The Thwaites Glacier in western Antarctica(Fig. 1) keeps glaciologists and climate scientists awake at night. The 120 kmwide glacier loses about 45 billion tonnes of ice each year, accounting for about 4% of global se...The Thwaites Glacier in western Antarctica(Fig. 1) keeps glaciologists and climate scientists awake at night. The 120 kmwide glacier loses about 45 billion tonnes of ice each year, accounting for about 4% of global sea level rise [1]. If it melted completely, sea levels would climb 65 cm, and follow-on effects could lead to a 3 m increase [2]. But if some scientists' vision becomes reality, in 10–15 years construction crews will sail into the Amundsen Sea off Antarctica to begin building an 80 km long underwater curtain that will shield the glacier from the warm currents that are accelerating its decline [3].展开更多
Fish scaleδ^(15)N(δ^(15)N_(sca))records trophic information of the whole life history for marine fishes.Data from gut content and values calculated from white muscle tissue(WMT)are insufficient for assessing trophic...Fish scaleδ^(15)N(δ^(15)N_(sca))records trophic information of the whole life history for marine fishes.Data from gut content and values calculated from white muscle tissue(WMT)are insufficient for assessing trophic level(TL)of marine fishes as they only provide the information of several months or even several days.Stable isotope analysis(SIA)of nitrogen was carried out in fish scales and WMT of 16 species from a total of 28 individuals captured from the Yellow Sea and northern East China Sea in October and November of 2019,aiming at discovering the correlation betweenδ^(15)N_(sca) and fish WMTδ^(15)N(δ^(15)NWMT),so as to useδ^(15)N_(sca) for the characterization of TLs of marine fish.Scales were analyzed without prior carbonate dissolution as a pre-processing step.TL calculated fromδ^(15)N_(sca) was compared to traditional TL formula calculated withδ^(15)N_(WMT) to estimate the accuracy.We found that there was a highly significant and positive correlation(r=0.830,P<0.001)betweenδ^(15)N_(sca) andδ^(15)N_(WMT).TL calculation results using fish scale(TL_(sca))and WMT(TL_(WMT))showed congruence(r=0.773,P<0.001),and the regression coefficient betweenδ^(15)N_(sca) andδ^(15)NWMT was used for calculating TLsca.The conversion was conducted for the purpose of comparison with previousδ^(15)N_(WMT)-based calculation results of TL.TLsca calculation results were 81.25%within the TL range of±10%calculated withδ^(15)NWMT.The findings in the present study showed thatδ^(15)N_(sca) is a viable technique for the characterization of the TL of marine fish and can help to predict food web and support the study of marine ecosystem.展开更多
In this paper, ECOMSED （Estuarine Coastal Ocean Model with sediment transport） model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED...In this paper, ECOMSED （Estuarine Coastal Ocean Model with sediment transport） model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED to simulate storm surge is validated by comparing model result with observed data. Sensitivity experiments are designed to study the influence of sea level rise on typhoon storm surge. Numerical experiment shows that influence of mean sea level rise on typhoon storm surge is non-uniform spatially and changes as typhoon process differs. Maybe fixed boundary method would weaken the influence of mean sea level rise on storm surge, and free boundary method is suggested for the succeeding study.展开更多
According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-st...According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-stands can be identified from the distribution of coral reef ages： 7300 - 6000 cal.aBP, 4800 - 4700 cal.aBP, 4300 - 4200 cal.aBP and 3100 - 2900 cal.aBP. The highest sea level occurred around 7300 - 6700 cal.aBP, and biological-morphological zones took their shape during the stage. The later coral reefs developed in ponds, depressions, and developed outwards on both sides of Luhuitou peninsula. The modern coral reefs are developing in out reef flat and reef-front slope. Moreover, the time of high sea levels in the northern South China Sea recorded by coral reefs in the Luhuitou peninsula can link up with that in other parts of South China Sea. That means the high sea levels in the South China Sea during the Holocene, which are relative to the warming climate, have the global background.展开更多
Sea level seasonal variations in the east of China seas from 2004 to 2006 are simulated by the advanced ROMS model. The results show similar sea level spatial features with TOPEX/Poseidon observations, with annual ran...Sea level seasonal variations in the east of China seas from 2004 to 2006 are simulated by the advanced ROMS model. The results show similar sea level spatial features with TOPEX/Poseidon observations, with annual ranges decreasing gradually from the sea coast to the Kuroshio region. By getting rid of wind stress in ROMS model, the simulated sea level results still show obvious seasonal variations. However, the phenomenon of sea level anomaly disappears in Min Zhe Current Coastwise （MZCF） and Su Bei current coastwise （SBCF）, and the change of it from coastal area to ocean recedes. The seal level difference between Bohai, Yellow Sea （BYS） and East China Sea （ECS） becomes weaker in spring and autumn. The annual differences decrease obviously, and the gradual change of annual ranges from seacoast to the Kuroshio almost disappears. The annual ranges in BYS are nearly identical. The annual range ratio without the wind stress to with the wind stress increases gradually from the sea coast to Kuroshio region.展开更多
Based on a large number of actual data, the author believe that the modem global warming and sea level rise resulted from climate warming after the cold front of the Little Ice Age about 200 years ago and the developm...Based on a large number of actual data, the author believe that the modem global warming and sea level rise resulted from climate warming after the cold front of the Little Ice Age about 200 years ago and the developmnet of the sea level rise phase. In the past 30 years, the rate of sea level rise was increasing, which is under the background of the average temperature uplift 0.2F°（0.11℃）every 10 years in succession from the 1980s to the past 10 years this century. On the basis of the absolute and relative sea-level rise rate that was calculated from the tidal data during the same period at home and abroad in the last 30 years, in accordance with the resolutions of the 2010 climate conference in Cancun, at the same time, considering the previous prediction and research, the world＇s sea levels and the relative sea level in Tianjin, Shanghai, Dongying, Xiamen, Haikou and other coastal cities that have severe land subsidence in 2050 and 2100 are calculated and evaluated.展开更多
Ouvéa Island in New Caledonia emerges as a new sea level standard. It has excellent morphological records of former sea level positions at interglacial high-stands as well as records of Holocene changes in sea le...Ouvéa Island in New Caledonia emerges as a new sea level standard. It has excellent morphological records of former sea level positions at interglacial high-stands as well as records of Holocene changes in sea level from a maximum at about +1.5 m via a significant +70 cm level of sub-recent, probably 17<sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century, age to a stable to falling sea level in present time.</span>展开更多
