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1.
Michael S. Marlow Alan K. Cooper Shawn V. Dadisman Eric L. Geist Paul R. Carlson 《Marine and Petroleum Geology》1990,7(4)
Bowers Swell is a newly discovered bathymetric feature which is up to 90 m high, between 12 and 20 km wide, and which extends arcuately about 400 km along the northern and eastern sides of Bowers Ridge. The swell was first revealed on GLORIA sonographs and subsequently mapped on seismic reflection and 3.5 kHz bathymetric profiles. These geophysical data show that the swell caps an arcuate anticlinal ridge, which is composed of deformed strata in an ancient trench on the northern and eastern sides of Bowers Ridge. The trench fill beneath the swell is actively deforming, as shown by faulting of the sea floor and by thinning of the strata across the crest of the swell. Thinning and faulting of the trench strata preclude an origin for the swell by simple sediment draping over an older basement high. We considered several models for the origin of Bowers Swell, including folding and uplift of the underlying trench sediment during the interaction between the Pacific plate beneath the Aleutian Ridge and a remnant oceanic slab beneath Bowers Ridge. However, such plate motions should generate extensive seismicity beneath Bowers Ridge, which is aseismic, and refraction data do not show any remnant slab beneath Bowers Ridge. Another origin considered for Bowers Swell invokes sediment deformation resulting from differential loading and diapirism in the trench fill. However, diapirism is not evident on seismic reflection profiles across the swell. We favour a model in which sediment deformation and swell formation resulted from a few tens of kilometers of low seismicity motion by intraplate crustal blocks beneath the Aleutian Basin. This motion may result from the translation of blocks in western Alaska to the south-west, forcing the movement of the Bering Sea margin west of Alaska into the abyssal Aleutian Basin. 相似文献
2.
Eleven seismic reflection profiles across Shirshov Ridge and the adjacent deep-water sedimentary basins (Komandorsky and Aleutian Basins) are presented to illustrate the sediment distribution in the western Bering Sea. A prominent seismic reflecting horizon, Reflector P (Middle—Late Miocene in age), is observed throughout both the Aleutian and Komandorsky Basins at an approximate subbottom depth of 1 km. This reflector is also present, in places, on the flanks and along the crest of Shirshov Ridge. The thickness of sediments beneath Reflector P is significantly different within the two abyssal basins. In the Aleutian Basin, the total subbottom depth to acoustic basement (basalt?) is about 4 km, while in the Komandorsky Basin the depth is about 2 km.Shirshov Ridge, a Cenozoic volcanic feature that separates the Aleutian and Komandorsky Basins, is an asymmetric bathymetric ridge characterized by thick sediments along its eastern flank and steep scarps on its western side. The southern portion of the ridge has more structural relief that includes several deep, sediment-filled basins along its summit.Velocity data from sonobuoy measurements indicate that acoustic basement in the Komandorsky Basin has an average compressional wave velocity of 5.90 km/sec. This value is considerably larger than the velocities measured for acoustic basement in the northwestern Aleutian Basin (about 5.00 km/sec) and in the central Aleutian Basin (5.40–5.57 km/sec). In the northwestern Aleutian Basin, the low-velocity acoustic basement may be volcaniclastic sediments or other indurated sediments that are overlying true basaltic basement. A refracting horizon with similar velocities (4.6–5.0 km/sec) as acoustic basement dips steeply beneath the Siberian continental margin, reaching a maximum subbottom depth of about 8 km. The thick welt of sediment at the base of the Siberian margin may be the result of sediment loading or tectonic depression prior to Late Cenozoic time. 相似文献
3.
A. Zabanbark 《Oceanology》2009,49(5):729-739
The Bering Sea sedimentary basin comprises the Bering Sea and the adjacent intermontane depressions on the continents. It
includes the following subordinate sedimentary basins: the Norton; Bethel; Saint Lawrence; Anadyr; Navarin; Khatyrka; Saint
George; Bristol; Cook Inlet; and Aleutian consisting of the autonomous Aleutian, Bowers, and Komandor basins. All of them
exhibit significant geological similarity. The Middle and Upper Miocene terrigenous sequences, which are petroliferous through
the entire periphery of the Pacific Ocean, are characterized by their high petroleum resource potential in the Bering Sea
continental margin as well, which is confirmed by the oil and gas pools discovered in neighboring onshore lowlands. The younger
(Pliocene) and older (up to Upper Cretaceous) sedimentary formations are also promising with respect to hydrocarbons. The
integral potential oil and gas resources of the Bering Sea sedimentary basin, including the continental slopes, are estimated
by the US Geological Survey to be 1120 × 106 t and 965 × 109 m3, respectively. 相似文献
4.
