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1.
Tectonic framework of the eastern Alboran and western Algerian Basins,western Mediterranean 总被引：2，自引：2，他引：0
Recent progress in the knowledge of the Alboran region subaerial geology and the results of the Garcia del Cid seismic cruises stimulate a reexamination of the tectonic framework of the southwestern part of the Mediterranean. The subaerial geology is governed by a north-south stress field, whereas the marine structures indicate an east-west stress regime. This apparent contradiction results from a difference in age of the tectonics. The main marine extensional features are related to the opening of basins toward the southwest during Burdigalian-Langhian times, while the subaerial structures were developed during a compressional regime from the Tortonian period up to the present. 相似文献
2.
《Deep Sea Research Part I: Oceanographic Research Papers》2006,53(6):942-959
Five moorings ML1–ML5 were deployed on the slope of the Solomon Rise in the Melanesian Basin in the western North Pacific, northeastward at increasing water depths. We measured the velocities of the western branch current of the deep western boundary current (DWBC) and the upper deep current carrying the Lower and Upper Circumpolar Waters (LCPW, UCPW), respectively. The daily mean velocity data from 1–3 February 1999 to 24–26 February 2000 were analyzed, and variability of the DWBCs was clarified. Although the current meters did not entirely cover the western branch current of the DWBC composed of two or three streams, a stream of the western branch current was observed at a depth of 4700 m at ML4 or 4260 m at ML5 for more than half of the observation period. The stream had a mean velocity of 3.7 cm s−1 and alternated between ML4 and ML5 at 20- to 40-day intervals without occupying both of ML4 and ML5 simultaneously. This shows that the width of the stream is less than 120 km (distance between ML4 and ML5), and the position changes in a similar range. In contrast to the velocity of the eastern branch current of the DWBC, that of the western branch current did not decrease with decreasing depths to 4000 m. This reflects the vertical division into the branch currents by the bifurcation of the DWBC. The western branch current of the DWBC is located at the deep side of the countercurrent which was almost always observed at depths of 3880 and 4080 m at ML3. The countercurrent was thought to be the return flow of the western branch current that is partly reversed in the East Mariana Basin. The previous estimate of geostrophic transport of LCPW at the time of the mooring deployment was corrected to 1.4 Sv (106 m3 s−1) in the western branch current, 1.7 Sv in the countercurrent, and 1.1 Sv in the inflow to the East Caroline Basin. The upper deep current was located over the slope of the Solomon Rise with water depth less than 4500 m including ML1–ML3. It flowed at depths of approximately 2000–3500 m with the highest velocity in the middle of this layer and seldom reached the near-bottom where eddy-like disturbances existed. Its volume transport at the mooring deployment was 10.4 Sv. The upper deep current during the first half of the observation period had double cores divided by the countercurrent at ML1, whereas that during the second half had a single core, as the countercurrent at ML1 disappeared in early September 1999. The vector mean velocities of the upper deep current were 5.0 (2650 m, ML2) and 3.6 cm s−1 (1880 m, ML3) during the first half of the observation period and 7.0 cm s−1 (2670 m, ML1) during the second half; they ranged from 3 to 7 cm s−1. Similarly, those of the countercurrent at ML1 during the first half were 6.4, 3.8, 4.6 cm s−1 (2170, 2670, 3570 m). 相似文献
3.
