joel E.

    2012-01-01

    Crater Lake partially fills the caldera that formed approximately 7,700 years ago during the eruption of a 12,000-foot volcano known as Mount Mazama. The caldera-forming or climactic eruption of Mount Mazama devastated the surrounding landscape, left a thick deposit of pumice and ash in adjacent valleys, and spread a blanket of volcanic ash as far away as southern Canada. Because the Crater Lake region is potentially volcanically active, knowledge of past events is important to understanding hazards from future eruptions. Similarly, because the area is seismically active, documenting and evaluating geologic faults is critical to assessing hazards from earthquakes. As part of the American Recovery and Reinvestment Act (ARRA) of 2009, the U.S. Geological Survey was awarded funding for high-precision airborne LiDAR (Light Detection And Ranging) data collection at several volcanoes in the Cascade Range through the Oregon LiDAR Consortium, administered by the Oregon Department of Geology and Mineral Industries (DOGAMI). The Oregon LiDAR Consortium contracted with Watershed Sciences, Inc., to conduct the data collection surveys. Collaborating agencies participating with the Oregon LiDAR Consortium for data collection in the Crater Lake region include Crater Lake National Park (National Park Service) and the Federal Highway Administration. In the immediate vicinity of Crater Lake National Park, 798 square kilometers of LiDAR data were collected, providing a digital elevation dataset of the ground surface beneath forest cover with an average resolution of 1.6 laser returns/m2 and both vertical and horizontal accuracies of ±5 cm. The LiDAR data were mosaicked in this report with bathymetry of the lake floor of Crater Lake, collected in 2000 using high-resolution multibeam sonar in a collaborative effort between the U.S. Geological Survey, Crater Lake National Park, and the Center for Coastal and Ocean Mapping at the University of New Hampshire. The bathymetric survey

  17. Shallow outgassing changes disrupt steady lava lake activity, Kilauea Volcano

    NASA Astrophysics Data System (ADS)

    Patrick, M. R.; Orr, T. R.; Swanson, D. A.; Lev, E.

    2015-12-01

    Persistent lava lakes are a testament to sustained magma supply and outgassing in basaltic systems, and the surface activity of lava lakes has been used to infer processes in the underlying magmatic system. At Kilauea Volcano, Hawai`i, the lava lake in Halema`uma`u Crater has been closely studied for several years with webcam imagery, geophysical, petrological and gas emission techniques. The lava lake in Halema`uma`u is now the second largest on Earth, and provides an unprecedented opportunity for detailed observations of lava lake outgassing processes. We observe that steady activity is characterized by continuous southward motion of the lake's surface and slow changes in lava level, seismic tremor and gas emissions. This normal, steady activity can be abruptly interrupted by the appearance of spattering - sometimes triggered by rockfalls - on the lake surface, which abruptly shifts the lake surface motion, lava level and gas emissions to a more variable, unstable regime. The lake commonly alternates between this a) normal, steady activity and b) unstable behavior several times per day. The spattering represents outgassing of shallowly accumulated gas in the lake. Therefore, although steady lava lake behavior at Halema`uma`u may be deeply driven by upwelling of magma, we argue that the sporadic interruptions to this behavior are the result of shallow processes occurring near the lake surface. These observations provide a cautionary note that some lava lake behavior is not representative of deep-seated processes. This behavior also highlights the complex and dynamic nature of lava lake activity.

  18. Subaerial and sublacustrine hydrothermal activity at Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Stucker, Valerie K.; de Ronde, Cornel E. J.; Scott, Bradley J.; Wilson, Nathaniel J.; Walker, Sharon L.; Lupton, John E.

    2016-03-01

    Lake Rotomahana is a crater lake in the Okataina Volcanic Centre (New Zealand) that was significantly modified by the 1886 Tarawera Rift eruption. The lake is host to numerous sublacustrine hydrothermal vents. Water column studies were conducted in 2011 and 2014 along with sampling of lake shore hot springs and crater lakes in Waimangu Valley to complement magnetic, seismic, bathymetric and heat flux surveys. Helium concentrations below 50 m depth are higher in 2014 compared to 2011 and represent some of the highest concentrations measured, at 6 × 10- 7 ccSTP/g, with an end-member 3He/4He value of 7.1 RA. The high concentrations of helium, when coupled with pH anomalies due to high dissolved CO2 content, suggest the dominant chemical input to the lake is derived from magmatic degassing of an underlying magma. The lake shore hot spring waters show differences in source temperatures using a Na-K geothermometer, with inferred reservoir temperatures ranging between 197 and 232 °C. Water δ18O and δD values show isotopic enrichment due to evaporation of a steam heated pool with samples from nearby Waimangu Valley having the greatest enrichment. Results from this study confirm both pre-1886 eruption hydrothermal sites and newly created post-eruption sites are both still active.

  19. Brownish discoloration of the summit crater lake of Mt. Shinmoe-dake, Kirishima Volcano, Japan: volcanic-microbial coupled origin

    NASA Astrophysics Data System (ADS)

    Ohsawa, Shinji; Sugimori, Kenji; Yamauchi, Hiroshi; Koeda, Tomoyuki; Inaba, Hiroaki; Kataoka, Yoshihisa; Kagiyama, Tsuneomi

    2014-05-01

    A drastic change in lake water color from blue-green to brown was observed in the summit crater lake of Mt. Shinmoe-dake, Kirishima Volcano about 8 months after its 2008 eruption. The color change lasted for about 2 months (April-June 2009). The discoloration was attributed to a brownish color suspension that had formed in the lake water. X-ray fluorescence and Fourier transform infrared analyses of a sample of the suspension identified schwertmannite (Fe8O8(OH)6(SO4)). A cultivation test of iron-oxidizing bacteria for the sampled lake water with lakebed sediment revealed that the crater lake hosts iron-oxidizing bacteria, which likely participated in schwertmannite formation. We suggest that pyrite (FeS2) provided an energy source for the iron-oxidizing bacteria since the mineral was identified in hydrothermally altered tephra ejected by the August 2008 eruption. From consideration of these and other factors, the brownish discoloration of the summit crater lake of Mt. Shinmoe-dake was inferred to have resulted from a combined volcanic-microbial process.

  20. Faults, Post-1720 Explosion Craters, and the Remains of a Lava Lake at Castro Bank Seamount (E Azores)

    NASA Astrophysics Data System (ADS)

    Wunderman, R.; Barriga, F. J.; Nishimura, C.; Pacheco, J. M.; Vogt, P. R.; Gaspar, J. L.; Queiroz, G.; Santos, R.

    2003-12-01

    During 25-28 July 2003 the US Navy submarine NR-1 dove on the seamount D. Joao de Castro Bank, compiling reconnaissance sonar and visual data. Castro Bank sits along strike and between the eastern Azorian islands of Terceira and S. Miguel, occupying a seismically active region ˜60 km from each of these islands and apparently controlled by the same underlying tectonics as other islands found along the Azores' northern margin. Castro Bank's last recorded eruptions built a ˜1 km diameter ephemeral island in the 1720s. The bathimetry of the uppermost 40 m or so of the Bank is rather well known via single beam sonar, scuba diving and AUV surveys (IH, DOP/UA and ISR/IST, unpublished work). Our dives compiled data in concentric rings along contours, collecting side- and forward-looking sonar along an overall track length of ˜20 km, with the deepest ring approaching ˜200 m depth. To document key features we came near the sea floor and took videos in water with typical visibility of ˜10-15 m. This is the first progress report on our work, which found the edifice morphologically complex and irregular. We noted that the seamount was often covered by aerially extensive yellow-brown hyaloclastic tuffs that were presumably products of the 1720s eruption, but also cut by faults and fissures (with offsets of ten's of meters) exposing abundant areas of older edifice. The faults typically lacked sediment cover, and in one case a very fresh, sediment-free fault trended along the base of a steep cliff. This suggested the faults were much younger than the 1720 eruption, an observation in accord with intense seismicity recorded in this area. The faults provided exposures of older rocks, which included abundant breccia and lesser clearly identified pillows or thick lava flows. The NW quadrant contains two small, shallow, elliptical craters. These lie side-by-side and crosscut inferred 1720s-age tuffs. One crater held a lava lake, the body of which apparently withdrew or subsided

  1. Hydrogeochemical monitoring of El Chichón Volcano crater lake, Mexico.

    NASA Astrophysics Data System (ADS)

    Ceniceros, N.; Armienta, M. A.; Ramos, S.; Cruz, O.; Aguayo, A.

    2003-04-01

    The geochemistry of the crater lake of the El Chichón volcano has been studied since 1983. Results have been used to analyze post-eruptive processes and assessing volcanic risk. Chemical analysis has included pH, temperature, principal ions, fluoride, Iron , sulfide, boron and Silica. From 1985, all determinations have been performed at the Analytical Chemistry Laboratory of the Geophysics Institute (National University of Mexico). Such analysis were made following the standard methods, as given in APHA (1989), e.g. UV-visible, emission, and atomic absorption spectroscopy, potentiometric and volumetric techniques.. The El Chichón crater lake water showed an increasing pH from 1983 to 1986 (from 0.56 to 2.33), from then pH has fluctuated around the later value (in August 2002 pH was 1.98). Conductivity showed a high fluctuations with a general decreasing trend, ranging between 83800 uS/cm (1983, Casadevall et al., 1984) and close to 2000 uS/cm (December 1998). Water-type has changed along these years: The Chichon water could be classified as acid, calcium-chloride in 1983; in 1991 changed to Sulfate-mixed and since 1992, it has been mostly of sodium chloride type, except for a few dates when it could be classified as sulfate-mixed or calcic type. Since 1985, cation concentrations produced by environmental rock dissolution decreased in the same manner. A decreasing trend with time was observed also in anions of a potential magmatic origin like sulfate, chloride and fluoride. Molar concentrations of chloride have been mostly greater than sulfate concentrations (up to two orders of magnitude) and have varied without any observed correlation. Oxidation-reduction processes may explain the large sulfate concentration changesSulfate shows large. The geochemical modeling programs (MINTEQA2, PHREEQCE) showed saturation indices close to equilibrium for gypsum and anhydrite suggesting that sulfates also can be derived from other processes such as dissolution

  2. Pleistocene Lake Bonneville and Eberswalde Crater of Mars: Quantitative Methods for Recognizing Poorly Developed Lacustrine Shorelines

    NASA Astrophysics Data System (ADS)

    Jewell, P. W.

    2014-12-01

    The ability to quantify shoreline features on Earth has been aided by advances in acquisition of high-resolution topography through laser imaging and photogrammetry. Well-defined and well-documented features such as the Bonneville, Provo, and Stansbury shorelines of Late Pleistocene Lake Bonneville are recognizable to the untrained eye and easily mappable on aerial photos. The continuity and correlation of lesser shorelines must rely quantitative algorithms for processing high-resolution data in order to gain widespread scientific acceptance. Using Savitsky-Golay filters and the geomorphic methods and criteria described by Hare et al. [2001], minor, transgressive, erosional shorelines of Lake Bonneville have been identified and correlated across the basin with varying degrees of statistical confidence. Results solve one of the key paradoxes of Lake Bonneville first described by G. K. Gilbert in the late 19th century and point the way for understanding climatically driven oscillations of the Last Glacial Maximum in the Great Basin of the United States. Similar techniques have been applied to the Eberswalde Crater area of Mars using HRiSE DEMs (1 m horizontal resolution) where a paleolake is hypothesized to have existed. Results illustrate the challenges of identifying shorelines where long term aeolian processes have degraded the shorelines and field validation is not possible. The work illustrates the promises and challenges of indentifying remnants of a global ocean elsewhere on the red planet.

  3. Geochemical monitoring of Chichón volcano (México) trough sulfur speciation of the crater lake's water

    NASA Astrophysics Data System (ADS)

    Casas, Ana Silvia; Aurora Armienta, Maria; Guadalupe Ramos, Silvia

    2015-04-01

    Monitoring of El Chichón volcanic activity is a very important given its eruption of March 28th, 1982 that was the worst volcanic disaster of the modern era in Mexico. To help mitigation of volcanic risk, we intend the establishment of an analytical methodology for the determining various sulfur species (S2-, SO3 2-, S4O6 2-, SO4 2-) occurring in the crater lake which was formed after the 1982 eruption. These species were determined through HPL Chromatography with the aim of establishing links between their presence and concentrations, the general physical and chemical characteristics of the lake, seasonal variations and the activity of El Chichón volcano. Besides, knowledge of sulfur species behavior will contribute to have a better knowledge of the state the hydrothermal system, and the internal dynamics of the volcano, and provide more information to determine periods of increasing hazard. This paper presents advances in the development of the methodologies for the analysis of the above mentioned sulfur species. We have identified the analytical procedures for sampling and analysis of these species (preservation, operating conditions of the equipment, number of samples, dilution, etc.) according to various studies in different volcanoes with crater lakes (Volcano Poas, Costa Rica; Kusatsu-Shirane, Japan). Water samples collected at various locations of the lake on March 29th, and July 11th and October 3rd, 2014, have been analyzed for major ions and sulfur species. Results are being related to the volcanic behavior. Results obtained: Average concentrations (mg/L) at one sampling site: • Sulphide: 1.75 in March, 1.82 in July and 4.99 in October • Sulphite: 4.16 in March, 1.89 in July and 25.23 in October • Tetrathionate: 236.88 in March, 247.46 in July and 152.96 in October • Sulphate: 618.51 in March, 609.91 in July and 620.18 in October Preliminary conclusions: • The proposed Chromatographic method has been successful to separate these sulfur

  4. Genetic linkage of distinct adaptive traits in sympatrically speciating crater lake cichlid fish.

    PubMed

    Fruciano, Carmelo; Franchini, Paolo; Kovacova, Viera; Elmer, Kathryn R; Henning, Frederico; Meyer, Axel

    2016-01-01

    Our understanding of how biological diversity arises is limited, especially in the case of speciation in the face of gene flow. Here we investigate the genomic basis of adaptive traits, focusing on a sympatrically diverging species pair of crater lake cichlid fishes. We identify the main quantitative trait loci (QTL) for two eco-morphological traits: body shape and pharyngeal jaw morphology. These traits diverge in parallel between benthic and limnetic species in the repeated adaptive radiations of this and other fish lineages. Remarkably, a single chromosomal region contains the highest effect size QTL for both traits. Transcriptomic data show that the QTL regions contain genes putatively under selection. Independent population genomic data corroborate QTL regions as areas of high differentiation between the sympatric sister species. Our results provide empirical support for current theoretical models that emphasize the importance of genetic linkage and pleiotropy in facilitating rapid divergence in sympatry. PMID:27597183

  5. Origin of phenocrysts and compositional diversity in pre-Mazama rhyodacite lavas, Crater Lake, Oregon

    USGS Publications Warehouse

    Nakada, S.; Bacon, C.R.; Gartner, A.E.

    1994-01-01

    Phenocrysts in porphyritic volcanic rocks may originate in a variety of ways in addition to nucleation and growth in the matrix in which they are found. Porphyritic rhyodacite lavas that underlie the eastern half of Mount Mazama, the High Cascade andesite/dacite volcano that contains Crater Lake caldera, contain evidence that bears on the general problem of phenocryst origin. Phenocrysts in these lavas apparently formed by crystallization near the margins of a magma chamber and were admixed into convecting magma before eruption. About 20 km3 of pre-Mazama rhyodacite magma erupted during a relatively short period between ~400 and 500 ka; exposed pre-Mazama dacites are older and less voluminous. The rhyodacites formed as many as 40 lava domes and flows that can be assigned to three eruptive groups on the basis of composition and phenocryst content. -from Authors

  6. Lake evolution during the Early Danian Dan-C2 hyperthermal, Boltysh impact crater, Ukraine

    NASA Astrophysics Data System (ADS)

    Ebinghaus, Alena; Jolley, David W.

    2016-04-01

    Lacustrine facies record complex relationships between lake evolution and environmental conditions and provide proxies for climate changes. However, lacustrine successions formed during past hyperthermals as recorded from negative carbon isotope excursions (CIEs) are of limited availability and thus less well understood. Here, we present a complete lacustrine record of the Early Danian Dan-C2 hyperthermal at c. 65.2 Ma from a core drilled in the K-Pg Boltysh impact crater, Ukraine. This borehole allows a detailed facies analysis and reconstruction of lake evolution and associated plant ecosystem in correspondence with rapid climate change. The Boltysh borehole reveals a c. 400 m thick siliciclastic and organic-rich succession overlying impact melt-breccia dated at 65.17 ± 0.64 Ma. Based on detailed core logging, 8 distinctive facies associations are identified, including 1) littoral mudstones, 2) siliciclastic shoreline deposits, 3) siliciclastic littoral to sublittoral deposits, 4) mudstone laminites, 5) organic-rich mudstones, and deposits of 6) coarse-grained, 7) fine-grained density currents, and 8) debris flows. Based on the occurrence of these facies associations 3 major phases of lake evolution are distinguished: 1) an initial pre-CIE rising clastic-dominated lake phase characterised by the presence of coarse-grained density and debris flow deposits, 2) an organic-rich fluctuating shallow lake phase during the main phase of the CIE, characterised by alternating packages of the mudstone laminites and organic-rich mudstones; and 3) a rising clastic-dominated lake during and post-CIE recovery phase, which shows a high presence of siliciclastic shoreline and littoral to sublittoral deposits. This study provides a full record of lacustrine response to climate change during the Dan-C2 hyperthermal, and subsequently allows us to infer lake formation and environmental conditions at different stages during climate warming. The high resolution sedimentary record

  7. Lithic breccia and ignimbrite erupted during the collapse of Crater Lake Caldera, Oregon

    USGS Publications Warehouse

    Druitt, T.H.; Bacon, C.R.

    1986-01-01

    The climactic eruption of Mount Mazama (6845 y.B.P.) vented a total of ???50 km3 of compositionally zoned rhyodacitic to basaltic magma from: (a) a single vent as a Plinian pumice fall deposit and the overlying Wineglass Welded Tuff, and (b) ring vents as ignimbrite and coignimbrite lithic breccia accompanying the collapse of Crater Lake caldera. New field and grain-size data for the ring-vent products are presented in this report. The coarse-grained, poorly bedded, clast-supported lithic breccia extends as far as 18 km from the caldera center. Like the associated ignimbrite, the breccia is compositionally zoned both radially and vertically, and silicic, mixed, and mafic types can be recognized, based on the proportion of rhyodacitic pumice. Matrix fractions in silicic breccias are depleted of fines and are lithic- and crystal-enriched relative to silicic ignimbrite due to vigorous gas sorting during emplacement. Ignimbrite occurs as a proximal veneer deposit overlying the breccia, a medial (??? 8 to ??? 25 km from the caldera center), compositionally zoned valley fill as much as > 110 m thick, and an unzoned distal ({slanted equal to or greater-than} 20 km) facies which extends as far as 55 km from the caldera. Breccia within ??? 9 km of the caldera center is interpreted as a coignimbrite lag breccia formed within the deflation zone of the collapsing ring-vent eruption columns. Expanded pyroclastic flows of the deflation zone were probably vertically graded in both size and concentration of blocks, as recently postulated for some turbidity currents. An inflection in the rate of falloff of lithic-clast size within the lithic breccia at ??? 9 km may mark the outer edge of the deflation zone or may be an artifact of incomplete exposure. The onset of ring-vent activity at Mt. Mazama was accompanied by a marked increase in eruptive discharge. Pyroclastic flows were emplaced as a semicontinuous stream, as few ignimbrite flow-unit boundaries are evident. As eruption from

  8. Impact Craters in North America

    NASA Astrophysics Data System (ADS)

    Grieve, R. A. F.; Wood, C. A.; Garvin, J. B.; McLaughlin, G.; McHone, J. F.

    1988-03-01

    Meteor Crater Upheaval Dome Sierra Madera Middlesboro Pilot Lake Carswell Gow Lake Deep Bay Nicholson Lake West Hawk Lake Haughton Sudbury Wanapitei Brent Lac Couture New Quebec Clearwater Lakes Manicouagan Charlevoix Lac La Moinerie Mistastin

  9. Monitoring direct and indirect climate effects on whitebark pine ecosystems at Crater Lake National park

    USGS Publications Warehouse

    Smith, S.B.; Odion, D.C.; Sarr, D.A.; Irvine, K.M.

    2011-01-01

    Whitebark pine (Pinus albicaulis) is the distinctive, often stunted, and picturesque tree line species in the American West. As a result of climate change, mountain pine beetles (Dendroctonus ponderosae) have moved up in elevation, adding to nonnative blister rust (Cronartium ribicola) disease as a major cause of mortality in whitebark pine. At Crater Lake National Park, Oregon, whitebark pine is declining at the rate of 1% per year. The Klamath Network, National Park Service, has elected to monitor whitebark pine and associated high-elevation vegetation. This program is designed to sample whitebark pine throughout the park to look for geographic patterns in its exposure to and mortality from disease and beetles. First-year monitoring has uncovered interesting patterns in blister rust distribution. Incidence of rust disease was higher on the west side of the park, where conditions are wetter and more humid than on the east side. However, correlating climate alone with rust disease is not straightforward. On the east side of the park, the odds of blister rust infection were much greater in plots having Ribes spp., shrubs that act as the alternate host for a portion of the rust's life cycle. However, on the park's west side, there was not a statistically significant increase in blister rust in plots with Ribes. This suggests that different species of Ribes associated with whitebark pine can increase pine exposure to blister rust disease. There is also convincing evidence of an association between total tree density and the incidence of blister rust. Warmer temperatures and possibly increased precipitation will affect both whitebark pine and Ribes physiology as well as tree density and mountain pine beetle numbers, all of which may interact with blister rust to cause future changes in tree line communities at Crater Lake. The Klamath Network monitoring program plans to document and study these ongoing changes.

  10. Breccia Formation at a Complex Impact Crater: Slate Islands, Lake Superior, Ontario, Canada

    NASA Technical Reports Server (NTRS)

    Dressler, B. O.; Sharpton, V. L.

    1997-01-01

    The Slate Islands impact structure is the eroded remnant of a approximately 30-32 km-diameter complex impact structure located in northern Lake Superior, Ontario, Canada. Target rocks are Archean supracrustal and igneous rocks and Proterozoic metavolcanics, metasediments, and diabase. A wide variety of breccias occurs on the islands, many of which contain fragments exhibiting shock metamorphic features. Aphanitic, narrow and inclusion-poor pseudotachylite veins, commonly with more or less parallel boundaries and apophyses branching off them, represent the earliest breccias formed during the compression stage of the impact process. Coarse-grained, polymictic elastic matrix breccias form small to very large, inclusion-rich dikes and irregularly shaped bodies that may contain altered glass fragments. These breccias have sharp contacts with their host rocks and include a wide range of fragment types some of which were transported over minimum distances of approximately 2 km away from the center of the structure. They cut across pseudotachylite veins and contain inclusions of them. Field and petrographic evidence indicate that these polymictic breccias formed predominantly during the excavation and central uplift stages of the impact process. Monomictic breccias, characterized by angular fragments and transitional contacts with their host rocks, occur in parautochthonous target rocks, mainly on the outlying islands of the Slate Islands archipelago. A few contain fragmented and disrupted, coarse-grained, polymictic clastic matrix breccia dikes. This is an indication that at least some of these monomictic breccias formed late in the impact process and that they are probably related to a late crater modification stage. A small number of relatively large occurrences of glass-poor, suevitic breccias occur at the flanks of the central uplift and along the inner flank of the outer ring of the Slate Islands complex crater. A coarse, glass-free, allogenic breccia, containing

  11. Breccia formation at a complex impact crater: Slate Islands, Lake Superior, Ontario, Canada

    NASA Astrophysics Data System (ADS)

    Dressler, B. O.; Sharpton, V. L.

    1997-07-01

    The Slate Islands impact structure is the eroded remnant of a ˜30-32 km-diameter complex impact structure located in northern Lake Superior, Ontario, Canada. Target rocks are Archean supracrustal and igneous rocks and Proterozoic metavolcanics, metasediments, and diabase. A wide variety of breccias occurs on the islands, many of which contain fragments exhibiting shock metamorphic features. Aphanitic, narrow and inclusion-poor pseudotachylite veins, commonly with more or less parallel boundaries and apophyses branching off them, represent the earlist breccias formed during the compression stage of the impact process. Coarse-grained, polymictic clastic matrix breccias form small to very large, inclusion-rich dikes and irregularly shaped bodies that may contain altered glass fragments. These breccias have sharp contacts with their host rocks and include a wide range of fragment types some of which were transported over minimum distances of ˜2 km away from the center of the structure. They cut across pseudotachylite veins and contain inclusions of them. Field and petrographic evidence indicate that these polymictic breccias formed predominantly during the excavation and central uplift stages of the impact process. Monomictic breccias, characterized by angular fragments and transitional contacts with their host rocks, occur in parautochthonous target rocks, mainly on the outlying islands of the Slate Islands archipelago. A few contain fragmented and disrupted, coarse-grained, polymictic clastic matrix breccia dikes. This is an indication that at least some of these monomictic breccias formed late in the impact process and that they are probably related to a late crater modification stage. A small number of relatively large occurrences of glass-poor, suevitic breccias occur at the flanks of the central uplift and along the inner flank of the outer ring of the Slate Islands complex crater. A coarse, glass-free, allogenic breccia, containing shatter-coned fragments

  12. Measuring volcanic gases at Taal Volcano Main Crater for monitoring volcanic activity and possible gas hazard

    NASA Astrophysics Data System (ADS)

    Arpa, M.; Hernandez Perez, P. A.; Reniva, P.; Bariso, E.; Padilla, G.; Melian Rodriguez, G.; Barrancos, J.; Calvo, D.; Nolasco, D.; Padron, E.; Garduque, R.; Villacorte, E.; Fajiculay, E.; Perez, N.; Solidum, R.

    2012-12-01

    Taal is an active volcano located in southwest Luzon, Philippines. It consists of mainly tuff cones which have formed an island at the center of a 30 km wide Taal Caldera. Most historical eruptions, since 1572 on Taal Volcano Island, have been characterized as hydromagmatic eruptions. Taal Main Crater, produced during the 1911 eruption, is the largest crater in the island currently filled by a 1.2 km wide, 85 m deep acidic lake. The latest historical eruption occurred in 1965-1977. Monitoring of CO2 emissions from the Main Crater Lake (MCL) and fumarolic areas within the Main Crater started in 2008 with a collaborative project between ITER and PHIVOLCS. Measurements were done by accumulation chamber method using a Westsystem portable diffuse fluxmeter. Baseline total diffuse CO2 emissions of less than 1000 t/d were established for the MCL from 3 campaign-type surveys between April, 2008 to March, 2010 when seismicity was within background levels. In May, 2010, anomalous seismic activity from the volcano started and the total CO2 emission from the MCL increased to 2716±54 t/d as measured in August, 2010. The CO2 emission from the lake was highest last March, 2011 at 4670±159 t/d when the volcano was still showing signs of unrest. Because CO2 emissions increased significantly (more than 3 times the baseline value) at this time, this activity may be interpreted as magmatic and not purely hydrothermal. Most likely deep magma intrusions occurred but did not progress further to shallower depths and no eruption occurred. No large increase in lake water temperature near the surface (average for the whole lake area) during the period when CO2 was above background, it remained at 30-34°C and a few degrees lower than average ambient temperature. Total CO2 emissions from the MCL have decreased to within baseline values since October, 2011. Concentrations of CO2, SO2 and H2S in air in the fumarolic area within the Main Crater also increased in March, 2011. The measurements

  13. Summit crater lake observations, and the location, chemistry, and pH of water samples near Mount Chiginagak volcano, Alaska: 2004-2012

    USGS Publications Warehouse

    Schaefer, Janet R.; Scott, William E.; Evans, William C.; Wang, Bronwen; McGimsey, Robert G.

    2013-01-01

    Mount Chiginagak is a hydrothermally active volcano on the Alaska Peninsula, approximately 170 km south–southwest of King Salmon, Alaska (fig. 1). This small stratovolcano, approximately 8 km in diameter, has erupted through Tertiary to Permian sedimentary and igneous rocks (Detterman and others, 1987). The highest peak is at an elevation of 2,135 m, and the upper ~1,000 m of the volcano are covered with snow and ice. Holocene activity consists of debris avalanches, lahars, and lava flows. Pleistocene pyroclastic flows and block-and-ash flows, interlayered with andesitic lava flows, dominate the edifice rocks on the northern and western flanks. Historical reports of activity are limited and generally describe “steaming” and “smoking” (Coats, 1950; Powers, 1958). Proximal tephra collected during recent fieldwork suggests there may have been limited Holocene explosive activity that resulted in localized ash fall. A cluster of fumaroles on the north flank, at an elevation of ~1,750 m, commonly referred to as the “north flank fumarole” have been emitting gas throughout historical time (location shown in fig. 2). The only other thermal feature at the volcano is the Mother Goose hot springs located at the base of the edifice on the northwestern flank in upper Volcano Creek, at an elevation of ~160 m (fig. 2, near sites H1, H3, and H4). Sometime between November 2004 and May 2005, a ~400-m-wide, 100-m-deep lake developed in the snow- and ice-filled summit crater of the volcano (Schaefer and others, 2008). In early May 2005, an estimated 3 million cubic meters (3×106 m3) of sulfurous, clay-rich debris and acidic water exited the crater through tunnels at the base of a glacier that breaches the south crater rim. More than 27 km downstream, these acidic flood waters reached approximately 1.3 m above normal water levels and inundated a fertile, salmon-spawning drainage, acidifying the entire water column of Mother Goose Lake from its surface waters to its

  14. Sedimentary Record of the Last two Interglacials in the Terrestrial Canadian Arctic (Pingualuit Crater Lake, Nunavik)

    NASA Astrophysics Data System (ADS)

    St-Onge, G.; Guyard, H.; Pienitz, R.; Hausmann, S.; Francus, P.; Salonen, V.; Luoto, T.; Black, J.; Lamothe, M.; Zolitschka, B.; Larocque, I.

    2009-05-01

    The Pingualuit crater lake (Nunavik, Canada) resulted from a meteoritic impact that occurred ca. 1.4 million years ago. Due to its unique morphometry (depth and shape), the lake bottom may have escaped glacial erosion. Based on a punctual seismic profile acquired using a 12 kHz Knudsen echosounder and using both gravity and piston corers, we recovered the uppermost 8.5 m of sediments. High-resolution physical (CAT- Scan, Multi Sensor Core Logger, diffuse spectral reflectance), geochemical (ITRAX core scanner, carbon and nitrogen contents, δ13C of the organic matter) and magnetic (magnetic susceptibility, natural, anhysteretic, isothermal and saturation isothermal remanent magnetizations) analyses were performed. Two main lithofacies were clearly identified by the different measurements and likely represent successive interglacial/glacial cycles. Most of the sediment consists of light grey silts containing several angular rock fragments, that is characterized by very low organic carbon content, relatively high density and magnetic susceptibility values, suggesting a deposition during glacial conditions. Interbedded between this facies are at least two decimetre-thick, organic-rich and finely laminated intervals likely representing ice free periods. The presence of diatoms, chrysophytes and chironomid head capsules in smear and microscope slides from these two intervals supports this hypothesis. In addition, preliminary Infrared Stimulated Luminescence (IRSL) measurements indicate that the upper organic-rich layer has an age coeval with the last interglacial (Oxygen Isotope Stage 5), while the age of the lower organic-rich layer is consistent with an older interglacial, likely the Oxygen Isotope Stage 7. The sedimentary infill thus constitutes a unique long-term terrestrial record of environmental and climatic conditions in the Canadian Arctic. Furthermore, because these sediments escaped glacial erosion, it suggests the presence of a subglacial lake during the last

  15. Vernal Crater, SW Arabia Terra: MSL Candidate with Extensively Layered Sediments, Possible Lake Deposits, and a Long History of Subsurface Ice

    NASA Technical Reports Server (NTRS)

    Oehler, Dorothy Z.; Allen, Carlton C.

    2007-01-01

    Vernal Crater is a Mars Science Laboratory (MSL) landing site candidate providing relatively easy access to extensively layered sediments as well as potential lake deposits. Sediments of Vernal Crater are 400-1200 m below those being investigated by Opportunity in Meridiani Planum, and as such would allow study of significantly older geologic units, if Vernal Crater were selected for MSL. The location of Vernal Crater in SW Arabia Terra provides exceptional scientific interest, as rampart craters and gamma-ray spectrometer (GRS) data from the region suggest a long history of ice/fluids in the subsurface. The potential value of this MSL candidate is further enhanced by reports of atmospheric methane over Arabia, as any insight into the source of that methane would significantly increase our understanding of Mars. Finally, should MSL survive beyond its prime mission, the gentle slope within Vernal Crater would provide a route out of the crater for study of the once ice/fluid-rich plains.

  16. Lava Lake Level Drop and Related Ground Subsidence in the Nyiragongo Main Crater (D.R.Congo) Measured by Close-Range Photogrammetry and InSAR Time-Series

    NASA Astrophysics Data System (ADS)

    Smets, B.; d'Oreye, N.; Samsonov, S. V.; Nobile, A.; Geirsson, H.; Kervyn, F.

    2015-12-01

    Nyiragongo volcano is the most active African volcano and among the most active volcanoes on Earth. It is also among the infrequent volcanoes that host a long-lived lava lake. The morphology of the Nyiragongo main crater is characterized by 2 levels of remnant platforms partly preserved and attached to its inner flanks, which correspond to former lava lake levels, and by a bottom "active" platform, which delimits the current active lava lake. The elevation of the bottom platform increases through time, with successive lava lake overflows. After a period of low level between late 2010 and August 2011, the lava lake next came back to its highest level. However, on September 30, 2011, it started a long and progressive fall, reaching ~70 m below the bottom platform in July 2014. This recent evolution of the lava lake, which occurred at the same time period as eruptive events at the neighboring Nyamulagira volcano, was accompanied by a ground subsidence of the bottom platform, leading to the appearance of ring fissures. This ground deformation is restricted to the bottom platform and, hence, suggests a very shallow source for the observed movement. All these changes in the Nyiragongo main crater were recorded by time-series of photographs, allowing the 3D reconstruction of the crater using close-range photogrammetric techniques and, hence, a detailed measurement of the observed changes. The ground subsidence was also recorded by time-series of RADARSAT-2 and CosmoSky-Med SAR interferograms, providing more detailed information on the velocity of deformation. Based on field data and the photogrammetric and InSAR time-series measurements, several hypotheses on the cause(s) of these changes in the Nyiragongo crater are discussed. The present work also highlights the potential of close-range photogrammetry and high-resolution InSAR to study and monitor active volcanoes in Equatorial environment.

  17. Circulation patterns in active lava lakes

    NASA Astrophysics Data System (ADS)

    Redmond, T. C.; Lev, E.

    2014-12-01

    Active lava lakes provide a unique window into magmatic conduit processes. We investigated circulation patterns of 4 active lava lakes: Kilauea's Halemaumau crater, Mount Erebus, Erta Ale and Nyiragongo, and in an artificial "lava lake" constructed at the Syracuse University Lava Lab. We employed visual and thermal video recordings collected at these volcanoes and use computer vision techniques to extract time-dependent, two-dimensional surface velocity maps. The large amount of data available from Halemaumau enabled us to identify several characteristic circulation patterns. One such pattern is a rapid acceleration followed by rapid deceleration, often to a level lower than the pre-acceleration level, and then a slow recovery. Another pattern is periodic asymmetric peaks of gradual acceleration and rapid deceleration, or vice versa, previously explained by gas pistoning. Using spectral analysis, we find that the dominant period of circulation cycles at approximately 30 minutes, 3 times longer than the dominant period identified previously for Mount Erebus. Measuring a complete surface velocity field allowed us to map and follow locations of divergence and convergence, therefore upwelling and downwelling, thus connecting the surface flow with that at depth. At Nyiragongo, the location of main upwelling shifts gradually, yet is usually at the interior of the lake, for Erebus it is usually along the perimeter yet often there is catastrophic downwelling at the interior; For Halemaumau upwelling/downwelling position is almost always on the perimeter. In addition to velocity fields, we developed an automated tool for counting crustal plates at the surface of the lava lakes, and found a correlation, and a lag time, between changes if circulation vigor and the average size of crustal plates. Circulation in the artificial basaltic lava "lake" was limited by its size and degree of foaming, yet we measured surface velocities and identify patterns. Maximum surface velocity

  18. Evaluation, Proposed Solution and Current Status of the Crater Lake Breakout Problem, Mount Pinatubo, Philippines

    NASA Astrophysics Data System (ADS)

    Bornas, M. A.

    2001-12-01

    Rapid rise of Mount Pinatubo's crater lake and recent geological assessments of the crater's lowest point, the Maraunot Notch, raised concern about a breakout lahar down the northwestern slope of the volcano. Three factors indicated a serious hazard. First, the lake rose about 50 m from May 98-August 2001 and was expected to overtop the Maraunot Notch within the last trimester 2001. Overtopping might well have occurred at the height of a strong typhoon or under heavy monsoonal rainstorms. Second, the uppermost 10-20 m of "dam" was erodible ash and poorly indurated coarse breccia, susceptible to failure by overtopping and erosion as at many landslide and other natural dams. Third, the volumes of lake discharge corresponding to 10 and 20 m of erosion would have been 28 and 55 million m3; peak discharges at a breach could have been as high as 3,200 m3/sec to 11,000 m3/sec, respectively. These discharges would have eroded 1991 pyroclastic and lahar material on the volcano's slopes, increased the flow volume by 3-6x, and entered the Bucao River as a large-magnitude lahar. The Municipality of Botolan (pop. ca. 40,000) lies on the delta of the Bucao River valley some 40 km downriver from the notch, and could have been at great risk. Given this potential risk, the Philippine Institute of Volcanology and Seismology (PHIVOLCS) in early August 2001 advocated three actions. (1) An intentional breaching of the Maraunot Notch by the construction of a spillway or canal, by the Department of Public Works and Highways (DPWH). Early breaching would limit further rise of the lake and thus reduce the magnitude of potential flood. Also, breaching would be scheduled during good weather to eliminate the danger of overtopping at an unknown time and/or under typhoon/rainstorm conditions. (2) An information campaign in Botolan in order to educate and prepare residents for breaching. (3) Evacuation of people at risk, one day before the scheduled breaching. A spillway was excavated by as many

  19. Complex explosive volcanic activity on the Moon within Oppenheimer crater

    NASA Astrophysics Data System (ADS)

    Bennett, Kristen A.; Horgan, Briony H. N.; Gaddis, Lisa R.; Greenhagen, Benjamin T.; Allen, Carlton C.; Hayne, Paul O.; Bell, James F.; Paige, David A.

    2016-07-01

    Oppenheimer crater is a floor-fractured crater located within the South Pole-Aitken basin on the Moon, and exhibits more than a dozen localized pyroclastic deposits associated with the fractures. Localized pyroclastic volcanism on the Moon is thought to form as a result of intermittently explosive Vulcanian eruptions under low effusion rates, in contrast to the higher-effusion rate, Hawaiian-style fire fountaining inferred to form larger regional deposits. We use Lunar Reconnaissance Orbiter Camera images and Diviner Radiometer mid-infrared data, Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra, and Clementine orbiter Ultraviolet/visible camera images to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. Mineralogically, we find that the deposits are variable mixtures of orthopyroxene and minor clinopyroxene sourced from the crater floor, juvenile clinopyroxene, and juvenile iron-rich glass, and that the mineralogy of the pyroclastics varies both across the Oppenheimer deposits as a whole and within individual deposits. We observe similar variability in the inferred iron content of pyroclastic glasses, and note in particular that the northwest deposit, associated with Oppenheimer U crater, contains the most iron-rich volcanic glass thus far identified on the Moon, which could be a useful future resource. We propose that this variability in mineralogy indicates variability in eruption style, and that it cannot be explained by a simple Vulcanian eruption. A Vulcanian eruption should cause significant country rock to be incorporated into the pyroclastic deposit; however, large areas within many of the deposits exhibit spectra consistent with high abundances of juvenile phases and very little floor material. Thus, we propose that at least the most recent portion of these deposits must have erupted via a Strombolian or more continuous fire

  20. Water in the Oceanic Lithosphere: Salt Lake Crater Xenoliths, Oahu, Hawaii

    NASA Technical Reports Server (NTRS)

    Peslier, Anne H.; Bizimis, Michael

    2010-01-01

    Water can be present in nominally anhydrous minerals of peridotites in the form of hydrogen bonded to structural oxygen. Such water in the oceanic upper mantle could have a significant effect on its physical and chemical properties. However, the water content of the MORB source has been inferred indirectly from the compositions of basalts. Direct determinations on abyssal peridotites are scarce because they have been heavily hydrothermally altered. Here we present the first water analyses of minerals from spinel peridotite xenoliths of Salt Lake Crater, Oahu, Hawaii, which are exceptionally fresh. These peridotites are thought to represent fragments of the Pacific oceanic lithosphere that was refertilized by alkalic Hawaiian melts. A few have unradiogenic Os and radiogenic Hf isotopes and may be fragments of an ancient (2 Ga) depleted and recycled lithosphere. Water contents in olivine (Ol), orthopyroxene (Opx), and clinopyroxene (Cpx) were determined by FTIR spectrometry. Preliminary H_{2}O contents show ranges of 8-10 ppm for Ol, 151-277 ppm for Opx, and 337-603 ppm for Cpx. Reconstructed bulk rock H_{2}O contents range from 88-131 ppm overlapping estimates for the MORB source. Water contents between Ol minerals of the same xenolith are heterogeneous and individual OH infrared bands vary within a mineral with lower 3230 cm^{-1} and higher 3650-3400 cm^{-1} band heights from core to edge. This observation suggests disturbance of the hydrogen in Ol likely occurring during xenolith entrainment to the surface. Pyroxene water contents are higher than most water contents in pyroxenes from continental peridotite xenoliths and higher than those of abyssal peridotites. Cpx water contents decrease with increasing degree of depletion (e.g. increasing Fo in Ol and Cr# in spinel) consistent with an incompatible behavior of water. However Cpx water contents also show a positive correlation with LREE/HREE ratios and LREE concentrations consistent with refertilization. Opx water

  1. Deformation of the Wineglass Welded Tuff and the timing of caldera collapse at Crater Lake, Oregon

    USGS Publications Warehouse

    Kamata, H.; Suzuki-Kamata, K.; Bacon, C.R.

    1993-01-01

    Four types of deformation occur in the Wineglass Welded Tuff on the northeast caldera rim of Crater Lake: (a) vertical tension fractures; (b) ooze-outs of fiamme: (c) squeeze-outs of fiamme; and (d) horizontal pull-apart structures. The three types of plastic deformation (b-d) developed in the lower part of the Wineglass Welded Tuff where degree of welding and density are maximum. Deformation originated from concentric normal faulting and landsliding as the caldera collapsed. The degree of deformation of the Wineglass Welded Tuff increases toward the northeast part of the caldera, where plastic deformation occurred more easily because of a higher emplacement temperature probably due to proximity to the vent. The probable glass transition temperature of the Wineglass Welded Tuff suggests that its emplacement temperature was ???750??C where the tuff is densely welded. Calculation of the conductive cooling history of the Wineglass Welded Tuff and the preclimactic Cleetwood (lava) flow under assumptions of a initially isothermal sheet and uniform properties suggests that (a) caldera collapse occurred a maximum of 9 days after emplacement of the Wineglass Welded Tuff, and that (b) the period between effusion of the Cleetwood (lava) flow and onset of the climactic eruption was <100 years. If cooling is controlled more by precipitation during quiescent periods than by conduction, these intervals must be shorter than the calculated times. ?? 1993.

  2. Late Pleistocene granodiorite beneath Crater Lake caldera, Oregon, dated by ion microprobe

    USGS Publications Warehouse

    Bacon, C.R.; Persing, H.M.; Wooden, J.L.; Ireland, T.R.

    2000-01-01

    Variably melted granodiorite blocks ejected during the Holocene caldera-forming eruption of Mount Mazama were plucked from the walls of the climactic magma chamber ~15 km depth. Ion-microprobe U-Pb dating of zircons from two unmelted granodiorite blocks with SHRIMP RG (sensitive high-resolution ion microprobe-reverse geometry) gives a nominal 238U/206Pb age of 101+78-80 ka, or 174+89-115 ka when adjusted for an initial 230Th deficit. SHRIMP RG U-Th measurements on a subset of the zircons yield a 230Th/238U isochron age of 112 ?? 24 ka, considered to be the best estimate of the time of solidification of the pluton. These results suggest that the granodiorite is related to andesite and dacite of Mount Mazama and not to magmas of the climactic eruption. The unexposed granodiorite has an area of at least 28 km2. This young, shallow pluton was emplaced in virtually the same location where a similarly large magma body accumulated and powered violent explosive eruptions ~7700 yr ago, resulting in collapse of Crater Lake caldera.

  3. Evidence for Impact-induced Hydrothermal Alteration at the Lonar Crater, India, and Mistastin Lake, Canada

    NASA Technical Reports Server (NTRS)

    Newsom, H. E.; Hagerty, J. J.

    2003-01-01

    The 50,000 year old, 1.8km diameter Lonar crater is located in Maharashtra, India. This relatively small crater is of particular interest because of its unique morphological and mineralogical properties, which make it a valid analogue for similar craters on the surface of Mars. We show that even in this relatively small crater, substantial hydrothermal alteration of shocked breccias in the floor of the crater has occurred, probably due to the thermal effects of the impact event. The 38 my old, 28 km diameter, Mistastin crater contains an 80 m thick impact melt sheet. We have also documented the presence of alteration phases in the material from this larger crater.

  4. Valley formation by groundwater seepage, pressurized groundwater outbursts and crater-lake overflow in flume experiments with implications for Mars

    NASA Astrophysics Data System (ADS)

    Marra, Wouter A.; Braat, Lisanne; Baar, Anne W.; Kleinhans, Maarten G.

    2014-04-01

    Remains of fluvial valleys on Mars reveal the former presence of water on the surface. However, the source of water and the hydrological setting is not always clear, especially in types of valleys that are rare on Earth and where we have limited knowledge of the processes involved. We investigated three hydrological scenarios for valley formation on Mars: hydrostatic groundwater seepage, release of pressurized groundwater and crater-lake overflow. Using physical modeling in laboratory experiments and numerical hydrological modeling we quantitatively studied the morphological development and processes involved in channel formation that result from these different sources of water in unconsolidated sediment. Our results show that valleys emerging from seeping groundwater by headward erosion form relatively slowly as fluvial transport takes place in a channel much smaller than the valley. Pressurized groundwater release forms a characteristic source area at the channel head by fluidization processes. This head consist of a pit in case of superlithostatic pressure and may feature small radial channels and collapse features. Valleys emerging from a crater-lake overflow event develop quickly in a run-away process of rim erosion and discharge increase. The valley head at the crater outflow point has a converging fan shape, and the rapid incision of the rim leaves terraces and collapse features. Morphological elements observed in the experiments can help in identifying the formative processes on Mars, when considerations of experimental scaling and lithological characteristics of the martian surface are taken into account. These morphological features might reveal the associated hydrological settings and formative timescales of a valley. An estimate of formative timescale from sediment transport is best based on the final channel dimensions for groundwater seepage valleys and on the valley dimensions for pressurized groundwater release and crater-lake overflow valleys. Our

  5. Composition and heterogeneity of anorthositic impact melt at Mistastin Lake crater, Labrador

    NASA Astrophysics Data System (ADS)

    Marion, Cassandra L.; Sylvester, Paul J.

    2010-03-01

    Anorthositic impact melt rocks, their target rocks (principally anorthosite, mangerite, granodiorite) and zircon clasts from the ˜36-Ma-old, 28-km-wide Mistastin Lake crater of northern Labrador (55°53'N; 63°18'W) have been examined in order to evaluate the scale and origin of compositional heterogeneities in impact melts produced in craters of moderate size. In particular we assess whether and, if so, how the initial composition of the impact melt was modified as it entrained mineral clasts derived from the underlying rocks over which it flowed when it moved away from the shock-induced, central melting zone. A secondary goal was to determine if zircon clasts in the impact melts are present in the proportions of their target rock sources and/or the substrate lithologies over which they flowed. Chemical compositions of bulk samples of 33 melt rocks and 14 target rocks were measured by XRF and SN-ICPMS. Matrix compositions of nine samples of impact melt rocks were determined by EPMA and LA-ICPMS. Zircon grains from four samples of target rock and zircon clasts from three samples of impact melt rock were measured for multi-element composition, U-Pb age and Hf-isotopic composition by LA-(MC)-ICPMS. The data reveal compositional heterogeneities in the impact melts on the scales of both bulk samples and matrices. Bulk samples can be divided into compositions with high and low concentrations of high-field-strength elements (HFSE; Ti, Zr, Nb) and Fe, Ba, Ce and Y. High HFSE-type melt rocks formed when impact melt entrained large quantities of clasts from mangerite, which is rich in HFSE. Matrix compositions of bulk samples do not show the HFSE distinction but are affected by the introduction of low-temperature melts from the clasts to form dispersed, micron-scale silica-rich heterogeneities. The best estimate of sources of the initial impact melt is ˜73% anorthosite, ˜7% mangerite and ˜20% granodiorite, based on least-squares modeling of major-element compositions of

  6. Multispecies Outcomes of Sympatric Speciation after Admixture with the Source Population in Two Radiations of Nicaraguan Crater Lake Cichlids.

    PubMed

    Kautt, Andreas F; Machado-Schiaffino, Gonzalo; Meyer, Axel

    2016-06-01

    The formation of species in the absence of geographic barriers (i.e. sympatric speciation) remains one of the most controversial topics in evolutionary biology. While theoretical models have shown that this most extreme case of primary divergence-with-gene-flow is possible, only a handful of accepted empirical examples exist. And even for the most convincing examples uncertainties remain; complex histories of isolation and secondary contact can make species falsely appear to have originated by sympatric speciation. This alternative scenario is notoriously difficult to rule out. Midas cichlids inhabiting small and remote crater lakes in Nicaragua are traditionally considered to be one of the best examples of sympatric speciation and lend themselves to test the different evolutionary scenarios that could lead to apparent sympatric speciation since the system is relatively small and the source populations known. Here we reconstruct the evolutionary history of two small-scale radiations of Midas cichlids inhabiting crater lakes Apoyo and Xiloá through a comprehensive genomic data set. We find no signs of differential admixture of any of the sympatric species in the respective radiations. Together with coalescent simulations of different demographic models our results support a scenario of speciation that was initiated in sympatry and does not result from secondary contact of already partly diverged populations. Furthermore, several species seem to have diverged simultaneously, making Midas cichlids an empirical example of multispecies outcomes of sympatric speciation. Importantly, however, the demographic models strongly support an admixture event from the source population into both crater lakes shortly before the onset of the radiations within the lakes. This opens the possibility that the formation of reproductive barriers involved in sympatric speciation was facilitated by genetic variants that evolved in a period of isolation between the initial founding

  7. Multispecies Outcomes of Sympatric Speciation after Admixture with the Source Population in Two Radiations of Nicaraguan Crater Lake Cichlids

    PubMed Central

    Kautt, Andreas F.; Machado-Schiaffino, Gonzalo; Meyer, Axel

    2016-01-01

    The formation of species in the absence of geographic barriers (i.e. sympatric speciation) remains one of the most controversial topics in evolutionary biology. While theoretical models have shown that this most extreme case of primary divergence-with-gene-flow is possible, only a handful of accepted empirical examples exist. And even for the most convincing examples uncertainties remain; complex histories of isolation and secondary contact can make species falsely appear to have originated by sympatric speciation. This alternative scenario is notoriously difficult to rule out. Midas cichlids inhabiting small and remote crater lakes in Nicaragua are traditionally considered to be one of the best examples of sympatric speciation and lend themselves to test the different evolutionary scenarios that could lead to apparent sympatric speciation since the system is relatively small and the source populations known. Here we reconstruct the evolutionary history of two small-scale radiations of Midas cichlids inhabiting crater lakes Apoyo and Xiloá through a comprehensive genomic data set. We find no signs of differential admixture of any of the sympatric species in the respective radiations. Together with coalescent simulations of different demographic models our results support a scenario of speciation that was initiated in sympatry and does not result from secondary contact of already partly diverged populations. Furthermore, several species seem to have diverged simultaneously, making Midas cichlids an empirical example of multispecies outcomes of sympatric speciation. Importantly, however, the demographic models strongly support an admixture event from the source population into both crater lakes shortly before the onset of the radiations within the lakes. This opens the possibility that the formation of reproductive barriers involved in sympatric speciation was facilitated by genetic variants that evolved in a period of isolation between the initial founding

  8. Origin and speciation of haplochromine fishes in East African crater lakes investigated by the analysis of their mtDNA, Mhc genes, and SINEs.

