scholarly journals RE-ORIENTANTION METHODS OF CORE SAMPLES: IMPLICATIONS TO SEDIMENT CORES FROM N. GREECE

2004 ◽  
Vol 36 (3) ◽  
pp. 1194
Author(s):  
Ε. Αηδονά ◽  
Δ. Κοντοπούλου ◽  
R. Scholger
Keyword(s):  
Sediment Cores ◽  
Initial Position ◽  
The Core ◽  
Core Samples ◽  
The North ◽  
Magnetic Components ◽  
Viscous Component ◽  
Orientation Method

The different methods of re-orientation of core samples are discussed in the present study. In order to obtain results from core samples concerning the direction of the formation, their permeability and their anisotropy, it is essential first to bring all the pieces of the core into their initial position with regard to the North and to the horizontal (in-situ). In this study we emphasize particularly to the palaeomagnetic technique. This re-orientation method uses the magnetic components of the rocks (especially the viscous component) in order to determine the direction with regard to the North (declination). Also, the anisotropy method which helps us to correct the angle to the horizontal (inclination) is described here. Finally we applied the last two methods in non-oriented core samples from N. Greece and the significant importance of the re-orientation techniques to the palaeomagnetic studies is shown.

scholarly journals North Atlantic warming over six decades drives decreases in krill abundance with no associated range shift

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Martin Edwards ◽  
Pierre Hélaouët ◽  
Eric Goberville ◽  
Alistair Lindley ◽  
Geraint A. Tarling ◽  
...  
Keyword(s):  
North Atlantic ◽  
Range Shift ◽  
The Core ◽  
Krill Abundance ◽  
The North ◽  
Living Space ◽  
Warming Climate ◽  
Two Temperatures ◽  
The North Atlantic

AbstractIn the North Atlantic, euphausiids (krill) form a major link between primary production and predators including commercially exploited fish. This basin is warming very rapidly, with species expected to shift northwards following their thermal tolerances. Here we show, however, that there has been a 50% decline in surface krill abundance over the last 60 years that occurred in situ, with no associated range shift. While we relate these changes to the warming climate, our study is the first to document an in situ squeeze on living space within this system. The warmer isotherms are shifting measurably northwards but cooler isotherms have remained relatively static, stalled by the subpolar fronts in the NW Atlantic. Consequently the two temperatures defining the core of krill distribution (7–13 °C) were 8° of latitude apart 60 years ago but are presently only 4° apart. Over the 60 year period the core latitudinal distribution of euphausiids has remained relatively stable so a ‘habitat squeeze’, with loss of 4° of latitude in living space, could explain the decline in krill. This highlights that, as the temperature warms, not all species can track isotherms and shift northward at the same rate with both losers and winners emerging under the ‘Atlantification’ of the sub-Arctic.

scholarly journals A stratigraphy-based method for reconstructing ice core orientation

2021 ◽  
Author(s):  
Julien Westhoff ◽  
Nicolas Stoll ◽  
Steven Franke ◽  
Ilka Weikusat ◽  
Paul Bons ◽  
...  
Keyword(s):  
Physical Properties ◽  
Ice Core ◽  
Ice Cores ◽  
The Core ◽  
Ice Stream ◽  
Orientation Method

<p>Ever since the first deep ice cores were drilled, it has been a challenge to determine their original, in-situ orientation. In general, the orientation of an ice core is lost as the drill is free to rotate during transport to the surface. For shallow ice cores, it is usually possible to match the adjacent core breaks, which preserves the orientation of the ice column. However, this method fails for deep ice cores, such as the EastGRIP ice core in Northeast Greenland. We provide a method to reconstruct ice core orientation using visual stratigraphy and borehole geometry. As the EastGRIP ice core is drilled through the Northeast Greenland Ice Stream, we use information about the directional structures to perform a full geographical re-orientation. We compared the core orientation with logging data from core break matching and the pattern of the stereographic projections of the crystals’c-axis orientations. Both comparisons agree very well with the proposed orientation method. The method works well for 441 out of 451 samples from a depth of 1375–2120 m in the EastGRIP ice core. It can also be applied to other ice cores, providing a better foundation for interpreting physical properties and understanding the flow of ice.</p>

scholarly journals A System for Retrieval and Incubation of Benthic Sediment Cores at In Situ Ambient Pressure and under Controlled or Manipulated Environmental Conditions