In the Late Cambrian, the North China Platform was a typical carbonate ramp platform. The Upper Cambrian of the northern part of the North China Platform is famous for the development of bioherm limestones and storm c...In the Late Cambrian, the North China Platform was a typical carbonate ramp platform. The Upper Cambrian of the northern part of the North China Platform is famous for the development of bioherm limestones and storm calcirudites and can be divided from bottom to top into the Gushan, Changshan and Fengshan formations. In this set of strata, the deep-ramp mudstone and marls and the shallow-ramp packstones and grainstones constitute many carbonate meter-scale cycles of subtidal type. More tidal-flat dolomites are developed in the Upper Cambrian of the southern margin of the North China platform, in which limestone and dolomite beds also constitute many carbonate meter-scale cycles of the peritidal type. These cycles are marked by a variety of litho-facies successions. There are regularly vertical stacking patterns of meter-scale cycles in long-term third-order sequences, which is the key to discerning such sequences. Third- order sequence is marked by a particular sedimentary-facies succession that is the result of the environment-changing process of deepening and shoaling, which is genetically related to third-order sea level changes. Furthermore, four third- order sequences can be grouped in the Upper Cambrian of the North China Platform. The main features of these four third -order sequences in the northern part of the platform can be summarized as follows: firstly, sequence-boundaries are characterized by drowning unconformities; secondly, the sedimentary-facies succession is generally constituted by one from deep-ramp facies to shallow-ramp facies; thirdly, a succession of “CS (?)+HST” (i.e., “condensed section and high- stand system”) forms these four third-order sequences. The chief features for the third-order sequences in the southern part of the North China Platform comprises: more dolomites are developed in the HSTs of third-order sequences and also developed more carbonate meter-scale cycles of peritidal types; the sedimentary-facies succession of the third-order sequences is marked by “shallow ramp-tidal flat”; the sequence boundaries are characterized by exposure punctuated surfaces. According to the changes for the third-order sequences from the north to the south, a regular sequence- stratigraphic framework can be established. From cycles to sequences, the study of sequence stratigraphy from litho-facies successions to sedimentary-facies successions exposes that as follows: meter-scale cycles that are used as the basic working unit actually are litho-facies successions formed by the mechanism of a punctuated aggradational cycle, and third -order sequences that are constituted by regularly vertical stacking patterns of meter-scale cycles are marked by sedimentary-facies successions. On the basis of the changing curve of water depth at each section, the curve of the relative third-order sea level changes in the late Cambrian of the North China Platform can be integrated qualitatively from changing curve of water depth. The correlation of Late Cambrian long-term sea level changes between North China and North America demonstrates that there are not only similarities but also differences, reflecting control of long-term sea level changes both by global eustacy and by regional factors.展开更多
Future potential sea level change in the South China Sea （SCS） is estimated by using 24 CMIP5 models under different representative concentration pathway （RCP） scenarios. By the end of the 21st century （2081–210...Future potential sea level change in the South China Sea （SCS） is estimated by using 24 CMIP5 models under different representative concentration pathway （RCP） scenarios. By the end of the 21st century （2081–2100 relative to 1986–2005）, the multimodel ensemble mean dynamic sea level （DSL） is projected to rise 0.9, 1.6, and 1.1 cm under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, resulting in a total sea level rise （SLR） of 40.9, 48.6, and 64.1 cm in the SCS. It indicates that the SCS will experience a substantial SLR over the 21st century, and the rise is only marginal larger than the global mean SLR. During the same period, the steric sea level （SSL） rise is estimated to be 6.7, 10.0, and 15.3 cm under the three scenarios, respectively, which accounts only for 16%, 21% and 24% of the total SLR in this region. The changes of the SSL in the SCS are almost out of phase with those of the DSL for the three scenarios. The central deep basin has a slightly weak DSL rise, but a strong SSL rise during the 21st century, compared with the north and southwest shelves.展开更多
Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is com...Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is compared with the harmonic analysis result of hourly sea level data from 19 tide gauges for more than 19 years. It is indicated that the long-term mean sea level variation affects notably tidal waves in this region. Generally, the tidal amplitude increases when the mean sea level rises, but this relationship may be inverse for some sea areas. The maximal variation of tidal amplitude takes place in the zones near the Fujian coast and the Zhejiang coast, rather than the shallowest Bohai Sea. The maximum increase of M2 amplitude can exceed about 15 cm corresponding to the 60 cm rise of the mean sea level along the Fujian coast. The other regions with large variations of tidal amplitude are those along the Jiangsu coast, the south-east coast of Shandong, and the south-east coast of Dalian. The propagation of tidal waves is also related to mean sea level variation, and the tidal phase-lag decreases generally when the mean sea level rises. Almost all the regions where the tidal phase-lag increases with rising mean sea level are close to amphidromic points, meanwhile the spatial area of such regions is very small. Because the influence of mean sea level variation upon tidal waves is spatially marked, such spatial effect should be considered in calculation of the tidal characteristic value and engineering water level. In the region where the amplitudes of the major tidal constituents increase, the probable maximum high water level becomes higher, the probable maximum low water level becomes lower, and both design water level andcheck water level increase obviously. For example, the design water level at Xiamen increases by 13.5 cm due to the variation of tidal waves when the mean sea level rises 60 cm, the total increase of design water level being 73.5 cm.展开更多
