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1.
On the basis of our study of the present sediments in the northern part of the continental shelf of the South China Sea, this article clarifies our views that a "three-zone pattern" is the basic feature of transgression-type sedimentation.The classification of transgression-type sedimentation of the present continental shelf is based on: the close relationships between the formation of the present continental shelf and the position of the low sea level of the Wiirrn glacial stage, the genetic types and environmental features of sedimentary zoning, the relationship between the formation of glauconite with different maturity and the migration of coastline, the speed of transgression, and the overlying speed of sedimentation. We put forward the genetic name of the "three-zone pattern" to denote:1.The inner zouu, river mouth-coastal current sedimentary area;2.The intermediate zone, coastal current-sea current scouring-sedimentary area;3.The outer zone, sea current scouring area.All these are of significance  相似文献   

2.
MPmMARYDEVELOPMENTOFMDESERTIZATIONCONCEPTAubrevil(l949)definedthenewterm"desertification"asthetransforrnationfromtropicalandsubtropicalforestintospaxsegrasslands.Manydesertenvirorirnentresearchersbelievethatdesertandthedesertfficationenvironmentarenotonlytheresultofmodernen-vironmentdeterioraion,butwerealsopresentingeo1ogicalPeriodsheforetheoriginofInankind.Thewords`'desertification'and'desertiZaion'linEnglishlangUageliteraure,arecOllectivelycalled"ShaMoHua"inChinese-Thef…  相似文献   

3.
Bottom temperature variation (BTV) is a serious problem in determining the thermal gradient and heart flow of the sediments in shallow seas. The water depth of the East China Sea shelf is mostly below 150m, and the heat flow measurement is strongly affected by BTV. Following a statistical algorithm, we rechecked the temperature and thermal conductivity data of the cruises KX90-1 and KX91-1, carried out by a cooperation program of China and Japan, and calculate the heat flow in a site without long-term temperature record. The calculated heat flow in the site was 58.6±3.6 mW/m2, being just within the range of the drill heat flow value of East China Sea shelf. The inversed amplitude spectrum of BTV has a peak in frequency of 1/10 per year, and the annual component is also an important part. Comparison with two lakes of Lake Greifensee and Lac Leman (i.e. Lake Geneva), which are in different water depth, revealed that with increasing water depth, the peak of amplitude spectrum moved towards low frequency components. The heat flow values calculated in this paper and from petroleum bore hole in East China Sea shelf are much more close to that in southeast China than in Okinawa Trough. Supported by the National High Technology R&D Program of China (2004 AA616060)  相似文献   

4.
The Taiwan Warm Current Deep Water (or the East China Sea Upper Layer Water, or the East China Sea Subsurface Water) lying in the deep and bottom layers off the coast of Fujian-Zhejiang is one of the main watermasses in the continental shelf region of the western East China Sea. The hydrographical conditions and the fishery productions in this region are affected remarkably by the decline and growth of the Taiwan Warm Current Deep Water. Although the temperature, salinity and origin of the Taiwan Warm Current Deep Water have been investigated[3] by oceanographers the world over, there are up to now few papers published on its characteristics of ariations (seasonal and multiyear variations). Understanding of this problem will be helpful to further characterize this watermass. For this reason, in this paper, section 28°N representing the middle Taiwan Warm Current Deep Water and section 30°N representing the northern Taiwan Warm Current Deep Water are taken for examples, and the method of similar coefficient is used for analysis of this problem. Contribution No. 861 from the Institute of Oceanology, Academia Sinica. This paper was published in Chinese inOceanologia et Limnologia, Sinica 14 (4): 357–366.  相似文献   

