The shape and infill of the Basadingen overdeepened glacial valley from P-wave seismic reflections

2021 ◽  
Author(s):  
Anna-Catharina Brandt ◽  
David C. Tanner ◽  
Hermann Buness ◽  
Thomas Burschil ◽  
Gerald Gabriel
Keyword(s):  
P Wave ◽  
Borehole Data ◽  
North East ◽  
The North ◽  
Glacier Valley ◽  
Sedimentary System ◽  
Climatic History ◽  
The Alps ◽  
Seismic Reflections ◽  
Seismic Images

<p><span>Overdeepened valleys in the Alps allow to probe the glacial sedimentation record, which in turn can illuminate the climatic history. In particular, seismic reflections can be used to extend punctual borehole data (for instance a number of boreholes are to be drilled into Alpine glacial overdeepened valleys as part of the DOVE ICDP project) in the second dimension or even survey a region before drilling begins. Thus, we use detailed, 2-D seismic P-wave profiles to reveal the shape and infill of an overdeepened Rhine glacier valley in the area of Basadingen, near to the German/Swiss border. We acquired two profiles nearly perpendicular to the valley strike, approximately 500 m apart. The first profile was 1246 m long, and consisted of a single spread of 624 geophones. The second profile was 1120 m long and was acquired using 200 3-component geophones using a roll-along method. For both profiles we used a vibro-source with a 12 s linear sweep of 20-240 Hz at every second geophone (two metre spacing), which produced a high fold.</span></p><p><span>Both seismic images reveal that the overdeepened basin at this location is asymmetrical and circa 260 m deep, although the deepest part (220</span><span> </span><span>m wide) covers only a small portion of the broader main valley. The infill is characterised by at least three unconformities and distinct onlap and erosive boundaries between the sedimentary units. We interpret the infill to represent a highly dynamic sedimentary system. The lower part, within the deepest part of the basin is filled with chaotic sediments and slumping. Above a major unconformity, the upper part contains strongly-dipping reflectors that probably represent a prograding point-bar in a glacio-fluviatile environment that migrated toward the north-east. Beneath the deepest part of the basin we see evidence for faults in the Tertiary Molasse basement, which correlate with known faults at the surface. The faults most likely caused the valley to be sited at this location and they were probably also the cause of the ‘valley in valley’ shape.</span></p><p><span>A new DOVE research borehole will be drilled in the centre of the valley in 2021. This will bring more light on the sedimentary history and OSL-dating of the material will bracket the timing of the infill. </span></p>

scholarly journals Late Holocene temperature variability in Tasmania inferred from borehole temperature data

2017 ◽  
Vol 13 (6) ◽  
pp. 559-572 ◽  
Author(s):  
Asadusjjaman Suman ◽  
Fiona Dyer ◽  
Duanne White
Keyword(s):  
East Coast ◽  
Past Century ◽  
Borehole Data ◽  
Depth Profiles ◽  
The Past ◽  
North East ◽  
The North ◽  
Borehole Temperature ◽  
Temperature Depth

Abstract. Thirty-six borehole temperature–depth profiles were analysed to reconstruct the ground surface temperature history (GSTH) of eastern Tasmania for the past 5 centuries. We used the singular value decomposition method to invert borehole temperatures to produce temperature histories. The quality of borehole data was classified as high or low based on model misfit. The quality of the borehole data was not dependent on topography or land use. Analysis reveals that three to five high-quality borehole temperature–depth profiles were adequate to reconstruct robust paleotemperature records from any area. Average GSTH reconstructed from Tasmanian boreholes shows temperature increases about 1.2 ± 0.2 °C during the past 5 centuries. Reconstructed temperatures were consistent with meteorological records and other proxy records from Tasmania during their period of overlap. Temperature changes were greatest around the north-east coast and decreased towards the centre of Tasmania. The extension of the East Australian Current (EAC) further south and its strengthening around the north-east coast of Tasmania over the past century was considered a prime driver of warmer temperatures observed in north-east Tasmania.

scholarly journals Project Tor: Deep lithospheric variation across the Sorgenfrei-Tornquist Zone, Southern Scandinavia

