A late Holocene Record of sediment dynamics obtained from Lake Altaussee (Salzkammergut, Austria). 

2021 ◽  
Author(s):  
Jasper Moernaut ◽  
Sebastian Wagner ◽  
Julia Rechenmacher ◽  
Markus Fiebig ◽  
Marcel Ortler ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Mass Movement ◽  
Sediment Dynamics ◽  
Coastal Sediments ◽  
Coarse Grained ◽  
Lake Basin ◽  
Stratigraphic Correlation ◽  
X Ray ◽  
The University ◽  
Subbottom Profiling

<p>Sedimentary records in inner-Alpine lakes typically show a rich history of changes in sediment dynamics and the occurrence of various geohazards. Lake Altaussee (712 m asl; 2.4 x 1.0 km; max. 72 m deep) is a dimictic, moderately-sized glacigenic lake located in the Northern Calcareous Alps. Currently, it has no major river inflow and most water input comes from several subaqueous springs, forming large and deep craters (max. 60 m diameter and 22 m deep) on the lake bottom. Since 2019, a wide suite of investigations (hydrogeology, microplastics, hydroacoustics, geomorphology, sedimentology) started under the framework of the Walter Munk Foundation for the Oceans (WMFO) and the University of Natural Resources and Life Sciences (BOKU) Vienna. In 2020, the University of Innsbruck (UIBK) became a project partner to undertake joint research on its sedimentary infill.</p><p>We present preliminary results from lacustrine morphological mapping of high-resolution multibeam bathymetry (Kongsberg EM2040), seismic-stratigraphic analysis of subbottom profiling data (Innomar SES-2000 and Kongsberg GEOPULSE), and sedimentological/geochemical analysis on 22 short cores (60-170 cm long). Stratigraphic correlation between the 22 cores is based on visual detection of marker layers in Multi-Sensor Core Logging (MSCL), X-Ray CT and X-ray fluorescence (XRF) core scanning data.</p><p>The sediment cores mainly exhibit slowly-accumulating organic-rich sediments, typical for lake systems that lack significant fluvial sediment input. One unit of finely-laminated clastic carbonate-rich sedimentation can be traced back to an episode in which a major creek −draining an area of active salt mining− was flowing into the western part of the lake. In medieval times, this creek was artificially diverted and depositional conditions in the lake returned to organic-rich sedimentation. </p><p>The hydroacoustic data show a scattered pattern of large-scale blocks up to 50-70 m diameter in the eastern half of the lake basin. This suggests the occurrence of one or more large gravitational mass movements, which potentially originated at the steep rock slopes at the northern and eastern end of the lake. A megaturbidite (>1-2 m thick) can be traced over the entire basin floor in both subbottom profiling data and sediment cores, and directly overlies the blocks in the deep basin. Isopach mapping of this megaturbidite hints at sediment transport from both the eastern and western slopes, which we interpret to have occurred as the results of a mass-movement induced impulse wave that eroded coastal sediments at the opposite side of the lake and transported these to the deeper basin. On the shallower western plateau, the presence of an outstanding coarse-grained stratigraphic unit with an erosive base further supports this hypothesis, as it is stratigraphically coeval to the megaturbidite. Biogenic gas accumulation at the base of the megaturbidite prevents further penetration on the subbottom profiles, but some acoustic windows visualize up to 15 m of infill.</p><p>Upcoming research involves the establishment of <sup>14</sup>C-based age-depth models, the acquisition of single-channel airgun seismics to visualize the entire infill of the lake through the gas blanket, and long piston coring to investigate the sediment dynamics and geohazards recorded in the Holocene sedimentary infill.</p>

scholarly journals A tsunamigenic delta collapse and its associated tsunami deposits in and around Lake Sils, Switzerland