Mangroves,widely distributed along the coasts of tropical China,are influenced by Asia monsoon,relative sea level change and enhanced human activity.To predict the impacts of future climate change on mangrove ecosyste...Mangroves,widely distributed along the coasts of tropical China,are influenced by Asia monsoon,relative sea level change and enhanced human activity.To predict the impacts of future climate change on mangrove ecosystems,it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments.In this study,we quantitatively partitioned buried organic matter(OM)sources,collected from a vulnerable mangrove swamp in the Qinzhou Bay of northwestern South China Sea,using a ternary end-member mixing model of δ^13C and C:N values.Mangrove-derived OM(MOM)contribution was used as a tracer for mangrove development since 2.34 cal ka BP.This information,together with paleoclimate records(i.e.,speleothem δ^18O values,sea level change,grain size parameters)and human activity,was used to divide mangrove development into three stages during the late Holocene:relative flourish(2.34-1.13 cal ka BP),relative degradation(1.13-0.15 cal ka BP)and further degradation(0.15-0 cal ka BP).Before 1.13 cal ka BP,mangroves flourished with a high MOM contribution((88.9±10.6)%),corresponding to stable and high sea level under a warm and humid climate.After 1.13 cal ka BP,rapid fall in relative sea level coupled with the strengthening of the Asian winter monsoon,resulted in mangrove degradation and MOM reduction((62.4±18.9)%).Compared with air temperature and precipitation,the relative sea level fall was the main controlling factor in mangrove development before entering the Anthropocene(the time of the Industrial Revolution).After^150 cal a BP,reclamation of mangrove swamps to shrimp ponds is the main factor causing mangrove degradation and MOM reduction.展开更多
This paper first introduces procedures leading to the establishment of Late Permian-Middle Triassic sea level change curve of Yangtze platform. Bathymetric curves extracted from curve of habitat types are first trans...This paper first introduces procedures leading to the establishment of Late Permian-Middle Triassic sea level change curve of Yangtze platform. Bathymetric curves extracted from curve of habitat types are first transformed to sea level curves stage by stage. Comparison between curves of Yangtze and the world reveals that because the Late Permian marine sequences are lacking in most parts of the world, the Late Permian to Griesbachian curve of Yangtze may serve as an important reference for further revision of the world curve. The Early-Middle Triassic short-term changes of Yangtze are briefly concordant with those of Haq's world curve, whereas their long-term changes are discordant. The latter, however, is representative of the East Asian regions affected by the Indosinian orogeny. Basically the third cycles of Yangtze and the world are only pertly concordant, and even in concordant cases their concrete boundaries are not coincident. This indicater that sea level changes are not strictly synchronous over the world. It seems that the 1st and 2nd cycles (supercycles and megacycles) may be world-wide, but not the 3rd cycles.展开更多
Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large u...Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.展开更多
Sea level variability in the East China Sea （ECS） was examined based primarily on the analysis of TOPEX/Poseidon altimetry data and tide gauge data as well as numerical simulation with the Princeton ocean model （PO...Sea level variability in the East China Sea （ECS） was examined based primarily on the analysis of TOPEX/Poseidon altimetry data and tide gauge data as well as numerical simulation with the Princeton ocean model （POM）. It is concluded that the inter-annual sea level variation in the ECS is negatively correlated with the ENSO index, and that the impact is more apparent in the southern area than in the northern area. Both data analysis and numerical model results also show that the sea level was lower during the typical E1 Niflo period of 1997 to 1998. E1 Nifio also causes the decrease of the annual sea level variation range in the ECS. This phenomenon is especially evident in the southern ECS. The impacts of wind stress and ocean circulation on the sea level variation in the ECS are also discussed in this paper. It is found that the wind stress most strongly affecting the sea level was in the directions of 70° and 20° south of east,, respectively, over the northern and southern areas of the ECS. The northwest wind is particularly strong when E1 Nifio occurs, and sea water is transported southeastward, which lowers the sea level in the southern ECS. The sea level variation in the southern ECS is also significantly affected by the strengthening of the Kuroshio. During the strengthening period of the Kuroshio, the sea level in the ECS usually drops, while the sea level rises when the Kuroshio weakens.展开更多
The ensemble optimal interpolation （EnOI） is applied to the regional ocean modeling system （ROMS） with the ability to assimilate the along-track sea level anomaly （TSLA）. This system is tested with an eddy-resol...The ensemble optimal interpolation （EnOI） is applied to the regional ocean modeling system （ROMS） with the ability to assimilate the along-track sea level anomaly （TSLA）. This system is tested with an eddy-resolving system of the South China Sea （SCS）. Background errors are derived from a running seasonal ensemble to account for the seasonal variability within the SCS. A fifth-order localization function with a 250 km localization radius is chosen to reduce the negative effects of sampling errors. The data assimilation system is tested from January 2004 to December 2006. The results show that the root mean square deviation （RMSD） of the sea level anomaly decreased from 10.57 to 6.70 cm, which represents a 36.6% reduction of error. The data assimilation reduces error for temperature within the upper 800 m and for salinity within the upper 200 m, although error degrades slightly at deeper depths. Surface currents are in better agreement with trajectories of surface drifters after data assimilation. The variance of sea level improves significantly in terms of both the amplitude and position of the strong and weak variance regions after assimilating TSLA. Results with AGE error （AGE） perform better than no AGE error （NoAGE） when considering the improvements of the temperature and the salinity. Furthermore, reasons for the extremely strong variability in the northern SCS in high resolution models are investigated. The results demonstrate that the strong variability of sea level in the high resolution model is caused by an extremely strong Kuroshio intrusion. Therefore, it is demonstrated that it is necessary to assimilate the TSLA in order to better simulate the SCS with high resolution models.展开更多