5.
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6.
Clay minerals of 34 sediments collected from the northwestern continental shelf of the East China Sea have been determined by X-ray diffraction analysis. The clay mineral distribution is mainly controlled by the sediment source and the dominant circulation pattern. The predominant clay mineral in our study area is illite comprising more than 67% of the whole clay fraction. The highest concentration of illite (>68%) is found in the southeastern offshore parts beyond the reach of terrigenous input from the Jeju Island. It means that these illites are largely transported by the Kuroshio Current from the South China Sea (SCS). Smectite is highly concentrated in the northwest middle part and in the outer-shelf mud patch. It seems to be due to the high supply of smectite transported from China where fine-grained sediments are discharged from modern and ancient Huanghe (Yellow) River. The relatively high abundant kaolinite is likely derived from the Changjiang (Yangtze) River via the Taiwan Warm Current. In contrast, large amounts of chlorite and high chlorite/kaolinite ratios occur in the northwestern area, reflecting the transportation by the Yellow Sea Coastal Current from the southern Yellow Sea. The discrimination diagrams clearly show that the sediments in the northwestern East China Sea are ultimately sourced from Chinese rivers, especially from the Huanghe River, whereas the sediment in the northeast part might come from the Jeju Island. The muddy sediments of the Changjiang River’s submerged delta have much lower 87Sr/86Sr ratios (0.716 2–0.718 0) than those of the Shandong Peninsular mud wedge (0.721 6–0.724 9), which are supposed to be originated from the Huanghe River, suggesting the distribution pattern of 87Sr/86Sr ratios as a new tracer to discriminate the provenance of shelf sediments in the study area. The 87Sr/86Sr ratios of the outer-shelf muddy sediments ranged from 0.7169 to 0.7216 in a wide range and was between those of the Huanghe River and Changjiang River sediments, suggesting multiple sources of the sediment in the area.  相似文献   

7.
中日东海划界历经旷日持久而未能解决,中国主张尊重《联合国海洋法公约》(以下简称《公约》)中大陆架之自然延伸原则,采取不同于专属经济区的方法对大陆架进行划界,而日本则始终坚持采用中间线对中日东海大陆架和经济专属区作一揽子划界。无论从逻辑角度还是法理视角,日本主张在中日东海划界中适用中间线将混淆《公约》中专属经济区与大陆架两种制度。基于中日东海大陆架的地质与地貌特点以及公约对上述两种权利的不同规定,中日难以通过中间线对东海的海洋权益作出公平划分。中日两国应以《公约》为依据,分别对专属经济区和大陆架的划界作出安排,同时兼顾处理钓鱼岛群岛的主权归属问题,使中日东海划界问题得到妥善解决。  相似文献   

8.
Distribution of suspended matter in seawater in the Southern Yellow Sea is investigated in five regions: 1) the Northern Jiangsu bank, the highest TSM (total suspended matter) content region; 2) the high TSM content region off the Changjiang River mouth; 3) the high TSM content region off the Chengshan Cape; 4) the low TSM region off Haizhou Bay; 5) the central part of the Southern Yellow Sea, a low TSM content region. The vertical distribution of TSM is mainly characterized by a spring layer of suspended matter, written as “suspended-cline” whose genesis is related to storms in winter. In this paper, non-combustible components and grain sizes in suspended matter, relationship between suspended matter and bottom sediments, and salinity in seawater are described. Investigation result shows that, in this area, suspended matter comes mainly from resuspended bottom sediment and secondarily from present discharge loads from rivers and biogenic materials. Discharged sediments from the Huanghe River move around the Chengshan Cape and affect the northwestern region of this area. Sediments from the Changjiang River affect only the southern part and have little or no direct influence on the central deep region. Wave is the main factor affecting distribution of suspended matter. Water depth controls the critical depth acted on by waves. The cold water mass in the central region limits horizontal and vertical dispersions of terrigenous materials. Suspended matter here has the transitional properties of the epicontinental sea. Its concentration and composition are different from those of a semi-closed sea (such as the Bohai Sea) and those of the East China Sea outer continental shelf or those near oceanic areas.  相似文献   

9.
1 Introduction The Amery Ice Shelf, the largest ice shelf in East Antarctica, has a total surface area of about6.1×104km2. The ice shelf drains the grounded ice fromthe interior of the Lam- bert Glacier drainage basin thatcovers an area of larger than1.3…  相似文献   

