Seismic stratigraphy of the late Quaternary sedimentary infill of Lac d'Armor (Kerguelen archipelago): a record of glacier retreat, sedimentary mass wasting and southern Westerly intensification

2012 ◽  
Vol 24 (6) ◽  
pp. 608-618 ◽  
Author(s):  
Katrien Heirman ◽  
Marc De Batist ◽  
Fabien Arnaud ◽  
Jacques-Louis De Beaulieu
Keyword(s):  
Late Quaternary ◽  
Seismic Stratigraphy ◽  
Seismic Facies ◽  
Lake Basin ◽  
Last Deglaciation ◽  
Seismic Profiles ◽  
Reflection Seismic ◽  
Dense Grid ◽  
Sedimentary Mass ◽  
Kerguelen Archipelago

AbstractLac d'Armor (49°27′S, 69°42′E) is a medium-sized, fjord-type lake located on the ‘Grande Terre’ island of the Kerguelen archipelago. A dense grid of high-resolution reflection seismic profiles was collected from this lake basin. The seismic stratigraphic facies reveal a last deglaciation to Holocene infill comparable to the seismic facies found in other glacigenic lakes all over the world. Remarkable features in the seismic stratigraphy are mounded structures found at the southern edge of both sub-basins. The sediment mounds can be interpreted as sediment drifts created by wind-induced bottom currents. The onset of the build-up of these drifts initiated at some point in the Holocene and indicates a strengthening of the southern Westerlies, which are currently the dominant winds on this island.

scholarly journals Reflexně seismický výzkum pozdně kenozoické zlomové tektoniky na vybraných lokalitách hornomoravského úvalu

2020 ◽  
Vol 27 (1-2) ◽  
Author(s):  
Ondřej Bábek ◽  
Zuzana Lenďáková ◽  
Tamás Tóth ◽  
Daniel Šimíček ◽  
Ondřej Koukal
Keyword(s):  
Low Cost ◽  
Seismic Facies ◽  
Gravity Gradients ◽  
Seismic Profiles ◽  
Low Velocity ◽  
Shallow Subsurface ◽  
Static Correction ◽  
Reflection Seismic ◽  
Weight Drop ◽  
Siliciclastic Sediments

We measured shallow reflection seismic profiles across the assumed faults in the Late Cenozoic (Pliocene – Holocene) Upper Morava Basin (UMB). The faults in the UMB are indicated by horst-and-graben morphology, differential thickness of Pliocene and Quaternary siliciclastic sediments, considerable gravity gradients a present-day seismicity. Four seismic lines, 380 to 860 m long (fixed geophone spread) were designed to cross the assumed faults at three sites, Mezice, Drahlov and Výšovice. The data were acquired by 24-channel ABEM Terraloc Mk-8 seismic system with PEG-40 accelerated weight drop source and processed by Sandmaier ReflexW and Halliburton Landmark ProMax® seismic processing software. The processing included application of filters (DC shift, scaled windowgain, bandpass frequency and muting), stacking using normal moveout constant velocity stack, additional application of subtrack-mean (dewow) filter, topographic correction and low velocity layer static correction. Distinct reflectors were detected up to 400 ms TWT, which corresponds to maximum depth of 280 and 350 m at 1400 and 1750 km.s-1 velocities, respectively. The observed reflection patterns were classified into three seismic facies, which were interpreted as crystalline rocks (Brunovistulicum) and/or well consolidated Paleozoic sedimentary rocks (SF1), unconsolidated Quaternary siliciclastic sediments (SF2) and semi-consolidated Neogene clays (SF3) based on the cores drilled in their close vicinity. Distinct faults were observed at the Drahlov and Výšovice 2 profile, which coincided with the observed topographic steps between the horsts and grabens. Presence of the fault at the Drahlov profile separating the Hněvotín Horst from the Lutín Graben was demonstrated by independent electrical resistivity tomography profile. On the other hand, another topographic step at the Mezice profile, between the Hněvotín Horst and Olomouc Graben, does not correspond to any seismic indication of a fault. The reflection seismic proved to be useful and relatively low-cost method to visualize the shallow subsurface geology in the Upper Morava Basin.

scholarly journals Seismic stratigraphy and sedimentary architecture of the Chalk Group in south-west Denmark

1969 ◽  
Vol 31 ◽  
pp. 23-26 ◽  
Author(s):  
Connie Larsen ◽  
Jon Ineson ◽  
Lars Ole Boldreel
Keyword(s):  
Geothermal Energy ◽  
Seismic Stratigraphy ◽  
Seismic Profiles ◽  
Energy Potential ◽  
Reflection Seismic ◽  
South West ◽  
Architectural Features ◽  
Sedimentary Architecture ◽  
The University ◽  
German Basin

