共查询到20条相似文献，搜索用时 31 毫秒
1.
Dynamics of plankton growth in the Barents Sea: model studies 总被引：2，自引：0，他引：2
1-D and 3-D models of plankton production in the Barents Sea are described and a few simulations presented. The 1-D model has two compartments for phytoplankton (diatoms and P. pouchelii) , three for limiting nutrients (nitrate, ammonia and silicic acid), and one compartment called "sinking phytoplankton". This model is coupled to a submodel of the important herbivores in the area and calculates the vertical distribution in a water column. Simulations with the 3-D model indicate a total annual primary production of 90-120g C m−2 yr−1 in Atlantic Water and 20-50g C m−2 yr−1 in Arctic Water, depending on the persistence of the ice cover during the summer.
The 3-D model takes current velocities, vertical mixing, ice cover, and temperature from a 3-D hydrodynamical model. Input data are atmospheric wind, solar radiation, and sensible as well as latent heat flux for the year 1983. The model produces a dynamic picture of the spatial distribution of phytoplankton throughout the spring and summer. Integrated primary production from March to July indicates that the most productive area is Spitsbcrgenbanken and the western entrance to the Barents Sea. i.e. on the northern slope of Tromsøflaket. 相似文献
The 3-D model takes current velocities, vertical mixing, ice cover, and temperature from a 3-D hydrodynamical model. Input data are atmospheric wind, solar radiation, and sensible as well as latent heat flux for the year 1983. The model produces a dynamic picture of the spatial distribution of phytoplankton throughout the spring and summer. Integrated primary production from March to July indicates that the most productive area is Spitsbcrgenbanken and the western entrance to the Barents Sea. i.e. on the northern slope of Tromsøflaket. 相似文献
2.
Uptake rates of NH4 + , NO3 − and dissolved organic nitrogen (urea) were measured in phytoplankton and in ice algae in the Barents Sea using a 15 N-technique. NO3 − was the most important nitrogen source for the ice algae (f-ratio = 0.92). The in situ irradiances in the subsurface chlorophyll maximum and in the ice algal communities were low. The in situ NO3 − uptake rate in the ice algal communities was light-limited The in situ NO3 − and NH4 − uptake rates in the subsurface chlorophyll maximum were at times light-limited. It is hypothesised that NH4 + may accumulate in low light in the bottom of the euphotic zone and inhibit the in situ NO3 − uptake rate. 相似文献
3.
Andrey Sazhin 《Polar research》2004,23(1):11-18
Autotrophic and heterotrophic flagellates, microalgae and ciliates sampled at four stations in the White Sea in April 2002 were studied using epifluorescence microscopy. The concentrations of phototrophic 1.5 μm algae in the middle and lower part of the ice core were very high: up to 6.1 ± 108 cells I−1 and 194 μg C I−1 . Heterotrophic algae made up the largest proportion of the nanoplankton (2-20 μm) and microplankton (20-200 μm) at depths 10-25 m below the ice. The proportion of ciliates ranged from about 0.01% to 18% at different stations and depths. Most of the ciliate biomass in the ice was made up of typical littoral zone species, whereas the water under the ice was dominated by phototrophic Myrionecta rubra . Ice algae, mainly flagellates in the upper ice layer and diatoms in the bottom ice layer, supported the proliferation of heterotrophs, algae and ciliates in early spring. Small heterotrophs and diatoms from the ice may provide food for early growth and development of pelagic copepods. Mass development of the ice algae in early spring appears typical for the seasonal ice of the White Sea. Ice algae differ in species composition from the spring pelagic community and develop independently in time and space from the spring phytoplankton bloom. 相似文献
4.
The colonial algae Phaeocystis pouchetii and Dinobryon pellucidum dominated the phytoplankton crop at three stations in the Polar Front area of the Barents Sea.
