以往针对南海北部陆架沉积物物质来源的诸多研究，在一定程度上忽略了海南岛物质的影响。基于柱状沉积物样品的岩性、粒度、粘土矿物和 AMS14 C 年代分析，探讨了琼东南陆架沉积区 X2站沉积物的物质来源。结果表明，X2站沉积物可划分为...以往针对南海北部陆架沉积物物质来源的诸多研究，在一定程度上忽略了海南岛物质的影响。基于柱状沉积物样品的岩性、粒度、粘土矿物和 AMS14 C 年代分析，探讨了琼东南陆架沉积区 X2站沉积物的物质来源。结果表明，X2站沉积物可划分为上、下两段，下段（Ⅰ，240-120 cm）主要为粘土质粉砂，上段（Ⅱ，120-0 cm）主要为粉砂质砂。粘土矿物主要由伊利石和高岭石组成，含有少量绿泥石和蒙脱石。对比分析显示，伊利石和绿泥石可能主要来自于珠江和台湾岛；高岭石可能主要来源于海南岛和珠江，蒙脱石主要来自于近源的雷琼地区，即海南岛物源对南海北部陆架西段具有一定的影响。近4 ka 以来，X2站沉积物的明显变粗和高岭石含量逐渐增高，说明海南物质的输入增强，这可能是由于近4 ka 以来的气候变化或者人类活动增强所致。展开更多
Based on the measured data in recent 20 years, the variation trends of the median grain size of the surface sediment, the sand-silt boundary and the mud area on the adjacent continental shelf of the Yangtze Estuary we...Based on the measured data in recent 20 years, the variation trends of the median grain size of the surface sediment, the sand-silt boundary and the mud area on the adjacent continental shelf of the Yangtze Estuary were analyzed in depth, and the effects of natural mechanism and human activities were discussed. The results show that： （1） In recent years （2006-2013）, the median grain size of sediment and the distribution pattern of grouped sediments in the adjacent continental shelf area to the Yangtze Estuary have presented no obvious change compared with those before 2006; （2） The median diameter of the surface sediment in the continental shelf area displayed a coarsening trend with the decrease of sediment discharge from the basin and the drop in suspended sediment concentration in the shore area; （3） In 2004-2007, the sand-silt boundary in the north part （31 ~30＇N） of the continental shelf area presented no significant changes, while that in the south part （31~30＇S） moved inwards; In 2008-2013, both the sand-silt boundaries in the north and south parts of the continental shelf area moved inwards, mainly due to the fact that in the dry season, a relatively enhanced hydrodynamic force of the tides was generated in the Yangtze River, as well as a decreased suspended sediment concentration and a flow along the banks in North Jiangsu; （4） The mud area where the maximum deposition rate is found in the Yangtze Estuary, tends to shrink due to the drop in sediment discharge from the basin, and the decrease in suspended sediment concentration in the shore area and erosion in the delta. Moreover, it tended to shift to the south at the same time because the implement of the training works on the deep-water channel of the North Passage changed the split ratio between the North and South Passages with an increase in the power of the discharged runoff in the South Passage.展开更多
The frequent upwarping and subsidence,and folding and uplifting of the earth crust caused by the isostatic adjustments and tectonic movements change the types of sediments in the basins frequently,and often cause the ...The frequent upwarping and subsidence,and folding and uplifting of the earth crust caused by the isostatic adjustments and tectonic movements change the types of sediments in the basins frequently,and often cause the occurrence of multi-source formations in the geologic profile.As in the Tarim basin,during the first transgression in the early paleozoic,the deepest location was the Ordovician sag,in which deep marine clastic and carbonate rocks were deposited and main source rocks were included.In the late Paleozoic,it was the second transgression cycle,the thickest sedi-ments of Carboniferous-Permian were deposited in thie Awati sag and southwest sag which would be another major petroleum source rocks(Fig.2).展开更多
Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in t...Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions.The first,the sediment load/yield of the islands has the same pattern as the adjacent small,mountainous rivers along the coastline;and the second,each of the islands was treated as a single catchment.The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a,which is comparable to the supply from the local smaller rivers.A sensitivity analysis indicates that this value represents the lower limit of estimate;if the accurate amount of sub-catchments of any island is considered,then this value will be enhanced slightly.This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and,therefore,should be paid with attention.展开更多