2021 ◽  
Author(s):  
Valentin Nigg ◽  
Stephan Wohlwend ◽  
Michael Hilbe ◽  
Benjamin Bellwald ◽  
Stefano C. Fabbri ◽  
...  
Keyword(s):  
Coastal Plain ◽  
Sediment Cores ◽  
Mass Movement ◽  
Coarse Grained ◽  
Sediment Provenance ◽  
Lake Basin ◽  
Tsunami Deposits ◽  
Wave Heights ◽  
Event Deposit ◽  
Common Era

AbstractLarge lacustrine mass movements and delta collapses are increasingly being considered as potential tsunamigenic sources and therefore hazardous for the population and infrastructure along lakeshores. Although historical reports document tsunami events in several lakes in Switzerland, and although the propagation of lake tsunamis has been studied by numerical wave modeling, only little is known about on- and offshore lacustrine tsunami deposits. In Lake Sils, Switzerland, a large prehistoric mass-movement deposit originating from the Isola Delta with a minimum estimated volume of 6.5 × 106 m3 and a basinal thickness of > 6 m in the seismic record has been identified by previous studies and radiocarbon dated to around 700 Common Era. Here, we combine (i) comprehensive sedimentological investigation of sediment cores recovered from the on- and offshore settings, (ii) mineralogical fingerprinting of the inflows from key catchments to characterize sediment provenance, and (iii) numerical tsunami modeling, to test the hypothesis of a tsunamigenic delta collapse in Lake Sils. We observe a clastic event deposit consisting of coarse-grained, fining-upward sand overlying an organic-rich peat deposit in the shallow water. This layer thins and fines landward on the coastal plain. Toward the deeper water (20–40 m), the deposit transforms into a thicker and more heterogeneous sediment package with multiple sequences of fining-upward sand and a well-pronounced clay cap at the top. Radiocarbon dating of the peat underlying the event deposit yields a maximum age of 225–419 calibrated  Common Era. The tsunami models, which indicate wave heights reaching up to 5 m, simulate areas of inundation that coincide with the location of event deposits. Based on our results, we propose that the historically undocumented Isola Delta collapse generated a basin-wide tsunami that inundated the lakeshore, transporting large amounts of unconsolidated sediment along the lakeshore toward the coastal plain and into the deeper lake basin.

scholarly journals Vegetational History of Yellowstone Park as Determined by Pollen Analysis

1978 ◽  
Vol 2 ◽  
pp. 87-91
Author(s):  
George Frison ◽  
Jane Beiswenger
Keyword(s):  
Sediment Cores ◽  
Lake Basin ◽  
Large Lake ◽  
Yellowstone Lake ◽  
North Central ◽  
University Of Utah ◽  
The North ◽  
History Of ◽  
Park Area ◽  
The University

The purpose of this project was to interpret the vegetational history of the Yellowstone Park area by the analysis of pollen contained in sediment cores from four locations in Yellowstone Lake. The cores, collected by Dr. Robert Smith of the University of Utah, were from the north central portion, the west thumb area, the south arm and the southeast arm of the lake. The cores were to be compared to determine pollen variations within the lake. Differences between a small pond and a large lake basin in reflecting climatic change were to be studied by comparing the results with pollen counts from Fifteen Foot Lagoon (Baker, 1976).

scholarly journals Dating North Pacific Abyssal Sediments by Geomagnetic Paleointensity: Implications of Magnetization Carriers, Plio-Pleistocene Climate Change, and Benthic Redox Conditions

2021 ◽  
Vol 9 ◽  
Author(s):  
Wanzhang Wang ◽  
Tilo von Dobeneck ◽  
Thomas Frederichs ◽  
Yang Zhang ◽  
Lester Lembke-Jene ◽  
...  
Keyword(s):  
North Pacific ◽  
Sediment Cores ◽  
Coarse Grained ◽  
Early Pleistocene ◽  
Stratigraphic Correlation ◽  
Major Step ◽  
Late Pliocene ◽  
The North ◽  
Magnetic Carriers ◽  
Pleistocene Climate

