Relative importance of fluvial and glacial erosion in shaping the Chandra Valley, western Himalaya, India

Abstract HKT-ISTP 2013 B

Combined seismic and borehole investigation of the deep granite weathering structure—Santa Gracia Reserve case in Chile

Imaging the critical zone at depth, where intact bedrock transforms into regolith, is critical in understanding the interaction between geological and biological processes. We acquired a 500 m‐long near‐surface seismic profile to investigate the weathering structure in the Santa Gracia National Reserve, Chile, which is located in a granitic environment in an arid climate. Data processing comprised the combination of two seismic approaches: (1) body wave tomography and (2) multichannel analysis of surface wave (MASW) with Bayesian inversion. This allowed us to derive P‐wave and S‐wave velocity models down to 90 and 70 m depth, respectively. By calibrating the seismic results with those from an 87 m‐deep borehole that is crossed by the profile. We identified the boundaries of saprolite, weathered bedrock, and bedrock. These divisions are indicated in the seismic velocity variations and refer to weathering effects at depth. The thereby determined weathering front in the borehole location can be traced down to 30 m depth. The modelled lateral extent of the weathering front, however, cannot be described by an established weathering front model. The discrepancies suggest a more complex interaction between different aspects such as precipitation and topography in controlling the weathering front depth

Paleo-denudation rates suggest variations in runoff drove aggradation during last glacial cycle, Crete, Greece

Fluvial aggradation and incision are often linked to Quaternary climate cycles, but it usually remains unclear whether variations in runoff or sediment supply or both drive channel response to climate variability. Here we quantify sediment supply with paleo-denudation rates and provide geochronological constraints on aggradation and incision from the Sfakia and Elafonisi alluvial-fan sequences in Crete, Greece. We report seven optically stimulated luminescence (OSL)and ten radiocarbon ages, eight 10Be,and eight 36Cl denudation rates from modern channeland terrace sediments. For five samples, 10Be and 36Cl were measured on the same sample by measuring 10Be on chert and 36Cl on calcite. Results indicate relatively steady denudation rates throughout the past 80kyr, but the aggradation and incision history indicates a link with climate shifts. At the Elafonisi fan, we identify four periods of aggradation coinciding with Marine Isotope Stages (MIS) 2, 4, 5a/b, and likely 6, and three periods of incision coinciding with MIS 1, 3, and likely 5e. At the Sfakia fan, rapid aggradation occurred during MIS 2 and 4,followed by incision during MIS 1. Nearby climate and vegetation records show that MIS 2, 4, and 6 stadials were characterized by cold and dry climates with sparse vegetation, whereas forest cover and more humid conditions prevailed during MIS 1, 3, and 5. Our data thus suggest that past changes in climate had little effect on landscape-wide denudation rates but exerted a strong control on the aggradation-incision behaviour of alluvial channels on Crete. During glacial stages, we attribute aggradation to hillslope sediment release promoted by reduced vegetation cover and decreased runoff; conversely, incision occurred during relatively warm and wet stages due to increased runoff. In this landscape, past hydroclimate variations outcompeted changes in sediment supply as the primary driver of alluvial deposition and incision

Paleo-denudation rates suggest variations in runoff drove aggradation during last glacial cycle, Crete, Greece

Fluvial aggradation and incision are often linked to Quaternary climate cycles, but it usually remains unclear whether variations in runoff or sediment supply or both drive channel response to climate variability. Here we quantify sediment supply with paleo-denudation rates and provide geochronological constraints on aggradation and incision from the Sfakia and Elafonisi alluvial-fan sequences in Crete, Greece. We report seven optically stimulated luminescence and ten radiocarbon ages, eight 10Be and eight 36Cl denudation rates from modern channel and terrace sediments. For five samples, 10Be and 36Cl were measured on the same sample by measuring 10Be on chert and 36Cl on calcite. Results indicate relatively steady denudation rates throughout the past 80 kyr, but the aggradation and incision history indicates a link with climate shifts. At the Elafonisi fan, we identify four periods of aggradation coinciding with Marine Isotope Stages (MIS) 2, 4, 5a/b, and likely 6, and three periods of incision coinciding with MIS 1, 3, and likely 5e. At the Sfakia fan, rapid aggradation occurred during MIS 2 and 4, followed by incision during MIS 1. Nearby climate and vegetation records show that MIS 2, 4, and 6 stadials were characterized by cold and dry climates with sparse vegetation, whereas forest cover and more humid conditions prevailed during MIS 1, 3, and 5. Our data thus suggest that past changes in climate had little effect on landscape-wide denudation rates but exerted a strong control on the aggradation–incision behaviour of alluvial channels on Crete. During glacial stages, we attribute aggradation to hillslope sediment release promoted by reduced vegetation cover and decreased runoff; conversely, incision occurred during relatively warm and wet stages due to increased runoff. In this landscape, past hydroclimate variations outcompeted changes in sediment supply as the primary driver of alluvial deposition and incision