1999 ◽  
Vol 46 ◽  
pp. 13-24
Author(s):  
Trine Pedersen ◽  
Søren Gregersen
Keyword(s):  
Upper Mantle ◽  
Surface Expression ◽  
P Wave ◽  
Northern Germany ◽  
Rectangular Array ◽  
Teleseismic Tomography ◽  
North East ◽  
The North ◽  
P Wave Velocity ◽  
Southern Scandinavia

The Tor project makes use of teleseismic tomography across the Sorgenfrei-Tornquist Zone and has now revealed significant variations in the deep lithosphere under northern Germany, Denmark and southern Sweden. Here we present the first interpretations of P-wave traveltime anomalies from the Tor project. The project utilised 120 seismographs placed in a rectangular array, the largest seismic antenna so far used in Europe, for half a year in the period 1996–1997. The present investigation establishes a 3D crustal/upper mantle model of the P-wave velocity based on existing data. A picture of the crustal influence on the seismic P-wave rays is established by ray tracing through the model. When this is subtracted from that observed by the Tor array, a picture of the influence of the lower lithosphere/asthenosphere system emerges. For several earthquakes it is shown that the observed P-wave traveltime anomalies of nearly 2 seconds can be divided almost equally between known crustal effects and lower lithosphere/asthenosphere differences. The transition appears gradual from most directions but for rays coming from the north-east direction the transition appears sharper. This means that the broad scale deep lithosphere transition is gradual with the sharpest discontinuity plane dipping down steeply in a north-easterly direction from the Sorgenfrei-Tornquist Zone. Based on existing knowledge of the area we conclude that the transition from thin to thick lithosphere occurs within a short distance, and that the lithosphere/asthenosphere boundary dips steeply down from the surface expression of the Sorgenfrei-Tornquist Zone.

Structure of the crust and upper mantle in the ALPS from the phase velocity of Rayleigh waves

1966 ◽  
Vol 56 (5) ◽  
pp. 1009-1044 ◽  
Author(s):  
L. Knopoff ◽  
S. Mueller ◽  
W. L. Pilant
Keyword(s):  
Phase Velocity ◽  
Upper Mantle ◽  
Lower Boundary ◽  
P Wave ◽  
Low Velocity ◽  
Crust And Upper Mantle ◽  
The North ◽  
Method Effects ◽  
The Alps

Abstract The phase velocity method has been applied to the problem of the determination of the crust and upper mantle under the western Alpine crest and in the Alpine foreland to the north. An extensive data processing package has been designed so that Fourier analysis is applied to the determination of phase velocities, rather than the more usual peak-and-trough method. Effects of contamination by multipath interference, manifested in beats, can be minimized. Advantage is made of apparent azimuthal variations in phase velocity to yield a further refinement in the method whereby the tripartite results are assigned to discrete lines in the network rather than to the area swept out by the wave front. The results show that a well-developed low-velocity channel for S is found throughout the region with a velocity of S in the channel of 4.2 km/sec. The top of the channel is at about 80 km depth. A new analysis of P-wave data shows a likely horizon for reflections at 220 km; this is taken to be the depth of the lower boundary to the channel. The mean P-wave velocity in the lower crust is at least as high as 6.7 km/sec. The crustal and upper mantle structure vary significantly over relatively short distances. The Mohorovičić discontinuity is deepest under the crest of the Alps and shoals to the north and west; a well developed root has been found.

scholarly journals The Occurrence of Palæoliths in North-East Lancashire

1915 ◽  
Vol 2 (1) ◽  
pp. 61-71
Author(s):  
T. E. Nuttall
Keyword(s):  
Great Britain ◽  
Ice Sheet ◽  
Ice Age ◽  
Interglacial Period ◽  
The South ◽  
North East ◽  
The North ◽  
Southern Margin ◽  
Imaginary Line ◽  
The Alps