Non-carbonaceous abyssal fine-grained sediments cover vast parts of the North Pacific’s deep oceanic basins and gain increasing interests as glacial carbon traps. They are, however, difficult to date at an orbital-scale temporal resolution and still rarely used for paleoceanographic reconstructions. Here, we show that sedimentary records of past geomagnetic field intensity have high potential to improve reversal-based magnetostratigraphic age models. Five sediment cores from Central North Pacific mid-latitudes (39–47°N) and abyssal water depths ranging from 3,900 to 6,100 m were cube-sampled at 23 mm resolution and analyzed by automated standard paleo- and rock magnetic methods, XRF scanning, and electron microscopy. Relative Paleointensity (RPI) records were determined by comparing natural vs. anhysteretic remanent magnetization losses during alternating field demagnetization using a slope method within optimized coercivity windows. The paleomagnetic record delivered well interpretable geomagnetic reversal sequences back to 3 Ma. This age span covers the climate-induced transition from a biogenic magnetite prevalence in the Late Pliocene and Early Pleistocene to a dust-dominated detrital magnetic mineral assemblage since the Mid-Pleistocene. Volcaniclastic materials from concurrent eruptions and gravitational or contouritic sediment re-deposition along extinct seamount flanks provide a further important source of fine- to coarse-grained magnetic carriers. Surprisingly, higher proportions of biogenic vs. detrital magnetite in the late Pliocene correlate with systematically lowered RPI values, which seems to be a consequence of magnetofossil oxidation rather than reductive depletion. Our abyssal RPI records match the astronomically tuned stack of the mostly bathyal Pacific RPI records. While a stratigraphic correlation of rock magnetic and element ratio logs with standard oxygen isotope records was sporadically possible, the RPI minima allowed to establish further stratigraphic tie points at ∼50 kyr intervals. Thus, this RPI-enhanced magnetostratigraphy appears to be a major step forward to reliably date unaltered abyssal North Pacific sediments close to orbital-scale resolution.

scholarly journals The GIK-Archive of sediment core radiographs with documentation

2017 ◽  
Vol 9 (2) ◽  
pp. 969-976
Author(s):  
Hannes Grobe ◽  
Kyaw Winn ◽  
Friedrich Werner ◽  
Amelie Driemel ◽  
Stefanie Schumacher ◽  
...  
Keyword(s):  
Scientific Community ◽  
Sediment Cores ◽  
World Ocean ◽  
X Ray ◽  
Photographic Images ◽  
Careful Preparation ◽  
The World ◽  
Geological Work ◽  
The University ◽  
Data Library

Abstract. The GIK-Archive of radiographs is a collection of X-ray negative and photographic images of sediment cores based on exposures taken since the early 1960s. During four decades of marine geological work at the University of Kiel, Germany, several thousand hours of sampling, careful preparation and X-raying were spent on producing a unique archive of sediment radiographs from several parts of the World Ocean. The archive consists of more than 18 500 exposures on chemical film that were digitized, geo-referenced, supplemented with metadata and archived in the data library PANGAEA®. With this publication, the images have become available open-access for use by the scientific community at https://doi.org/10.1594/PANGAEA.854841.

scholarly journals The GIK-Archive of sediment radiography

2017 ◽  
Author(s):  
Hannes Grobe ◽  
Kyaw Winn ◽  
Friedrich Werner ◽  
Amelie Driemel ◽  
Stefanie Schumacher ◽  
...  
Keyword(s):  
Scientific Community ◽  
Sediment Cores ◽  
World Ocean ◽  
X Ray ◽  
Careful Preparation ◽  
Negative Images ◽  
The World ◽  
Geological Work ◽  
The University ◽  
Data Library

Abstract. The GIK-Archive of radiographs is a collection of X-ray negative images from sediment cores, prepared and exposed since the early 1960s. During four decades of marine geological work at the University of Kiel, Germany, some thousand hours of sampling, careful preparation and x-raying were spent to produce a unique archive of sediment 10 radiographs from several parts of the world ocean. The archive consists of more than 18 500 exposures on chemical film that were digitized, geo-referenced, supplemented with metadata and archived in the data library PANGAEA®. With this publication, the images become available in Open Access for use by the scientific community at https://doi.pangaea.de/10.1594/PANGAEA.854841.