Lipid extracted from the seawater containing the phytoplankton was dominated by neutral lipid classes, particularly triacylglycerols, and phospholipids were more abundant than galactolipids at all stations. Polyunsaturated fatty acids comprised between 15 and 26% of fatty acids of total lipid.
Of the carbon assimilated into lipid over 24 hours, 40% was located in the neutral lipid fraction. Phospholipids contained a smaller proportion of fixed carbon than galactolipids.
No defiinte relationships were observed between the distribution of fixed carbon in photosynthetic end products and the temperature or irradiance at which the phytoplankton was incubated. At a constant irradiance of 8.5 μmol m−2 s−1 , the highest proportion of fixed carbon was recovered in protein at 4.5°C, but at −1.5°C most radioactivity was present in low molecular weight compounds. Regardless of incubation conditions, lipid always contained less than 30% of total assimilated carbon. 相似文献
Lipid extracted from the seawater containing the phytoplankton was dominated by neutral lipid classes, particularly triacylglycerols, and phospholipids were more abundant than galactolipids at all stations. Polyunsaturated fatty acids comprised between 15 and 26% of fatty acids of total lipid.
Of the carbon assimilated into lipid over 24 hours, 40% was located in the neutral lipid fraction. Phospholipids contained a smaller proportion of fixed carbon than galactolipids.
No defiinte relationships were observed between the distribution of fixed carbon in photosynthetic end products and the temperature or irradiance at which the phytoplankton was incubated. At a constant irradiance of 8.5 μmol m
5.
Hydrographic and current measurements obtained during the Norwegian Antarctic Research Expedition 1978/79 to the southern Weddell Sea are presented. Cold, dense Ice Shelf Water circulating under the floating ice shelves is observed to leave the shelf as a concentrated bottom flow. From moored current metres this discharge is estimated at 0.7 106 m3 /s at -2.0°C (one year average) and with no appreciable seasonal variation. This contribution to the Weddell Sea Bottom Water is clearly identified through extreme temperature gradients at our deepest stations (below 2500 m). The core of Weddell Deep Water shows a considerable (T ∼ 0.5°C) warming up since 1977, presumably due to the lack of polynya activity in the intervening period. Measurements in the coastal current at the ice shelf (70°S, 2°W) show step structures which are probably due to cooling and melting at the vertical ice barrier. Slight supercooling due to circulation under the ice shelf is also seen. The net effect of the ice shelf boundary seems to be a deep reaching cooling and freshening of the coastal current providing the low salinity, freezing point Eastern Shelf Water. This process is considered a preconditioning which enhances production of the saline Western Shelf Water which in turn is transformed to Ice Shelf Water. 相似文献
6.
North Atlantic Water (NAW) is an important source of heat and salt to the Nordic seas and the Arctic Ocean. To measure the transport and variability of one branch of NAW entering the Arctic, a transect across the entrance to the Barents Sea was occupied 13 times between July 1997 and November 1999, and hydrography and currents were measured. There is large variability between the cruises, but the mean currents and the hydrography show that the main inflow takes place in Bjørnøyrenna, with a transport of 1.6 Sv of NAW into the Barents Sea. Combining the flow field with measurements of temperature and salinity, this results in mean heat and salt transports by NAW into the Barents Sea of 3.9×1013 W and 5.7×107 kg s−1 , respectively. The NAW core increased in temperature and salinity by 0.7 °C yr−1 and 0.04 yr−1 , respectively, over the observation period. Variations in the transports of heat and salt are, however, dominated by the flow field, which did not exhibit a significant change. 相似文献
7.
