An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag, East China Sea. This suite has been well imaged offshore through 2D and 3D seismic surveys, showing a close ...An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag, East China Sea. This suite has been well imaged offshore through 2D and 3D seismic surveys, showing a close relationship with CO2 content in nearby gas discoveries. A new observational model, which incorporates simple upward propagation, simple horizontal propagation, and transgressive propagation, was proposed to interpret these sill intrusions. In this model, the source magma of the saucer-shaped sills was injected from their lowest points near the center. The transgressive propagation can be interpreted as a combination of the vertical and horizontal propagation. Most shallow sub-volcanic intrusions in the Jiaojiang sag exhibit fingered characteristics, both vertically and horizontally. The vertical fingered propagation produced saucer-shaped sills arranged in the flower style. Along the brims of lower sills could usually be found the upper sills, which are interpreted to have formed simultaneously with or later than the lower feeder sills. In the second type, the chilled paths of the older sills were reutilized by subsequent intrusions. The horizontal fingered propagation formed sheet intrusions that exhibit groove, lobate, tubular, and crevasse splay- like geometry in plan view. In 3D view, the sheet intrusions have still preserved the lower center and higher rim that similar with the sub-rounded saucer-shaped sills. Although fracture propagation may be important, flow inflation was the key mechanism of magma intrusion. Further consideration of the mechanisms underlying sill formation may help explain the fingered characteristics of sill propagation.展开更多
Variations in coastline geometry caused by coastal engineering affect tides, storm surges, and storm tides. Three cluster land reclamation projects have been planned for construction in the Jiaojiang Estuary during th...Variations in coastline geometry caused by coastal engineering affect tides, storm surges, and storm tides. Three cluster land reclamation projects have been planned for construction in the Jiaojiang Estuary during the period from 2011 to 2023. They will cause significant changes in coastline geometry. In this study, a surge-tide coupled model was established based on a three-dimensional finite-volume coastal ocean model （FVCOM）. A series of numerical experiments were carried out to investigate the effects of variations in coastline geometry on tides, storm surges, and storm tides. This model was calibrated using data observed at the Haimen and Ruian gauge stations and then used to reproduce the tides, storm surges, and storm tides in the Jiaojiang Estuary caused by Typhoon Winnie in 1997. Results show that the high tide level, peak storm surge, and high storm tide level at the Haimen Gauge Station increased along with the completion of reclamation projects, and the maximum increments caused by the third project were 0.13 m, 0.50 m, and 0.43 m, respectively. The envelopes with maximum storm tide levels of 7.0 m and 8.0 m inside the river mouth appeared to move seaward, with the latter shifting 1.8 km, 3.3 km, and 4.4 km due to the first project, second project, and third project, respectively. The results achieved in this study contribute to reducing the effects of, and preventing storm disasters after the land reclamation in the Jiaojiang Estuary.展开更多
A quantitative description of a long-term series of aquatic environmental factors and their spatial distributions was generated using measured data from the Jiaojiang Estuary from 1982 to 2011. The aquatic environment...A quantitative description of a long-term series of aquatic environmental factors and their spatial distributions was generated using measured data from the Jiaojiang Estuary from 1982 to 2011. The aquatic environmental factors included suspended matter, salinity, and nutrients. Based on these factors, the aquatic ecosystem health in the Jiaojiang Estuary over the last 30 years was analyzed. The results indicated that the suspended matter concentration in the estuary was mainly affected by the amounts of suspended sediment and solid waste, with the value fluctuating over a long period, and the range of high concentration expanded continually; the salinity was mainly affected by precipitation and surface water resources, showing an overall decreasing trend, and the region with low salinity moved seaward and toward the reclamation areas; and the nutritional status, mainly affected by discharge of industrial wastewater and domestic sewage, was satisfactory in the 1980s and 1990s, but the status became severe in recent years. Reclamation had a great influence on these three factors： high reclamation strength led to a significant increase in the suspended matter concentration and a deterioration of the nutritional status, and the reclamation rate was negatively related with the salinity in the estuary. There was a significant positive correlation between the health status of the aquatic ecosystem and salinity, with a correlation coefficient of 0.93. The correlation coefficient between the health status and nutritional status was -0.71, while the correlation between the suspended matter concentration and health status was not as significant as that of the other two factors. The dynamics of the aquatic environment could be divided into four stages： sustainable health from the 1980s to the 1990s, continued deterioration from 2000 to 2003, improvement from 2004 to 2005, and secondary deterioration from 2006 to 2011. The Jiaojiang Estuary is faced with imminent environmental pressure at present.展开更多