2017 ◽  
Vol 34 (5) ◽  
pp. 983-1000 ◽  
Author(s):  
Keith Jackson ◽  
Ursula Witte ◽  
Stewart Chalmers ◽  
Erik Anders ◽  
John Parkes
Keyword(s):  
Deep Sea ◽  
Experimental Approach ◽  
Low Cost ◽  
Ambient Pressure ◽  
Sediment Cores ◽  
Biogeochemical Processes ◽  
Physiological Changes ◽  
The Core ◽  
In Situ Experiments

AbstractThe investigation of benthic biodiversity and biogeochemical processes in the deep sea is complicated by the need to conduct experiments at in situ pressures. Recovery of sediment samples to the surface without maintaining full-depth ambient pressure may damage the organisms that are of interest or cause physiological changes that could influence the processes being studied. It is possible to carry out in situ experiments using remotely operated vehicles (ROVs) or lander systems. However, the costs and complexity of ROV operations are significant and, for both ROVs and landers, the complexity and repeatability of the experiments are subject to the limitations imposed by these platforms. A system is described—the Multi-Autoclave Corer Experiment (MAC-EXP)—that has been developed with the aim of offering a new experimental approach to investigators. The MAC-EXP system is designed to retrieve sediment cores from depths down to 3500 m and to seal them into pressure chambers before being recovered so that they are maintained at their normal ambient pressure. After recovery the core chambers can be connected to a laboratory incubation system that allows for experimentation on the sediment without loss of pressure and under controlled conditions of temperature and oxygen concentration. The system is relatively low cost when compared to ROV systems and can be deployed using methods and equipment similar to those used for routine deployments of small unpressurized multicorers. The results of sea trials are detailed.

scholarly journals A stratigraphy-based method for reconstructing ice core orientation

2020 ◽  
pp. 1-12
Author(s):  
Julien Westhoff ◽  
Nicolas Stoll ◽  
Steven Franke ◽  
Ilka Weikusat ◽  
Paul Bons ◽  
...  
Keyword(s):  
Physical Properties ◽  
Ice Core ◽  
Ice Cores ◽  
The Core ◽  
Ice Stream ◽  
Orientation Method

Abstract Ever since the first deep ice cores were drilled, it has been a challenge to determine their original, in-situ orientation. In general, the orientation of an ice core is lost as the drill is free to rotate during transport to the surface. For shallow ice cores, it is usually possible to match the adjacent core breaks, which preserves the orientation of the ice column. However, this method fails for deep ice cores, such as the EastGRIP ice core in Northeast Greenland. We provide a method to reconstruct ice core orientation using visual stratigraphy and borehole geometry. As the EastGRIP ice core is drilled through the Northeast Greenland Ice Stream, we use information about the directional structures to perform a full geographical re-orientation. We compared the core orientation with logging data from core break matching and the pattern of the stereographic projections of the crystals’ c-axis orientations. Both comparisons agree very well with the proposed orientation method. The method works well for 441 out of 451 samples from a depth of 1375–2120 m in the EastGRIP ice core. It can also be applied to other ice cores, providing a better foundation for interpreting physical properties and understanding the flow of ice.

MAGNETIC ORIENTATION OF BOREHOLE CORES

Geophysics ◽  
1969 ◽  
Vol 34 (5) ◽  
pp. 772-774 ◽  
Author(s):  
M. Fuller
Keyword(s):  
Geomagnetic Field ◽  
Remanent Magnetization ◽  
Standard Procedure ◽  
Natural Remanent Magnetization ◽  
Core Sample ◽  
The Core ◽  
Viscous Component ◽  
Late Tertiary ◽  
Geomagnetic Pole ◽  
Orientation Method