    PubMed

    Sato, Akie; Takezaki, Naoko; Tichy, Herbert; Figueroa, Felipe; Mayer, Werner E; Klein, Jan

    2003-09-01

    The Western Branch of the East African Great Rift Valley is pocketed with craters of extinct or dormant volcanoes. Many of the craters are filled with water, and the lakes are inhabited by fishes. The objective of the present study was to determine the amount and nature of genetic variation in haplochromine fishes inhabiting two of these crater lakes, Lake Lutoto and Lake Nshere, and to use this information to infer the origin and history of the two populations. To this end, sequences of mitochondrial (mt) DNA control region, exon 2 of major histocompatibility complex (Mhc) class II B genes, and short interspersed elements (SINEs) were analyzed. The results indicate that the Lake Nshere and Lake Lutoto fishes originated from different but related large founding populations derived from the Kazinga Channel, which connects Lake Edward and Lake George. Some of the genetic polymorphism that existed in the ancestral populations was lost in the populations of the two lakes. The polymorphism that has been retained has persisted for some 50000 generations (years). During this time, new mutations arose and became fixed in each of the two populations in the mtDNA, giving rise to sets of diagnostic substitutions. Each population evolved in isolation after the colonization of the lakes less than 50000 years ago. There appears to be no population structure within the crater lake fishes, and their present effective population sizes are in the order of 104 to 105 individuals. Comparisons with the endemic haplochromine species of Lake Victoria reveal interesting parallels, as well as differences, which may help to understand the nature of the speciation process. PMID:12777512

  9. Late Pleistocene granodiorite source for recycled zircon and phenocrysts in rhyodacite lava at Crater Lake, Oregon

    USGS Publications Warehouse

    Bacon, C.R.; Lowenstern, J. B.

    2005-01-01

    Rhyodacite tephra and three lavas erupted ???27 ka, interpreted to be early leaks from the climactic magma chamber of Mount Mazama, contain ubiquitous resorbed crystals (antecrysts) that were recycled from young granodiorite and related plutonic rocks of the same magmatic system. The shallow composite pluton is represented by blocks ejected in the 7.7-ka climactic eruption that formed Crater Lake caldera. Plagioclase crystals in both rhyodacite and granodiorites commonly have cores with crystallographically oriented Fe-oxide needles exsolved at subsolidus conditions. At least 80% of plagioclase crystals in the rhyodacite are antecrysts derived from plutonic rocks. Other crystals in the rhyodacite, notably zircon, also were recycled. SIMS 238U- 230Th dating indicates that zircons in 4 granodiorite blocks crystallized at various times between ???20 ka and ???300 ka with concentrations of analyses near 50-70, ???110, and ???200 ka that correspond to periods of dacitic volcanism dated by K- Ar. U-Th ages of zircon from a rhyodacite sample yield similar results. No analyzed zircons from the granodiorite or rhyodacite are pre-Quaternary. Zircon minimum ages in blocks from different locations around the caldera reflect ages of nearby volcanic vents and may map the distribution of intrusions within a composite pluton. Survival of zircon in zircon-undersaturated hydrous magma and of Fe-oxide needles in plagioclase suggests that little time elapsed from entrainment of antecrysts to the ???27-ka eruption of the rhyodacite. The ???27-ka rhyodacite is an example of young silicic magma that preserved unstable antecrysts from a known source early during growth of a large high-level magma chamber. In contrast, the voluminous 7.7-ka climactic rhyodacite pumice is virtually lacking in zircon, indicating dissolution of any granodioritic debris in the intervening period. Mineralogical evidence of assimilation may be destroyed in hot, vigorously growing silicic magma bodies such as

  10. Seasonal nutrient and plankton dynamics in a physical-biological model of Crater Lake

    USGS Publications Warehouse

    Fennel, K.; Collier, R.; Larson, G.; Crawford, G.; Boss, E.

    2007-01-01

    A coupled 1D physical-biological model of Crater Lake is presented. The model simulates the seasonal evolution of two functional phytoplankton groups, total chlorophyll, and zooplankton in good quantitative agreement with observations from a 10-year monitoring study. During the stratified period in summer and early fall the model displays a marked vertical structure: the phytoplankton biomass of the functional group 1, which represents diatoms and dinoflagellates, has its highest concentration in the upper 40 m; the phytoplankton biomass of group 2, which represents chlorophyta, chrysophyta, cryptomonads and cyanobacteria, has its highest concentrations between 50 and 80 m, and phytoplankton chlorophyll has its maximum at 120 m depth. A similar vertical structure is a reoccurring feature in the available data. In the model the key process allowing a vertical separation between biomass and chlorophyll is photoacclimation. Vertical light attenuation (i.e., water clarity) and the physiological ability of phytoplankton to increase their cellular chlorophyll-to-biomass ratio are ultimately determining the location of the chlorophyll maximum. The location of the particle maxima on the other hand is determined by the balance between growth and losses and occurs where growth and losses equal. The vertical particle flux simulated by our model agrees well with flux measurements from a sediment trap. This motivated us to revisit a previously published study by Dymond et al. (1996). Dymond et al. used a box model to estimate the vertical particle flux and found a discrepancy by a factor 2.5-10 between their model-derived flux and measured fluxes from a sediment trap. Their box model neglected the exchange flux of dissolved and suspended organic matter, which, as our model and available data suggests is significant for the vertical exchange of nitrogen. Adjustment of Dymond et al.'s assumptions to account for dissolved and suspended nitrogen yields a flux estimate that is

  11. Os and U-Th isotope signatures of arc magmatism near Mount Mazama, Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Ankney, Meagan E.; Shirey, Steven B.; Hart, Garret L.; Bacon, Charles R.; Johnson, Clark M.

    2016-03-01

    Interaction of mantle melts with the continental crust can have significant effects on the composition of the resulting melts as well as on the crust itself, and tracing this interaction is key to our understanding of arc magmatism. Lava flows and pyroclastic deposits erupted from ∼50 to 7.7 ka at Mt. Mazama (Crater Lake, Oregon) were analyzed for their Re/Os and U-Th isotopic compositions. Mafic lavas from monogenetic vents around Mt. Mazama that erupted during the buildup to its climactic eruption have lower 187Os/188Os ratios (0.1394 to 0.1956) and high 230Th excess ((230Th/238U)0 of 1.180 to 1.302), whereas dacites and rhyodacites tend to have higher 187Os/188Os ratios (0.2292 to 0.2788) and significant 238U excess ((230Th/238U)0 of 0.975 to 0.989). The less radiogenic Os isotope compositions of the mafic lavas can be modeled by assimilation of young (∼2.5 to 7 Ma), mafic lower crust that was modified during regional extension, whereas the more radiogenic Os isotope compositions of the dacites and rhyodacites can be attributed to assimilation of older (∼10 to 16 Ma), mid to upper crust that acquired its composition during an earlier period of Cascade magmatism. Production of Th excesses in the lower crust requires very young garnet formation accompanying dehydration melting in the lower crust at less than a few 100 ka by heat from recent basaltic magma injection. The results from this study suggest that the combination of Os and Th isotopes may be used to provide insights into the timescales of evolution of the continental crust in arc settings, as well as the influence of the crust on erupted magmas, and suggest a link between the age and composition of the lower and upper crust to regional tectonic extension and/or earlier Cascade magmatism.

  12. Pseudorhodobacter sinensis sp. nov. and Pseudorhodobacter aquaticus sp. nov., isolated from crater lakes.

    PubMed

    Li, Ai-Hua; Liu, Hong-Can; Hou, Wei-Guo; Zhou, Yu-Guang

    2016-08-01

    Three Gram-stain negative, aerobic, non-motile, rod-shaped bacterial strains, Y1R2-4T, Y3R2-3 and DC2N1-10T, isolated from two crater lakes of the Daxinganling Mountains, northern China, were studied to determine their taxonomic position. They grew at 4-30 °C (optimally at 20-25 °C), at pH 6.0-7.5 (optimally at pH 7.0) and in the presence of 0-0.5 % (w/v) NaCl. On the basis of 16S rRNA gene sequence analysis, these strains showed 95.3-96.6 % similarity to members of the genus Pseudorhodobacter, including Pseudorhodobacter ferrugineus DSM 5888T, Pseudorhodobacter wandonensis WT-MW11T, Pseudorhodobacter antarcticus ZS3-33T and Pseudorhodobacter aquimaris HDW-19T. All strains contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The main polar lipids for strains Y1R2-4T and Y3R2-3 were phosphatidylglycerol, phosphatidylcholine, one unidentified aminophospholipid, one unidentified aminolipid, three unidentified phospholipids and two unidentified lipids, and those for strain DC2N1-10T were phosphatidylglycerol, phosphatidylcholine, one unidentified aminophospholipid, one unidentified aminolipid, one unidentified phospholipid and several unidentified lipids. The DNA G+C contents of strains Y1R2-4T, Y3R2-3 and DC2N1-10T were 61.9, 61.0 and 60.0 mol%, respectively. In addition, strain Y1R2-4T shared less than 50 % DNA-DNA relatedness to strain DC2N1-10T. Based on these differences in genetic, physiological and chemotaxonomic properties, strains Y1R2-4T, Y3R2-3 and DC2N1-10T were considered to represent two novel species of the genus Pseudorhodobacter, for which the names Pseudorhodobacter sinensis sp. nov. (type strain Y1R2-4T=CGMCC1.14435T=KCTC 52039T) and Pseudorhodobacter aquaticus sp. nov. (type strain DC2N1-10T=CGMCC1.14433T=KCTC 52040T) are proposed. PMID:27045957

  13. Structure and physical characteristics of pumice from the climactic eruption of Mount Mazama (Crater Lake), Oregon

    USGS Publications Warehouse

    Klug, C.; Cashman, K.; Bacon, C.

    2002-01-01

    The vesicularity, permeability, and structure of pumice clasts provide insight into conditions of vesiculation and fragmentation during Plinian fall and pyroclastic flow-producing phases of the ???7,700 cal. year B.P. climactic eruption of Mount Mazama (Crater Lake), Oregon. We show that bulk properties (vesicularity and permeability) can be correlated with internal textures and that the clast structure can be related to inferred changes in eruption conditions. The vesicularity of all pumice clasts is 75-88%, with >90% interconnected pore volume. However, pumice clasts from the Plinian fall deposits exhibit a wider vesicularity range and higher volume percentage of interconnected vesicles than do clasts from pyroclastic-flow deposits. Pumice permeabilities also differ between the two clast types, with pumice from the fall deposit having higher minimum permeabilities (???5??10-13 m2) and a narrower permeability range (5-50??10-13 m2) than clasts from pyroclastic-flow deposits (0.2-330??10-13 m2). The observed permeability can be modeled to estimate average vesicle aperture radii of 1-5 ??m for the fall deposit clasts and 0.25-1 ??m for clasts from the pyroclastic flows. High vesicle number densities (???109 cm-3) in all clasts suggest that bubble nucleation occured rapidly and at high supersaturations. Post-nucleation modifications to bubble populations include both bubble growth and coalescence. A single stage of bubble nucleation and growth can account for 35-60% of the vesicle population in clasts from the fall deposits, and 65-80% in pumice from pyroclastic flows. Large vesicles form a separate population which defines a power law distribution with fractal dimension D=3.3 (range 3.0-3.5). The large D.value, coupled with textural evidence, suggests that the large vesicles formed primarily by coalescence. When viewed together, the bulk properties (vesicularity, permeability) and textural characteristics of all clasts indicate rapid bubble nucleation followed by

  14. Hydrothermal activity recorded in post Noachian-aged impact craters on Mars

    NASA Astrophysics Data System (ADS)

    Turner, Stuart M. R.; Bridges, John C.; Grebby, Stephen; Ehlmann, Bethany L.

    2016-04-01

    Hydrothermal systems have previously been reported in ancient Noachian and Hesperian-aged craters on Mars using CRISM but not in Amazonian-aged impact craters. However, the nakhlite meteorites do provide evidence of Amazonian hydrothermal activity. This study uses CRISM data of 144 impact craters of ≥7 km diameter and 14 smaller craters (3-7 km diameter) within terrain mapped as Amazonian to search for minerals that may have formed as a result of impact-induced hydrothermal alteration or show excavation of ancient altered crust. No evidence indicating the presence of hydrated minerals was found in the 3-7 km impact craters. Hydrated minerals were identified in three complex impact craters, located at 52.42°N, 39.86°E in the Ismenius Lacus quadrangle, at 8.93°N, 141.28°E in Elysium, and within the previously studied Stokes crater. These three craters have diameters 20 km, 62 km, and 51 km. The locations of the hydrated mineral outcrops and their associated morphology indicate that two of these three impact craters—the unnamed Ismenius Lacus Crater and Stokes Crater—possibly hosted impact-induced hydrothermal systems, as they contain alteration assemblages on their central uplifts that are not apparent in their ejecta. Chlorite and Fe serpentine are identified within alluvial fans in the central uplift and rim of the Ismenius Lacus crater, whereas Stokes crater contains a host of Fe/Mg/Al phyllosilicates. However, excavation origin cannot be precluded. Our work suggests that impact-induced hydrothermalism was rare in the Amazonian and/or that impact-induced hydrothermal alteration was not sufficiently pervasive or spatially widespread for detection by CRISM.

  15. Distribution of Glycerol Diakyl Glycerol Tetraethers in Surface Soil and Crater Lake Sediments from Mount Kenya, East Africa

    NASA Astrophysics Data System (ADS)

    Omuombo, C.; Huguet, A.; Olago, D.; Williamson, D.

    2013-12-01

    Glycerol diakyl glycerol tetraethers (GDGTs), a palaeoclimate proxy based on the relative abundance of lipids produced by archaea and bacteria, is gaining wide acceptance for the determination of past temperature and pH conditions. This study looks at the spatial distribution and abundance of GDGTs in soil and sediment samples along an altitudinal transect from 3 crater lakes of Mt. Kenya (Lake Nkunga, Sacred Lake and Lake Rutundu) ranging in elevation from 1700m - 3080m above sea level. GDGTs were extracted with solvents and then analysed using high performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS). Mean annual air temperature and pH were estimated based on the relative abundance of the different branched GDGTs, i.e. on the MBT (Methylation index of Branched Tetraethers) and CBT (Cyclization ratio of Branched Tetraethers) indices. Substantial amount of GDGTs were detected in both soil and sediment samples. In addition, branched GDGT distribution was observed to vary with altitude. These results highlight the importance of quantifying the branched GDGTs to understand the environmental parameters controlling the distribution of these lipids. The MBT/CBT proxy is a promising tool to infer palaeotemperatures and characterize the climate events of the past millennia in equatorial east Africa.

  16. Evidence of Non-Impact Cratering Origin of Imilchil (Morocco) Lakes (Isli and Tislit)

    NASA Astrophysics Data System (ADS)

    Chaabout, S.; Chennaoui Aoudjehane, H.; Reimold, W. U.; Aboulahris, M.; Aoudjehane, M.

    2013-08-01

    Isli and Tislit lakes (High Atlas Mountains, Morocco) were recently proposed as impact structures, related to the Agoudal iron meteorite found about twenty km from the lakes. Our study did not provide any evidence for such an origin.

  17. Compositional evolution of the zoned calcalkaline magma chamber of Mount Mazama, Crater Lake, Oregon

    USGS Publications Warehouse

    Bacon, C.R.; Druitt, T.H.

    1988-01-01

    The climactic eruption of Mount Mazama has long been recognized as a classic example of rapid eruption of a substantial fraction of a zoned magma body. Increased knowledge of eruptive history and new chemical analyses of ???350 wholerock and glass samples of the climactic ejecta, preclimactic rhyodacite flows and their inclusions, postcaldera lavas, and lavas of nearby monogenetic vents are used here to infer processes of chemical evolution of this late Pleistocene - Holocene magmatic system. The 6845??50 BP climactic eruption vented ???50 km3 of magma to form: (1) rhyodacite fall deposit; (2) welded rhyodacite ignimbrite; and (3) lithic breccia and zoned ignimbrite, these during collapse of Crater Lake caldera. Climactic ejecta were dominantly homogeneous rhyodacite (70.4??0.3% SiO2), followed by subordinate andesite and cumulate scoriae (48-61% SiO2). The gap in wholerock composition reflects mainly a step in crystal content because glass compositions are virtually continuous. Two types of scoriae are distinguished by different LREE, Rb, Th, and Zr, but principally by a twofold contrast in Sr content: High-Sr (HSr) and low-Sr (LSr) scoriae. HSr scoriae were erupted first. Trace element abundances indicate that HSr and LSr scoriae had different calcalkaline andesite parents; basalt was parental to some mafic cumulate scoriae. Parental magma compositions reconstructed from scoria wholerock and glass data are similar to those of inclusions in preclimactic rhyodacites and of aphyric lavas of nearby monogenetic vents. Preclimactic rhyodacite flows and their magmatic inclusions give insight into evolution of the climactic chamber. Evolved rhyodacite flows containing LSr andesite inclusions were emplaced between ???30000 and ???25000 BP. At 7015??45 BP, the Llao Rock vent produced a zoned rhyodacite pumice fall, then rhyodacite lava with HSr andesite inclusions. The Cleetwood rhyodacite flow, emplaced immediately before the climactic eruption and compositionally

  18. A viable microbial community in a subglacial volcanic crater lake, Iceland.

    PubMed

    Gaidos, Eric; Lanoil, Brian; Thorsteinsson, Thorsteinn; Graham, Andrew; Skidmore, Mark; Han, Suk-Kyun; Rust, Terri; Popp, Brian

    2004-01-01

    We describe a viable microbial community in a subglacial lake within the Grímsvötn volcanic caldera, Iceland. We used a hot water drill to penetrate the 300-m ice shelf and retrieved lake water and volcanic tephra sediments. We also acquired samples of borehole water before and after penetration to the lake, overlying glacial ice and snow, and water from a nearby subaerial geothermal lake for comparative analyses. Lake water is at the freezing point and fresh (total dissolved solids = 260 mg L(-1)). Detectable numbers of cells were found in samples of the lake water column and tephra sediments: 2 x 10(4) ml(-1) and 4 x 10(7) g(-1), respectively. Plate counts document abundant cold-adapted cultivable organisms in the lake water, but not in the borehole (before penetration) or glacial ice. Denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments amplified from genomic DNA extracted from Grímsvötn samples indicates that the lake community is distinct from the assemblages of organisms in borehole water (before penetration) and the overlying ice and snow. Sequencing of selected DGGE bands revealed that many sequences are highly similar to known psychrophilic organisms or cloned DNA from other cold environments. Significant uptake of 14C-labeled bicarbonate occurred in dark, low-temperature incubations of lake water samples, indicating the presence of autotrophs. Acetylene reduction assays under similar incubation conditions showed no significant nitrogen fixation potential by lake water samples. This may be a consequence of the inhibition of diazotrophy by nitrogen in the lake. PMID:15383238

  19. Construction and interpretation of a digital inertia image. [of Pisgah Crater and Lavic Lake in Southern California

    NASA Technical Reports Server (NTRS)

    Gillespie, A. R.; Kahle, A. B.

    1977-01-01

    An image representing the thermal inertia in the vicinity of Pisgah Crater and Lavic Lake in Southern California has been generated from visible, near IR, and thermal images taken from aircraft. Construction of the thermal inertia image required radiometric calibration and geometric rectification of the acquired images as well as registration to a topographic map. The Kahle thermal model used in the construction of the thermal inertia image requires specification of albedo, topographic slope and slope azimuth, diurnal temperature range and local meteorological conditions. Albedo information was derived from the visible image; digital topographic information was computed from digitized stereo aerial photographs; and thermal ranges were calculated by subtracting the predawn from the afternoon thermal image data. Our computed values of thermal inertia were in close agreement with published values for similar surface materials. Thermal inertia provides complementary information to conventional images of reflected solar radiation for use in lithologic mapping.

  20. Isotope hydrology of El Chichón volcano-hydrothermal system; a coupled system of crater lake and hot springs

    NASA Astrophysics Data System (ADS)

    Peiffer, L.; Taran, Y.; Rouwet, D.

    2010-12-01

    The catastrophic 1982 eruption of El Chichón (>1.5 km3 of erupted material) opened the upper hundred meters of the existing volcano-hydrothermal system. In the new formed 200m-deep crater a large shallow crater lake and numerous hot springs were formed. The lake existence and its salinity depend on the precipitation (~4000 mm/y) as well as a group of geyser-like neutral saline springs (source of Cl and SO4) and hydrothermal steam vents discharging into the lake (source of SO4). The chemistry of these “Soap Pool” (SP) springs evolved from >13,000 ppm of Cl in 1995 to ~2000-3000 ppm of Cl in 2006. Since 2006, this Cl-concentration in SP waters is constant. Similar concentrations of Cl are observed in most flank hot springs located at altitudes of ~ 600 m asl, 2-3 km from the crater. Therefore, it can be suggested that the flank springs, crater lake and crater hot springs are manifestations of the upper, relatively shallow volcano-hydrothermal system developed beneath the crater in the volcano edifice. Water isotopic composition of all types of thermal and fresh waters including fumarolic steam condensates (>100 samples collected in 1995-2010) allow to classify and distinguish different processes of shallow mixing, boiling, evaporation and water-rock isotope exchange. All spring waters from the upper system have meteoric origin, with the isotopic composition plotting close to the meteoric water line. Crater waters are strongly evolved due to shallow boiling and loss of steam. Isotopic composition of water from the lower, deep hydrothermal system is characterized by a significant positive oxygen isotopic shift and a strong Cl-d18O linear correlation. Waters from numerous cold springs that drain pyroclastic deposits demonstrate a clear negative oxygen shift. Some problems related to water isotopic composition are still remain unresolved: (1) we cannot find any traces of the infiltrated isotopically heavy lake waters, i.e., the seepage from the lake at the volcano

  1. A detailed geologic characterization of Eberswalde crater, Mars

    NASA Astrophysics Data System (ADS)

    Rice, M. S.; BellI, J. F., III; Gupta, S.; Warner, N. H.; Goddard, K.; Anderson, R. B.

    Background: Eberswalde crater, selected as one of four finalist landing sites for the Mars Science Laboratory mission, is best known for the spectacularly preserved, inverted, fan-shaped deposit along its western margin. This feature has been interpreted as a lacustrine delta, although the timing and duration of an Eberswalde crater lake is poorly understood. The aim of this study is to place more broadly observed fluvio-lacustrine activity throughout the crater's floor within the larger context of Eberswalde's geologic history, and to infer the sequence of deposition and erosion of the observed stratigraphic and geomorphic units. Method: We have identified and mapped stratigraphic and geomorphic units within all of Eberswalde crater using orbital imagery from the HiRISE, MOC and CTX cameras, and we have calculated crater statistics to infer the relative ages of crater floor materials. Using topographic datasets derived from HiRISE, CTX and MOLA, we determine the unit associations, successions, and geometries and develop a model for the depositional and erosional history within the crater. Conclusion: We have produced maps of ten stratigraphic and seven geomorphic units identified within Eberswalde crater. Our observations of the stratigraphy, geomorphology, topography and crater densities imply a complex relationship between deposition and exhumation within Eberswalde crater, and we infer the following sequence of major events: (1) Eberswalde crater forms in the Noachian (> 3.6 Ga); (2) Holden crater forms southwest of Eberswalde crater in the late Noachian to Early Hesperian, and its associated ejecta blanket covers the floor of Eberswalde crater and heavily modifies the southern rim; (3) Extensive faulting from regional stresses creates the first-order topography within the crater, and vein-like features form in some units from fracturing, fluid circulation, and cementation; (4) Valley features are carved in the crater walls as water flows into the crater

  2. Crater Lakes on Mars: Development of Quantitative Thermal and Geomorphic Models

    NASA Technical Reports Server (NTRS)

    Barnhart, C. J.; Tulaczyk, S.; Asphaug, E.; Kraal, E. R.; Moore, J.

    2005-01-01

    Impact craters on Mars have served as catchments for channel-eroding surface fluids, and hundreds of examples of candidate paleolakes are documented [1,2] (see Figure 1). Because these features show similarity to terrestrial shorelines, wave action has been hypothesized as the geomorphic agent responsible for the generation of these features [3]. Recent efforts have examined the potential for shoreline formation by wind-driven waves, in order to turn an important but controversial idea into a quantitative, falsifiable hypothesis. These studies have concluded that significant wave-action shorelines are unlikely to have formed commonly within craters on Mars, barring Earth-like weather for approx.1000 years [4,5,6].

  3. Impact-generated Hydrothermal Activity at the Chicxulub Crater

    NASA Astrophysics Data System (ADS)

    Kring, D. A.; Zurcher, L.; Abramov, O.

    2007-05-01

    Borehole samples recovered from PEMEX exploration boreholes and an ICDP scientific borehole indicate the Chicxulub impact event generated hydrothermal alteration throughout a large volume of the Maya Block beneath the crater floor and extending across the bulk of the ~180 km diameter crater. The first indications of hydrothermal alteration were observed in the crater discovery samples from the Yucatan-6 borehole and manifest itself in the form of anhydrite and quartz veins. Continuous core from the Yaxcopoil-1 borehole reveal a more complex and temporally extensive alteration sequence: following a brief period at high temperatures, impact- melt-bearing polymict breccias and a thin, underlying unit of impact melt were subjected to metasomatism, producing alkali feldspar, sphene, apatite, and magnetite. As the system continued to cool, smectite-series phyllosilicates appeared. A saline solution was involved. Stable isotopes suggest the fluid was dominated by a basinal brine created mostly from existing groundwater of the Yucatan Peninsula, although contributions from down-welling water also occurred in some parts of the system. Numerical modeling of the hydrothermal system suggests circulation occurred for 1.5 to 2.3 Myr, depending on the permeability of the system. Our understanding of the hydrothermal system, however, is still crude. Additional core recovery projects, particularly into the central melt sheet, are needed to better evaluate the extent and duration of hydrothermal alteration.

  4. Pyroclastic activity at home plate in Gusev crater, Mars

    USGS Publications Warehouse

    Squyres, S. W.; Aharonson, O.; Clark, B. C.; Cohen, B. A.; Crumpler, L.; de Souza, P.A.; Farrand, W. H.; Gellert, Ralf; Grant, J.; Grotzinger, J.P.; Haldemann, A.F.C.; Johnson, J. R.; Klingelhofer, G.; Lewis, K.W.; Li, R.; McCoy, T.; McEwen, A.S.; McSween, H.Y.; Ming, D. W.; Moore, Johnnie N.; Morris, R.V.; Parker, T.J.; Rice, J. W., Jr.; Ruff, S.; Schmidt, M.; Schroder, C.; Soderblom, L.A.; Yen, A.

    2007-01-01

    Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarse-grained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, whereas the upper unit may represent eolian reworking of the same pyroclastic materials.

  5. Pyroclastic Activity at Home Plate in Gusev Crater, Mars

    NASA Technical Reports Server (NTRS)

    Squyres, S. W.; Aharonson, O.; Clark, B. S.; Cohen, B.; Crumpler, L.; deSouza, P. A.; Farrand, W. H.; Gellert, R.; Grant, J.; Grotzinger, J. P.; Haldemann, A. F. C.; Johnson, J. R.; Klingelhoefer, G.; Lewis, K. W.; Li, R.; McCoy, T.; McEwen, A. S.; McSween, H. Y.; Ming, D. W.; Moore, J. M.; Morris, R. V.; Parker. T. J.; Rice, J. W., Jr.; Ruff, S.; Schmidt, M.

    2007-01-01

    Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarse-grained lower unit is overlain by a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic origin over an impact origin. The lower unit likely represents accumulation of pyroclastic materials, while the upper unit may represent eolian reworking of the same pyroclastic materials.

  6. Present-day aeolian activity in Herschel Crater, Mars

    NASA Astrophysics Data System (ADS)

    Cardinale, Marco; Silvestro, Simone; Vaz, David A.; Michaels, Timothy; Bourke, Mary C.; Komatsu, Goro; Marinangeli, Lucia

    2016-02-01

    In this report, we show evidence for ripple and dune migration in Herschel Crater on Mars. We estimate an average dune migration of 0.8 m and a minimum ripple migration of 1.1 m in a time span of 3.7 Earth-years. These dunes and ripples are mainly shaped by prevailing winds coming from the north, however we also report the presence of secondary winds which elongate the barchans' horns. Such a complex wind scenario is likely caused by the influence of winds blowing off the western crater rim as suggested by the Mars Regional Atmospheric Modeling System (MRAMS), an atmospheric mesoscale model. A multi-directional wind regime at the local scale is also supported by the observed bimodal distribution of the ripple trends. For the first time, a survey integrating the assessment of dune and ripple migration is presented, showing how dune topography can influence the migration patterns of ripples and how underlying topography appears to control the rates of dune migration.

  7. The Origin and Consequences of Steep-Sided Crater Lakes on Titan

    NASA Astrophysics Data System (ADS)

    Mitchell, Karl L.; Radebaugh, J.; Wood, C. A.; Lopes, R. M.; Lorenz, R. D.; Lunine, J. I.; Stofan, E. R.; Stiles, B. W.; Hensley, S.; Wall, S. D.; Cassini RADAR Team

    2006-09-01

    Cassini radar imagery obtained during the 22nd July 2006 (T16) Titan fly-by reveals the presence of lakes at >70° N (Wall et al., this volume). Several are in relatively steep-sided depressions, contrasting with other lakes in this region that exhibit no pronounced topography at this scale. We postulate based on the arguments in Wood et al. (this volume) that these depressions existed prior to being filled with fluids, and find that a volcanic origin, rather than chemical dissolution or impact, is most likely. A caldera is the preferred interpretation, on the basis of geomorphology, scale, and the lack of need to introduce novel chemical processes. Despite plentiful lakes in this region, there appear to be relatively few fluvial channels supplying them in contrast with other regions. We suggest that: (1) unlike at lower latitudes, precipitation is dominated by gentle rain, possibly ethane-rich, which would fill lakes gradually without high flow rates characteristic of storms that carve broad river channels; and/or (2) the crust is porous, accommodating sub-surface flow in a manner akin to terrestrial groundwater systems, in which case we might expect lake surfaces to follow an equipotential surface, which should be possible to test with stereo data following future fly-bys. The presence of calderas here, and in the Ta scene, lends credence to the use of terrestrial analogs for volcanic processes on Titan. The implication is that magma stalls at buoyancy/density traps in the upper crust to form magma chambers. If residence times are sufficiently long, then pre-eruptive cooling and differentiation of cryomagmas would occur. Therefore, relative to deeper-sourced eruptions, they would be richer in ammonia and/or methanol, and less prone to solidification during ascent. If volcanic and lacustrine environments are concurrent, then geothermal systems rich in organic materials may provide suitable conditions for the emergence of life.

  8. Lake-floor sediment texture and composition of a hydrothermally-active, volcanic lake, Lake Rotomahana

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Muir, S. L.; Hendy, C. H.

    2016-03-01

    Young volcanic lakes undergo a transition from rapid, post-eruptive accumulation of volcaniclastic sediment to slower pelagic settling under stable lake conditions, and may also be influenced by sublacustrine hydrothermal systems. Lake Rotomahana is a young (129 year-old), hydrothermally-active, volcanic lake formed after the 1886 Tarawera eruption, and provides a unique insight into the early evolution of volcanic lake systems. Lake-bottom sediment cores, 20-46 cm in length, were taken along a transect across the lake and characterised with respect to stratigraphy, facies characteristics (i.e., grain size, componentry) and pore water silica concentrations. The sediments generally comprise two widespread facies: (i) a lower facies of light grey to grey, very fine lacustrine silt derived from the unconsolidated pyroclastic deposits that mantled the catchment area immediately after the eruption, which were rapidly reworked and redeposited into the lake basin; and (ii) an upper facies of dark, fine-sandy diatomaceous silt, that settled from the pelagic zone of the physically stable lake. Adjacent to sublacustrine hydrothermal vents, the upper dark facies is absent, and the upper part of the light grey to grey silt is replaced by a third localised facies comprised of hydrothermally altered pale yellow to yellowish brown, laminated silt with surface iron-rich encrustations. Microspheres, which are thought to be composed of amorphous silica, although some may be halloysite, have precipitated from pore water onto sediment grains, and are associated with a decrease in pore water silicon concentration. Lake Rotomahana is an example of a recently-stabilised volcanic lake, with respect to sedimentation, that shows signs of early sediment silicification in the presence of hydrothermal activity.

  9. Palos Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site]

    Palos Crater has been suggested as a future landing site for Mars Missions. This crater has a channel called Tinto Vallis, which enters from the south. This site was suggested as a landing site because it may contain lake deposits. Palos Crater is named in honor of the port city in Spain from which Christopher Columbus sailed on his way to the New World in August of 1492. The floor of Palos Crater appears to be layered in places providing further evidence that this site may in fact have been the location of an ancient lake.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  10. Whole-genome sequencing reveals small genomic regions of introgression in an introduced crater lake population of threespine stickleback.

    PubMed

    Yoshida, Kohta; Miyagi, Ryutaro; Mori, Seiichi; Takahashi, Aya; Makino, Takashi; Toyoda, Atsushi; Fujiyama, Asao; Kitano, Jun

    2016-04-01

    Invasive species pose a major threat to biological diversity. Although introduced populations often experience population bottlenecks, some invasive species are thought to be originated from hybridization between multiple populations or species, which can contribute to the maintenance of high genetic diversity. Recent advances in genome sequencing enable us to trace the evolutionary history of invasive species even at whole-genome level and may help to identify the history of past hybridization that may be overlooked by traditional marker-based analysis. Here, we conducted whole-genome sequencing of eight threespine stickleback (Gasterosteus aculeatus) individuals, four from a recently introduced crater lake population and four of the putative source population. We found that both populations have several small genomic regions with high genetic diversity, which resulted from introgression from a closely related species (Gasterosteus nipponicus). The sizes of the regions were too small to be detected with traditional marker-based analysis or even some reduced-representation sequencing methods. Further amplicon sequencing revealed linkage disequilibrium around an introgression site, which suggests the possibility of selective sweep at the introgression site. Thus, interspecies introgression might predate introduction and increase genetic variation in the source population. Whole-genome sequencing of even a small number of individuals can therefore provide higher resolution inference of history of introduced populations. PMID:27069575

  11. Bacterioplankton communities of Crater Lake, OR: Dynamic changes with euphotic zone food web structure and stable deep water populations

    USGS Publications Warehouse

    Urbach, E.; Vergin, K.L.; Larson, G.L.; Giovannoni, S.J.

    2007-01-01

    The distribution of bacterial and archaeal species in Crater Lake plankton varies dramatically over depth and with time, as assessed by hybridization of group-specific oligonucleotides to RNA extracted from lakewater. Nonmetric, multidimensional scaling (MDS) analysis of relative bacterial phylotype densities revealed complex relationships among assemblages sampled from depth profiles in July, August and September of 1997 through 1999. CL500-11 green nonsulfur bacteria (Phylum Chloroflexi) and marine Group I crenarchaeota are consistently dominant groups in the oxygenated deep waters at 300 and 500 m. Other phylotypes found in the deep waters are similar to surface and mid-depth populations and vary with time. Euphotic zone assemblages are dominated either by ??-proteobacteria or CL120-10 verrucomicrobia, and ACK4 actinomycetes. MDS analyses of euphotic zone populations in relation to environmental variables and phytoplankton and zooplankton population structures reveal apparent links between Daphnia pulicaria zooplankton population densities and microbial community structure. These patterns may reflect food web interactions that link kokanee salmon population densities to community structure of the bacterioplankton, via fish predation on Daphnia with cascading consequences to Daphnia bacterivory and predation on bacterivorous protists. These results demonstrate a stable bottom-water microbial community. They also extend previous observations of food web-driven changes in euphotic zone bacterioplankton community structure to an oligotrophic setting. ?? 2007 Springer Science+Business Media B.V.

  12. Control of the geomorphic evolution of an active crater: Popocatpetl (Mexico) 1994-2003.

    NASA Astrophysics Data System (ADS)

    Andrés, N.; Zamorano, J. J.; Palacios, D.; Macias, J. L.; Sanjosé, J. J.

    2009-04-01

    Volcanic activity often causes intense and successive geomorphic changes to occur inside a crater. In terms of hazard mitigation, it is important to understand the cause of these changes whether they be exterior lava spills, sequences of explosions or massive glacier melt. Access to an active crater, however, is very difficult and dangerous, so analytical approaches involving remote study must substitute actual fieldwork. Several studies done at Popocatepetl volcano during its most recent eruptive phase that began in December 1994, use remote techniques and are described in Cruz-Reyna et al. (1998), Wright et al. (2002), Martín-Del Pozo et al. (2003), Tanarro et al. (2005), Matiella et al. (2008), and Zamorano et al. (1996,1998), among others. The compendium of results reveals that recent volcanic activity on Popocatépetl is characterized by successive dome growth and destruction inside the crater. Macias and Siebe (2005) even suggest that the walls of the crater may no longer withstand future dome growth. The purpose of this study is to understand the morphologic evolution of the interior of the crater during the most active period of the present eruptive phase on Popocatepetl from 1994 to 2003. The methodology is based on photogrammetry techniques that have been used successfully at volcanic sites by Donnadieu et al. (2003), and on a GIS to organize information, draft maps and 3-D images, and to calculate spatial variations in landforms (Procter et al., 2006; Schilling et al., 2006). Traditional aerial photo interpretation was used for 22 triplets selected from a collection of photos taken by the Mexican Highway and Transport Secretariat, from 1982 to 2003, and enabled us to draft geomorphic maps of the interior of the crater. The photos and maps were rectified and georeferenced with ArcGis software, and then the maps were digitized. The areas containing morphologic units associated with a date (exterior crater walls, colluvial ramps and recent volcanic complex

  13. Subsurface geology, ancient hydrothermal systems and crater excavation processes beneath Lake Rotomahana: Evidence from lithic clasts of the 1886 AD Rotomahana Pyroclastics

    NASA Astrophysics Data System (ADS)

    Pittari, A.; Briggs, R. M.; Bowyer, D. A.

    2016-03-01

    The craters associated with the 1886 AD phreatomagmatic Rotomahana eruption, Okataina Volcanic Centre, New Zealand, and the near-vent geology are now hidden beneath Lake Rotomahana and its post-eruptive sediment fill. Lithic clasts from the near-vent lithic lapilli ash deposits of the Rotomahana Pyroclastics are used in this study to trace geological and geothermal conditions before the eruption, as well as vent excavation dynamics. Near-vent deposit characteristics were described in the field, representative lithic clasts were documented petrographically, and unaltered clasts were analysed for major and trace element compositions. The majority of the lithic clasts were rhyolites with subordinate ignimbrites and hydrothermally altered clasts, and trace siltstone and silicified clasts. The rhyolites were classified into four petrographic groups according to phenocryst content and assemblage and were more diverse with respect to geochemical compositions. Most of the rhyolite lithics in the Rotomahana Pyroclastics did not match the rhyolite domes exposed subaerially around the lake, but did have affinities with the pre-Matahina caldera Wairua Rhyolite, and potentially other older non-exposed domes. Ignimbrites most likely correlated either to the Matahina ignimbrite or older non-exposed units. Hydrothermally altered rhyolite and ignimbrite lithic clasts are common and suggest that there has been a long-lived hydrothermal system in this sector, possibly dating back to early activity of the Okataina Volcanic Centre. The diversity in lithic types indicate a spatial variation in country rock lithology and strength, which probably contributed to the vent position and morphology along the Rotomahana fissure.

  14. A Fluorescein Tracer Release Experiment in the Hydrothermally Active Crater of Vailulu'u Volcano, Samoa

    NASA Astrophysics Data System (ADS)

    Hart, S. R.; Staudigel, H.; Workman, R.; Koppers, A.; Girard, A.

    2001-12-01

    Vailulu'u (Rockne) volcano marks the active end of the Samoa hotspot chain. The volcano is 4400 meters high, with a summit crater 2000 meters wide by 400 meters deep and summit peaks reaching to within 600 meters of the sea surface. The crater is hydrothermally active, as witnessed by intense particulate concentrations in the water column (values to 1.4 NTU's), a particulate smog ``halo'' surrounding the summit and extending out many kilometers, high Mn concentrations and 3He/4He ratios (values to 3.8 ppb and 8.6 Ra, respectively), and bottom-water temperature anomalies of 0.5oC. Basalts from the crater have been dated in the range 5-50 years, and likely reflect eruptions associated with a 1995 earthquake swarm. On April 3, 2001, we released a 20 kg point-source charge of fluorescein dye 30 meters above the 975m deep crater floor. The dye was dissolved in a 180 liter mixture of propanol and water, adjusted to a density 1.3 per mil heavier than the ambient water at the release depth. Released from a rubberized bag by means of a galvanic link. First detection of the released dye was 39 hours after the deployment; the dye was in a 50 meter thick layer, with a concentration peak at 900 meters (relative to the release depth of 945m). Tracking was carried out by a CTD-based fluorometer operated in tow-yo mode from the U.S.C.G. Icebreaker Polar Sea. The detection limit was 25 picograms/gram, and the maximum detected concentration was 18,000 pg/g (if evenly dispersed in the lower 150 meters of water in the crater, the expected concentration would be approx. 130 pg/g). While the dye pool was only surveyed for 4 days due to ship-transit constraints, significant horizontal and vertical dispersion was apparent. Vertical dispersion velocities were typically 0.05 cm/sec; horizontal velocities were typically higher by a factor of 10. An approximate diapycnal or eddy diffusivity, K, can be calculated from the rate of vertical spreading of the dye layer: K = Z2/2(t-t0), where Z is

  15. Anatomy of a sudden onset flood: The 18 March 2007 Crater Lake break-out lahar, Mt. Ruapehu, New Zealand

    NASA Astrophysics Data System (ADS)

    Manville, Vern

    2010-05-01

    Sudden onset floods are significant hazards in many environments and regions around the world, resulting in loss of life, damage to infrastructure, and dramatic geomorphic changes due to the very high rate of energy expenditure associated with high flow velocities and depths. In these transient, highly dynamic phenomena, the evolving floodwave typically undergoes a complex series of interactions with the flowpath, involving multiple feedback loops, to produce spatially and temporarily varying sediment loads that affect their density, viscosity, mobility, peak discharge and absolute volume, and hence their hazardousness. However, due to their unpredictability, ephemeral nature, and high energy they are challenging to characterise adequately, making mitigation difficult. At Mt. Ruapehu, New Zealand, an outburst flood caused by collapse of a tephra barrier impounding a summit Crater Lake generated an opportunity to characterise the downstream evolution of a single discrete floodwave through: (i) multi-parameter measurement of time-series hydraulic parameters at key locations along the channel; (ii) visual observations at manual sampling and gauging sites; (iii) capture of geomorphic changes using pre- and post-event high resolution topographic surveys and vertical aerial and oblique imagery; (iv) stratigraphic logging and granulometric analyses of the flood deposits; and (v) testing and calibration of numerical models using the newly acquired data. On 18 March 2007, the natural dam failed, releasing c. 1 Mm3 of warm, highly mineralised water in less than two hours. The flood rapidly bulked by entraining debris along the steep gorge of the upper Whangaehu valley, more than tripling in size, before debouching onto the Whangaehu Fan where it braided into multiple distributary channels. The flood recollected into a single channel to continue downstream to the coast 215 km from source. Stage, discharge, frontal and flow velocity, sediment-load, and geochemical data show

  16. Hydrothermal activity and subsurface soil complexity: implication for outgassing processes at Solfatara crater, Campi Flegrei caldera

    NASA Astrophysics Data System (ADS)

    Montanaro, Cristian; Mayer, Klaus; Scheu, Bettina; Isaia, Roberto; Mangiacapra, Annarita; Gresse, Marceau; Vandemeulebrouck, Jean; Moretti, Roberto; Dingwell, Donald B.

    2016-04-01

    The Solfatara area and its fumaroles are the main surface phenomena of the vigorous hydrothermal activity within the active Campi Flegrei caldera system. The existing fault system appears to have a major control on outgassing which in turn leads to a strong alteration of the volcanic products. Moreover the maar-nature of the crater, and its filling by more recent volcanic deposits, resulted in a complex fractured and multilayered cap to the rising gases. As a consequence the hydrothermal alteration differently affects the rocks within the crater, including pyroclastic fallout ash beds, pyroclastic density current deposits, breccias and lavas. The induced changes in both original microstructure and physical and mechanical properties of the rocks control the outgassing behavior. Here, we report results from a measurement survey conducted in July 2015, and aimed to characterize the in-situ physical (temperature, humidity) and mechanical (permeability, strength, stiffness) properties. The survey also included a mapping of the surficial hydrothermal features and their distributions. Chemical analyses and laboratory measurements (porosity, granulometry) of selected samples were additionally performed. Results show that the crater floor area comprises very different kinds of soils, from fine grained, thin laminated deposits around the two bubbling Fangaia mud pools, to crusted hummock formations along the SE and NE border of the crater. Dry and solid alunite-rich deposits are present in the western and southern part. Furthermore we observed evidences of a beginning of crust formation within the central part of the crater. A large range of surface temperatures, from boiling point to ambient temperature, were measured throughout the surveyed area. Outgassing occurs mainly along the crack system, which has also generated the crusted hummocks. Elsewhere the fluid circulation in the subsoil is favored by the presence of coarse and highly porous sulfur-hardened levels, whereas

  17. Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon

    USGS Publications Warehouse

    Tourrette, T.Z.L.; Burnett, D.S.; Bacon, C.R.

    1991-01-01

    Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO2), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give DUoxide/liq ??? 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are moderately well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster than the zircons were dissolving. Minimum U, Y, and P concentrations in zircons give maximum DUzrc/liq = 13,DYzrc/liq = 23, and DPzrc/liq = 1, but these are considerably lower than reported by other workers for U and Y. Based on our measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractionation during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in our samples. This demonstrates an actual case of non-equilibrium source retention of accessory phases, which in general could be an important trace-element fractionation mechanism. Our results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites. Rough calculations based on Zr gradients in the glass indicate that the samples could have been partially molten for 800 to 8000 years. ?? 1991.

  18. Uranium and minor-element partitioning in Fe-Ti oxides and zircon from partially melted granodiorite, Crater Lake, Oregon

    SciTech Connect

    La Tourrette, T.Z.; Burnett, D.S. ); Bacon C.R. )

    1991-02-01

    Crystal-liquid partitioning in Fe-Ti oxides and zircon was studied in partially melted granodiorite blocks ejected during the climactic eruption of Mt. Mazama (Crater Lake), Oregon. The blocks, which contain up to 33% rhyolite glass (75 wt% SiO{sub 2}), are interpreted to be portions of the magma chamber walls that were torn off during eruption. The glass is clear and well homogenized for all measured elements except Zr. Results for Fe-Ti oxides give D{sub U}{sup oxide/liq} {approx} 0.1. Partitioning of Mg, Mn, Al, Si, V, and Cr in Fe-Ti oxides indicates that grains surrounded by glass are modestly well equilibrated with the melt for many of the minor elements, while those that are inclusions in relict plagioclase are not. Uranium and ytterbium inhomogeneities in zircons indicate that the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons have only partially equilibrated with the melt and that uranium appears to have been diffusing out of the zircons faster that the zircons were dissolving. Based on the authors measurements and given their low abundances in most rocks, Fe-Ti oxides probably do not play a major role in U-Th fractional during partial melting. The partial melts were undersaturated with zircon and apatite, but both phases are present in the authors samples. This demonstrates an actual case of nonequilibrium source retention of accessory phases, which in general could be an important trace element fractionation mechanism. Their results do not support the hypothesis that liquid structure is the dominant factor controlling trace-element partitioning in high-silica rhyolites.

  19. Impact of acid effluent from Kawah Ijen crater lake on irrigated agricultural soils: Soil chemical processes and plant uptake

    NASA Astrophysics Data System (ADS)

    van Rotterdam-Los, A. M. D.; Heikens, A.; Vriend, S. P.; van Bergen, M. J.; van Gaans, P. F. M.

    2008-12-01

    Volcanogenic contamination of irrigation water, caused by effluent from the hyperacid Ijen crater lake, has severely affected the properties of agricultural soils in East Java, Indonesia. From a comparison of acidified topsoil with subsoil and with top- and subsoil in a reference area, we identified processes responsible for changes in soil and soil solution chemistry induced by acid irrigation water, with emphasis on the nutrients Ca, Mg, Fe, and Mn, and on Al, which may become phytotoxic under acid conditions in soils. Compositional data for bulk soil composition and selective extractions with 1 M KCl and 0.2 M acid ammonium oxalate are used in a mass balance approach to specify element fluxes, including uptake by rice plants. The results show that input via irrigation water has produced an increase in the total aluminum content in the affected topsoil, which is of the same order of magnitude as the increase in labile Al. High bioavailability of Al, as reflected by concentrations in KCl extracts, is consistent with elevated concentrations observed in rice plants. In contrast, and despite the high input via irrigation water, Ca and Mg concentrations have decreased in all measured soil fractions through dissolution of amorphous phases and minerals, and through competition of Al for adsorption sites on the exchange complex and plant roots. Strong leaching is also evident for Fe and especially Mn. In terms of the overall mass balance of the topsoil, plant uptake of Al, Ca, Fe, Mg and Mn is negligible. If the use of acid irrigation would be stopped and the soil pH were to increase to values above 4.5, the observed phytotoxicity of Al will be halted. However, crops may then become fully dependent on the input from irrigation water or fertilizer for essential elements, due to the previous removal from the topsoil through leaching.

  20. Control of the geomorphic evolution of an active crater: Popocatpetl (Mexico) 1994-2003.

    NASA Astrophysics Data System (ADS)

    Andrés, N.; Zamorano, J. J.; Palacios, D.; Macias, J. L.; Sanjosé, J. J.

    2009-04-01

    Volcanic activity often causes intense and successive geomorphic changes to occur inside a crater. In terms of hazard mitigation, it is important to understand the cause of these changes whether they be exterior lava spills, sequences of explosions or massive glacier melt. Access to an active crater, however, is very difficult and dangerous, so analytical approaches involving remote study must substitute actual fieldwork. Several studies done at Popocatepetl volcano during its most recent eruptive phase that began in December 1994, use remote techniques and are described in Cruz-Reyna et al. (1998), Wright et al. (2002), Martín-Del Pozo et al. (2003), Tanarro et al. (2005), Matiella et al. (2008), and Zamorano et al. (1996,1998), among others. The compendium of results reveals that recent volcanic activity on Popocatépetl is characterized by successive dome growth and destruction inside the crater. Macias and Siebe (2005) even suggest that the walls of the crater may no longer withstand future dome growth. The purpose of this study is to understand the morphologic evolution of the interior of the crater during the most active period of the present eruptive phase on Popocatepetl from 1994 to 2003. The methodology is based on photogrammetry techniques that have been used successfully at volcanic sites by Donnadieu et al. (2003), and on a GIS to organize information, draft maps and 3-D images, and to calculate spatial variations in landforms (Procter et al., 2006; Schilling et al., 2006). Traditional aerial photo interpretation was used for 22 triplets selected from a collection of photos taken by the Mexican Highway and Transport Secretariat, from 1982 to 2003, and enabled us to draft geomorphic maps of the interior of the crater. The photos and maps were rectified and georeferenced with ArcGis software, and then the maps were digitized. The areas containing morphologic units associated with a date (exterior crater walls, colluvial ramps and recent volcanic complex

  1. A comparative Study of Circulation Patterns at Active Lava Lakes

    NASA Astrophysics Data System (ADS)

    Lev, Einat; Oppenheimer, Clive; Spampinato, Letizia; Hernandez, Pedro; Unglert, Kathi

    2016-04-01

    Lava lakes present a rare opportunity to study magma dynamics in a large scaled-up "crucible" and provide a unique natural laboratory to ground-truth dynamic models of magma circulation. The persistence of lava lakes allows for long-term observations of flow dynamics and of lava properties, especially compared to surface lava flows. There are currently five persistent lava lakes in the world: Halemaumau in Kilauea (Hawaii, USA), Erta Ale (Ethiopia), Nyiragongo (Congo), Erebus (Antarctica), and Villarica (Chile). Marum and Benbow craters of Ambrym volcano (Vanuatu) and Masaya (Nicaragua) have often hosted lava lakes as well. We use visible-light and thermal infrared time-lapse and video footage collected at all above lakes (except Villarica, where the lake is difficult to observe), and compare the circulation patterns recorded. We calculate lake surface motion from the footage using the optical flow method (Lev et al., 2012) to produce 2D velocity fields. We mined both the surface temperature field and the surface velocity field for patterns using machine learning techniques such as "self-organizing maps (SOMs)" and "principle component analysis (PCA)". We use automatic detection technique to study the configuration of crustal plates at the lakes' surface. We find striking differences among the lakes, in flow direction, flow speed, frequency of changes in flow direction and speed, location and consistency of upwelling and downwelling, and crustal plate configuration. We relate the differences to lake size, shallow conduit geometry, lava viscosity, crystal and gas content, and crust integrity.