Channel dredging in estuaries increases water depth and subsequently impacts sediment dynamics and morphology. The Jiaojiang River Estuary is dredged frequently owing to heavy shipping demands. In this study,the effec...Channel dredging in estuaries increases water depth and subsequently impacts sediment dynamics and morphology. The Jiaojiang River Estuary is dredged frequently owing to heavy shipping demands. In this study,the effects of different dredging schemes on siltation were assessed through numerical modeling. The sediment model of the Jiaojiang River Estuary utilized an optimized bottom boundary layer model that considered the bed sediment grain size and fluid mud, and this model was calibrated using field data. Result reveal that channel dredging modifies the flow velocity inside and around the channel by changing the bathymetry;subsequently, this affects the residual current, bed stress, suspended sediment concentration, and sediment fluxes. Increasing the dredging depth and width increases the net sediment fluxes into the channel and dredging depth has a greater influence on the channel siltation thickness. When the dredging depth is 8.4 m or11.4 m, the average siltation thickness of the channel is 0.07 m or 0.15 m per mouth respectively. The parallel movement of the channel has small effects on the siltation volume during the simulation period. The sediment deposits in the channel primarily originates from the tidal flats, through bottom sediment fluxes. Vertical net circulation has a dominant impact on siltation because the difference of horizontal current of each layer on the longitudinal section of the channel increases, which intensifies the lateral sediment transport between the shoal and channel. The influence of vertical frictional dissipation on the lateral circulation at the feature points accounts for more than 50% before dredging, while the non-linear advective term is dominant after dredging. Tidal pumping mainly affects the longitudinal sediment fluxes in the channel. These results can be used for channel management and planning for similar estuaries worldwide.展开更多
Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage,where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential.Utilizing geochemical ...Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage,where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential.Utilizing geochemical and basin modeling analysis,hydrocarbon generation capacity and process of the Paleocene E_(1)y,E_(1)l and E_(1)m formations were investigated.Results show that E_(1)y and E_(1)l mudstones are high-quality source rocks with Type Ⅱ kerogen,which is dominated by both aquatic organisms and terrestrial higher plants deposited in sub-reduced environment.E_(1)m mudstone interbedded with thin carbonaceous mudstone and coal is poor-quality source rock with Type Ⅲ kerogen,whose organic matter was originated from terrestrial higher plants under oxidized environment.Controlled by burial and maturity histories,E_(1)y and E_(1)l source rocks experienced two hydrocarbon generation stages,which took place in the Late Paleocene and in the Middle to Late Eocene,respectively,and had high hydrocarbon generation capacity with cumulative hydrocarbon volume of 363 and 328 mg/g,respectively.E_(1)m source rock only had one hydrocarbon generation process in the Late Eocene,which had low hydrocarbon generation capacity with cumulative hydrocarbon volume of only 24 mg/g.The future oil-gas exploration in the Jiaojiang sag should focus on hydrocarbon generation center and select targets in the central uplift formed before the Miocene with high-quality traps.展开更多
基金supported by National Basic Research Program of China (973) under grant No.2009CB219400
文摘An extensive suite of igneous sills was intruded into the Tertiary sedimentary section of the Jiaojiang sag, East China Sea. This suite has been well imaged offshore through 2D and 3D seismic surveys, showing a close relationship with CO2 content in nearby gas discoveries. A new observational model, which incorporates simple upward propagation, simple horizontal propagation, and transgressive propagation, was proposed to interpret these sill intrusions. In this model, the source magma of the saucer-shaped sills was injected from their lowest points near the center. The transgressive propagation can be interpreted as a combination of the vertical and horizontal propagation. Most shallow sub-volcanic intrusions in the Jiaojiang sag exhibit fingered characteristics, both vertically and horizontally. The vertical fingered propagation produced saucer-shaped sills arranged in the flower style. Along the brims of lower sills could usually be found the upper sills, which are interpreted to have formed simultaneously with or later than the lower feeder sills. In the second type, the chilled paths of the older sills were reutilized by subsequent intrusions. The horizontal fingered propagation formed sheet intrusions that exhibit groove, lobate, tubular, and crevasse splay- like geometry in plan view. In 3D view, the sheet intrusions have still preserved the lower center and higher rim that similar with the sub-rounded saucer-shaped sills. Although fracture propagation may be important, flow inflation was the key mechanism of magma intrusion. Further consideration of the mechanisms underlying sill formation may help explain the fingered characteristics of sill propagation.