Volume, heat and salt transport by the West Spitsbergen Current 总被引：1，自引：0，他引：1
During the summer of 2000 (June-July) 14 CTD and ADCP transects perpendicular to the West Spitsbergen Current and along the western border of the Barents Sea were made. The measurements covered the area between 69° 43'and 80° N and 01° and 20° E. The main purpose was to follow changes in volume, heat and salt content of Atlantic Water (AW) on its way north. The strongest and most stable flow of AW was located along the continental slope where northward flowing currents exceeding 40 cm/sec were measured. A few weaker northward branches were also found to the west of the slope. South-directed currents were recorded between them and eddy-like mesoscale structures were commonly observed. Measured by vessel-mounted acoustic Doppler current profiler (VM-ADCP), the net northward transport of AW volume in the upper 136 m layer decreased from nearly 6 Sv at the southernmost transect to below 1 Sv at a latitude of 78° 50'N. Similarly, heat transport drops from about 173 TW to about 9 TW and relative salt transport (over 34.92 psu) from 980 × 103 kg/sec to 14 × 103 kg/sec. Transport in the southern direction prevails at the transect located between 79° 07'and 79° 30'N. The calculated baroclinic geostrophic transport of AW volume, heat and salt in the upper 1000 m layer behaves similarly. East-directed transport dominates at the Barents Sea boundary while westward flow prevails on the western side of the West Spitsbergen Current. 相似文献
8.
Anthony Arendt 《Geografiska Annaler: Series A, Physical Geography》1999,81(4):477-487
Broadband surface albedo measurements, made during the summer melt season at three weather stations on John Evans Glacier (79°40 ' N, 74°00 ' W), varied strongly with the solar zenith angle ( θ z ). Tests were carried out to assess the impact of diurnal variations in surface albedo on seasonal net shortwave radiation ( K * ) totals. Removing the diurnal signal from albedo measurements by daily averaging of hourly measurements, or by applying midday measurements to all hours of the day, changed K * by up to 16%. Ignoring measurements made at θ z & 75°, to account for measurement (cosine) error at high θ z , decreased K * by between 5 and 18%. Given the sensitivity of K * to diurnal patterns in surface albedo, experiments were carried out with two albedo models. One model accounted for albedo variations with θ z and one did not. The model driven by θ z , when implemented within a surface energy balance model for John Evans Glacier, produced better melt estimates. This suggests that diurnal variations in surface albedo should be accounted for in energy balance models of glacier melt. 相似文献
9.
In Paper I (Breuer & Wolf 1995), a preliminary interpretation of the postglacial land emergence observed at a restricted set of six locations in the Svalbard Archipelago was given. The study was based on a simple model of the Barents Sea ice sheet and suggested increases in lithosphere thickness and asthenosphere viscosity with increasing distance from the continental margin.
In the present paper, the newly developed high-resolution load model. BARENTS-2, and land-uplift observations from an extended set of 25 locations are used to study further the possibility of resolving lateral heterogeneity in the upper mantle below the northern Barents Sea. A comparison of the calculated and observed uplift values shows that the lithosphere thickness is not well resolved by the observations, although values above 110 km are most common for this parameter. In contrast to this, there are indications of a lateral variation of asthenosphere viscosity. Whereas values in the range 1018 -1020 Pas are inferred for locations close to the continental margin, 1020 -1021 Pa s are suggested further away from the margin.
A study of the sensitivity of the values found for lithosphere thickness and asthenosphere viscosity to modifications of load model BARENTS-2 shows that such modifications can be largely accommodated by appropriate changes in lithosphere thickness, whereas the suggested lateral variation of asthenosphere viscosity is essentially unaffected. An estimate of the influence of the Fennoscandian. ice sheet leads to the conclusion that its neglect results in an underestimation of the thickness of the Barents Sea ice sheet by about 10 per cent. 相似文献
In the present paper, the newly developed high-resolution load model. BARENTS-2, and land-uplift observations from an extended set of 25 locations are used to study further the possibility of resolving lateral heterogeneity in the upper mantle below the northern Barents Sea. A comparison of the calculated and observed uplift values shows that the lithosphere thickness is not well resolved by the observations, although values above 110 km are most common for this parameter. In contrast to this, there are indications of a lateral variation of asthenosphere viscosity. Whereas values in the range 10
A study of the sensitivity of the values found for lithosphere thickness and asthenosphere viscosity to modifications of load model BARENTS-2 shows that such modifications can be largely accommodated by appropriate changes in lithosphere thickness, whereas the suggested lateral variation of asthenosphere viscosity is essentially unaffected. An estimate of the influence of the Fennoscandian. ice sheet leads to the conclusion that its neglect results in an underestimation of the thickness of the Barents Sea ice sheet by about 10 per cent. 相似文献
10.