The use of natural remanent magnetization (NRM) to orient boreholes was reported at least thirty years ago (e.g., Lynton, 1938). The method depends upon determining the direction of remanent magnetization of the sample and relating it to the geomagnetic field in which the rock was presumed to have been magnetized. If the NRM faithfully records the relevant geomagnetic field and the field is known, the orientation of the core sample is available. Unfortunately, the ancient geomagnetic pole positions are not, in general, sufficiently well known to make this method particularly successful for rocks that are older than late Tertiary. Moreover, the presence of a weak, viscous component of magnetization parallel to the present geomagnetic field at a given site may produce erroneous results unless it is recognized and eliminated. However, the existence of this component provides another means of orienting the core sample. Isolation of this component might initially appear to be difficult, but it is actually a standard procedure of paleomagnetism; and, in fact, many studies have implicitly demonstrated that the direction of the present geomagnetic field at the sample site is recoverable (e.g., As and Zijderveld, 1958; Zijderveld, 1967). Indeed a number of people have recognized the possibility of using this component to orient borehole samples (e.g., Hargraves, 1969—private communication). The use of this soft viscous component has been advocated recently to distinguish between normal and reversely magnetized rocks in connection with tests of the sea floor spreading hypothesis (Irving and Roy, 1968). Nevertheless, no explicit demonstration of the technique of orienting borehole cores has been published. In the course of paleomagnetic surveys, our demagnetization studies have revealed a number of examples of behavior which makes the orientation method possible. This note describes such behavior and explains how the orientation might be recovered.

Fossil diatoms from the Volga Delta Holocene sediments (Damchik region) as indicators of the paleoecological conditions of sedimentation

2019 ◽  
pp. 270-273
Author(s):  
Yelena I. Shtyrkova ◽  
Yelena I. Polyakova
Keyword(s):  
Nature Reserve ◽  
Diatom Analysis ◽  
Volga Delta ◽  
The Core ◽  
Core Samples ◽  
Holocene Sediments ◽  
Fossil Diatoms

The results of fossil diatoms investigation from the deltaic sediments are presented. Samples were obtained from the core DM-1 and two Holocene outcrops from the Damchik region of the Astrakhan Nature Reserve. In the core samples eight periods of sedimentation based on diatom analysis were identified: the sediments formed in shallow freshwater basins and deltaic channels. The samples from the outcrops were investigated in much greater detail.

Estudio del proceso de lavado de contenedores para eliminar tiempos y movimientos innecesarios, caso: Wash Containers S.A de C.V.

2020 ◽  
pp. 25-36
Author(s):  
Juan Alfredo Lino-Gamiño ◽  
Carlos Méndez-González ◽  
Eduardo José Salazar-Araujo ◽  
Pablo Adrián Magaña-Sánchez
Keyword(s):  
Business Process ◽  
Value Chain ◽  
Process Management ◽  
Core Business ◽  
The Core ◽  
Washing Process ◽  
Overall Performance ◽  
The Times

In the value chain it is important to keep in mind the core business of the company, since it depends largely on the competitiveness of the company and its overall performance, bearing in mind that all business indicators depend on it. In this work we will study the washing process within the company WASH CONTAINERS SA DE CV, to improve the washing processes and in this way reduce times and movements in the process leading the company to reduce costs considerably within the operations company daily, having a more competitive operation and with greater profit margin in its business process. Goals: It Improve the logistics of the movement of containers for washing and with it the core business of the company. Methodology: The action research will be applied applying Business Process Management for the improvement of processes in situ, it will be developed in a certain period of time and with that it will establish an improvement projection. Contribution: The improvement of the times for the disposal of the containers and their subsequent use, allows a better competitiveness and with it the income of the company, on the other hand, the transport companies improve in performance in quantity, quality of disposition and with it their income.

scholarly journals Holocene polynya dynamics and their interaction with oceanic heat transport in northernmost Baffin Bay

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rebecca Jackson ◽  
Anna Bang Kvorning ◽  
Audrey Limoges ◽  
Eleanor Georgiadis ◽  
Steffen M. Olsen ◽  
...  
Keyword(s):  
Sediment Cores ◽  
Active Role ◽  
Atlantic Water ◽  
The Arctic ◽  
Negative Consequences ◽  
Baffin Bay ◽  
The North ◽  
North Water ◽  
History Of ◽  
Ocean Conditions