  2. Persistent aeolian activity at Endeavour crater, Meridiani Planum, Mars; new observations from orbit and the surface

    NASA Astrophysics Data System (ADS)

    Chojnacki, Matthew; Johnson, Jeffrey R.; Moersch, Jeffrey E.; Fenton, Lori K.; Michaels, Timothy I.; Bell, James F., III

    2015-05-01

    Aeolian-driven bedform activity is now known to occur in many regions of Mars, based on surface and orbital observation of contemporary martian ripple and dune mobility events. Many of these sites have only been monitored with sufficient resolution data for the last few Mars years, when the High Resolution Imaging Science Experiment (HiRISE) began acquiring images of Mars. One exception is the well-monitored Endeavour crater in Meridiani Planum, which was one of the first known sites of unambiguous dune activity (migration and deflation). However, those early detections used lower resolution images over longer temporal baselines (versus the HIRISE data now available), leaving some measurements poorly constrained. New orbital and surface observations of Endeavour show multiple spatial (cm, m, km) and temporal (seasons, Mars year) scales of aeolian-driven surface change, which confirms earlier reports. Dome dunes in the eastern portion of the crater persistently deflate, disseminating dark sand across lighter-toned regolith and/or eroded bright dust, and likely contribute to the crater interior's episodic decreases in orbital albedo measurements. Other dome dunes are detected with the highest migration rates (4-12 m per Mars year) and volumetric sand fluxes reported yet for Mars. Estimated dune construction times or "turnover times" here and elsewhere on Mars are significantly shorter than martian obliquity cycles, implying that it is not necessary to invoke paleoclimate wind regimes to explain current dune morphologies. Located on the crater rim, the Opportunity rover detected evidence for near- and far-field aeolian-driven activity, with observations of spherules/sand movement in the rover workspace, bedform albedo alteration, and dust-lifting events. Observations of intracrater dunes show periodic shifting dark streaks that significantly constrain local wind regimes (directionality and seasonality). Constraints on wind directions from surface and orbital images

  3. Anomalous quartz from the Roter Kamm impact crater, Namibia: Evidence for post-impact hydrothermal activity

    SciTech Connect

    Koeberl, C. Univ. of Vienna ); Fredriksson, K. ); Goetzinger, M. ); Reimold, W.U. )

    1989-08-01

    Centimeter-sized quartz pebbles have been found on the rim of the Roter Kamm impact crater. The Roter Kamm crater has a diameter of about 2.5 km and is situated in the Namib Desert, SWA/Namibia. Because of the sand coverage, impact products are exposed exclusively in the form of ejecta on the crater rim. The quartz pebbles were found close to the main deposits of the impact breccias and show signs of wind abrasion. Thin sections revealed that the pebbles consist of individual quartz domains that are up to 1 mm in size. Under crossed nicols (polarized light), all individual domains show extinction almost simultaneously within {plus minus}2{degree}, which is a rare phenomenon. Microprobe studies, neutron activation analyses, and X-ray diffractometry confirmed that the material consists of pure quartz. The quartz contains three different types of fluid inclusions: primary inclusions that record the formation conditions of the quartz, very small (<1 {mu}m) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. Freezing point depression measurements of the primary inclusions indicate fluid salinities between 18.3 and 19.6 wt% NaCl. Homogenization temperatures (T{sub h}) for the primary inclusions range from 165 to 250{degree}C. The quartz and the primary inclusions may provide evidence for a post-impact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  4. The effect of pressurized magma chamber growth on melt migration and pre-caldera vent locations through time at Mount Mazama, Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Karlstrom, Leif; Wright, Heather M.; Bacon, Charles R.

    2015-02-01

    The pattern of eruptions at long-lived volcanic centers provides a window into the co-evolution of crustal magma transport, tectonic stresses, and unsteady magma generation at depth. Mount Mazama in the Oregon Cascades has seen variable activity over the last 400 ky, including the 50 km3 climactic eruption at ca. 7.7 ka that produced Crater Lake caldera. The physical mechanisms responsible for the assembly of silicic magma reservoirs that are the precursors to caldera-forming eruptions are poorly understood. Here we argue that the spatial and temporal distribution of geographically clustered volcanic vents near Mazama reflects the development of a centralized magma chamber that fed the climactic eruption. Time-averaged eruption rates at Mount Mazama imply an order of magnitude increase in deep magma influx prior to the caldera-forming event, suggesting that unsteady mantle melting triggered a chamber growth episode that culminated in caldera formation. We model magma chamber-dike interactions over ∼50 ky preceding the climactic eruption to fit the observed distribution of surface eruptive vents in space and time, as well as petrologically estimated deep influx rates. Best fitting models predict an expanding zone of dike capture caused by a growing, oblate spheroidal magma chamber with 10-30 MPa of overpressure. This growing zone of chamber influence causes closest approaching regional mafic vent locations as well as more compositionally evolved Mazama eruptions to migrate away from the climactic eruptive center, returning as observed to the center after the chamber drains during the caldera-forming eruption.

  5. The effect of pressurized magma chamber growth on melt migration and pre-caldera vent locations through time at Mount Mazama, Crater Lake, Oregon

    USGS Publications Warehouse

    Karlstrom, Leif; Wright, Heather M.; Bacon, Charles R.

    2015-01-01

    The pattern of eruptions at long-lived volcanic centers provides a window into the co-evolution of crustal magma transport, tectonic stresses, and unsteady magma generation at depth. Mount Mazama in the Oregon Cascades has seen variable activity over the last 400 ky, including the 50 km3 climactic eruption at ca. 7.7 ka that produced Crater Lake caldera. The physical mechanisms responsible for the assembly of silicic magma reservoirs that are the precursors to caldera-forming eruptions are poorly understood. Here we argue that the spatial and temporal distribution of geographically clustered volcanic vents near Mazama reflects the development of a centralized magma chamber that fed the climactic eruption. Time-averaged eruption rates at Mount Mazama imply an order of magnitude increase in deep magma influx prior to the caldera-forming event, suggesting that unsteady mantle melting triggered a chamber growth episode that culminated in caldera formation. We model magma chamber–dike interactions over ∼50 ky preceding the climactic eruption to fit the observed distribution of surface eruptive vents in space and time, as well as petrologically estimated deep influx rates. Best fitting models predict an expanding zone of dike capture caused by a growing, oblate spheroidal magma chamber with 10–30 MPa of overpressure. This growing zone of chamber influence causes closest approaching regional mafic vent locations as well as more compositionally evolved Mazama eruptions to migrate away from the climactic eruptive center, returning as observed to the center after the chamber drains during the caldera-forming eruption.

  6. Active Volcanism Late in Martian History - Evidence from Crater Counts in the Tharsis Region

    NASA Astrophysics Data System (ADS)

    Grier, J. A.; Berman, D. C.; Hartmann, W. K.; Bottke, W. F.; Kesthelyi, L. P.

    2001-11-01

    The current hypothesis of young Martian volcanism is based on several lines of evidence including analyses of Martian meteorites, photogeologic examination of the planet's surface and detailed crater count studies of high resolution images from MGS/MOC. In addition, some possible signs of recent liquid water on Mars may be evidence of active volcanism as a heat source. Early crater count studies were questioned on the basis of two major uncertainties: very small sampling of counts on young flows, and poor absolute surface age estimates on Mars. Our attack on these uncertainties includes both improving the detailed crater count statistics on the large Martian shield volcanoes and their surrounding lava plains, and refining the absolute ages of counted units using new estimates of the crater production rate on Mars. We have obtained counts on Olympus Mons, Pavonis Mons and Arsia Mons. We have targeted areas both on the slopes and inter-volcanic plains, and have begun examining the caldera regions. Our initial examination of the counts of caldera floors indicates terrains with statistically significant age differences, suggesting for some volcanoes sustained episodes of caldera collapse or resurfacing. Our slope and inter-volcanic plains data when plotted with the latest calibrated isochrons yield some very young ages, 10 My or younger for some small flows. The estimated uncertainty in the age data is about a factor of two. Our preliminary conclusions therefore appear to support the hypothesis of very recent volcanism on Mars. However, it is clear that a critical issue regarding crater counting on high resolution MOC images is the necessity of avoiding the ubiquitous dust on the Martian surface. TES data have shown that dust mantles exist over much of the Tharsis region, and it is critical that the ages of the terrains counted do not appear artificially young due to dust cover of some of the craters. We have begun a systematic review of counted MOC images and

  7. Seismic activity noted at Medicine Lake Highlands

    SciTech Connect

    Blum, D.

    1988-12-01

    The sudden rumble of earthquakes beneath Medicine Lake Highlands this fall gave geologists an early warning that one of Northern California's volcanoes may be stirring back to life. Researchers stressed that an eruption of the volcano is not expected soon. But the flurry of underground shocks in late September, combined with new evidence of a pool of molten rock beneath the big volcano, has led them to monitor Medicine Lake with new wariness. The volcano has been dormant since 1910, when it ejected a brief flurry of ash - worrying no one. A federal team plans to take measurements of Medicine Lake, testing for changes in its shape caused by underground pressures. The work is scheduled for spring because snows have made the volcano inaccessible. But the new seismic network is an effective lookout, sensitive to very small increases in activity.

  8. Direct evidence for the origin of low-18O silicic magmas: quenched samples of a magma chamber's partially-fused granitoid walls, Crater Lake, Oregon

    USGS Publications Warehouse

    Bacon, C.R.; Adami, L.H.; Lanphere, M.A.

    1989-01-01

    Partially fused granitoid blocks were ejected in the climactic eruption of Mount Mazama, which was accompanied by collapse of Crater Lake caldera. Quartz, plagioclase, and glass in the granitoids have much lower ??18O values (-3.4 to +4.9???) than any fresh lavas of Mount Mazama and the surrounding region (+5.8 to +7.0???). Oxygen isotope fractionation between phases in granitoids is consistent with equilibrium at T ??? 900??C following subsolidus exchange with hydrothermal fluids of meteoric origin. Assimilation of ??? 10-20% of material similar to these granitoids can account for the O and Sr isotopic compositions of lavas and juvenile pyroclasts derived from the climactic magma chamber, many of which have ??18O values ??? 0.5??? or more lower than comparable lavas of Mount Mazama. The O isotope data provide the only clear evidence for such assimilation because the mineralogy and chemical and radiogenic isotopic compositions of the granitoids (dominantly granodiorite) are similar to those of erupted juvenile magmas. The granitoid blocks from Crater Lake serve as direct evidence for the origin of 18O depletion in large, shallow silicic magma bodies. ?? 1989.

  9. The ICDP Lake Bosumtwi impact crater scientific drilling project (Ghana): Core LB-08A litho-log, related ejecta, and shock recovery experiments

    NASA Astrophysics Data System (ADS)

    Deutsch, Alexander; Luetke, Sabine; Heinrich, Volker

    The 1.07 Myr old Lake Bosumtwi impact crater in Ghana was drilled within the framework of the International Continental Scientific Drilling Project (ICDP). Hole LB-08A, drilled into the outer flank of the central uplift and with a total depth of 451 m, yielded 215.71 m of impact-related rocks. This paper summarizes observations of the lithological logging on core LB-08A. Between a depth of 235.6 and ~260 m, the section consists of a melt-bearing allochthonous, polymict, and mostly clast-supported impact breccia. Down to ~418 m, the section comprises a rather uniform unit of metagraywacke alternating with phyllite to slate (lower greenschist facies); few (par-) autochthonous impact breccia bodies and rare impact dike breccias are present. The lowermost part of the section contains several centimeter- to decimeter-thick melt-bearing breccia dikes in country rocks identical to those occurring above. Omnipresent fracturing was mapped in a qualitative manner. Most prominent shock effects in the uplifted target rocks comprise planar fractures and deformation elements in quartz and polysynthetic twinning in carbonate minerals; the maximum shock pressure as evidenced by quartz is below 26 GPa. The allochthonous breccias occasionally contain a few vol% of melt particles. Suevites occur outside the crater rim, carrying diaplectic crystals, coesite, and ballen quartz as well as true melt glasses and a variety of lithic clasts, among those spectacular staurolite-rich mica-schists. The recorded shock level in the uplifted target rocks is lower than expected and modeled. Shock recovery experiments with analogue carbonaceous graywackes at 34 and 39.5 GPa yielded nearly complete transformation of quartz into diaplectic glass. We therefore exclude a specific shock behavior of the soft, fluid-rich target material (carbonaceous graywackes, shales, slates) in core LB-08A as the prime or only reason for the melt deficit and the generally low shock levels recorded inside the Lake

  10. Variability of passive gas emissions, seismicity, and deformation during crater lake growth at White Island Volcano, New Zealand, 2002-2006

    USGS Publications Warehouse

    Werner, C.; Hurst, T.; Scott, B.; Sherburn, S.; Christenson, B.W.; Britten, K.; Cole-Baker, J.; Mullan, B.

    2008-01-01

    We report on 4 years of airborne measurements of CO2, SO2, and H2S emission rates during a quiescent period at White Island volcano, New Zealand, beginning in 2003. During this time a significant crater lake emerged, allowing scrubbig processes to be investigated. CO2 emissions varied from a baseline of 250 to >2000 t d-1 and demonstrated clear annual cycling that was consistent with numbers of earthquake detections and annual changes in sea level. The annual variability was found to be most likely related to increases in the strain on the volcano during sea level highs, temporarily causing fractures to reduce in size in the upper conduit. SO2 emissions varied from 0 to >400 t d-1 and were clearly affected by scrubbing processes within the first year of take development. Scrubbing caused increases of SO42- and Cl- in lake waters, and the ratio of carbon to total sulphur suggested that elemental sulphur deposition was also significant in the lake during the first year. Careful measurements of the lake level and chemistry allowed estimates of the rate of H2O(g) and HCl(g) input into the lake and suggested that the molar abundances of major gas species (H2O, CO2, SO2, and HCl) during this quiescent phase were similar to fumarolic ratios observed between earlier eruptive periods. The volume of magma estimated from CO2 emissions (0.0 15-0.04 km3) was validated by Cl- increases in the lake, suggesting that the gas and magma are transported from deep to shallow depths as a closed system and likely become open in the upper conduit region. The absence of surface deformation further leads to a necessity of magma convection to supply and remove magma from the degassing depths. Two models of convection configurations are discussed. Copyright 2008 by the American Geophysical Union.

  11. Location and Sampling of Aqueous and Hydrothermal Deposits in Martian Impact Craters

    NASA Astrophysics Data System (ADS)

    Newsom, Horton E.; Hagerty, Justin J.; Thorsos, Ivan E.

    2001-03-01

    Do large craters on Mars represent sites that contain aqueous and hydrothermal deposits that provide clues to astrobiological processes? Are these materials available for sampling in large craters? Several lines of evidence strongly support the exploration of large impact craters to study deposits important for astrobiology. The great depth of impact craters, up to several kilometers relative to the surrounding terrain, can allow the breaching of local aquifers, providing a source of water for lakes and hydrothermal systems. Craters can also be filled with water from outflow channels and valley networks to form large lakes with accompanying sedimentation. Impact melt and uplifted basement heat sources in craters >50 km in diameter should be sufficient to drive substantial hydrothermal activity and keep crater lakes from freezing for thousands of years, even under cold climatic conditions. Fluid flow in hydrothermal systems is focused at the edges of large planar impact melt sheets, suggesting that the edge of the melt sheets will have experienced substantial hydrothermal alteration and mineral deposition. Hydrothermal deposits, fine-grained lacustrine sediments, and playa evaporite deposits may preserve evidence for biogeochemical processes that occurred in the aquifers and craters. Therefore, large craters may represent giant Petri dishes for culturing preexisting life on Mars and promoting biogeochemical processes. Landing sites must be identified in craters where access to the buried lacustrine sediments and impact melt deposits is provided by processes such as erosion from outflow channels, faulting, aeolian erosion, or excavation by later superimposed cratering events. Very recent gully formation and small impacts within craters may allow surface sampling of organic materials exposed only recently to the harsh oxidizing surface environment.

  12. Monitoring crater-wall collapse at active volcanoes: a study of the 12 January 2013 event at Stromboli

    NASA Astrophysics Data System (ADS)

    Calvari, Sonia; Intrieri, Emanuele; Di Traglia, Federico; Bonaccorso, Alessandro; Casagli, Nicola; Cristaldi, Antonio

    2016-05-01

    Crater-wall collapses are fairly frequent at active volcanoes and they are normally studied through the analysis of their deposits. In this paper, we present an analysis of the 12 January 2013 crater-wall collapse occurring at Stromboli volcano, investigated by means of a monitoring network comprising visible and infrared webcams and a Ground-Based Interferometric Synthetic Aperture Radar. The network revealed the triggering mechanisms of the collapse, which are comparable to the events that heralded the previous effusive eruptions in 1985, 2002, 2007 and 2014. The collapse occurred during a period of inflation of the summit cone and was preceded by increasing explosive activity and the enlargement of the crater. Weakness of the crater wall, increasing magmastatic pressure within the upper conduit induced by ascending magma and mechanical erosion caused by vent opening at the base of the crater wall and by lava fingering, are considered responsible for triggering the collapse on 12 January 2013 at Stromboli. We suggest that the combination of these factors might be a general mechanism to generate crater-wall collapse at active volcanoes.

  13. Complex explosive volcanic activity on the Moon within Oppenheimer crater, Icarus

    USGS Publications Warehouse

    Bennett, Kristen A; Horgan, Briony H N; Gaddis, Lisa R.; Greenhagen, Benjamin T; Allen, Carlton C.; Hayne, Paul O; Bell, James F III; Paige, David A.

    2016-01-01

    Oppenheimer Crater is a floor-fractured crater located within the South Pole-Aitken basin on the Moon, and exhibits more than a dozen localized pyroclastic deposits associated with the fractures. Localized pyroclastic volcanism on the Moon is thought to form as a result of intermittently explosive Vulcanian eruptions under low effusion rates, in contrast to the higher-effusion rate, Hawaiian-style fire fountaining inferred to form larger regional deposits. We use Lunar Reconnaissance Orbiter Camera images and Diviner Radiometer mid-infrared data, Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra, and Clementine orbiter Ultraviolet/Visible camera images to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. Mineralogically, we find that the deposits are variable mixtures of orthopyroxene and minor clinopyroxene sourced from the crater floor, juvenile clinopyroxene, and juvenile iron-rich glass, and that the mineralogy of the pyroclastics varies both across the Oppenheimer deposits as a whole and within individual deposits. We observe similar variability in the inferred iron content of pyroclastic glasses, and note in particular that the northwest deposit, associated with Oppenheimer U crater, contains the most iron-rich volcanic glass thus far identified on the Moon, which could be a useful future resource. We propose that this variability in mineralogy indicates variability in eruption style, and that it cannot be explained by a simple Vulcanian eruption. A Vulcanian eruption should cause significant country rock to be incorporated into the pyroclastic deposit; however, large areas within many of the deposits exhibit spectra consistent with high abundances of juvenile phases and very little floor material. Thus, we propose that at least the most recent portion of these deposits must have erupted via a Strombolian or more continuous fire

  14. Meteoritic material at five large impact craters

    NASA Technical Reports Server (NTRS)

    Palme, H.; Janssens, M.-J.; Takahashi, H.; Anders, E.; Hertogen, J.

    1978-01-01

    The paper analyzes the meteoritic material at five multikilometer craters: Clearwater (Lac a l'Eau Claire) East and West (22 and 32 km), Manicouagan (70 km) and Mistastin (28 km), all in Canada; and Lake Bosumtwi (10.5 km), Ghana, which is associated with Ivory Coast tektites. Radiochemical neutron activation analysis is applied to 16 crater samples for the siderophile trace elements Ir, Os, Pd, Ni, Ge, and Re, which are depleted to varying degrees in the earth's crust but are abundant in all meteorites except achondrites. It is found that only two samples, both from Clearwater, exhibit a strong meteoritic signal. The remaining ones fall within or slightly above the range for terrestrial rocks, and therefore at best contain only small meteoritic components. Clearwater East is the first terrestrial impact crater to be associated with a stony meteorite (a C1 or C2 chondrite).

  15. Sixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon

    NASA Astrophysics Data System (ADS)

    Wright, Heather Michelle; Bacon, Charles R.; Vazquez, Jorge A.; Sisson, Thomas W.

    2012-12-01

    The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic-rhyodacitic eruptive deposits (71-7.7 ka) were analyzed to determine variations in volatile-element concentrations and changes in magma storage conditions leading up to and including the climactic eruption of Crater Lake caldera. Temperatures (Fe-Ti oxides) increased through the series of dacites, then decreased, and increased again through the rhyodacites (918-968 to ~950 to 845-895 °C). Oxygen fugacity began at nickel-nickel-oxide buffer (NNO) +0.8 (71 ka), dropped slightly to NNO +0.3, and then climbed to its highest value with the climactic eruption (7.7 ka) at NNO +1.1 log units. In parallel with oxidation state, maximum MI sulfur concentrations were high early in the eruptive sequence (~500 ppm), decreased (to ~200 ppm), and then increased again with the climactic eruption (~500 ppm). Maximum MI sulfur correlates with the Sr content (as a proxy for LREE, Ba, Rb, P2O5) of recharge magmas, represented by basaltic andesitic to andesitic enclaves and similar-aged lavas. These results suggest that oxidized Sr-rich recharge magmas dominated early and late in the development of the pre-climactic dacite-rhyodacite system. Dissolved H2O concentrations in MI do not, however, correlate with these changes in dominant recharge magma, instead recording vapor solubility relations in the developing shallow magma storage and conduit region. Dissolved H2O concentrations form two populations through time: the first at 3-4.6 wt% (with a few extreme values up to 6.1 wt%) and the second at ≤2.4 wt%. CO2 concentrations measured in a subset of these inclusions reach up to 240 ppm in early-erupted deposits (71 ka) and are below detection in climactic deposits (7.7 ka). Combined H2O and CO2

  16. Sixty thousand years of magmatic volatile history before the caldera-forming eruption of Mount Mazama, Crater Lake, Oregon

    USGS Publications Warehouse

    Wright, Heather M.; Bacon, Charles R.; Vazquez, Jorge A.; Sisson, Thomas W.

    2012-01-01

    The well-documented eruptive history of Mount Mazama, Oregon, provides an excellent opportunity to use pre-eruptive volatile concentrations to study the growth of an explosive silicic magmatic system. Melt inclusions (MI) hosted in pyroxene and plagioclase crystals from eight dacitic–rhyodacitic eruptive deposits (71–7.7 ka) were analyzed to determine variations in volatile-element concentrations and changes in magma storage conditions leading up to and including the climactic eruption of Crater Lake caldera. Temperatures (Fe–Ti oxides) increased through the series of dacites, then decreased, and increased again through the rhyodacites (918–968 to ~950 to 845–895 °C). Oxygen fugacity began at nickel–nickel-oxide buffer (NNO) +0.8 (71 ka), dropped slightly to NNO +0.3, and then climbed to its highest value with the climactic eruption (7.7 ka) at NNO +1.1 log units. In parallel with oxidation state, maximum MI sulfur concentrations were high early in the eruptive sequence (~500 ppm), decreased (to ~200 ppm), and then increased again with the climactic eruption (~500 ppm). Maximum MI sulfur correlates with the Sr content (as a proxy for LREE, Ba, Rb, P2O5) of recharge magmas, represented by basaltic andesitic to andesitic enclaves and similar-aged lavas. These results suggest that oxidized Sr-rich recharge magmas dominated early and late in the development of the pre-climactic dacite–rhyodacite system. Dissolved H2O concentrations in MI do not, however, correlate with these changes in dominant recharge magma, instead recording vapor solubility relations in the developing shallow magma storage and conduit region. Dissolved H2O concentrations form two populations through time: the first at 3–4.6 wt% (with a few extreme values up to 6.1 wt%) and the second at ≤2.4 wt%. CO2 concentrations measured in a subset of these inclusions reach up to 240 ppm in early-erupted deposits (71 ka) and are below detection in climactic deposits (7.7 ka). Combined H2O and

  17. Possible seasonal activity of gullies on an sand dune (Russell crater, Mars)

    NASA Astrophysics Data System (ADS)

    Jouannic, Gwénaël.; Gargani, Julien; Costard, François

    2010-05-01

    Recent work has shown that gullies are among the most youthful features on Mars (Malin and Edgett, 2000; Costard et al., 2002; Reiss and Jaumann, 2003, Malin et al., 2006). Here we show that the gullies located on the Russell Crater dune are not only extremely youthful but also seem to be still actives. Various geomorphological features consistent with a seasonal activity suggest reactivated flows over the last three terrestrial years. Moreover, using an assemblage of 26 HiRISE images over a 31 month period (November 2006-May 2009) and superposed with MOLA tracks, we performed a quantitative analysis of the sinuosity and branching of the gullies on the shallow slope of the Russell crater. These geomorphologicals features suggest that debris flow have been formed by a fluid flow. As pure water generally is not thought to be stable on the surface of Mars under current conditions, these gullies could be indicative of a highly localized zone of meta-stability heretofore unidentified in the literature or by a highly mineralized water. Equally, the occurrence of the gullies on a dune may point to a near-surface source, i.e. near surface permafrost (Vedie et al. 2008), that could have been emplaced under conditions associated with late Amazonian obliquity excursions (Costard et al., 2002). Nevertheless, the precise composition of the fluid (CO2, mineralized water,…) is still unknown. Costard, F., Forget, F., Mangold, N., Peulvast, J.P., 2002. Formation of recent martian debris flow by melting of near-surface ground ice at high obliquity. Science, 295, 110-113. Malin, M.C., Edgett, K.E., 2000. Evidence for recent groundwater seepage and surface runoff on Mars. Science, 288, 2330-2335. Malin, M.C., Edgett, K.E., Posiolova, L.V., McColley, S.M., Dobrea, E.Z., 2006. Present day impact crater rate and contemporary gully activity on Mars. Science, 314, 1573-1577. Reiss, D., Jaumann, R., 2003. Recent debris flows on Mars : Seasonal observations of the Russell Crater dune field

  18. Rock fall photogrammetric monitoring in the active crater of Piton de la Fournaise volcano, La Reunion Island

    NASA Astrophysics Data System (ADS)

    Hibert, Clément; Dewez, Thomas; Mangeney, Anne; Grandjean, Gilles; Boissier, Patrice; Catherine, Philippe; Kowalski, Philippe

    2010-05-01

    The collapse of the active crater at Piton de la Fournaise volcano, La Reunion Island, 5th April 2007, offers a rare opportunity to observe frequent rock fall and granular landslides, and test new monitoring techniques. Events concern volumes ranging from single blocks to more massive cliff collapse. The purpose of the presentation is two fold: first, we present a comparison between a Digital Terrain Model (DTM) obtained prior to crater collapse and a DTM extracted from aerial photographs shot in October 2010 (before the eruptive crisis of November 2009 and January 2010). This provides an assessment of morphological changes at the scale of the crater. The second purpose is to describe slope instabilities on the south-western flank of the crater observed since October 2009. These ground-based observations were obtained from a pair of photogrammetric stations deployed along the northern and eastern edges of the crater. These works were conducted within UNDERVOLC project. With this monitoring system we mapped zones affected by rockfalls (departure and accumulation areas) and propose a first estimate of volumes of lava produced by the eruption affecting the inside of the crater since January 2.

  19. Patterned ground as an indicator of periglacial activity in and around Lomonosov Crater, Mars

    NASA Astrophysics Data System (ADS)

    Barrett, Alex; Balme, Matt; Patel, Manish; Hagermann, Axel

    2014-05-01

    A survey of the northern plains of Mars has been conducted to catalogue the distribution of possible periglacial landforms across several large study areas in Acidalia, Utopia and Arcadia Planitiae.. Several hundred HiRISE and CTX images have been surveyed, looking for features indicative of a periglacial environment; patterned ground, solifluction features and scalloped depressions. Non-sorted patterned ground is fairly common across the Northern Plains of Mars where nets of fracture polygons are common at mid to high latitudes. These features are most likely the result of contraction cracking due to temperature changes. The occurrence of fracture polygons is in keeping with the cold, dry environment of Mars. Analogous features on Earth are found in some of the coldest and driest regions of the planet. However other types of patterned ground, such as sorted circles and stripes, tend to occur in warmer and wetter environments as sorted patterned ground is the result of the repeated freezing and thawing of the permafrost active layer. These features require the action of liquid water during the warmer months of the year and are characteristic of a periglacial environment. Such features would not be expected to be as common on Mars, where the surface temperature is only warm enough for water to exist in a liquid state for short periods of time in isolated areas which receive high levels of insolation. Prior studies (e.g. Gallagher et al., 2011, Icarus.) have observed features which appear to be morphologically similar to sorted patterned ground. It is possible that unusual sites where boulders appear organised into stripes and networks could be analogous to these terrestrial periglacial features. Determining where such features occur on Mars could have important implications for understanding the martian environment. Lomonosov Crater, located at 64.9 degrees N, 9.3 degrees W in the northern reaches of Acidalia Planitia, is a 150 km diameter crater surrounded by the

  20. Impact craters on Venus

    NASA Technical Reports Server (NTRS)

    Schaber, G. G.

    1991-01-01

    Compared with volcanism and tectonism, impact cratering on Venus has played an overall minor role in sculpting the present-day landscape. The study of Venus impact craters is vital to help place the chronology of the geologic features on the surface in the context of the planet's geological evolution. The degradation of impact craters also provides information on surface and interior processes, particularly alteration by tectonism and volcanism. Through orbit 1422, Magellan mapped about 450 impact craters, with diameters ranging from 2 to 275 km, within an area of about 226 million sq km, or 49 percent of the planet's surface. These craters and their associated deposits show surprisingly little evidence of degradation at the 75 m/pixel resolution of the Magellan SAR. Remarkably few craters in the Magellan images appear to be in the process of being buried by volcanic deposits or destroyed by tectonic activity.

  1. Transient liquid water and water activity at Gale crater on Mars

    NASA Astrophysics Data System (ADS)

    Martín-Torres, F. Javier; Zorzano, María-Paz; Valentín-Serrano, Patricia; Harri, Ari-Matti; Genzer, Maria; Kemppinen, Osku; Rivera-Valentin, Edgard G.; Jun, Insoo; Wray, James; Bo Madsen, Morten; Goetz, Walter; McEwen, Alfred S.; Hardgrove, Craig; Renno, Nilton; Chevrier, Vincent F.; Mischna, Michael; Navarro-González, Rafael; Martínez-Frías, Jesús; Conrad, Pamela; McConnochie, Tim; Cockell, Charles; Berger, Gilles; R. Vasavada, Ashwin; Sumner, Dawn; Vaniman, David

    2015-05-01

    Water is a requirement for life as we know it. Indirect evidence of transient liquid water has been observed from orbiter on equatorial Mars, in contrast with expectations from large-scale climate models. The presence of perchlorate salts, which have been detected at Gale crater on equatorial Mars by the Curiosity rover, lowers the freezing temperature of water. Moreover, perchlorates can form stable hydrated compounds and liquid solutions by absorbing atmospheric water vapour through deliquescence. Here we analyse relative humidity, air temperature and ground temperature data from the Curiosity rover at Gale crater and find that the observations support the formation of night-time transient liquid brines in the uppermost 5 cm of the subsurface that then evaporate after sunrise. We also find that changes in the hydration state of salts within the uppermost 15 cm of the subsurface, as measured by Curiosity, are consistent with an active exchange of water at the atmosphere-soil interface. However, the water activity and temperature are probably too low to support terrestrial organisms. Perchlorates are widespread on the surface of Mars and we expect that liquid brines are abundant beyond equatorial regions where atmospheric humidity is higher and temperatures are lower.

  2. Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?

    NASA Technical Reports Server (NTRS)

    Koeberl, Christian; Fredriksson, Kurt; Goetzinger, Michael; Reimold, Wolf Uwe

    1989-01-01

    Quartz pebbles from the Roter Kamm impact crater (the Namib Desert, SWA/Namibia) were examined for evidence of impact-induced hydrothermal activity, using results from microprobe analyses, neutron activation analyses, transmission IR spectroscopy, and X-ray diffractometry. It was found that the pebbles consisted of pure quartz, which contains three different types of fluid inclusions. These were identified as primary inclusions (5-10 microns) that record the formation conditions of the quartz, very small (less than 1 micron) secondary inclusions associated with the grain boundaries, and late inclusions of irregular size. It is concluded that the quartz and the primary inclusions may provide evidence for a postimpact phase of extensive hydrothermal activity, generated by the residual heat from the kinetic energy of the impact.

  3. Oxygen isotopes as tracers of tektite source rocks: an example from the Ivory Coast tektites and Lake Bosumtwi Crater

    NASA Astrophysics Data System (ADS)

    Blum, Joel D.; Koeberl, Christian; Chamberlain, C. Page

    1993-03-01

    Oxygen isotope studies of tektites and impact glasses provide an important tool to help in identifying the target lithologies for terrestrial impacts, including the K-T boundary impact. However, such studies may be complicated by modification of the original oxygen isotope values of some source rocks during the tektite formation process either by vapor fractionation or incorporation of meteoric water. To further investigate the relationship between the oxygen isotopic composition of tektites and their source rocks, Ivory Coast tektites and samples of impact glasses and bedrock lithologies from the Bosumtwi Crater in Ghana--which is widely believed to be the source crater for the Ivory Coast tektites--were studied. Our preliminary results suggest that the phyllites and metagraywackes from the Bosumtwi Crater were the predominant source materials for the impact glasses and tektites and that no significant oxygen isotope modification (less than 1 percent delta(O-18)) took place during impact melting. This contrasts with previous studies of moldavites and Australasian tektites and their sedimentary source materials which suggests a 4 to 5 percent lowering of delta(O-18) due to meteoric water incorporation during impact melting.

  4. Oxygen isotopes as tracers of tektite source rocks: An example from the Ivory Coast tektites and Lake Bosumtwi Crater

    NASA Technical Reports Server (NTRS)

    Blum, Joel D.; Koeberl, Christian; Chamberlain, C. Page

    1993-01-01

    Oxygen isotope studies of tektites and impact glasses provide an important tool to help in identifying the target lithologies for terrestrial impacts, including the K-T boundary impact. However, such studies may be complicated by modification of the original oxygen isotope values of some source rocks during the tektite formation process either by vapor fractionation or incorporation of meteoric water. To further investigate the relationship between the oxygen isotopic composition of tektites and their source rocks, Ivory Coast tektites and samples of impact glasses and bedrock lithologies from the Bosumtwi Crater in Ghana--which is widely believed to be the source crater for the Ivory Coast tektites--were studied. Our preliminary results suggest that the phyllites and metagraywackes from the Bosumtwi Crater were the predominant source materials for the impact glasses and tektites and that no significant oxygen isotope modification (less than 1 percent delta(O-18)) took place during impact melting. This contrasts with previous studies of moldavites and Australasian tektites and their sedimentary source materials which suggests a 4 to 5 percent lowering of delta(O-18) due to meteoric water incorporation during impact melting.

  5. Meteoritic material at four Canadian impact craters

    NASA Technical Reports Server (NTRS)

    Wolf, R.; Woodrow, A. B.; Grieve, R. A. F.

    1980-01-01

    Eleven impact melt and six basement rock samples from four craters were analyzed by neutron activation for Au, Co, Cr, Fe, Ge, Ir, Ni, Os, Pd, Re and Se. Wanapitei Lake, Ontario: the impact melts show uniform enrichments corresponding to 1-2% C1-chondrite material. Interelement ratios (Co/Cr, Ni/Cr, Ni/Ir) suggest that the impacting body was a C1-, C2-, or LL-chondrite. Nicholson Lake, North West Territory: Ni, Cr and Co are distinctly more enriched than Ir and Au which tentatively suggests an olivine-rich achondrite (nakhlite or ureilite). Gow Lake, Saskatchewan and Mistastin, Labrador: small enrichments in Ir and Ni; both the low Ir/Ni ratios and low Cr content suggest iron meteorites, but the signals are too weak for conclusive identification. A tentative comparison of meteoritic signatures at 10 large, greater than or equal to 4 km craters and their presumed celestial counterparts (13 Apollo and Amor asteroids) shows more irons and achondrites among known projectile types, and a preponderance of S-type objects, having no known meteoritic equivalent, among asteroids. It is not yet clear that these differences are significant, in view of the tentative nature of the crater identifications and the limited statistics.

  6. Cratering mechanics

    NASA Technical Reports Server (NTRS)

    Ivanov, B. A.

    1986-01-01

    Main concepts and theoretical models which are used for studying the mechanics of cratering are discussed. Numerical two-dimensional calculations are made of explosions near a surface and high-speed impact. Models are given for the motion of a medium during cratering. Data from laboratory modeling are given. The effect of gravitational force and scales of cratering phenomena is analyzed.

  7. GPR profiles of Saddle Mountain scoria deposits on Walker Lake Crater tuff ring in Arizona help understanding of geomorphological response to wildland fire

    NASA Astrophysics Data System (ADS)

    Martinez-Hackert, B.; Schwartz, C.; Williams, K.

    2009-05-01

    Walker Lake tuff ring in the San Francisco Volcanic Field, Arizona, experienced a significant forest fire in 1996. Extensive event scale studies suggested a highly increased (by two orders of magnitude) erosion rate both due to raindrop impact and overland flow. However, the 2.3 million year old cone's materials are partially covered by a 15,000-year-old scoria cone deposit from nearby Saddle Mountain. Although previous studies of the geomorphology of Walker Lake crater provided insight into the Saddle Mountain deposit, new studies have actually shown the extent and depth of the deposit on the cone. We present data obtained with ground penetrating radar (GPR) that gives a clearer data set on the depth (4-7m) of the younger deposit in one of the more extensively studied areas. Data were collected along longitudinal and horizontal profiles along the southwestern part of the cone where the deposit is clearly recognizable on the surface and the wild land fire devastation is enormous. Future analysis will shed quantitative light on the effect that the younger, less cohesive materials has on the increased erosion rates in the event scale to decadal scale erosion rates after wildland fire.

  8. Temporal variation of mass-wasting activity in Mount St. Helens crater, Washington, U. S. A. indicated by seismic activity

    SciTech Connect

    Mills, H.H. )

    1991-11-01

    In the crater of Mount St. Helens, formed during the eruption of 18 May 1980, thousands of rockfalls may occur in a single day, and some rock and dirty-snow avalanches have traveled more than 1 km from their source. Because most seismic activity in the crater is produced by mass wasting, the former can be used to monitor the latter. The number and amplitude of seismic events per unit time provide a generalized measure of mass-wasting activity. In this study 1-min averages of seismic amplitudes were used as an index of rockfall activity during summer and early fall. Plots of this index show the diurnal cycle of rockfall activity and establish that the peak in activity occurs in mid to late afternoon. A correlation coefficient of 0.61 was found between daily maximum temperature and average seismic amplitude, although this value increases to 0.72 if a composite temperature variable that includes the maximum temperature of 1 to 3 preceding days as well as the present day is used. Correlation with precipitation is much weaker.

  9. Palaeoenvironmental history of the Holocene volcanic crater lake Lago d'Averno (central southern Italy) inferred from aquatic mollusc deposits

    NASA Astrophysics Data System (ADS)

    Welter-Schultes, F. W.; Richling, I.

    2000-12-01

    The mollusc record from Lago d'Averno, central southern Italy, provides a detailed 1600-yr record of changes in water quality in response to bradyseismic movements and salinity fluctuations. Bradyseismic vertical land movements and human impact in Roman times led to several transgressions from the Mediterranean Sea, 1 km distant, making the lake a valuable resource for documenting the effect of episodic marine transgressions of a freshwater lake. Low-oxygen-tolerant freshwater molluscs suggest that, at around 900-500 bc the lake had a slowly decreasing medium freshwater quality, resulting from contamination of volcanic origin. Disappearance of the obligate freshwater snails and transgression of low-salinity-tolerant marine species indicate that, after 500 bc, continuous subsidence resulted in episodic marine transgressions from the nearby sea. The construction of a canal that connected the lake with the sea, in 37 bc, is marked by a considerable increase in the number of shells and by arrival of brackish-water-intolerant marine species. Species diversity increased considerably when the area was partly depopulated towards the end of the Roman Empire around ad 400. When the land was slightly uplifted around ad 600-750, the water quality of the lake became less favourable for marine molluscs.

  10. Great Lakes Environmental Issues. Earth Systems - Education Activities for Great Lakes Schools (ES-EAGLS).

    ERIC Educational Resources Information Center

    Sheaffer, Amy L., Ed.

    This activity book is part of a series designed to take a concept or idea from the existing school curriculum and develop it in the context of the Great Lakes using teaching approaches and materials appropriate for students in middle and high school. The subject of this book is environmental issues in the Great Lakes. Students learn about the…

  11. Life in the Great Lakes. Earth Systems - Education Activities for Great Lakes Schools (ES-EAGLS).

    ERIC Educational Resources Information Center

    Sheaffer, Amy L., Ed.

    This activity book is part of a series designed to take a concept or idea from the existing school curriculum and develop it in the context of the Great Lakes using teaching approaches and materials appropriate for students in middle and high school. The theme of this book is life in the Great Lakes. Students learn about shorebird adaptations,…

  12. Craters in the Classroom.

    ERIC Educational Resources Information Center

    McArdle, Heather K.

    1997-01-01

    Details an activity in which students create and study miniature impact craters in the classroom. Engages students in making detailed, meaningful observations, drawing inferences, reaching conclusions based on scientific evidence, and designing experiments to test selected variables. (DDR)

  13. Dreissenid mussels from the Great Lakes contain elevated thiaminase activity

    USGS Publications Warehouse

    Tillitt, D.E.; Riley, S.C.; Evans, A.N.; Nichols, S.J.; Zajicek, J.L.; Rinchard, J.; Richter, C.A.; Krueger, C.C.

    2009-01-01

    We examined thiaminase activity in dreissenid mussels collected at different depths and seasons, and from various locations in Lakes Michigan, Ontario, and Huron. Here we present evidence that two dreissenid mussel species (Dreissena bugensis and D. polymorpha) contain thiaminase activity that is 5-100 fold greater than observed in Great Lakes fishes. Thiaminase activity in zebra mussels ranged from 10,600 to 47,900??pmol g- 1??min- 1 and activities in quagga mussels ranged from 19,500 to 223,800??pmol g- 1??min- 1. Activity in the mussels was greatest in spring, less in summer, and least in fall. Additionally, we observed greater thiaminase activity in dreissenid mussels collected at shallow depths compared to mussels collected at deeper depths. Dreissenids constitute a significant and previously unknown pool of thiaminase in the Great Lakes food web compared to other known sources of this thiamine (vitamin B1)-degrading enzyme. Thiaminase in forage fish of the Great Lakes has been causally linked to thiamine deficiency in salmonines. We currently do not know whether linkages exist between thiaminase activities observed in dreissenids and the thiaminase activities in higher trophic levels of the Great Lakes food web. However, the extreme thiaminase activities observed in dreissenids from the Great Lakes may represent a serious unanticipated negative effect of these exotic species on Great Lakes ecosystems.

  14. Local variations of bulk hydrogen and chlorine content measured at the contact between the Sheepbed and Gillespie Lake units in Yellowknife Bay, Gale Crater, using the DAN instrument onboard Curiosity

    NASA Astrophysics Data System (ADS)

    litvak, M. L.; Mitrofanov, I. G.; Behar, A.; Boynton, W. V.; DeFlores, L.; Fedosov, F.; Golovin, D.; Hardgrove, C. J.; Harshman, K.; Kozyrev, A.; Jun, I.; Kuzmin, R.; Lisov, D.; Malakhov, A.; Milliken, R.; Mischna, M. A.; Moersch, J.; Mokrousov, M.; Nikiforov, S.; Sanin, A.; Shvetsov, V.; Starr, R. D.; Tate, C.; Tretyakov, V.; Vostrukhin, A.; Team, M.

    2013-12-01

    The Curiosity rover successfully landed on Aug 6, 2012, at Gale crater and immediately started continuous surface observations of the surrounding environment at the landing site and then along the rover's traverse. The search for aqueous environments and study of their evolution is considered to be a high priority science activity during these observations. In this paper we have focused on the one aspect of this task related to monitoring local variations of hydrogen distribution in the subsurface at the small horizontal scale of 1-10 m based on neutron spectroscopic methods. This was accomplished using data gathered by the Dynamic Albedo of Neutron (DAN) instrument. These data were specially acquired during the rover's traverse inside a location known as Yellowknife Bay. This campaign was specially organized to test the potential variability of water bulk content across the geologic contact between Sheepbed unit mudstones (the primary target for drilling contact science) and the Gillespie Lake unit (upper unit above Sheepbed). The observation program consisted of a dedicated traverse route selected to being in a position at the drilling sites named John Klein and Cumberland, and then drive up to the contact between Sheepbed and Gillespie, making stops every 0.75-1 m to perform high SNR active neutron measurements. The end of traverse was planned several meters past the contact and the total length of the traverse is estimated to be about 20 m.

  15. Craters on comets

    NASA Astrophysics Data System (ADS)

    Vincent, Jean-Baptiste; Oklay, Nilda; Marchi, Simone; Höfner, Sebastian; Sierks, Holger

    2015-03-01

    This paper reviews the observations of crater-like features on cometary nuclei. We compare potential crater sizes and morphologies, and we discuss the probability of impacts between small asteroids in the Main Belt and a comet crossing this region of the Solar System. Finally, we investigate the fate of the impactor and its chances of survival on the nucleus. We find that comets do undergo impacts although the rapid evolution of the surface erases most of the features and make craters difficult to detect. In the case of a collision between a rocky body and a highly porous cometary nucleus, two specific crater morphologies can be formed: a central pit surrounded by a shallow depression, or a pit, deeper than typical craters observed on rocky surfaces. After the impact, it is likely that a significant fraction of the projectile will remain in the crater. During its two years long escort of comet 67P/Churyumov-Gerasimenko, ESA's mission Rosetta should be able to detect specific silicates signatures at the bottom of craters or crater-like features, as evidence of this contamination. For large craters, structural changes in the impacted region, in particular compaction of material, will affect the local activity. The increase of tensile strength can extinct the activity by preventing the gas from lifting up dust grains. On the other hand, material compaction can help the heat flux to travel deeper in the nucleus, potentially reaching unexposed pockets of volatiles, and therefore increasing the activity. Ground truth data from Rosetta will help us infer the relative importance of those two effects.

  16. Determination of the mineral stability field of evolving groundwater in the Lake Bosumtwi impact crater and surrounding areas

    NASA Astrophysics Data System (ADS)

    Loh, Yvonne Sena Akosua; Yidana, Sandow Mark; Banoeng-Yakubo, Bruce; Sakyi, Patrick Asamoah; Addai, Millicent Obeng; Asiedu, Daniel Kwadwo

    2016-09-01

    Conventional graphical techniques, mass balance geochemical modelling, and multivariate statistical methods were jointly applied to hydrogeochemical data of groundwater from the fractured rock aquifer system, and surface water in the Bosumtwi and surrounding areas to reveal evolutionary trends and the characteristics of evolving groundwater in the area. Four clusters distinguished from the Q-mode hierarchical cluster analysis (HCA) comprised three main groundwater associations and one surface water group (lake water). Although both water resources are of low mineralization (TDS < 1000 mg/l), it was observed that the groundwater from the upper catchment with hydrochemical facies dominated by Nasbnd Mgsbnd HCO3-, evolves to Casbnd Mgsbnd and mixed cations HCO3- water types at the lower reaches. The lake water on the other hand is Nasbnd HCO3- water type. Results from principal component analyses (PCA) and other geochemical interpretations distinguished three sources of variations in the hydrochemistry. Saturation indices of possible reactive mineral phases show groundwater undersaturation relative to albite, anorthite, aragonite, barite, calcite, chlorite, chrysotile, dolomite, gypsum, k-felspar and talc, and supersaturation with respect to gibbsite, kaolinite, Ca-montmorillonite and k-mica in the area. The PCA and other geochemical interpretation identify weathering of feldspars and carbonate mineral dissolution as predominantly influencing the hydrochemistry of the groundwater. Hydrolysis of the aluminosilicates causes the groundwater to reach equilibrium with kaolinite. In addition to dissolution of silicates, the chemical composition of the lake water has been influenced by evaporation and consequent carbonate saturation.

  17. Business and Education Linkage Activities. Lake County, Illinois.

    ERIC Educational Resources Information Center

    Flesher, Jeffrey W.

    A study was conducted to establish a baseline profile of business and education linkage activities in Lake County, Illinois. Data were collected through a survey questionnaire sent to 242 public and private K-12 schools in Lake County. Two rounds of mailings resulted in the return of 109 usable forms, or 45 percent of the population. Telephone…

  18. Sub-meter desiccation crack patterns imaged by Curiosity at Gale Crater on Mars shed additional light on former lakes evident from examined outcrops

    NASA Astrophysics Data System (ADS)

    Hallet, B.; Sletten, R. S.; Mangold, N.; Oehler, D. Z.; Williams, R. M. E.; Bish, D. L.; Heydari, E.; Rubin, D. M.; Rowland, S. K.

    2015-12-01

    Small-scale desiccation crack patterns (mudcrack-like arrays of uniform ~0.1 to 1 m polygonal domains separated by linear or curving cracks in exposed bedding) imaged by Curiosity in Gale Crater, Mars complement a wealth of diverse data obtained from exposures of sedimentary rocks that point to deposition "in fluvial, deltaic, and lacustrine environments" including an "intracrater lake system likely [to have] existed intermittently for thousands to millions of years …"(e.g. Grotzinger et al., 2015, Science, submitted). We interpret these mudcrack-like patterns, found on many of the bedrock exposures imaged by Curiosity, as desiccation cracks that developed either of two ways: 1) at the soft sediment-air interface like common mudcracks, or 2) at or below the sediment-water interface by synaeresis or diastasis (involving differential compaction). In the context of recent studies of terrestrial mudcracks, and cracks formed experimentally in various wet powders as they loose moisture, these desiccation features reflect diverse aspects of the formative environment. If they formed as mudcracks, some of the lakes were shallow enough to permit the recurrent drying and wetting that can lead to the geometric regularity characteristic of several of sets of mudcracks. Moreover, the water likely contained little suspended sediment otherwise the mudcracks would be buried too rapidly for the crack pattern to persist and to mature into regular polygonal patterns. The preservation of these desiccation crack patterns does not require, but does not exclude, deep burial and exhumation. Although invisible from satellite because of their size, a multitude of Mastcam and Navcam images reveals these informative features in considerable detail. These images complement much evidence, mostly from HiRISE data from several regions, suggesting that potential desiccation polygons on larger scales may be more common on the surface of Mars than generally recognized.

  19. Eastern Floor of Holden Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 15 April 2002) The Science Today's THEMIS image covers territory on the eastern floor of Holden Crater, which is located in region of the southern hemisphere called Noachis Terra. Holden Crater is 154 km in diameter and named after American Astronomer Edward Holden (1846-1914). This image shows a mottled surface with channels, hills, ridges and impact craters. The largest crater seen in this image is 5 km in diameter. This crater has gullies and what appears to be horizontal layers in its walls. The Story With its beautiful symmetry and gullies radially streaming down to the floor, the dominant crater in this image is an impressive focal point. Yet, it is really just a small crater within a much larger one named Holden Crater. Take a look at the context image to the right to see just how much bigger Holden Crater is. Then come back to the image strip that shows the mottled surface of Holden Crater's eastern floor in greater detail, and count how many hills, ridges, channels, and small impact craters can be seen. No perfectly smooth terrain abounds there, that's for sure. The textured terrain of Holden Crater has been particularly intriguing ever since the Mars Orbital Camera on the Mars Global Surveyor spacecraft found evidence of sedimentary rock layers there that might have formed in lakes or shallow seas in Mars' ancient past. This finding suggests that Mars may have been more like Earth long ago, with water on its surface. Holden Crater might even have held a lake long ago. No one knows for sure, but it's an exciting possibility. Why? If water was once on the surface of Mars long enough to form sedimentary materials, maybe it was there long enough for microbial life to have developed too. (Life as we know it just isn't possible without the long-term presence of liquid water.) The question of life on the red planet is certainly tantalizing, but scientists will need to engage in a huge amount of further investigation to begin to know the answer. That

  20. Ultra-high Resolution Mapping of the Inner Crater of the Active Kick'em Jenny Volcano

    NASA Astrophysics Data System (ADS)

    Hart, L.; Scott, C.; Tominaga, M.; Smart, C.; Vaughn, I.; Roman, C.; Carey, S.; German, C. R.; Participants, T.

    2015-12-01

    We conducted high-resolution geological characterization of a 0.015km^2 region of the inner crater of the most active submarine volcano in the Caribbean, Kick'em Jenny, located 8 km off Grenada in the Lesser Antilles Island Arc. We obtained digital still images and microbathymetery at an altitude of 3 m from the seafloor by using stereo cameras and a BlueView system mounted on Remotely Operated Vehicle (ROV) Hercules during the NA054 cruise on E/V Nautilus (Sept. - Oct. 2014). The seafloor images were processed to construct 2-D photo mosaics of the survey area using Standard Hercules Imaging Suite. We systematically classified the photographed seafloor geology based on the distribution of seafloor morphology and the observable rock fragment and outcrop sizes. The center of the crater floor shows a smooth, coherent texture with little variation in sea floor morphology. From immediately outside this area toward the crater rim, we observe an extensive area covered with outcrops, small rocks, and sediment: and within this area, (1) the north section is partially covered by uneven outcrops with elongated lineaments and a course, rugged seafloor with individual rock fragments observable; (2) the middle section contains high variability and heterogeneity in seafloor morphology in a non-systematic manner; and (3) overall, the southern most section displays subdued seafloor features both in space and variability compared to the other areas. The distributions of rock fragments were classified into four distinct sizes. We observe: (i) little variation in size distribution near the center of the crater floor; and (ii) rock fragment size increasing toward the rim of the crater. To obtain a better understanding of the link between variation in seafloor morphology, rock size distribution, and other in situ processes, we compare our observations on the digital photo mosaic to bathymetry data and ROV visuals (e.g. vents and bacterial mats).

