Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope...Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope Stage （MIS） 3 by a combination of Accelerator Mass Spectrometric （AMS） carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus （IRD） events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian Arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Mostδ18O andδ13C values of Neogloboquadrina pachyderma （sinistral） （Nps） in Core 08P23 are lighter than the average values of surface sediments. The lighterδ18O andδ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. Theδ18O values varied inversely withδ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values ofδ18O andδ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.展开更多
Theoretical analysis and numerical simulation have been applied to researching the effect of wave,current and wind on the ice rafting.The analytical results show that wave is the key factor for ice fracture.The proces...Theoretical analysis and numerical simulation have been applied to researching the effect of wave,current and wind on the ice rafting.The analytical results show that wave is the key factor for ice fracture.The process of ice rafting is simulated using the discrete element method.The simulated results show that the distortion or flexure breakage happens firstly,then followed by ice rafting.The comprehensively analysed results show that the ice is easily rafted on the simultaneity action of wave,current and wind,and the action of wave can＇t be ignored.Moreover,the rafted ice length increases with the enhancive force of ocean current and wind.展开更多
The gradual increase in shipping and drilling activities in the Arctic regions has resulted in the increased importance of studying the structural safety of polar ships in various ice conditions.Rafted ice refers to a...The gradual increase in shipping and drilling activities in the Arctic regions has resulted in the increased importance of studying the structural safety of polar ships in various ice conditions.Rafted ice refers to a type of accumulated and overlapped sea ice;it is driven by external forces,such as wind and waves,and may exert high loads on ships and threaten their structural safety.Therefore,the properties of rafted ice and the construction of numerical models should be studied before exploring the interaction and collision between ships and rafted ice.Based on the nonlinear finite-element method,this paper introduces the cohesive element model for the simulation of rafted ice.The interaction between ships and rafted ice is studied,and the ice force of the hull is obtained.Numerical simulation results are compared with model test findings,and the effectiveness of the cohesive element method in the construction of the model of rafted ice materials is verified.On this basis,a multilayer rafted ice model is constructed,and its interaction with the ship is studied.The research unveils that rafted ice parts impede crack generation and slow down crack propagation to a certain extent.展开更多
基金The National Natural Science Foundation of China under contract Nos 41030859,41211120173,CHINARE2015-03-02 and IC201105the Geological Investigation Project of China Geological Survey Nos 12120113006200 and 1212011120044
文摘Multiproxy investigations have been performed on Core 08P23 collected from the Chukchi Plateau, the western Arctic Ocean, during the Third Chinese National Arctic Expedition. The core was dated back to Ma-rine Isotope Stage （MIS） 3 by a combination of Accelerator Mass Spectrometric （AMS） carbon-14 dating and regional core correlation. A total of five prominent ice-rafted detritus （IRD） events were recognized in MIS 2 and MIS 3. The IRD sources in MIS 3 are originated from vast carbonate rock outcrops of the Canadian Arctic Archipelago and clastic quartz in MIS 2 may have a Eurasian origin. Mostδ18O andδ13C values of Neogloboquadrina pachyderma （sinistral） （Nps） in Core 08P23 are lighter than the average values of surface sediments. The lighterδ18O andδ13C values of Nps in the two brown layers in MIS 1 and MIS 3 were resulted from meltwater events; and those in the gray layers in MIS 3 were caused by the enhanced sea ice formation. Theδ18O values varied inversely withδ13C in MIS 2 indicate that the study area was covered by thick sea ice or ice sheet with low temperature and little meltwater, which prevented the biological productivity and sea-atmosphere exchange, as well as water mass ventilation. The covaried light values ofδ18O andδ13C in MIS 1 and MIS 3 were resulted from meltwater and/or brine injection.
基金The National Natural Science Foundation of China under contract Nos 40506009 and 908-02-03’ National Project
文摘Theoretical analysis and numerical simulation have been applied to researching the effect of wave,current and wind on the ice rafting.The analytical results show that wave is the key factor for ice fracture.The process of ice rafting is simulated using the discrete element method.The simulated results show that the distortion or flexure breakage happens firstly,then followed by ice rafting.The comprehensively analysed results show that the ice is easily rafted on the simultaneity action of wave,current and wind,and the action of wave can＇t be ignored.Moreover,the rafted ice length increases with the enhancive force of ocean current and wind.
基金The National Natural Science Foundation of China(Grant Nos.52192693,52192690,51979051,51979056 and U20A20327)the National Key Research and Development Program of China(Grant No.2021YFC2803400)。
文摘The gradual increase in shipping and drilling activities in the Arctic regions has resulted in the increased importance of studying the structural safety of polar ships in various ice conditions.Rafted ice refers to a type of accumulated and overlapped sea ice;it is driven by external forces,such as wind and waves,and may exert high loads on ships and threaten their structural safety.Therefore,the properties of rafted ice and the construction of numerical models should be studied before exploring the interaction and collision between ships and rafted ice.Based on the nonlinear finite-element method,this paper introduces the cohesive element model for the simulation of rafted ice.The interaction between ships and rafted ice is studied,and the ice force of the hull is obtained.Numerical simulation results are compared with model test findings,and the effectiveness of the cohesive element method in the construction of the model of rafted ice materials is verified.On this basis,a multilayer rafted ice model is constructed,and its interaction with the ship is studied.The research unveils that rafted ice parts impede crack generation and slow down crack propagation to a certain extent.