Because of the environmental and socioeconomic impacts of anthropogenic sea level rise （SLR）, it is very important to understand the processes leading to past and present SLRs towards more reliable future SLR projec...Because of the environmental and socioeconomic impacts of anthropogenic sea level rise （SLR）, it is very important to understand the processes leading to past and present SLRs towards more reliable future SLR projections. A regional ocean general circulation model （ROGCM）, with a grid refinement in the Bohai, Yellow, and East China Seas （BYECSs）, was set up to project SLR induced by the ocean dynamic change in the 21st century. The model does not consider the contributions from ice sheets and glacier melting. Data of all forcing terms required in the model came from the simulation of the Community Climate System Model version 3.0 （CCSM3） under the International Panel on Climate Change （IPCC）-A2 scenario. Simulation results show that at the end of the 21st century, the sea level in the BYECSs will rise about 0.12 to 0.20 m. The SLR in the BYECSs during the 21st century is mainly caused by the ocean mass redistribution due to the ocean dynamic change of the Pacific Ocean, which means that water in the Pacific Ocean tends to move to the continental shelves of the BYECSs, although the local steric sea level change is another factor.展开更多
The East China Sea shelf basin is a key area for setting up the sea level changes of Cenozoic in the West Pacific. Based upon the characteristics of seismic reflection, the analysis of sequence stratigraphy and depos...The East China Sea shelf basin is a key area for setting up the sea level changes of Cenozoic in the West Pacific. Based upon the characteristics of seismic reflection, the analysis of sequence stratigraphy and depositional system, the high resolution chronostratigraphic framework has been set up by using the data of micropaleontologic biozone fossils. The relative sea level change curve has been set up by combining analysis of paleoecology, genetic facies, specific sedimentary structures and on lap recognized from the seismic profiles with study of geochemical characteristics. There are 4 2nd order basin cycles showing the long term sea level changes, and 22 3rd order cycles showing short term ones with relative changing ranges of 0-150 m. Transgression and regression showing long term sea level changes bear asymmetric feature, which indicates that the speed of transgression is faster than that of regression. There are a lot of differences when compared with Haq ’s curve. The sequence stratigraphic framework has also been set up and 3 tectonic sequences, 7 supersequences and 19 sequences have been subdivided for Tertiary in the East China Sea shelf basin. On the basis of detailed analysis of genetic facies and log facies, 9 sedimentary systems, 20 depositional assemblages and many genetic facies have also been recognized and investigated. Based on the studies mentioned above, the favorable source and reservoir facies of gas and petroleum are indicated.展开更多
The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmy...The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmyear^-1 in T/P sea-level rise from October 1992 to September 2002. Sea level change due to temperature variation （the thermosteric sea level） is discussed. The results are compared with TOPEX/Poseidon altimeter data in the same temporal span at different spatial scales. It is indicated that the thermal effect accounts for 86% and 73% of the observed seasonal variability in the northern and southern hemispheres, respectively. The TOPEX/Poseidon observed sea level lags behind the TSL by 2 months in the zonal band of 40%-60% in both the northern and southern hemispheres. Systematic differences of about 1-2 cm between TOPEX/Poseidon observations and thermosteric sea level data are obtained. The potential causes tbr these differences include water exchange among the atmosphere, land, and oceans, and some possible deviations in thermosteric contribution estimates and geophysical corrections to the TOPEX/Poseidon data.展开更多
Sea level anomalies observed by altimeter during the 1993-2006 period, thermosteric sea level anomalies estimated by using subsurface temperature data produced by Ishii and SODA reanalysis data, tide gauge records and...Sea level anomalies observed by altimeter during the 1993-2006 period, thermosteric sea level anomalies estimated by using subsurface temperature data produced by Ishii and SODA reanalysis data, tide gauge records and HOAPS freshwater flux data were analyzed to investigate the long term sea level change and the water mass balance in the South China Sea, The altime- ter-observed sea level showed a rising rate of （3.5±0.9）mmyr-1 during the period 1993-2006, but this figure was considered to have been highly distorted by the relatively short time interval and the large inter-decadal variability, which apparently exists in both the thermosteric sea level and the observed sea level. Long term thermosteric sea level from 1945 to 2004 gave a rising rate of 0.15±0.06 mmyr-1. Tide gauge＇data revealed this discrepancy and the regional distributions of the sea-level trends. Both the ＇real＇ and the ther- mosteric sea level showed a good correspondence to ENSO： decreasing during El Nino years and increasing during La Nina years. Amplitude and phase differences between the ＇real＇ sea level and the thermosteic sea level were substantially revealed on both sea- sonal and interannual time scales. As one of the possible factors, the freshwater flux might play an important role in balancing the water mass.展开更多
The Triassic in the Qomolongma area, southern Tibet, was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rifting. From the Induan to Rhaetian, 12 depositional sequences (...The Triassic in the Qomolongma area, southern Tibet, was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rifting. From the Induan to Rhaetian, 12 depositional sequences (3rd order) have been recognized, which can be grouped into 5 sequence sets and in turn make up a well defined mesosequence (2nd order). Among the recognized marine transgressions, those at 250 Ma, 239 Ma, 231 Ma and 223 Ma respectively are particularly of significance and can be correlated widely across continents. The study shows that in Triassic the Qomolongma area experienced a sedimentary evolution from epicontinental sea to rift basin with the turning point at ca 228 Ma. During the early and middle epochs, the area was under epeiric sea, with carbonate ramp to mixed shoal environments predominant. In the late Carnian, the strong extension initiated listric faulting, thus resulting in rapid basement subsidence and the onset of a rift basin. From the late Norian to Rhaetian, it manifested as a rapid basin filling process in the area. Coupled with long term sea level fall, the excessive terrigenous influx led to the shift of environment from deep water prodelta to shore and finally to fluvial plain.展开更多
文摘The Thwaites Glacier in western Antarctica(Fig. 1) keeps glaciologists and climate scientists awake at night. The 120 kmwide glacier loses about 45 billion tonnes of ice each year, accounting for about 4% of global sea level rise [1]. If it melted completely, sea levels would climb 65 cm, and follow-on effects could lead to a 3 m increase [2]. But if some scientists' vision becomes reality, in 10–15 years construction crews will sail into the Amundsen Sea off Antarctica to begin building an 80 km long underwater curtain that will shield the glacier from the warm currents that are accelerating its decline [3].
基金supported by the Scientific Research Foundation of Hainan Tropical Ocean University(No.RHDRC202312)the Major Science and Technology Project of Yazhou Bay Innovation Institute of Hainan Tropical Ocean University:Research on Hainan Coastal Marine Ecological Environment and Carbon Sink(No.2022CXYZD002).