Low temperature x-ray microanalysis of frozen-hydrated tobacco leaves

1984 ◽  
Vol 42 ◽  
pp. 284-285
Author(s):  
S. Edith Taylor ◽  
Patrick Echlin ◽  
May McKoon ◽  
Thomas L. Hayes
Keyword(s):  
Low Temperature ◽  
Lemna Minor ◽  
Root Tips ◽  
Tobacco Leaves ◽  
X Ray ◽  
Whole Cells ◽  
Carbon Coated ◽  
The Right ◽  
Beam Currents ◽  
The University

Low temperature x-ray microanalysis (LTXM) of solid biological materials has been documented for Lemna minor L. root tips. This discussion will be limited to a demonstration of LTXM for measuring relative elemental distributions of P,S,Cl and K species within whole cells of tobacco leaves.Mature Wisconsin-38 tobacco was grown in the greenhouse at the University of California, Berkeley and picked daily from the mid-stalk position (leaf #9). The tissue was excised from the right of the mid rib and rapidly frozen in liquid nitrogen slush. It was then placed into an Amray biochamber and maintained at 103K. Fracture faces of the tissue were prepared and carbon-coated in the biochamber. The prepared sample was transferred from the biochamber to the Amray 1000A SEM equipped with a cold stage to maintain low temperatures at 103K. Analyses were performed using a tungsten source with accelerating voltages of 17.5 to 20 KV and beam currents from 1-2nA.

Imaging of Al-Li-Cu alloys with a Scanning Ion Microprobe

1990 ◽  
Vol 48 (2) ◽  
pp. 314-315
Author(s):  
K.K. Soni ◽  
D.B. Williams ◽  
J.M. Chabala ◽  
R. Levi-Setti ◽  
D.E. Newbury
Keyword(s):  
Mass Spectrometry ◽  
Secondary Ion Mass Spectrometry ◽  
Equilibrium Phase ◽  
Icosahedral Symmetry ◽  
Ion Microprobe ◽  
X Ray ◽  
Cu Alloys ◽  
Two Phases ◽  
The University ◽  
Secondary Ion

In contrast to the inability of x-ray microanalysis to detect Li, secondary ion mass spectrometry (SIMS) generates a very strong Li+ signal. The latter’s potential was recently exploited by Williams et al. in the study of binary Al-Li alloys. The present study of Al-Li-Cu was done using the high resolution scanning ion microprobe (SIM) at the University of Chicago (UC). The UC SIM employs a 40 keV, ∼70 nm diameter Ga+ probe extracted from a liquid Ga source, which is scanned over areas smaller than 160×160 μm2 using a 512×512 raster. During this experiment, the sample was held at 2 × 10-8 torr.In the Al-Li-Cu system, two phases of major importance are T1 and T2, with nominal compositions of Al2LiCu and Al6Li3Cu respectively. In commercial alloys, T1 develops a plate-like structure with a thickness <∼2 nm and is therefore inaccessible to conventional microanalytical techniques. T2 is the equilibrium phase with apparent icosahedral symmetry and its presence is undesirable in industrial alloys.

scholarly journals Effects of Macrofaunal Recolonization on Biogeochemical Processes and Microbiota—A Mesocosm Study

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1599
Author(s):  
Annika Fiskal ◽  
Aixala Gaillard ◽  
Sebastien Giroud ◽  
Dejan Malcic ◽  
Prachi Joshi ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Bottom Water ◽  
Surface Sediments ◽  
Sediment Cores ◽  
Lake Basin ◽  
Sediment Properties ◽  
Chironomid Larvae ◽  
Sediment Reworking ◽  
Mesocosm Experiments ◽  
Tubificid Worms