  1. Hydrological Evolution and Chemical Structure of the Hyper-acidic Spring-lake System on White Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Christenson, B. W.; Britten, K.; Mazot, A.

    2015-12-01

    White Island has a long and varied history of acid spring discharge and shallow ephemeral lake formation on the Main Crater floor. In the 12 months prior to the onset of the 1976-2000 eruptive episode, mass discharge from the spring system increased ca. 10-fold, pointing to a strong coupling of the hydrothermal environment to the evolving magmatic system. However, between 1976-1978 the formation of numerous eruption vents to 200 m depth in the Western Sub-crater abruptly changed the hydrostatic regime of the volcano, resulting in the reversal of groundwater flow in the massif towards the newly-formed crater(s). This affected not only the style of volcanic activity (leading to phreatic-phreatomagmatic-magmatic eruption cycles), but also led to the demise of the spring system, with total flow from the crater declining by a factor > 100 by 1979. Eruptive activity came to a close soon after moderate Strombolian activity in mid-2000, by which time ephemeral lakes had already started to form in the eruption crater complex. Since 2003 there have been two complete lake filling and evaporative cycles, reflecting varying heat flow through the conduit system beneath the lake. Over these cycles, lake water concentrations of Cl and SO4 varied between ca. 35-150 and 5-45 g/L respectively, with pH values ranging between +1.5 and -1. Springs reappeared on the Main Crater floor in 2004, and their discharges varied with lake level, pointing to the lake level being a primary control over the piezometric surface in the crater area. Springs closest to the crater complex show direct evidence of crater lake water infiltration into the crater floor aquifer, whereas distal spring discharges show compositional variations reflecting vertical displacement of the interface between shallow, dilute condensate and an underlying acidic brine fluid. Evidence suggests that this acidic brine presently contains a significant component of altered seawater. Volcanic unrest in 2012, which included

  2. Active dust devils in Gusev crater, Mars: Observations from the Mars Exploration Rover Spirit

    USGS Publications Warehouse

    Greeley, R.; Whelley, P.L.; Arvidson, R. E.; Cabrol, N.A.; Foley, D.J.; Franklin, B.J.; Geissler, P.G.; Golombek, M.P.; Kuzmin, R.O.; Landis, G.A.; Lemmon, M.T.; Neakrase, L.D.V.; Squyres, S. W.; Thompson, S.D.

    2006-01-01

    A full dust devil "season" was observed from Spirit from 10 March 2005 (sol 421, first active dust devil observed) to 12 December 2005 (sol 691, last dust devil seen); this corresponds to the period Ls 173.2?? to 339.5??, or the southern spring and summer on Mars. Thermal Emission Spectrometer data suggest a correlation between high surface temperatures and a positive thermal gradient with active dust devils in Gusev and that Spirit landed in the waning stages of a dust devil season as temperatures decreased. 533 active dust devils were observed, enabling new characterizations; they ranged in diameter from 2 to 276 m, with most in the range of 10-20 m in diameter, and occurred from about 0930 to 1630 hours local true solar time (with the maximum forming around 1300 hours) and a peak occurrence in southern late spring (Ls ??? 250??). Horizontal speeds of the dust devils ranged from <1 to 21 m/s, while vertical wind speeds within the dust devils ranged from 0.2 to 8.8 m/s. These data, when combined with estimates of the dust content within the dust devils, yield dust fluxes of 3.95 ?? 10-9 to 4.59-4 kg/m2/s. Analysis of the dust devil frequency distribution over the inferred dust devil zone within Gusev crater yields ???50 active dust devils/km2/sol, suggesting a dust loading into the atmosphere of ???19 kg/km2/sol. This value is less than one tenth the estimates by Cantor et al. (2001) for regional dust storms on Mars. Copyright 2006 by the American Geophysical Union.

  3. A novel heat flux study of a geothermally active lake - Lake Rotomahana, New Zealand

    NASA Astrophysics Data System (ADS)

    Tivey, Maurice A.; de Ronde, Cornel E. J.; Tontini, Fabio Caratori; Walker, Sharon L.; Fornari, Daniel J.

    2016-03-01

    A new technique for measuring conductive heat flux in a lake was adapted from the marine environment to allow for multiple measurements to be made in areas where bottom sediment cover is sparse, or even absent. This thermal blanket technique, pioneered in the deep ocean for use in volcanic mid-ocean rift environments, was recently used in the geothermally active Lake Rotomahana, New Zealand. Heat flow from the lake floor propagates into the 0.5 m diameter blanket and establishes a thermal gradient across the known blanket thickness and thereby provides an estimate of the conductive heat flux of the underlying terrain. This approach allows conductive heat flux to be measured over a spatially dense set of stations in a relatively short period of time. We used 10 blankets and deployed them for 1 day each to complete 110 stations over an 11-day program in the 6 × 3 km lake. Results show that Lake Rotomahana has a total conductive heat flux of about 47 MW averaging 6 W/m2 over the geothermally active lake. The western half of the lake has two main areas of high heat flux; 1) a high heat flux area averaging 21.3 W/m2 along the western shoreline, which is likely the location of the pre-existing geothermal system that fed the famous Pink Terraces, mostly destroyed during the 1886 eruption 2) a region southwest of Patiti Island with a heat flux averaging 13.1 W/m2 that appears to be related to the explosive rift that formed the lake in the 1886 Tarawera eruption. A small rise in bottom water temperature over the survey period of 0.01 °C/day suggests the total thermal output of the lake is ~ 112-132 MW and when compared to the conductive heat output suggests that 18-42% of the total thermal energy is by conductive heat transfer.

  4. Radio-echo sounding of 'active' Antarctic subglacial lakes

    NASA Astrophysics Data System (ADS)

    Siegert, M. J.; Ross, N.; Blankenship, D. D.; Young, D. A.; Greenbaum, J. S.; Richter, T.; Rippin, D. M.; Le Brocq, A. M.; Wright, A.; Bingham, R.; Corr, H.; Ferraccioli, F.; Jordan, T. A.; Smith, B. E.; Payne, A. J.; Dowdeswell, J. A.; Bamber, J. L.

    2013-12-01

    Repeat-pass satellite altimetry has revealed 124 discrete surface height changes across the Antarctic Ice Sheet, interpreted to be caused by subglacial lake discharges (surface lowering) and inputs (surface uplift). Few of these active lakes have been confirmed by radio-echo sounding (RES) despite several attempts, however. Over the last 5 years, major geophysical campaigns have acquired RES data from several 'active' lake sites, including the US-UK-Australian ICECAP programme in East Antactica and the UK survey of the Institute Ice Stream in West Antarctica. In the latter case, a targeted RES survey of one 'active' lake was undertaken. RES evidence of the subglacial bed beneath 'active' lakes in both East and West Antarctica will be presented, and the evidence for pooled subglacial water from these data will be assessed. Based on this assessment, the nature of 'active' subglacial lakes, and their associated hydrology and relationship with surrounding topography will be discussed, as will the likelihood of further 'active' lakes in Antarctica. Hydraulic potential map of the Byrd Glacier catchment with contours at 5 MPa intervals. Predicted subglacial flowpaths are shown in blue. Subglacial lakes known from previous geophysical surveys are shown as black triangles while the newly discovered 'Three-tier lakes' are shown in dashed black outline. Surface height change features within the Byrd subglacial catchment are shown in outline and are shaded to indicate whether they were rising or falling during the ICESat campaign. Those features are labelled in-line with the numbering system of Smith et al. (J. Glac. 2009).

  5. Shackleton Crater

    NASA Video Gallery

    This visualization, created using Lunar Reconnaissance Orbiter laser altimeter data, offers a view of Shackleton Crater located in the south pole of the moon. Thanks to these measurements, we now h...

  6. Copernicus (Crater)

    NASA Astrophysics Data System (ADS)

    Murdin, P.

    2000-11-01

    One of the Moon's most conspicuous craters, with a diameter of 93 km, centered at 9.7 °N, 20.1°W. It is named after the Polish astronomer Nicholas Copernicus. It is one of the Moon's younger features, the impact that produced it having taken place an estimated 1 billion years ago. Like other young craters it is surrounded by a system of bright rays formed by ejecta from the impact; the rays from ...

  7. Layered Sediments, Rampart Craters, and Potential Fluvio-Lacustrine Activity in S.W. Arabia Terra, Mars: Support for a History of Aqueous Conditions

    NASA Technical Reports Server (NTRS)

    Oehler, D. Z.; Allen, C. C.; Venechuk, E. M.; Paris, K. N.

    2007-01-01

    Arabia Terra is a unique area on Mars in that it is the only major, equatorial region characterized by high abundances of near-surface water (as measured by gamma ray and neutron spectroscopy). Vernal Crater is a 55 km-diameter structure in southwest Arabia Terra, centered at 6 N, 355.5 E. The crater includes layered sediments, potential remnants of fluvio-lacustrine activity, and indications of aeolian processes. Regional considerations, along with new THEMIS and MOC data, are being assessed to gain insight into the significance of the geomorphic units within Vernal Crater and the geologic history of SW Arabia Terra.

  8. A New Two-phase Flow Model Applied to the 2007 Crater Lake Break-out Lahar, Mt. Ruapehu, New Zealand

    NASA Astrophysics Data System (ADS)

    Sheridan, M. F.; Cordoba, G.; Pitman, E.; Cronin, S. J.; Procter, J.

    2010-12-01

    The 2007 Crater Lake break-out lahar, Mt. Ruapehu, New Zealand, is a complex but well-characterized natural debris flow that follows an intricate course over an array of topographic features (see Manville et al., this conference). Detailed digital terrain data (DEM) and accurate flow characterization allow us to test our computational model with an unusually high level of control for such a large natural flood wave. The new two-phase flow code is imbedded within the TITAN2D framework (Patra et al. 2005) that is widely used in hazard assessment for both dry (granular) and wet (debris flow) flows (Murcia et al., 2010). Because TITAN2D is actually valid for dry flows (avalanches) we developed a new two-phase model based on balance laws for mass and momentum for each phase. The granular material is assumed to obey a Coulomb constitutive relation and the fluid is assumed to be inviscid. The Darcy-Weisbach formulation is used to account for bed friction, and a phenomenological drag coefficient mediates the momentum exchange between phases. The resulting system of 6 partial differential equations are depth averaged and correspond to the Savage and Hutter model in the limit of no fluid, and to the typical shallow water solutions (Ortiz, et al., 2005) for pure water. This model is capable of simulating particle volumetric fractions as dilute as 0.001 and as concentrated as 0.55. To confirm the usefulness of the new code for complex flows we used data from four observation stations at Ruapehu located at runout distances of 2 km, 5 km, 7 km and 9 km. The specific flow data that we compare with the model outcomes include: 1) arrival time of the flood front, 2) maximum flood depth, and 3) flow velocity. The computed values for these flow characteristics are all within about ± 10% of the observed figures. References: Manville, V., et al., 2010, Anatomy of a basin break-out flood: The 2007 Crater Lake break-out lahar, Mt. Ruapehu, New Zealand, this conference. Murcia, H

  9. Spallanzani Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site] (Released 17 July 2002) The craters on Mars display a variety of interior deposits one of which is shown here. Spallanzani Crater is located far enough south that it probably experiences the seasonal growth and retreat of the south polar cap. During the southern hemisphere winter, CO2 frost condenses out of the atmosphere onto the surface and probably brings with it small amounts of dust and even water ice. It is this sort of depositional process that is thought to have produced the polar layered deposits. The layered deposit in Spallanzani Crater shares some similarities with the polar deposits. Whatever the origin of the layered materials, they likely filled the crater at one time. Note how the interior slope of the northern rim displays layered material of similar if less distinct morphology as the main deposit on the floor. The process that filled the crater with sediment has been replaced by the opposite process. Erosion has taken over, leaving behind spectacular stair-stepped mesas and bizarre, contorted landforms. Unlike the interior crater deposits in the equatorial latitudes, the erosional process has not produced the yardang features that indicate wind erosion. It may be that ice was one of the cementing agents of the sediment and perhaps the sublimation of that ice has left the sediment susceptible to erosion. The details of the deposition and erosion of this interesting deposit remain to be discovered.

  10. Monitoring for volcano-hydrothermal activity using continuous gravity and local ground acceleration measurements: New deployments at Inferno Crater, Waimangu and White Island, New Zealand

    NASA Astrophysics Data System (ADS)

    Jolly, Arthur; Fournier, Nico; Cole-Baker, Jeremy; Miller, Craig

    2010-05-01

    Volcanoes with crater lakes are often characterised by shallow hydrothermal systems which display cyclic behaviour (temperature, lake level, chemistry, etc.) and shallow seismic tremor. Present monitoring programmes in New Zealand include routine collection of these observables, but the associated shallow sub-surface processes are still inadequately modelled and poorly understood. Models would be better constrained with the incorporation of additional geophysical parameters. To this end, we have established a new test programme to continuously monitor for micro-gravity variations at New Zealand volcanoes. We utilise a Micro-g-LaCoste gPhone relative gravity meter having 1 Hz sample rate and a measurement precision of 1 microgal to test the viability of gravity monitoring for volcano-hydrothermal systems. We have initially tested the new sensor in a short term deployment (~2 months) at Inferno Crater, Waimangu, New Zealand. Inferno shows dramatic variations in crater lake level (> 7 m range), temperature (>40o C range) and hydrothermally derived tremor, all over a period of ~5 weeks. The amplitude and period of these observables are ideal for testing gravity variations associated with a cycling hydrothermal system because several cycles can be obtained in a relatively short campaign. We have deployed the gravity sensor into a buried vault having a stable concrete base to minimise local environmental influences. This vault is located ~20 meters from Inferno Lake edge (at high stand) and offers sufficient noise reduction to measure the gravitational effects associated with lake level changes. We will show results for the new gravity meter including raw relative gravity measurements and first order corrections (earth-tide, ocean loading, sensor level, temperature, and barometric pressure) to obtain both residual gravity and overprinted local ground accelerations (earthquakes and local tremor). To examine the effects of local ground vibrations on the gravity meter, we

  11. Layers in Terby Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-407, 30 June 2003

    Whether on Earth or Mars, sedimentary rocks provide a record of past environments. Of course, it is difficult to read that record without being able to visit the site. However, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has revealed hundreds of locales on Mars at which sedimentary rocks are exposed at the surface. Terby Crater exhibits hundreds of layers of similar thickness and physical properties--some have speculated these may be the record of an ancient lake or sea. This MOC image shows some of the layer outcrops in Terby Crater. Fans of debris have eroded from the steep, layered slopes in some places. This picture covers an area 3 km (1.9 mi) wide near 27.5oS, 285.7oW. The image is illuminated from the upper left and was obtained in June 2003.

  12. Thermal imaging of Erta 'Ale active lava lake (Ethiopia)

    NASA Astrophysics Data System (ADS)

    Spampinato, L.; Oppenheimer, C.; Calvari, S.; Cannata, A.; Montalto, P.

    2009-04-01

    Active lava lakes represent the uppermost portion of a volume of convective magma exposed to the atmosphere, and provide open windows on magma dynamics within shallow reservoirs. Erta ‘Ale volcano located within the Danakil Depression in Ethiopia, hosts one of the few permanent convecting lava lakes, active at least since the last century. We report here the main features of Erta ‘Ale lake surface investigated using a hand-held infrared thermal camera between 11 and 12 November 2006. In both days, the lake surface was mainly characterized by efficient magma circulation reflecting in the formation of well-marked incandescent cracks and wide crust plates. These crossed the lake from the upwelling to the downwelling margin with mean speeds ranging between 0.01 and 0.15 m s-1. Hot spots opened eventually in the middle of crust plates and/or along cracks. These produced explosive activity lasting commonly between ~10 and 200 sec. Apparent temperatures at cracks ranged between ~700 and 1070˚C, and between ~300 and 500˚C at crust plates. Radiant power output of the lake varied between ~45 and 76 MW according to the superficial activity and continuous resurfacing of the lake. Time series analysis of the radiant power output data reveals cyclicity with a period of ~10 min. The combination of visual and thermal observations with apparent mean temperatures and convection rates allows us to interpret these signals as the periodic release of hot overpressured gas bubbles at the lake surface.

  13. Oudemans Crater

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image of the interior of Oudemans Crater was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) at 1800 UTC (1:00 p.m. EDT) on October 2, 2006, near 9.8 degrees south latitude, 268.5 degrees east longitude. CRISM's image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 20 meters (66 feet) across.

    Oudemans Crater is located at the extreme western end of Valles Marineris in the Sinai Planum region of Mars. The crater measures some 124 kilometers (77 miles) across and sports a large central peak.

    Complex craters like Oudemans are formed when an object, such as an asteroid or comet, impacts the planet. The size, speed and angle at which the object hits all determine the type of crater that forms. The initial impact creates a bowl-shaped crater and flings material (known as ejecta) out in all directions along and beyond the margins of the bowl forming an ejecta blanket. As the initial crater cavity succumbs to gravity, it rebounds to form a central peak while material along the bowl's rim slumps back into the crater forming terraces along the inner wall. If the force of the impact is strong enough, a central peak forms and begins to collapse back into the crater basin, forming a central peak ring.

    The uppermost image in the montage above shows the location of CRISM data on a mosaic taken by the Mars Odyssey spacecraft's Thermal Emission Imaging System (THEMIS). The CRISM data was taken inside the crater, on the northeast slope of the central peak.

    The lower left image is an infrared false-color image that reveals several distinctive deposits. The center of the image holds a ruddy-brown deposit that appears to correlates with a ridge running southwest to northeast. Lighter, buff-colored deposits occupy low areas interspersed within the ruddy-brown deposit. The southeast corner holds small hills that form part of the central peak complex.

    The lower right image shows spectral

  14. Craters on comets

    NASA Astrophysics Data System (ADS)

    Vincent, J.; Oklay, N.; Marchi, S.; Höfner, S.; Sierks, H.

    2014-07-01

    This paper reviews the observations of crater-like features on cometary nuclei. ''Pits'' have been observed on almost all cometary nuclei but their origin is not fully understood [1,2,3,4]. It is currently assumed that they are created mainly by the cometary activity with a pocket of volatiles erupting under a dust crust, leaving a hole behind. There are, however, other features which cannot be explained in this way and are interpreted alternatively as remnants of impact craters. This work focusses on the second type of pit features: impact craters. We present an in-depth review of what has been observed previously and conclude that two main types of crater morphologies can be observed: ''pit-halo'' and ''sharp pit''. We extend this review by a series of analysis of impact craters on cometary nuclei through different approaches [5]: (1) Probability of impact: We discuss the chances that a Jupiter Family Comet like 9P/Tempel 1 or the target of Rosetta 67P/Churyumov-Gerasimenko can experience an impact, taking into account the most recent work on the size distribution of small objects in the asteroid Main Belt [6]. (2) Crater morphology from scaling laws: We present the status of scaling laws for impact craters on cometary nuclei [7] and discuss their strengths and limitations when modeling what happens when a rocky projectile hits a very porous material. (3) Numerical experiments: We extend the work on scaling laws by a series of hydrocode impact simulations, using the iSALE shock physics code [8,9,10] for varying surface porosity and impactor velocity (see Figure). (4) Surface processes and evolution: We discuss finally the fate of the projectile and the effects of the impact-induced surface compaction on the activity of the nucleus. To summarize, we find that comets do undergo impacts although the rapid evolution of the surface erases most of the features and make craters difficult to detect. In the case of a collision between a rocky body and a highly porous

  15. Lake Sediment Records on Climate Change and Human Activities in the Xingyun Lake Catchment, SW China

    PubMed Central

    Zhang, Wenxiang; Ming, Qingzhong; Shi, Zhengtao; Chen, Guangjie; Niu, Jie; Lei, Guoliang; Chang, Fengqin; Zhang, Hucai

    2014-01-01

    Sediments from Xinyun Lake in central Yunnan, southwest China, provide a record of environmental history since the Holocene. With the application of multi-proxy indicators (total organic carbon (TOC), total nitrogen (TN), δ13C and δ15N isotopes, C/N ratio, grain size, magnetic susceptibility (MS) and CaCO3 content), as well as accelerator mass spectrometry (AMS) 14C datings, four major climatic stages during the Holocene have been identified in Xingyun′s catchment. A marked increase in lacustrine palaeoproductivity occurred from 11.06 to 9.98 cal. ka BP, which likely resulted from an enhanced Asian southwest monsoon and warm-humid climate. Between 9.98 and 5.93 cal. ka BP, a gradually increased lake level might have reached the optimum water depth, causing a marked decline in coverage by aquatic plants and lake productivity of the lake. This was caused by strong Asian southwest monsoon, and coincided with the global Holocene Optimum. During the period of 5.60–1.35 cal. ka BP, it resulted in a warm and dry climate at this stage, which is comparable to the aridification of India during the mid- and late Holocene. The intensifying human activity and land-use in the lake catchment since the early Tang Dynasty (∼1.35 cal. ka BP) were associated with the ancient Dian culture within Xingyun’s catchment. The extensive deforestation and development of agriculture in the lake catchment caused heavy soil loss. Our study clearly shows that long-term human activities and land-use change have strongly impacted the evolution of the lake environment and therefore modulated the sediment records of the regional climate in central Yunnan for more than one thousand years. PMID:25033404

  16. Active and Fossil Geothermal Activity at Lake Chapala, Mexico

    NASA Astrophysics Data System (ADS)

    Zârate-del Vall, P.

    2002-12-01

    Geothermal systems are very abundant in the tectonically active zones of the earth's crust and the Citala rift, where Lake Chapala is located, is not the exception. The Lake Chapala basin is characterized by its paleo- and actual geothermal activity that includes: thermal springs, fossil sinter deposits and hydrothermal petroleum manifestations. Thermal springs occur both inside and outside the lake. The spring water in out-shore thermal springs around Lake Chapala is carbonate (Medina-Heredia A, 1986). To the NE area is San Luis Agua Caliente (69°C; ~ 240 mg L-1 [HCO3]1) in the NW at Jocotepec (36°C; ~263mg L-1 [HCO3]-); in the South we find Tuxcueca and Tizap n El Alto (30°C; 193 mg L-1 [HCO3]-). However, there is an exception, the spring water at the San Juan Cosal sector (North), which is sulfate (64-83°C; ~479 mg L-1, [SO4]-2). Examples of in-shore thermal springs are "Los Gorgos" (near South shore) and "El Fuerte" (near East shore and temporary "out-shore" because of actual severe drought); the characterisation of water of this in-shore sites is in progress. On the SE shore and five km NW from Regules village, outcrops a carbonate deposit named "La Calera". This carbonate fossil sinter outcrops 2 km in E-W direction and 600 m in N-S direction and overlays andesitic rock. With a thickness of approximately 5m and a roughly horizontal attitude, the carbonated sinter material is characterized by both massive and banded structure. When massive, it is colored in yellow brownish and grey and elsewhere it shows a pseudo-brecciated structure and when banded, alternated of yellow and dark millimetre bands can be seen; is characterized by vuggy porosity and silica (quartz and chalcedony) vein lets. Under microscope a pseudo-micritic texture is observed; vugs coated by iron oxides, are filled with calcite, and/or quartz, chalcedony and clay minerals. Six samples of carbonate of "La Calera" deposit were analysed for their stable isotopes (LODC-UParis VI). From δ 13

  17. Authentication controversies and impactite petrography of the New Quebec Crater

    NASA Technical Reports Server (NTRS)

    Marvin, Ursula B.; Kring, David A.

    1992-01-01

    The literature reports that led to the current acceptance of New Quebec Crater (Chubb Crater) as an authentic impact crater are reviewed, and it is noted that, for reasons that are not entirely clear, a meteoritic origin for the New Quebec Crater achieved wider acceptance at an earlier data than for the Lake Bosumtwi Crater, for which petrographic and chemical evidence is more abundant and compelling. The petrography of two impact melt samples from the New Quebec Crater was investigated, and new evidence is obtained on the degrees of shock metamorphism affecting the accessory minerals such as apatite, sphene, magnetite, and zircon.

  18. Satellite observations of Lava Lake activity at Nyiragongo volcano, ex-Zaire, during the Rwandan refugee crisis.

    PubMed

    Oppenheimer, C

    1998-09-01

    In June 1994 the summit crater of Nyiragongo volcano, located in the Great Lakes region of central Africa, began to fill with new lava, ending nearly 12 years of quiescence. An earlier eruption of the volcano in 1977 had culminated in the catastrophic draining of a lava lake through fissures in the crater wall, feeding highly mobile lava flows which reached the outskirts of Goma and killed more than 70 people. By July 1994, as many as 20,000 Hutu refugees were arriving in Goma every hour, only 18 km south from the summit of Nyiragongo. The exodus brought more than one million people to the camps near the town raising fears of a repeat of the 1977 eruption. This paper examines the role that satellite remote sensing could have played in surveillance of the volcano during this time, and demonstrates the potential for monitoring this and other volcanoes in the future. Images recorded by the spaceborne Advanced Very High Resolution Radiometer (AVHRR)--freely available over the Internet--provide semi-quantitative information on the activity of the volcano. The aim of this paper is to promote the wider use of readily available technologies. PMID:9753815

  19. Neutron activation analysis of sea-, lake-, and evaporated salt

    NASA Astrophysics Data System (ADS)

    Steinhauser, G.; Sterba, J. H.; Poljanc, K.; Bichler, M.; Buchtela, K.

    2006-01-01

    Salt is essential for human nutrition. Recently, it has become popular in Europe to rather use exotic sea salt or lake salt instead of purified evaporated salt, because of an alleged higher content of trace elements. In this study the content of trace elements and their bioavailability of 19 samples of different types of salt and 1 sample of brine purification sludge were investigated using instrumental neutron activation analysis. In general, sea-, lake-, and evaporated salt are quite pure. Trace elements determined in salt were Al, Br, Co, Cr, Cs, Fe, Rb, Sc, Sr, and Zn; some of them only in individual cases. It was found that, in general, the content of trace elements in sea- or lake salt was higher than in purified salt. Nevertheless, the use of sea- or lake salt does not contribute significantly to the human needs of essential trace elements, because their concentration in salt is too low or their compounds are not bioavailable.

  20. Crater Chains

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The large crater at the top of this THEMIS visible image has several other craters inside of it. Most noticeable are the craters that form a 'chain' on the southern wall of the large crater. These craters are a wonderful example of secondary impacts. They were formed when large blocks of ejecta from an impact crashed back down onto the surface of Mars. Secondaries often form radial patterns around the impact crater that generated them, allowing researchers to trace them back to their origin.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 19.3, Longitude 347.5 East (12.5 West). 19 meter/pixel resolution.

  1. Impact Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site]

    Today marks the 45th anniversary of the dawn of the Space Age (October 4, 1957). On this date the former Soviet Union launched the world's first satellite, Sputnik 1. Sputnik means fellow traveler. For comparison Sputnik 1 weighed only 83.6 kg (184 pounds) while Mars Odyssey weighs in at 758 kg (1,671 pounds).

    This scene shows several interesting geologic features associated with impact craters on Mars. The continuous lobes of material that make up the ejecta blanket of the large impact crater are evidence that the crater ejecta were fluidized upon impact of the meteor that formed the crater. Volatiles within the surface mixed with the ejecta upon impact thus creating the fluidized form. Several smaller impact craters are also observed within the ejecta blanket of the larger impact crater giving a relative timing of events. Layering of geologic units is also observed within the large impact crater walls and floor and may represent different compositional units that erode at variable rates. Cliff faces, dissected gullies, and heavily eroded impact craters are observed in the bottom half of the image at the terminus of a flat-topped plateau.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS

  2. Volatile-Rich Mineral Phases in the Hawaiian Lithosphere: Phlogopites and Carbonates in 0-age Garnet Pyroxenite Xenoliths From Salt Lake Crater, (Oahu, Hawaii).

    NASA Astrophysics Data System (ADS)

    Bizimis, M.; Sen, G.; Salters, V. J.

    2003-12-01

    We present the first detailed Hf, Nd, Sr isotope and trace and major element investigation on clinopyroxene (cpx), garnet, phlogopite and carbonate mineral separates from garnet pyroxenite xenoliths from the Salt Lake crater, Oahu, Hawaii. These xenoliths are brought to the surface by the post-erosional lavas that mark the last stage of the evolution of a Hawaiian volcano. Previous studies have suggested that these pyroxenites are either high pressure cumulates associated with the Honolulu volcanics (HV) post erosional lavas, or MORB-related cumulates at a 80-100 Ma paleo ridge. In both Nd-Hf and Nd-Sr isotope spaces all cpx and garnet data are within the range of the HV and other Hawaiian post-erosional lavas. The Lu-Hf and Sm-Nd isotope systematics of the cpx - garnet pairs give essentially 0 ages, providing the first direct evidence that these garnet pyroxenites are indeed 0-age high pressure cumulates from melts isotopically similar to the HVs. Some 0-age pyroxenites also contain veins with volatile-rich mineral assemblages (phlogopite, carbonates and associated glass pockets), that have infiltrated and reacted with the cpx-garnet matrix. These phlogopites have identical 143Nd/144Nd ratios as the cpx (0.51303) but significantly more radiogenic 87Sr/86Sr (0.7032 - 0.7033 in cpx, 0.70365 - 0.70385 in phlogopites, carbonates and glass). These minerals have higher 87Sr/86Sr (for a given 143Nd/144Nd) than MORBs or HVs and fall at the extension of the horizontal displacement of the post shield and post erosional Hawaiian lavas from the Pacific MORB field in Nd-Sr isotope space. Isotopically then, these volatile phases are more similar to the post-erosional lavas than the shield (Koolau) tholeites, providing new evidence for the involvement of volatiles in the generation of the post-erosional volcanism. The association of these volatile-rich phases with garnet pyroxenites and their absence in the more shallow, spinel peridotites points to a deep (i.e. non

  3. Anatomy of a basin break-out flood: The 2007 Crater Lake break-out lahar, Mt. Ruapehu, New Zealand (Invited)

    NASA Astrophysics Data System (ADS)

    Manville, V.; Lube, G.; Cronin, S. J.; Doyle, E. E.; Cole, S. E.; Procter, J.; Carrivick, J.; Graettinger, A. H.; Massey, C.; Jongens, R.; Watson, J.; Halstead, J.; Keys, H. J.; Lawrence, C.

    2010-12-01

    Break-out floods from natural or artificial impoundments are significant hazards in many environments and regions around the world, resulting in loss of life, damage to infrastructure, and dramatic geomorphic changes due to the very high rate of energy expenditure associated with high flow velocities and depths in newly created or underfit pre-existing channels. At Mt. Ruapehu, New Zealand, a forecast break-out flood from a summit Crater Lake enabled characterisation of the evolution and impact of a discrete floodwave through: (i) multi-parameter measurement of time-series hydraulic parameters at key locations along the channel by automatic equipment and human observers; and (ii) pre- and post-event high resolution topographic surveys and vertical aerial and oblique imagery of the flowpath. Failure of the tephra dam released c. 1.0 Mm3 of warm, highly mineralised water into the steep gorge of the upper Whangaehu River in <2 hours. LiDAR data indicate 4.5 and 1.4 Mm3 of net erosion and deposition respectively along the first 47 km of channel, with most material (65 %) eroded from the steep bedrock/step-pool upper gorge, comprising inputs from various intra- and extra-channel sources. Net erosion continued across the low-gradient Whangaehu Fan, where the flood anastomosed into multiple distributary channels, and the single-thread meandering river valley further downstream. Overall, patterns of erosion and deposition were a complex function of channel gradient, width and expansion ratio. Stage, discharge, sediment-load, geochemical, and frontal and flow velocity data show that the flood wave propagated as a number of compositionally distinct but overlapping kinematic waveforms. A complex series of interactions with the flowpath produced spatially and temporarily varying sediment loads that affected its density, viscosity, mobility, peak discharge and absolute volume. Peak volumetric bulking factor (3.6) and sediment concentrations (63 vol.%) were achieved early, and

  4. Southern Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03583 Southern Crater

    This crater is located south of Agassiz Crater. It is likely that the polar freeze/thaw/frost cycle is responsible for unusual appearance of the ejecta region around the crater.

    Image information: VIS instrument. Latitude 76.2S, Longitude 247.8E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Geomorphic constraints on the geologic history of Gale Crater (Invited)

    NASA Astrophysics Data System (ADS)

    Palucis, M. C.; Dietrich, W. E.; Hayes, A. G.; Williams, R. M.; Calef, F. J.; Sumner, D. Y.; Parker, T. J.; Bridges, N. T.; Team, M.

    2013-12-01

    On August 5, 2012, the Curiosity rover landed in Gale Crater near the Peace Vallis (PV) alluvial fan system. Gale is located on the crustal dichotomy of Mars between the heavily cratered southern highlands and the smoother northern lowlands. Recent crater counts on Gale's ejecta give an age estimate of ~3.6 Ga, corresponding to the Early Hesperian or possibly the Late Noachian (Le Deit et al., 2012). In the region to the south of Gale are similarly-sized craters (e.g. Hershel and Wien) that appear substantially more degraded, are partially to nearly buried, and have subtle rims, indicating that they likely pre-date Gale. Farah Vallis (FV), a large v-shaped channel incised into the southwestern rim of Gale, may have been part of a large regional drainage system (~270,000 km2) originating near Hershel Crater. Ejecta from Gale appear to have partly buried this valley network, implying it was active before the formation of Gale itself (Irwin et al., 2005). Gale also contains an ~5 km high central mound composed of layered material, whose age based on crater counts and superposition relationships, is ~3.6 to 3.8 Ga (Thomson et al., 2011). Here, we use crater counting and geomorphological relationships from mapped features within Gale to extend the work of others in providing a chronology of Gale's multi-stage geologic history. Using CTX imagery we have identified several large fan/delta features within Gale, in addition to those previously identified. These features, combined with topographic benches and morphologic changes from canyons to local fan deposition, suggest a series of large lakes. The largest (-2100 m) would have filled Gale entirely, and the smallest would have been a shallow lake at the distal end of the PV fan. The simplest interpretation, and the one supported by the geomorphology, is that Gale was sourced in part with water from FV and then progressively fell, creating weak shoreline features at several elevations. In addition, we performed a crater

  6. Galle Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 19 June 2002) The Science This image is of part of Galle Crater, located at 51.9S, 29.5W. This image was taken far enough south and late enough into the southern hemisphere fall to catch observe water ice clouds partially obscuring the surface. The most striking aspect of the surface is the dissected layered unit to the left in the image. Other areas also appear to have layering, but they are either more obscured by clouds or are less well defined on the surface. The layers appear to be mostly flat lying and layer boundaries appear as topographic lines would on a map, but there are a few areas where it appears that these layers have been deformed to some level. Other areas of the image contain rugged, mountainous terrain as well as a separate pitted terrain where the surface appears to be a separate unit from the mountains and the layered terrain. The Story Galle Crater is officially named after a German astronomer who, in 1846, was the first to observe the planet Neptune. It is better known, however, as the 'Happy Face Crater.' The image above focuses on too small an area of the crater to see its beguiling grin, but you can catch the rocky line of a 'half-smile' in the context image to the right (to the left of the red box). While water ice clouds make some of the surface harder to see, nothing detracts from the fabulous layering at the center left-hand edge of the image. If you click on the above image, the scalloped layers almost look as if a giant knife has swirled through a landscape of cake frosting. These layers, the rugged, mountains near them, and pits on the surface (upper to middle section of the image on the right-hand side) all create varying textures on the crater floor. With such different features in the same place, geologists have a lot to study to figure out what has happened in the crater since it formed.

  7. Indications of human activity from amino acid and amino sugar analyses on Holocene sediments from lake Lonar, central India

    NASA Astrophysics Data System (ADS)

    Menzel, P.; Gaye, B.; Wiesner, M.; Prasad, S.; Basavaiah, N.; Stebich, M.; Anoop, A.; Riedel, N.; Brauer, A.

    2012-04-01

    The DFG funded HIMPAC (Himalaya: Modern and Past Climates) programme aims to reconstruct Holocene Indian Monsoon climate using a multi-proxy and multi-archive approach. First investigations made on sediments from a ca. 10 m long core covering the whole Holocene taken from the lake Lonar in central India's state Maharashtra, Buldhana District, serve to identify changes in sedimentation, lake chemistry, local vegetation and regional to supra-regional climate patterns. Lake Lonar occupies the floor of an impact crater that formed on the ~ 65 Ma old basalt flows of the Deccan Traps. It covers an area of ca. 1 km2 and is situated in India's core monsoon area. The modern lake has a maximum depth of about 5 m, is highly alkaline, and hyposaline, grouped in the Na-Cl-CO3 subtype of saline lakes. No out-flowing stream is present and only three small streams feed the lake, resulting in a lake level highly sensitive to precipitation and evaporation. The lake is eutrophic and stratified throughout most of the year with sub- to anoxic waters below 2 m depth. In this study the core sediments were analysed for their total amino acid (AA) and amino sugar (AS) content, the amino acid bound C and N percentage of organic C and total N in the sediment and the distribution of individual amino acids. The results roughly show three zones within the core separated by distinct changes in their AA content and distribution. (i) The bottom part of the core from ca. 12000 cal a BP to 11400 cal a BP with very low AA and AS percentage indicating high lithogenic contribution, most probably related to dry conditions. (ii) From 11400 cal a BP to 1200 cal a BP the sediments show moderate AA and AS percentages and low values for the ratios of proteinogenic AAs to their non-proteinogenic degradation products (e.g. ASP/β-ALA; GLU/γ-ABA). (iii) The top part of the core (< 1200 cal a BP) is characterised by an intense increase in total AA and AS, AA-C/Corg and AA-N/Ntotas well as in the ratio of

  8. Centrifuge impact cratering experiment 5

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Transient crates motions, cratering flow fields, crates dynamics, determining impact conditions from total crater welt, centrifuge quarter-space cratering, and impact cratering mechanics research is documented.

  9. Antum Crater

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image shows the location of one of the highest spatial resolution NIMS images acquired. The left image is an airbrush map of the surface of Ganymede from Voyager data. The small square shows the location of Antum crater, target of the high-resolution NIMS image on the right. NIMS spatial resolution is approximately 4 km/pixel and the image is a falsely colored albedo for a single wavelength near 0.8 micrometers.

    Antum is what is known as a dark ray crater, that is, dark lines emanate from the central bright area. This NIMS image is a close-up of the central area and the dark rays are off the edges of the image. Dark ray craters are fairly unusual and are concentrated in one area of Ganymede's surface. They are thought to be composed of material from the body that impacted Ganymede and created the crater, rather than material brought up from the subsurface. Analysis of the NIMS data will yield compositional and mineralogical information on the dark material. This can help us to understand the nature of bodies that 'crash' into the Jupiter system, as did Comet Shoemaker-Levy 9 in 1995, as well as give more information on the history of surface modification on Ganymede.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  10. Methane transport from the active layer to lakes in the Arctic using Toolik Lake, Alaska, as a case study

    PubMed Central

    Paytan, Adina; Lecher, Alanna L.; Dimova, Natasha; Sparrow, Katy J.; Kodovska, Fenix Garcia-Tigreros; Murray, Joseph; Tulaczyk, Slawomir; Kessler, John D.

    2015-01-01

    Methane emissions in the Arctic are important, and may be contributing to global warming. While methane emission rates from Arctic lakes are well documented, methods are needed to quantify the relative contribution of active layer groundwater to the overall lake methane budget. Here we report measurements of natural tracers of soil/groundwater, radon, and radium, along with methane concentration in Toolik Lake, Alaska, to evaluate the role active layer water plays as an exogenous source for lake methane. Average concentrations of methane, radium, and radon were all elevated in the active layer compared with lake water (1.6 × 104 nM, 61.6 dpm⋅m−3, and 4.5 × 105 dpm⋅m−3 compared with 1.3 × 102 nM, 5.7 dpm⋅m−3, and 4.4 × 103 dpm⋅m−3, respectively). Methane transport from the active layer to Toolik Lake based on the geochemical tracer radon (up to 2.9 g⋅m−2⋅y−1) can account for a large fraction of methane emissions from this lake. Strong but spatially and temporally variable correlations between radon activity and methane concentrations (r2 > 0.69) in lake water suggest that the parameters that control methane discharge from the active layer also vary. Warming in the Arctic may expand the active layer and increase the discharge, thereby increasing the methane flux to lakes and from lakes to the atmosphere, exacerbating global warming. More work is needed to quantify and elucidate the processes that control methane fluxes from the active layer to predict how this flux might change in the future and to evaluate the regional and global contribution of active layer water associated methane inputs. PMID:25775530

  11. Crater Landslide

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA06088 Crater Landslide

    This landslide occurs in an unnamed crater southeast of Millochau Crater.

    Image information: VIS instrument. Latitude -24.4N, Longitude 87.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Cydonia Craters

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Eroded mesas and secondary craters dot the landscape in this area of the Cydonia Mensae region. The single oval-shaped crater displays a 'butterfly' ejecta pattern, indicating that the crater formed from a low-angle impact.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 32.9, Longitude 343.8 East (16.2 West). 19 meter/pixel resolution.

  13. Crater Clouds

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA06085 Crater Clouds

    The crater on the right side of this image is affecting the local wind regime. Note the bright line of clouds streaming off the north rim of the crater.

    Image information: VIS instrument. Latitude -78.8N, Longitude 320.0E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Crater Fill

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03082 Crater Fill

    This VIS image shows part of the floor of an unnamed crater located between the Hellas and Argyre Basins. At some point in time the entire floor of the crater was filled by material. That material is now being eroded away to form the depressions seen in the center and bottom of the image.

    Image information: VIS instrument. Latitude 46.6S, Longitude 5.0E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  15. Lessons from studies of impact crater hydrothermal processes in terrestrial analogs and their implications for impact craters on Mars

    NASA Astrophysics Data System (ADS)

    Newsom, H. E.

    2011-12-01

    Studying hydrothermal processes in terrestrial impact craters as martian analogs has sometimes been fraught with objections, including the Earth's greater abundance of water, the neutral instead of acidic aqueous environments and the composition of the targets. Although recent discoveries have dispelled many objections, some misconceptions remain. For example, the relevance of the Chicxulub crater as a martian analog is sometimes questioned because the target was covered with sediments, including carbonates and sulfates. However the impactites at the Yaxcopoil-1 drill site are derived from the underlying silicate basement. Comparisons can also be difficult because of scale issues, as many terrestrial craters with evidence of hydrothermal activity, e.g. Lonar, Haughton, Ries etc., are smaller than the Martian craters with phyllosilicate signatures (Ehlmann et al., 2010). Summarizing, the results of many studies of terrestrial craters show that: 1) Most terrestrial craters larger than 1.8 km diameter have at least some evidence of aqueous or hydrothermal processes in the form of alteration minerals (e.g., Naumov, 2005). 2) Impact melts in crater fill and ejecta blankets provide heat that can produce hydrothermal alteration if water is available (Newsom, 1980). 3) The uplifted geothermal gradient can be as important a heat source as shock effects. 4) Mineralogical evidence for high-temperature fluids (> 350 oC) is present in the central uplift of the Manson structure, and in the ejecta from the Chicxulub impact, where precipitation of phyllosilicates from hydrothermal fluids has also been described (Newsom et al., 2010). 5) Impact deposits begin hot, but have an extended cooling period during which alteration phases can back react to low temperature phases with corresponding stable isotope signatures. 5) Hydrothermal fluids can travel long distances from their sources (e.g., Chicxulub, Yaxcopoil site) and are often localized to faults or porous breccias (e.g. Sudbury

  16. Crater Highlands, Tanzania

    NASA Technical Reports Server (NTRS)

    2006-01-01

    The Shuttle Radar Topography Mission (SRTM), flown aboard Space Shuttle Endeavour in February 2000, acquired elevation measurements for nearly all of Earth's landmass between 60oN and 56oS latitudes. For many areas of the world SRTM data provide the first detailed three-dimensional observation of landforms at regional scales. SRTM data were used to generate this view of the Crater Highlands along the East African Rift in Tanzania. Landforms are depicted with colored height and shaded relief, using a vertical exaggeration of 2X and a southwestwardly look direction.

    Lake Eyasi is depicted in blue at the top of the image, and a smaller lake occurs in Ngorongoro Crater. Near the image center, elevations peak at 3648 meters (11,968 feet) at Mount Loolmalasin, which is south of Ela Naibori Crater. Kitumbeine (left) and Gelai (right) are the two broad mountains rising from the rift lowlands. Mount Longido is seen in the lower left, and the Meto Hills are in the right foreground.

    Tectonics, volcanism, landslides, erosion and deposition -- and their interactions -- are all very evident in this view. The East African Rift is a zone of spreading between the African (on the west) and Somali (on the east) crustal plates. Two branches of the rift intersect here in Tanzania, resulting in distinctive and prominent landforms. One branch trends nearly parallel the view and includes Lake Eyasi and the very wide Ngorongoro Crater. The other branch is well defined by the lowlands that trend left-right across the image (below center, in green). Volcanoes are often associated with spreading zones where magma, rising to fill the gaps, reaches the surface and builds cones. Craters form if a volcano explodes or collapses. Later spreading can fracture the volcanoes, which is especially evident on Kitumbeine and Gelai Mountains (left and right, respectively, lower center).

    The Crater Highlands rise far above the adjacent savannas, capture moisture from passing air masses

  17. Lake

    ERIC Educational Resources Information Center

    Wien, Carol Anne

    2008-01-01

    The lake is blue black and deep. It is a glaciated finger lake, clawed out of rock when ice retracted across Nova Scotia in a northerly direction during the last ice age. The lake is narrow, a little over a mile long, and deep, 90 to 190 feet in places according to local lore, off the charts in others. The author loves to swim there, with a sense…

  18. Lake Life.

    ERIC Educational Resources Information Center

    Ohrn, Deborah Gore, Ed.

    1993-01-01

    This quarterly publication of the State Historical Society of Iowa features articles and activities for elementary school students. This summer issue focuses on the topic of lake life. The issue includes the following features: (1) "Where the Lakes Are Map"; (2) "Letter from the Lake"; (3) "Lake People"; (4) "Spirit Lake"; (5) "Lake Manawa"; (6)…

  19. Land & Water Interactions in the Great Lakes. Earth Systems - Education Activities for Great Lakes Schools (ES-EAGLS).

    ERIC Educational Resources Information Center

    Sheaffer, Amy L., Ed.

    This activity book is part of a series designed to take a concept or idea from the existing school curriculum and develop it in the context of the Great Lakes using teaching approaches and materials appropriate for students in middle and high school. The subject of this book is land and water interactions. Students examine how the Great Lakes were…

  20. Great Lakes Climate and Water Movement. Earth Systems - Education Activities for Great Lakes Schools (ES-EAGLS).

    ERIC Educational Resources Information Center

    Miller, Heidi, Ed.; Sheaffer, Amy L., Ed.

    This activity book is part of a series designed to take a concept or idea from the existing school curriculum and develop it in the context of the Great Lakes using teaching approaches and materials appropriate for students in middle and high school. The theme of this book is Great Lakes climate and water movement. Students learn about land-sea…

  1. Degradation of Victoria crater, Mars

    USGS Publications Warehouse

    Grant, J. A.; Wilson, S.A.; Cohen, B. A.; Golombek, M.P.; Geissler, P.E.; Sullivan, R.J.; Kirk, R.L.; Parker, T.J.

    2008-01-01

    The ???750 m diameter and ???75 m deep Victoria crater in Meridiani Planum, Mars, is a degraded primary impact structure retaining a ???5 m raised rim consisting of 1-2 m of uplifted rocks overlain by ???3 m of ejecta at the rim crest. The rim is 120-220 m wide and is surrounded by a dark annulus reaching an average of 590 m beyond the raised rim. Comparison between observed morphology and that expected for pristine craters 500-750 m across indicates that the original, pristine crater was close to 600 m in diameter. Hence, the crater has been erosionally widened by ???150 m and infilled by ???50 m of sediments. Eolian processes are responsible for most crater modification, but lesser mass wasting or gully activity contributions cannot be ruled out. Erosion by prevailing winds is most significant along the exposed rim and upper walls and accounts for ???50 m widening across a WNW-ESE diameter. The volume of material eroded from the crater walls and rim is ???20% less than the volume of sediments partially filling the crater, indicating eolian infilling from sources outside the crater over time. The annulus formed when ???1 m deflation of the ejecta created a lag of more resistant hematite spherules that trapped <10-20 cm of darker, regional basaltic sands. Greater relief along the rim enabled meters of erosion. Comparison between Victoria and regional craters leads to definition of a crater degradation sequence dominated by eolian erosion and infilling over time. Copyright 2008 by the American Geophysical Union.

  2. Application of a wide-ranging two-phase Debris Flow Model to the 2007 Crater Lake break-out lahar at Mt. Ruapehu, New Zealand

    NASA Astrophysics Data System (ADS)

    Sheridan, M. F.; Cordoba, G. A.; Pitman, B.; Cronin, S. J.; Procter, J.

    2011-12-01

    landscapes because this code is widely used in hazard assessment (see Murcia et al., 2010). This new model is capable of simulating particle volumetric fractions as dilute as 0.001 and as concentrated as 0.55. The model has been successfully tested on artificial topographic channels as well as on some volcano landscapes. The 2007 Crater Lake break-out lahar, Mt. Ruapehu, New Zealand, is a complex but well-characterized natural debris flow that follows an intricate course through a variety of topographic features. Detailed digital terrain data (DEM) and accurate flow observations allow us to test our computational model with an unusually high level of control for such a large natural flood wave. We compare model and actual data recorded at four Ruapehu observation stations located at runout distances of 2 km, 5 km, 7 km and 9 km. The specific flow data that we compare include: 1) arrival time of the flood front, 2) maximum flood depth, and 3) flow velocity. The computed values for these flow characteristics are all within about ± 10% of the observed figures.

  3. Crater Copernicus

    NASA Technical Reports Server (NTRS)

    1999-01-01

    HUBBLE SHOOTS THE MOON in a change of venue from peering at the distant universe, NASA's Hubble Space Telescope has taken a look at Earth's closest neighbor in space, the Moon. Hubble was aimed at one of the Moon's most dramatic and photogenic targets, the 58 mile-wide (93 km) impact crater Copernicus. The image was taken while the Space Telescope Imaging Spectrograph(STIS) was aimed at a different part of the moon to measure the colors of sunlight reflected off the Moon. Hubble cannot look at the Sun directly and so must use reflected light to make measurements of the Sun's spectrum. Once calibrated by measuring the Sun's spectrum, the STIS can be used to study how the planets both absorb and reflect sunlight.(upper left)The Moon is so close to Earth that Hubble would need to take a mosaic of 130 pictures to cover the entire disk. This ground-based picture from Lick Observatory shows the area covered in Hubble's photomosaic with the WideField Planetary Camera 2..(center)Hubble's crisp bird's-eye view clearly shows the ray pattern of bright dust ejected out of the crater over one billion years ago, when an asteroid larger than a mile across slammed into the Moon. Hubble can resolve features as small as 600 feet across in the terraced walls of the crater, and the hummock-like blanket of material blasted out by the meteor impact.(lower right)A close-up view of Copernicus' terraced walls. Hubble can resolve features as small as 280 feet across.

  4. Backyard bolides: finding a buried impact crater.

    NASA Astrophysics Data System (ADS)

    Poag, C. W.

    1998-10-01

    The author reports the scientific activities that led to his discovery of a huge submerged impact crater in Chesapeake Bay, some 140 km east of Atlantic City, New Jersey. This crater, buried under 350 m of sediment is 80 km wide and almost 1 km deep. Microfossil evidence shows that the crater is approximately 35 million years old. The author futher identified 14 small secondary craters with diamters of 0.4 to 0.5 km diameter within 60 km of the primary crater. These were caused by the impact of huge blocks of material ejected by the primary impact event. In addition, the author identified an intermediate-size primary crater (19 km diameter) in Toms Canyon, some 300 km from the Chesapeake crater and, again from microfossil evidence, identical in age.

  5. Searching for Active Dust Devils in Gusev Crater from Orbit by Mars Express and the Ground from Spirit

    NASA Astrophysics Data System (ADS)

    Whelley, P. L.; Greeley, R.; Neakrase, L. D.; Thompson, S. D.; Foley, D. J.; Landis, G. A.; Squyres, S.; Neukum, G.; Athena Science Team,.; Mars Express HRSC Science Team

    2004-12-01

    Prior to the landing of the Mars Exploration Rover, Spirit, orbital data revealed numerous low albedo features in the Gusev crater landing ellipse attributed to the passage of dust devils (DD), and it was anticipated that active DD would be seen during Spirit operations. Spirit landed on a linear dark feature considered to be a DD track. Mars Express images taken after the landing were compared to images taken just before the landing; results show that many of the dark DD tracks in the area had faded over one martian year (inferred to be the result of dust settling on the surface) and that new tracks had formed in areas north and west of the final Spirit landing site. The three camera systems on Spirit (Pancam, Hazcam, Navcam) were used to search for active DD in a campaign similar to that used successfully during the Mars Pathfinder mission. However, thus far no active DD have been seen from the surface. We attribute this result to one or more of the following: 1) no DD formed within sight of Spirit, 2) observations were not taken at the time or place of DD activity, 3) camera filters/compression values were insufficient to image active DD, or 4) current image processing techniques are inadequate for detecting active DD. As Spirit continues operations, additional searches will be made when resources allow.