Evolution of the western Barents Sea 总被引：2，自引：0，他引：2
Jan Inge Faleide Steinar T. Gudlaugsson Gerard Jacquart 《Marine and Petroleum Geology》1984,1(2):123-150
Information from multichannel seismic reflection data complemented by seismic refraction, gravity and magnetics forms the basis for a regional structural and evolutionary model of the western Barents Sea during post-Caledonian times. The western Barents Sea contains a thick succession, locally > 10 km, of Upper Paleozoic to Cenozoic sedimentary rocks covering a basement of probably Caledonian origin. The area is divided into three regional geological provinces: (1) an east-west trending basinal province between 74°N and the coast of Norway; (2) an elevated platform area to the north towards Svalbard; and (3) the western continental margin. Several structural elements of different origin and age have been mapped within each of these provinces. The main stratigraphic sequence boundaries have been tentatively dated from available well information, correlation with the geology of adjacent areas, and correlation with the interregional unconformities caused by relative changes of sea level. The main structural elements were developed during three major post-Caledonian tectonic phases: the Svalbardian phase in Late Devonian to Early Carboniferous times, the Mid and Late Kimmerian phase in Mid Jurassic to Early Cretaceous times and Cenozoic tectonism related to the progressive northward opening of the Norwegian-Greenland Sea. The sediments are predicted to be of mainly clastic origin except for a thick sequence of Middle Carboniferous — Lower Permian carbonates and evaporites. Salt diapirs have developed in several sub-basins, especially in the Nordkapp Basin where they form continuous salt walls that have pierced through > 7 km of sediments. 相似文献
4.
厦门西海域浮游植物的生态 总被引：7，自引：5，他引：7
本文分析、鉴定了于1989年4月至1990年3月,逐月采自厦门西海域的7个站位的112份样品。结果表明,本海区浮游植物共129种,其中蓝藻1种,硅藻105种,金藻1种,甲藻22种。按其分布特点,可分为两大生态类群:广布种占57%,暖水种占43%。浮游植物细胞总量的季节分布是8月出现主高峰,5月为次高峰,3月是最低谷期。此外,对其数量分布和季节变化与海洋环境因素的关系,进行了较详细的讨论。 相似文献
5.
Methane in the western North Pacific 总被引：7，自引：0，他引：7
Shuich Watanabe Naoto Higashitani Nobuo Tsurushima Shizuo Tsunogai 《Journal of Oceanography》1995,51(1):39-60
The concentration of methane in about 400 seawater samples collected in the western North Pacific, mostly from 40°N to 5°S along 165°E was determined. While the concentration of methane in the surface water was slightly greater in the high-latitudes, it did not widely vary with a standard deviation of 0.29 n mol/l for a mean value of 2.49 n mol/l. The 90% confidence limit of the mean was 0.08 n mol/l. The degree of oversaturation in 1991 (31±4%) was not different from that in circa 1970. If we assume that this degree of oversaturation occurs in the entire oceans, the annual flux of methane becomes 6×1012g CH4. Both the concentrations of methane and chlorophylla were higher in the surface 100 m layer. However, the correlation between them was not well in the entire surface waters. This may indicate that the production of methane is not directly related to the photosynthetic process. The concentration of methane decreased gradually with increasing depth down to 1000 m. Its horizontally and vertically uniform concentration in the abyssal water suggests that the turnover time of methane in the oxic pelagic water is in the range between a few years and a few hundred years. 相似文献
6.
Seismic monitoring of western Pacific typhoons 总被引：2，自引：0，他引：2
Wu-Cheng Chi Wan-Jou Chen Ban-Yuan Kuo David Dolenc 《Marine Geophysical Researches》2010,31(4):239-251
Typhoons inflict large damage to societies, but are usually difficult to monitor in close proximity in real-time without expensive
instruments. Here we study the possibility of using seismic waveforms on the seafloor and on land to monitor the turning of
a far away or approaching typhoon. Up to 67% of the typhoons making landfall in Taiwan come from the eastern shore, so that
we deployed broadband ocean-bottom seismometers (OBSs) offshore eastern Taiwan in 2006 to study ground motion in close proximity
to a typhoon. Typhoons generate ocean waves, which generate pressure signals in the water column before being transmitted
to the seafloor as seismic waves and recorded by the OBSs. The ground motions on the seafloor correlate with locally increased
(ocean) wave heights and wave periods, suggesting that the ground motions are mostly induced by in situ or nearby pressure
fields, as shown by coherence function analyses. When a typhoon turns and changes wave-wave interaction near the source region,
a new set of en echelon patterns develops which can be observed by OBSs and land stations. Similar features occur when a typhoon crosses a landmass
and re-enters the ocean. The energy level ratio between the single-frequency and double-frequency microseisms also changes
abruptly when the typhoon turns. These features can potentially help near real-time early warning with little cost to complement
other conventional typhoon early warning methods. 相似文献
7.
