Since the 1970s, remote sensing images have provided new information for the delineation and analysis of coastline changes, especially focusing on the short timescale changes. This paper, based on the Landsat MSS imag...Since the 1970s, remote sensing images have provided new information for the delineation and analysis of coastline changes, especially focusing on the short timescale changes. This paper, based on the Landsat MSS imagery, focuses on the coastline evolution of Yancheng, northern Jiangsu, China since the mid-Holocene. A zebra stripe image, which could reveal the ancient coastal evolution of Yancheng, was extracted from a Landsat MSS image. Based on the extracted black-white stripes, 19 surface sediment samples were recovered and analyzed to recognize the sedimentary characteristics of these stripes. It shows that most sand and silty sand samples appear on the white stripes, while silt and silty clay samples are on the black stripes. Sandy and muddy sediments present an alternating distri- bution pattern on the Yancheng coastal plain. A historical coastline map was drawn according to the previous research achievements of the paleo-coastal sand barriers and paleo-coastlines, and was superimposed on the zebra stripe image. The trend of the extracted zebra stripes is consistent with the historical coastlines, and it should be the symbol of the Yancheng coastline evolution. On the basis of ten sets of black-white stripes and previous research results, we divided the progression of Yancheng coastal evolution into three stages (i.e., the early stable stage (6500 a BP-AD 1128), the rapid deposition stage (AD 1128-1855) and the adjustment stage (AD 1855-present)). Ten sets of black-white stripes were identified as the characteristic pattern of the coastline evolution on the Yancheng coastal plain.展开更多
A behavior-oriented formula is improved to calculate the annual coastal bathymetry evolution caused by a reclamation work. This formula is based on a simple hypothesis that, on the time scale of years, the bathymetry ...A behavior-oriented formula is improved to calculate the annual coastal bathymetry evolution caused by a reclamation work. This formula is based on a simple hypothesis that, on the time scale of years, the bathymetry evolution is closely related to the change of tidal current field due to the reclamation work. A new coefficient,named the erosion reduction coefficient, is introduced to extend the original formula for applications in calculating bed erosion. A simplified relationship between the annual variation of the siltation/erosion rate and the water depth is introduced to more realistically represent the long-term process of the bathymetry evolution.The improved formula is applied to calculate the bathymetry evolution in 3 a following a reclamation project in the Xiaomiaohong Tidal Channel in Jiangsu coast in China. The results compare well with measurements and those obtained from a process-based numerical model, demonstrating the capability of the improved behaviororiented formula in reproducing the impact of the reclamation project on the local bathymetry evolution.展开更多
Paleoenvironmental reconstruction is fundamental to understand the modern environmental changes and to predict future environment, which is especially critical to understand the evolution of land and sea during geolog...Paleoenvironmental reconstruction is fundamental to understand the modern environmental changes and to predict future environment, which is especially critical to understand the evolution of land and sea during geological periods. However, the basic geological research on China's muddy coastal zone is not enough to provide quantitative data to compare with global changes. Therefore, in 2011, China Geological Survey deployed the "Late Quaternary geo-environmental evolution and modern process of China" project, and focused on the muddy coastal zones of the Liaodong Bay, Bohai Bay, the Yellow River Delta, Yangtze River Delta and Pearl River Delta (Fig. 1). Next we will briefly introduce our latest results in the Bohai Bay.展开更多
The Gabon Coastal Basin is a typical saliferous basin located in the middle portion of the West African passive continental margin. Complex salt tectonics make sedimentary sequences and structural frameworks difficult...The Gabon Coastal Basin is a typical saliferous basin located in the middle portion of the West African passive continental margin. Complex salt tectonics make sedimentary sequences and structural frameworks difficult to interpret and can lead to difficulties in construction of balanced cross-sections and reconstruction of basin evolutionary processes. Sedimentary facies and salt structur- al patterns displaying zonation are based on seismic reflection profiles and drilling data. Two near-vertical fault systems, NW-SE and NE-SW, caused basin to be subdivided E-W zoning and N-S partitioning. Scarp slopes and extension faults formed in the Hinge belt III zone where salt diapir piercement occurred and numbers of salt pillars, salt stocks and salt rollers developed under transten- sion of coupled near-orthogonal fault systems. The zone east of Hinge belt III is characterized by small-scale salt domes and salt pillows. To the west are large-scale salt walls and salt bulge anticlines caused by diapirism promoted by tension and torsion that also resulted in formation of numerous salt pillars, salt stocks and salt rollers. Our modeling of salt tectonic structures indicates that they were produced by plastic rheological deformation of salt under regional stress fields that varied during three distinct phases of extension, compression and re-activation. Hinge belt III was active from Coniacian to Early Eocene, which was a critical period of formation of salt structures when many extension-related salt structures formed and salt diapirism controlled the distribution of turbidite fans. Rootless extrusion-related salt stocks developed throughout the Late Eocene to Early Oligocene as a result of lo- cal ephemeral low-intensity tectonic inversion. Post Oligocene salt diapirism was weak and salt tecton- ics had a weak influence on sedimentation. Balanced cross-sections of two saliferous horizons crossing different tectonic units from east to west reveal that the basin tectonic evolution and sediment filling processes can be divided into three stages containing seven episodes of rifting, transition and drifting.展开更多