5.
The sea-surface bioproductivity changes over the last 25 kyr were inferred from published data on 30 sediment cores from the open Northwest Pacific (NWP), Sea of Okhotsk, Bering Sea and Sea of Japan accounting for the glacioeustatic sea-level changes. A novel method was developed to compare the variations of several independent productivity proxies relative to the present-day values. During the Last Glacial Maximum, the bioproductivity in the Sea of Okhotsk and the western Bering Sea (BS) was lower than at present, whereas the southern and southeastern Bering Sea and the open NWP are characterized by enhanced bioproductivity. During the early deglacial stage, an increase in bioproductivity was estimated only for the southeastern Bering Sea. High and fairly high bioproductivity was estimated for Heinrich 1 in the open NWP, above the Umnak Plateau and on the Shirshov and Bowers Ridges in the Bering Sea. The high productivity in the Bering Sea, Sea of Okhotsk and NWP during the Bølling/Allerød was caused by the global warming and enhanced nutrient supply by meltwater from the continent. During the Early Holocene, high productivity was estimated for almost the entire NWP. The Late Holocene sea-surface bioproductivity was generally lower than that of the Early Holocene. Proposed factors that have controlled the sea-surface bioproductivity during the last 25 kyr include: the location of the sea ice margin, the river runoff, gradual flooding of the Bering Sea and the Sea of Okhotsk shelf areas, the water mass exchange between the marginal seas and the open NWP, the eolian supply and the deep vertical mixing of the water column. 相似文献
6.
S.N. Rodionov N.A. Bond J.E. Overland 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2560
Previous studies have found inconsistent results regarding how wintertime conditions in the Bering Sea relate to variations in the North Pacific climate system. This problem is addressed through analysis of data from the NCEP/NCAR Reanalysis for the period 1950–2003. Composite patterns of sea-level pressure, 500 hPa geopotential heights, storm tracks and surface air temperature are presented for four situations: periods of strong Aleutian Low, weak Aleutian Low, warm Bering Sea air temperatures, and cold Bering Sea air temperatures. Winter temperatures in the Bering Sea are only marginally related to the strength of the Aleutian Low, and are much more sensitive to the position of the Aleutian Low and to variations in storm tracks. In particular, relatively warm temperatures are associated with either an enhanced storm track off the coast of Siberia, and hence anomalous southerly low-level flow, or an enhanced storm track entering the eastern Bering Sea from the southeast. These latter storms do not systematically affect the mean meridional winds, but rather serve to transport mild air of maritime origin over the Bering Sea. The leading indices for the North Pacific, such as the NP and PNA, are more representative of the patterns of tropospheric circulation and storm track anomalies associated with the strength of the Aleutian Low than patterns associated with warm and cold wintertime conditions in the Bering Sea. 相似文献
7.
塔斯曼海位于西南太平洋地区，处于印度-澳大利亚板块和西兰板块之间，大地构造背景复杂。该地区是全球油气资源勘探的重点海域之一，但是国内对该地区的研究相当匮乏。本文根据塔斯曼海海域的自由空气重力异常对塔斯曼海海域的构造单元进行了划分，前人关于塔斯曼海的研究主要集中在Resolution海岭北部，我们认为塔斯曼海的范围应包括Resolution海岭以南，麦夸里海岭以西，塔斯曼断裂带以东的区域（即南部次盆）。结果显示，塔斯曼海域及邻区包括3个一级构造单元:东澳大利亚陆缘、西兰板块和塔斯曼海盆，且塔斯曼海盆可进一步划分为西部次盆、东部次盆和南部次盆。本文基于塔斯曼海域90 Ma以来的洋壳年龄数据编制了构造演化图，将塔斯曼海的形成演化过程分为4个阶段:（1）中生代陆内裂谷期（90~83 Ma BP）；（2）塔斯曼海扩张阶段（83~61 Ma BP）；（3）塔斯曼海北部扩张停止阶段（61~52 Ma BP）；（4）塔斯曼海南部改造阶段（52 Ma BP至今）。 相似文献
8.