Doron Nof 《Progress in Oceanography》1996,38(4):417-451
The western equatorial Atlantic is characterized by the formation and shedding of 3–4 large anticyclonic rings per year. These rings originate from the North Brazil Current which, in response to the vanishing wind stress curl (over the ocean interior), retroflects and turns eastward at around 4°N. After their formation and shedding the rings propagate toward the northwest along the South American coast carrying an annual average of about 4Sv. As such, the rings constitute an important part of the meridional heat flux in the Atlantic.The same cannot be said, however, of the western equatorial Pacific. Here, the situation is entirely different even though the South Equatorial Current retroflects at roughly the same latitude as its Atlantic counterpart, the North Brazil Current. Although the South Equatorial Current retroflection is flanked by two quasi-permanent eddies (the so-called Halmahera and the Mindanao eddies), these eddies are an integral part of the current itself and are not shed. Consequently, they are not associated with any meridional heat flux. An important question is, then, why the two oceans behave in such a fundamentally different way even though the source of the rings, the retroflected currents, are very similar in the two oceans.To answer this question, the two oceans are compared using recently developed analytical and numerical models for the western equatorial oceans. It is first pointed out that, according to recent developments in the modelling of the western equatorial Atlantic, the North Brazil Current retroflection rings are formed, shed and drift to the west because, in the Atlantic, this is the only way by which the momentum flux of the approaching and retroflecting current can be balanced. In this scenario, the northwestward flow force exerted by the approaching and retroflecting North Brazil Current (analogous to the force created by a rocket) is balanced by the southwestward force exerted by the rings as they are formed (analogous in some sense to the kickback associated with a firing gun).On the other hand, in the western equatorial Pacific, the formation and shedding of rings is unnecessary because the southward flowing Mindanao Current provides an alternative mechanism for balancing the northward momentum flux of the South Equatorial Current. This implies that it is the absence of a counter current (such as the Mindanao) in the western Atlantic that causes the formation and shedding of North Brazil Current rings. A remaining difficulty with the above scenario is that most colliding and retroflecting currents (i.e. the Mindanao and South Equatorial currents) are not “balanced” in the sense that they cannot be stationary but rather must drift along the coast. It is shown that, in the case of the western Pacific, the long-shore migration is arrested by the Indonesian Throughflow which allows the “unbalanced” fraction of the approaching currents to leak out into the Indian Ocean. This resolves the above difficulty and allows the retroflection to be approximately steady. 相似文献
8.
地中海是太平洋之外弧后盆地较为发育的海区。巴利阿里海盆和第勒尼安海盆是西地中海两个位置相邻、互有成因联系的弧后盆地。海盆莫霍面埋深分别为 1 2～ 1 5km和 1 0 km,热流密度分别为 1 0 0 m W/m2和 2 0 0 m W/m2 ,发育有大洋型磁条带异常 ,大洋钻探和拖网取样均采到了拉斑玄武岩。较之巴利阿里海盆 ,第勒尼安海盆更富年青性。两弧后盆地的成生演化是与欧洲板块与非洲 -阿普利亚板块的相互作用息息相关的。中新世 ,随着非洲 -阿普利亚板块向西、西北俯冲 ,科西嘉、撒丁裂离欧洲大陆 ,巴利阿里海盆被打开 ;上新世 ,阿普利亚微板块进一步俯冲 ,导致亚平宁与科西嘉、撒丁之间的裂离 ,形成第勒尼安海盆。 相似文献
9.
