Metasomatism in the Whin Sill of the North of England. Part II: Hydrothermal Alteration by Juvenile Solutions

1929 ◽  
Vol 66 (5) ◽  
pp. 221-238 ◽  
Author(s):  
L. R. Wager
Keyword(s):  
Thin Layer ◽  
Hydrothermal Alteration ◽  
Outer Surface ◽  
Large Scale ◽  
General Character ◽  
Small Scale ◽  
Hydrothermal Solutions ◽  
Vein Quartz ◽  
Columnar Jointing ◽  
The North

In Teesdale and Weardale, at all exposures that have been examined, the Whin Sill is cut by a system of approximately vertical, sweeping, joint planes. These are distinct in general character from, and are on a larger scale than, the columnar jointing which is conspicuous in all vertical scars of Whin Sill. The pattern of the larger scale jointing on a horizontal surface varies with the depth within the sill; Fig. 1 shows diagrammatically the appearance at a depth of about 10 feet below the top of the sill; the inset Fig. 2, of the upper surface of the sill, shows how the joints have a more irregular course in the more rapidly cooled part of the dolerite. The joints do not usually pass from the dolerite into the adjacent sediment and Fig. 2 also shows a thin layer of baked sediment, attached to the outer surface of the sill, which the joint does not penetrate. The large scale jointing is often displaced by the small scale columnar jointing in a way that proves the large scale jointing to be the earlier. For the purposes of this paper, the early, large scale, joints will be referred to simply as the early joints. The walls of the early joints, for a distance of an inch or so, have been altered by hydrothermal solutions, to a rock which, although varying in composition with the distance from the joint, consists essentially of chlorite, quartz, and carbonate. The joint walls are usually about a quarter of an inch apart, and the space between them is filled with calcite and quartz. The calcite is present in greater abundance than the quartz which occurs in well shaped crystals of vein-quartz habit.

scholarly journals Internal tide energy flux over a ridge measured by a co-located ocean glider and moored ADCP

2019 ◽  
Author(s):  
Rob Hall ◽  
Barbara Berx ◽  
Gillian Damerell
Keyword(s):  
Energy Flux ◽  
Large Scale ◽  
Low Frequency ◽  
Internal Tide ◽  
Small Scale ◽  
Potential Density ◽  
The North ◽  
Model Study ◽  
Continental Shelves ◽  
Alternative Approach

Abstract. Internal tide energy flux is an important diagnostic for the study of energy pathways in the ocean, from large-scale input by the surface tide, to small-scale dissipation by turbulent mixing. Accurate calculation of energy flux requires repeated full-depth measurements of both potential density (ρ) and horizontal current velocity (u) over at least a tidal cycle and over several weeks to resolve the internal spring-neap cycle. Typically, these observations are made using full-depth oceanographic moorings that are vulnerable to being fished-out by commercial trawlers when deployed on continental shelves and slopes. Here we test an alternative approach to minimise these risks, with u measured by a low-frequency ADCP moored near the seabed and ρ measured by an autonomous ocean glider holding station by the ADCP. The method is used to measure the M2 internal tide radiating from the Wyville Thompson Ridge in the North Atlantic. The observed energy flux (4.2 ± 0.2 kW m−1) compares favourably with historic observations and a previous numerical model study. Error in the energy flux calculation due to imperfect co-location of the glider and ADCP is estimated by sub-sampling potential density in an idealised internal tide field along pseudorandomly distributed glider paths. The error is considered acceptable (

scholarly journals Characteristics of shallow thermally driven flow in the complex topography of the south-eastern Adriatic

2010 ◽  
Vol 28 (10) ◽  
pp. 1905-1922 ◽  
Author(s):  
M. T. Prtenjak ◽  
I. Tomažić ◽  
I. Kavčič ◽  
S. Đivanović
Keyword(s):  
Large Scale ◽  
Sea Breeze ◽  
Small Scale ◽  
The South ◽  
Fine Grid ◽  
Easterly Wind ◽  
Sodar Data ◽  
South Eastern ◽  
The North ◽  
Convergence Zones