Gleb Panteleev Max Yaremchuk Vladimir Luchin Dmitri Nechaev Takashi Kukuchi 《Journal of Oceanography》2012,68(4):485-496
Sea surface height anomalies observed by satellites in 1992–2010 are combined with monthly climatologies of temperature and salinity to estimate circulation in the southern Bering Sea. The estimated surface and deep currents are consistent with independent velocity observations by surface drifters and Argo floats parked at 1,000?m. Analysis reveals 1–3-Sv interannual transport variations of the major currents with typical intra-annual variability of 3–7?Sv. On the seasonal scale, the Alaskan Stream transport is well correlated with the Kamchatka (0.81), Near Strait (0.53) and the Bering Slope (0.37) currents. Lagged correlations reveal a gradual increase of the time the lags between the transports of the Alaskan Stream, the Bering Slope Current and the Kamchatka Current, supporting the concept that the Bering Sea basin is ventilated by the waters carried by the Alaskan Stream south of the Aleutian Arc and by the flow through the Near Strait. Correlations of the Bering Sea currents with the Bering Strait transport are dominated by the seasonal cycle. On the interannual time scale, significant negative correlations are diagnosed between the Near Strait transport and the Bering Slope and Alaskan Stream currents. Substantial correlations are also diagnosed between the eddy kinetic energy and Pacific Decadal Oscillation. 相似文献
9.
Results of the long-term study of the spatial and vertical distribution of the parasitic anadromous Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811) (Petromyzontidae) in the North Pacific and data on its size composition are given. This species is most frequent in the northwestern Sea of Japan and the western Bering Sea. The maximum concentrations are noted in waters of southern Primorye, southwestern Sakhalin, the northwestern part of the Sea of Okhotsk, and the northern part of the Bering Sea, which is probably explained by the increased number of its victims, Pacific salmon. Near the bottom, Pacific lampreys are extremely few and are primarily encountered at depths less that 400 m, and in the Pelagic zone, in the 100-m layer. The catches have contained Arctic lampreys having a total length of 15–79 cm. The lampreys of several size groups in the catches may indicate that L. camtschaticum spends not less than four years in the sea. No relationship has been found between the body length and the capture depth. Analyzed are the relationships between the body length and weight and the body length and the condition factor. The seasonal dynamics of these indices are considered. 相似文献
10.
白令海是冬季北极海冰变化最明显的区域之一,该区域海冰的季节和长期变化与局地的气候、水文环境和生态系统密切相关,并会影响我国的天气气候过程。为了识别该区冬季海冰的长期变化,基于Hadley中心数据,采用滑动t检验和线性回归分析方法对白令海1960–2020年海冰范围的变化趋势及其空间差异进行分析,并分析了海冰变化对大气环流等大气强迫的影响。结果表明:白令海冬季海冰范围在1960–2020年显著减小,20世纪70年代和2000年前后白令海海冰范围存在显著的均值突变。其过程中伴随着阿留申低压中心低压加强、核心位置向白令海西部偏移以及对应风场分布的变化,这个过程存在一个近20 a周期的振荡。同时,太平洋年代际震荡的相位变化可以通过改变海平面气压来调节经向风,改变进入白令海的热平流,进而影响白令海冬季海冰范围。因此,阿留申低压系统和北太平洋年代际振荡对冬季白令海海冰的变化起到重要的调节作用。 相似文献
11.