D. E. Gaskin 《新西兰海洋与淡水研究杂志》2013,47(1-2):1-20
The distribution and movements of sperm whales, Physeter catodon Linn., in the western South Pacific (latitudes 30–70° S, longitudes 150E‐150°W) are examined. An undetermined number of catches by nineteenth century American whaleships, 9,720 catches by pelagic fleets in 1961–70, and 427 sightings in 1967 are analysed and correlated with oceanographic data from Australian and New Zealand surveys. The proportion of females decreases southwards, abruptly at about latitude 44° S in the Tasman Sea, and at about 46–47° S east of New Zealand. Virtually no females occur south of 50° S. The male population density also decreases southwards: the density between 50–70° S appears to be less than 25% of that between 30–50° S. Sperm whales also appear to be less abundant in the eastern part of the region away from the New Zealand plateau, but more data are required. The pattern of distribution and its seasonal changes probably correlate with vertical temperature gradients of about 5°c in the upper 100 m of water, i.e., optimal conditions for squid schooling. Catch per unit effort in autumn is lower than in spring. A northward population shift in autumn is inferred, based on reduction of available food species and probable temperature tolerances of calves, most of which are born in February and March, towards the end of the southern summer. Some males overwinter in areas where suitable gradients persist, e.g., around the Chatham Islands. Possibly the summer surface temperature maxima south of the South Island are low enough to inhibit the passage of breeding schools with calves from one side of the New Zealand archipelago to the other. Sperm whales do not pass through Cook Strait normally. Thus, unless considerable mixing of stocks occurs north of New Zealand in winter, there may be two “unit stocks”, one oscillating seasonally between the central Tasman Sea and the Fiji‐Tonga region, and another (probably smaller) between the east coast of the South Island and the region just north of the Chatham Islands. 相似文献
10.
Ocean wave studies in western Cook Strait 总被引：1，自引：1，他引：0
11.
K. Crane E. Sundvor J. -P. Foucher M. Hobart A. M. Myhre S. LeDouaran 《Marine Geophysical Researches》1988,9(2):165-194
The northern Norwegian-Greenland Sea opened up as the Knipovich Ridge propagated from the south into the ancient continental Spitsbergen Shear Zone. Heat flow data suggest that magma was first intruded at a latitude of 75° N around 60 m.y.b.p. By 40–50 m.y.b.p. oceanic crust was forming at a latitude of 78° N. At 12 m.y.b.p. the Hovgård Transform Fault was deactivated during a northwards propagation of the Knipovich Ridge. Spreading is now in its nascent stages along the Molloy Ridge within the trough of the Spitsbergen Fracture Zone. Spreading rates are slower in the north than the south. For the Knipovich Ridge at 78° N they range from 1.5–2.3 mm yr-1 on the eastern flank to 1.9–3.1 mm yr-1 on the western flank. At a latitude of 75° N spreading rates increase to 4.3–4.9 mm yr-1.Thermal profiles reveal regions of off-axial high heat flow. They are located at ages of 14 m.y. west and 13 m.y. east of the northern Knipovich Ridge, and at 36 m.y. on the eastern flank of the southern Knipovich Ridge. These may correspond to episodes of increased magmatic activity; which may be related to times of rapid north-wards rise axis propagation.The fact that the Norwegian-Greenland Sea is almost void of magnetic anomalies may be caused by the chaotic extrusion of basalts from a spreading center trapped within the confines of an ancient continental shear zone. The oblique impact of the propagating rift with the ancient shear zone may have created an unstable state of stress in the region. If so, extension took place preferentially to the northwest, while compression occurred to the southeast between the opening, leaking shear zone and the Svalbard margin. This caused faster spreading rates to the northwest than to the southeast. 相似文献
12.
台湾海峡西部海域水体中的二氧化碳体系 总被引：7，自引：0，他引：7
据１９８４年５月至１９８５年２月的调查资料，计算了该水体中二氧化碳体系各要素的统计值，着重研究了它们的季节变化及其与水文，化学和生物因子的关系。结果表明该水体中ＰＣＯ２，ＣＯ２（Ｔ），ＣＯ＾２＾－３，ＨＣＯ３，∑ＣＯ２，ＣＯ＾２＾－３／∑ＣＯ２，ＨＣＯ３／∑ＣＯ２，ＨＣＯ２，ＣＯ２（Ｔ），ＣＯ＾２＾－３，∑ＣＯ２／Ｃｌ，Ωｃ，Ωａ和Ｃ：Ｎ：Ｐ平均值依次分别为２５１ｄＰａ，８．４３μｍｏｌ／ｄｍ×３ 相似文献
13.