Including debris cover effects in a distributed model of glacier ablation

Distributed glacier melt models generally assume that the glacier surface consists of bare exposed ice and snow. In reality, many glaciers are wholly or partially covered in layers of debris that tend to suppress ablation rates. In this paper, an existing physically based point model for the ablation of debris-covered ice is incorporated in a distributed melt model and applied to Haut Glacier d’Arolla, Switzerland, which has three large patches of debris cover on its surface. The model is based on a 10 m resolution digital elevation model (DEM) of the area; each glacier pixel in the DEM is defined as either bare or debris-covered ice, and may be covered in snow that must be melted off before ice ablation is assumed to occur. Each debris-covered pixel is assigned a debris thickness value using probability distributions based on over 1000 manual thickness measurements. Locally observed meteorological data are used to run energy balance calculations in every pixel, using an approach suitable for snow, bare ice or debris-covered ice as appropriate. The use of the debris model significantly reduces the total ablation in the debris-covered areas, however the precise reduction is sensitive to the temperature extrapolation used in the model distribution because air near the debris surface tends to be slightly warmer than over bare ice. Overall results suggest that the debris patches, which cover 10% of the glacierized area, reduce total runoff from the glacierized part of the basin by up to 7%

Longitudinal peripheral blood transcriptional analysis of a patient with severe Ebola virus disease.

The 2013-2015 outbreak of Ebola virus disease in Guinea, Liberia, and Sierra Leone was unprecedented in the number of documented cases, but there have been few published reports on immune responses in clinical cases and their relationships with the course of illness and severity of Ebola virus disease. Symptoms of Ebola virus disease can include severe headache, myalgia, asthenia, fever, fatigue, diarrhea, vomiting, abdominal pain, and hemorrhage. Although experimental treatments are in development, there are no current U.S. Food and Drug Administration-approved vaccines or therapies. We report a detailed study of host gene expression as measured by microarray in daily peripheral blood samples collected from a patient with severe Ebola virus disease. This individual was provided with supportive care without experimental therapies at the National Institutes of Health Clinical Center from before onset of critical illness to recovery. Pearson analysis of daily gene expression signatures revealed marked gene expression changes in peripheral blood leukocytes that correlated with changes in serum and peripheral blood leukocytes, viral load, antibody responses, coagulopathy, multiple organ dysfunction, and then recovery. This study revealed marked shifts in immune and antiviral responses that preceded changes in medical condition, indicating that clearance of replicating Ebola virus from peripheral blood leukocytes is likely important for systemic viral clearance

Арап элифбесинде нешир этильген къырымтатар грамматикаларнынъ тенъештирме талили

Статья посвящена сопоставительному анализу имени существительного и глагола в арабографических грамматиках крымскотатарского языка.Стаття присвячена порівняльному аналізу іменника і дієслова в арабографічних граматиках кримськотатарської мови.The article annotation is devoted to the comparative analysis of the noun and the verb in arabographis grammars of the Crimean Tatar language

Impact of transient groundwater storage on the discharge of Himalayan rivers

International audienceIn the course of the transfer of precipitation into rivers, water is temporarily stored in reservoirs with different residence times such as soils, groundwater, snow and glaciers. In the central Himalaya, the water budget is thought to be primarily controlled by monsoon rainfall, snow and glacier melt, and secondarily by evapotranspiration. An additional contribution from deep groundwater has been deduced from the chemistry of Himalayan rivers, but its importance in the annual water budget remains to be evaluated. Here we analyse records of daily precipitation and discharge within twelve catchments in Nepal over about 30 years. We observe annual hysteresis loops--that is, a time lag between precipitation and discharge--in both glaciated and unglaciated catchments and independent of the geological setting. We infer that water is stored temporarily in a reservoir with characteristic response time of about 45 days, suggesting a diffusivity typical of fractured basement aquifers. We estimate this transient storage capacity at about 28km3 for the three main Nepal catchments; snow and glacier melt contribute around 14km3yr-1, about 10% of the annual river discharge. We conclude that groundwater storage in a fractured basement influences significantly the Himalayan river discharge cycle

Twenty-first century glacier slowdown driven by mass loss in High Mountain Asia

International audienc

A new Late Agenian (MN2a, Early Miocene) fossil assemblage from Wallenried (Molasse Basin, Canton Fribourg, Switzerland)

Excavations of two fossiliferous layers in the Wallenried sand- and marl pit produced a very diversified vertebrate fauna. New material allows the reassessment of the taxonomic position of the ruminant taxa Andegameryx andegaviensis and endemic Friburgomeryx wallenriedensis. An emended diagnosis for the second species is provided and additional material of large and small mammals, as well as ectothermic vertebrates, is described. The recorded Lagomorpha show interesting morphological deviations from other Central European material, and probably represent a unique transitional assemblage with a co-occurrence of Titanomys, Lagopsis and Prolagus. Rodentia and Eulipotyphla belong to typical and well-known species of the Agenian of the Swiss Molasse Basin. Abundant small mammal teeth have allowed us to pinpoint the biostratigraphic age of Wallenried to late MN2a. The biostratigraphic age conforms to data derived from the charophyte assemblages and confirms the oldest occurrence of venomous snake fangs. The palaeoenvironmental context is quite complex. Sedimentary structures and fauna (fishes, frogs, salamanders, ostracods) are characteristic for a humid, lacustrine environment within a flood plain system