D. G. Masson 《Marine Geophysical Researches》1984,6(4):365-382
The northern Mascarene Basin, lying between Madagascar and the Seychelles Plateau in the north-west Indian Ocean, is marked at its north-western end by the Amirante Arc, an enigmatic ridge-trench complex superficially resembling an island arc. Structural trends in the area have been mapped using GLORIA sidescan sonar data, seismic reflection profiles and bathymetric maps. It is concluded that the north-west Mascarene Basin was created during the Late Cretaceous by sea-floor spreading about a north-west trending spreading axis cut by northeast trending transform faults. A major transform fault between the northern tip of Madagascar and the western margin of the Seychelles Plateau is proposed as a boundary between the Late Cretaceous Mascarene basin and the older Somali Basin to the north-west. The northern segment of the Amirante Ridge may mark part of the transform. The southern segment of the Ridge and its associated trench are, however, wholly contained within the Late Cretaceous ocean floor of the Mascarene Basin, and are best explained as compressional features related to a change in sea-floor spreading geometry in the Late Cretaceous or earliest Tertiary. Two models for the evolution of the Mascarene Basin are proposed, the major differences between them being the amount of subduction at the southern Amirante Arc and the timing of the initial separation between India and the Seychelles. 相似文献
12.
东海海城构造区划可分成2个盆地和3个隆起。东海盆地可划分成6个坳陷3个隆起;进而可分为16个次一级构造单元。盆地主要构造特征是东西成带,南北分块:即一个盆地三种结构,地层时代东西分带,构造运动与岩性东西分异,地质由西向东演化史;南北在深部地质结构、力学性质及(?)闭类型。构造格局及火成岩分布、沉积环境、地热梯度等诸方面有差异.文中讨论了构造特征形成的机制及盆地内重要的矿藏资源。 相似文献
13.
Marine geological and geophysical data together with drilling information indicate that the North African passive continental margin has been subjected to extension and wrenching after it collided with the northern part of Sicily. The area of the Tripolitania Basin, Jarrafa Trough, Melita and Medina Bank and the Ragusa-Malta Plateau has formed part of a sinking passive margin since the dispersal of Gondwanaland at about 180 My ago as observed from geohistory diagrams. A record of rifting in a NW-SE direction accompanied by dextral shear along the southern troughs is observed in seismic reflection data. The rifting started during the Neocomian and lasted until the Eocene when activity became minor. A pre-Middle Miocene period of northward subduction of oceanic crust is inferred from the geology in NE Sicily. Uplift of the northern part of the African margin after collision in the Middle Miocene is seen in wells in southern Sicily. After the Messinian a rift and dextral shear zone established itself across the African Margin from the Strait of Sicily to the Medina Ridge in the lonian Basin. The zone is marked by up to 1.7 km deep grabens, narrow active wrench faulted channels, volcanic fissures and local uplifted ‘Keilhorsts’ such as Malta. This zone, which varies in width from 100 to 35 km, forms the southern boundary of a microplate which includes Sicily. We speculate that the present motion of this microplate is partly due to the eastward movement of the Calabrian Arc with the Sicilian block over the last remaining oceanic lithosphere in the Eastern Mediterranean. 相似文献
14.
Takahiro Iida Sei-Ichi Saitoh 《Deep Sea Research Part II: Topical Studies in Oceanography》2007,54(23-26):2657
Seasonal and interannual variability of surface chlorophyll concentration in the Bering Sea was examined using Empirical Orthogonal Function (EOF) analysis of data obtained by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) from 1998 to 2002. The analysis of normalized monthly fields (removing temporal and spatial monthly means) shows that different temporal and spatial patterns are evident in the eastern and western Bering Sea during the spring bloom period. The first EOF mode explains 30% of the variability and shows how the eastern shelf break region and the western Bering Sea are out of phase during the spring bloom. The second EOF mode (17.6%) indicates a pattern involving the eastern shelf break region and the Kamchatka Basin. This strong east–west signal is linked by both surface winds and light. EOF modes of wind-speed anomalies, derived from Special Sensor Microwave Imager (SSM/I), and photosynthetically active radiance (PAR) from SeaWiFS, show a similar dipole feature where the east–west pattern is related to the position and strength of the Aleutian Low pressure system. In years when the Aleutian Low shifts from west to east, weaker wind stress facilitates the development of stratification resulting in a strong spring bloom in the western Bering Sea. The variability of spring chlorophyll has a strong connection with variability in atmospheric forcing in the Bering Sea. 相似文献
15.