The Chalk Group is ubiquitous in the subsurface of the Danish Basin and its upper levels are exposed locally onshore, most notably in eastern Denmark. Although many subsurface studies have been made of the group in the Danish Basin, most of these have been in the eastern part of Denmark (e.g. Esmerode et al. 2007; Surlyk & Lykke-Andersen 2007) whereas the stratigraphy and character of the Chalk Group in the western onshore region is less well-known. The work described here was undertaken as a BSc project at the Department of Geosciences and Natural Resource Mangement at the University of Copenhagen by the first author as part of regional seismic mapping work contributing to an evaluation of the geothermal energy potential in Denmark. The aim of this paper is to present a summary of the key results of the study. We have subdivided and mapped the distribution of the Chalk Group in the northern North German Basin and the south-western Danish Basin based on digital reflection seismic profiles. We also highlight seismic architectural features that testify to periods of active bottom currents.

scholarly journals Tertiary development of the Faeroe-Rockall Plateau based on reflection seismic data

1994 ◽  
Vol 41 ◽  
pp. 162-180
Author(s):  
L O. Baldreel ◽  
M.S. Andersen
Keyword(s):  
Seismic Data ◽  
Seismic Facies ◽  
Early Eocene ◽  
Ne Atlantic ◽  
Seismic Profiles ◽  
Norwegian Sea ◽  
Reflection Seismic ◽  
The North ◽  
Rockall Trough ◽  
Ne Atlantic Ocean

The Faeroe-Rockall Plateau is located in the NE Atlantic Ocean between Iceland and Scotland and is characterized by a late Paleocene-early Eocene basalt cover, which was extruded in association with the incipient opening of the NE Atlantic. The Faeroe-Rockall Plateau is separated from the NW European continental shelf by the Rockall Trough and the Faeroe­Shetland Channel, whose nature and age is still debated. Reflector configuration within the basalt allows volcanic seismic facies inteipretation to be carried out. The thickness of the basalt cover is estimated from reflection seismic data. Subbasalt geological structures are identified below subaerially extruded basalt on recently acquired as well as reprocessed seismic profiles. Overlying the basalt are early Eocene and younger Sediments. The distribution of these sedi- . ments is largely controlled by 1) the topography after the cessation of the volcanism, 2) the post volcanic subsidence of the area which is estimated from the depth to the breakpoints located on prim¥)' volcanic escaipments, 3) the Eocene-Miocene compressional tectonics which formed ridge& and minor basins, and 4) bottom currents of Norwegian Sea Deep Water (NSDW) which in the Neogene flowed into the North Atlantic south of the Greenland-Iceland-Faeroe-Scotland Ridg,e. A considerable part of the NSDW flows east and south of th

Seismic stratigraphy of late Cenozoic sediments in the northern Labrador Sea: a history of bottom circulation and glaciation

1988 ◽  
Vol 25 (12) ◽  
pp. 2059-2074 ◽  
Author(s):  
Robert A. Myers ◽  
David J. W. Piper
Keyword(s):  
High Latitude ◽  
Deep Sea ◽  
Bottom Water ◽  
Late Quaternary ◽  
Seismic Facies ◽  
Early Pleistocene ◽  
Labrador Sea ◽  
Seismic Profiles ◽  
Ocean Drilling Program ◽  
Basin Floor

The seismicstratigraphy of the upper 1 km of sediment in the northern Labrador Sea has been determined from the examination of about 26 000 line kilometres of seismic profiles. Four key reflectors (A to D) have been correlated with Deep Sea Drilling Project (DSDP) and Ocean Drilling Program (ODP) holes and range in age from mid-Pliocene to approximately mid-Pleistocene. Ten seismic facies have been distinguished and are interpreted as resulting from slope progradation, turbidite deposition in channels and on the basin floor, and widespread contourite deposition.Tertiary sediments are predominantly hemipelagic or contourite, but in the mid-Pliocene, turbidite deposition began in the northeast Labrador Basin, which might reflect either Greenland glaciation or lowering of sea level. At the same time, widespread erosion and buildup of drift deposits indicate that there was an intensification of bottom-water circulation, probably reflecting high-latitude cooling. This was followed by a return to less dynamic conditions as increased sea-ice cover reduced bottom-water generation in high-latitude seas. A turbidite deep-sea fan developed off Hudson Strait in the Early Pleistocene. In the mid- and late Quaternary, there was a major increase in the supply of turbidites from the Labrador margin, accompanied by the development of an extensive channel system on the continental margin. This was a consequence of glacial ice sheets extending to the top of the continental slope and discharging sediment directly to deep water.