Micromonas pusilla (Butcher) Manton & Parke appears to be a prominent member of the Barents Sea picoplankton community as revealed by the serial dilution culture method. Cell numbers frequently exceeded 107 cells 1−1 , though they usually varied between 103 and 106 cells l−1 . A number of other identified and unidentified taxa were recorded and quantified. Distribution relative to the marginal ice zone is reported. 相似文献
11.
Distribution and life history of krill from the Barents Sea 总被引：2，自引：0，他引：2
Krill from the Barents Sea were studied on six cruises from 1985 to 1989. Thysanoessa inermis and T. longicaudata were the dominant species, while T. raschii and Meganyctiphanes norvegica were rarer in the studied areas. The two dominant species T. inermis and T. longicaudata are mainly found in the Atlantic. Water and they do not to a large extent penetrate into Arctic water masses in the northern Barents Sea. M. norvegica is a more strict boreal species that does not occur as extensively in the Barents Sea as do the Thysanoessa species. The mean population abundance ranged from 1 to 61 individuals m−2 for T. inermis and from 2 to 52 ind. M−2 for T. longicaudata . The mean dry weight biomass of these two species ranged from 14 to 616 and from 19 to 105 mg−2 . Length frequency distributions indicate a life span of just over two years for T. inermis and T. longicaudata . Growth took place from about April to autumn with no apparent growth during winter. Maturation and spawning seem to occur after two years for T. inermis and one year for T. longicaudata . Main spawning occurred from May to June coinciding with the spring phytoplankton bloom. Captive spawners of T. inermis (total length 17-22 mm) shed 30-110 eggs per female in a single batch. 相似文献
12.
MARIA VERNET 《Polar research》1991,10(1):129-146
Pigment budgets use chlorophyll a and phaeopigment standing stock in combination with their photo-oxidation and sedimentation rates in the euphotic zone to estimate phytoplankton growth and grazing by micro- and macrozooplankton. Using this approach, average phytoplankton growth in the euphotic zone of the Barents Sea was estimated at 0.17 and 0.14 d−1 during spring of 1987 and 0.018 and 0.036 d−1 during late- and postbloom conditions in summer of 1988. Spring growth was 65% lower than the estimates from radiocarbon incorporation, supporting a 33% pigment loss during grazing. Macrozooplankton grazing and cell sinking were the main loss terms for phytoplankton during spring while microzooplankton grazing was dominant in summer.
In contrast to tropical and temperate waters, Arctic waters are characterized by a high phaeopigment: chlorophyll a ratio in the seston. Photooxidation rates of phaeopigments at in situ temperatures (0 ± 1°C) are lower than in temperate waters and vary by a factor of 2 for individual forms (0.009 to 0.018 m−2 mol−1 ). The phaeopigment fraction in both the suspended and sedimenting material was composed of seven main compounds that were isolated using high-performance liquid chromatography and characterized by spectral analysis. The most abundant phaeopigment in the sediment traps, a phaeo-phorbide-like molecule of intermediate polarity (phaeophorbide a3 ), peaked in abundance in the water column below the 1% isolume for PAR (60-80 m) and showed the highest rate of photooxidation. This phaeopigment was least abundant in the seston when phytoplankton was dominated by prymnesiophytcs but increased its abundance in plankton dominated by diatoms. This distribution suggests that larger grazers feeding on diatoms are the main producers of this phaeopigment. 相似文献
In contrast to tropical and temperate waters, Arctic waters are characterized by a high phaeopigment: chlorophyll a ratio in the seston. Photooxidation rates of phaeopigments at in situ temperatures (0 ± 1°C) are lower than in temperate waters and vary by a factor of 2 for individual forms (0.009 to 0.018 m
13.