文摘Fish scaleδ^(15)N(δ^(15)N_(sca))records trophic information of the whole life history for marine fishes.Data from gut content and values calculated from white muscle tissue(WMT)are insufficient for assessing trophic level(TL)of marine fishes as they only provide the information of several months or even several days.Stable isotope analysis(SIA)of nitrogen was carried out in fish scales and WMT of 16 species from a total of 28 individuals captured from the Yellow Sea and northern East China Sea in October and November of 2019,aiming at discovering the correlation betweenδ^(15)N_(sca) and fish WMTδ^(15)N(δ^(15)NWMT),so as to useδ^(15)N_(sca) for the characterization of TLs of marine fish.Scales were analyzed without prior carbonate dissolution as a pre-processing step.TL calculated fromδ^(15)N_(sca) was compared to traditional TL formula calculated withδ^(15)N_(WMT) to estimate the accuracy.We found that there was a highly significant and positive correlation(r=0.830,P<0.001)betweenδ^(15)N_(sca) andδ^(15)N_(WMT).TL calculation results using fish scale(TL_(sca))and WMT(TL_(WMT))showed congruence(r=0.773,P<0.001),and the regression coefficient betweenδ^(15)N_(sca) andδ^(15)NWMT was used for calculating TLsca.The conversion was conducted for the purpose of comparison with previousδ^(15)N_(WMT)-based calculation results of TL.TLsca calculation results were 81.25%within the TL range of±10%calculated withδ^(15)NWMT.The findings in the present study showed thatδ^(15)N_(sca) is a viable technique for the characterization of the TL of marine fish and can help to predict food web and support the study of marine ecosystem.
文摘In this paper, ECOMSED （Estuarine Coastal Ocean Model with sediment transport） model is employed to simulate storm surge process caused by typhoon passing across East China Sea in nearly years. Capability of ECOMSED to simulate storm surge is validated by comparing model result with observed data. Sensitivity experiments are designed to study the influence of sea level rise on typhoon storm surge. Numerical experiment shows that influence of mean sea level rise on typhoon storm surge is non-uniform spatially and changes as typhoon process differs. Maybe fixed boundary method would weaken the influence of mean sea level rise on storm surge, and free boundary method is suggested for the succeeding study.
基金We gratefully acknowledge the financial supports from the National Natural Science Foundation of China(Grant No.49976015).
文摘According to the field survey and ^14C dating at Luhuitou, southern Hainan Island, a subsiding area, the authors conclude the high sea level history recorded by coral reef in the Holocene. At least 4 sea level high-stands can be identified from the distribution of coral reef ages： 7300 - 6000 cal.aBP, 4800 - 4700 cal.aBP, 4300 - 4200 cal.aBP and 3100 - 2900 cal.aBP. The highest sea level occurred around 7300 - 6700 cal.aBP, and biological-morphological zones took their shape during the stage. The later coral reefs developed in ponds, depressions, and developed outwards on both sides of Luhuitou peninsula. The modern coral reefs are developing in out reef flat and reef-front slope. Moreover, the time of high sea levels in the northern South China Sea recorded by coral reefs in the Luhuitou peninsula can link up with that in other parts of South China Sea. That means the high sea levels in the South China Sea during the Holocene, which are relative to the warming climate, have the global background.
基金supported by the National Natural Science Foundation of China(contract No.41006002,No.41206013 and No.41106004)Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography of SOA(contract No.SOED1305)+3 种基金Open Fund of the Key Laboratory of Ocean Circulation and Waves,Chinese Academy of Sciences(contract No.KLOCAW1302)the Public Science and Technology Research Funds Projects of Ocean(contract No.200905001,No.201005019,and No.201205018)the Natural Science Foundation of State Ocean Administration(contract No.2012202,No.2012223,and No.2012224)Open Fund of Key Laboratory of Physical Oceanography,MOE(contract of Song jun)
文摘Sea level seasonal variations in the east of China seas from 2004 to 2006 are simulated by the advanced ROMS model. The results show similar sea level spatial features with TOPEX/Poseidon observations, with annual ranges decreasing gradually from the sea coast to the Kuroshio region. By getting rid of wind stress in ROMS model, the simulated sea level results still show obvious seasonal variations. However, the phenomenon of sea level anomaly disappears in Min Zhe Current Coastwise （MZCF） and Su Bei current coastwise （SBCF）, and the change of it from coastal area to ocean recedes. The seal level difference between Bohai, Yellow Sea （BYS） and East China Sea （ECS） becomes weaker in spring and autumn. The annual differences decrease obviously, and the gradual change of annual ranges from seacoast to the Kuroshio almost disappears. The annual ranges in BYS are nearly identical. The annual range ratio without the wind stress to with the wind stress increases gradually from the sea coast to Kuroshio region.
基金supported by the National Natural Science Foundation of China (No.40940025)Natural Science Fund of Tianjin (No.07ZCGYSF02400 and 09JCYBJC07400)+2 种基金National ‘973’ Project (No.2007CB411807)State Oceanic Administration of the marine atmosphere-Chemistry and global change open fund of Key Laboratory (No.GCMAC0806)the National Natural Science Fund(No.41006002)
文摘Based on a large number of actual data, the author believe that the modem global warming and sea level rise resulted from climate warming after the cold front of the Little Ice Age about 200 years ago and the developmnet of the sea level rise phase. In the past 30 years, the rate of sea level rise was increasing, which is under the background of the average temperature uplift 0.2F°（0.11℃）every 10 years in succession from the 1980s to the past 10 years this century. On the basis of the absolute and relative sea-level rise rate that was calculated from the tidal data during the same period at home and abroad in the last 30 years, in accordance with the resolutions of the 2010 climate conference in Cancun, at the same time, considering the previous prediction and research, the world＇s sea levels and the relative sea level in Tianjin, Shanghai, Dongying, Xiamen, Haikou and other coastal cities that have severe land subsidence in 2050 and 2100 are calculated and evaluated.