10.
Based on the field data obtained during cruises on the shelf of the East China Sea from 1997 to 1999, seasonal variations of coastal upwelling on the inner shelf are discussed by using cross-shelf transect profiles and horizontal distributions of chemical and hydrographic variables. Results show that the coastal upwelling was year-round, but the areas and intensities of the upwelling were quite different in season. The coastal upwelling occurred in all of the coastal areas of the region in spring and summer, but in autumn only in the area off Zhejiang Province, and in winter in the area off Fujian Prov- ince. It was the strongest in summer and the weakest in winter. Geographically, it was the strongest in the area off Zhejiang Province and the weakest in the southmost or northmost parts of the East China Sea. The estimated nutrient fluxes upward into euphotic zone through coastal upwelling were quite large, es- pecially for phosphate, which contributed significantly to primary production and improved the nutrient structure of the coastal ecosystem in the East China Sea.  相似文献   

11.
In the Khumbu-and Khumbakarna Himalaya an ice stream network and valley glacier system has been reconstructed for the last glacial period (Würmian, Last Ice Age, Isotope stage 4–2, 60–18 Ka BP, Stage 0) with glaciogeomorphological and sedimentological methods. It was a part of the glacier system of the Himalaya and has communicated across transfluence passes with the neighbouring ice stream networks toward the W and E. The ice stream network has also received inflow from the N, from a Tibetan ice stream network, by the Kyetrak-Nangpa-Bote Koshi Drangka (Valley) in the W, by the W-Rongbuk glacier valley into the Ngozumpa Drangka (Valley), by the Central Rongbuk glacier valley into the Khumbu Drangka (Valley) and by the antecedent Arun Nadi transverse-valley in the E of the investigation area. The ice thickness of the valley glacier sections, the surface of which was situated above the snow-line, amounted to 1000–1450 m. The most extended parent valley glaciers have been measured approx. 70 km in length (Dudh Koshi glacier), 67 km (Barun-Arun glacier) and 80 km (Arun glacier). The tongue end of the Arun glacier has flowed down to c. 500 m and that of the Dudh Koshi glacier to c. 900 m asl. At heights of the catchment areas of 8481 (or 8475) m (Makalu), i.e., 8848 (or 8872) m (Mt. Everest, Sagarmatha, Chogolungma) this is a vertical distance of the Ice Age glaciation of c. 8000 m. The steep faces towering up to 2000 m above the névé areas of the 6000–7000 m-high surfaces of the ice stream network were located 2000–5000 m above the ELA. Accordingly, their temperatures were so low, that their rock surfaces were free of flank ice and ice balconies. From the maximum past glacier extension up to the current glacier margins, 13 (altogether 14) glacier stages have been differentiated and in part 14C-dated. They were four glacier stages of the late glacial period, three of the neoglacial period and six of the historical period. By means of 130 medium-sized valley glaciers the corresponding ELA-depressions have been calculated in comparison with the current courses of the orographic snow-line. The number of the glacier stages since the maximum glaciation approx. agrees with that e.g. in the Alps and the Rocky Mountains since the last glacial period. Accordingly, it is interpreted as an indication of the Würmian age (last glacial period) of the lowest ice margin positions. The current climatic, average glacier snow-line in the research area runs about 5500 m asl. The snow-line depression (ELA) of the last glacial period (Würm) calculated by four methods has run about 3870 m asl, so that an ELA-depression of c. 1630 m has been determined. This corresponds to a lowering of the annual temperature by c. 8, i.e., 10°C according to the specific humid conditions at that time.  相似文献   