scholarly journals Geophysical imaging of permafrost in the SW Svalbard – the result of two high arctic expeditions to Spitsbergen

2020 ◽  
Author(s):  
Mariusz Majdanski ◽  
Artur Marciniak ◽  
Bartosz Owoc ◽  
Wojciech Dobiński ◽  
Tomasz Wawrzyniak ◽  
...  
Keyword(s):  
Surface Waves ◽  
Active Layer ◽  
High Arctic ◽  
The Arctic ◽  
Seismic Profiles ◽  
Frozen Ground ◽  
Near Surface ◽  
Seismic Processing ◽  
Reflection Seismic ◽  
Sea Coast

<p>The Arctic regions are the place of the fastest observed climate change. One of the indicators of such evolution are changes occurring in the glaciers and the subsurface in the permafrost. The active layer of the permafrost as the shallowest one is well measured by multiple geophysical techniques and in-situ measurements.</p><p>Two high arctic expeditions have been organized to use seismic methods to recognize the shape of the permafrost in two seasons: with the unfrozen ground (October 2017) and frozen ground (April 2018). Two seismic profiles have been designed to visualize the shape of permafrost between the sea coast and the slope of the mountain, and at the front of a retreating glacier. For measurements, a stand-alone seismic stations has been used with accelerated weight drop with in-house modifications and timing system. Seismic profiles were acquired in a time-lapse manner and were supported with GPR and ERT measurements, and continuous temperature monitoring in shallow boreholes.</p><p>Joint interpretation of seismic and auxiliary data using Multichannel analysis of surface waves, First arrival travel-time tomography and Reflection imaging show clear seasonal changes affecting the active layer where P-wave velocities are changing from 3500 to 5200 m/s. This confirms the laboratory measurements showing doubling the seismic velocity of water-filled high-porosity rocks when frozen. The same laboratory study shows significant (>10%) increase of velocity in frozen low porosity rocks, that should be easily visible in seismic.</p><p>In the reflection seismic processing, the most critical part was a detailed front mute to eliminate refracted arrivals spoiling wide-angle near-surface reflections. Those long offset refractions were however used to estimate near-surface velocities further used in reflection processing. In the reflection seismic image, a horizontal reflection was traced at the depth of 120 m at the sea coast deepening to the depth of 300 m near the mountain.</p><p>Additionally, an optimal set of seismic parameters has been established, clearly showing a significantly higher signal to noise ratio in case of frozen ground conditions even with the snow cover. Moreover, logistics in the frozen conditions are much easier and a lack of surface waves recorded in the snow buried geophones makes the seismic processing simpler.</p><p>Acknowledgements               </p><p>This research was funded by the National Science Centre, Poland (NCN) Grant UMO-2015/21/B/ST10/02509.</p>

scholarly journals Lithoprobe-Phase 1: southern Vancouver Island: preliminary analyses of reflection seismic profiles and surface geological studies

1985 ◽  
Author(s):  
C J Yorath ◽  
R M Clowes ◽  
A G Green ◽  
A Sutherland-Brown ◽  
M T Brandon ◽  
...  
Keyword(s):  
Phase 1 ◽  
Vancouver Island ◽  
Seismic Profiles ◽  
Reflection Seismic

scholarly journals Structural analysis of S-wave seismics around an urban sinkhole; evidence of enhanced subrosion in a strike-slip fault zone

2017 ◽  
Author(s):  
Sonja H. Wadas ◽  
David C. Tanner ◽  
Ulrich Polom ◽  
Charlotte M. Krawczyk
Keyword(s):  
Strike Slip ◽  
Strike Slip Fault ◽  
Key Factors ◽  
S Wave ◽  
Seismic Profiles ◽  
Reflection Seismic ◽  
Dextral Strike Slip Fault ◽  
Seismic Sections ◽  
The Town ◽  
Dextral Strike Slip

Abstract. In November 2010, a large sinkhole opened up in the urban area of Schmalkalden, Germany. To determine the key factors which benefited the development of this collapse structure and therefore the subrosion, we carried out several shear wave reflection seismic profiles around the sinkhole. In the seismic sections we see evidence of the Mesozoic tectonic movement, in the form of a NW–SE striking, dextral strike-slip fault, known as the Heßleser Fault, which faulted and fractured the subsurface below the town. The strike-slip faulting created a zone of small blocks (

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