基金supported by the National Nature Science Foundation of China(Grant No.40776007)Projects Founded by the Science and Technology Department of Zhejiang Province(Grant No.2009C03008-1)
文摘Variations in coastline geometry caused by coastal engineering affect tides, storm surges, and storm tides. Three cluster land reclamation projects have been planned for construction in the Jiaojiang Estuary during the period from 2011 to 2023. They will cause significant changes in coastline geometry. In this study, a surge-tide coupled model was established based on a three-dimensional finite-volume coastal ocean model （FVCOM）. A series of numerical experiments were carried out to investigate the effects of variations in coastline geometry on tides, storm surges, and storm tides. This model was calibrated using data observed at the Haimen and Ruian gauge stations and then used to reproduce the tides, storm surges, and storm tides in the Jiaojiang Estuary caused by Typhoon Winnie in 1997. Results show that the high tide level, peak storm surge, and high storm tide level at the Haimen Gauge Station increased along with the completion of reclamation projects, and the maximum increments caused by the third project were 0.13 m, 0.50 m, and 0.43 m, respectively. The envelopes with maximum storm tide levels of 7.0 m and 8.0 m inside the river mouth appeared to move seaward, with the latter shifting 1.8 km, 3.3 km, and 4.4 km due to the first project, second project, and third project, respectively. The results achieved in this study contribute to reducing the effects of, and preventing storm disasters after the land reclamation in the Jiaojiang Estuary.
基金supported by the Soft Science Research Project of the Zhejiang Association for Science and Technology(Grant No.KX12E-17)the Research Project of the Zhejiang Environmental Protection Bureau(Grant No.2012A033)
文摘A quantitative description of a long-term series of aquatic environmental factors and their spatial distributions was generated using measured data from the Jiaojiang Estuary from 1982 to 2011. The aquatic environmental factors included suspended matter, salinity, and nutrients. Based on these factors, the aquatic ecosystem health in the Jiaojiang Estuary over the last 30 years was analyzed. The results indicated that the suspended matter concentration in the estuary was mainly affected by the amounts of suspended sediment and solid waste, with the value fluctuating over a long period, and the range of high concentration expanded continually; the salinity was mainly affected by precipitation and surface water resources, showing an overall decreasing trend, and the region with low salinity moved seaward and toward the reclamation areas; and the nutritional status, mainly affected by discharge of industrial wastewater and domestic sewage, was satisfactory in the 1980s and 1990s, but the status became severe in recent years. Reclamation had a great influence on these three factors： high reclamation strength led to a significant increase in the suspended matter concentration and a deterioration of the nutritional status, and the reclamation rate was negatively related with the salinity in the estuary. There was a significant positive correlation between the health status of the aquatic ecosystem and salinity, with a correlation coefficient of 0.93. The correlation coefficient between the health status and nutritional status was -0.71, while the correlation between the suspended matter concentration and health status was not as significant as that of the other two factors. The dynamics of the aquatic environment could be divided into four stages： sustainable health from the 1980s to the 1990s, continued deterioration from 2000 to 2003, improvement from 2004 to 2005, and secondary deterioration from 2006 to 2011. The Jiaojiang Estuary is faced with imminent environmental pressure at present.