Macroinvertebrates are widespread in lake sediments and alter sedimentary properties through their activity (bioturbation). Understanding the interactions between bioturbation and sediment properties is important given that lakes are important sinks and sources of carbon and nutrients. We studied the biogeochemical impact of macrofauna on surface sediments in 3-month-long mesocosm experiments conducted using sediment cores from a hypoxic, macrofauna-free lake basin. Experimental units consisted of hypoxic controls, oxic treatments, and oxic treatments that were experimentally colonized with chironomid larvae or tubificid worms. Overall, the presence of O2 in bottom water had the strongest geochemical effect and led to oxidation of sediments down to 2 cm depth. Relative to macrofauna-free oxic treatments, chironomid larvae increased sediment pore water concentrations of nitrate and sulfate and lowered porewater concentrations of reduced metals (Fe2+, Mn2+), presumably by burrow ventilation, whereas tubificid worms increased the redox potential, possibly through sediment reworking. Microbial communities were very similar across oxic treatments; however, the fractions of α-, β-, and γ-Proteobacteria and Sphingobacteriia increased, whereas those of Actinobacteria, Planctomycetes, and Omnitrophica decreased compared to hypoxic controls. Sediment microbial communities were, moreover, distinct from those of macrofaunal tubes or feces. We suggest that, under the conditions studied, bottom water oxygenation has a stronger biogeochemical impact on lacustrine surface sediments than macrofaunal bioturbation.

Dalnegroite, Tl5–xPb2x(As,Sb)2l–xS34, a new thallium sulphosalt from Lengenbach quarry, Binntal, Switzerland

2009 ◽  
Vol 73 (6) ◽  
pp. 1027-1032 ◽  
Author(s):  
F. Nestola ◽  
A. Guastoni ◽  
L. Bindi ◽  
L. Secco
Keyword(s):  
Polarized Light ◽  
New Mineral ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elemental Concentrations ◽  
Reflected Light ◽  
Mohs Hardness ◽  
The Mean ◽  
The University ◽  
Probable Space

AbstractDalnegroite, ideally Tl4Pb2(As12Sb8)Σ20S34, is a new mineral from Lengenbach, Binntal, Switzerland. It occurs as anhedral to subhedral grains up to 200 μm across, closely associated with realgar, pyrite, Sb-rich seligmanite in a gangue of dolomite. Dalnegroite is opaque with a submetallic lustre and shows a brownish-red streak. It is brittle; the Vickers hardness (VHN25) is 87 kg mm-2(range: 69—101) (Mohs hardness ∼3—3½). In reflected light, dalnegroite is highly bireflectant and weakly pleochroic, from white to a slightly greenish-grey. In cross-polarized light, it is highly anisotropic with bluish to green rotation tints and red internal reflections.According to chemical and X-ray diffraction data, dalnegroite appears to be isotypic with chabournéite, Tl5-xPb2x(Sb,As)21-xS34. It is triclinic, probable space groupP1, witha= 16.217(7) Å,b= 42.544(9) Å,c= 8.557(4) Å, α = 95.72(4)°, β = 90.25(4)°, γ = 96.78(4)°,V= 5832(4) Å3,Z= 4.The nine strongest powder-diffraction lines [d(Å) (I/I0) (hkl)] are: 3.927 (100) (10 0); 3.775 (45) (22); 3.685 (45) (60); 3.620 (50) (440); 3.124 (50) (2); 2.929 (60) (42); 2.850 (70) (42); 2.579 (45) (02); 2.097 (60) (024). The mean of 11 electron microprobe analyses gave elemental concentrations as follows: Pb 10.09(1) wt.%, Tl 20.36(1), Sb 23.95(1), As 21.33(8), S 26.16(8), totalling 101.95 wt.%, corresponding to Tl4.15Pb2.03(As11.86Sb8.20)S34. The new mineral is named for Alberto Dal Negro, Professor in Mineralogy and Crystallography at the University of Padova since 1976.

Sign in / Sign up

Export Citation Format

Share Document