Masahiro Endoh 《Journal of Oceanography》1973,29(1):16-27
A numerical experiment is made using a barotropic model for the western boundary currents. The time-dependent, non-linear vorticity equation is integrated with and without the variable of bottom topography. The inertial and frictional boundary flow is resolved with a fine grid size of 10 km. Connection of the western boundary currents with the general circulation is facilitated by giving the fixed Sverdrup transport at the eastern boundary of the model (400 km offshore).For the flat bottom topography, steady flow forRe=35 shows dynamical balance essentially of a frictional model. The transient response leading to the formation of the western boundary currents in the model seems to support theLighthill's theory (1969). ForRe=350, unsteady features revealed byBryan (1963) is re-established. A phenomenon of barotropic instability is also observed with sufficient resolution. For the model with a continental slope the steady flow is also obtained forRe=35. The boundary currents flow over the continental slope, deviating offshore as they flow northward. 相似文献
14.
Yoshimasa Toyota 《Journal of Oceanography》1988,44(4):157-162
The determination of dissolved Mn in sea water was carried out using a Chelex 100 resin and graphite furnace atomic absorption
spectrophotometer. The nearshore surface layer waters off the Straits of Kii had the highest Mn concentration of 6.40 n mol
kg−1 at these stations. Mn concentration of intermediate and deep water off the Straits of Kii ranged between 0.18 and 1.42 n
mol kg−1. Mn concentration in deep and bottom waters at the Mariana Trough were between 0.71 and 2.48 n mol kg−1. Sharp increases of Mn concentration near the bottoms were observed at two stations near the hydrothermal vents of the central
ridge of the Mariana Trough. 相似文献
15.
J. Acosta A. Muñoz P. Herranz C. Palomo M. Ballesteros M. Vaquero E. Uchupi 《Geo-Marine Letters》2001,21(3):123-130
Pockmarks ranging in width from <10 to 700 m, and with reliefs of 2 to 55 m were discovered in the Ibiza Channel and on the Balearic Promontory, Western Mediterranean, during a multibeam survey. In the Ibiza Channel the larger structures are found within a field of small craters less than 10 m wide and 5 m deep which give the seafloor an "orange peel" texture. The abundant 30 Ma-Present volcanic structures in the region suggests that most of the craters may have been formed by the escape of gases and associated waters via faults from a hydrothermal field beneath the surficial sediments. Others may be the result of neotectonism. 相似文献
16.
H. L. Davies J. B. Keene K. Hashimoto M. Joshima J. E. Stuart D. L. Tiffin 《Geo-Marine Letters》1986,6(4):181-191
The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m. 相似文献
17.