基金The National Key Research and Development Program of China under contract No. 2020YFD0900803the National Natural Science Foundation of China under contract Nos 41976157 and 42076177+1 种基金the Science Technology Department of Zhejiang Province under contract No. 2022C03044the State Key Laboratory of Satellite Ocean Environment Dynamics of the Ministry of Natural Resources of China under contract No. QNHX1807。
文摘Channel dredging in estuaries increases water depth and subsequently impacts sediment dynamics and morphology. The Jiaojiang River Estuary is dredged frequently owing to heavy shipping demands. In this study,the effects of different dredging schemes on siltation were assessed through numerical modeling. The sediment model of the Jiaojiang River Estuary utilized an optimized bottom boundary layer model that considered the bed sediment grain size and fluid mud, and this model was calibrated using field data. Result reveal that channel dredging modifies the flow velocity inside and around the channel by changing the bathymetry;subsequently, this affects the residual current, bed stress, suspended sediment concentration, and sediment fluxes. Increasing the dredging depth and width increases the net sediment fluxes into the channel and dredging depth has a greater influence on the channel siltation thickness. When the dredging depth is 8.4 m or11.4 m, the average siltation thickness of the channel is 0.07 m or 0.15 m per mouth respectively. The parallel movement of the channel has small effects on the siltation volume during the simulation period. The sediment deposits in the channel primarily originates from the tidal flats, through bottom sediment fluxes. Vertical net circulation has a dominant impact on siltation because the difference of horizontal current of each layer on the longitudinal section of the channel increases, which intensifies the lateral sediment transport between the shoal and channel. The influence of vertical frictional dissipation on the lateral circulation at the feature points accounts for more than 50% before dredging, while the non-linear advective term is dominant after dredging. Tidal pumping mainly affects the longitudinal sediment fluxes in the channel. These results can be used for channel management and planning for similar estuaries worldwide.
基金supported by the China National Science and Technology Major Project(Nos.2016ZX05024-002-003,2017ZX05032-001-004)the Foundation of Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education(China University of Geosciences),China(Nos.TPR-2022-11,TPR-2022-24)the Science and Technology Planning Project of Tangshan City,China(Nos.22130213H).
文摘Jiaojiang sag in the East China Sea Basin is at the earlier exploration stage,where characterizing hydrocarbon generation of source rocks is important to understand oil-gas exploration potential.Utilizing geochemical and basin modeling analysis,hydrocarbon generation capacity and process of the Paleocene E_(1)y,E_(1)l and E_(1)m formations were investigated.Results show that E_(1)y and E_(1)l mudstones are high-quality source rocks with Type Ⅱ kerogen,which is dominated by both aquatic organisms and terrestrial higher plants deposited in sub-reduced environment.E_(1)m mudstone interbedded with thin carbonaceous mudstone and coal is poor-quality source rock with Type Ⅲ kerogen,whose organic matter was originated from terrestrial higher plants under oxidized environment.Controlled by burial and maturity histories,E_(1)y and E_(1)l source rocks experienced two hydrocarbon generation stages,which took place in the Late Paleocene and in the Middle to Late Eocene,respectively,and had high hydrocarbon generation capacity with cumulative hydrocarbon volume of 363 and 328 mg/g,respectively.E_(1)m source rock only had one hydrocarbon generation process in the Late Eocene,which had low hydrocarbon generation capacity with cumulative hydrocarbon volume of only 24 mg/g.The future oil-gas exploration in the Jiaojiang sag should focus on hydrocarbon generation center and select targets in the central uplift formed before the Miocene with high-quality traps.