  6. Maunder Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 24 May 2002) The Science This image is of a portion of Maunder Crater located at about 49 S and 358 W (2 E). There are a number of interesting features in this image. The lower left portion of the image shows a series of barchan dunes that are traveling from right to left. The sand does not always form dunes as can be seen in the dark and diffuse areas surrounding the dune field. The other interesting item in this image are the gullies that can be seen streaming down from just beneath a number of sharp ridgelines in the upper portion of the image. These gullies were first seen by the MOC camera on the MGS spacecraft and it is though that they formed by groundwater leaking out of the rock layers on the walls of craters. The water runs down the slope and forms the fluvial features seen in the image. Other researchers think that these features could be formed by other fluids, such as CO2. These features are typically seen on south facing slopes in the southern hemisphere, though this image has gullies on north facing slopes as well. The Story Little black squigglies seem to worm their way down the left-hand side of this image. These land features are called barchan (crescent-shaped) dunes. Barchan dunes are found in sandy deserts on Earth, so it's no surprise the Martian wind makes them a common site on the red planet too. They were first named by a Russian scientist named Alexander von Middendorf, who studied the inland desert dunes of Turkistan. The barchan dunes in this image occur in the basin of Maunder crater on Mars, and are traveling from right to left. The sand does not always form dunes, though, as can be seen in the dark areas of scattered sand surrounding the dune field. Look for the streaming gullies that appear just beneath a number of sharp ridgelines in the upper portion of the image. These gullies were first discovered by the Mars Orbital Camera on the Mars Global Surveyor spacecraft. While most crater gullies are found on south

  7. Small Rayed Crater Ejecta Retention Age Calculated from Current Crater Production Rates on Mars

    NASA Technical Reports Server (NTRS)

    Calef, F. J. III; Herrick, R. R.; Sharpton, V. L.

    2011-01-01

    Ejecta from impact craters, while extant, records erosive and depositional processes on their surfaces. Estimating ejecta retention age (Eret), the time span when ejecta remains recognizable around a crater, can be applied to estimate the timescale that surface processes operate on, thereby obtaining a history of geologic activity. However, the abundance of sub-kilometer diameter (D) craters identifiable in high resolution Mars imagery has led to questions of accuracy in absolute crater dating and hence ejecta retention ages (Eret). This research calculates the maximum Eret for small rayed impact craters (SRC) on Mars using estimates of the Martian impactor flux adjusted for meteorite ablation losses in the atmosphere. In addition, we utilize the diameter-distance relationship of secondary cratering to adjust crater counts in the vicinity of the large primary crater Zunil.

  8. Gale Crater Mound

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The eroded, layered deposit in Gale Crater is a mound of material rising 3 km above the crater floor. It has been sculpted by wind and possibly water to produce the dramatic landforms seen today. The origin of the sedimentary material that composes the mound remains a contested issue: was it produced from sedimentation in an ancient crater lake or by airfall onto dry land?

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude -5.1, Longitude 137.5 East (222.5 West). 19 meter/pixel resolution.

  9. Late Holocene hydrous mafic magmatism at the Paint Pot Crater and Callahan flows, Medicine Lake Volcano, N. California and the influence of H2O in the generation of silicic magmas

    USGS Publications Warehouse

    Kinzler, R.J.; Donnelly-Nolan, J. M.; Grove, T.L.

    2000-01-01

    This paper characterizes late Holocene basalts and basaltic andesites at Medicine Lake volcano that contain high pre-eruptive H2O contents inherited from a subduction related hydrous component in the mantle. The basaltic andesite of Paint Pot Crater and the compositionally zoned basaltic to andesitic lavas of the Callahan flow erupted approximately 1000 14C years Before Present (14C years B.P.). Petrologic, geochemical and isotopic evidence indicates that this late Holocene mafic magmatism was characterized by H2O contents of 3 to 6 wt% H2O and elevated abundances of large ion lithophile elements (LILE). These hydrous mafic inputs contrast with the preceding episodes of mafic magmatism (from 10,600 to ~3000 14C years B.P.) that was characterized by the eruption of primitive high alumina olivine tholeiite (HAOT) with low H2O (< 0.2 wt%), lower LILE abundance and different isotopic characteristics. Thus, the mantle-derived inputs into the Medicine Lake system have not always been low H2O, primitive HAOT, but have alternated between HAOT and hydrous subduction related, calc-alkaline basalt. This influx of hydrous mafic magma coincides temporally and spatially with rhyolite eruption at Glass Mountain and Little Glass Mountain. The rhyolites contain quenched magmatic inclusions similar in character to the mafic lavas at Callahan and Paint Pot Crater. The influence of H2O on fractional crystallization of hydrous mafic magma and melting of pre-existing granite crust beneath the volcano combined to produce the rhyolite. Fractionation under hydrous conditions at upper crustal pressures leads to the early crystallization of Fe-Mg silicates and the suppression of plagioclase as an early crystallizing phase. In addition, H2O lowers the saturation temperature of Fe and Mg silicates, and brings the temperature of oxide crystallization closer to the liquidus. These combined effects generate SiO2-enrichment that leads to rhyodacitic differentiated lavas. In contrast, low H2O HAOT

  10. The Explorer's Guide to Impact Craters

    NASA Technical Reports Server (NTRS)

    Chuang, F.; Pierazzo, E.; Osinski, G.

    2005-01-01

    Impact cratering is a fundamental geologic process of our solar system. It competes with other processes, such as plate tectonics, volcanism, fluvial, glacial and eolian activity, in shaping the surfaces of planetary bodies. In some cases, like the Moon and Mercury, impact craters are the dominant landform. On other planetary bodies impact craters are being continuously erased by the action of other geological processes, like volcanism on Io, erosion and plate tectonics on the Earth, tectonic and volcanic resurfacing on Venus, or ancient erosion periods on Mars. The study of crater populations is one of the principal tools for understanding the geologic history of a planetary surface. Among the general public, impact cratering has drawn wide attention through its portrayal in several Hollywood movies. Questions that are raised after watching these movies include: How do scientists learn about impact cratering? , and What information do impact craters provide in understanding the evolution of a planetary surface? Fundamental approaches used by scientists to learn about impact cratering include field work at known terrestrial craters, remote sensing studies of craters on various solid surfaces of solar system bodies, and theoretical and laboratory studies using the known physics of impact cratering.

  11. Meteor Crater: An Analog for Using Landforms to Reconstruct Past Hydrologic Conditions

    NASA Astrophysics Data System (ADS)

    Palucis, M. C.; Dietrich, W. E.; Howard, A. D.; Nishiizumi, K.; Caffee, M. W.; Kring, D. A.

    2015-12-01

    Recent work suggests that debris flow activity has occurred on Mars in the last few million years during high orbital obliquities, but estimating the amount and frequency of liquid water needed to generate these types of flows is still poorly constrained. While it is relatively common to estimate water amounts needed to produce landforms on Mars, such as gullies or alluvial fans, this is something rarely done on Earth. Consequently, there is little field data on the linkage between climate (snowmelt or rainfall events) and the amount of runoff needed to produce specific volumes of sediment in a landform. Here, we present field and modeling data from Meteor Crater, which is a ~50,000 year old impact crater in northern Arizona (USA). Though it is very well preserved, it has developed gullies along its inner wall, similar in form to many gullies on Mars. Meteor Crater, similar to many Martian craters, has also gone through a change in a climate based on the ~30 m of lake sediments on its now dry floor, and what has eroded from its walls has deposited on its floor, making it a closed system. We show using LiDAR-derived topographic data and field observations that debris flows, likely generated by runoff entrainment into talus bordering bedrock cliffs of the crater walls, drove erosion and deposition processes at Meteor Crater. Cosmogenic dating of levee deposits indicates that debris flows ceased in the early Holocene, synchronous with regional drying. For a water-to-rock ratio of 0.3 at the time of transport, which is based on data from rotating drum experiments, it would have taken ~150,000 m3 of water to transport the estimated ~500,000 m3 of debris flow deposits found at the surface of the crater floor. This extensive erosion would require less than 0.4 m of total runoff over the 0.35 km2 upslope source area of the crater, or ~26 mm of runoff per debris flow event. Much more runoff did occur however, as evidenced by lake deposits on the crater floor and Holocene

  12. He, N and C isotopes and fluxes in Aira caldera: Comparative study of hydrothermal activity in Sakurajima volcano and Wakamiko crater, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Roulleau, Emilie; Sano, Yuji; Takahata, Naoto; Kawagucci, Shinsuke; Takahashi, Hirochi

    2013-05-01

    We investigate the degassing activity of an active submarine crater, Wakamiko, and an active sub-aerial volcano, Sakurajima, both located in Aira caldera, southern Kyushu, Japan. We provide 3He/4He, δ13C-CO2 and δ15N data for 15 hot springs, wells and bubbling gas from Sakurajima volcano, along with 3He/4He from seawater at four different sites for both Kagoshima bay and Wakamiko crater. We find a common magmatic 3He/4He ratio for Sakurajima and Wakamiko, 7.2 ± 0.8 Ra, which is consistent with 1) a mixing between air-saturated water (ASW) and MORB-type He, and 2) a common magmatic source located in the center of Aira caldera. Corrected 3He/4He, δ13C-CO2 and CH4/3He data for Sakurajima are correlated with the distance from the volcanic vent (Showa crater), which we attribute to crustal contamination and biogenic reaction. The low δ13C-CO2 values (- 10.1 ± 0.2‰ to - 13.7 ± 0.3‰) observed at Sakurajima may result from the addition of carbon from organic matter from basement rocks in magmatic source. After correction for air-derived nitrogen, we find δ15Nc values range between - 1.7‰ and + 4.3‰ which indicates that magmatic N is dominated by a sedimentary-derived component (up to 65.8%). We calculate Wakamiko fluxes of 4He (975 ± 228 mol/y), 3He (0.011 ± 0.003 mol/y), CO2 (184 ± 43 t/d), and heat (195 ± 22 MW). Our helium and heat fluxes are the first in situ fluxes ever reported for Wakamiko crater. All these Wakamiko fluxes are at least one order of magnitude lower than those observed for Sakurajima (CO2: 1800 t/d; 3He: 0.71 mol/y; heat: 2100 MW): degassing at Sakurajima volcano is much stronger than that at Wakamiko crater. The variation of Sakurajima CO2 flux with time, source (Minamidake or Showa crater) and eruptive activity, appears not to significantly affect the CO2 flux at Wakamiko crater, which is much more stable (132-307 t/d) during the last 30 years. This indicates that there is no link between Sakurajima and Wakamiko degassing

  13. Monitoring and assessment of anthropogenic activities in mountain lakes: a case of the Fifth Triglav Lake in the Julian Alps.

    PubMed

    Ravnikar, Tina; Bohanec, Marko; Muri, Gregor

    2016-04-01

    The Fifth Triglav Lake is a remote mountain lake in the Julian Alps. The area of the Julian Alps where the lake is situated is protected by law and lies within the Triglav National Park. Mountain lakes in Slovenia were considered for a long time as pristine, unpolluted lakes, but analyses in the last decade revealed considerable human impact even in such remote places. Eutrophication or excessive accumulation of nutrients is the main problem of most lakes in the temperate climatic zone, also in Slovenia. Since the introduction of fish in 1991, the lake is going through a series of changes for which we do not know exactly where they lead, so the monitoring and assessment of anthropogenic activities are of great importance. For this purpose, a qualitative multiattribute decision model was developed with DEX method to assess ecological effects on the lake. The extent of the ecological effects on the lake is assessed using four main parameters: the trophic state, lake characteristics, environmental parameters, and anthropogenic stressors. Dependence of environmental impact on various external factors beyond human control, such as temperature, precipitation, retention time, and factors on which we have influence, such as the amount of wastewater and the presence of fish in the lake, were also evaluated. The following data were measured: chlorophyll a, nutrients, TP, oxygen, C/N ratio, nutrients in sediment, temperature, precipitation, retention time, and volume. We made assumptions about fish and wastewater, which we could not measure. The main contributions of this work are the designed model and the obtained findings for the Fifth Triglav Lake that can help not only scientists in understanding the complexity of lake-watershed systems and interactions among system components but also local authorities to manage and monitor the lake aquatic environment in an effective and efficient way. The model is flexible and can be also used for other lakes, assuming that the used

  14. Monitoring and assessment of anthropogenic activities in mountain lakes: a case of the Fifth Triglav Lake in the Julian Alps.

    PubMed

    Ravnikar, Tina; Bohanec, Marko; Muri, Gregor

    2016-03-01

    The Fifth Triglav Lake is a remote mountain lake in the Julian Alps. The area of the Julian Alps where the lake is situated is protected by law and lies within the Triglav National Park. Mountain lakes in Slovenia were considered for a long time as pristine, unpolluted lakes, but analyses in the last decade revealed considerable human impact even in such remote places. Eutrophication or excessive accumulation of nutrients is the main problem of most lakes in the temperate climatic zone, also in Slovenia. Since the introduction of fish in 1991, the lake is going through a series of changes for which we do not know exactly where they lead, so the monitoring and assessment of anthropogenic activities are of great importance. For this purpose, a qualitative multiattribute decision model was developed with DEX method to assess ecological effects on the lake. The extent of the ecological effects on the lake is assessed using four main parameters: the trophic state, lake characteristics, environmental parameters, and anthropogenic stressors. Dependence of environmental impact on various external factors beyond human control, such as temperature, precipitation, retention time, and factors on which we have influence, such as the amount of wastewater and the presence of fish in the lake, were also evaluated. The following data were measured: chlorophyll a, nutrients, TP, oxygen, C/N ratio, nutrients in sediment, temperature, precipitation, retention time, and volume. We made assumptions about fish and wastewater, which we could not measure. The main contributions of this work are the designed model and the obtained findings for the Fifth Triglav Lake that can help not only scientists in understanding the complexity of lake-watershed systems and interactions among system components but also local authorities to manage and monitor the lake aquatic environment in an effective and efficient way. The model is flexible and can be also used for other lakes, assuming that the used

  15. Arkhangelsky Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 12 September 2003

    Arkhangelsky crater is just to the northeast of the giant Argyre impact basin in the southern hemisphere of Mars. This THEMIS visible image shows the floor of this crater with a few dark barchan dunes. Dunes form when wind blows sand across a surface. The barchan dunes shown here form when there isn't a whole lot of sand to start with. If there were, other dune forms would be visible.

    Image information: VIS instrument. Latitude -41.2, Longitude 334.9 East (25.1 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  16. Gusev Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 25 July 2003

    Wrinkle ridges deform the plains in the bottom of Gusev crater, destination of the MER 'Spirit' rover. The plains were likely created from a flood basalt with ridges forming where there were compressional forces. Dark wind streaks come together to form a dark spot at the bottom of the image where the wind has removed a thin layer of bright dust off a dark surface. On the left side of the image a portion of a lobe of material is visible, which may have resulted from a mud or debris flow. This feature was recently identified by the THEMIS team and may represent the most recent deposit in the crater involving water.

    Image information: VIS instrument. Latitude -13.9, Longitude 175.4 East (184.6 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  17. Freedom Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Freedom crater, located in Acidalia Planitia, exhibits a concentric ring pattern in its interior, suggesting that there has been some movement of these materials towards the center of the crater. Slumping towards the center may have been caused by the presence of ground ice mixed in with the sediments. The origin for the scarps on the western edge of the interior deposit is unknown.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude 43.3, Longitude 351.3 East (8.7 West). 19 meter/pixel resolution.

  18. Geologic investigation of layered mound of Henry Crater, Mars: Implications for history of ancient hydrological activities in the region

    NASA Astrophysics Data System (ADS)

    Sarkar, Samarpita; Sinha, Rishitosh Kumar; Banerjee, Debabrata; Vijayan, S.

    2016-07-01

    Craters around the Schiaparelli Basin (sim460 km diameter; 2.71^circS 16.77^circE) on Mars are distributed in a unique combination that includes infilled craters with mound on their floors. The mounds have preserved intriguing layers in stratigraphy that has exposed pristine sets of geomorphic and geochemical signatures bearing strong implications towards understanding geological history of Mars. With a view to avail the maximum scientific benefit from this unique geological assemblage on Mars, we have carried out remote analysis of stratigraphy of layers exposed over Henry crater's (sim150 km diameter; 10.79^circN 23.45^circE) mound (rising sim2km from floor) to infer the origin and episodes of geological events occurred in the region. Henry crater is situated approximately 500 km northeast of Schiaparelli Basin. Using crater counting technique the age of the topmost surface of the crater mound is found to be sim3.64 Ga since the exposure of this strata post complete infilling. The stratigraphy of consistent and conformable layers in the crater interior acts as a proxy of the long-lived event of sediment deposition in a rather quiescent condition. Distinct layering can be traced across the crater from the mound to the crater wall across the floor. Evidence for differential erosion of deposited materials, wherein local geological setup developed in the different parts of the crater interior is preserved. Using MRO HiRISE & CTX images, distinct spatial distribution of morphological features distributed in stratigraphy is observed that reveals the dominant geological agents behind their formation, viz. temporal hydrological and eolian processes. The morphological features were aided with an understanding of the composition of the exposed sedimentary succession. MRO CRISM based mineralogical investigation reveals diagnostic signature of the hydrated sulfate mineral Kieserite. Based on the thermodynamic properties of Kieserite and apparent lack of desiccation cracks in

  19. Crater chains on Mercury

    NASA Astrophysics Data System (ADS)

    Shevchenko, V.; Skobeleva, T.

    After discovery of disruption comet Shoemaker-Levy 9 into fragment train before it's collision with Jupiter there was proposed that linear crater chains on the large satellites of Jupiter and on the Moon are impact scars of past tidally disrupted comets.It's known that radar images have revealed the possible presence of water ice deposits in polar regions of Mercury. Impacts by a few large comets seem to provide the best explanation for both the amount and cleanliness of the ice deposits on Mercury because they have a larger volatile content that others external sources, for example, asteroid. A number of crater chains on the surface of Mercury are most likely the impact tracks of "fragment trains" of comets tidally disrupted by Sun or by Mercury and are not secondary craters. Mariner 10 image set (the three Mariner 10 flybys in 1974-1975) was used to recognize the crater chains these did not associate with secondary crater ejecta from observed impact structures. As example, it can be shown such crater chain located near crater Imhotep and crater Ibsen (The Kuiper Quadrangle of Mercury). Resolution of the Mariner 10 image is about 0.54 km/pixel. The crater chain is about 50 km long. It was found a similar crater chain inside large crater Sophocles (The Tolstoj Quadrangle of Mercury). The image resolution is about 1.46 km/pixel. The chain about 50 km long is located in northen part of the crater. Image resolution limits possibility to examine the form of craters strongly. It seems the craters in chains have roughly flat floor and smooth form. Most chain craters are approximately circular. It was examined many images from the Mariner 10 set and there were identified a total 15 crater chains and were unable to link any of these directly to any specific large crater associated with ejecta deposits. Chain craters are remarkably aligned. All distinguished crater chains are superposed on preexisting formations. A total of 127 craters were identified in the 15 recognized

  20. Pollack Crater's White Rock

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This image of White Rock in Pollack crater was taken by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on February 3, 2007 at 1750 UTC (12:50 p.m. EST), near 8 degrees south latitude, 25 degrees east longitude. The CRISM image was taken in 544 colors covering 0.36-3.92 micrometers, and shows features as small as 40 meters (132 feet) across. The region covered is roughly 20 kilometers (12 miles) long and 10 kilometers (6 miles) wide at its narrowest point.

    First imaged by the Mariner 9 spacecraft in 1972, the enigmatic group of wind-eroded ridges known as White Rock has been the subject of many subsequent investigations. White Rock is located on the floor of Pollack Crater in the Sinus Sabaeus region of Mars. It measures some 15 by 18 kilometers (9 by 11 miles) and was named for its light-colored appearance. In contrast-enhanced images, the feature's higher albedo or reflectivity compared with the darker material on the floor of the crater makes it appear white. In reality, White Rock has a dull, reddish color more akin to Martian dust. This higher albedo as well as its location in a topographic low suggested to some researchers that White Rock may be an eroded remnant of an ancient lake deposit. As water in a desert lake on Earth evaporates, it leaves behind white-colored salts that it leached or dissolved out of the surrounding terrain. These salt deposits may include carbonates, sulfates, and chlorides.

    In 2001, the Thermal Emission Spectrometer (TES) on NASA's Mars Global Surveyor measured White Rock and found no obvious signature of carbonates or sulfates, or any other indication that White Rock holds evaporite minerals. Instead, it found Martian dust.

    CRISM's challenge was to obtain greater detail of White Rock's mineralogical composition and how it formed. The instrument operates at a different wavelength range than TES, giving it greater sensitivity to carbonate, sulfate and phyllosilicate (clay-like) minerals. It also

  1. Gale Crater: Formation and post-impact hydrous environments

    NASA Astrophysics Data System (ADS)

    Schwenzer, S. P.; Abramov, O.; Allen, C. C.; Bridges, J. C.; Clifford, S. M.; Filiberto, J.; Kring, D. A.; Lasue, J.; McGovern, P. J.; Newsom, H. E.; Treiman, A. H.; Vaniman, D. T.; Wiens, R. C.; Wittmann, A.

    2012-09-01

    Gale Crater, the landing site of the 2011 Mars Science Laboratory mission, formed in the Late Noachian. It is a 150 km diameter complex impact structure with a central mound (Mount Sharp), the original features of which may be transitional between a central peak and peak ring impact structure. The impact might have melted portions of the substrate to a maximum depth of ˜17 km and produced a minimum of 3600 km3 of impact melt, half of which likely remained within the crater. The bulk of this impact melt would have pooled in an annular depression surrounding the central uplift, creating an impact melt pool as thick as 0.5-1 km. The ejecta blanket surrounding Gale may have been as thick as ˜600 m, which has implications for the amount of erosion that has occurred since Gale Crater formed. After the impact, a hydrothermal system may have been active for several hundred thousand years and a crater lake with associated sediments is likely to have formed. The hydrothermal system, and associated lakes and springs, likely caused mineral alteration and precipitation. In the presence of S-rich host rocks, the alteration phases are modelled to contain sheet silicates, quartz, sulphates, and sulphides. Modelled alteration assemblages may be more complex if groundwater interaction persisted after initial alteration. The warm-water environment might have provided conditions supportive of life. Deep fractures would have allowed for hydraulic connectivity into the deep subsurface, where biotic chemistry (and possibly other evidence of life) may be preserved.

  2. Hydrothermal Alteration at Lonar Crater, India and Elemental Variations in Impact Crater Clays

    NASA Technical Reports Server (NTRS)

    Newsom, H. E.; Nelson, M. J.; Shearer, C. K.; Misra, S.; Narasimham, V.

    2005-01-01

    The role of hydrothermal alteration and chemical transport involving impact craters could have occurred on Mars, the poles of Mercury and the Moon, and other small bodies. We are studying terrestrial craters of various sizes in different environments to better understand aqueous alteration and chemical transport processes. The Lonar crater in India (1.8 km diameter) is particularly interesting being the only impact crater in basalt. In January of 2004, during fieldwork in the ejecta blanket around the rim of the Lonar crater we discovered alteration zones not previously described at this crater. The alteration of the ejecta blanket could represent evidence of localized hydrothermal activity. Such activity is consistent with the presence of large amounts of impact melt in the ejecta blanket. Map of one area on the north rim of the crater containing highly altered zones at least 3 m deep is shown.

  3. Holden Crater/Uzboi Valles

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 17 April 2002) The Science This image, located near 27.0S and 35.5W (324.5E), displays the intersection of Holden Crater with Uzboi Valles. This region of Mars contains a number of features that could be related to liquid water on the surface in the Martian past. Holden Crater contains finely layered sedimentary units that have been subsequently dissected. The hummucky terrain in the bottom half of the image is the remnants of this terrain, though the fine layers are not visible in this image at this resolution. The sedimentary units could have formed through deposition of material in a lacustrine type environment. Alternately, these layers could also be volcanic ash deposits. Uzboi Valles, which enters the crater from the southwest, is a catastrophic outflow channel that formed in the Martian past. The streamlined nature of the topographic features at the intersection of the crater with Uzboi Valles record the erosional pattern of flowing liquid water on the surface of Mars during the episodic outflow event. The Story Mars doesn't have a shortage of rugged terrain, and this area is no exception. While things look pretty quiet now, this cratered region was once the scene of some tremendous action. Long ago in Martian history, an incoming meteoroid probably smashed into the planet and produced a giant impact crater named Holden Crater, which stretches 88 miles across the Martian surface. The history of the area around Holden Crater doesn?t stop there. At some point, a catastrophic flood burst forth on the surface, forming an impressive outflow channel called Uzboi Valles. No one knows exactly how that happened, or whether the water might even have rushed into Holden Crater at some point, forming a long-ago lake. What we do know is that there is a lot of sedimentary material that could have formed in two hypothesized ways: in an ancient lake environment or as volcanic-ash deposits. Scientists are searching for the answers by studying the region where Uzboi

  4. Quebec: Lake Manicouagan

    Atmospheric Science Data Center

    2013-04-17

    ... and other erosional processes have reduced the extent of the crater, with the original diameter estimated at about 100 kilometers. This ... metamorphic effects are abundant in the target rocks of the crater floor. Today Lake Manicouagan serves as a reservoir and is one of ...

  5. Future volcanic lake research: revealing secrets from poorly studied lakes

    NASA Astrophysics Data System (ADS)

    Rouwet, D.; Tassi, F.; Mora-Amador, R. A.

    2012-04-01

    Volcanic lake research boosted after the 1986 Lake Nyos lethal gas burst, a limnic rather than volcanic event. This led to the formation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990's. At Lake Nyos, a degassing pipe is functional since 2001, and two additional pipes were added in 2011, aimed to prevent further limnic eruption events. There are between 150 and 200 volcanic lakes on Earth. Some acidic crater lakes topping active magmatic-hydrothermal systems are monitored continuously or discontinuously. Such detailed studies have shown their usefulness in volcanic surveillance (e.g. Ruapehu, Yugama-Kusatsu-Shiran, Poás). Others are "Nyos-type" lakes, with possible gas accumulation in bottom waters and thus potentially hazardous. "Nyos-type" lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term gas build-up and thus higher potential risk. In temperate climates, such lakes tend to turn over in winter (monomictic), and thus liberating its gas charge yearly. We line out research strategies for the different types of lakes. We believe a complementary, multi-disciplinary approach (geochemistry, geophysics, limnology, biology, statistics, etc.) will lead to new insights and ideas, which can be the base for future following-up and monitoring. After 25 years of pioneering studies on rather few lakes, the scientific community should be challenged to study the many poorly studied volcanic lakes, in order to better constrain the related hazard, based on probabilistic approaches.

  6. High-Silica Rocks and Soils at Gusev Crater, Mars: Distribution, Spectra, and Implications for Past Hydrothermal Activity

    NASA Astrophysics Data System (ADS)

    Rice, M. S.; Bell, J. F.; Wang, A.; Cloutis, E. A.

    2008-12-01

    The Mars Exploration Rover (MER) Spirit has discovered surprisingly high concentrations of amorphous silica in the Inner Basin of the Columbia Hills. As described by Squyres et al. (2008, Science, 320, 1063), within a topographic lowland called Eastern Valley, Spirit's Alpha Particle X-Ray Spectrometer (APXS) measured a composition of >90 wt.% silica at the soil feature "Gertrude Weise", a record high for Mars. The Mössbauer spectrum of this target is featureless. APXS measurements of light-toned nodular outcrops also show high silica concentrations (up to ~72 wt.%), which in some locations co-exist with sulfur-rich soils. Miniature Thermal Emission Spectrometer (Mini-TES) results from the soils and nodules are consistent with opal-A. These deposits have been found adjacent to "Home Plate", a layered plateau interpreted as the product of explosive volcanism. The silica-rich soils and nodules are consistent with sinters and/or residues formed in a hydrothermal system, and may be related to the same hydrovolcanic activity that produced Home Plate. We have begun to map the distribution of high-silica materials in Gusev Crater more extensively using remote sensing, in order to understand the regional extent of possible hydrothermal activity. Spirit's Pancam instrument has collected visible to near-infrared relative reflectance spectra of the region in 11 unique wavelengths. We find that a distinct absorption feature at the longest Pancam wavelength (1009 nm) appears to be characteristic of the high-silica soils and nodules. By mapping the occurrence of this feature with other spectral parameters in Pancam images, we can remotely identify potential amorphous silica deposits elsewhere in the Columbia Hills. Here we present a map with our proposed regional distribution of silica-rich materials within the rover's Gusev Crater traverse area. The mineralogic origin of the 1009nm feature is enigmatic; reflectance spectra of amorphous silica are typically featureless in near

  7. Mineral resources of the Devil's Garden Lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas, Lake County, Oregon

    SciTech Connect

    Keith, W.J.; King, H.D.; Gettings, M.E. ); Johnson, F.L. )

    1988-01-01

    The Devel's Garden lava Bed, Squaw Ridge Lava Bed, and Four Craters Lava Bed Wilderness Study Areas include approximately 70,940 acres and are underlain entirely by Pleistocene or Holocene lava flows and associated sediments. There is no evidence of hydrothermal alteration in the study areas. No resources were identified in the study areas, but there is low potential for perlite resources in the southern part of the Devil's Garden Lava Bed and the northern half of the Squaw Ridge Lava Bed areas. All three study areas have low potential for geothermal resources and for oil and gas resources.

  8. Incipient sympatric speciation in Midas cichlid fish from the youngest and one of the smallest crater lakes in Nicaragua due to differential use of the benthic and limnetic habitats?

    PubMed

    Kautt, Andreas F; Machado-Schiaffino, Gonzalo; Torres-Dowdall, Julian; Meyer, Axel

    2016-08-01

    Understanding how speciation can occur without geographic isolation remains a central objective in evolutionary biology. Generally, some form of disruptive selection and assortative mating are necessary for sympatric speciation to occur. Disruptive selection can arise from intraspecific competition for resources. If this competition leads to the differential use of habitats and variation in relevant traits is genetically determined, then assortative mating can be an automatic consequence (i.e., habitat isolation). In this study, we caught Midas cichlid fish from the limnetic (middle of the lake) and benthic (shore) habitats of Crater Lake Asososca Managua to test whether some of the necessary conditions for sympatric speciation due to intraspecific competition and habitat isolation are given. Lake As. Managua is very small (<900 m in diameter), extremely young (maximally 1245 years of age), and completely isolated. It is inhabited by, probably, only a single endemic species of Midas cichlids, Amphilophus tolteca. We found that fish from the limnetic habitat were more elongated than fish collected from the benthic habitat, as would be predicted from ecomorphological considerations. Stable isotope analyses confirmed that the former also exhibit a more limnetic lifestyle than the latter. Furthermore, split-brood design experiments in the laboratory suggest that phenotypic plasticity is unlikely to explain much of the observed differences in body elongation that we observed in the field. Yet, neutral markers (microsatellites) did not reveal any genetic clustering in the population. Interestingly, demographic inferences based on RAD-seq data suggest that the apparent lack of genetic differentiation at neutral markers could simply be due to a lack of time, as intraspecific competition may only have begun a few hundred generations ago. PMID:27551387

  9. Crater Rim

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    The late afternoon sun casts a shadow over a 700 meter-high rim of Huygens Crater.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

    Image information: VIS instrument. Latitude -15.2, Longitude 51.6 East (308.4 West). 19 meter/pixel resolution.

  10. Becquerel Crater

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03676 Linear Clouds

    This interesting deposit is located on the floor of Becquerel Crater.

    Image information: VIS instrument. Latitude 21.3N, Longitude 352.2E. 18 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  11. Impact Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    [figure removed for brevity, see original site]

    The layering of material observed at the bottom of this impact crater suggests multiple depositional and erosional episodes in a changing environment.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Crater-lake Santa Maria del Oro as a Pristine Reference for Persistent Organic Pollutants (POP' s) and Heavy Metals Content in Environmental Investigations in Western Mexico (Project Conacyt-Semarnat 2002-C01-0463, in Progress).

    NASA Astrophysics Data System (ADS)

    Zarate-Del Valle, P. F.; Gomez-Hermosillo, C. M.; Venegas-Garcia, D. J.

    2007-12-01

    Santa Maria del Oro Lake ( SMO) (21.37° N, 104.57° W; 750 m a.s.l.) is a quaternary crater-lake located at western Mexico in the natural border between two geological provinces: the plio-quaternary Trans-Mexican Volcanic Belt and the oligo-miocenic silicic volcanic province Sierra Madre Occidental. SMO, a tropical freshwater lake, is a warm-monomictic lake having a diameter of ca. 2 km and a mean depth at the depocenter of ca. 60 m, where three benthos cores were recovered. Contents of POP' s, total inorganic carbon (TIC), total organic carbon (TOC) and heavy metals were analyzed. Geochemistry and mineralogy also were studied in shallow sediments which corresponded to the decade of 50-60's, otherwise the beginning of industrial development of central Mexico; which is considered the possible source of emission of POP' s and heavy metals. Dioxin, furan, plaguicides and PCB' s contents were analyzed by a GC-MS applying USEPA methods. In the first 40 cm (n= 20) of the sedimentary column ( SC) the absence of POP' s was evidenced, applying a method detection limit ( MDL) of 5 μ g/ml for dioxin, furan and PCB' s. For plaguicides like chlordane and toxaphene the MDL was 0.5 μ g/ml and for plaguicides like DDT, aldrin, endrin, dieldrin, heptachlore and mirex the MDL was 5 μ g/ml. The MDL for HCB was 1 μ g/ml. The average (n= 30) for TIC, TOC and total carbon (TC) for the first 40 cm of the SC is as follows: TIC 2.4 %, TOC 3.7 % and TC 6.12 %. The average (n= 20) content (in ppm) of heavy metals for the first 20 cm of the SC is as follows: As 5.97, Cr 27.54, Cu 16.31, Ni 12.29, Pb 21.35 and Zn 82.46. These contents are roughly similar to the clarke of these metals in volcanic rocks. After the criteria of severe effect level ( SEL) of heavy metal in sediments, the content of these metals is below SEL levels. These results permit us to conclude that the sediments of SMO can be considered in unaffected state with respect to antropogenic contamination like POP' s and heavy

  13. A Rare Window Into Magmatic Conduit Processes: Time Series Observations From Active Lava Lakes

    NASA Astrophysics Data System (ADS)

    Lev, E.; Ruprecht, P.; Patrick, M.; Oppenheimer, C.; Peters, N.; Spampinato, L.; Hernandez Perez, P. A.; Unglert, K.; Barreyre, T.

    2015-12-01

    Time-lapse thermal images of the lake surface are used to investigate the circulation and cooling patterns of three lava lakes: Kilauea's Halema'uma'u crater, Mount Erebus, and Nyiragongo. We report results for the time-dependent, two-dimensional velocity and temperature fields of the lake surface. These data sets constrain the locations of flow divergence (upwelling) and convergence (downwelling), the distribution of distinct "plates" and "rifts", the dominant time scales for changes in flow pattern at each lake, and the physical properties of the magma. Upwelling and downwelling locations are strikingly different between the three lakes. Upwelling at Nyiragongo and Erebus occurs dominantly in the interior of the lake, where it is occasionally interrupted by catastrophic downwellings. At Halema'uma'u upwelling and downwelling occur consistently along the perimeter. It remains to be seen whether these differences are dictated merely by the system's geometry or are indicative of intrinsic factors such as melt viscosity, temperature and volatile and crystal content, or of conduit processes such as gas pistoning or slug flow. The availability of high resolution data at Halema'uma'u allows as us to document the evolution of crustal plates and rifts and to investigate the physical properties of the lava and the crust. The physical properties of the lake's surface control lake cooling rates, and thus need to be included in lake circulation and thermal evolution models. We produce time-temperature cooling curves from surface temperature profiles normal to surface rifts and by tracking the cooling of intra-plate bubble bursts. By comparing observations to analytical cooling models, we estimate a porosity of > 80% during the high stand of the lake, slightly higher than estimates of 70% for the upper 120 meters based on gravity data, and close to the porosity of clasts ejected from the lake during recent minor explosions. Furthermore,we find that the number of surface plates

  14. Past, present and future of volcanic lake monitoring

    NASA Astrophysics Data System (ADS)

    Rouwet, Dmitri; Tassi, Franco; Mora-Amador, Raúl; Sandri, Laura; Chiarini, Veronica

    2014-02-01

    Volcanic lake research boosted after lethal gas burst occurred at Lake Nyos (Cameroon) in 1986, a limnic rather than a volcanic event. This led to the foundation of the IAVCEI-Commission on Volcanic Lakes, which grew out into a multi-disciplinary scientific community since the 1990s. We here introduce the first data base of volcanic lakes VOLADA, containing 474 lakes, a number that, in our opinion, is surprisingly high. VOLADA could become an interactive, open-access working tool where our community can rely on in the future. Many of the compiled lakes were almost unknown, or at least unstudied to date, whereas there are acidic crater lakes topping active magmatic-hydrothermal systems that are continuously or discontinuously monitored, providing useful information for volcanic surveillance (e.g., Ruapehu, Yugama, Poás). Nyos-type lakes, i.e. those hosted in quiescent volcanoes and characterized by significant gas accumulation in bottom waters, are potentially hazardous. These lakes tend to remain stably stratified in tropical and sub-tropical climates (meromictic), leading to long-term build-up of gas, which can be released after a trigger. Some of the unstudied lakes are possibly in the latter situation. Acidic crater lakes are easily recognized as active, whereas Nyos-type lakes can only be recognized as potentially hazardous if bottom waters are investigated, a less obvious operation. In this review, research strategies are lined out, especially for the “active crater lakes”. We make suggestions for monitoring frequency based on the principle of the “residence time dependent monitoring time window”. A complementary, multi-disciplinary (geochemistry, geophysics, limnology, statistics) approach is considered to provide new ideas, which can be the bases for future volcanic lake monitoring. More profound deterministic knowledge (e.g., precursory signals for phreatic eruptions, or lake roll-over events) should not only serve to enhance conceptual models of

  15. Ground-based thermal imaging of lava lakes at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Calkins, J.; Oppenheimer, C.; Kyle, P. R.

    2008-11-01

    Mount Erebus, a large intraplate stratovolcano dominating Ross Island, Antarctica, hosts the world's only active phonolite lava lakes. The main manifestation of activity at Erebus volcano in December 2004 was as the presence of two convecting lava lakes within an inner crater. The long-lived Ray Lake, ~ 1400 m 2 in area, was the site of up to 10 small Strombolian eruptions per day. A new but short-lived, ~ 1000-1200 m 2 lake formed at Werner vent in December 2004 sourced by lava flowing from a crater formed in 1993 by a phreatic eruption. We measured the radiative heat flux from the two lakes in December 2004 using a compact infrared (IR) imaging camera. Daily thermal IR surveys from the Main Crater rim provide images of the lava lake surface temperatures and identify sites of upwelling and downwelling. The radiative heat outputs calculated for the Ray and Werner Lakes are 30-35 MW and 20 MW, respectively. We estimate that the magma flux needed to sustain the combined heat loss is ~ 250-710 kg s - 1 , that the minimum volume of the magma reservoir is 2 km 3, and that the radius of the conduit feeding the Ray lake is ~ 2 m.

  16. Martian Meteor Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    20 February 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fairly young meteor impact crater on Mars that is about the same size ( 1 kilometer; 0.62 miles) as the famous Meteor Crater in northern Arizona, U.S.A. Like the Arizona crater, boulders of ejected bedrock can be seen on the crater's ejecta blanket and in the crater itself. This crater is located in the Aethiopis region of Mars near 4.7oN, 224.1oW. Sunlight illuminates the scene from the lower left.

  17. Carbon sources and biogeochemical processes in Monticchio maar lakes, Mt Vulture volcano (southern Italy): New geochemical constrains of active degassing of mantle derived fluids

    NASA Astrophysics Data System (ADS)

    Caracausi, A.; Nuccio, P. M.; Favara, R.; Grassa, F.

    2012-04-01

    Since the catastrophic releases of carbon dioxide from the African volcanic lakes Nyos and Monoun in the 1980s, the scientific community draw attention towards all those crater lakes able to accumulate massive amount of CO2, which could be catastrophically released following overturn of their deep waters. This implies a quantification of the gas accumulation rate into the lakes and the knowledge of recharge processes and their evolution in time. In fact the gaseous recharge in a lake occurs at alarming rates, when an active degassing of hazardous nature volatiles occurs into the lakes and the structure and dynamic of the lake permit the accumulation of gases into the water. The Monticchio lakes, LPM and LGM, occupies two maar craters formed during the last volcanic activity of Mt. Vulture occurred ˜ 140 000 years ago. LPM is a permanently stratified lake, with a thick deep volume of stagnant water and a shallower layer affected by seasonal overturn. On the contrary LGM is a monomittic lake with a complete overturn of the water during winter time. The major dissolved volatiles are methane and CO2. Dissolved helium is in trace amounts and its isotopic signature ranges between 6.1 and 5.3 Ra (Ra is the atmospheric 3He/4He isotopic ratio). These values are within the range of those measured in the olivine fluid inclusions (both of mantle xenoliths and dispersed in the pyroclastics) of LPM maar ejecta. During three years of investigations we observed that dissolved methane in the deep waters of LGM drastically decreases in wintertime as consequence of the complete overturn of the water. The isotopic signature of methane in the deepest portions of LGM (both sediment and water) is quite stable with time and highlights a biogenic origin, being produced both by acetate fermentation and by CO2-reduction in variable proportions. In contrast, a higher contribution of methane produced via CO2 reduction characterizes sediments at shallower depths. At LPM, there is a great

  18. Meteorite Impact Lakes: Difficulties of the Evidence for Origin

    NASA Astrophysics Data System (ADS)

    Sapelko, Tatyana; Naumenko, Mikhail; Kuznetsov, Denis

    2014-05-01

    In addition to volcanic and tectonic activity on the border of the Late Pleistocene and Holocene occurred and other disastrous events that are reflected in the history of the lakes. The recognition of meteorite impact crater lakes is impeded by difficulties in finding evidence of an impact origin. Such lakes have been recognized (Hartung and Koeberl, 1994) by their circular shape, their occurrence outside of areas where other mechanisms for circular depression formation are readily apparent, and the preservation of meteorite or ejected glass fragments (Cohen. 2003). Meteorite impact Lake appeared not only in early periods (like Lake El'gygytgyn and Lake Yanisyarvi in Russia), but in the Late Pleistocene and Holocene as well. One of these lakes is located in the Nizhny Novgorod region of Russia. Svetloyar (56º49' N; 45º05'E; 109 m a.s.l.) - lake with a small area of 0.15 km2 and a great depth of the lake up to 35 m., a circular shape, surrounded on three sides by hills , reaching 15 m above the lake level. On the lake we have carried out paleolimnological and hydrological investigations.Interdisciplinary researches included sedimentological, geochemical, pollen, diatom, radiocarbon and other analyses of lake sediments. Based on field measurements, we created a digital morphometric model of the bottom depths and slopes of the lake. Using the all results we are reconstruct the Lake's history and climatic changes. We establish a long hiatus after the disappearance of large lake on the border of the late Pleistocene and Holocene. For comparison we were have studied three of the morphometric similar lakes in the Nizhny Novgorod region. According to preliminary data the history of any of these lakes is not similar the Lake Svetloyar history. We discuss our results and have compared with data on the meteorite Lake Kaali , Estonia (Rasmussen et al., 2000; Raukas et.al,1995; 2002; Veski et.al, 2001, 2002, 2004).

  19. Iturralde Crater, Bolivia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA scientists will venture into an isolated part of the Bolivian Amazon to try and uncover the origin of a 5 mile (8 kilometer) diameter crater there known as the Iturralde Crater. Traveling to this inhospitable forest setting, the Iturralde Crater Expedition 2002 will seek to determine if the unusual circular crater was created by a meteor or comet. Organized by Dr. Peter Wasilewski of NASA's Goddard Space Flight Center, Greenbelt, Md., the Iturralde Crater Expedition 2002 will be led by Dr. Tim Killeen of Conservation International, which is based in Bolivia. Killeen will be assisted by Dr. Compton Tucker of Goddard. The team intends to collect and analyze rocks and soil, look for glass particles that develop from meteor impacts and study magnetic properties in the area to determine if the Iturralde site was indeed created by a meteor.

    This image was acquired on June 29, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products.

    The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats; monitoring potentially active volcanoes; identifying crop stress; determining cloud morphology and physical properties; wetlands evaluation

  20. Crater studies: Part A: lunar crater morphometry

    USGS Publications Warehouse

    Pike, Richard J.

    1973-01-01

    Morphometry, the quantitative study of shape, complements the visual observation and photointerpretation in analyzing the most outstanding landforms of the Moon, its craters (refs. 32-1 and 32-2). All three of these interpretative tools, which were developed throughout the long history of telescopic lunar study preceding the Apollo Program, will continue to be applicable to crater analysis until detailed field work becomes possible. Although no large (>17.5 km diameter) craters were examined in situ on any of the Apollo landings, the photographs acquired from the command modules will markedly strengthen results of less direct investigations of the craters. For morphometry, the most useful materials are the orbital metric and panoramic photographs from the final three Apollo missions. These photographs permit preparation of contour maps, topographic profiles, and other numerical data that accurately portray for the first time the surface geometry of lunar craters of all sizes. Interpretations of craters no longer need be compromised by inadequate topographic data. In the pre-Apollo era, hypotheses for the genesis of lunar craters usually were constructed without any numerical descriptive data. Such speculations will have little credibility unless supported by accurate, quantitative data, especially those generated from Apollo orbital photographs. This paper presents a general study of the surface geometry of 25 far-side craters and a more detailed study of rim-crest evenness for 15 near-side and far-side craters. Analysis of this preliminary sample of Apollo 15 and 17 data, which includes craters between 1.5 and 275 km in diameter, suggests that most genetic interpretations of craters made from pre-Apollo topographic measurements may require no drastic revision. All measurements were made from topographic profiles generated on a stereoplotter at the Photogrammetric Unit of the U.S. Geological Survey, Center of Astrogeology, Flagstaff, Arizona.

  1. Aniakchak Crater, Alaska Peninsula

    USGS Publications Warehouse

    Smith, Walter R.

    1925-01-01

    The discovery of a gigantic crater northwest of Aniakchak Bay (see fig. 11) closes what had been thought to be a wide gap in the extensive series of volcanoes occurring at irregular intervals for nearly 600 miles along the axial line of the Alaska Peninsula and the Aleutian Islands. In this belt there are more active and recently active volcanoes than in all the rest of North America. Exclusive of those on the west side of Cook Inlet, which, however, belong to the same group, this belt contains at least 42 active or well-preserved volcanoes and about half as many mountains suspected or reported to be volcanoes. The locations of some of these mountains and the hot springs on the Alaska Peninsula and the Aleutian Islands are shown on a map prepared by G. A. Waring. Attention has been called to these volcanoes for nearly two centuries, but a record of their activity since the discovery of Alaska is far from being complete, and an adequate description of them as a group has never been written. Owing to their recent activity or unusual scenic beauty, some of the best known of the group are Mounts Katmai, Bogoslof, and Shishaldin, but there are many other beautiful and interesting cones and craters.

  2. Antoniadi Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    This false color image shows part of the floor of Antoniadi Crater. This image was collected during the Northern Spring season.

    Image information: VIS instrument. Latitude 37, Longitude 62.6 East (297.4 West). 35 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science

  3. Rampart Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 20 May 2004 This image of a rampart crater was acquired Dec. 6, 2002, during northern summer.

    The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 28.4, Longitude 319.2 East (40.8 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The

  4. Moreux Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 27 May 2004 This image of material entering Moreux Crater from the rim area was acquired March 17, 2003, during northern summer.

    The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 41.1, Longitude 44.1 East (315.9 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of

  5. Crater Ejecta

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 21 May 2004 This image of ejecta (top-left) from a rampart crater was acquired March 3, 2003, during northern summer.

    The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 25.9, Longitude 322 East (38 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science

  6. Sulfhydrolase activity in sediments of wintergreen lake, kalamazoo county, michigan.

    PubMed

    King, G M; Klug, M J

    1980-05-01

    The hydrolysis of p-nitrophenyl sulfate, p-nitrocatechol sulfate, and [S]sodium dodecyl sulfate was examined in anoxic sediments of Wintergreen Lake, Michigan. Significant levels of sulfhydrolase activity were observed in littoral, transition, and profundal sediment samples. Rates of sulfate formation suggest that the sulfhydrolase system would represent a major source of sulfate within these sediments. Sulfate formed by ester sulfate hydrolysis can support dissimilatory sulfate reduction as shown by the incorporation of S from labeled sodium dodecyl sulfate into H(2)S. Sulfhydrolase activity varied with sediment depth, was greatest in the littoral zone, and was sensitive to the presence of oxygen. Estimations of ester sulfate concentrations in sediments revealed large quantities of ester sulfate ( approximately 30% of total sulfur). Both total sulfur and ester sulfate concentrations varied with the sediment type and were two to three orders of magnitude greater than the inorganic sulfur concentration. PMID:16345573

  7. ASTER Observations of 2000-2007 Thermal Features at Pavlof Volcano and Mt. Hague (Emmons Lake Volcanic Center), Alaska

    NASA Astrophysics Data System (ADS)

    Wessels, R. L.; Schneider, D.; Ramsey, M.; Mangan, M. T.

    2007-12-01

    Emmons Lake Volcanic Center (ELVC) is a 15 km by 30 km area of nested calderas, stratovolcanoes, lava domes, hyaloclastite rings, and cinder cones aligned along the arc axis. Pavlof Volcano is the most active volcano along the ELVC, with more than 40 historic eruptions since 1790. The most recent eruption of Pavlof Volcano began in August 2007 after almost 11 years of quiescence. Mount Hague is a prominent intracaldera vent with no known historical eruptions that lies approximately 7 kilometers to the southwest of Pavlof. The southern crater of Mount Hague commonly fluctuates between a crater-filling lake to a dry crater floor with vigorously steaming fumaroles. Mount Hague has another fumarole field on the southeast flank at nearly the same elevation as the crater floor. To better document the behavior of persistent thermal features at these remote volcanoes, we have compiled temperature and dimension data using a seven-year long time series of satellite data. Over 25 daytime and 40 nighttime clear thermal infrared (TIR) images (90 m resolution) from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) have recorded variations in the thermal activity at both volcanic vents since July 2000. All cloud-free ASTER TIR observations document persistent low- temperature features at both Pavlof Volcano and Mount Hague during this period. The size and temperature of each thermal feature varies throughout the study period. The data show that the 2518 m summit of Pavlof Volcano is occasionally snow-free in early summer whereas neighboring peaks at lower elevations are still snow-clad. FLIR data acquired near the summit of Pavlof in 2004 show that the majority of warm ground was at 20°C to 40°C. These warm areas commonly persist snow-free into the winter. Temperature variations observed at Mt Hague crater usually correlate to the size of the ephemeral crater lake. As the lake grows, the pixel-integrated ASTER TIR temperature increases. Measurements

  8. The Explorer's Guide to Impact Craters

    NASA Astrophysics Data System (ADS)

    Pierazzo, E.; Osinski, G.; Chuang, F.

    2004-12-01

    Impact cratering is a fundamental geologic process of our solar system. It competes with other processes, such as plate tectonics, volcanism, or fluvial, glacial and eolian activity, in shaping the surfaces of planetary bodies. In some cases, like the Moon and Mercury, impact craters are the dominant landform. On other planetary bodies impact craters are being continuously erased by the action of other geological processes, like volcanism on Io, erosion and plate tectonics on the Earth, tectonic and volcanic resurfacing on Venus, or ancient erosion periods on Mars. The study of crater populations is one of the principal tools for understanding the geologic history of a planetary surface. Among the general public, impact cratering has drawn wide attention through its portrayal in several Hollywood movies. Questions that are raised after watching these movies include: ``How do scientists learn about impact cratering?'', and ``What information do impact craters provide in understanding the evolution of a planetary surface?'' Fundamental approaches used by scientists to learn about impact cratering include field work at known terrestrial craters, remote sensing studies of craters on various solid surfaces of solar system bodies, and theoretical and laboratory studies using the known physics of impact cratering. We will provide students, science teachers, and the general public an opportunity to experience the scientific endeavor of understanding and exploring impact craters through a multi-level approach including images, videos, and rock samples. This type of interactive learning can also be made available to the general public in the form of a website, which can be addressed worldwide at any time.

  9. Automated Crater Delineation

    NASA Astrophysics Data System (ADS)

    Marques, J. S.; Pina, P.

    2015-05-01

    An algorithm to delineate impact craters based on Edge Maps and Dynamic Programming is presented. The global performance obtained on 1045 craters from Mars (5 m to about 200 km in diameter), achieved 96% of correct contour delineations.