For many years it was postulated that an ice sheet had covered the north and west of Great Britain during the period when Palæolithic man lived and made his flint implements in the south and east of England. It was taught that the southern margin of this ice sheet corresponded in the main with an imaginary line stretching from about the mouth of the Severn to the Wash, or, as others claimed, from the mouth of the Severn to the mouth of the Thames. These views were held to be supported by the fact that very few palæoliths had been found north of the above-mentioned line. As years passed, however, new facts testifying to the lengthy duration of the Palæolithic period slowly accumulated, and knowledge respecting the great Ice Age gradually increased. True, many and divergent views have been advanced respecting the several phases of the Ice Age as these concern Lancashire and the north of England generally. Some glacialists hold that the Ice Age there, as also in the Alps, was broken up into several complete cycles consisting of a number of glaciations with a corresponding number of interglacial periods. Others believe that there was only one interglacial period in the north of England.

scholarly journals High resolution reflection seismic profiling over the Tjellefonna fault in the Møre-Trøndelag Fault Complex, Norway

2012 ◽  
Vol 4 (1) ◽  
pp. 241-278 ◽  
Author(s):  
E. Lundberg ◽  
C. Juhlin ◽  
A. Nasuti
Keyword(s):  
P Wave ◽  
The South ◽  
Seismic Profiles ◽  
Surface Geometry ◽  
Secondary Fracture ◽  
Near Surface ◽  
North West ◽  
Reflection Seismic ◽  
North East ◽  
The North

Abstract. The Møre-Trøndelag Fault Complex (MTFC) is one of the most prominent fault zones of Norway, both onshore and offshore. In spite of its importance, very little is known of the deeper structure of the individual fault segments comprising the fault complex. Most seismic lines have been recorded offshore or focused on deeper structures. This paper presents results from two reflection seismic profiles, located on each side of the Tingvollfjord, acquired over the Tjellefonna fault in the south-eastern part of the MTFC. Possible kilometer scale vertical offsets reflecting, large scale north-west dipping normal faulting separating the high topography to the south-east from lower topography to the north-west have been proposed for the Tjellefonna fault. In this study, however, the Tjellefonna fault is interpreted to dip approximately 50–60° towards the south-east to depths of at least 1.4 km. Travel-time modeling of reflections associated with the fault was used to establish the geometry of the fault structure at depth and detailed analysis of first P-wave arrivals in shot-gathers together with resistivity profiles were used to define the near surface geometry of the fault zone. A continuation of the structure on the north-eastern side of the Tingvollfjord is suggested by correlation of an in strike direction P-S converted reflection (generated by a fracture zone) seen on the reflection data from that side of the Tingvollfjord. The reflection seismic data correlate well with resistivity profiles and recently published near surface geophysical data. A highly reflective package forming a gentle antiform structure was also identified on both seismic profiles. The structure may be an important boundary within the gneissic basement rocks of the Western Gneiss Region. The Fold Hinge Line is parallel with the Tjellefonna fault trace while the topographic lineament diverges, following secondary fracture zones towards north-east.

The Compression and Stretching of Continental Layers

1937 ◽  
Vol 74 (2) ◽  
pp. 84-85
Author(s):  
P. R. Thompson
Keyword(s):  
North America ◽  
The State ◽  
Tensile Stresses ◽  
North East ◽  
The North ◽  
The Alps ◽  
State Of Tension

The forces which produced the folds of the Alps, and caused waves of compression to be transmitted as far as the Weald, may have been sufficiently powerful to start a drift displacement of Europe towards the north-east. As there does not appear to have been any similar compression in North America, a north-easterly movement of Europe would have caused shear in the strong continental layers which are considered to have connected the two continents. Tensile stresses would probably have arisen in these layers, unless the layers had begun to thin out before the state of tension was reached. There would have been a limit to the extent to which thinning could have proceeded, since a certain thickness of rock would have been needed to produce the necessary stress-differences. This thinning out process may have come into operation, except in a number of kilometres immediately below the surface, where tensile stresses may have arisen as drift continued. Under these circumstances the uppermost part of the crust would have sagged upon the thinning region, nd been broken up by a system of tension fractures.

scholarly journals Late Holocene temperature variability in Tasmania inferred from borehole temperature data

2016 ◽  
Author(s):  
Asadusjjaman Suman ◽  
Fiona Dyer ◽  
Duanne White
Keyword(s):  
East Coast ◽  
Temperature History ◽  
Borehole Data ◽  
Depth Profiles ◽  
The Past ◽  
North East ◽  
The North ◽  
Borehole Temperature ◽  
Temperature Depth