法尔维海盆位于西南太平洋海域豪勋爵海丘东侧、新喀里多尼亚岛西侧，是全球油气勘探的前沿地区。但目前对于该海盆的构造演化研究较为薄弱，限制了该海盆油气资源的进一步勘探开发。本文通过从新西兰塔斯曼海数据库搜集到大量地球物理资料，使用2D Move软件，通过平衡剖面技术进行构造演化模拟，结合区域动力学机制将海盆北部和南部的构造演化分为7个阶段:(1)早白垩世至晚白垩世陆内裂谷阶段；(2)晚白垩世断坳过渡阶段；(3)始新世早期坳陷阶段；(4)始新世晚期一次构造反转阶段；(5)始新世至渐新世热沉降阶段；(6)渐新世至中新世二次构造反转阶段；(7)中新世至今海洋沉降阶段。由于海盆中部未发现有明显的二次构造反转阶段，所以将海盆中部的构造演化划分为5个阶段:(1)早白垩世至晚白垩世陆内裂谷阶段；(2)晚白垩世断坳过渡阶段；(3)始新世早期坳陷阶段；(4)始新世晚期构造反转阶段；(5)中新世至今海洋沉降阶段。此阶段海盆整体下坳，逐渐形成现今样貌。法尔维海盆北部受到区域构造活动影响较大，白垩系地层发育较多的断裂构造；海盆中部晚白垩统地层发生较多的底辟构造；海盆南部从形成至今，受到构造活动影响较小，发育地层完整，前新生代地层较厚。整个法尔维海盆北部构造活动较强，中部较弱，南部较小。沉积地层从北到南由厚变薄。 相似文献
16.
Venkatarathnam Kolla Lawrence Sullivan S.Stephen Streeter Marcus G. Langseth 《Marine Geology》1976,21(3):171-189
Data on bottom-water potential temperature, turbidity and current indications show that in the Southern Ocean west of the Kerguelen Plateau, Antarctic Bottom Water (AABW) of Weddell Sea origin spreads northwards from the Atlantic—Indian Basin in two directions: (1) AABW enters the Agulhas Basin through relatively deep areas in the Mid-Indian Ridge at 20–25°E and possibly at 35°E, and flows northwards into the Mozambique Basin as far as its northern limits; (2) a more easterly spreading path extends from the Atlantic—Indian Basin through the Crozet into the Madagascar, Mascarene, Somali and Arabian Basins. The passage in the western branch of the Indian Ridge for the AABW spreading from the Crozet into the Madagascar Basin appears to be at 29-26°S and 60–64°E.East of the Kerguelen Plateau in the South Indian Basin, the bottom water formed mainly along the Adélie Coast and Ross Sea travels west towards the Kerguelen Plateau and then parallel to it. This water finally flows eastwards hugging the Southeast Indian Ridge. Significant deviations from this general circulation pattern occur due to local topographic effects. Some AABW in the South Indian Basin exits through a passage at 120–125°E in the region of the Australian—Antarctic discordance in the Southeast Indian Ridge and enters the South Australian Basin and subsequently the Wharton Basin. This passage is clearly indicated by the northward extension of a cold, bottom-water tongue as shown by the temperature distribution in the region; the bottom-water effects in the passage are reflected in the high turbidity and current lineations on the sea floor.In the Southern Ocean basins, bottom-water turbidity is generally high, reflecting in part the strong bottom-water activity. The effects of AABW circulation on the sea floor—in the form of well-developed small- or large-scale current ripples and erosional/depositional features, manganese-nodule formations, and unconformities and reworking of sediments observed in cores — are also marked in these basins. Even though the AABW in the Wharton Basin is cold, its spreading effects on the sea floor are minimal in this basin in contrast to the basins west of the Mid-Indian Ridge at comparable latitudes. 相似文献
17.
Pacific ocean circulation based on observation 总被引：2，自引：1，他引：1
A thorough understanding of the Pacific Ocean circulation is a necessity to solve global climate and environmental problems.