H. Motoyama K. Kamiyama M. Igarashi F. Nishio & O. Watanabe 《Geografiska Annaler: Series A, Physical Geography》2000,82(1):33-38
10 m and 2.3 m ice cores were obtained on Austre Brøggerbreen, Spitsbergen in Svalbard (78°53 ' N, 11°56 ' E, 450 m a.s.l.) in September 1994 and in March 1995, respectively. Stratigraphy, bulk density, pH, electrical conductivity, and major ions were obtained from the core samples.
The chemical effect of meltwater percolation through snow/ice is examined. Good correlation between Cl− and Na+ was obtained. The ratio of Cl− to Na+ was 1.14 which was nearly the same value as in bulk sea water. However, the variation of Cl− /Na+ shows that higher ratio occured in the bubble-free ice. Furthermore the Cl− ions remain in higher concentration than SO 4 2− or Na+ ions. 相似文献
The chemical effect of meltwater percolation through snow/ice is examined. Good correlation between Cl
14.
Aerial strip surveys of polar bears in the Barents Sea 总被引：1，自引：0，他引：1
Aerial strip surveys of polar bears in the Barents Sea were performed by helicopter in winter 1987. The number of bears within 100 m on each side of the helicopter was counted. A total of 263.6 km2 was surveyed and 21 bears were counted. Most of the bears were found in the southern part of the area, which indicates that the southwestern ice edge area in the Barents Sea is a very important winter habitat for polar bears. 相似文献
15.
A coupled ice-ocean ecosystem model for 1-D and 3-D applications in the Bering and Chukchi Seas 
下载免费PDF全文
下载免费PDF全文 Clara Deal 《极地研究》2008,19(2):218-229
Primary production in the Bering and Chukchi Seas is strongly influenced by the annual cycle of sea ice.Here pelagic and sea ice algal ecosystems coexist and interact with each other.Ecosystem modeling of sea ice associated phytoplankton blooms has been understudied compared to open water ecosystem model applications. This study introduces a general coupled ice-ocean ecosystem model with equations and parameters for 1-D and 3-D applications that is based on 1-D coupled ice-ocean ecosystem model development in the landfast ice in the Chukchi Sea and marginal ice zone of Bering Sea.The biological model includes both pelagic and sea ice algal habitats with 10 compartments:three phytoplankton(pelagic diatom,flagellates and ice algae:D,F,and Ai),three zooplankton(copepods,large zooplankton,and micro-zooplankton :ZS,ZL,ZP),three nutrients(nitrate+nitrite,ammonium,silicon: NO_3,NH_4,Si) and detritus(Det).The coupling of the biological models with physical ocean models is straightforward with just the addition of the advection and diffusion terms to the ecosystem model.The coupling with a multi-category sea ice model requires the same calculation of the sea ice ecosystem model in each ice thickness category and the redistribution between categories caused by both dynamic and thermodynamic forcing as in the physical model.Phytoplankton and ice algal self-shading effect is the sole feedback from the ecosystem model to the physical model. 相似文献
16.