12.
The variations of sea ice are different in different regions in Antarctica, thus have different impacts on local atmospheric circulation and global climatic system. The relationships between the sea ice in Ross Sea and Weddell Sea regions and the synoptic climate in summer of China are investigated in this paper via diagnostic analysis methods by using global sea ice concentration gridded data covering Jan. 1968 through Dec. 2002 obtained from Hadley Center, combined with Geopotential Height on 500hPa and 100hPa over North Hemisphere and monthly precipitation and air temperatures data covering the corresponding period over 160 meteorological stations in China obtained from CMA （ China Meteorological Administration）. Results disclose that both these two regions are of indicative meanings to the climate in summer of China. The Ross Sea Region is the key sea ice region to the precipitation in Northeast China in summer. More sea ice in this region in September will result in less precipitation in Northeast China in the following June. Weddell Sea Region is the key sea ice region to the air temperature in Northeast China in summer. More sea ice in this region in September will contribute to lower air temperature in Northeast China in the following June.  相似文献   

13.
Correspondence analysis and fuzzy C-means cluster methods were used to divide the stratigraphy of heavy mineral assemblages,and the sediment sources and depositional dynamics of the environment reconstructed.The assemblages were taken from marine sediments from the late Pleistocene to the Holocene in Core Q43 situated on the outer shelf of the East China Sea.Based on the variable boundaries of the mineral assemblage at 63 and 228 cmbsf (cm below sea floor),the core might have previously been divided into th...  相似文献   

14.
The environmental changes during the Late Pleistocene were more obvious in the eastern China than in other areas at the same latitude, which either between northern and southern, or between land and sea of the eastern China were mostly non-synchronous. The transitional period prior to the last glaciation came about in the northern part of the eastern China about 115,000 yr. ago. The desert environments of the inland of the north China were developed both in the glacial maximum and in the warm interglacial period, but the loess accumulation mostly took place during the glacial period. The sand dunes and the periglacial solifluctions in the lower Changjiang (Yangtze) River region were formed during the last glacial period. The event of lowest surface temperature occurred at 98,000 yr. B.P. and 59,000 yr. B.P. in the northern part of the South China Sea but not during the full-glacial stage. The phenomena mentioned . above were the result of the following reasons that the paleo-environmental changes in the  相似文献   

15.
Refraction seismic data obtained from a sonobuoy (SB7) in the East China Sea shelf marginal ridge was processed and interpreted. Intercept times and layer velocities were used to set up a one-dimension depth-velocity model based on which a two-dimenssion depth-velocity crustal model was established through two-dimension ray-tracing. The computation results showed that the upper crustal depth-velocity model beneath lineSB7 is composed of four layers with primary wave velocities of 1.80–2.20, 2.85–2.90, 3.24–3.34 and 4.55–6.00 m/s respectively. Neighbouring reflection seismic data and data on the East China Sea (ECS) regional geology were used to study the relationship between the velocities and their formation ages and also the contact relationship between the velocity boundaries. Contribution No. 3259, from the Institute of Oceanology, Chinese Academy of Sciences. Project 49376266 supported by NSFC.  相似文献   

16.
本义以东海陆架盆地地质调查和勘探开发的实际资料为依据，阐明了东海海底地形、地貌及地质特征；强调了近年来在石油地质学理论研究中的重要突破及石油勘探中的重要进展。文章分析了东海地层分布及其含油气规律；重点解剖了西湖凹陷及台北坳陷的油气资源富集特征；探讨了东海油气田早期开发利用方案；并指出了其开发的巨大经济价值和良好的前景。  相似文献   

17.
Altimeter wave period data obtained from continental shelf seas are analyzed in this paper. Empirical models are introduced for zero up-crossing and peak wave period calculation with TOPEX/POSEIDON data. Their performances are assessed using independent validation dataset in four sites in the open ocean of China. To provide more accurate wave period estimation, new coefficients are applied to reliable in situ data. Comparison of our estimated the wave periods with new linear calibrations based on independent data of Seapac 2100 deployed in the East China Sea and South China Sea showed that the accuracy was improved over estimates determined from earlier empirical models. Regional analysis indicated that the wave period model works better under wind sea condition.  相似文献   