Yoshihisa Shirayama 《Journal of Oceanography》1989,45(1):83-93
I am deeply honored to have been awarded the 1988 Okada Prize of the Oceanographical Society of Japan. The present paper reviews my previous works regarding the ecology of deep-sea meiobenthos in the western Pacific area. The outline cen be summarized as follows:
相似文献
| 1) | On the basis of multivariate analyses, it was found that the rate of the organic-matter flux to the sea bed and the amount of the interstitial space within the sediment are the main factors regulating the abundance of meiofauna in the deep sea. |
| 2) | Two indices were proposed to characterize the vertical distribution of meiofauna in the sediment profile,i.e. their maximum depth in the sediment and the degree of their concentration in the surface layer of the sediment. The index of maximum depth was closely related to the oxygen concentration in the interstitial water. On the other hand, the index of degree of concentration in the surface of the sediment tended to be higher where the supply of food seemed lower. |
| 3) | Some taxonomically important species were found from the axis of the Izu-Ogasawara Trench. They arePliciloricus hadalis, the first species of the newest phylum Loricifera from the Pacific area, from the hadal deep sea and the fine clay sediment, andOccultammina profunda, the first infaunal species of Xenophyophorea, a group of rhizopod Protozoa. |
| 4) | The vertical distribution ofOccultammina profunda coincided well with the unusual distribution of210Pb in the sediment profile. The organisms concentrated as high as 500 dpm g–1 of210Pb in their stercomare and granellare. The steady state model confirmed that the species made the peculiar subsurface peak of210Pb in the sediment. |
| 5) | The depth in the sediment profile where the distinct peak of MnO2 can be seen showed strong correlation with the vertical distribution of meiofauna. This relationship suggests that oxygen concentration in the interstitial water regulates the structure of the characteristic three layers of the calcareous ooze in the deep sea. This idea was proven by the vertical distribution of free oxygen in the sediment calculated on the basis of respiration rate of deep-sea meiofauna measured using the cartesian diver technique. |
| 6) | Radio-isotope techniques used to measure the rates at which particulated organic matter was ingested and dissolved organic matter was absorbed, suggested that deep-sea meiofauna obtained a significant fraction of their energy by absorption. |
| 7) | The work carried out so far has revealed the important role of meiofauna in the benthic ecosystem, and emphasized the necessity for intensive research from various points of views on these microscopic organisms. |
18.
台湾海峡西部海域软质海底多毛类的生态 总被引：2，自引：0，他引：2
本文根据１９８４－１９８５年４航次底栖生物调查资料，首次全面地研究了台湾海峡西部海域多毛类的种类组成，数量分布及其与环境因子的关系。结果表明，该海域多毛类４０４种，习见种１９１种，区系属亚热带性质；平均生物量４．３３ｇ／ｍ＾２，平均栖息密度６８个／ｍ＾２；有沿岸性和外洋性两种明显不同的生态类型，前者位于沿岸水系常年控制海域，种类多，数量较大，后者位于南部粗粒沉积物分布区，种类较少；多毛类高数量区与 相似文献
19.
H. L. Davies J. B. Keene K. Hashimoto M. Joshima J. E. Stuart D. L. Tiffin 《Geo-Marine Letters》1987,6(4):181-191
The floor of the western Solomon Sea (for new bathymetric map see inside back cover of this issue) is dominated by the arched and ridged basement of the Solomon Sea Basin, the partly-sediment-filled New Britain Trench, and a more completely filled trench, the Trobriand Trough. There is a deep basin where the trenches join (149° Embayment), and a silled basin west of the New Britain Trench (Finsch Deep). Submarine canyons descend from the west and south to the 149° Embayment. Abyssal fans and plains are structurally defined and locally disturbed by young faults. Probable submerged pinnacle reefs stand in water depths as great as 1,200 m. 相似文献
20.
Abstract Aquifers occur in basalt deposits infilling valleys in the Western Springs catchment of Auckland City, and they discharge into small streams incised along the edges of major lava flows. Total run‐off from the area is >0.261 m3·s?1. Analyses by standard methods of twelve subsurface and surface waters show that flowing groundwaters have a low level of pollution (dissolved oxygen x = 7.6 mg·l?1, abuminoid nitrogen x = 0.038 mg·l?1, and total solids x = 188 mg·l?1). Surface waters and stagnant groundwater have high, but varying levels of biological activity. Although much of the dissolved solid content of all the waters (e.g., Ca2+, Mg2+, Na+, K+, SiO2) is consistent with the chemistry of the rocks of the catchment, particularly the glassy volcanic tuffs, for surface waters various sources of pollution also make significant contributions (e.g., leaking sewers, sewage overflows, combustion of fossil fuels, fertilisers, zoo animals). Apart from its iron level, the moderate volume (～.0.13 m3·s?1) of flowing groundwater is of suitable quality for domestic, industrial and irrigation needs. 相似文献