文摘Ouvéa Island in New Caledonia emerges as a new sea level standard. It has excellent morphological records of former sea level positions at interglacial high-stands as well as records of Holocene changes in sea level from a maximum at about +1.5 m via a significant +70 cm level of sub-recent, probably 17<sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century, age to a stable to falling sea level in present time.</span>
文摘In the Late Cambrian, the North China Platform was a typical carbonate ramp platform. The Upper Cambrian of the northern part of the North China Platform is famous for the development of bioherm limestones and storm calcirudites and can be divided from bottom to top into the Gushan, Changshan and Fengshan formations. In this set of strata, the deep-ramp mudstone and marls and the shallow-ramp packstones and grainstones constitute many carbonate meter-scale cycles of subtidal type. More tidal-flat dolomites are developed in the Upper Cambrian of the southern margin of the North China platform, in which limestone and dolomite beds also constitute many carbonate meter-scale cycles of the peritidal type. These cycles are marked by a variety of litho-facies successions. There are regularly vertical stacking patterns of meter-scale cycles in long-term third-order sequences, which is the key to discerning such sequences. Third- order sequence is marked by a particular sedimentary-facies succession that is the result of the environment-changing process of deepening and shoaling, which is genetically related to third-order sea level changes. Furthermore, four third- order sequences can be grouped in the Upper Cambrian of the North China Platform. The main features of these four third -order sequences in the northern part of the platform can be summarized as follows: firstly, sequence-boundaries are characterized by drowning unconformities; secondly, the sedimentary-facies succession is generally constituted by one from deep-ramp facies to shallow-ramp facies; thirdly, a succession of “CS (?)+HST” (i.e., “condensed section and high- stand system”) forms these four third-order sequences. The chief features for the third-order sequences in the southern part of the North China Platform comprises: more dolomites are developed in the HSTs of third-order sequences and also developed more carbonate meter-scale cycles of peritidal types; the sedimentary-facies succession of the third-order sequences is marked by “shallow ramp-tidal flat”; the sequence boundaries are characterized by exposure punctuated surfaces. According to the changes for the third-order sequences from the north to the south, a regular sequence- stratigraphic framework can be established. From cycles to sequences, the study of sequence stratigraphy from litho-facies successions to sedimentary-facies successions exposes that as follows: meter-scale cycles that are used as the basic working unit actually are litho-facies successions formed by the mechanism of a punctuated aggradational cycle, and third -order sequences that are constituted by regularly vertical stacking patterns of meter-scale cycles are marked by sedimentary-facies successions. On the basis of the changing curve of water depth at each section, the curve of the relative third-order sea level changes in the late Cambrian of the North China Platform can be integrated qualitatively from changing curve of water depth. The correlation of Late Cambrian long-term sea level changes between North China and North America demonstrates that there are not only similarities but also differences, reflecting control of long-term sea level changes both by global eustacy and by regional factors.
基金The National Basic Research Program(973 Program)of China under contract No.2010CB950501the National Natural Science Foundation of China under contract No.41276035the National Natural Science Foundation of China–Shandong Province Joint Fund of Marine Science Research Centers under contract No.U1406404
文摘Future potential sea level change in the South China Sea （SCS） is estimated by using 24 CMIP5 models under different representative concentration pathway （RCP） scenarios. By the end of the 21st century （2081–2100 relative to 1986–2005）, the multimodel ensemble mean dynamic sea level （DSL） is projected to rise 0.9, 1.6, and 1.1 cm under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, resulting in a total sea level rise （SLR） of 40.9, 48.6, and 64.1 cm in the SCS. It indicates that the SCS will experience a substantial SLR over the 21st century, and the rise is only marginal larger than the global mean SLR. During the same period, the steric sea level （SSL） rise is estimated to be 6.7, 10.0, and 15.3 cm under the three scenarios, respectively, which accounts only for 16%, 21% and 24% of the total SLR in this region. The changes of the SSL in the SCS are almost out of phase with those of the DSL for the three scenarios. The central deep basin has a slightly weak DSL rise, but a strong SSL rise during the 21st century, compared with the north and southwest shelves.
文摘Tidal waves in the East China Sea are simulated numerically with POM(Princeton Ocean Model) model for normal mean sea level, 30 cm higher, 60 cm higher, and 100 cm higher, respectively, and the simulated result is compared with the harmonic analysis result of hourly sea level data from 19 tide gauges for more than 19 years. It is indicated that the long-term mean sea level variation affects notably tidal waves in this region. Generally, the tidal amplitude increases when the mean sea level rises, but this relationship may be inverse for some sea areas. The maximal variation of tidal amplitude takes place in the zones near the Fujian coast and the Zhejiang coast, rather than the shallowest Bohai Sea. The maximum increase of M2 amplitude can exceed about 15 cm corresponding to the 60 cm rise of the mean sea level along the Fujian coast. The other regions with large variations of tidal amplitude are those along the Jiangsu coast, the south-east coast of Shandong, and the south-east coast of Dalian. The propagation of tidal waves is also related to mean sea level variation, and the tidal phase-lag decreases generally when the mean sea level rises. Almost all the regions where the tidal phase-lag increases with rising mean sea level are close to amphidromic points, meanwhile the spatial area of such regions is very small. Because the influence of mean sea level variation upon tidal waves is spatially marked, such spatial effect should be considered in calculation of the tidal characteristic value and engineering water level. In the region where the amplitudes of the major tidal constituents increase, the probable maximum high water level becomes higher, the probable maximum low water level becomes lower, and both design water level andcheck water level increase obviously. For example, the design water level at Xiamen increases by 13.5 cm due to the variation of tidal waves when the mean sea level rises 60 cm, the total increase of design water level being 73.5 cm.
基金The National Natural Science Foundation of China under contract Nos 41576067 and 41576061the Basic Scientific Fund for National Public Research Institutes of China under contract No.2017Q03the National Basic Research Program(973Program)of China under contract No.2010CB951203
文摘Mangroves,widely distributed along the coasts of tropical China,are influenced by Asia monsoon,relative sea level change and enhanced human activity.To predict the impacts of future climate change on mangrove ecosystems,it can be understood by reconstructing past mangrove dynamics using proxies preserved in coastal sediments.In this study,we quantitatively partitioned buried organic matter(OM)sources,collected from a vulnerable mangrove swamp in the Qinzhou Bay of northwestern South China Sea,using a ternary end-member mixing model of δ^13C and C:N values.Mangrove-derived OM(MOM)contribution was used as a tracer for mangrove development since 2.34 cal ka BP.This information,together with paleoclimate records(i.e.,speleothem δ^18O values,sea level change,grain size parameters)and human activity,was used to divide mangrove development into three stages during the late Holocene:relative flourish(2.34-1.13 cal ka BP),relative degradation(1.13-0.15 cal ka BP)and further degradation(0.15-0 cal ka BP).Before 1.13 cal ka BP,mangroves flourished with a high MOM contribution((88.9±10.6)%),corresponding to stable and high sea level under a warm and humid climate.After 1.13 cal ka BP,rapid fall in relative sea level coupled with the strengthening of the Asian winter monsoon,resulted in mangrove degradation and MOM reduction((62.4±18.9)%).Compared with air temperature and precipitation,the relative sea level fall was the main controlling factor in mangrove development before entering the Anthropocene(the time of the Industrial Revolution).After^150 cal a BP,reclamation of mangrove swamps to shrimp ponds is the main factor causing mangrove degradation and MOM reduction.