  10. Cratering on Asteroids

    NASA Astrophysics Data System (ADS)

    Marchi, S.; Chapman, C. R.; Barnouin, O. S.; Richardson, J. E.; Vincent, J.-B.

    Impact craters are a ubiquitous feature of asteroid surfaces. On a local scale, small craters puncture the surface in a way similar to that observed on terrestrial planets and the Moon. At the opposite extreme, larger craters often approach the physical size of asteroids, thus globally affecting their shapes and surface properties. Crater measurements are a powerful means of investigation. Crater spatial and size distributions inform us of fundamental processes, such as asteroid collisional history. A paucity of craters, sometimes observed, may be diagnostic of mechanisms of erasure that are unique on low-gravity asteroids. Byproducts of impacts, such as ridges, troughs, and blocks, inform us of the bulk structure. In this chapter we review the major properties of crater populations on asteroids visited by spacecraft. In doing so we provide key examples to illustrate how craters affect the overall shape and can be used to constrain asteroid surface ages, bulk properties, and impact-driven surface evolution.

  11. Hydrothermal Occurrences in Gusev Crater

    NASA Astrophysics Data System (ADS)

    Ruff, S. W.; Farmer, J. D.; Milliken, R.; Mills, V. W.; Shock, E.

    2011-12-01

    Exploration of the Gusev crater landing site by the Spirit rover has revealed for the first time, in situ evidence of hydrothermal activity on Mars. Most compelling are eroded outcrops of opaline silica found adjacent to "Home Plate" [1], an eroded stack of volcaniclastic deposits stratigraphically overlain by a vesicular basalt unit [2]. Recent work [3] demonstrates that the silica outcrops occur in a stratiform unit that possibly surrounds Home Plate. The outcrops are dominated by opal-A with no evidence for diagenesis to other silica phases. No other hydrous or alteration phases have been identified within the outcrops; most notable is a lack of sulfur phases. The outcrops have porous and in some cases, brecciated microtextures. Taken together, these observations support the interpretation that the opaline silica outcrops were produced in a hot spring or perhaps geyser environment. In this context, they are silica sinter deposits precipitated from silica-rich hydrothermal fluids, possibly related to the volcanism that produced the Home Plate volcanic rocks. On Earth, debris aprons in which sinter is brecciated, reworked, and cemented, are common features of hot springs and geysers and are good analogs for the Martian deposits. An alternative hypothesis is that the silica resulted from acid-sulfate leaching of precursor rocks by fumarolic steam condensates. But stratigraphic, textural, and chemical observations tend to diminish this possibility [3]. We are conducting extensive laboratory and field investigations of silica from both hot spring/geyser and fumarole environments to understand the full range of mineralogical, chemical, textural, and morphological variations that accompany its production, in order to shed more light on the Home Plate occurrence. The recent discovery of abundant Mg-Fe carbonate (16-34 wt%) in outcrops named Comanche provides possible evidence for additional hydrothermal activity in Gusev [4]. However, the carbonate is hosted by olivine

  12. A discussion of 'Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?'

    NASA Technical Reports Server (NTRS)

    Roedder, Edwin

    1990-01-01

    This paper presents arguments against the statement made by Koeberl et al. (1989) to the effect that various differences between the quartz of the three quartz pebbles from the Roter Kamm impact crater (Namibia) and the quartz of the pegmatites present in the basement rocks of this crater can be best interpreted as evidence that the pebbles were formed (or 'recrystallized') by a post-impact hydrothermal system. Arguments are presented that suggest that the three quartz pebbles are, most likely, fragments of a preimpact vein quartz of hydrothermal origin.

  13. A discussion of 'Anomalous quartz from the Roter Kamm impact crater, Namibia - Evidence for post-impact hydrothermal activity?'

    NASA Astrophysics Data System (ADS)

    Roedder, Edwin

    1990-11-01

    This paper presents arguments against the statement made by Koeberl et al. (1989) to the effect that various differences between the quartz of the three quartz pebbles from the Roter Kamm impact crater (Namibia) and the quartz of the pegmatites present in the basement rocks of this crater can be best interpreted as evidence that the pebbles were formed (or 'recrystallized') by a post-impact hydrothermal system. Arguments are presented that suggest that the three quartz pebbles are, most likely, fragments of a preimpact vein quartz of hydrothermal origin.

  14. Distribution of Dehalococcoidia in the Anaerobic Deep Water of a Remote Meromictic Crater Lake and Detection of Dehalococcoidia-Derived Reductive Dehalogenase Homologous Genes.

    PubMed

    Biderre-Petit, Corinne; Dugat-Bony, Eric; Mege, Mickaël; Parisot, Nicolas; Adrian, Lorenz; Moné, Anne; Denonfoux, Jérémie; Peyretaillade, Eric; Debroas, Didier; Boucher, Delphine; Peyret, Pierre

    2016-01-01

    Here we describe the natural occurrence of bacteria of the class Dehalococcoidia (DEH) and their diversity at different depths in anoxic waters of a remote meromictic lake (Lake Pavin) using 16S rRNA gene amplicon sequencing and quantitative PCR. Detected DEH are phylogenetically diverse and the majority of 16S rRNA sequences have less than 91% similarity to previously isolated DEH 16S rRNA sequences. To predict the metabolic potential of detected DEH subgroups and to assess if they encode genes to transform halogenated compounds, we enriched DEH-affiliated genomic DNA by using a specific-gene capture method and probes against DEH-derived 16S rRNA genes, reductive dehalogenase genes and known insertion sequences. Two reductive dehalogenase homologous sequences were identified from DEH-enriched genomic DNA, and marker genes in the direct vicinity confirm that gene fragments were derived from DEH. The low sequence similarity with known reductive dehalogenase genes suggests yet-unknown catabolic potential in the anoxic zone of Lake Pavin. PMID:26734727

  15. Distribution of Dehalococcoidia in the Anaerobic Deep Water of a Remote Meromictic Crater Lake and Detection of Dehalococcoidia-Derived Reductive Dehalogenase Homologous Genes

    PubMed Central

    Biderre-Petit, Corinne; Dugat-Bony, Eric; Mege, Mickaël; Parisot, Nicolas; Adrian, Lorenz; Moné, Anne; Denonfoux, Jérémie; Peyretaillade, Eric; Debroas, Didier; Boucher, Delphine; Peyret, Pierre

    2016-01-01

    Here we describe the natural occurrence of bacteria of the class Dehalococcoidia (DEH) and their diversity at different depths in anoxic waters of a remote meromictic lake (Lake Pavin) using 16S rRNA gene amplicon sequencing and quantitative PCR. Detected DEH are phylogenetically diverse and the majority of 16S rRNA sequences have less than 91% similarity to previously isolated DEH 16S rRNA sequences. To predict the metabolic potential of detected DEH subgroups and to assess if they encode genes to transform halogenated compounds, we enriched DEH-affiliated genomic DNA by using a specific-gene capture method and probes against DEH-derived 16S rRNA genes, reductive dehalogenase genes and known insertion sequences. Two reductive dehalogenase homologous sequences were identified from DEH-enriched genomic DNA, and marker genes in the direct vicinity confirm that gene fragments were derived from DEH. The low sequence similarity with known reductive dehalogenase genes suggests yet-unknown catabolic potential in the anoxic zone of Lake Pavin. PMID:26734727

  16. Lake-level rise in the late Pleistocene and active subaquatic volcanism since the Holocene in Lake Kivu, East African Rift

    NASA Astrophysics Data System (ADS)

    Ross, Kelly Ann; Smets, Benoît; De Batist, Marc; Hilbe, Michael; Schmid, Martin; Anselmetti, Flavio S.

    2014-09-01

    The history of Lake Kivu is strongly linked to the activity of the Virunga volcanoes. Subaerial and subaquatic volcanoes, in addition to lake-level changes, shape the subaquatic morphologic and structural features in Lake Kivu's Main Basin. Previous studies revealed that volcanic eruptions blocked the former outlet of the lake to the north in the late Pleistocene, leading to a substantial rise in the lake level and subsequently the present-day thermohaline stratification. Additional studies have speculated that volcanic and seismic activities threaten to trigger a catastrophic release of the large amount of gases dissolved in the lake. The current study presents a bathymetric mapping and seismic profiling survey that covers the volcanically active area of the Main Basin at a resolution that is unprecedented for Lake Kivu. New geomorphologic features identified on the lake floor can accurately describe related lake-floor processes for the first time. The late Pleistocene lowstand is observed at 425 m depth, and volcanic cones, tuff rings, and lava flows observed above this level indicate both subaerial and subaquatic volcanic activities during the Holocene. The geomorphologic analysis yields new implications on the geologic processes that have shaped Lake Kivu's basin, and the presence of young volcanic features can be linked to the possibility of a lake overturn.

  17. Degraded Crater Rim

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 3 May 2002) The Science The eastern rim of this unnamed crater in Southern Arabia Terra is very degraded (beaten up). This indicates that this crater is very ancient and has been subjected to erosion and subsequent bombardment from other impactors such as asteroids and comets. One of these later (younger) craters is seen in the upper right of this image superimposed upon the older crater rim material. Note that this smaller younger crater rim is sharper and more intact than the older crater rim. This region is also mantled with a blanket of dust. This dust mantle causes the underlying topography to take on a more subdued appearance. The Story When you think of Arabia, you probably think of hot deserts and a lot of profitable oil reserves. On Mars, however, Southern Arabia Terra is a cold place of cratered terrain. This almost frothy-looking image is the badly battered edge of an ancient crater, which has suffered both erosion and bombardment from asteroids, comets, or other impacting bodies over the long course of its existence. A blanket of dust has also settled over the region, which gives the otherwise rugged landscape a soft and more subdued appearance. The small, round crater (upper left) seems almost gemlike in its setting against the larger crater ring. But this companionship is no easy romance. Whatever formed the small crater clearly whammed into the larger crater rim at some point, obliterating part of its edge. You can tell the small crater was formed after the first and more devastating impact, because it is laid over the other larger crater. How much younger is the small one? Well, its rim is also much sharper and more intact, which gives a sense that it is probably far more youthful than the very degraded, ancient crater.

  18. Impact craters on Titan

    USGS Publications Warehouse

    Wood, Charles A.; Lorenz, Ralph; Kirk, Randy; Lopes, Rosaly; Mitchell, Karl; Stofan, Ellen; Cassini RADAR Team

    2010-01-01

    Five certain impact craters and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain craters have morphologies similar to impact craters on rocky planets, as well as two with radar bright, jagged rims. The less certain craters often appear to be eroded versions of the certain ones. Titan's craters are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of craters implies that Titan's surface is quite young, but the modeled age depends on which published crater production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that craters with diameters smaller than about 35 km are younger than 200 million years old, and larger craters are older. Craters are not distributed uniformly; Xanadu has a crater density 2-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of craters on the leading hemisphere, and craters are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact craters, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact craters with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles.

  19. Impact craters on Titan

    USGS Publications Warehouse

    Wood, C.A.; Lorenz, R.; Kirk, R.; Lopes, R.; Mitchell, Ken; Stofan, E.

    2010-01-01

    Five certain impact craters and 44 additional nearly certain and probable ones have been identified on the 22% of Titan's surface imaged by Cassini's high-resolution radar through December 2007. The certain craters have morphologies similar to impact craters on rocky planets, as well as two with radar bright, jagged rims. The less certain craters often appear to be eroded versions of the certain ones. Titan's craters are modified by a variety of processes including fluvial erosion, mass wasting, burial by dunes and submergence in seas, but there is no compelling evidence of isostatic adjustments as on other icy moons, nor draping by thick atmospheric deposits. The paucity of craters implies that Titan's surface is quite young, but the modeled age depends on which published crater production rate is assumed. Using the model of Artemieva and Lunine (2005) suggests that craters with diameters smaller than about 35 km are younger than 200 million years old, and larger craters are older. Craters are not distributed uniformly; Xanadu has a crater density 2-9 times greater than the rest of Titan, and the density on equatorial dune areas is much lower than average. There is a small excess of craters on the leading hemisphere, and craters are deficient in the north polar region compared to the rest of the world. The youthful age of Titan overall, and the various erosional states of its likely impact craters, demonstrate that dynamic processes have destroyed most of the early history of the moon, and that multiple processes continue to strongly modify its surface. The existence of 24 possible impact craters with diameters less than 20 km appears consistent with the Ivanov, Basilevsky and Neukum (1997) model of the effectiveness of Titan's atmosphere in destroying most but not all small projectiles. ?? 2009 Elsevier Inc.

  20. Anaglyph, Manicouagan Crater, Quebec, Canada

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Manicouagan Crater is one of the world's largest and oldest known impact craters and perhaps the one most readily apparent to astronauts in orbit. The age of the impact is estimated at 214 million years before present. Since then erosion has removed about one kilometer (0.6 miles) of rock from the region and has created a topographic pattern that follows the structural pattern of the crater. A ring depression (prominently seen as dark gray) encloses a central peak. The ring depression now hosts the Manicouagan Reservoir and so appears as a distinct ring lake to astronauts and as a smooth and flat feature in this topographic visualization. A fine pattern of topographic striations trending south-southeast, most prominent within the crater itself, indicates the flow direction of glaciers that covered this area during the last ice age.

    This anaglyph is derived entirely from the SRTM elevation model. First a gray image was created that uses image brightness to represent a mix of topographic height (higher elevations are brighter) and topographic orientation (northern slopes are brighter). The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter. Total topographic relief from the ring lake level to the central crater peak is about 600 meters (2000 feet).

    Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. The mission used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar that flew twice on the Space Shuttle Endeavour in 1994. The Shuttle Radar Topography Mission was designed to collect three-dimensional measurements of the Earth

  1. DAN Active Parameters and Mastcam Hydration Survey Imaging: Comparisons Across Yellowknife Bay, Gale Crater, Mars

    NASA Astrophysics Data System (ADS)

    Hardgrove, C. J.; Rice, M. S.; Moersch, J.; Mitrofanov, I. G.; Litvak, M.; Wellington, D. F.; Behar, A.; Bell, J. F.; Boynton, W. V.; DeFlores, L.; Drake, D.; Fedosov, F.; Golovin, D.; Jun, I.; Harshman, K.; Kozyrev, A.; Malakhov, A.; Milliken, R.; Kuzmin, R.; Mischna, M. A.; Mokrousov, M.; Nikiforov, S.; Sanin, A.; Tate, C.; Team, M.

    2013-12-01

    is a buried layer of H-rich material more strongly influencing the DAN signal. Through modeling of a variety of layer geometries and H-rich layers, we investigate whether a one- or two-layer model more accurately fits the DAN data as well as the amount of H within each layer. As of sol 269, DAN has acquired over 30 active measurements while Curiosity made her way to the location of where the first and second drill holes would be made, including measurements at those sites. Over 100 Mastcam hydration survey observations within Yellowknife Bay have been acquired, primarily at the drill sites. We will present the results of detailed mapping of the veins and nodules within the Mastcam hydration surveys in Yellowknife Bay to determine if the DAN signal can be correlated or anti-correlated to the surficial spatial distribution of these features. Where data from other instruments like APXS or ChemCam are available to constrain the H or Cl abundance at the location of a given DAN active measurement, and if those compositions are assumed to be laterally homogeneous within the DAN footprint, they can be used to constrain the modeled surface compositions to determine how deep the surface composition extends.

  2. Venus - Lavinia Region Impact Craters

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Three large meteorite impact craters, with diameters that range from 37 to 50 kilometers (23 to 31 miles), are seen in this image of the Lavinia region of Venus. The image is centered at 27 degrees south latitude and 339 degrees east longitude (longitude on Venus is measured from 0 degrees to 360 degrees east), and covers an area 550 kilometers (342 miles) wide by about 500 kilometers (311 miles) long. Situated in a region of fractured plains, the craters show many features typical of meteorite impact craters, including rough (bright) material around the rim, terraced inner walls and central peaks. Numerous domes, probably caused by volcanic activity, are seen in the southeastern corner of the mosaic. The domes range in diameter from 1 to 12 kilometers (0.6 to 7 miles). Some of the domes have central pits that are typical of some types of volcanoes. North is at the top of the image.

  3. A Relationship Between Microbial Activity in Soils and Phosphate Levels in Tributaries to Lake Champlain

    NASA Astrophysics Data System (ADS)

    Larose, R.; Lee, S.; Lane, T.

    2015-12-01

    Lake Champlain is a large natural freshwater lake. It forms the western boundary of Vermont and drains over half of the state. It is bordered by the state of New York on its western side and drains to the north into Quebec, Canada. Lake Champlain is the source of fresh drinking water for over quarter of a million people and provides for the livelihoods and recreational opportunities of many well beyond its borders. The health of this lake is important. During the summer month's algae blooms plague the lake. These unsightly growths, which affect other aquatic organisms, are the result of excess phosphate flowing into the lake from many sources. Examining whether there is a relationship between microbial activity in the soils bordering tributaries to Lake Champlain and phosphate levels in those tributaries sheds insight into the origins and paths by which phosphate moves into Lake Champlain. Understanding the how phosphate moves into the water system may assist in mitigation efforts.Total Phosphate levels and Total Suspended Solids were measured in second and third order streams in the Lake Champlain Basin over a three-year period. In addition microbial activity was measured within the toe, bank and upland riparian zone areas of these streams during the summer months. In general in areas showing greater microbial activity in the soil(s) there were increased levels of phosphate in the streams.

  4. Becquerel Crater Deposit

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 28 May 2002) The finely layered deposit in Becquerel crater, seen in the center of this THEMIS image, is slowly being eroded away by the action of windblown sand. Dark sand from a source north of the bright deposit is collecting along its northern edge, forming impressive barchan style dunes. These vaguely boomerang-shaped dunes form with their two points extending in the downwind direction, demonstrating that the winds capable of moving sand grains come from the north. Grains that leave the dunes climb the eroding stair-stepped layers, collecting along the cliff faces before reaching the crest of the deposit. Once there, the sand grains are unimpeded and continue down the south side of the deposit without any significant accumulation until they fall off the steep cliffs of the southern margin. The boat-hull shaped mounds and ridges of bright material called yardangs form in response to the scouring action of the migrating sand. To the west, the deposit has thinned enough that the barchan dunes extend well into the deeply eroded north-south trending canyons. Sand that reaches the south side collects and reforms barchan dunes with the same orientation as those on the north side of the deposit. Note the abrupt transition between the bright material and the dark crater floor on the southern margin. Steep cliffs are present with no indication of rubble from the obvious erosion that produced them. The lack of debris at the base of the cliffs is evidence that the bright material is readily broken up into particles that can be transported away by the wind. The geological processes that are destroying the Becquerel crater deposit appear active today. But it is also possible that they are dormant, awaiting a particular set of climatic conditions that produces the right winds and perhaps even temperatures to allow the erosion to continue.

  5. Putative crater-floor pingos, paleolakes and periglacial landscapes in north Utopia Planitia, Mars.

    NASA Astrophysics Data System (ADS)

    Soare, R. J.; Conway, S. J.; Dohm, J. M.

    2012-04-01

    Pingos are perennial ice-cored (but non-glacial) hills or mounds. They evolve and persist only in continuous and deep permafrost, i.e. ground that is frozen for periods of no less than two years. In periglacial (or cold-climate, non-glacial) regions such as the Tuktoyaktuk Coastlands of northern Canada closed-system pingos originate where thermokarst lakes either have lost or are losing their water by drainage, evaporation or sublimation. Closed-system pingos form as a result of freeze-thaw cycling, permafrost aggradation and pore-water migration. If closed-system pingos were identified on Mars, particularly on late Amazonian terrain at near-polar latitudes, this would point to boundary-conditions of pressure and temperature at or above the triple point of water having occurred much more recently and closer to the polar regions than many workers have thought possible. In 2005, we found two crater-floor landscapes in northern Utopia Planitia with mounds that seemed to share a suite of morphological characteristics and landform associations with closed-system pingos on Earth (Soare et al. 2005). Since this study the HiRISE and CTX cameras on-board the Mars Reconnaissance Orbiter have provided better coverage and higher resolution images of the area, allowing us to refine our previous work. We have identified two additional craters with similar assemblages and have verified the absence of such assemblages in other craters across a circum-global longitudinal transect spanning 20 degrees (~52°-72° N) of latitude. This allows us to evaluate the closed-system pingo hypothesis anew. Interestingly, the four principal mound-bearing craters occur within a tight latitudinal band from ~64°-71° N. This could be a marker of active albeit highly localised hydrological and freeze-thaw cycling. Conway et al. (2011) have identified perennial ice-domes on impact-crater floors at latitudes (~70° N) that are adjacent to the mound-bearing craters. They hypothesise that the ice domes

  6. Martian doublet craters.

    NASA Technical Reports Server (NTRS)

    Oberbeck, V. R.; Aoyagi, M.

    1972-01-01

    A large number of Mars craters are nearly tangential to other craters. They occur in clusters or as isolated crater doublets. Results of probability calculations and a Monte Carlo cratering simulation model show conclusively that many of the Mars craters could not have resulted from random single-body impact. The possibility that these craters are calderas is considered possible only if calderas on Mars form by mechanisms different from those on earth. However, clusters and doublets could be caused by meteoroid breakup resulting from stresses induced in the meteoroid by the gravitational field of Mars. It is concluded that, under certain conditions, doublets should be produced on Mars as a direct result of breakup of an impacting meteoroid. The impact process can yield nonrandom crater distributions that should be observed in different degrees of development on different planetary surfaces.

  7. Marine-target craters on Mars? An assessment study

    USGS Publications Warehouse

    Ormo, J.; Dohm, J.M.; Ferris, J.C.; Lepinette, A.; Fairen, A.G.

    2004-01-01

    Observations of impact craters on Earth show that a water column at the target strongly influences lithology and morphology of the resultant crater. The degree of influence varies with the target water depth and impactor diameter. Morphological features detectable in satellite imagery include a concentric shape with an inner crater inset within a shallower outer crater, which is cut by gullies excavated by the resurge of water. In this study, we show that if oceans, large seas, and lakes existed on Mars for periods of time, marine-target craters must have formed. We make an assessment of the minimum and maximum amounts of such craters based on published data on water depths, extent, and duration of putative oceans within "contacts 1 and 2," cratering rate during the different oceanic phases, and computer modeling of minimum impactor diameters required to form long-lasting craters in the seafloor of the oceans. We also discuss the influence of erosion and sedimentation on the preservation and exposure of the craters. For an ocean within the smaller "contact 2" with a duration of 100,000 yr and the low present crater formation rate, only ???1-2 detectable marine-target craters would have formed. In a maximum estimate with a duration of 0.8 Gyr, as many as 1400 craters may have formed. An ocean within the larger "contact 1-Meridiani," with a duration of 100,000 yr, would not have received any seafloor craters despite the higher crater formation rate estimated before 3.5 Gyr. On the other hand, with a maximum duration of 0.8 Gyr, about 160 seafloor craters may have formed. However, terrestrial examples show that most marine-target craters may be covered by thick sediments. Ground penetrating radar surveys planned for the ESA Mars Express and NASA 2005 missions may reveal buried craters, though it is uncertain if the resolution will allow the detection of diagnostic features of marine-target craters. The implications regarding the discovery of marine-target craters on

  8. Activity levels of some radionuclides in Mariout and Brullus lakes, Egypt.

    PubMed

    Dar, Mahmoud A; El Saharty, Abeer A

    2013-11-01

    Mariout and Brullus are two of the highly fish-productive lakes in the northern coast of Egypt along the Mediterranean Sea. They are widely used to drain industrial wastes, sewage and agriculture drainage. The activities of (238)U, (232)Th, (40)K and (137)Cs were measured in the uppermost part of the surface sediments of the two lakes, using gamma-ray spectrophotometry. Brullus Lake recorded significantly higher (238)U and (232)Th and lower (40)K (17.22±2.49, 10.03±0.56 and 299.70±17.78 Bq kg(-1)) than Mariout Lake (12.65±1.53, 7.24±0.76 and 518.75±46.24 Bq kg(-1), respectively). Cesium-137 shows nearly equal activities in both lakes (3.33±0.46 and 3.68±0.70 Bq kg(-1), respectively). Activity distributions of (238)U and (232)Th in the sediments of Mariout Lake show a significant increase to the west, southwest and northeast, (40)K activity increased westwards, while the (137)Cs level was increased to the east and northeast, indicating agriculture drainage, industrial wastes and lands reclamation around the lake. At Brullus Lake, the activity trends of (238)U, (232)Th, (40)K and(137)Cs were increasing to the west and south towards the agriculture and industrial waste-water-feeding drains. PMID:23630385

  9. Gradational evolution of young, simple impact craters on the Earth

    NASA Technical Reports Server (NTRS)

    Grant, J. A.; Schultz, P. H.

    1991-01-01

    From these three craters, a first order gradational evolutionary sequence can be proposed. As crater rims are reduced by backwasting and downwasting through fluvial and mass wasting processes, craters are enlarged by approx. 10 pct. Enlargement of drainages inside the crater eventually forms rim breaches, thereby capturing headward portions of exterior drainages. At the same time, the relative importance of gradational processes may reverse on the ejecta: aeolian activity may supersede fluvial incisement and fan formation at late stages of modification. Despite actual high drainage densities on the crater exterior during early stages of gradation, the subtle scale of these systems results in low density estimates from air photos and satellite images. Because signatures developed on surfaces around all three craters appear to be mostly gradient dependent, they may not be unique to simple crater morphologies. Similar signatures may develop on portions of complex craters as well; however, important differences may also occur.

  10. Strong assortative mating by diet, color, size, and morphology but limited progress toward sympatric speciation in a classic example: Cameroon crater lake cichlids.

    PubMed

    Martin, Christopher H

    2013-07-01

    Models predict that sympatric speciation depends on restrictive parameter ranges, such as sufficiently strong disruptive selection and assortative mating, but compelling examples in nature have rarely been used to test these predictions. I measured the strength of assortative mating within a species complex of Tilapia in Lake Ejagham, Cameroon, a celebrated example of incipient sympatric adaptive radiation. This species complex is in the earliest stages of speciation: morphological and ecological divergence are incomplete, species differ primarily in breeding coloration, and introgression is common. I captured 27 mated pairs in situ and measured the diet, color, size, and morphology of each individual. I found strong assortative mating by color, size, head depth, and dietary source of benthic or pelagic prey along two independent dimensions of assortment. Thus, Ejagham Tilapia showed strong assortative mating most conducive to sympatric speciation. Nonetheless, in contrast to a morphologically bimodal Sarotherodon cichlid species pair in the lake, Ejagham Tilapia show more limited progress toward speciation, likely due to insufficient strength of disruptive selection on morphology estimated in a previous study (γ = 0.16). This supports the predicted dependence of sympatric speciation on strong assortment and strong disruptive selection by examining a potentially stalled example in nature. PMID:23815664

  11. Testing the potential of 10Be in varved sediments from two lakes for solar activity reconstruction

    NASA Astrophysics Data System (ADS)

    Czymzik, Markus; Muscheler, Raimund; Brauer, Achim; Adolphi, Florian; Ott, Florian; Kienel, Ulrike; Dräger, Nadine; Slowinski, Michal; Aldahan, Ala; Possnert, Göran

    2015-04-01

    The potential of 10Be in annually laminated (varved) lake sediments for solar activity reconstruction is, to date, largely unexplored. It is hypothesized that 10Be contents in sediments from well-chosen lakes reflect the solar induced atmospheric production signal. The varved nature of these archives provides the chance to establish solar activity time-series with very high temporal precision. However, so far solar activity reconstruction from 10Be in varved lake sediments is hampered due to a lack of detailed knowledge of the process chain from production in the atmosphere to deposition on the lake floor. Calibrating 10Be time-series from varved lake sediments against complementary proxy records from the same sediment archive as well as instrumental meteorological and solar activity data will allow a process-based understanding of 10Be deposition in these lakes and a quantitative evaluation of their potential for solar activity reconstruction. 10Be concentration and flux time-series at annual resolution were constructed for the period 1983 to 2007 (approx. solar cycles 22 and 23) conducting accelerator mass spectrometry and varve chronology on varved sediments of Lakes Tiefer See and Czechowski, located on an east-west transect at a distance of about 450 km in the lowlands of northern-central Europe. 10Be concentrations vary between 0.9 and 1.8*108atoms/g, with a mean of 1.3*108atoms/g in Lake Tiefer See and between 0.6 and 1.6*108atoms/g, with a mean of 1*108atoms/g in Lake Czechowski. Calculated mean 10Be flux is 2.3*108atoms/cm2/year for Lake Tiefer See and 0.7*108atoms/cm2/year for Lake Czechowski. Calibrating the 10Be time-series against corresponding geochemical μ-XRF profiles, varve thickness and total organic carbon records as well as precipitation data from the nearby stations Schwerin for Lake Tiefer See and Koscierzyna for Lake Czechowski and a neutron monitor record of solar activity suggests (1) a complex interaction of varying processes influencing

  12. Erosion Effects of Liquid Water and Volatiles in a Former Lacustrine Environment - From Gale Crater to Death Valley

    NASA Astrophysics Data System (ADS)

    Iacob, R. H.; Bonaccorsi, R.; Iacob, C. E.

    2014-12-01

    During its first two years of exploration, Curiosity rover provided strong evidence of water activity at Gale Crater on Mars. While liquid water is not commonly present on the surface of Mars, large depressions such as Gale Crater hold evidence that water was collected in impact craters on Mars in the distant past. Specific features such as alluvial fans, inverted riverbeds, moat areas, and sedimentary formations, demonstrate strong water activity on low elevation regions of Mars. While surface water (gradually) disappeared as the climate and atmosphere of Mars changed, important water deposits formed underground, either as sub-surface ice shelves, or in the form of hydrated minerals, as demonstrated by MER and MSL. Although the presence of water ice under the ancient lake bed at the foothills of Mount Sharp is still to be determined, the area explored so far by Curiosity exhibits erosion features that can help describe the history of water activity along billions of years, e.g., river streams, lacustrine sedimentation, and later cycles of evaporation, frosting and sublimation. This presentation features a comparative study of water erosion processes at Gale Crater on Mars and Death Valley (DV) on Earth, from ancient water flows and lacustrine environments, through evaporation, dryness, and cyclic frosting and sublimation. Groundwater deposits in Death Valley offer best opportunities to study the process of minerals hydration, as well as landforms related to underground water percolation and evaporation, similar to those discovered by Curiosity at Yellowknife Bay. Furthermore, sedimentary processes in lacustrine proximal settings similar to those argued for Mount Sharp, or seen at Gale Crater's floor, have been studied in several locations of DV. These include, but are not limited to, younger dry lake beds of former lakes Manly and Panamint, carved badland formations of Furnace Creek Lake (Zabriskie Point) and older Tertiary lacustrine and fanglomeratic deposits

  13. Centennial Scale Variations in Lake Productivity Linked to Solar Activity

    NASA Astrophysics Data System (ADS)

    Englebrecht, A.; Bhattacharyya, S.; Guilderson, T. P.; Ingram, L.; Byrne, R.

    2012-12-01

    Solar variations on both decadal and centennial timescales have been associated with climate phenomena (van Loon et al., 2004; Hodell et al., 2001; White et al., 1997). The energy received by the Earth at the peak of the solar cycle increases by <0.1%; so the question has remained of how this could be amplified to produce an observable climate response. Recent modeling shows that the response of the Earth's climate system to the 11-year solar cycle may be amplified through stratosphere and ocean feedbacks and has the potential to impact climate variability on a multidecadal to centennial timescales (Meehl et al., 2009). Here, we report a 1000-year record of changes in the stratigraphy and carbon isotope composition of varved lake sediment from Isla Isabela (22°N, 106°W) in the subtropical northeast Pacific. Stable carbon isotopes and carbonate stratigraphy can be used to infer surface productivity in the lake. Our analysis shows variations in primary productivity on centennial timescales and suggests that solar activity may be an important component of Pacific climate variability. A possible response during solar maxima acts to keep the eastern equatorial Pacific cooler and drier than usual, producing conditions similar to a La Niña event. In the region around Isla Isabela peak solar years were characterized by decreased surface temperatures and suppressed precipitation (Meehl et al., 2009), which enhance productivity at Isabela (Kienel et al. 2011). In the future, we plan to analyze the data using advanced time series analysis techniques like the wavelets together with techniques to handle irregularly spaced time series data. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-571672

  14. Active lakes in Antarctica survive on a sedimentary substrate - Part 1: Theory

    NASA Astrophysics Data System (ADS)

    Carter, S. P.; Fricker, H. A.; Siegfried, M. R.

    2015-03-01

    Over the past decade satellite observations have revealed that active subglacial lake systems are widespread under the Antarctic ice sheet, including the ice streams, yet we have insufficient understanding of the lake-drainage process to incorporate it into ice sheet models. Process models for drainage of ice-dammed lakes based on conventional "R-channels" incised into the base of the ice through melting are unable to reproduce the timing and magnitude of drainage from Antarctic subglacial lakes estimated from satellite altimetry given the low hydraulic gradients along which such lakes drain. We developed a process model in which channels are mechanically eroded into deformable subglacial sediment (till) instead ("T-channel"). When applied to the known lakes of the Whillans/Mercer system, the model successfully reproduced the key characteristics of estimated lake volume changes for the period 2003-2009. If our model is realistic, it implies that most active lakes are shallow and only exist in the presence of saturated sediment, explaining why they are difficult to detect with classical radar methods. It also implies that the lake-drainage process is sensitive to the composition and strength of the underlying till, suggesting that models could be improved with a realistic treatment of sediment - interfacial water exchange.

  15. 238U-230Th crystallization ages for the oldest domes of the Mono Craters, eastern California

    NASA Astrophysics Data System (ADS)

    Marcaida, M.; Vazquez, J. A.

    2014-12-01

    The Mono Craters volcanic chain is one of the youngest areas of rhyolitic volcanism in the Mono Lake-Long Valley region of eastern California. Located just south of Mono Lake, the Mono Craters comprise at least 28 individual domes and flows (numbered 3-30, north to south); however, the timing and frequency of eruptions remain poorly resolved. The earliest signs of volcanic activity are preserved as numerous tephra layers (Ashes 1-19, top to bottom) in the late Pleistocene Wilson Creek formation of ancestral Mono Lake, which indicate that rhyolitic volcanism from Mono Craters began by at least ca. 62 ka [1]. Although the current chronology indicates that most of the Mono Craters are younger than ca. 20 ka [2-4], similar compositions of titanomagnetite from both pumice and lava potentially correlate several Wilson Creek tephras to porphyritic biotite-bearing domes 11, 24, and 19 of the Mono Craters [5], suggesting that multiple domes in the Mono Craters chain reflect volcanism older than ca. 20 ka. Ash 3 is correlated to dome 11 based on similar ca. 20 ka ages and titanomagnetite compositions [6]. More recently, we performed ion microprobe 238U-230Th dating of unpolished rims of allanite and zircon from domes 24 and 19, yielding isochron ages of ca. 38 ka and ca. 42 ka, respectively. The age of dome 24 is consistent with the ca. 38 ka age of its potential correlative tephra layers [1, 5], indicating that dome 24 is likely the extrusive equivalent of Ashes 9-10. Dome 19 has titanomagnetite crystals with similar bimodal chemistry to titanomagnetites from Ash 15 [5]. The age of dome 19 is indistinguishable from the 238U-230Th age of Ash 15 [1], which erupted during a prominent geomagnetic excursion, originally designated as the "Mono Lake" excursion. Combining geochronological and titanomagnetite compositional data confirms that Ash 15 and its extrusive equivalent, dome 19, erupted during the Laschamp excursion. [1] Vazquez, J.A. and Lidzbarski, M.I. (2012) EPSL 357

  16. The relative influences of climate and volcanic activity on Holocene lake development inferred from a mountain lake in central Kamchatka

    NASA Astrophysics Data System (ADS)

    Self, A. E.; Klimaschewski, A.; Solovieva, N.; Jones, V. J.; Andrén, E.; Andreev, A. A.; Hammarlund, D.; Brooks, S. J.

    2015-11-01

    A sediment sequence was taken from a closed, high altitude lake (informal name Olive-backed Lake) in the central mountain range of Kamchatka, in the Russian Far East. The sequence was dated by radiocarbon and tephrochronology and used for multi-proxy analyses (chironomids, pollen, diatoms). Although the evolution of Beringian climate through the Holocene is primarily driven by global forcing mechanisms, regional controls, such as volcanic activity or vegetation dynamics, lead to a spatial heterogeneous response. This study aims to reconstruct past changes in the aquatic and terrestrial ecosystems and to separate the climate-driven response from a response to regional or localised environmental change. Radiocarbon dates from plant macrophytes gave a basal date of 7800 cal yr BP. Coring terminated in a tephra layer, so sedimentation at the lake started prior to this date, possibly in the early Holocene following local glacier retreat. Initially the catchment vegetation was dominated by Betula and Alnus woodland with a mosaic of open, wet, aquatic and semi-aquatic habitats. Between 7800 and 6000 cal yr BP the diatom-inferred lake water was pH 4.4-5.3 and chironomid and diatom assemblages in the lake were initially dominated by a small number of acidophilic/acid tolerant taxa. The frequency of Pinus pumila (Siberian dwarf pine) pollen increased from 5000 cal yr BP and threshold analysis indicates that P. pumila arrived in the catchment between 4200 and 3000 cal yr BP. Its range expansion was probably mediated by strengthening of the Aleutian Low pressure system and increased winter snowfall. The diatom-inferred pH reconstructions show that after an initial period of low pH, pH gradually increased from 5500 cal yr BP to pH 5.8 at 1500 cal yr BP. This trend of increasing pH through the Holocene is unusual in lake records, but the initially low pH may have resulted directly or indirectly from intense regional volcanic activity during the mid-Holocene. The chironomid

  17. Gas-emission crater in Central Yamal, West Siberia, Russia, a new permafrost feature

    NASA Astrophysics Data System (ADS)

    Leibman, Marina; Kizyakov, Alexandr; Khomutov, Artem; Dvornikov, Yury; Streletskaya, Irina; Gubarkov, Anatoly

    2016-04-01

    The Yamal crater is a hole funnel-shaped on top and cylinder-shaped down to the bottom, surrounded by a parapet. Field study of the crater included size measurements, photo- video-documentation of the feature and the surrounding environment, and geochemical sampling. The upper part of the geological section within the crater consisted of stratified icy sediments, underlain by almost pure stratified ice of nearly vertical orientation of the layers. The volume of discharged material (volume of the void of the crater) was 6 times larger than the volume of material in the parapet. The difference was due to a significant amount of ice exposed in the walls of the crater, emitted to the surface and melted there. Remote sensing data was processes and validated by field observations to reveal the date of crater formation, previous state of the surface, evolution of the crater and environmental conditions of the surrounding area. Crater formed between 9 October and 1 November 2013. The initial size derived from Digital Elevation Model (DEM) had diameter of the vegetated rim 25-29 m. It turned through a sharp bend into a cylinder with close to vertical sides and diameter 15-16 m. Depth of the hole was impossible to estimate from DEM because of no light reaching walls in the narrow hole. By the time of initial observation in July 2014, water was found at the depth exceeding 50 m below the rim. In November 2014 this depth was 26 m. By September 2015 almost all the crater was flooded, with water surface about 5 m below the rim. The plan dimensions of the crater increased dramatically from initial 25-29 to 47-54 m in 2015. Thus, it took two warm seasons to almost entirely fill in the crater. We suppose that during the next 1-2 years parapet will be entirely destroyed, and as a result the crater will look like an ordinary tundra lake. Excluding impossible and improbable versions of the crater's development, the authors conclude that the origin of this crater can be attributed to

  18. Simulated Craters on Venus

    NASA Technical Reports Server (NTRS)

    Zahnle, Kevin; Cuzzi, Jeffrey N. (Technical Monitor)

    1995-01-01

    The thick atmosphere of Venus prevents all but the largest impactors from cratering the surface. The number of small craters on Venus provides an interesting, and statistically significant test of models for the disruption and deceleration of impacting bodies. Here we compare Monte Carlo simulated crater distributions to the observed crater distribution on Venus. The simulation assumes: (1) a power law mass distribution for impactors of the form N(sub cum) alpha m (exp-b) where b=0.8; (2) isotropic incidence angles; (3) velocity at the top of the atmosphere of 20 kilometers per second (more realistic velocity distributions are also considered); (4) Schmidt-Housen crater scaling, modified such that only the normal component of the impact velocity contributes to cratering, and using crater slumping as parameterized (5) and modern populations (60% carbonaceous, 40% stone, 3% iron) and fluxes of asteroids. We use our previously developed model for the disruption and deceleration of large bodies striking thick planetary atmospheres to calculate the impact velocity at the surface as a function of impactor mass, incident velocity, and incident angle. We use a drag coefficient c(sub d) =1; other parameters are as described in Chyba et al. We set a low velocity cutoff of 500 meters per second on crater-forming impacts. Venus's craters are nicely matched by the simulated craters produced by 700 million years of striking asteroids. Shown for comparison are the simulated craters produced by incident comets over the same period, where for comets we have assumed b=0.7 and a flux at 10(exp 14) g 30% that of asteroids. Systematic uncertainties in crater scaling and crater slumping may make the surface age uncertain by a factor of two.

  19. Active Lakes of the Recovery Ice Stream, East Antarctica: A Bedrock-Controlled Subglacial Hydrological System

    NASA Astrophysics Data System (ADS)

    Fricker, H. A.; Scambos, T. A.; Bell, R. E.; Carter, S. P.

    2014-12-01

    A connected system of active sub-glacial lakes was revealed beneath the Recovery Ice Stream, East Antarctica by ICESat laser altimetry acquired from 2003 to 2008. Here we combine repeat-track analysis of ICESat (2003-2009), Operation IceBridge laser altimetry and radio-echo sounding (RES; 2011 and 2012), and MODIS image differencing (2009-2011) to learn more about the surface and bedrock topographic setting of the lakes and the constraints on water flow through the system. IceBridge data reveal a ~1500 m deep, ~1000 km long bedrock trough under the main trunk of Recovery Ice Stream. We extend the lake activity time series to 2012 for the three lower lakes using IceBridge data: one lake underwent a large deflation between 2009 and 2011; another lake, which had been continuously filling between 2003 and 2010, started to drain after 2011. Hydrologic connections among the lakes appear to be direct and responsive. We reproduce the lake activity using a simple subglacial water model. The hydrologic system beneath Recovery Ice Stream is controlled by unusually pronounced bedrock topography (and not ice surface topography, as is the case for most Antarctic systems studied to date). We discuss potential causes of non-steady hydrologic behavior in major Antarctic catchments.

  20. Terrestrial laser scanning observations of geomorphic changes and varying lava lake levels at Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Jones, Laura K.; Kyle, Philip R.; Oppenheimer, Clive; Frechette, Jedediah D.; Okal, Marianne H.

    2015-03-01

    A Terrestrial Laser Scanning (TLS) instrument was used to image the topography of the Main Crater at Erebus volcano each December in 2008, 2009, and 2010. Our high-spatial resolution TLS scans provide unique insights into annual and decadal scale geomorphic evolution of the summit area when integrated with comparable data collected by an airborne instrument in 2001. We observe both a pattern of subsidence within the Inner Crater of the volcano and an ~ 3 m per-year drop in the lava lake level over the same time period that are suggestive of decreasing overpressure in an underlying magma reservoir. We also scanned the active phonolite lava lake hosted within the Inner Crater, and recorded rapid cyclic fluctuations in the level of the lake. These were sporadically interrupted by minor explosions by bursting gas bubbles at the lake surface. The TLS data permit calculation of lake level rise and fall speeds and associated rates of volumetric change within the lake. These new observations, when considered with prior determinations of rates of lake surface motion and gas output, are indicative of unsteady magma flow in the conduit and its associated variability in gas volume fraction.

  1. Impact crater degradation on venusian plains

    NASA Astrophysics Data System (ADS)

    Izenberg, N. R.; Arvidson, R. E.; Phillips, R. J.

    1994-02-01

    In venusian plains, impact craters without extensive low backscatter ejecta deposits are more likely to have low backscatter floors, be embayed by volcanic deposits, and exhibit fractures as compared to craters with extensive low backscatter ejecta. We interpret these trends as evidence of ongoing degradation of low backscatter ejecta by aeolian activity, weathering, and volcanism. Using a crater age sequence based on extent of preservation of low backscatter ejecta, together with Monte Carlo simulations, we find that tectonic activity has extended over a longer time period than volcanism.

  2. Layers in Crater Cluster

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-431, 24 July 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a cluster of old, small impact craters near 36.3oN, 281.9oW. The group of craters was probably formed by secondary impacts following a much larger impact that occurred some distance away; the material that created these craters would have been the ejecta from the larger crater, rather than meteoroids from outer space. The craters cluster is considered to be relatively old because none of the craters have ejecta blankets any more, and each was filled, or partially filled, with layered material that was later eroded to form the terraced mounds found in their floors. This picture is illuminated from the lower left.

  3. Testing Crater Counting Assumptions with the Cratered Terrain Evolution Model

    NASA Astrophysics Data System (ADS)

    Minton, D. A.; Richardson, J. E.; Fassett, C. I.

    2015-05-01

    Using CTEM to answer the questions; 1) How close to Poisson-distributed are crater count uncertainties? and 2) How does observed clustering in crater count densities of large craters relate to the changes in the impactor flux?

  4. Anthropogenic activities affecting Arreo Lake (N Spain) during the last 2500 years

    NASA Astrophysics Data System (ADS)

    Corella, J.; Valero-Garces, B. L.; Stefanova, I.; El Amrani, A.; Morellón, M.; Rico, E.; González-Sampériz, P.; Moreno-Caballud, A.; Giralt, S.; Sigro, J.

    2010-12-01

    Arreo Lake is a small (288 ha surface area) karstic lake 25 m deep located at the northwestern edge of the Ebro Basin (NE Spain). The integration of sedimentary facies, element geochemistry, mineralogy, and biological proxies (pollen and diatoms), together with a robust chronological model provided by 15 AMS radiocarbon dating, 137Cs analyses, and varve counting, permitted a reconstruction of the main phases of anthropogenic activity affecting the Arreo Lake dynamic in the context of the climate variability in the Iberian Peninsula during the last two millennia. A high-resolution study of the lacustrine facies and diatoms, combined with their detailed comparison with recent regional instrumental climatic data (1952-2007), limnological monitoring of the lake (1992-2008), and recent land-use changes affecting the lake watershed show the strong influence of human activities in lake dynamics during the last 60 years. The main impacts are a large increase in sediment delivery to the lake after the 1980s, fluctuations in lake level caused by water extraction for irrigation, and changes in the mixing status of the lake. Littoral and distal sediment cores record the long history of the use of natural resources (salt, water, forest and farming) and their significant impacts in the lake during the last 2500 years. Periods of higher anthropogenic activities linked to increased salt production in the nearby Salinas de Añana during the Roman Period and the Early Middle Ages were coincident with deforestation and increased sediment delivery to the lake. The Modern period was characterized by an abrupt increase in the sedimentation rate. Forest expansion and reduced clastic input to the lake were synchronous with documented depopulation of the area during the Late Middle Ages and the 20th century. The synergy between climate and human activities is shown by the correspondence of increased human pressure and more favourable climate conditions, such as it is recorded during the

  5. Meteor Crater, AZ

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The Barringer Meteorite Crater (also known as 'Meteor Crater') is a gigantic hole in the middle of the arid sandstone of the Arizona desert. A rim of smashed and jumbled boulders, some of them the size of small houses, rises 50 m above the level of the surrounding plain. The crater itself is nearly a 1500 m wide, and 180 m deep. When Europeans first discovered the crater, the plain around it was covered with chunks of meteoritic iron - over 30 tons of it, scattered over an area 12 to 15 km in diameter. Scientists now believe that the crater was created approximately 50,000 years ago. The meteorite which made it was composed almost entirely of nickel-iron, suggesting that it may have originated in the interior of a small planet. It was 50 m across, weighed roughly 300,000 tons, and was traveling at a speed of 65,000 km per hour. This ASTER 3-D perspective view was created by draping an ASTER bands 3-2-1image over a digital elevation model from the US Geological Survey National Elevation Dataset.

    This image was acquired on May 17, 2001 by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite. With its 14 spectral bands from the visible to the thermal infrared wavelength region, and its high spatial resolution of 15 to 90 meters (about 50 to 300 feet), ASTER will image Earth for the next 6 years to map and monitor the changing surface of our planet.

    ASTER is one of five Earth-observing instruments launched December 18,1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of Economy, Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, California, is the U.S. Science team leader; Bjorn Eng of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The Terra mission is part of NASA's Earth Science Enterprise, along

  6. Crater Rays on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This mosaic of Voyager 2 images taken July 9, 1979, shows a prominent rayed crater on Jupiter's icy moon, Ganymede. The view on the left is a monochrome image, and that on the right is the same scene shown in false color designed to accentuate the icy ejecta rays splashed out by the impact. This crater is about 150 km (93 miles) across. Like several other large craters in this scene, the rayed one has a central pit, whose origins remain speculative but may involve impact melting or solid-state fluidization of the icy crust. Bright crater rays on Ganymede, like those on our own Moon, are useful to geologists because they constitute a set of features that were laid across the moon's surface at a discrete point in time--thus they serve as time markers that can be used to establish the sequence of events that shaped Ganymede's surface. For instance, the crater rays appear to be painted over, hence are younger than, areas of grooved terrain (lower left quadrant), whereas a somewhat smaller crater at the center of the scene has icy ejecta that appears to bury (hence, post-dates) the large crater ray system. One can conclude that the grooved terrain formed first, then the large crater and its rays, and then the smaller crater and its fresh icy ejecta deposits.

  7. Calibration of transfer functions between phytolith, vegetation and climate for integration of grassland dynamics in vegetation models. Application to a 50,000 yr crater lake core in Tanzania.

    NASA Astrophysics Data System (ADS)

    Bremond, L.; Alexandre, A.; Hely, C.; Vincens, A.; Williamson, D.; Guiot, J.

    2004-12-01

    Global vegetation models provide a way to translate the outputs from climate models into maps of potential vegetation distribution for present, past and future. Validation of these models goes through the comparison between model outputs and vegetation proxies for well constrained past climatic periods. Grass-dominated biomes are widespread and numerous. This diversity is hardly mirrored by common proxies such as pollen, charcoal or carbon isotopes. Phytoliths are amorphous silica that precipitate in and/or between living plant cells. They are commonly used to trace grasslands dynamics. However, calibration between phytolith assemblages, vegetation, and climate parameters are scarce. This work introduces transfer functions between phytolith indices, inter-tropical grassland physiognomy, and bio-climatic data that will be available for model/data comparisons. The Iph phytolith index discriminates tall from short grass savannas in West Africa. A transfer function allows to estimate evapo-transpiration AET/PET. The Ic phytolith index accurately estimates the proportion of Pooideae and Panicoideae grass sub-families, and potentially the C4/C3 grass dominance on East African mountains. The D/P index appears as a good proxy of Leaf Area Index (LAI) in tropical areas. These environmental parameters are commonly used as vegetation model outputs, but have been, up to now, hardly estimated by vegetation proxies. These transfer functions are applied to a 50,000 yr phytolith sequence from a crater lake (9°S; 33°E Tanzania). The record is compared to the pollen vegetation reconstruction and confronted to simulations of the LPJ-GUESS vegetation model (Stitch et. al, 2003).

  8. The Magma Transport System of the Mono Craters, California

    NASA Astrophysics Data System (ADS)

    Johnson, M. R.; Putirka, K. D.

    2013-12-01

    The Mono Craters are a series of 28 volcanic domes, coulees, and craters, just 16 km north of Long Valley. The magmatic products of the Mono Craters include mostly small magmatic bodies, sills, and dikes set in a transtensional tectonic setting. New high-density sampling of the domes reveals a wider range of magma compositions than heretofore recognized, and thus reveals what is likely a more complex magmatic system, involving a greater number of batches of magma and a more complex magma storage/delivery system. Here, we present a model for the magma plumbing system based on space-composition patterns and preliminary estimates of crystallization temperatures and pressures based on olivine-, feldspar- and clinopyroxene-liquid equilibria. Whole rock analyses show three compositionally distinct batches of magma within the Mono Craters proper: a felsic (73-78.4% SiO2), intermediate (64.4-68% SiO2) and mafic (52.7-61% SiO2) group. The Mono Lake Islands (Paoha and Negit) fall into the intermediate group, but contain distinctly lower TiO2 and Fe2O3 at a given SiO2 compared to all other Mono Craters; on this basis, we surmise that the Paoha and Negit eruptions represent a distinct episode of magmatism that is not directly related to the magmatic activity that created the Mono Craters proper. The discontinuous nature of the three groups indicates that magma mixing, while evident to some degree within and between certain domes, did not encompass the entire range of compositions at any given time. The three groups, however, do form a rough linear trend, and some subsets of domes have compositions that fall on distinctly linear (if still discontinuous) trends that cannot be reproduced by fractional crystallization, but rather are indicative of magma mixing. Our high-density sampling also reveals interesting geographical patterns: for example, felsic magmas erupt throughout the entire Mono Craters chain, erupting at a wide range of temperatures, ranging from 650-995°C, but

  9. Intense magmatic degassing through the lake of Copahue volcano, 2013-2014

    NASA Astrophysics Data System (ADS)

    Tamburello, G.; Agusto, M.; Caselli, A.; Tassi, F.; Vaselli, O.; Calabrese, S.; Rouwet, D.; Capaccioni, B.; Di Napoli, R.; Cardellini, C.; Chiodini, G.; Bitetto, M.; Brusca, L.; Bellomo, S.; Aiuppa, A.