18.
Evidence from lithology, foraminiferal assemblages, and high-resolution X-ray fluorescence scanning data of core SFK-1 indicates tidally influenced paleo-fluvial sedimentation during the last glacial maximum (LGM) on the outer shelf of the East China Sea. The paleo-fluvial deposits consist of river channel facies and estuarine incised-valley-filling facies. Different reflections on the seismic profile across core SFK-1 suggest that the river channels shifted and overlapped. River channel deposition formed early in the LGM when sea level fell and the estuary extended to the outer shelf. Channel sediments are yellowish-brown in color and rich in foraminifera and shell fragments owing to the strong tidal influence. Following the LGM, the paleo-river mouth retreated and regressive deposition of estuarine and incised-valley-filling facies with an erosion base occurred. The river channel facies and estuarine incised-valley-filling facies have clearly different sedimentary characteristics and provenances. The depositional environment of the paleoriver system on the wide shelf was reconstructed from the foraminiferal assemblages, CaCO3 content and Ca/Ti ratio. The main results of this study provide further substantial constraints on the recognition of late Quaternary stratigraphy and land-sea interactions on the ECS shelf.  相似文献   

19.
Diversion of the Yellow River is a unique geological event in offshore China, causing changes of the sedimentary environment in eastern China Seas. The last diversion took place in AD 1855, with the estuary diverted from the Yellow Sea into the Bohai Sea. The identification of the river diversion events in the shelf sediments would not only provide the definite ages for the sediments, but also give a clue for better understanding of the sedimentation in that area. In this study, 210 Pb, grain size, geochemical element, and foraminiferal data in core H205 from the north Yellow Sea were systematically investigated. A high-resolution sedimentary record was established, which was coupled with the Yellow River diversion and runoff changes. The results show that the foraminiferal composition and foraminiferal abundance of the sediments from the north Yellow Sea had good response to the Yellow River diversion in 1855. Before the change, shallow water assemblages dominated the foraminifera, and the abundance of each foraminiferal species was very low. After the diversion event, the abundance of most foraminifera increased sharply, with a maximum increase of 16 times, and the assemblage was still dominated by shallow water species. Furthermore, the changes in foraminiferal abundance in the core sediments corresponded well with the discharge fluctuation of the Yellow River since 1855. When the Yellow River began entering the Bohai Sea, the Yellow River water, which is rich in nutrients, along with the coastal currents affected the north Yellow Sea, increased the primary productivity in the north Yellow Sea, which is the main reason for the abrupt increase and fluctuation of foraminiferal abundance in this area. At the meantime, the East Asian winter monsoon could also promote the development of nearshore foraminiferal species by enhancing the coastal currents.  相似文献   

20.
Vertical profiles of chl-a and primary productivity in the middle continental shelf area and eddy area of the East China Sea were studied using data from a cruise in the East China Sea in February to March, 1997 and a cruise in July, 1998. The results showed that chl-a vertical distribution closely related to in situ hydrological and nutrient conditions. Chla-a concentration ranged from 0.22 to 0.35 mg/m3 and 0.93–1.09 mg/m3 in the eddy area and in the middle continental shelf area, respectively. In both areas, chl-a concentrations in deep layers were slightly higher than those in shallow layers, but was of the same order of magnitude. In summer, when a thermocline existed in the water column, highest chl-a concentrations appeared at the base of the thermocline layers in both areas. In the eddy area, chl-a concentration maximized at 31.743 mg/m3, and averaged 1.143 mg/m3 below 30 m depth. In the middle continental shelf area, the highest chl-a concentration was 2.120 mg/m3, the average was 1.168 mg/m3. The primary productivity reached 1418.76 mgC/(m2·d) in summer and 1360.69 mgC/(m2·d) in winter. In the eddy area, the primary productivity was 787.50 mgC/(m2·d) in summer and 159.04 mgC/(m2·d) in winter. Vertical carbon sinking rate from the deep layer to the bottom in both areas is also discussed in this paper. Contribution NO. 4183 from the Institute of Oceanology, Chinese Academy of Sciences. Project No. 49636210 supported by NSFC.  相似文献   

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