文摘This paper first introduces procedures leading to the establishment of Late Permian-Middle Triassic sea level change curve of Yangtze platform. Bathymetric curves extracted from curve of habitat types are first transformed to sea level curves stage by stage. Comparison between curves of Yangtze and the world reveals that because the Late Permian marine sequences are lacking in most parts of the world, the Late Permian to Griesbachian curve of Yangtze may serve as an important reference for further revision of the world curve. The Early-Middle Triassic short-term changes of Yangtze are briefly concordant with those of Haq's world curve, whereas their long-term changes are discordant. The latter, however, is representative of the East Asian regions affected by the Indosinian orogeny. Basically the third cycles of Yangtze and the world are only pertly concordant, and even in concordant cases their concrete boundaries are not coincident. This indicater that sea level changes are not strictly synchronous over the world. It seems that the 1st and 2nd cycles (supercycles and megacycles) may be world-wide, but not the 3rd cycles.
基金funded by the National Basic Research Program of China(Grant Nos.2010CB950102 and 2009CB421406)the Nansen Scientific Society(Norway)part of the SeaLev projects at the Centre of Climate Dynamics/Bjerknes Center in Bergen
文摘Sea level rise （SLR） is one of the major socioeconomic risks associated with global warming. Mass losses from the Greenland ice sheet （GrIS） will be partially responsible for future SLR, although there are large uncertainties in modeled climate and ice sheet behavior. We used the ice sheet model SICOPOLIS （Simulation COde for POLythermal Ice Sheets） driven by climate projections from 20 models in the fifth phase of the Coupled Model Intercomparison Project （CMIP5） to estimate the GrlS contribution to global SLR. Based on the outputs of the 20 models, it is estimated that the GrIS will contribute 0-16 （0-27） cm to global SLR by 2100 under the Representative Concentration Pathways （RCP） 4.5 （RCP 8.5） scenarios. The projected SLR increases further to 7-22 （7-33） cm with 2~basal sliding included. In response to the results of the multimodel ensemble mean, the ice sheet model projects a global SLR of 3 cm and 7 cm （10 cm and 13 cm with 2~basal sliding） under the RCP 4.5 and RCP 8.5 scenarios, respectively. In addition, our results suggest that the uncertainty in future sea level projection caused by the large spread in climate projections could be reduced with model-evaluation and the selective use of model outputs.
基金supported by the National Basic Research Program of China(973 program,Grant No 2007CB411807)the National Natural Science Foundation of China(Grants No40976006 and 40906002)+1 种基金the National Marine Public Welfare Research Project of China(Grant No201005019)the Project of Key Laboratory of Coastal Disasters and Defense of Ministry of Education of China(Grant No200802)
文摘Sea level variability in the East China Sea （ECS） was examined based primarily on the analysis of TOPEX/Poseidon altimetry data and tide gauge data as well as numerical simulation with the Princeton ocean model （POM）. It is concluded that the inter-annual sea level variation in the ECS is negatively correlated with the ENSO index, and that the impact is more apparent in the southern area than in the northern area. Both data analysis and numerical model results also show that the sea level was lower during the typical E1 Niflo period of 1997 to 1998. E1 Nifio also causes the decrease of the annual sea level variation range in the ECS. This phenomenon is especially evident in the southern ECS. The impacts of wind stress and ocean circulation on the sea level variation in the ECS are also discussed in this paper. It is found that the wind stress most strongly affecting the sea level was in the directions of 70° and 20° south of east,, respectively, over the northern and southern areas of the ECS. The northwest wind is particularly strong when E1 Nifio occurs, and sea water is transported southeastward, which lowers the sea level in the southern ECS. The sea level variation in the southern ECS is also significantly affected by the strengthening of the Kuroshio. During the strengthening period of the Kuroshio, the sea level in the ECS usually drops, while the sea level rises when the Kuroshio weakens.
基金The Major State Basic Research Development Program of China under contract Nos 201-1CB403606 and 2011CB403500the National Natural Science Foundation of China under contract Nos 41222038,41076011and 41206023the National Marine Environmental Forecasting Center Operational Development Foundation of the State Oceanic Administration of China under contract No.2013002
文摘The ensemble optimal interpolation （EnOI） is applied to the regional ocean modeling system （ROMS） with the ability to assimilate the along-track sea level anomaly （TSLA）. This system is tested with an eddy-resolving system of the South China Sea （SCS）. Background errors are derived from a running seasonal ensemble to account for the seasonal variability within the SCS. A fifth-order localization function with a 250 km localization radius is chosen to reduce the negative effects of sampling errors. The data assimilation system is tested from January 2004 to December 2006. The results show that the root mean square deviation （RMSD） of the sea level anomaly decreased from 10.57 to 6.70 cm, which represents a 36.6% reduction of error. The data assimilation reduces error for temperature within the upper 800 m and for salinity within the upper 200 m, although error degrades slightly at deeper depths. Surface currents are in better agreement with trajectories of surface drifters after data assimilation. The variance of sea level improves significantly in terms of both the amplitude and position of the strong and weak variance regions after assimilating TSLA. Results with AGE error （AGE） perform better than no AGE error （NoAGE） when considering the improvements of the temperature and the salinity. Furthermore, reasons for the extremely strong variability in the northern SCS in high resolution models are investigated. The results demonstrate that the strong variability of sea level in the high resolution model is caused by an extremely strong Kuroshio intrusion. Therefore, it is demonstrated that it is necessary to assimilate the TSLA in order to better simulate the SCS with high resolution models.