    2015-09-01

    Here we report on the first assessment of volatile fluxes from the hyperacid crater lake hosted within the summit crater of Copahue, a very active volcano on the Argentina-Chile border. Our observations were performed using a variety of in situ and remote sensing techniques during field campaigns in March 2013, when the crater hosted an active fumarole field, and in March 2014, when an acidic volcanic lake covered the fumarole field. In the latter campaign, we found that 566 to 1373 t d-1 of SO2 were being emitted from the lake in a plume that appeared largely invisible. This, combined with our derived bulk plume composition, was converted into flux of other volcanic species (H2O ~ 10989 t d-1, CO2 ~ 638 t d-1, HCl ~ 66 t d-1, H2 ~ 3.3 t d-1, and HBr ~ 0.05 t d-1). These levels of degassing, comparable to those seen at many open-vent degassing arc volcanoes, were surprisingly high for a volcano hosting a crater lake. Copahue's unusual degassing regime was also confirmed by the chemical composition of the plume that, although issuing from a hot (65°C) lake, preserves a close-to-magmatic signature. EQ3/6 models of gas-water-rock interaction in the lake were able to match observed compositions and demonstrated that magmatic gases emitted to the atmosphere were virtually unaffected by scrubbing of soluble (S and Cl) species. Finally, the derived large H2O flux (10,988 t d-1) suggested a mechanism in which magmatic gas stripping drove enhanced lake water evaporation, a process likely common to many degassing volcanic lakes worldwide.

  10. Shallow submarine hydrothermal activity with significant contribution of magmatic water producing talc chimneys in the Wakamiko Crater of Kagoshima Bay, southern Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Yamanaka, Toshiro; Maeto, Kotaro; Akashi, Hironori; Ishibashi, Jun-Ichiro; Miyoshi, Youko; Okamura, Kei; Noguchi, Takuroh; Kuwahara, Yoshihiro; Toki, Tomohiro; Tsunogai, Urumu; Ura, Tamaki; Nakatani, Takeshi; Maki, Toshihiro; Kubokawa, Kaoru; Chiba, Hitoshi

    2013-05-01

    Active hydrothermal venting from shallow seafloor (200-m depth) with talc chimneys has been discovered at the Wakamiko Crater floor in the Aira Caldera, southern Kyushu, Japan. The major chemical composition of the fluids suggests that the fluids are supplied from a single reservoir. The fluid is characterized by a low chloride concentration, low δD value, and a high δ18O value, suggesting that the endmember hydrothermal fluid is a mixture of seawater and andesitic water and possibly contribution of meteoric water and/or phase separation. Such noticeable magmatic input may be supported by high helium isotopic ratio (6.77 RA) of fumarolic gas discharging from the crater. Silica and alkaline geothermometers indicate that the fluid-rock interaction in the reservoir occurs in the temperature range of 230 to 250 °C. The high alkalinity and high ammonium and dissolved organic matter concentrations in the fluid indicate interaction of the fluid with organic matter in sedimentary layers. At least three hydrothermal vents have been observed in the crater. Two of these have similar cone-shaped chimneys. The chimneys have a unique mineralogy and consist dominantly of talc (kerolite and hydrated talc) with lesser amounts of carbonate (dolomite and magnesite), anhydrite, amorphous silica, and stibnite. The precipitation temperature estimated from δ18O values of talc was almost consistent with the observed fluid temperature. Geochemical modeling calculations also support the formation of talc and carbonate upon mixing of the endmember hydrothermal fluid with seawater and suggest that the talc chimneys are currently growing from venting fluid.

  11. Experimental impact crater morphology

    NASA Astrophysics Data System (ADS)

    Dufresne, A.; Poelchau, M. H.; Hoerth, T.; Schaefer, F.; Thoma, K.; Deutsch, A.; Kenkmann, T.

    2012-04-01

    The research group MEMIN (Multidisciplinary Experimental and Impact Modelling Research Network) is conducting impact experiments into porous sandstones, examining, among other parameters, the influence of target pore-space saturation with water, and projectile velocity, density and mass, on the cratering process. The high-velocity (2.5-7.8 km/s) impact experiments were carried out at the two-stage light-gas gun facilities of the Fraunhofer Institute EMI (Germany) using steel, iron meteorite (Campo del Cielo IAB), and aluminium projectiles with Seeberg Sandstone as targets. The primary objectives of this study within MEMIN are to provide detailed morphometric data of the experimental craters, and to identify trends and characteristics specific to a given impact parameter. Generally, all craters, regardless of impact conditions, have an inner depression within a highly fragile, white-coloured centre, an outer spallation (i.e. tensile failure) zone, and areas of arrested spallation (i.e. spall fragments that were not completely dislodged from the target) at the crater rim. Within this general morphological framework, distinct trends and differences in crater dimensions and morphological characteristics are identified. With increasing impact velocity, the volume of craters in dry targets increases by a factor of ~4 when doubling velocity. At identical impact conditions (steel projectiles, ~5km/s), craters in dry and wet sandstone targets differ significantly in that "wet" craters are up to 76% larger in volume, have depth-diameter ratios generally below 0.19 (whereas dry craters are almost consistently above this value) at significantly larger diameters, and their spallation zone morphologies show very different characteristics. In dry craters, the spall zone surfaces dip evenly at 10-20° towards the crater centre. In wet craters, on the other hand, they consist of slightly convex slopes of 10-35° adjacent to the inner depression, and of sub-horizontal tensile

  12. Katabatically Driven Downslope Windstorm-Type Flows on the Inner Sidewall of Arizona's Barringer Meteorite Crater

    NASA Astrophysics Data System (ADS)

    Whiteman, C. D.; Lehner, M.; Hoch, S.; Hills, M.; Haiden, T.; Feigenwinter, I.; Grudzielanek, M.; Maric, M.; Kalthoff, N.; Vogt, R.; Cermak, J.; Rotunno, R.; Calhoun, R.; Cherukuru, N.; Adler, B.

    2015-12-01

    The second Meteor Crater Experiment (METCRAX II) conducted in October 2013 at Arizona's Barringer Meteorite Crater investigated hydraulic-analogue atmospheric flows that cascade into the crater basin over its southwest rim. These intruding downslope windstorm-type flows are produced when the depth of the temperature inversion and accompanying southwesterly downslope flow on the surrounding gently sloping plain exceeds the height of the crater rim. As the southwesterly katabatic flow approaches the crater it decelerates, splits around the crater at elevations below the crater rim, and cascades over the crater rim at upper elevations. The intruding cold katabatic air accelerates down the inner sidewall of the crater, perturbing the prexisting shallow inversion on the crater floor, sometimes creating the atmospheric equivalent of ocean or lake basin seiches. When the cold air intrusions are strong, warm air is brought down into the crater from the upwind atmosphere above the mesoscale inversion, and hydraulic jumps may form on the southwest side of the crater while leaving the rest of the crater atmosphere relatively undisturbed. In this talk, evidence for these flow features will be presented, featuring dual Doppler and time-lapse IR animations of the intruding flows.

  13. BASALT 1: Extravehicular Activity Science Operations Concepts under Communication Latency and Bandwidth Constraints at Craters of the Moon, Idaho

    NASA Technical Reports Server (NTRS)

    Chappell, Steven P.; Beaton, Kara; Miller, Matthew J.; Lim, Darlene S. S.; Abercromby, Andrew F. J.

    2017-01-01

    An over-arching goal of the multi-year Biologic Analog Science Associated with Lava Terrains (BASALT) project is to iteratively develop, implement, and evaluate concepts of operations (ConOps) and supporting capabilities intended to enable and enhance human exploration of Mars. Geological and biological scientific fieldwork is being conducted during four total deployments at two high-fidelity Mars analogs, all within simulated Mars mission conditions that are based on current architectural assumptions for Mars exploration missions. Specific capabilities being evaluated include the use of mobile science platforms, extravehicular informatics, communication and navigation packages, advanced science mission planning tools, and scientifically-relevant instrument packages to achieve the project goals. This paper describes the planning, execution, and results of the first field deployment, referred to as BASALT 1, which consisted of a series of 12 simulated extravehicular activities (EVAs) on the lava terrains of Craters of the Moon, Idaho. Scientific objectives of the EVAs related to determination of how microbial communities and habitability correlate with the physical and geochemical characteristics of chemically-altered basalt environments. The concept of operations (ConOps) and capabilities deployed and tested during BASALT 1 were based on extensive data from previous NASA trade studies and analog testing, and the primary research question was whether those ConOps and capabilities would work acceptably when performing real (non-simulated) biological and geological scientific exploration under four different communication scenarios. Specifically, communication latencies of 5 and 15 minutes one-way light time (OWLT) were tested; these delays fall within the range of 4 to 22 minute OWLT delays that would be experienced during a Mars mission. Science operations were also conducted under low bandwidth conditions (0.512 Mb/s uplink, 1.54 Mb/s downlink), representing a

  14. 'Endurance Crater' Overview

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This overview of 'Endurance Crater' traces the path of the Mars Exploration Rover Opportunity from sol 94 (April 29, 2004) to sol 205 (August 21, 2004). The route charted to enter the crater was a bit circuitous, but well worth the extra care engineers took to ensure the rover's safety. On sol 94, Opportunity sat on the edge of this impressive, football field-sized crater while rover team members assessed the scene. After traversing around the 'Karatepe' region and past 'Burns Cliff,' the rover engineering team assessed the possibility of entering the crater. Careful analysis of the angles Opportunity would face, including testing an Earth-bound model on simulated martian terrain, led the team to decide against entering the crater at that particular place. Opportunity then backed up before finally dipping into the crater on its 130th sol (June 5, 2004). The rover has since made its way down the crater's inner slope, grinding, trenching and examining fascinating rocks and soil targets along the way. The rover nearly made it to the intriguing dunes at the bottom of the crater, but when it got close, the terrain did not look safe enough to cross.

  15. Degradation of selected terrestrial and Martian impact craters

    NASA Astrophysics Data System (ADS)

    Grant, J. A.; Schultz, P. H.

    1993-06-01

    The history of degradation of 50,000-yr-old 1.2-km-diam Meteor Crater in Arizona is defined using field mapping, and the degradation states of the progressively more degraded 68,000-yr-old 1.8-km-diam Lonar Crater in Indiana and 0.5-3.0 Myr old 1.75-km-diam Talemzane Crater in Algeria are assessed using air photos. The results on these terrestrial craters are then compared with the gradational morphology associated with craters in southern Ismenius Lacus on Mars, in order to develop first-order constraints on gradational activity. Common degradation signatures associated with craters on both planets are described. These signatures are used to assemble a first-order degradational sequence for the terrestrial craters that is then compared with the Martian degradational signatures to infer past processes and climate.

  16. Degradation of selected terrestrial and Martian impact craters

    NASA Technical Reports Server (NTRS)

    Grant, John A.; Schultz, Peter H.

    1993-01-01

    The history of degradation of 50,000-yr-old 1.2-km-diam Meteor Crater in Arizona is defined using field mapping, and the degradation states of the progressively more degraded 68,000-yr-old 1.8-km-diam Lonar Crater in Indiana and 0.5-3.0 Myr old 1.75-km-diam Talemzane Crater in Algeria are assessed using air photos. The results on these terrestrial craters are then compared with the gradational morphology associated with craters in southern Ismenius Lacus on Mars, in order to develop first-order constraints on gradational activity. Common degradation signatures associated with craters on both planets are described. These signatures are used to assemble a first-order degradational sequence for the terrestrial craters that is then compared with the Martian degradational signatures to infer past processes and climate.

  17. Centrifuge Impact Cratering Experiments

    NASA Technical Reports Server (NTRS)

    Schmidt, R. M.; Housen, K. R.; Bjorkman, M. D.

    1985-01-01

    The kinematics of crater growth, impact induced target flow fields and the generation of impact melt were determined. The feasibility of using scaling relationships for impact melt and crater dimensions to determine impactor size and velocity was studied. It is concluded that a coupling parameter determines both the quantity of melt and the crater dimensions for impact velocities greater than 10km/s. As a result impactor radius, a, or velocity, U cannot be determined individually, but only as a product in the form of a coupling parameter, delta U micron. The melt volume and crater volume scaling relations were applied to Brent crater. The transport of melt and the validity of the melt volume scaling relations are examined.

  18. Exhuming South Polar Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    7 February 2004 The large, circular feature in this image is an old meteor impact crater. The crater is larger than the 3 kilometers-wide (1.9 miles-wide) Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image, thus only part of the crater is seen. The bright mesas full of pits and holes--in some areas resembling swiss cheese--are composed of frozen carbon dioxide. In this summertime view, the mesa slopes and pit walls are darkened as sunlight causes some of the ice to sublime away. At one time in the past, the crater shown here may have been completely covered with carbon dioxide ice, but, over time, it has been exhumed as the ice sublimes a little bit more each summer. The crater is located near 86.8oS, 111.6oW. Sunlight illuminates this scene from the upper left.

  19. Temporal dynamics of active Archaea in oxygen-depleted zones of two deep lakes.

    PubMed

    Hugoni, Mylène; Domaizon, Isabelle; Taib, Najwa; Biderre-Petit, Corinne; Agogué, Hélène; Galand, Pierre E; Debroas, Didier; Mary, Isabelle

    2015-04-01

    Deep lakes are of specific interest in the study of archaeal assemblages as chemical stratification in the water column allows niche differentiation and distinct community structure. Active archaeal community and potential nitrifiers were investigated monthly over 1 year by pyrosequencing 16S rRNA transcripts and genes, and by quantification of archaeal amoA genes in two deep lakes. Our results showed that the active archaeal community patterns of spatial and temporal distribution were different between these lakes. The meromictic lake characterized by a stable redox gradient but variability in nutrient concentrations exhibited large temporal rearrangements of the dominant euryarchaeal phylotypes, suggesting a variety of ecological niches and dynamic archaeal communities in the hypolimnion of this lake. Conversely, Thaumarchaeota Marine Group I (MGI) largely dominated in the second lake where deeper water layers exhibited only short periods of complete anoxia and constant low ammonia concentrations. Investigations conducted on archaeal amoA transcripts abundance suggested that not all lacustrine Thaumarchaeota conduct the process of nitrification. A high number of 16S rRNA transcripts associated to crenarchaeal group C3 or the Miscellaneous Euryarchaeotic Group indicates the potential for these uncharacterized groups to contribute to nutrient cycling in lakes. PMID:25472601

  20. A history of the Lonar crater, India: An overview

    NASA Technical Reports Server (NTRS)

    Nayak, V. K.

    1992-01-01

    The origin of the circular structure at Lonar, India, described variously as cauldron, pit, hollow, depression, and crater, has been a controversial subject since the early nineteenth century. A history of its origin and other aspects from 1823 to 1990 are overviewed. The structure in the Deccan Trap Basalt is nearly circular with a breach in the northeast, 1830 m in diameter, 150 m deep, with a saline lake in the crater floor. Over the years, the origin of the Lonar structure has risen from volcanism, subsidence, and cryptovolcanism to an authentic meteorite impact crater. Lonar is unique because it is probably the only terrestrial crater in basalt and is the closest analog with the Moon's craters. Some unresolved questions are suggested. The proposal is made that the young Lonar impact crater, which is less than 50,000 years old, should be considered as the best crater laboratory analogous to those of the Moon, be treated as a global monument, and preserved for scientists to comprehend more about the mysteries of nature and impact cratering, which is now emerging as a fundamental ubiquitous geological process in the evolution of the planets.

  1. Duke on the Craters Edge

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut Charles M. Duke Jr., Lunar Module pilot of the Apollo 16 mission, is photographed collecting lunar samples at Station no. 1 during the first Apollo 16 extravehicular activity at the Descartes landing site. This picture, looking eastward, was taken by Astronaut John W. Young, commander. Duke is standing at the rim of Plum crater, which is 40 meters in diameter and 10 meters deep. The parked Lunar Roving Vehicle can be seen in the left background.

  2. The Water Volume Changes of Lake Manas and Its Response to Climate Change and Human Activities

    NASA Astrophysics Data System (ADS)

    Xu, Suning; Yang, Jingchun; Li, Youli

    2014-05-01

    The water volume changes of the lake basin in China's arid northwest region can sensitively reflect the impact of climate change and human activities in upper stream area. Lake Manas is a terminal lake of Manas Valley, a typical Valley in Northern Xinjiang. Just like other lakes, tectonic activities, such as water conservancy projects and agriculture irrigation projects, have great impacts on its evolution and change. We have a research on the response to climate change and human activities since 1950s, taking the Lake Manas for example. Collect aerial photographs and satellite imagery in year of 1958,1964,1979,1989,1999,2001,2003, with 1:50,000 topographic maps, 1:10000 DEM and other types of Figure and data of Lake Manas, we calculate the changes of the water volume of the Lake in 7different time period. According to the analysis of weather and hydrology records in the past 50 years, this author construct the correlation curves among the flow rate of Manas River, the temperature and precipitation in its upper steam area. This study shows that the development of contemporary Lake Manas could be divided to three stages: high-water period (in late the 1950s), extinct period (between 1970s and 1990s), and recovering season (in the early 21st century). The high-water period in late 1950s and the recovering season in early 21st century are mostly the results of excessive wet climate in the drainage basin, while the extinct period between the 1970s and the 1990s is mostly the result of man-made water projects in its upper stream area.The impact of climate change mainly in: the impact of climate change on runoff upstream determine the inflows of Lake Manas; the impact of downstream climate on the combination of water and heat determine the evaporation. The impact of human activities mainly in: the water conservancy projects upstream and agriculture irrigation projects since 1954 result in the extinct period between 1970s and 1990s in Lake Manas. Key Words: Lake Manas

  3. Impact Crater with Peak

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 14 June 2002) The Science This THEMIS visible image shows a classic example of a martian impact crater with a central peak. Central peaks are common in large, fresh craters on both Mars and the Moon. This peak formed during the extremely high-energy impact cratering event. In many martian craters the central peak has been either eroded or buried by later sedimentary processes, so the presence of a peak in this crater indicates that the crater is relatively young and has experienced little degradation. Observations of large craters on the Earth and the Moon, as well as computer modeling of the impact process, show that the central peak contains material brought from deep beneath the surface. The material exposed in these peaks will provide an excellent opportunity to study the composition of the martian interior using THEMIS multi-spectral infrared observations. The ejecta material around the crater can is well preserved, again indicating relatively little modification of this landform since its initial creation. The inner walls of this approximately 18 km diameter crater show complex slumping that likely occurred during the impact event. Since that time there has been some downslope movement of material to form the small chutes and gullies that can be seen on the inner crater wall. Small (50-100 m) mega-ripples composed of mobile material can be seen on the floor of the crater. Much of this material may have come from the walls of the crater itself, or may have been blown into the crater by the wind. The Story When a meteor smacked into the surface of Mars with extremely high energy, pow! Not only did it punch an 11-mile-wide crater in the smoother terrain, it created a central peak in the middle of the crater. This peak forms kind of on the 'rebound.' You can see this same effect if you drop a single drop of milk into a glass of milk. With craters, in the heat and fury of the impact, some of the land material can even liquefy. Central peaks like the one

  4. The Merna, Nebraska Meteorite Crater

    NASA Astrophysics Data System (ADS)

    Povenmire, H.

    1995-09-01

    significant raised rim. The nature of contour plowing would reduce any present rim by pulling the raised portion down into the crater. The crater has an average diameter of 5400 feet at the 2950 ft. elevation contour. The crater is elliptical with an eccentricity of approximately 0.71. It is oriented with the major axis at an azimuth of 45 degrees. The minimum age for this crater is approximately 3000 years as determined by one Carbon 14 sample [2]. This was probably a witnessed event as Pawnee Indian legends are rich in phenomena which may relate to this event. In the area surrounding the crater for several km are at least 12 secondary craters. Some of these have a diameter of 550 m. These are distinct from the eolian features by their circular shape and distribution from the primary crater. A 6.8 kg (H4) chondrite was found in the proximity [3]. It has a specific gravity of 3.5. Several magnetic spherules of probable extraterrestrial origin and large quantities of glass flakes have been found in the crater area. Approximately 60 quartz grains were examined by polarizing microscope and about half showed some shocking. There is an active search program for more meteorites in the area. A bore hole to search for breccia and shatter cones is planned. The "IMPACI" software was developed to simulate and model this projectile using the "average" entry velocity of Near Earth Asteroids of 21.8 km per second. The best solutions suggest an approximately 195 m diameter NEA entering the atmosphere and creating an air blast at approximately 8 km altitude. The kinetic energy would have been equivalent to 180 megatons of TNT of which approximately 50 percent would have been absorbed by the atmosphere [4] [5]. References: [1] Dort W. et al. (1992) GSA, 24, 196. [2] Dort W. (1993) personal communication. [3] Graham A. et al. (1985) Catalogue of Meteorites, 4th edition, p. 82, Univ. of Arizona. [4] Chyba C. et al. (1993) Nature, 361, 40-44. [5] Hills J. and Goda M. (1993) Astrophys. J., 105

  5. LAND USE ACTIVITIES AND WESTERN LAKE SUPERIOR WATER QUALITY

    EPA Science Inventory

    Geographic Information Systems (GlS), computer systems which can analyze mapped information, can help reduce nonpoint source pollution in the Lake Superior basin by providing researchers and managers with a tool for predicting the consequences of land use change. n an EPA-funded ...

  6. Venus - Mead Crater

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This Magellan image mosaic shows the largest (275 kilometers in diameter [170 miles]) impact crater known to exist on Venus at this point in the Magellan mission. The crater is located north of Aphrodite Terra and east of Eistla Regio at latitude 12.5 degrees north and longitude 57.4 degrees east, and was imaged during Magellan orbit 804 on November 12, 1990. The Magellan science team has proposed to name this crater Mead, after Margaret Mead, the American Anthropologist (1901- 1978). All Magellan-based names of features on Venus are, of course, only proposed until final approval is given by the International Astronomical Union-Commission on Planetary Nomenclature. Mead is classified as a multi-ring crater with its innermost, concentric scarp being interpreted as the rim of the original crater cavity. No inner peak-ring of mountain massifs is observed on Mead. The presence of hummocky, radar-bright crater ejecta crossing the radar-dark floor terrace and adjacent outer rim scarp suggests that the floor terrace is probably a giant rotated block that is concentric to, but lies outside of, the original crater cavity. The flat, somewhat brighter inner floor of Mead is interpreted to result from considerable infilling of the original crater cavity by impact melt and/or by volcanic lavas. To the southeast of the crater rim, emplacement of hummocky ejecta appears to have been impeded by the topography of preexisting ridges, thus suggesting a very low ground-hugging mode of deposition for this material. Radar illumination on this and all other Magellan image products is from the left to the right in the scene.

  7. Schroeter's ratios for Martian craters - Radar results

    NASA Astrophysics Data System (ADS)

    Roth, L. E.

    1991-01-01

    Schroeter's ratios (ratios of the rim volume to the apparent volume) are determined for a sample of 29 large, degraded Martian craters selected from the Goldstone Mars radar altimetry data. On the average, the values of the calculated Schroeter's ratios are about two orders of magnitude smaller than the same ratios for fresh lunar craters. This indicates a severe rim volume deficit in degraded Martian craters and it provides an additional support to the notion of a widespread resurfacing of intercrater plains on Mars. Schroeter's ratios for degraded craters could provide a semi-quantitative measure of the effects of the modification processes that had been active on Mars and on the other planetary bodies.

  8. Venus - Crater Aurelia

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This Magellan image shows a complex crater, 31.9 kilometers (20 miles) in diameter with a circular rim, terraced walls, and central peaks, located at 20.3 degrees north latitude and 331.8 degrees east longitude. Several unusual features are evidenced in this image: large dark surface up range from the crater; lobate flows emanating from crater ejecta, and very radar-bright ejecta and floor. Aurelia has been proposed to the International Astronomical Union, Subcommittee of Planetary Nomenclature as a candidate name. Aurelia is the mother of Julius Caesar.

  9. Crater with Streak

    NASA Technical Reports Server (NTRS)

    2005-01-01

    20 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater in the Memnonia region of Mars, around which has formed a wind streak. The bright streak is in the lee of the crater -- that is, it is on the crater's down-wind side. Thus, the winds responsible for the streak blew from the southeast (lower right).

    Location near: 6.7oS, 141.4oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  10. One View, Two Craters

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This cylindrical projection was constructed from a sequence of four images taken by the navigation camera onboard the Mars Exploration Rover Opportunity.

    The images were acquired on sol 85 of Opportunity's mission to Meridiani Planum. The camera acquired the images at approximately 14:28 local solar time, or around 6:30 a.m. Pacific Daylight Time, on April 20, 2004.

    The view is from the rover's new location, a region dubbed 'Fram Crater' located some 450 meters (.3 miles) from 'Eagle Crater' and roughly 250 meters (820 feet) from 'Endurance Crater' (upper right).

  11. Stratigraphy, mineralogy, and origin of layered deposits inside Terby crater, Mars

    NASA Astrophysics Data System (ADS)

    Ansan, V.; Loizeau, D.; Mangold, N.; Le Mouélic, S.; Carter, J.; Poulet, F.; Dromart, G.; Lucas, A.; Bibring, J.-P.; Gendrin, A.; Gondet, B.; Langevin, Y.; Masson, Ph.; Murchie, S.; Mustard, J. F.; Neukum, G.

    2011-01-01

    The 174 km diameter Terby impact crater (28.0°S-74.1°E) located on the northern rim of the Hellas basin displays anomalous inner morphology, including a flat floor and light-toned layered deposits. An analysis of these deposits was performed using multiple datasets from Mars Global Surveyor, Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter missions, with visible images for interpretation, near-infrared data for mineralogical mapping, and topography for geometry. The geometry of layered deposits was consistent with that of sediments that settled mainly in a sub-aqueous environment, during the Noachian period as determined by crater counts. To the north, the thickest sediments displayed sequences for fan deltas, as identified by 100 m to 1 km long clinoforms, as defined by horizontal beds passing to foreset beds dipping by 6-10° toward the center of the Terby crater. The identification of distinct sub-aqueous fan sequences, separated by unconformities and local wedges, showed the accumulation of sediments from prograding/onlapping depositional sequences, due to lake level and sediment supply variations. The mineralogy of several layers with hydrated minerals, including Fe/Mg phyllosilicates, supports this type of sedimentary environment. The volume of fan sediments was estimated as >5000 km 3 (a large amount considering classical martian fan deltas such as Eberswalde (6 km 3)) and requires sustained liquid water activity. Such a large sedimentary deposition in Terby crater is characteristic of the Noachian/Phyllosian period during which the environment favored the formation of phyllosilicates. The latter were detected by spectral data in the layered deposits of Terby crater in three distinct layer sequences. During the Hesperian period, the sediments experienced strong erosion, possibly enhanced by more acidic conditions, forming the current morphology with three mesas and closed depressions. Small fluvial valleys and alluvial fans formed subsequently

  12. Hydrothermal vents of Yellowstone Lake, Yellowstone National Park, Wyoming

    SciTech Connect

    Kaplinski, M.A.; Morgan, P. . Geology Dept.)

    1993-04-01

    Hydrothermal vent systems within Yellowstone Lake are located within the Yellowstone caldera in the northeastern and West Thumb sections of the lake. The vent systems lie within areas of extremely high geothermal gradients (< 1,000 C/km) in the lake sediments and occur as clusters of individual vents that expel both hydrothermal fluids and gas. Regions surrounding the vents are colonized by unique, chemotropic biologic communities and suggest that hydrothermal input plays an important role in the nutrient dynamics of the lake's ecosystem. The main concentration of hydrothermal activity occurs in the northeast region of the main lake body in a number of locations including: (1) along the shoreline from the southern edge of Sedge Bay to the inlet of Pelican Creek; (2) the central portion of the partially submerged Mary Bay phreatic explosion crater, within deep (30--50 m) fissures; (3) along the top of a 3 km long, steep-sided ridge that extends from the southern border of Mary Bay, south-southeast into the main lake basin; and (4) east of Stevenson Island along the lower portion of the slope (50--107 m) into the lake basin, within an anastomosing series of north to northwest trending, narrow troughs or fissures. Hydrothermal vents were also located within, and surrounding the West Thumb of Yellowstone Lake, with the main concentration occurring the offshore of the West Thumb and Potts Geyser Basin. Hydrothermal vents in Yellowstone Lake occur along fractures that have penetrated the lake sediments or along the tops of ridges and near shore areas. Underneath the lake, rising hydrothermal fluids encounter a semi-permeable cap of lake sediments. Upwardly convecting hydrothermal fluid flow may be diverted by the impermeable lake sediments along the buried, pre-existing topography. These fluids may continue to rise along topography until fractures are encountered, or the lake sediment cover is thinned sufficiently to allow egress of the fluids.

  13. Degradation of Victoria Crater, Meridiani Planum, Mars

    NASA Astrophysics Data System (ADS)

    Grant, J. A.; Wilson, S. A.; Cohen, B. A.; Golombek, M. P.; Geissler, P. E.; Sullivan, R. J.

    2007-12-01

    by aeolian erosion; thereby leading to mass wasting and accumulation of the large angular blocks observed on the slopes below By contrast, the shallow slope in the bays implies mass wasting is currently limited. Most likely, early mass wasting and aeolian stripping of the walls was gradually superseded by aeolian activity that proceeded most quickly along structural weaknesses and resulted in formation of the bays. Redistributed wall material contributes to crater infilling and/or was transported out of the crater. Occurrence of dark basaltic sands in the crater and in wind streaks along the north rim indicates additional transport into and out of the crater from other sources. The diminished expression of the rim, planed-off appearance of the ejecta blanket, paucity of exposed blocks, and dark wind streaks outside the crater imply efficient aeolian modification of Victoria crater, likely contributing to down-wasting and sediment transport that may be responsible for thin, local outcrops of finely bedded sediments capping the ejecta. The annulus appears to have resulted from combined erosion and planing of the ejecta, leading to evolution of a resistant lag of hematite concretions along with infilling and covering by the basaltic sand. There is no evidence for water-related erosional contributions to the present form of Victoria crater.

  14. The complex filling of alae crater, Kilauea Volcano, Hawaii

    USGS Publications Warehouse

    Swanson, D.A.; Duffield, W.A.; Jackson, D.B.; Peterson, D.W.

    1972-01-01

    Since February 1969 Alae Crater, a 165-m-deep pit crater on the east rift of Kilauea Volcano, has been completely filled with about 18 million m3 of lava. The filling was episodic and complex. It involved 13 major periods of addition of lava to the crater, including spectacular lava falls as high as 100 m, and three major periods of draining of lava from the crater. Alae was nearly filled by August 3, 1969, largely drained during a violent ground-cracking event on August 4, 1969, and then filled to the low point on its rim on October 10, 1969. From August 1970 to May 1971, the crater acted as a reservoir for lava that entered through subsurface tubes leading from the vent fissure 150 m away. Another tube system drained the crater and carried lava as far as the sea, 11 km to the south. Much of the lava entered Alae by invading the lava lake beneath its crust and buoying the crust upward. This process, together with the overall complexity of the filling, results in a highly complicated lava lake that would doubtless be misinterpreted if found in the fossil record. ?? 1972 Stabilimento Tipografico Francesco Giannini & Figli.

  15. Results From NICLAKES Survey of Active Faulting Beneath Lake Nicaragua, Central American Volcanic Arc

    NASA Astrophysics Data System (ADS)

    Funk, J.; Mann, P.; McIntosh, K.; Wulf, S.; Dull, R.; Perez, P.; Strauch, W.

    2006-12-01

    In May of 2006 we used a chartered ferry boat to collect 520 km of seismic data, 886 km of 3.5 kHz subbottom profiler data, and 35 cores from Lake Nicaragua. The lake covers an area of 7700 km2 within the active Central American volcanic arc, forms the largest lake in Central America, ranks as the twentieth largest freshwater lake in the world, and has never been previously surveyed or cored in a systematic manner. Two large stratovolcanoes occupy the central part of the lake: Concepcion is presently active, Maderas was last active less than 2000 years ago. Four zones of active faulting and doming of the lake floor were mapped with seismic and 3.5 kHz subbottom profiling. Two of the zones consist of 3-5-km-wide, 20-30-km-long asymmetric rift structures that trend towards the inactive cone of Maderas Volcano in a radial manner. The northeastern rift forms a 20-27-m deep depression on the lake bottom that is controlled by a north-dipping normal fault. The southwestern rift forms a 25-35-m deep depression controlled by a northeast-dipping normal fault. Both depressions contain mound-like features inferred to be hydrothermal deposits. Two zones of active faulting are associated with the active Concepcion stratovolcano. A 600-m-wide and 6-km-long fault bounded horst block extends westward beneath the lake from a promontory on the west side of the volcano. Like the two radial rift features of Maderas, the horst points roughly towards the active caldera of Concepcion. A second north-south zone of active faulting, which also forms a high, extends off the north coast of Concepcion and corresponds to a localized zone of folding and faulting mapped by previous workers and inferred by them to have formed by gravitational spreading of the flank of the volcano. The close spatial relation of these faults to the two volcanic cones in the lake suggests that the mechanism for faulting is a result of either crustal movements related to magma intrusion or gravitational sliding and is

  16. Living at the border: A community and single-cell assessment of lake bacterioneuston activity

    PubMed Central

    Hörtnagl, Paul; Pérez, María Teresa; Sommaruga, Ruben

    2010-01-01

    We assessed the physicochemical properties of the surface microlayer (SML: first 900 μm) and its underlying water (ULW: 0.2–0.5-m depth) and compared the composition and activity of their bacterial communities in six lakes located across an altitude gradient. Activity was assessed at both the community level, by measuring leucine bulk incorporation, and at the single-cell level, by using microautoradiography. Catalyzed reporter deposition fluorescence in situ hybridization was used to quantitatively assess the structure of the bacterial assemblage. Dissolved organic matter at the SML was significantly enriched in small-size molecules as compared to the ULW. Bacterial abundance in the SML ranged from 3.2 × 105 cells mL−1 to 3.2 × 106 cells mL−1 and was enriched in four out of six lakes when compared to the ULW. The SML and ULW showed lake-specific differences in bacterial community composition, although in most cases, both layers were dominated by Betaproteobacteria. This group also contributed the most to total activity in both layers in all lakes, followed by Actinobacteria. Despite large differences in environmental conditions among lakes, the fraction of active neustonic bacteria was very similar in most of them. Both bulk and single-cell activities are not necessarily lower in the SML than in the ULW, and well-adapted bacteria exist in the extreme conditions found in this habitat. PMID:20401318

  17. Rayed Gratteri Crater

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on image for larger version

    This HiRISE image covers the western portion of the primary cavity of Gratteri crater situated in the Memnonia Fossae region. Gratteri crater is one of five definitive large rayed craters on Mars. Gratteri crater has a diameter of approximately 6.9 kilometers. Crater rays are long, linear features formed from the high-velocity ejection of blocks of material that re-impact the surface in linear clusters or chains that appear to emanate from the main or primary cavity. Such craters have been long recognized as the 'brightest' and 'freshest' craters on the Moon. However, Martian rays differ from lunar rays in that they are not 'bright,' but best recognized by their thermal signature (at night) in 100 meter/pixel THEMIS thermal infrared images. The HiRISE image shows that Gratteri crater has well-developed and sharp crater morphologic features with no discernable superimposed impact craters. The HiRISE sub-image shows that this is true for the ejecta and crater floor up to the full resolution of the image. Massive slumped blocks of materials on the crater floor and the 'spur and gully' morphology with the crater wall may suggest that the subsurface in this area may be thick and homogenous. Gratteri crater's ejecta blanket (as seen in THEMIS images) can be described as 'fluidized,' which may be suggestive of the presence of ground-ice that may have helped to 'liquefy' the ejecta as it was deposited near the crater. Gratteri's ejecta can be observed to have flowed in and around obstacles including an older, degraded crater lying immediately to the SW of Gratteri's primary cavity.

    Image PSP_001367_1620 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 10, 2006. The complete image is centered at -17.7 degrees latitude, 199.9 degrees East longitude. The range to the target site was 257.1 km

  18. Shackleton Crater Illumination

    NASA Video Gallery

    Simulated illumination conditions near the lunar South Pole. The 30km x 30km region highlights the Shackleton crater. The movie runs for 28 days, centered on the LCROSS impact date on October 9th, ...

  19. Fresh, Rayed Impact Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-416, 9 July 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a fresh, young meteor impact crater on the martian surface. It is less than 400 meters (less than 400 yards) across. While there is no way to know the exact age of this or any other martian surface feature, the rays are very well preserved. On a planet where wind can modify surface features at the present time, a crater with rayed ejecta patterns must be very young indeed. Despite its apparent youth, the crater could still be many hundreds of thousands, if not several million, of years old. This impact scar is located within the much larger Crommelin Crater, near 5.6oN, 10.0oW. Sunlight illuminates the scene from the left.

  20. Craters and Streaks

    NASA Technical Reports Server (NTRS)

    2006-01-01

    1 April 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows two impact craters of nearly equal size, plus their associated wind streaks. These occur in far eastern Chryse Planitia. The wind streaks point toward the southwest (lower left), indicating that the responsible winds blew from the northeast. One of the two craters is shallower than the other, and has a suite of large, windblown ripples on its floor. The shallower crater with the ripples is probably older than the other, deeper crater.

    Location near: 20.6oN, 30.1oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  1. Craters and Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    11 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some typical relations between impact craters and light-toned, layered rock on Mars. The larger circular feature at the north (top) end of the image marks the location of a filled, buried crater on intermountain terrain north of Hellas Planitia. The larger crater at the southeast (lower right) corner formed by meteor impact into the layered material in which the buried crater is encased. The layered rock, in this case, has a light tone similar to the sedimentary rocks being explored by the Mars Exploration Rover, Opportunity, thousands of kilometers away in Sinus Meridiani.

    Location near: 24.9oS, 299.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  2. Patterns in benthic biodiversity link lake trophic status to structure and potential function of three large, deep lakes.

    PubMed

    Hayford, Barbara L; Caires, Andrea M; Chandra, Sudeep; Girdner, Scott F

    2015-01-01

    Relative to their scarcity, large, deep lakes support a large proportion of the world's freshwater species. This biodiversity is threatened by human development and is in need of conservation. Direct comparison of biodiversity is the basis of biological monitoring for conservation but is difficult to conduct between large, insular ecosystems. The objective of our study was to conduct such a comparison of benthic biodiversity between three of the world's largest lakes: Lake Tahoe, USA; Lake Hövsgöl, Mongolia; and Crater Lake, USA. We examined biodiversity of common benthic organism, the non-biting midges (Chironomidae) and determined lake trophic status using chironomid-based lake typology, tested whether community structure was similar between the three lakes despite geographic distance; and tested whether chironomid diversity would show significant variation within and between lakes. Typology analysis indicated that Lake Hövsgöl was ultra-oligotrophic, Crater Lake was oligotrophic, and Lake Tahoe was borderline oligotrophic/mesotrophic. These results were similar to traditional pelagic measures of lake trophic status for Lake Hövsgöl and Crater Lake but differed for Lake Tahoe, which has been designated as ultra-oligotrophic by traditional pelagic measures such as transparency found in the literature. Analysis of similarity showed that Lake Tahoe and Lake Hövsgöl chironomid communities were more similar to each other than either was to Crater Lake communities. Diversity varied between the three lakes and spatially within each lake. This research shows that chironomid communities from these large lakes were sensitive to trophic conditions. Chironomid communities were similar between the deep environments of Lake Hövsgöl and Lake Tahoe, indicating that chironomid communities from these lakes may be useful in comparing trophic state changes in large lakes. Spatial variation in Lake Tahoe's diversity is indicative of differential response of chironomid

  3. Walker Lake, Nevada: sedimentation in an active, strike-slip related basin

    SciTech Connect

    Link, M.H.; Roberts, M.T.

    1984-04-01

    Walker Lake, Nevada, is in an active fault-controlled basin related to the right-lateral, northwest-trending Walker Lane Shear Zone on the western side of the Basin and Range province. The lake occurs in a half graben bounded on its west side by a high-angle normal fault zone along the Wassuk Range front. This fault zone may merge to the north into the Walker Lane fault system, which forms the northeast boundary of the basin. To the south of Walker Lake, the Wassuk front fault merges with an east-northeast trending left-lateral fault. The Walker Lake basin is interpreted to be a pull-apart basin formed within the triangular zone bounded by the Wassuk front, the Walker Lane, and left-lateral faults. The Walker River drainage basin occupies about 10,000 km/sup 2/ (3800 mi/sup 2/) in western Nevada and parts of California and is essentially a closed hydrologic system that drains from the crest of the Sierra Nevada in California and terminates in Walker Lake. Walker Lake trends north-northwest and is 27.4 km (17 mi) long and 8 km (5 mi) wide with water depths exceeding 30 m (100 ft). Lake Lahontan (Wisconsinian) shorelines ring Walker Lake and suggest water depths of 150 m (500 ft) above the present lake level. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and gentle, areally more extensive fans flanking the eastern shoreline (Gillis Range). The Walker River delta enters the lake from the north and is a major sediment point source for the basin. Older dissected shoreline, alluvial fan, Gilbert delta, and beach ridge deposits were built largely of coarse-grained, locally derived materials. Stromatolites, oncolites, and tufas formed along the shorelines, whereas mud and organic sediments accumulated in the lake on the west side of the basin. Extensive submerged sand flats and local sand dunes occur on the east side of the basin.

  4. Cratering evaluations and results

    SciTech Connect

    Church, J.R.

    1993-08-01

    Investigations were performed on the 1-mil ultrasonic aluminum wire bonding process to determine how the interaction of the bonding parameters, ultrasonic power, time, force, and aluminum wire, contribute to cratering (cracking or damage to oxide/passivation layers). Investigations revealed that power, time, and force can interact at levels which can contribute to cratering. The age of the aluminum wire can also influence the quality of bonds.

  5. Har Crater on Callisto

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This image shows a heavily cratered region near Callisto's equator. It was taken by the Galileo spacecraft Solid State Imaging (CCD) system on its ninth orbit around Jupiter. North is to the top of the image. The 50 kilometer (30 mile) double ring crater in the center of the image is named Har. Har displays an unusual rounded mound on its floor. The origin of the mound is unclear but probably involves uplift of ice-rich materials from below, either as a 'rebound' immediately following the impact that formed the crater or as a later process. Har is older than the prominent 20 kilometer (12 mile) crater superposed on its western rim. The large crater partially visible in the northeast corner of the image is called Tindr. Chains of secondary craters (craters formed from the impact of materials thrown out of the main crater during an impact) originating from Tindr crosscut the eastern rim of Har.

    The image, centered at 3.3 degrees south latitude and 357.9 degrees west longitude, covers an area of 120 kilometers by 115 kilometers (75 miles by 70 miles). The sun illuminates the scene from the west (left). The smallest distinguishable features in the image are about 294 meters (973 feet) across. This image was obtained on June 25, 1997, when Galileo was 14,080 kilometers (8,590 miles) from Callisto.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  6. Zhamanshin meteor crater

    NASA Technical Reports Server (NTRS)

    Florenskiy, P. V.; Dabizha, A. I.

    1987-01-01

    A historical survey and geographic, geologic and geophysical characteristics, the results of many years of study of the Zhamanshin meteor crater in the Northern Aral region, are reported. From this data the likely initial configuration and cause of formation of the crater are reconstructed. Petrographic and mineralogical analyses are given of the brecciated and remelted rocks, of the zhamanshinites and irgizite tektites in particular. The impact melting, dispersion and quenching processes resulting in tektite formation are discussed.

  7. Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

    USGS Publications Warehouse

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska's interior. The water column CH4 oxidation potential for these shallow (~2m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes.

  8. Reconstruction of the geology and structure of Lake Rotomahana and its hydrothermal systems from high-resolution multibeam mapping and seismic surveys: Effects of the 1886 Tarawera Rift eruption

    NASA Astrophysics Data System (ADS)

    de Ronde, C. E. J.; Walker, S. L.; LeBlanc, C.; Davy, B. W.; Fornari, D. J.; Tontini, F. Caratori; Scott, B. J.; Seebeck, H.; Stewart, T. J.; Mazot, A.; Nicol, A.; Tivey, M. A.

    2016-03-01

    Present-day Lake Rotomahana is one of the two focal points of the most destructive eruption in New Zealand's historical record, i.e., that of Mt. Tarawera on 10 June 1886, with devastating loss of life and presumed destruction of the iconic Pink and White Terraces that adorned the margins of the lake. Basaltic dikes are considered to have ascended near surface in the area, intruding into hydrothermally altered and water-saturated ground beneath the existing lake. The consequential hydrothermal and phreatomagmatic eruptions ejected 0.5325 km3 of material from the lakefloor and below, plastering the nearby landscape for several kilometers with mud and other debris. The eruption buried the natural outlet of the lake, with the bottom of the craters becoming filled by water within months and completely concealed from view within years; today Lake Rotomahana has depths up to 118 m. High-resolution (0.5 m) bathymetric mapping, when combined with a 2-D seismic reflection survey, enables us to 'see' details of the maar craters on the lakefloor, including those parts subsequently buried by sediment. The large Rotomahana Crater described by workers immediately after the eruption measures ~ 2.5 km in diameter near its southwestern end, and excavated ground to 155 m below present-day lake level. The vent system, as revealed by the present study, forms an array of right-stepping (dextral) craters, with the main crater being host to two sub-craters Rotomahana West Crater and Rotomahana East Crater today buried beneath the lakefloor, and which are in-filled by 36 and 37 m of sediment, respectively. Subordinate craters along the same 057° Tarawera Rift trace include Hochstetter Crater (11 m of infill), Waingongongongo Crater (14 m) and Rotomakariri Crater (26 m). These craters host a total 0.0268 km3 of sediment. Other features highlighted by the bathymetric data include; craters not filled by sediment, sediment fan deltas, volcanic ridges and dikes, submerged wave-cut terraces

  9. Named Venusian craters

    NASA Technical Reports Server (NTRS)

    Russell, Joel F.; Schaber, Gerald G.

    1993-01-01

    Schaber et al. compiled a database of 841 craters on Venus, based on Magellan coverage of 89 percent of the planet's surface. That database, derived from coverage of approximately 98 percent of Venus' surface, has been expanded to 912 craters, ranging in diameter from 1.5 to 280 km. About 150 of the larger craters were previously identified by Pioneer Venus and Soviet Venera projects and subsequently formally named by the International Astronomical Union (IAU). Altogether, the crater names submitted to the IAU for approval to date number about 550, a little more than half of the number of craters identified on Magellan images. The IAU will consider more names as they are submitted for approval. Anyone--planetary scientist or layman--may submit names; however, candidate names must conform to IAU rules. The person to be honored must be deceased for at least three years, must not be a religious figure or a military or political figure of the 19th or 20th century, and, for Venus, must be a woman. All formally and provisionally approved names for Venusian impact craters, along with their latitude, longitude, size, and origin of their name, will be presented at LPSC and will be available as handouts.

  10. A Sourcebook of Marine Activities Developed in the Milwaukee Great Lakes Summer Education Program, 1977 and 1978.

    ERIC Educational Resources Information Center

    Haney, Richard E., Ed.

    Twenty-seven activities dealing with the marine environment of the Great Lakes are presented. Designed for junior and senior high school students, these activities develop awareness of the biological, physical, social, economical, and aesthetic dimensions of the Great Lakes. Field trips, films, discussion, and hands-on activities are used to teach…

  11. Exploration and discovery in Yellowstone Lake: Results from high-resolution sonar imaging, seismic reflection profiling, and submersible studies

    USGS Publications Warehouse

    Morgan, L.A.; Shanks, Wayne C.; Lovalvo, D.A.; Johnson, S.Y.; Stephenson, W.J.; Pierce, K.L.; Harlan, S.S.; Finn, C.A.; Lee, G.; Webring, M.; Schulze, B.; Duhn, J.; Sweeney, R.; Balistrieri, L.

    2003-01-01

    Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (???1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem. Published by Elsevier Science B.V.

  12. Exploration and discovery in Yellowstone Lake: results from high-resolution sonar imaging, seismic reflection profiling, and submersible studies

    NASA Astrophysics Data System (ADS)

    Morgan, L. A.; Shanks, W. C.; Lovalvo, D. A.; Johnson, S. Y.; Stephenson, W. J.; Pierce, K. L.; Harlan, S. S.; Finn, C. A.; Lee, G.; Webring, M.; Schulze, B.; Dühn, J.; Sweeney, R.; Balistrieri, L.

    2003-04-01

    'No portion of the American continent is perhaps so rich in wonders as the Yellow Stone' (F.V. Hayden, September 2, 1874) Discoveries from multi-beam sonar mapping and seismic reflection surveys of the northern, central, and West Thumb basins of Yellowstone Lake provide new insight into the extent of post-collapse volcanism and active hydrothermal processes occurring in a large lake environment above a large magma chamber. Yellowstone Lake has an irregular bottom covered with dozens of features directly related to hydrothermal, tectonic, volcanic, and sedimentary processes. Detailed bathymetric, seismic reflection, and magnetic evidence reveals that rhyolitic lava flows underlie much of Yellowstone Lake and exert fundamental control on lake bathymetry and localization of hydrothermal activity. Many previously unknown features have been identified and include over 250 hydrothermal vents, several very large (>500 m diameter) hydrothermal explosion craters, many small hydrothermal vent craters (˜1-200 m diameter), domed lacustrine sediments related to hydrothermal activity, elongate fissures cutting post-glacial sediments, siliceous hydrothermal spire structures, sublacustrine landslide deposits, submerged former shorelines, and a recently active graben. Sampling and observations with a submersible remotely operated vehicle confirm and extend our understanding of the identified features. Faults, fissures, hydrothermally inflated domal structures, hydrothermal explosion craters, and sublacustrine landslides constitute potentially significant geologic hazards. Toxic elements derived from hydrothermal processes also may significantly affect the Yellowstone ecosystem.

  13. Summit Explosive Activity and Deformation: Constraints On The Etna SE Crater Through Tilt Variations During The 1998-2000 Lava Fountains

    NASA Astrophysics Data System (ADS)

    Bonaccorso, A.

    We investigate the relationships between the strain expected from the explosive action of a volcanic conduit, the paroxystic lava fountain events occurring recently at Etna, and the high precision continuous tilt signals recorded during such events with refer- ence to the ones occurring at the SE crater. Using both the inclusion and dislocation theories, it has been shown that the displacements expected from the explosive action of the volcanic conduits are defined by an equation which includes a term proportional to a line dilatation integral plus an integral that subtracts the effects proportional to a line of vertical double forces. Then, from these equations, it is possible to obtain the expected tilt. We conducted a comparison and an analysis with the tilt signals recorded at the Pizzi Deneri (PDN) volcanological observatory located in the high north-eastern flank of Mt. Etna. Here, an 80 m long-base mercury tiltmeter is installed along two partially underground tunnels. The instrument, utilising optical laser sensors for mea- suring the level changes at the extremities, is very stable with a real precision of 0.01 microradians. At the PDN distance from crater, as expected from the conduit theory, deformation effects can be very small and difficult to detect even if provoked by strong explosions. Nevertheless, in particular situations during the paroxystic activity of the June 24, 2000 (violent explosive phase with only 30 minutes duration, instrumental sampling of 1 data/minute) we recorded small (0.1-0.2 microradians) but very clear and significant tilt variations on the radial component. On the basis of the theoreti- cal equations, these variation allow us to fix constraints on the SE conduit geometry (diameter) and the characteristics of the surrounding medium (rigidity coefficient).

  14. Evidences of correlation between the DAN active mode measurements variability and local surface micro-morphology diversity along the rover Curiosity traverse in the Gale crater

    NASA Astrophysics Data System (ADS)

    Kuzmin, Ruslan

    The Dynamic Albedo of Neutrons (DAN) instrument has been operational second year since almost immediately after the landing of the Mars Science Laboratory (MSL) on August 6, 2012 at the bottom of Gale Crater. In the report we present the result of the DAN measurement analysis, accumulated during 297-398 sols along the MSL rover Curiosity traverse from Yellowknife Bay (YKB) up to Darwin outcrop area (DOA). Along the part of the rover traverse the DAN instrument conducted 140 local active mode measurements of the thermal and epithermal neutrons counts in the top ~60 cm of the Martian subsurface with horizontal sensing “footprint” of about 3 m. As it well seen based on Navcam and Mastcam images, the modern dominant micro-morphology of the rover traverse area is characteristic of surface shaped by strong aeolian deflation processes. It was found that the thermal and epithermal neutron counts measured along the rover traverse show distinct variability from one rover location to another. At that, a water equivalent of H (WEH) distribution in 60-cm subsurface layer along the rover traverse are fit by a two-layers model, where the top layer (with varied thickness) has less WEH (“dry”) than the bottom layer (“wet”). It is notably that two-layer model of the water distribution in the subsurface layer corresponds well to both outcrops spots and deflated surfaces with variable top layer thickness, that is composed of finely granulated and coarse, rocky soil. This suggests that the boundary between the top and bottom layer may not represent a lithological difference but rather it is related with a level of surface regolith desiccation at the modern climatic conditions in the Gale crater area. In places where the surface regolith has been exposed for a longer period of time, the contrast in WEH between the top and bottom layers is essentially lower than in the cases of more recent surface regolith exposure by an aeolian erosion.