Here we present a new picture of the circulation by integrating observational results. Lower and Upper Circumpolar Deep Waters
(LCDW, UCDW) and Antarctic Intermediate Water (AAIW) of 12, 7, and 5 Sv (106 m3s−1) in the lower and upper deep layers and the surface/intermediate layer, respectively, are transported to the North Pacific
from the Antarctic Circumpolar Current (ACC). The flow of LCDW separates in the Central Pacific Basin into the western (4
Sv) and eastern (8 Sv) branches, and nearly half of the latter branch is further separated to flow eastward south of the Hawaiian
Ridge into the Northeast Pacific Basin (NEPB). A large portion of LCDW on this southern route (4 Sv) upwells in the southern
and mid-latitude eastern regions of the NEPB. The remaining eastern branch joins nearly half of the western branch; the confluence
flows northward and enters the NEPB along the Aleutian Trench. Most of the LCDW on this northern route (5 Sv) upwells to the
upper deep layer in the northern (in particular northeastern) region of the NEPB and is transformed into North Pacific Deep
Water (NPDW). NPDW shifts southward in the upper deep layer and is modified by mixing with UCDW around the Hawaiian Islands.
The modified NPDW of 13 Sv returns to the ACC. The remaining volume in the North Pacific (11 Sv) flows out to the Indian and
Arctic Oceans in the surface/intermediate layer. 相似文献
18.
Fourteen midwater trawl collections to depths of 450 m to 1,400 m were taken at eleven stations in the Bering Sea and adjoining regions of the northern North Pacific by the R/V Hakuho Maru during the summer of 1975. A total of 29 kinds of fishes were identified. Mesopelagic fishes of the families Myctophidae, Gonostomatidae and Bathylagidae predominated in the catches, contributing 14 species (94%) of the fishes caught.Seventeen species of fishes were caught in the Bering Sea, and all of these are known from nearby areas. The mesopelagic fish fauna of the Bering Sea is similar to that in adjoining regions of the northern North Pacific Ocean: endemic species are rare or absent.
Stenobrachius nannochir was usually the most common mesopelagic fish in our catches.Stenobrachius leucopsarus is a diel vertical migrant that is usually the dominant mesopelagic fish in modified Subarctic waters of the northeastern Pacific. The change in dominance fromS. nannochir in the western Bering Sea toS. leucopsarus in the eastern Bering Sea is related to differences in oceanographic conditions. 相似文献
19.
20.
《Deep Sea Research Part II: Topical Studies in Oceanography》1999,46(1-2):475-499
Hydrographic data from the World Ocean Circulation Experiment (WOCE) and South Atlantic Ventilation Experiment (SAVE) in the region of transition between the Scotia Sea and the Argentine Basin are examined to determine the composition of the deep water from the Southern Ocean that enters the Atlantic, and to describe the pathways of its constituents. The deep current that flows westward against the Falkland Escarpment is formed of several superposed velocity cores that convey waters of different origins: Lower Circumpolar Deep Water (LCDW), Southeast Pacific Deep Water (SPDW), and Weddell Sea Deep Water (WSDW).Different routes followed by the WSDW upstream of, and through, the Georgia Basin, lead to distinctions between the Lower-WSDW (σ4>46.09) and the Upper-WSDW (46.04<σ4 <46.09). The Lower-WSDW flows along the South Sandwich Trench, then cyclonically in the main trough of the Georgia Basin. Although a fraction escapes northward to the Argentine Basin, a comparison of the WOCE data with those from previous programmes shows that this component had disappeared from the southwestern Argentine Basin in 1993/1994. This corroborates previous results using SAVE and pre-SAVE data. A part of the Upper-WSDW, recognizable from different θ–S characteristics, flows through the Scotia Sea, then in the Georgia Basin along the southern front of the Antarctic Circumpolar Current. Northward leakage at this front is expected to feed the Argentine Basin through the northern Georgia Basin. The SPDW is originally found to the south of the Polar Front (PF) in Drake Passage. The northward veering of this front allows this water to cross the North Scotia Ridge at Shag Rocks Passage. It proceeds northward to the Argentine Basin around the Maurice Ewing Bank. The LCDW at the Falkland Escarpment is itself subdivided in two cores, of which only the denser one eventually underrides the North Atlantic Deep Water (NADW) in the Atlantic Ocean. This fraction is from the poleward side of the PF in Drake Passage. It also crosses the North Scotia Ridge at Shag Rocks Passage, then flows over the Falkland Plateau into the Atlantic. The lighter variety, from the northern side of the PF, is thought to cross the North Scotia Ridge at a passage around 55°W. It enters the Argentine Basin in the density range of the NADW. 相似文献