基金supported by the National Natural Science Foundation of China(Grants No.41206021 and 41276018)the National Basic Research Program of China(Grant No.2012CB955601)+2 种基金the Young Scientist Foundation of the State Oceanic Administration,China(Grant No.2012251)the U.S.National Science Foundation Belmont Forum Program(Grant No.ICER-1342644)the GASI-03-01-01-09
文摘Because of the environmental and socioeconomic impacts of anthropogenic sea level rise （SLR）, it is very important to understand the processes leading to past and present SLRs towards more reliable future SLR projections. A regional ocean general circulation model （ROGCM）, with a grid refinement in the Bohai, Yellow, and East China Seas （BYECSs）, was set up to project SLR induced by the ocean dynamic change in the 21st century. The model does not consider the contributions from ice sheets and glacier melting. Data of all forcing terms required in the model came from the simulation of the Community Climate System Model version 3.0 （CCSM3） under the International Panel on Climate Change （IPCC）-A2 scenario. Simulation results show that at the end of the 21st century, the sea level in the BYECSs will rise about 0.12 to 0.20 m. The SLR in the BYECSs during the 21st century is mainly caused by the ocean mass redistribution due to the ocean dynamic change of the Pacific Ocean, which means that water in the Pacific Ocean tends to move to the continental shelves of the BYECSs, although the local steric sea level change is another factor.
文摘The East China Sea shelf basin is a key area for setting up the sea level changes of Cenozoic in the West Pacific. Based upon the characteristics of seismic reflection, the analysis of sequence stratigraphy and depositional system, the high resolution chronostratigraphic framework has been set up by using the data of micropaleontologic biozone fossils. The relative sea level change curve has been set up by combining analysis of paleoecology, genetic facies, specific sedimentary structures and on lap recognized from the seismic profiles with study of geochemical characteristics. There are 4 2nd order basin cycles showing the long term sea level changes, and 22 3rd order cycles showing short term ones with relative changing ranges of 0-150 m. Transgression and regression showing long term sea level changes bear asymmetric feature, which indicates that the speed of transgression is faster than that of regression. There are a lot of differences when compared with Haq ’s curve. The sequence stratigraphic framework has also been set up and 3 tectonic sequences, 7 supersequences and 19 sequences have been subdivided for Tertiary in the East China Sea shelf basin. On the basis of detailed analysis of genetic facies and log facies, 9 sedimentary systems, 20 depositional assemblages and many genetic facies have also been recognized and investigated. Based on the studies mentioned above, the favorable source and reservoir facies of gas and petroleum are indicated.
基金supported by the NSFC projects (Nos. 40376005, 40676013, 40506006 and 40676015)the SRFDP project (No. 20060423014)+1 种基金NCET-04-0646 Key Scientific Research Program (No. 2007CB411807)National Key Technology R&D Program (No. 2007BAC- 03A06-06)
文摘The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmyear^-1 in T/P sea-level rise from October 1992 to September 2002. Sea level change due to temperature variation （the thermosteric sea level） is discussed. The results are compared with TOPEX/Poseidon altimeter data in the same temporal span at different spatial scales. It is indicated that the thermal effect accounts for 86% and 73% of the observed seasonal variability in the northern and southern hemispheres, respectively. The TOPEX/Poseidon observed sea level lags behind the TSL by 2 months in the zonal band of 40%-60% in both the northern and southern hemispheres. Systematic differences of about 1-2 cm between TOPEX/Poseidon observations and thermosteric sea level data are obtained. The potential causes tbr these differences include water exchange among the atmosphere, land, and oceans, and some possible deviations in thermosteric contribution estimates and geophysical corrections to the TOPEX/Poseidon data.
基金supported by the National Basic Research Program of China through Grant No. 973-2007CB- 411807
文摘Sea level anomalies observed by altimeter during the 1993-2006 period, thermosteric sea level anomalies estimated by using subsurface temperature data produced by Ishii and SODA reanalysis data, tide gauge records and HOAPS freshwater flux data were analyzed to investigate the long term sea level change and the water mass balance in the South China Sea, The altime- ter-observed sea level showed a rising rate of （3.5±0.9）mmyr-1 during the period 1993-2006, but this figure was considered to have been highly distorted by the relatively short time interval and the large inter-decadal variability, which apparently exists in both the thermosteric sea level and the observed sea level. Long term thermosteric sea level from 1945 to 2004 gave a rising rate of 0.15±0.06 mmyr-1. Tide gauge＇data revealed this discrepancy and the regional distributions of the sea-level trends. Both the ＇real＇ and the ther- mosteric sea level showed a good correspondence to ENSO： decreasing during El Nino years and increasing during La Nina years. Amplitude and phase differences between the ＇real＇ sea level and the thermosteic sea level were substantially revealed on both sea- sonal and interannual time scales. As one of the possible factors, the freshwater flux might play an important role in balancing the water mass.
基金This paper is supported jointly by the National Natural Science Foundation( No.4982 5 10 2 ) and the Ministry of Science and Te
文摘The Triassic in the Qomolongma area, southern Tibet, was deposited under an extensional tectonic setting from the Pangea supercontinent to continental rifting. From the Induan to Rhaetian, 12 depositional sequences (3rd order) have been recognized, which can be grouped into 5 sequence sets and in turn make up a well defined mesosequence (2nd order). Among the recognized marine transgressions, those at 250 Ma, 239 Ma, 231 Ma and 223 Ma respectively are particularly of significance and can be correlated widely across continents. The study shows that in Triassic the Qomolongma area experienced a sedimentary evolution from epicontinental sea to rift basin with the turning point at ca 228 Ma. During the early and middle epochs, the area was under epeiric sea, with carbonate ramp to mixed shoal environments predominant. In the late Carnian, the strong extension initiated listric faulting, thus resulting in rapid basement subsidence and the onset of a rift basin. From the late Norian to Rhaetian, it manifested as a rapid basin filling process in the area. Coupled with long term sea level fall, the excessive terrigenous influx led to the shift of environment from deep water prodelta to shore and finally to fluvial plain.