  15. Geology of McLaughlin Crater, Mars: A Unique Lacustrine Setting with Implications for Astrobiology

    NASA Technical Reports Server (NTRS)

    Michalski, J. R.; Niles, P. B.; Rogers, A. D.; Johnson, S. S.; Ashley, J. W.; Golombek, M. P.

    2016-01-01

    McLaughlin crater is a 92-kmdiameter Martian impact crater that contained an ancient carbonate- and clay mineral-bearing lake in the Late Noachian. Detailed analysis of the geology within this crater reveals a complex history with important implications for astrobiology [1]. The basin contains evidence for, among other deposits, hydrothermally altered rocks, delta deposits, deep water (>400 m) sediments, and potentially turbidites. The geology of this basin stands in stark contrast to that of some ancient basins that contain evidence for transient aqueous processes and airfall sediments (e.g. Gale Crater [2-3]).

  16. Bycatch, bait, anglers, and roads: quantifying vector activity and propagule introduction risk across lake ecosystems.

    PubMed

    Drake, D Andrew R; Mandrak, Nicholas E

    2014-06-01

    Long implicated in the invasion process, live-bait anglers are highly mobile species vectors with frequent overland transport of fishes. To test hypotheses about the role of anglers in propagule transport, we developed a social-ecological model quantifying the opportunity for species transport beyond the invaded range resulting from bycatch during commercial bait operations, incidental transport, and release to lake ecosystems by anglers. We combined a gravity model with a stochastic, agent-based simulation, representing a 1-yr iteration of live-bait angling and the dynamics of propagule transport at fine spatiotemporal scales (i.e., probability of introducing n propagules per lake per year). A baseline scenario involving round goby (Neogobius melanostomus) indicated that most angling trips were benign; irrespective of lake visitation, anglers failed to purchase and transport propagules (benign trips, median probability P = 0.99912). However, given the large number of probability trials (4.2 million live-bait angling events per year), even the rarest sequence of events (uptake, movement, and deposition of propagules) is anticipated to occur. Risky trips (modal P = 0.00088 trips per year; approximately 1 in 1136) were sufficient to introduce a substantial number of propagules (modal values, Poisson model = 3715 propagules among 1288 lakes per year; zero-inflated negative binomial model = 6722 propagules among 1292 lakes per year). Two patterns of lake-specific introduction risk emerged. Large lakes supporting substantial angling activity experienced propagule pressure likely to surpass demographic barriers to establishment (top 2.5% of lakes with modal outcomes of five to 76 propagules per year; 303 high-risk lakes with three or more propagules, per year). Small or remote lakes were less likely to receive propagules; however, most risk distributions were leptokurtic with a long right tail, indicating the rare occurrence of high propagule loads to most waterbodies

  17. Impact Cratering Calculations

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.

    2002-01-01

    Many Martian craters are surrounded by ejecta blankets which appear to have been fluidized forming lobate and layered deposits terminated by one or more continuous distal scarps, or ramparts. One of the first hypotheses for the formation of so-called rampart ejecta features was shock-melting of subsurface ice, entrainment of liquid water into the ejecta blanket, and subsequent fluidized flow. Our work quantifies this concept. Rampart ejecta found on all but the youngest volcanic and polar regions, and the different rampart ejecta morphologies are correlated with crater size and terrain. In addition, the minimum diameter of craters with rampart features decreases with increasing latitude indicating that ice laden crust resides closer to the surface as one goes poleward on Mars. Our second goal in was to determine what strength model(s) reproduce the faults and complex features found in large scale gravity driven craters. Collapse features found in large scale craters require that the rock strength weaken as a result of the shock processing of rock and the later cratering shear flows. In addition to the presence of molten silicate in the intensely shocked region, the presence of water, either ambient, or the result of shock melting of ice weakens rock. There are several other mechanisms for the reduction of strength in geologic materials including dynamic tensile and shear induced fracturing. Fracturing is a mechanism for large reductions in strength. We found that by incorporating damage into the models that we could in a single integrated impact calculation, starting in the atmosphere produce final crater profiles having the major features found in the field measurements (central uplifts, inner ring, terracing and faulting). This was accomplished with undamaged surface strengths (0.1 GPa) and in depth strengths (1.0 GPa).

  18. Some implications of large impact craters and basins on Venus for terrestrial ringed craters and planetary evolution

    NASA Technical Reports Server (NTRS)

    Mckinnon, W. B.; Alexopoulos, J. S.

    1994-01-01

    Approximately 950 impact craters have been identified on the surface of Venus, mainly in Magellan radar images. From a combination of Earth-based Arecibo, Venera 15/1, and Magellan radar images, we have interpreted 72 as unequivocal peak-ring craters and four as multiringed basins. The morphological and structural preservation of these craters is high owing to the low level of geologic activity on the venusian surface (which is in some ways similar to the terrestrial benthic environment). Thus these craters should prove crucial to understanding the mechanics of ringed crater formation. They are also the most direct analogs for craters formed on the Earth in Phanerozoic time, such as Chicxulub. We summarize our findings to date concerning these structures.

  19. Venus - Impact Crater 'Isabella

    NASA Technical Reports Server (NTRS)

    1992-01-01

    Crater Isabella, with a diameter of 175 kilometers (108 miles), seen in this Magellan radar image, is the second largest impact crater on Venus. The feature is named in honor of the 15th Century queen of Spain, Isabella of Castile. Located at 30 degrees south latitude, 204 degrees east longitude, the crater has two extensive flow-like structures extending to the south and to the southeast. The end of the southern flow partially surrounds a pre-existing 40 kilometer (25 mile) circular volcanic shield. The southeastern flow shows a complex pattern of channels and flow lobes, and is overlain at its southeastern tip by deposits from a later 20 kilometer (12 mile) diameter impact crater, Cohn (for Carola Cohn, Australian artist, 1892-1964). The extensive flows, unique to Venusian impact craters, are a continuing subject of study for a number of planetary scientists. It is thought that the flows may consist of 'impact melt,' rock melted by the intense heat released in the impact explosion. An alternate hypothesis invokes 'debris flows,' which may consist of clouds of hot gases and both melted and solid rock fragments that race across the landscape during the impact event. That type of emplacement process is similar to that which occurs in violent eruptions on Earth, such as the 1991 Mount Pinatubo eruption in the Philippines.

  20. The scaling of secondary craters

    NASA Technical Reports Server (NTRS)

    Croft, Steven K.

    1991-01-01

    Secondary craters are common features around fresh planetary-scale primary impact craters throughout most of the Solar System. They derive from the ejection phase of crater formation, thus secondary scaling relations provide constraints on parameters affecting ejection processes. Secondary crater fields typically begin at the edge of the continuous ejecta blankets (CEB) and extend out several crater radii. Secondaries tend to have rounded rims and bilateral symmetry about an axis through the primary crater's center. Prominent secondary chains can extend inward across the CEB close to the rim. A simple method for comparing secondary crater fields was employed: averaging the diameters and ranges from the center of the primary crater of the five largest craters in a secondary crater field. While not as much information is obtained about individual crater fields by this method as in more complete secondary field mapping, it facilitates rapid comparison of many secondary fields. Also, by quantifying a few specific aspects of the secondary crater field, this method can be used to construct scaling relations for secondary craters.

  1. Chilled margin fragmentation as a trigger for transition from Strombolian to phreatomagmatic explosive activity at Cova de Paul Crater, Santo Antao, Cape Verde Islands

    NASA Astrophysics Data System (ADS)

    Tarff, R. W.; Day, S. J.

    2013-07-01

    Sudden transitions from effusive or mildly explosive eruptions to violent phreatomagmatic explosive activity can occur at high-elevation vents on oceanic island volcanoes. Here, we describe near-vent deposits around the large Cova de Paul crater on Santo Antao, Cape Verde Islands, which provide insights into the transition from Strombolian magmatic to violently explosive phreatomagmatic activity during one such eruption. The Strombolian deposits change from welded spatter to bedded clinkery scoria to angular blocky scoria, and contain a distinct population of strongly banded, low-vesicularity angular sub-glassy clasts with strongly prolate vesicles. These sub-glassy clasts also form a discrete layer of larger blocks at the transition to the overlying phreatomagmatic deposits. They are compositionally identical to the Strombolian scoria and are interpreted to be fragments of flow-banded chilled margins from the walls of the eruptive conduit. The layer of large sub-glassy blocks records disintegration and expulsion of the chilled margins at the transition to phreatomagmatic activity. We interpret the sequence from spatter through clinkery scoria to blocky scoria as recording an increase in groundwater inflow into the conduit from pressurised aquifers, but at coolant input ratios below those required for explosions. The shattering of the chilled margins to produce the bed of large sub-glassy blocks appears to have allowed a much greater water flow into the conduit, leading to the phreatomagmatic explosive phase of the eruption.

  2. Small Impact Crater

    NASA Technical Reports Server (NTRS)

    2005-01-01

    22 June 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a small impact crater with a 'butterfly' ejecta pattern. The butterfly pattern results from an oblique impact. Not all oblique impacts result in an elliptical crater, but they can result in a non-radial pattern of ejecta distribution. The two-toned nature of the ejecta -- with dark material near the crater and brighter material further away -- might indicate the nature of subsurface materials. Below the surface, there may be a layer of lighter-toned material, underlain by a layer of darker material. The impact throws these materials out in a pattern that reflects the nature of the underlying layers.

    Location near: 3.7oN, 348.2oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Autumn

  3. 'Happy Face' Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-361, 15 May 2003

    Every day, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) wide angle instruments obtain a global view of the planet to help monitor weather and seasonal patterns of frost deposition and removal. The two pictures shown here are taken from the same daily global image mosaic (the only difference is that each was processed slightly differently). The pictures show Galle Crater, informally known as 'Happy Face,' as it appeared in early southern winter. The white-ish gray surfaces are coated with wintertime carbon dioxide frost. The pattern of frost distribution gives the appearance that 'Happy Face' has opened its mouth. Galle Crater is located on the east rim of Argyre at 51oS, 31oW. Sunlight illuminates the scene from the upper left. Galle Crater is 230 km (143 mi) across.

  4. Impact crater scaling laws

    NASA Technical Reports Server (NTRS)

    Holsapple, K. A.

    1987-01-01

    Impact craters are numerous on planetary bodies and furnish important information about the composition and past histories of those bodies. The interpretation of that information requires knowledge about the fundamental aspects of impact cratering mechanics. Since the typical conditions of impacts are at a size scale and velocity far in excess of experimental capabilities, direct simulations are precluded. Therefore, one must rely on extrapolation from experiments of relatively slow impacts of very small bodies, using physically based scaling laws, or must study the actual cases of interest using numerical code solutions of the fundamental physical laws that govern these processes. A progress report is presented on research on impact cratering scaling laws, on numerical studies that were designed to investigate those laws, and on various applications of the scaling laws developed by the author and his colleagues. These applications are briefly reviewed.

  5. 'Bonneville Crater' Panorama

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Click on the image for 'Bonneville Crater' Panorama (QTVR)

    This 360-degree view from a position beside the crater informally named 'Bonneville' was assembled from frames taken by the panoramic camera on NASA's Mars Exploration Rover Spirit. Half of this panorama was first released on March 15, 2004. The entire mosaic, recently completed, reveals not only the crater rim and interior, but Spirit's tracks and a glimpse at part of the rover. The images were acquired on sol 68, March 12, 2004, just one day after Spirit reached this location.

    The image is a false-color composite made from frames taken with the camera's L2 (750 nanometer), L5 (530 nanometer) and L6 (480 nanometer) filters.

  6. Craters! A Multi-Science Approach to Cratering and Impacts.

    ERIC Educational Resources Information Center

    Hartmann, William K.; Cain, Joe

    This book provides a complete Scope Sequence and Coordination teaching module. First, craters are introduced as a generally observable phenomena. Then, by making craters and by investigating the results, students gain close-up, hands-on experience with impact events and their products. Real crater examples from the Moon and elsewhere are included…

  7. Impact Materials of Takamatsu Crater in Japan

    NASA Astrophysics Data System (ADS)

    Miura, Y.; Okamoto, M.; Fukuchi, T.

    1995-09-01

    Shocked quartz materials have been found in Japanese K.T boundary (Hokkaido) and mountains of middle main-islands of Japan, though there are few direct evidence of "natural circular structure" on the surface in Japan. However circular structure has been recently found as a buried crater(up to 150m deep) [1] which is ca. 4km in diameter with -10 mgal of Bouguer gravity anomaly from surrounding Rhyoke granitic region of the southern part of Takamatsu City, Kagawa Prefecture, northeast Shikoku, Japan [1,2,3]. Two boring cores of 300m deep near small mountains inside the crater could not reach the bottom of the crater so far. From model calculation of the negative gravity anomaly, the Takamatsu crater shows deep basin structure up to 1.4km. If the Takamatsu crater is considered to be only impact crater, it is difficult to discuss only surface materials on the crater. But anomalous minerals are found only around small volcanic intrusions inside the crater, which the mixed minerals are clearly different with those of other volcanic intrusions of the Yashima and Goshikidai outside the crater [1,2,3]. The small volcanic intrusions are not origin of large Takamatsu crater, because the small volcanic intrusions are found on whole areas of Kagawa Prefecture. Major different activity of the small intrusions inside the crater is to bring the brecciated materials of the interior (esp. crater sediments). The xenolith materials around only volcanic intrusion of andesite are divided into the following four major mineral materials:(a) round pebble fragments from the Rhyoke granitic basement (Sampling No.15), (b) rock fragments from intruded biotite andesites (Nos. 2,15), (c) impact-induced fragments of shocked Quartz grains (Nos. 2,3,6,15), diaplectic feldspars (Nos. 2,3,6,15), silica glasses (Nos. 2,15) and small Fe-Ni metallic grains (No.15), and (d) small sedimentary fragments of halite and mordenite, as listed in Table 1. Table I, showing the characterization of surface samples

  8. Khensu Crater on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The dark-floored crater, Khensu, is the target of this image of Ganymede. The solid state imaging camera on NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. Khensu is located at 2 degrees latitude and 153 degrees longitude in a region of bright terrain known as Uruk Sulcus, and is about 13 kilometers (8 miles) in diameter. Like some other craters on Ganymede, it possesses an unusually dark floor and a bright ejecta blanket. The dark component may be residual material from the impactor that formed the crater. Another possibility is that the impactor may have punched through the bright surface to reveal a dark layer beneath.

    Another large crater named El is partly visible in the top-right corner of the image. This crater is 54 kilometers (34 miles) in diameter and has a small 'pit' in its center. Craters with such a 'central pit' are common across Ganymede and are especially intriguing since they may reveal secrets about the structure of the satellite's shallow subsurface.

    North is to the top-left of the picture and the sun illuminates the surface from nearly overhead. The image covers an area about 100 kilometers (62 miles) by 86 kilometers (54 miles) across at a resolution of 111 meters (370 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  9. Nergal Crater on Ganymede

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Two impact craters surrounded by an unusual ejecta blanket dominate this high resolution image of the surface of Jupiter's moon, Ganymede. NASA's Galileo spacecraft imaged this region as it passed Ganymede during its second orbit through the Jovian system. North is to the top of the picture and the sun illuminates the surface from the southeast. Nergal, the larger crater, is about eight kilometers (five miles) in diameter, while the smaller (unnamed) crater to its west is three kilometers (1.8 miles) across. The craters are situated in a region of bright grooved terrain named Byblus Sulcus, located in the northern part of Marius Regio at 39 degrees latitude and 201 degrees longitude. The distinctive ejecta blanket that surrounds them is darker nearer the craters and brighter further away. The inner region of the ejecta is characterized by a lobate appearance indicative of the flow of a liquid (or slushy) substance over the surface. The flow was probably icy surface material melted by the energy released during the impact that formed the crater.

    The picture covers an area about 48 kilometers (30 miles) by 34 kilometers (21 miles) across at a resolution of 86 meters (287 feet) per picture element. The image was taken on September 6, 1996 by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov.

  10. Constraining the activity of waves on Titan's polar lakes and seas

    NASA Astrophysics Data System (ADS)

    Soderblom, Jason M.; Barnes, Jason W.; Brown, Robert H.; Soderblom, Laurence A.; Sotin, Christophe; Clark, Roger N.; Le Mouélic, Stéphane; Rodriguez, Sebastien; Baines, Kevin H.; Buratti, Bonnie J.; Nicholson, Philip D.

    2015-04-01

    Saturn's moon Titan has an active hydrological cycle in which the primary working fluid, methane, is thought to transport between poles on seasonal timescales, driving much of the observed meteorology. Surface winds play a critical role in determining the evaporation rates of methane from Titan's polar lakes and seas. Observational constraints on these winds, however, are limited. Aeolian landforms, in particular sand dunes, characterize Titan's mid latitudes, providing evidence that winds at these latitudes have, at least in the geologically recent past, exceeded the threshold for saltation (which recent work has shown might be higher than previously predicted). The shoreline morphology of Titan's lone large southern lake, Ontario Lacus, has been interpreted as evidence for wave erosion. Evidence for wave activity on Titan's lakes and seas, however, has been notably absent in Cassini observations. Explanations that have been forwarded to explain the lack of waves include the possibility that the liquids that comprise Titan's lakes and seas are highly viscous or that seasonal winds have not exceeded the threshold for capillary wave formation (Hayes et al., 2012, Icarus 225). Only recently have Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations provided the first evidence of wave activity on Titan, in the north as Titan progresses towards northern summer (Barnes et al., 2014, Planetary Science 3). Herein, we use Cassini VIMS observations of the specular reflection of sunlight from Titan's lakes to infer the presence or absence of waves on Titan. We investigate observations acquired between 2012 and 2014. We find evidence for the presence of waves on Kraken Mare during a number of flybys, while specular reflections from the smaller Jingpo Lacus are more consistent with a smooth lake surface.

  11. An analogue experimental model of depth fluctuations in lava lakes

    NASA Astrophysics Data System (ADS)

    Witham, Fred; Woods, Andrew W.; Gladstone, Charlotte

    2006-07-01

    Lava lakes, consisting of molten degassing lava in summit craters of active basaltic volcanoes, sometimes exhibit complex cycles of filling and emptying on time-scales of hours to weeks such as recorded at Pu’u’O’o in Hawaii and Oldoinyo Lengai in Tanzania. Here we report on a new series of analogue laboratory experiments of two-phase flow in a reservoir-conduit-lava lake system which spontaneously generates oscillations in the depth of liquid within the lake. During the recharge phase, gas supplied from a subsurface reservoir of degassing magma drives liquid magma up the conduit, causing the lake to fill. As the magmastatic pressure in the lake increases, the upward supply of magma, driven by the gas bubbles, falls. Eventually the upflow becomes unstable, and liquid drains downwards from the lake, driven by the magmastatic pressure of the overlying lake, suppressing the ascent of any more bubbles from the chamber. At a later stage, once the lake has drained sufficiently, the descent speed of liquid through the conduit decreases below the ascent speed of the bubbles, and the recharge cycle resumes. Application of a quantitative model of the experiments to the natural system is broadly consistent with field data.

  12. Mass flux measurements at active lava lakes: Implications for magma recycling

    NASA Astrophysics Data System (ADS)

    Harris, Andrew J. L.; Flynn, Luke P.; Rothery, David A.; Oppenheimer, Clive; Sherman, Sarah B.

    1999-04-01

    Remotely sensed and field data can be used to estimate heat and mass fluxes at active lava lakes. Here we use a three thermal component pixel model with three bands of Landsat thematic mapper (TM) data to constrain the thermal structure of, and flux from, active lava lakes. Our approach considers that a subpixel lake is surrounded by ground at ambient temperatures and that the surface of the lake is composed of crusted and/or molten material. We then use TM band 6 (10.42-12.42 μm) with bands 3 (0.63-0.69 μm) or 4 (0.76-0.90 μm) and 5 (1.55-1.75 μm) or 7 (2.08-2.35 μm), along with field data (e.g., lava lake area), to place limits on the size and temperature of each thermal component. Previous attempts to achieve this have used two bands of TM data with a two-component thermal model. Using our model results with further field data (e.g., petrological data) for lava lakes at Erebus, Erta 'Ale, and Pu'u 'O'o, we calculate combined radiative and convective fluxes of 11-20, 14-27 and 368-373 MW, respectively. These yield mass fluxes, of 30-76, 44-104 and 1553-2079 kg s-1, respectively. We also identify a hot volcanic feature at Nyiragongo during 1987 from which a combined radiative and convective flux of 0.2-0.6 MW implies a mass flux of 1-2 kg s-1. We use our mass flux estimates to constrain circulation rates in each reservoir-conduit-lake system and consider four models whereby circulation results in intrusion within or beneath the volcano (leading to endogenous or cryptic growth) and/or magma mixing in the reservoir (leading to recycling). We suggest that the presence of lava lakes does not necessarily imply endogenous or cryptic growth: lava lakes could be symptomatic of magma recycling in supraliquidus reservoirs.

  13. Planetary cratering mechanics

    NASA Technical Reports Server (NTRS)

    Okeefe, John D.; Ahrens, Thomas J.

    1992-01-01

    To obtain a quantitative understanding of the cratering process over a broad range of conditions, we have numerically computed the evolution of impact induced flow fields and calculated the time histories of the major measures of crater geometry (e.g., depth diameter, lip height ...) for variations in planetary gravity (0 to 10 exp 9 cm/sq seconds), material strength (0 to 140 kbar), thermodynamic properties, and impactor radius (0.05 to 5000 km). These results were fit into the framework of the scaling relations of Holsapple and Schmidt (1987). We describe the impact process in terms of four regimes: (1) penetration; (2) inertial; (3) terminal; and (4) relaxation.

  14. Crater and Wind Streak

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-461, 23 August 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater with a bright wind streak in southern Acidalia Planitia. The streak is mostly likely a very thin coating of dust. The orientation of the streak indicates that the winds responsible for its formation and maintenance came from the northeast (upper right) and blew toward the lower left (southwest). The crater is located near 24.8oN, 39.1oW. The image covers an area 3 km (1.9 mi) wide. Sunlight illuminates the scene from the lower left.

  15. Layered Crater Walls

    NASA Technical Reports Server (NTRS)

    2006-01-01

    16 September 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows an impact crater that is approximately 3.5 kilometers (2.2 miles) in diameter. It is located to the northeast of Olympus Mons, in the Tharsis Region. Layered rock units are visible on the inside of the raised crater rim.

    Location near: 70.7oN, 271.0oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Spring

  16. 3D structure of the Gusev Crater region

    NASA Astrophysics Data System (ADS)

    Parker, Mirjam van Kan; Zegers, Tanja; Kneissl, Thomas; Ivanov, Boris; Foing, Bernard; Neukum, Gerhard

    2010-06-01

    Gusev Crater lies within the Aeolis Quadrangle of Mars at the boundary between the northern lowlands and southern highlands. The ancient valley Ma'adim Vallis dissects the highlands south of Gusev Crater and is thought to have fed the crater with sediments. High Resolution Stereo Camera data and Digital Elevation Models were used to construct a geologic-geomorphic map (173.5-178.5° E, 10-18° S) and cross-sections, complemented by data from Mars Orbiter Camera, Mars Orbiter Laser Altimeter and Thermal Emission Imaging System. Three geologic domains are recognised: the highlands in the south, Gusev Crater and lowlands in the north. Twelve units are mapped, with thicknesses ranging from hundred meters to several kilometres. Thicknesses of units, and their bedding attitude, are estimated combining the geologic map and topographic information. Relative ages are determined from crater counts, ranging from Early Noachian for highland units to Middle Amazonian for units in Gusev Crater and in lowlands. Episodes of intense geologic activity (deposition, volcanism, deformation) occur at around 4.0 Ga, 3.7 Ga, and 3.5 Ga. Comparing the geometry of the Gusev Crater with similar sized, filled and un-filled, Martian craters, suggests that the Columbia Hills are relics of the original central peak of Gusev Crater.

  17. Surface age of venus: use of the terrestrial cratering record

    SciTech Connect

    Schaber, G.G.; Shoemaker, E.M.; Kozak, R.C.

    1987-10-01

    The average crater age of Venus' northern hemisphere may be less than 250 m.y. assuming equivalence between the recent terrestrial cratering rate and that on Venus for craters greater than or equal to 20 km in diameter. For craters larger than this threshold size, below which crater production is significantly affected by the Venusian atmosphere, there are fairly strong observational grounds for concluding that such an equivalence in cratering rates on Venus and Earth may exist. However, given the uncertainties in the role of both active and inactive comet nuclei in the cratering history of Earth, we conclude that the age of the observed surface in the northern hemisphere of Venus could be as great as the 450-m.y. mean age of the Earth's crust. The observed surface of Venus might be even older, but no evidence from the crater observations supports an age as great as 1 b.y. If the age of the observed Venusian surface were 1 b.y., it probably should bear the impact scars of a half dozen or more large comet nuclei that penetrated the atmosphere and formed craters well over 100 km in diameter. Venera 15/16 mapped only about 25% of Venus; the remaining 75% may tell us a completely different story.

  18. OBJECTIVE ANALYSIS OF SPERM MOTILITY IN THE LAKE STURGEON, ACIPENSER FULVESCENS: ACTIVATION AND INHIBITION CONDITIONS

    EPA Science Inventory

    An objective analysis of the duration of motility of sperm from the lake sturgeon, Acipenser fulvescens, has been performed using computer-assisted sperm motion analysis at 200 frames/s. Motility was measured in both 1993 and 1994. The percentage of activated motile sperm and the...

  19. Quantitation of microorganic compounds in waters of the Great Lakes by adsorption on activated carbon

    USGS Publications Warehouse

    Daniels, Stacy L.; Kempe, Lloyd L.; Graham, E. S.; Beeton, Alfred M.

    1963-01-01

    Microorganic compounds in waters of Lakes Michigan and Huron have been sampled by adsorption on activated carbon in filters installed aboard the M/V Cisco and at the Hammond Bay Laboratory of the U.S. Bureau of Commercial Fisheries. The organic compounds were eluted from the carbon according to techniques developed at the U.S. Public Health Service. On the assumption that chloroform eluates represent less polar compounds from industrial sources and alcohol eluates the more polar varieties of natural origin, plots of chloroform eluates against alcohol eluates appear to be useful in judging water qualities. Based upon these criteria, the data in this paper indicate that both the waters of northern Lake Michigan and of Lake Huron, in the vicinity of Hammond Bay, Michigan, are relatively free from pollution. The limnetic waters of Lake Michigan showed a particularly high ratio of alcohol to chloroform eluates. Data for monthly samples indicated that this ratio fluctuated seasonally. The periodicity of the fluctuations was similar to those of lake levels and water temperatures.

  20. Identifying non-point sources of endocrine active compounds and their biological impacts in freshwater lakes.

    PubMed

    Baker, Beth H; Martinovic-Weigelt, Dalma; Ferrey, Mark; Barber, Larry B; Writer, Jeffery H; Rosenberry, Donald O; Kiesling, Richard L; Lundy, James R; Schoenfuss, Heiko L

    2014-10-01

    Contaminants of emerging concern, particularly endocrine active compounds (EACs), have been identified as a threat to aquatic wildlife. However, little is known about the impact of EACs on lakes through groundwater from onsite wastewater treatment systems (OWTS). This study aims to identify specific contributions of OWTS to Sullivan Lake, Minnesota, USA. Lake hydrology, water chemistry, caged bluegill sunfish (Lepomis macrochirus), and larval fathead minnow (Pimephales promelas) exposures were used to assess whether EACs entered the lake through OWTS inflow and the resultant biological impact on fish. Study areas included two OWTS-influenced near-shore sites with native bluegill spawning habitats and two in-lake control sites without nearby EAC sources. Caged bluegill sunfish were analyzed for plasma vitellogenin concentrations, organosomatic indices, and histological pathologies. Surface and porewater was collected from each site and analyzed for EACs. Porewater was also collected for laboratory exposure of larval fathead minnow, before analysis of predator escape performance and gene expression profiles. Chemical analysis showed EACs present at low concentrations at each study site, whereas discrete variations were reported between sites and between summer and fall samplings. Body condition index and liver vacuolization of sunfish were found to differ among study sites as did gene expression in exposed larval fathead minnows. Interestingly, biological exposure data and water chemistry did not match. Therefore, although results highlight the potential impacts of seepage from OWTS, further investigation of mixture effects and life history factor as well as chemical fate is warranted. PMID:24974177

  1. Tritium concentrations in the active Pu'u O'o crater, Kilauea volcano, Hawaii: implications for cold fusion in the Earth's interior

    USGS Publications Warehouse

    Quick, J.E.; Hinkley, T.K.; Reimer, G.M.; Hedge, C.E.

    1991-01-01

    The assertion that deuterium-deuterium fusion may occur at low temperature suggests a potential new source of geothermal heat. If a cold-fusion-like process occurs within the Earth, then a test for its existence would be a search for anomalous tritium in volcanic emissions. The Pu'u O'o crater is the first point at which large amounts of water are degassed from the magma that feeds the Kilauea system. The magma is probably not contaminated by meteoric-source ground water prior to degassing at Pu'u O'o, although mixing of meteoric and magmatic H2O occurs within the crater. Tritium contents of samples from within the crater are lower than in samples taken simultaneously from the nearby upwind crater rim. These results provide no evidence in support of a cold-fusion-like process in the Earth's interior. ?? 1991.

  2. An understudied crater in Nevada

    NASA Astrophysics Data System (ADS)

    Jamieson, Harry D.

    1992-09-01

    A little-known possible meteorite crater discovered in the early 1920's in Nye County, Nevada, by Ralph Irwing is described. The crater called the Irwing Crater was visited by the author on July 11, 1992. Photographs of the feature are presented.

  3. Secrets of the Wabar craters

    USGS Publications Warehouse

    Wynn, Jeffrey C.; Shoemaker, Eugene M.

    1997-01-01

    Focuses on the existence of craters in the Empty Quarter of Saudi Arabia created by the impact of meteors in early times. Mars Pathfinder and Mars Global Surveyor's encounter with impact craters; Elimination of craters in the Earth's surface by the action of natural elements; Impact sites' demand for careful scientific inspections; Location of the impact sites.

  4. Rim of Henry Crater

    NASA Technical Reports Server (NTRS)

    2002-01-01

    (Released 02 April 2002) This portion of the rim of Henry Crater has numerous dark streaks located on the slopes of the inner crater wall. These dark slope streaks have been suggested to have formed when the relatively bright dust that mantles the slopes slides downhill, either exposing a dust-free darker surface or creating a darker surface by increasing its roughness. The topography in this region appears muted, indicating the presence of regional dust mantling. The materials on floor of the crater (middle to lower left) are layered, with differing degrees of hardness and resistance to erosion producing cliffs (resistant layers) and ledges (easily eroded layers). These layered materials may have been originally deposited in water, although deposition by other means, such as windblown dust and sand, is also possible. Henry Crater, named after a 19th Century French astronomer, is 170 km in diameter and is located at 10.9o N, 336.7o W (23.3o E) in a region called Arabia Terra.

  5. Reading 'Endurance Crater'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site] Figure 1

    This image shows the area inside 'Endurance Crater' that the Mars Exploration Rover Opportunity has been examining. The rover is investigating the distinct layers of rock that make up this region. Each layer is defined by subtle color and texture variations and represents a separate chapter in Mars' history. The deeper the layer, the further back in time the rocks were formed. Scientists are 'reading' this history book by systematically studying each layer with the rover's scientific instruments. So far, data from the rover indicate that the top layers are sulfate-rich, like the rocks observed in 'Eagle Crater.' This implies that water processes were involved in forming the materials that make up these rocks.

    In figure 1, the layer labeled 'A' in this picture contains broken-up rocks that most closely resemble those of 'Eagle Crater.' Layers 'B,C and D' appear less broken up and more finely laminated. Layer 'E,' on the other hand, looks more like 'A.' At present, the rover is examining layer 'D.'

    So far, data from the rover indicates that the first four layers consist of sulfate-rich, jarosite-containing rocks like those observed in Eagle Crater. This implies that water processes were involved in forming the materials that make up these rocks, though the materials themselves may have been laid down by wind.

    This image was taken by Opportunity's navigation camera on sol 134 (June 9, 2004).

  6. A Periglacial Analog for Landforms in Gale Crater, Mars

    NASA Technical Reports Server (NTRS)

    Oehler, Dorothy Z.

    2013-01-01

    Several features in a high thermal inertia (TI) unit at Gale crater can be interpreted within a periglacial framework. These features include polygonally fractured terrain (cf. ice-wedge polygons), circumferential patterns of polygonal fractures (cf. relict pingos with ice-wedge polygons on their surfaces), irregularly-shaped and clustered depressions (cf. remnants of collapsed pingos and ephemeral lakes), and a general hummocky topography (cf. thermokarst). This interpretation would imply a major history of water and ice in Gale crater, involving permafrost, freeze-thaw cycles, and perhaps ponded surface water.

  7. Sediment History Preserved in Gale Crater Central Mound

    NASA Technical Reports Server (NTRS)

    2000-01-01

    [figure removed for brevity, see original site]

    While many of the layered outcrops in craters and chasms on Mars are seen as stair-stepped series of cliffs and benches composed of similar materials with similar thicknesses, other layer outcrops are expressed on relatively smooth, rounded slopes as alternating light and dark bands. The best example of this variety of layered sedimentary material is found in southern Holden Crater. Holden is located at 26.5oS, 33.9oW, and has a diameter of 141 km (88 mi). The context picture above, shows that a valley, Uzboi Vallis, enters the crater on its southwestern side. Not too far from where Uzboi Vallis meets Holden Crater, rounded slopes and buttes consisting of alternating light and dark bands are seen. The origin of these layers is not known, but like those found in other craters on Mars, they might have resulted from deposition of sediment in a lake that would have occupied Holden Crater. Alternatively, these are materials deposited by falling out of the air, the same way that volcanic ash is deposited on Earth. The Viking mosaic (above) images are illuminated by sunlight from the upper right. The MOC image (top left) is illuminated from the upper left. North is up.

  8. Impact Cratering Calculations

    NASA Technical Reports Server (NTRS)

    Ahrens, Thomas J.

    1997-01-01

    Understanding the physical processes of impact cratering on planetary surfaces and atmospheres as well as collisions of finite-size self-gravitating objects is vitally important to planetary science. The observation has often been made that craters are the most ubiquitous landform on the solid planets and the satellites. The density of craters is used to date surfaces on planets and satellites. For large ringed basin craters (e.g. Chicxulub), the issue of identification of exactly what 'diameter' transient crater is associated with this structure is exemplified by the arguments of Sharpton et al. (1993) versus those of Hildebrand et al. (1995). The size of a transient crater, such as the K/T extinction crater at Yucatan, Mexico, which is thought to be the source of SO,-induced sulfuric acid aerosol that globally acidified surface waters as the result of massive vaporization of CASO, in the target rock, is addressed by our present project. The impact process excavates samples of planetary interiors. The degree to which this occurs (e.g. how deeply does excavation occur for a given crater diameter) has been of interest, both with regard to exposing mantle rocks in crater floors, as well as launching samples into space which become part of the terrestrial meteorite collection (e.g. lunar meteorites, SNC's from Mars). Only in the case of the Earth can we test calculations in the laboratory and field. Previous calculations predict, independent of diameter, that the depth of excavation, normalized by crater diameter, is d(sub ex)/D = 0.085 (O'Keefe and Ahrens, 1993). For Comet Shoemaker-Levy 9 (SL9) fragments impacting Jupiter, predicted excavation depths of different gas-rich layers in the atmosphere, were much larger. The trajectory and fate of highly shocked material from a large impact on the Earth, such as the K/T bolide is of interest. Melosh et al. (1990) proposed that the condensed material from the impact upon reentering the Earth's atmosphere induced. radiative

  9. Europa's Pwyll Crater

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This view of the Pwyll impact crater on Jupiter's moon Europa taken by NASA's Galileo spacecraft shows the interior structure and surrounding ejecta deposits. Pwyll's location is shown in the background global view taken by Galileo's camera on December 16, 1997. Bright rays seen radiating from Pwyll in the global image indicate that this crater is geologically young. The rim of Pwyll is about 26 kilometers (16 miles) in diameter, and a halo of dark material excavated from below the surface extends a few kilometers beyond the rim. Beyond this dark halo, the surface is bright and numerous secondary craters can be seen. The closeup view of Pwyll, which combines imaging data gathered during the December flyby and the flyby of February 20, 1997, indicates that unlike most fresh impact craters, which have much deeper floors, Pwyll's crater floor is at approximately the same level as the surrounding background terrain.

    North is to the top of the picture and the sun illuminates the surface from the northeast. This closeup image, centered at approximately 26 degrees south latitude and 271 degrees west longitude, covers an area approximately 125 by 75 kilometers (75 by 45 miles). The finest details that can be discerned in this picture are about 250 meters (800 feet) across. This image was taken on at a range of 12,400 kilometers (7,400 miles), with the green filter of Galileo's solid state imaging system.

    The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/ galileo.

  10. Microbial processes and factors controlling their activities in alkaline lakes of the Mongolian plateau

    NASA Astrophysics Data System (ADS)

    Namsaraev, Zorigto B.; Zaitseva, Svetlana V.; Gorlenko, Vladimir M.; Kozyreva, Ludmila P.; Namsaraev, Bair B.

    2015-11-01

    A striking feature of the Mongolian plateau is the wide range of air temperatures during a year, -30 to 30°C. High summer temperatures, atmospheric weathering and the arid climate lead to formation of numerous alkaline soda lakes that are covered by ice during 6-7 months per year. During the study period, the lakes had pH values between 8.1 to 10.4 and salinity between 1.8 and 360 g/L. According to chemical composition, the lakes belong to sodium carbonate, sodium chloride-carbonate and sodium sulfate-carbonate types. This paper presents the data on the water chemical composition, results of the determination of the rates of microbial processes in microbial mats and sediments in the lakes studied, and the results of a Principal Component Analysis of environmental variables and microbial activity data. Temperature was the most important factor that influenced both chemical composition and microbial activity. pH and salinity are also important factors for the microbial processes. Dark CO2 fixation is impacted mostly by salinity and the chemical composition of the lake water. Total photosynthesis and sulfate-reduction are impacted mostly by pH. Photosynthesis is the dominant process of primary production, but the highest rate (386 mg C/(L•d)) determined in the lakes studied were 2-3 times lower than in microbial mats of lakes located in tropical zones. This can be explained by the relatively short warm period that lasts only 3-4 months per year. The highest measured rate of dark CO2 assimilation (59.8 mg C/(L•d)) was much lower than photosynthesis. The highest rate of sulfate reduction was 60 mg S/(L•d), while that of methanogenesis was 75.6 μL CN4/(L•d) in the alkaline lakes of Mongolian plateau. The rate of organic matter consumption during sulfate reduction was 3-4 orders of magnitude higher than that associated with methanogenesis.

  11. Decreased glutathione S-transferase expression and activity and altered sex steroids in Lake Apopka brown bullheads (Ameriurus nebulosus)

    USGS Publications Warehouse

    Gallagher, E.P.; Gross, T.S.; Sheehy, K.M.

    2001-01-01

    A number of freshwater lakes and reclaimed agricultural sites in Central Florida have been the receiving waters for agrochemical and municipal runoff. One of these sites, Lake Apopka, is also a eutrophic system that has been the focus of several case studies reporting altered reproductive activity linked to bioaccumulation of persistent organochlorine chemicals in aquatic species. The present study was initiated to determine if brown bullheads (Ameriurus nebulosus) from the north marsh of Lake Apopka (Lake Apopka Marsh) exhibit an altered capacity to detoxify environmental chemicals through hepatic glutathione S-transferase (GST)-mediated conjugation as compared with bullheads from a nearby reference site (Lake Woodruff). We also compared plasma sex hormone concentrations (testosterone, 17-?? estradiol, and 11 keto-testosterone) in bullheads from the two sites. Female bullheads from Lake Apopka had 40% lower initial rate GST conjugative activity toward 1-chloro-2,4-dinitrobenzene (CDNB), 50% lower activity towards p-nitrobutyl chloride (NBC), 33% lower activity toward ethacrynic acid (ECA), and 43% lower activity toward ??5-androstene-3,17-dione (??5-ADI), as compared with female bullheads from Lake Woodruff. Enzyme kinetic analyses demonstrated that female bullheads from Lake Apopka had lower GST-catalyzed CDNB clearance than did female Lake Woodruff bullheads. Western blotting studies of bullhead liver cytosolic proteins demonstrated that the reduced GST catalytic activities in female Lake Apopka bullheads were accompanied by lower expression of hepatic GST protein. No site differences were observed with respect to GST activities or GST protein expression in male bullheads. Female Lake Apopka bullheads also had elevated concentrations of plasma androgens (testosterone and 11-ketotestosterone) as compared with females from Lake Woodruff. In contrast, male Lake Apopka bullheads had elevated levels of plasma estrogen but similar levels of androgens as compared with

  12. Layered Outcrops in Gusev Crater

    NASA Technical Reports Server (NTRS)

    2004-01-01

    NASA's Mars Exploration Rover Spirit collected data on morphology, composition, and mineralogy of a rock nicknamed 'Tetl' using the microscopic imager, the alpha particle X-ray spectrometer, and the Moessbauer spectrometer before moving on. Scientists are discussing a suggestion that this rock outcrop and others on the 'West Spur' of the 'Columbia Hills' in Gusev Crater on Mars may contain evidence of graded bedding, in which alternate layers of sediment are either coarser or finer depending on the turbulence of the processes that deposited them. Such layers could be deposited by water circulating in rivers or lakes, volcanic ash settling on the surface, wind carrying fine-grained sediments, or a combination of these processes. This view is a mosaic of images that Spirit took with its microscopic imager on the rover's 272nd and 273rd martian days, or sols (Oct. 7 and 8, 2004). It has been enhanced to bring out details in the shadows without washing out sunlit areas. The section of rock shown here is approximately 17 centimeters (6.7 inches) wide.

  13. 'Erebus Crater' on the Horizon

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This is a mosaic assembled from some of the images taken by the panoramic camera on NASA's Mars Exploration Rover Opportunity during the rover's 590th sol (Sept. 21, 2005). The view is toward the south and includes rock exposures north of 'Erebus Crater,' with the crater in the background. The rover will investigate the exposed rocks in the foreground and will take additional panoramic-camera images of Erebus Crater, which is about 300 meters (about 984 feet) across.

    Erebus Crater dwarfs the landing-site crater, 'Eagle Crater,' which measures about 22 meters (72 feet) in diameter. And, it is nearly twice the diameter of 'Endurance Crater,' which, at 130 meters (430 feet) wide, has been compared to a stadium.

    The camera's red filter was used for taking the images in this mosaic. It admits light with a wavelength of 750 nanometers.

  14. Exploring Martian Impact Craters: Why They are Important for the Search for Life

    NASA Technical Reports Server (NTRS)

    Schwenzer, S. P.; Abramov, O.; Allen, C. C.; Clifford, S.; Filiberto, J.; Kring, D. A.; Lasue, J.; McGovern, P. J.; Newsom, H. E.; Treiman, A. H.; Vaniman, D. T.; Wiens, R. C.; Wittmann, A.

    2010-01-01

    Fluvial features and evidence for aqueous alteration indicate that Mars was wet, at least partially and/or periodically, in the Noachian. Also, impact cratering appears to have been the dominant geological process [1] during that epoch. Thus, investigation of Noachian craters will further our understanding of this geologic process, its effects on the water-bearing Martian crust, and any life that may have been present at the time. Impact events disturbed and heated the water- and/or ice-bearing crust, likely initiated long-lived hydrothermal systems [2-4], and formed crater lakes [5], creating environments suitable for life [6]. Thus, Noachian impact craters are particularly important exploration targets because they provide a window into warm, water-rich environments of the past which were possibly conducive to life. In addition to the presence of lake deposits, assessment of the presence of hydrothermal deposits in the walls, floors and uplifts of craters is important in the search for life on Mars. Impact craters are also important for astrobiological exploration in other ways. For example, smaller craters can be used as natural excavation pits, and so can provide information and samples that would otherwise be inaccessible (e.g., [7]). In addition, larger (> 75 km) craters can excavate material from a potentially habitable region, even on present-day Mars, located beneath a >5-km deep cryosphere.

  15. Highly Active Microbial Communities in the Ice and Snow Cover of High Mountain Lakes

    PubMed Central

    Felip, M.; Sattler, B.; Psenner, R.; Catalan, J.

    1995-01-01

    An exploratory study carried out in Pyrenean and Alpine lakes shows that a rich, active microbial community lives in the slush layers of the winter cover of such lakes in spite of the low temperature and the seasonal occurrence of the habitat. Bacteria were very diverse in morphology, with filaments reaching up to 100 (mu)m long; flagellates, both autotrophic (chrysophytes, cryptophytes, dinoflagellates, and volvocales) and heterotrophic, and ciliates were abundant, reaching biovolume values up to 2.7 x 10(sup6) (mu)m(sup3) ml(sup-1). Species composition was very variable, with dominance depending on date and depth. Although many species were typical of lake plankton communities, some were restricted to the slush, for instance the predatory ciliates Dileptus sp. and Lacrymaria sp., and others were restricted to the surface pools, such as the snow algae Chlamydomonas nivalis. Microbial biomasses and usually bacterial and algal activities were greater in the slush layers than in the lake water. Photosynthesis rate in the upper cover layers reached values up to 0.5 (mu)g of C liter(sup-1) h(sup-1), and high bacterial activities up to 226 pmol of leucine incorporated liter(sup-1) h(sup-1) and 25 pmol of thymidine incorporated liter(sup-1) h(sup-1) were measured. For most species, lake water flooding the ice and snow cover could provide an inoculum. Differential growth depending on the environmental conditions (nutrients, organic matter, light) of a particular slush layer could provide dominance of different groups or species. However, there was no obvious colonizing mechanism for those species not appearing either in plankton or in communities on top of the snowpack. PMID:16535056

  16. Highly active microbial communities in the ice and snow cover of high mountain lakes.

    PubMed

    Felip, M; Sattler, B; Psenner, R; Catalan, J

    1995-06-01

    An exploratory study carried out in Pyrenean and Alpine lakes shows that a rich, active microbial community lives in the slush layers of the winter cover of such lakes in spite of the low temperature and the seasonal occurrence of the habitat. Bacteria were very diverse in morphology, with filaments reaching up to 100 (mu)m long; flagellates, both autotrophic (chrysophytes, cryptophytes, dinoflagellates, and volvocales) and heterotrophic, and ciliates were abundant, reaching biovolume values up to 2.7 x 10(sup6) (mu)m(sup3) ml(sup-1). Species composition was very variable, with dominance depending on date and depth. Although many species were typical of lake plankton communities, some were restricted to the slush, for instance the predatory ciliates Dileptus sp. and Lacrymaria sp., and others were restricted to the surface pools, such as the snow algae Chlamydomonas nivalis. Microbial biomasses and usually bacterial and algal activities were greater in the slush layers than in the lake water. Photosynthesis rate in the upper cover layers reached values up to 0.5 (mu)g of C liter(sup-1) h(sup-1), and high bacterial activities up to 226 pmol of leucine incorporated liter(sup-1) h(sup-1) and 25 pmol of thymidine incorporated liter(sup-1) h(sup-1) were measured. For most species, lake water flooding the ice and snow cover could provide an inoculum. Differential growth depending on the environmental conditions (nutrients, organic matter, light) of a particular slush layer could provide dominance of different groups or species. However, there was no obvious colonizing mechanism for those species not appearing either in plankton or in communities on top of the snowpack. PMID:16535056

  17. Enceladus' extreme heat flux as revealed by its relaxed craters

    NASA Astrophysics Data System (ADS)

    Bland, Michael T.; Singer, Kelsi N.; McKinnon, William B.; Schenk, Paul M.

    2012-09-01

    Enceladus' cratered terrains contain large numbers of unusually shallow craters consistent with deformation by viscous relaxation of water ice under conditions of elevated heat flow. Here we use high-resolution topography to measure the relaxation fraction of craters on Enceladus far from the active South Pole. We find that many craters are shallower than expected, with craters as small as 2 km in diameter having relaxation fractions in excess of 90%. These measurements are compared with numerical simulations of crater relaxation to constrain the minimum heat flux required to reproduce these observations. We find that Enceladus' nominal cold surface temperature (70 K) and low surface gravity strongly inhibit viscous relaxation. Under such conditions less than 3% relaxation occurs over 2 Ga even for relatively large craters (diameter 24 km) and high, constant heat fluxes (150 mW m-2). Greater viscous relaxation occurs if the effective temperature at the top of the lithosphere is greater than the surface temperature due to insulating regolith and/or plume material. Even for an effective temperature of 120 K, however, heat fluxes in excess of 150 mW m-2 are required to produce the degree of relaxation observed. Simulations of viscous relaxation of Enceladus' largest craters suggest that relaxation is best explained by a relatively short-lived period of intense heating that decayed quickly. We show that infilling of craters by plume material cannot explain the extremely shallow craters at equatorial and higher northern latitudes. Thus, like Enceladus' tectonic terrains, the cratered regions of Enceladus have experienced periods of extreme heat flux.

  18. Birth of a lava lake: Nyamulagira volcano 2011-2015

    NASA Astrophysics Data System (ADS)

    Coppola, D.; Campion, R.; Laiolo, M.; Cuoco, E.; Balagizi, C.; Ripepe, M.; Cigolini, C.; Tedesco, D.

    2016-03-01

    Since 1938, Nyamulagira volcano (Democratic Republic of Congo) has operated as a classic pressurized basaltic closed system, characterized by frequent dike-fed flank eruptions. However, on June 24, 2014, an active lava lake was observed in its summit, after a period of 76 years. The small lava lake is now exposed at the bottom of a pit-crater and is rising and growing. Based on satellite-derived infrared (IR) data, SO2 fluxes and periodic field surveys, we provide evidence that the development of the lava lake was gradual and occurred more than 2 years before it was first observed in the field. Notably, this process followed the voluminous 2011-2012 distal flank eruption and was coeval with weakening of the central rock column below the summit. Hence, the opening and development of the pit-crater favoured the continuous rise of fresh magma through the central conduit and promoted the gradual "re-birth" of the Nyamulagira lava lake. Budgeted volumes of magma erupted, and magma degassed at depth indicate that the formation of the lava lake is due to the draining and refilling of a shallow plumbing system (1-2 km depth), probably in response to the rift-parallel 2011-2012 distal eruption. We thus suggest that the transition from lateral to central activity did not result from a substantial change in the magma supply rate but, more likely, from the perturbation of the plumbing system (and related stress field) associated with the distal eruption. The processes observed at Nyamulagira are not unique and suggest that rift-fissure eruptions, in addition to triggering caldera collapses or lava lake drainages, may also induce a progressive resumption of central vent activity. Current activity at Nyamulagira represents a tangible and major hazard for the population living at the base of its southern flank.

  19. Central pit craters on Ganymede

    NASA Astrophysics Data System (ADS)

    Alzate, Nathalia; Barlow, Nadine G.

    2011-02-01

    Central pit craters are common on Mars, Ganymede and Callisto, and thus are generally believed to require target volatiles in their formation. The purpose of this study is to identify the environmental conditions under which central pit craters form on Ganymede. We have conducted a study of 471 central pit craters with diameters between 5 and 150 km on Ganymede and compared the results to 1604 central pit craters on Mars (diameter range 5-160 km). Both floor and summit pits occur on Mars whereas floor pits dominate on Ganymede. Central peak craters are found in similar locations and diameter ranges as central pit craters on Mars and overlap in location and at diameters <60 km on Ganymede. Central pit craters show no regional variations on either Ganymede or Mars and are not concentrated on specific geologic units. Central pit craters show a range of preservation states, indicating that conditions favoring central pit formation have existed since crater-retaining surfaces have existed on Ganymede and Mars. Central pit craters on Ganymede are generally about three times larger than those on Mars, probably due to gravity scaling although target characteristics and resolution also may play a role. Central pits tend to be larger relative to their parent crater on Ganymede than on Mars, probably because of Ganymede's purer ice crust. A transition to different characteristics occurs in Ganymede's icy crust at depths of 4-7 km based on the larger pit-to-crater-diameter relationship for craters in the 70-130-km-diameter range and lack of central peaks in craters larger than 60-km-diameter. We use our results to constrain the proposed formation models for central pits on these two bodies. Our results are most consistent with the melt-drainage model for central pit formation.

  20. Creation of High Resolution Terrain Models of Barringer Meteorite Crater (Meteor Crater) Using Photogrammetry and Terrestrial Laser Scanning Methods

    NASA Technical Repor