Abstract. Characteristics of thermally induced flow, namely the sea breeze, are investigated along the south-eastern Adriatic. The chosen period 24–25 April 2006 favoured sea breeze development and simultaneously allowed a comparison of the large-scale wind influence (north-westerly wind versus south-easterly wind) and the complex terrain on the local circulations. Particular attention is paid to the small-scale formation of the wind field, convergence zones (CZs), channelling flows and small scale eddies, especially in the vicinity of two airports in the central part of south-eastern Adriatic. The results are based on wind measurements (from meteorological surface stations, radiosoundings, satellite data and sodar data) and further supplemented by model data at fine grid spacing. This study shows the formation of numerous irregular daytime and nighttime CZs, which occurred along the coastline in the lee of mountains and over the larger, elongated islands. The results show that the above mentioned airports are surrounded by daytime CZ formations within the lowermost 1000 m and associated updrafts of 1 m s−1, especially if CZs are maintained by the north-westerly large-scale winds. Whereas the daytime CZ was generated due to merged sea breezes, the weaker and shallower nighttime CZs were formed by wind convergence of the seaward breezes, and significantly modified by the large-scale flow of the topography (e.g., accelerated flow in the sea channels and substantial swirled flows around the islands). The passes between the coastal mountain peaks changed the inflow penetration, provoking the increase in wind speed of the channelled flow. The strongest sea breeze channelling was observed above the valley of the Neretva River, where the onshore flow reached 40 km inland with a strength of 8 m s−1, and the highly asymmetric offshore part was confined within the sea channel.

scholarly journals Importance of Resolving Kuroshio Front and Eddy Influence in Simulating the North Pacific Storm Track

2017 ◽  
Vol 30 (5) ◽  
pp. 1861-1880 ◽  
Author(s):  
Xiaohui Ma ◽  
Ping Chang ◽  
R. Saravanan ◽  
Raffaele Montuoro ◽  
Hisashi Nakamura ◽  
...  
Keyword(s):  
North Pacific ◽  
Large Scale ◽  
Climate Model ◽  
Kuroshio Extension ◽  
Storm Track ◽  
Small Scale ◽  
Low Resolution ◽  
The North ◽  
The North Pacific ◽  
Sst Anomalies

Abstract Local and remote atmospheric responses to mesoscale SST anomalies associated with the oceanic front and eddies in the Kuroshio Extension region (KER) are studied using high- (27 km) and low-resolution (162 km) regional climate model simulations in the North Pacific. In the high-resolution simulations, removal of mesoscale SST anomalies in the KER leads to not only a local reduction in cyclogenesis but also a remote large-scale equivalent barotropic response with a southward shift of the downstream storm track and jet stream in the eastern North Pacific. In the low-resolution simulations, no such significant remote response is found when mesoscale SST anomalies are removed. The difference between the high- and low-resolution model simulated atmospheric responses is attributed to the effect of mesoscale SST variability on cyclogenesis through moist baroclinic instability. It is only when the model has sufficient resolution to resolve small-scale diabatic heating that the full effect of mesoscale SST forcing on the storm track can be correctly simulated.

Interference fold patterns of the early Precambrian Rock Groups in the Songshan area, China

1982 ◽  
Vol 119 (5) ◽  
pp. 433-461 ◽  
Author(s):  
Shutian Suo ◽  
Ruqi Liu ◽  
Xingyuan Ma
Keyword(s):  
Large Scale ◽  
North China ◽  
Small Scale ◽  
Deformation History ◽  
North China Platform ◽  
Early Proterozoic ◽  
The North ◽  
Regional Deformation ◽  
History Of ◽  
Insight Into

SummaryThe Songshan area is located in the southern part of the North China platform, which is one of the most completely cratonized tectonic units of China. Its basement has experienced a complex evolutionary history and was eventually consolidated at the end of early Proterozoic time about 1.7 Ga ago.A systematic study has been made of the deformation history of the lower Proterozoic Songshan Group and the Archean Dengfeng Group. At least two widespread episodes of deformation can be recognised in the early Proterozoic Zhongyue tectonic cycle and three in the Archean Songyang cycle. Large scale and small scale interference patterns of the superimposed folding are investigated with the aim of recognizing possible regularities in their occurrence and of gaining an insight into the regional deformation history. Two important aspects of superimposition relationships are illustrated: the control of earlier structures upon later ones and the reform of the former by thelatter; their geometrical regularities are also dealt with respectively.

scholarly journals Soil cover patterns in the forest-steppe and steppe zones of the East European Plain

2019 ◽  
Vol 70 (3) ◽  
pp. 198-210
Author(s):  
Nikolay Khitrov ◽  
Maria Smirnova ◽  
Nikolai Lozbenev ◽  
Ekaterina Levchenko ◽  
Vasiliy Gribov ◽  
...  
Keyword(s):  
Large Scale ◽  
Soil Cover ◽  
Parent Material ◽  
Soil Mapping ◽  
East European Plain ◽  
Small Scale ◽  
Forest Steppe ◽  
East European ◽  
The North ◽  
Haplic Chernozems