使用2003—2014年6—9月份的AMSR-E和AMSR-2海冰密集度数据计算了北极海冰范围, 并获得海冰空间分布图。通过分析得出, 2014年北极夏季海冰范围在数值上与2003—2013年的多年平均值很接近, 在空间分布上与多年中值范围相比主要表现为两个方面的不同：(1)2014年夏季拉普捷夫海及其以北海域海冰明显少于多年中值范围, 9月份冰区最北边界超过了85°N;(2)巴伦支海北部斯瓦尔巴群岛至法兰士约瑟夫地群岛区域海冰范围明显多于多年中值范围, 而且海冰范围在8月份不减反增, 冰区边界较7月份往南扩张了约0.8个纬度。2014年夏季在拉普捷夫海以南风为主, 而在巴伦支海以北风为主。南风将俄罗斯大陆上温暖的空气吹向高纬地区, 造成高纬地区温度偏高, 促进拉普捷夫海海冰融化, 并使海冰往北退缩。北风将北冰洋上的冷空气吹向低纬地区, 造成巴伦支海的气温偏低, 不利于海冰的融化, 同时北风使海冰往南漂移扩散, 造成巴伦支海北部海冰范围在2014年偏多。2014年北地群岛航线开通时间范围大约在8月上旬到10月上旬, 时长约两个月。新西伯利亚群岛及附近海域的开通时间稍早于北地群岛, 但关闭时间比北地群岛晚, 所以 2014年东北航道全线开通的时间主要受制于北地群岛附近海冰变化。 相似文献
17.
The sympagic fauna (= ice fauna) of the Barents Sea was investigated on nine different cruises in 1982-1988. Each cruise lasted from two to five weeks. Sampling techniques were based on scuba diving. The abundant sympagic organisms were the polar cod ( Boreogadus saida ) and the three amphipods Apherusa glacialis, Onisimus sp. and Gammarus wilkitzkii .
Mean biomass-values (wet weight) of the invertebrate sympagic fauna ranged from 0 to 2 g/m2 . Values above 0.001 g/m2 were not recorded in five of the nine cruises. This is orders of magnitude lower than mean values recorded in multi-year ice north of Svalbard and in the Fram Strait where values between 1-10g/m2 are quite common.
Apherusa glacialis seemed to have the best spreading capacity of the three most conspicuous amphipods. Gammarus wilkitzkii was most dependent on a passive transport with the ice.
Sympagic amphipods play an important part in a food chain from microalgae to polar cod and marine birds in areas covered with ice, especially in areas with multi-year ice. 相似文献
Mean biomass-values (wet weight) of the invertebrate sympagic fauna ranged from 0 to 2 g/m
Apherusa glacialis seemed to have the best spreading capacity of the three most conspicuous amphipods. Gammarus wilkitzkii was most dependent on a passive transport with the ice.
Sympagic amphipods play an important part in a food chain from microalgae to polar cod and marine birds in areas covered with ice, especially in areas with multi-year ice. 相似文献
18.
Meridional zonation of the Barents Sea ecosystem inferred from satellite remote sensing and in situ bio-optical observations 总被引：2，自引：0，他引：2
B. GREG MITCHELL ERIC A. BRODY EUENG-NAN YEH CHARLES MCCLAIN JOSEFINO COMISO NANCY G. MAYNARD 《Polar research》1991,10(1):147-162
The Barents Sea is a productive, shallow, high-latitude marine ecosystem with complex hydrographic conditions. Zonal hydrographic bands defined by a coastal current. North Atlantic Water, the Polar Front, and the seasonally variable marginal ice edge zone create a meridional zonation of the ecosystem during the spring-summer transition. The features reveal themselves in satellite imagery and by high-resolution (vertical and horizontal) physical-optical-biological sampling.