文摘以往针对南海北部陆架沉积物物质来源的诸多研究，在一定程度上忽略了海南岛物质的影响。基于柱状沉积物样品的岩性、粒度、粘土矿物和 AMS14 C 年代分析，探讨了琼东南陆架沉积区 X2站沉积物的物质来源。结果表明，X2站沉积物可划分为上、下两段，下段（Ⅰ，240-120 cm）主要为粘土质粉砂，上段（Ⅱ，120-0 cm）主要为粉砂质砂。粘土矿物主要由伊利石和高岭石组成，含有少量绿泥石和蒙脱石。对比分析显示，伊利石和绿泥石可能主要来自于珠江和台湾岛；高岭石可能主要来源于海南岛和珠江，蒙脱石主要来自于近源的雷琼地区，即海南岛物源对南海北部陆架西段具有一定的影响。近4 ka 以来，X2站沉积物的明显变粗和高岭石含量逐渐增高，说明海南物质的输入增强，这可能是由于近4 ka 以来的气候变化或者人类活动增强所致。
基金supported by the Fundamental Research Funds for Central Welfare Research Institutes(Grant No.TKS160103)the National Key Research and Development Program of China(Grant No.2016YFC0402106)the National Natural Science Foundation of China(Grant Nos.51579123 and 41331174)
文摘Based on the measured data in recent 20 years, the variation trends of the median grain size of the surface sediment, the sand-silt boundary and the mud area on the adjacent continental shelf of the Yangtze Estuary were analyzed in depth, and the effects of natural mechanism and human activities were discussed. The results show that： （1） In recent years （2006-2013）, the median grain size of sediment and the distribution pattern of grouped sediments in the adjacent continental shelf area to the Yangtze Estuary have presented no obvious change compared with those before 2006; （2） The median diameter of the surface sediment in the continental shelf area displayed a coarsening trend with the decrease of sediment discharge from the basin and the drop in suspended sediment concentration in the shore area; （3） In 2004-2007, the sand-silt boundary in the north part （31 ~30＇N） of the continental shelf area presented no significant changes, while that in the south part （31~30＇S） moved inwards; In 2008-2013, both the sand-silt boundaries in the north and south parts of the continental shelf area moved inwards, mainly due to the fact that in the dry season, a relatively enhanced hydrodynamic force of the tides was generated in the Yangtze River, as well as a decreased suspended sediment concentration and a flow along the banks in North Jiangsu; （4） The mud area where the maximum deposition rate is found in the Yangtze Estuary, tends to shrink due to the drop in sediment discharge from the basin, and the decrease in suspended sediment concentration in the shore area and erosion in the delta. Moreover, it tended to shift to the south at the same time because the implement of the training works on the deep-water channel of the North Passage changed the split ratio between the North and South Passages with an increase in the power of the discharged runoff in the South Passage.
文摘The frequent upwarping and subsidence,and folding and uplifting of the earth crust caused by the isostatic adjustments and tectonic movements change the types of sediments in the basins frequently,and often cause the occurrence of multi-source formations in the geologic profile.As in the Tarim basin,during the first transgression in the early paleozoic,the deepest location was the Ordovician sag,in which deep marine clastic and carbonate rocks were deposited and main source rocks were included.In the late Paleozoic,it was the second transgression cycle,the thickest sedi-ments of Carboniferous-Permian were deposited in thie Awati sag and southwest sag which would be another major petroleum source rocks(Fig.2).
基金Supported by the National Natural Science Foundation of China(Nos.41625021,41876092,41576095,41906021)。
文摘Continental shelf islands are contributors of terrestrial sediment supply to shelf regions,and the sediment flux from these islands shall be quantified.We calculated the sediment flux of continental shelf islands in the southeastern China using two empirical equations under two preconditions.The first,the sediment load/yield of the islands has the same pattern as the adjacent small,mountainous rivers along the coastline;and the second,each of the islands was treated as a single catchment.The results show that the sediment supply from these islands reached an order of magnitude of 1 Mt/a,which is comparable to the supply from the local smaller rivers.A sensitivity analysis indicates that this value represents the lower limit of estimate;if the accurate amount of sub-catchments of any island is considered,then this value will be enhanced slightly.This study demonstrates that the sediment supply from continental shelf islands to oceans is an important factor affecting the regional sedimentation and,therefore,should be paid with attention.