Abstract The soil cover of the forest-steppe and steppe zones of the East European Plain is characterized by diverse soil combinations revealed during large-scale and detailed soil mapping against the background of a traditional zonal sequence of dominant automorphic soils alternating from the north to the south and clearly displayed on small-scale soil maps. The composition, configuration and functioning of particular soil cover patterns are determined by the soil forming factors acting within a given area. The elementary soil areas (detailed scale) and elementary soil cover patterns maps (large scale) of the Central Russian, Kalach, and Volga Uplands are created by both traditional and digital soil mapping methods. Low-contrasting soil combinations with the background Haplic Chernozems (Loamic or Clayic, Pachic) alternating with zooturbated Haplic Chernozems (Loamic or Clayic, Pachic) on convex elements of the microtopography and Luvic Chernozems (Loamic or Clayic, Pachic) on concave elements of the microtopography prevails under conditions of thick clay loamy parent materials and free drainage. Under conditions of shallow embedding by low-permeable clayey sediments, the soil cover includes Chernozems or Chernic Phaeozems with stagnic features in some part of the soil profile or even Mollic Stagnosols. The presence of shrink-swell clays of different ages leads to the formation of Bathyvertic Chernozems, Vertic Chernozems, Vertic Chernic Phaeozems and/or Pellic Vertisols. The presence of soluble salts in the parent material leads to the development of solonetzic soil complexes consisting of Protosodic or Sodic Chernozems and different types of Solonetzes.

scholarly journals From Ripples to Large-Scale Sand Transport: The Effects of Bedform-Related Roughness on Hydrodynamics and Sediment Transport Patterns in Delft3D

2020 ◽  
Vol 8 (11) ◽  
pp. 892
Author(s):  
Laura Brakenhoff ◽  
Reinier Schrijvershof ◽  
Jebbe van der Werf ◽  
Bart Grasmeijer ◽  
Gerben Ruessink ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Water Movement ◽  
Small Scale ◽  
Sand Transport ◽  
Influence Model ◽  
The North ◽  
Ebb Tidal Delta ◽  
Transport Patterns ◽  
Set Up

Bedform-related roughness affects both water movement and sediment transport, so it is important that it is represented correctly in numerical morphodynamic models. The main objective of the present study is to quantify for the first time the importance of ripple- and megaripple-related roughness for modelled hydrodynamics and sediment transport on the wave- and tide-dominated Ameland ebb-tidal delta in the north of the Netherlands. To do so, a sensitivity analysis was performed, in which several types of bedform-related roughness predictors were evaluated using a Delft3D model. Also, modelled ripple roughness was compared to data of ripple heights observed in a six-week field campaign on the Ameland ebb-tidal delta. The present study improves our understanding of how choices in model set-up influence model results. By comparing the results of the model scenarios, it was found that the ripple and megaripple-related roughness affect the depth-averaged current velocity, mainly over the shallow areas of the delta. The small-scale ripples are also important for the suspended load sediment transport, both indirectly through the affected flow and directly. While the current magnitude changes by 10–20% through changes in bedform roughness, the sediment transport magnitude changes by more than 100%.

scholarly journals The Production and Dissipation of Compensated Thermohaline Variance by Mesoscale Stirring

2009 ◽  
Vol 39 (10) ◽  
pp. 2477-2501 ◽  
Author(s):  
K. Shafer Smith ◽  
Raffaele Ferrari
Keyword(s):  
Large Scale ◽  
Vertical Mixing ◽  
Small Scale ◽  
Vertical Diffusion ◽  
The North ◽  
Salinity Gradients ◽  
Scale Temperature ◽  
The Mean ◽  
Geostrophic Turbulence ◽  
Quasigeostrophic Model

Abstract Temperature–salinity profiles from the region studied in the North Atlantic Tracer Release Experiment (NATRE) show large isopycnal excursions at depths just below the thermocline. It is proposed here that these thermohaline filaments result from the mesoscale stirring of large-scale temperature and salinity gradients by geostrophic turbulence, resulting in a direct cascade of thermohaline variance to small scales. This hypothesis is investigated as follows: Measurements from NATRE are used to generate mean temperature, salinity, and shear profiles. The mean stratification and shear are used as the background state in a high-resolution horizontally homogeneous quasigeostrophic model. The mean state is baroclinically unstable, and the model produces a vigorous eddy field. Temperature and salinity are stirred laterally in each density layer by the geostrophic velocity and vertical advection is by the ageostrophic velocity. The simulated temperature–salinity diagram exhibits fluctuations at depths just below the thermocline of similar magnitude to those found in the NATRE data. It is shown that vertical diffusion is sufficient to absorb the laterally driven cascade of tracer variance through an amplification of filamentary slopes by small-scale shear. These results suggest that there is a strong coupling between vertical mixing and horizontal stirring in the ocean at scales below the deformation radius.