基金National Basic Research Program of China (973 Program), No.2010CB429001 Comprehensive Investigation and Assessment in Jiangsu Offshore Area, No.JS-908-01-02+4 种基金 National Key Technologies Research and Development Program of China, No.2012BAB03B00 Special Fund for Marine Scientific Research in the Public Interest, No.201005006-3 National Natural Science Foundation of China, No.51179067 Graduate Student Research and Innovation Project of Jiangsu General Higher Learning Institution, No.CXLX 12_0256 Natural Science Foundation of Jiangsu Province, No.BK2012414
文摘Since the 1970s, remote sensing images have provided new information for the delineation and analysis of coastline changes, especially focusing on the short timescale changes. This paper, based on the Landsat MSS imagery, focuses on the coastline evolution of Yancheng, northern Jiangsu, China since the mid-Holocene. A zebra stripe image, which could reveal the ancient coastal evolution of Yancheng, was extracted from a Landsat MSS image. Based on the extracted black-white stripes, 19 surface sediment samples were recovered and analyzed to recognize the sedimentary characteristics of these stripes. It shows that most sand and silty sand samples appear on the white stripes, while silt and silty clay samples are on the black stripes. Sandy and muddy sediments present an alternating distri- bution pattern on the Yancheng coastal plain. A historical coastline map was drawn according to the previous research achievements of the paleo-coastal sand barriers and paleo-coastlines, and was superimposed on the zebra stripe image. The trend of the extracted zebra stripes is consistent with the historical coastlines, and it should be the symbol of the Yancheng coastline evolution. On the basis of ten sets of black-white stripes and previous research results, we divided the progression of Yancheng coastal evolution into three stages (i.e., the early stable stage (6500 a BP-AD 1128), the rapid deposition stage (AD 1128-1855) and the adjustment stage (AD 1855-present)). Ten sets of black-white stripes were identified as the characteristic pattern of the coastline evolution on the Yancheng coastal plain.
基金The National Science Fund for Distinguished Young Scholars of China under contract No.51425901the Natural Science Foundation of Jiangsu Province of China under contract No.BK20161509+1 种基金the Fundamental Research Funds for the Central Universities of China under contract No.2015B15514the National Key Technology Research and Development Program of China under contract No.2012BAB03B01
文摘A behavior-oriented formula is improved to calculate the annual coastal bathymetry evolution caused by a reclamation work. This formula is based on a simple hypothesis that, on the time scale of years, the bathymetry evolution is closely related to the change of tidal current field due to the reclamation work. A new coefficient,named the erosion reduction coefficient, is introduced to extend the original formula for applications in calculating bed erosion. A simplified relationship between the annual variation of the siltation/erosion rate and the water depth is introduced to more realistically represent the long-term process of the bathymetry evolution.The improved formula is applied to calculate the bathymetry evolution in 3 a following a reclamation project in the Xiaomiaohong Tidal Channel in Jiangsu coast in China. The results compare well with measurements and those obtained from a process-based numerical model, demonstrating the capability of the improved behaviororiented formula in reproducing the impact of the reclamation project on the local bathymetry evolution.
基金funded by China Geological Survey(Grants No.1212011120169 and 12120113005800)the National Natural Science Foundation of China(Grants No.41206069,41476074 and 41372173)
文摘Paleoenvironmental reconstruction is fundamental to understand the modern environmental changes and to predict future environment, which is especially critical to understand the evolution of land and sea during geological periods. However, the basic geological research on China's muddy coastal zone is not enough to provide quantitative data to compare with global changes. Therefore, in 2011, China Geological Survey deployed the "Late Quaternary geo-environmental evolution and modern process of China" project, and focused on the muddy coastal zones of the Liaodong Bay, Bohai Bay, the Yellow River Delta, Yangtze River Delta and Pearl River Delta (Fig. 1). Next we will briefly introduce our latest results in the Bohai Bay.
基金supported by the National Natural Science Fundation of China(Nos.40839902 and 40739901)
文摘The Gabon Coastal Basin is a typical saliferous basin located in the middle portion of the West African passive continental margin. Complex salt tectonics make sedimentary sequences and structural frameworks difficult to interpret and can lead to difficulties in construction of balanced cross-sections and reconstruction of basin evolutionary processes. Sedimentary facies and salt structur- al patterns displaying zonation are based on seismic reflection profiles and drilling data. Two near-vertical fault systems, NW-SE and NE-SW, caused basin to be subdivided E-W zoning and N-S partitioning. Scarp slopes and extension faults formed in the Hinge belt III zone where salt diapir piercement occurred and numbers of salt pillars, salt stocks and salt rollers developed under transten- sion of coupled near-orthogonal fault systems. The zone east of Hinge belt III is characterized by small-scale salt domes and salt pillows. To the west are large-scale salt walls and salt bulge anticlines caused by diapirism promoted by tension and torsion that also resulted in formation of numerous salt pillars, salt stocks and salt rollers. Our modeling of salt tectonic structures indicates that they were produced by plastic rheological deformation of salt under regional stress fields that varied during three distinct phases of extension, compression and re-activation. Hinge belt III was active from Coniacian to Early Eocene, which was a critical period of formation of salt structures when many extension-related salt structures formed and salt diapirism controlled the distribution of turbidite fans. Rootless extrusion-related salt stocks developed throughout the Late Eocene to Early Oligocene as a result of lo- cal ephemeral low-intensity tectonic inversion. Post Oligocene salt diapirism was weak and salt tecton- ics had a weak influence on sedimentation. Balanced cross-sections of two saliferous horizons crossing different tectonic units from east to west reveal that the basin tectonic evolution and sediment filling processes can be divided into three stages containing seven episodes of rifting, transition and drifting.