AbstractBaffin Bay hosts the largest and most productive of the Arctic polynyas: the North Water (NOW). Despite its significance and active role in water mass formation, the history of the NOW beyond the observational era remains poorly known. We reconcile the previously unassessed relationship between long-term NOW dynamics and ocean conditions by applying a multiproxy approach to two marine sediment cores from the region that, together, span the Holocene. Declining influence of Atlantic Water in the NOW is coeval with regional records that indicate the inception of a strong and recurrent polynya from ~ 4400 yrs BP, in line with Neoglacial cooling. During warmer Holocene intervals such as the Roman Warm Period, a weaker NOW is evident, and its reduced capacity to influence bottom ocean conditions facilitated northward penetration of Atlantic Water. Future warming in the Arctic may have negative consequences for this vital biological oasis, with the potential knock-on effect of warm water penetration further north and intensified melt of the marine-terminating glaciers that flank the coast of northwest Greenland.

New determinations of tides on the north-western Ross Ice Shelf

2020 ◽  
pp. 1-14
Author(s):  
Richard D. Ray ◽  
Kristine M. Larson ◽  
Bruce J. Haines
Keyword(s):  
Time Series ◽  
Tide Gauge ◽  
High Rate ◽  
Ice Shelf ◽  
Ross Ice Shelf ◽  
The North ◽  
Global Positioning ◽  
North Western

Abstract New determinations of ocean tides are extracted from high-rate Global Positioning System (GPS) solutions at nine stations sitting on the Ross Ice Shelf. Five are multi-year time series. Three older time series are only 2–3 weeks long. These are not ideal, but they are still useful because they provide the only in situ tide observations in that sector of the ice shelf. The long tide-gauge observations from Scott Base and Cape Roberts are also reanalysed. They allow determination of some previously neglected tidal phenomena in this region, such as third-degree tides, and they provide context for analysis of the shorter datasets. The semidiurnal tides are small at all sites, yet M2 undergoes a clear seasonal cycle, which was first noted by Sir George Darwin while studying measurements from the Discovery expedition. Darwin saw a much larger modulation than we observe, and we consider possible explanations - instrumental or climatic - for this difference.

scholarly journals Disruption of the Atlantic Meridional Circulation during Deglacial Climates Inferred from Planktonic Foraminiferal Shell Weights

2021 ◽  
Vol 9 (5) ◽  
pp. 519
Author(s):  
Stergios D. Zarkogiannis
Keyword(s):  
Atlantic Ocean ◽  
Meridional Circulation ◽  
Order Approximation ◽  
Planktonic Foraminifera ◽  
Sediment Cores ◽  
Meridional Overturning Circulation ◽  
Density Structure ◽  
Last Interglacial ◽  
Shell Weight ◽  
The North

Changes in the density structure of the upper oceanic water masses are an important forcing of changes in the Atlantic Meridional Overturning Circulation (AMOC), which is believed to widely affect Earth’s climate. However, very little is known about past changes in the density structure of the Atlantic Ocean, despite being extensively studied. The physical controls on planktonic foraminifera calcification are explored here, to obtain a first-order approximation of the horizontal density gradient in the eastern Atlantic during the last 200,000 years. Published records of Globigerina bulloides shells from the North and Tropical eastern Atlantic were complemented by the analysis of a South Atlantic core. The masses of the same species shells from three different dissolution assessed sediment cores along the eastern Atlantic Ocean were converted to seawater density values using a calibration equation. Foraminifera, as planktonic organisms, are subject to the physical properties of the seawater and thus their shells are sensitive to buoyancy forcing through surface temperature and salinity perturbations. By using planktonic foraminifera shell weight as an upper ocean density proxy, two intervals of convergence of the shell masses are identified during cold intervals of the last two deglaciations that may be interpreted as weak ocean density gradients, indicating nearly or completely eliminated meridional circulation, while interhemispheric Atlantic density differences appear to alleviate with the onset of the last interglacial. The results confirm the significance of variations in the density of Atlantic surface waters for meridional circulation changes.

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