The effects of grazing on spider assemblages in upland heather moorland

2005 ◽  
Vol 2005 ◽  
pp. 65-65
Author(s):  
L. Paterson ◽  
R. A. Sanderson ◽  
S. P. Rushton
Keyword(s):  
Large Scale ◽  
Management Practices ◽  
Prey Type ◽  
Small Scale ◽  
Vegetation Density ◽  
Important Indicator ◽  
The North ◽  
Hunting Strategies ◽  
Web Structure ◽  
Reptile Species

Invertebrates are of particular interest on heather moorlands because of their rapid response to small scale habitat changes. Spiders constitute a variable proportion of the diet of heather moorland bird, mammal and reptile species. Furthermore, spiders may be an important indicator of habitat change resulting from management practices, especially those that exert a large- scale spatial impact, e.g. grazing. The component families and species of spider assemblages indicate, through their differing preference for web attachments and web structure, the vegetation density, height and structure (Marc et al., 1999). This effect may be especially pronounced where continued grazing at a particular stocking rate results in characteristic patterns in the vegetation structure. Species and family specific hunting strategies determine prey type and so the presence of some spider species may indicate the presence of a preferred prey species. This study aims to investigate the effect of grazing with sheep alone or in combination with cattle grazing on an upland heather moorland in the north of England.

scholarly journals Small-scale spatial structuring of burrowed sandeels and the catching properties of the dredge

2013 ◽  
Vol 70 (2) ◽  
pp. 379-386 ◽  
Author(s):  
Espen Johnsen ◽  
Alf Harbitz
Keyword(s):  
Large Scale ◽  
Spatial Models ◽  
Small Scale ◽  
The North ◽  
Gamma Distributions ◽  
Abundance Estimates ◽  
Efficient Sampling ◽  
Spatial Structuring ◽  
The North Sea ◽  
Catch Rates

Abstract Johnsen, E., and Harbitz, A. 2013. Small-scale spatial structuring of burrowed sandeels and the catching properties of the dredge – ICES Journal of Marine Science, 70: 379–386. The lesser sandeel (Ammodytes marinus) remains burrowed for long periods in the seabed in sandy areas, and its habitat preference is reflected in a large-scale (10 km) patchy distribution in the North Sea. The small-scale spatial structure of sandeels in the seabed is less known. In this study, it was found that sandeel catches in grabs and dredges fit gamma distributions with a common shape parameter on both a 10 m and a 100 m scale. These spatial models were used to examine the catching properties of the dredge, which, in the new ICES sandeel assessment, is used to estimate recruitment and maturity curves. Analyses of the empirical data and simulations of the dredge and grab catch rates show very low dredge catchability (∼5%), but no length-dependent catchability in the dredge was found. However, analyses of the catch rates of parallel dredge hauls indicated increasing dredge catchability with sandeel density. The observed small-scale patchiness and the low and seemingly density-dependent dredge catchability result in biased abundance estimates with low precision. Therefore, we recommend a joint international effort to develop a more catch-efficient sampling dredge, where the effect of density on catchability is further examined.

scholarly journals Finescale Structure of the T–S Relation in the Eastern North Atlantic

2005 ◽  
Vol 35 (8) ◽  
pp. 1437-1454 ◽  
Author(s):  
R. Ferrari ◽  
K. L. Polzin
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Salinity Gradient ◽  
Mesoscale Eddies ◽  
Thermal Dissipation ◽  
Small Scale ◽  
The North ◽  
Wide Range ◽  
Using Data ◽  
Gyre Circulation

Abstract Distributions of temperature (T) and salinity (S) and their relationship in the oceans are the result of a balance between T–S variability generated at the surface by air–sea fluxes and its removal by molecular dissipation. In this paper the role of different motions in setting the cascade of T–S variance to dissipation scales is quantified using data from the North Atlantic Tracer Release Experiment (NATRE). The NATRE observational programs include fine- and microscale measurements and provide a snapshot of T–S variability across a wide range of scales from basin to molecular. It is found that microscale turbulence controls the rate of thermal dissipation in the thermocline. At this level the T–S relation is established through a balance between large-scale advection by the gyre circulation and small-scale turbulence. Further down, at the level of intermediate and Mediterranean waters, mesoscale eddies are the rate-controlling process. The transition between the two regimes is related to the presence of a strong salinity gradient along density surfaces associated with the outflow of Mediterranean waters. Mesoscale eddies stir this gradient and produce a rich filamentation and salinity-compensated temperature inversions: isopycnal stirring and diapycnal mixing are both required to explain the T–S relation at depth.

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