Surprisingly, the long-term (7-year) mean of Coastal Zone Color Scanner (CZCS) imagery reveals the Barents Sea as an anomalous "blue-water" regime at high latitudes that are otherwise dominated by satellite-observed surface blooms. A combination of satellite imagery and in situ bio-optical analyses indicate that this pattern is caused by strong stratification in summer with surface nutrient depletion. The onset of stratification of the entire region is linked to the extent of the winter ice edge: cold years with extensive sea ice apparently stratify early due to ice melt; warm years stratify later, perhaps due to weaker thermal stratification of the Atlantic waters (e.g. Skjoldal et al. 1987). The apparent "low chlorophyll" indicated by the CZCS 7-year mean is partly due to sampling error whereby the mean is dominated by images taken later in the summer. In fact, massive blooms of subsurface phytoplankton embedded in the pycnocline persist throughout the summer and maintain substantial rates of primary production. Further, these subsurface blooms that are not observed by satellite are responsible for dramatic gradients in the beam (c1 ) and spectral diffuse (k) attenuation coefficients. The Barents Sea exemplifies the need to couple satellite observations with spatially and temporally resolved biogeographic ecosystem models in order to estimate the integrated water column primary production, mass flux or spectral light attenuation coefficients. 相似文献
Surprisingly, the long-term (7-year) mean of Coastal Zone Color Scanner (CZCS) imagery reveals the Barents Sea as an anomalous "blue-water" regime at high latitudes that are otherwise dominated by satellite-observed surface blooms. A combination of satellite imagery and in situ bio-optical analyses indicate that this pattern is caused by strong stratification in summer with surface nutrient depletion. The onset of stratification of the entire region is linked to the extent of the winter ice edge: cold years with extensive sea ice apparently stratify early due to ice melt; warm years stratify later, perhaps due to weaker thermal stratification of the Atlantic waters (e.g. Skjoldal et al. 1987). The apparent "low chlorophyll" indicated by the CZCS 7-year mean is partly due to sampling error whereby the mean is dominated by images taken later in the summer. In fact, massive blooms of subsurface phytoplankton embedded in the pycnocline persist throughout the summer and maintain substantial rates of primary production. Further, these subsurface blooms that are not observed by satellite are responsible for dramatic gradients in the beam (c
19.
20.
Summary. The deep structure of the Faeroe–Shetland Channel has been investigated as part of the North Atlantic Seismic Project. Shot lines were fired along and across the axis of the Channel, with recording stations both at sea and on adjacent land areas. At 61°N, 1.7 km of Tertiary sediments overlies a 3.9–4.5 km s-1 basement interpreted as the top of early Tertiary volcanics. A main 6.0–6.6 km s-1 crustal refractor interpreted as old oceanic crust occurs at about 9 km depth. The Moho (8.0 ° 0.2 km s-1 ) is at about 15–17 km depth. There is evidence that P n may be anisotropic beneath the Faeroe–Shetland Channel. Arrivals recorded at land stations show characteristics best explained by scattering at an intervening boundary which may be the continent–ocean crustal contact or the edge of the volcanics.
The Moho delay times at the shot points, determined by time-term analysis, show considerable variation along the axis of the Channel. They correlate with the basement topography, and the greatest delays occur over the buried extension of the Faeroe Ridge at about 60° 15'N, where they are nearly 1 s more than the delays at 61°N after correction for the sediments. The large delays are attributed to thickening of the early Tertiary volcanic layer with isostatic downsagging of the underlying crust and uppermost mantle in response to the load, rather than to thickening of the main crustal ayer.
The new evidence is consistent with deeply buried oceanic crust beneath the Faeroe–Shetland Channel, forming a northern extension of Rockall Trough. The seabed morphology has been grossly modified by the thick and laterally variable pile of early Tertiary volcanic rocks which swamped the region, accounting for the anomalous shallow bathymetry, the transverse ridges and the present narrowness of the Channel. 相似文献
The Moho delay times at the shot points, determined by time-term analysis, show considerable variation along the axis of the Channel. They correlate with the basement topography, and the greatest delays occur over the buried extension of the Faeroe Ridge at about 60° 15'N, where they are nearly 1 s more than the delays at 61°N after correction for the sediments. The large delays are attributed to thickening of the early Tertiary volcanic layer with isostatic downsagging of the underlying crust and uppermost mantle in response to the load, rather than to thickening of the main crustal ayer.
The new evidence is consistent with deeply buried oceanic crust beneath the Faeroe–Shetland Channel, forming a northern extension of Rockall Trough. The seabed morphology has been grossly modified by the thick and laterally variable pile of early Tertiary volcanic rocks which swamped the region, accounting for the anomalous shallow bathymetry, the transverse ridges and the present narrowness of the Channel. 相似文献