Abstract. Thirty six borehole temperature depth profiles were analysed to reconstruct the Ground Surface Temperature History (GSTH) from eastern Tasmania for the past five centuries. We used the Singular Value Decomposition method to invert borehole temperatures to produce temperature histories. The quality of borehole data was classified as high or low based on model misfit. The quality of the borehole data was not dependent on topography, or land use. Analysis reveals that 3–5 high quality borehole temperature depth profiles were adequate to reconstruct robust paleotemperature records from any area. Temperature changes were greatest around the north east coast and decreases towards midland of Tasmania. Warm East Australian Current (EAC) flow towards north east coast of Tasmania during summer was considered a prime driver of warmer temperatures observed for the north east coast. Average, GSTH reconstructed from Tasmanian boreholes shows temperature increases about 1.2 ± 0.2 °C during the past five centuries. Some boreholes show temperature cooling in the beginning of 20th Century that may be an indication of late LIA response in Tasmania. Reconstructed temperatures were consistent with meteorological records and other proxy records from Tasmania during their period of overlap.

scholarly journals Partitioning of snowy and rainy precipitation in a case of a north Adriatic frontal passage

2006 ◽  
Vol 7 ◽  
pp. 279-284 ◽  
Author(s):  
M. Monai ◽  
A. M. Rossa ◽  
A. C. Bonan
Keyword(s):  
Adriatic Sea ◽  
Weather Prediction ◽  
Numerical Weather Prediction Model ◽  
Limited Area ◽  
Italian Region ◽  
Cold Air ◽  
The Road ◽  
North East ◽  
The North ◽  
The Alps

Abstract. A case of snow fall in the plains of the Northern Italian region Veneto is presented from a forecasters' perspective. Contrasting forecast guidance came from the ECMWF global model and the limited area model LAMI. The former showed a marked warm-moist Sirocco flow coming from the Adriatic Sea onto the coast at all levels, the latter discerned a distinct cold air flow from the north-east along the foothills of the Alps. The integrated observing network of the Centro Meteorologico di Teolo ARPA Veneto revealed this cold-air structure and helped the forecaster in the choice of the forecast and underpin the snowfall alert to the road authorities. It is argued that this feature is a crucial element for the occurrence of snowfall over the Veneto plains, and that the high-resolution numerical weather prediction model was essential in describing this mesoscale feature. The nature of the north-easterly flow is thought to be a combination of a Bora like flow and a barrier jet induced by flow blocking by the Alps.

scholarly journals FOREST STANDS FROM ACCUMULATION AND NATURAL LAKES SLOPES FROM THE SOUTHERN CARPATHIANS

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Lucian Dincă ◽  
Voichita Timis-Gansac ◽  
Iuliana Gabriela Breaban
Keyword(s):  
Alnus Glutinosa ◽  
Point Of View ◽  
Site Conditions ◽  
Water Protection ◽  
North East ◽  
Natural Lakes ◽  
The North ◽  
Fagus Sylvatica L ◽  
The Alps ◽  
Southern Carpathians

The Southern Carpathians are situated in the central part of Romania, between Prahova Valley and the Danube, being the highest and most massive mountains from the Romanian Carpahtians. The relief and vegetation are similar to the Alps. These mountains conserve the most representative glaciar relief from Romania, with cuaternar glaciar tracks. Some of its peaks, namely Moldoveanu, Negoiu, Parângul Mare and Peleaga exceed 2500 m. From its total 217.889 ha occupied by forests with water protection functions, the forests located on lake slopes occupy 9.746 ha, namely 5%. The forests from this area are composed of spruce (Picea abies L.H. Karst) and beech (Fagus sylvatica L.), accompanied by other species such as birch (Alnus glutinosa, L., Gaertn.) and pine (Pinus sp.). From the point of view of the field's orography, these forests are located on lands with an middle inclination on all exposition categories, but predominantly on the North-East, one at an average altitude of 1050 m. From the point of view of site conditions, the characteristic flora type is Asperula-Dentaria, while the main soils are dystric cambisol and eutric cambisol.

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