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Paleosalinity reconstruction in offshore lacustrine basins based on elemental geochemistry:a case study of Middle Upper Eocene Shahejie Formation,Zhanhua Sag,Bohai Bay Basin
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作者 Long SUN Shenghe WU +1 位作者 Dali YUE wenfu cui 《Journal of Oceanology and Limnology》 SCIE CAS CSCD 2024年第4期1087-1105,共19页
Salinity is a crucial property of water body and is essential for the restoration of paleoecology and paleoenvironment.However,the theoretical method of application of elemental geochemical proxies to paleosalinity re... Salinity is a crucial property of water body and is essential for the restoration of paleoecology and paleoenvironment.However,the theoretical method of application of elemental geochemical proxies to paleosalinity reconstruction is still underdeveloped.Moreover,accurate determination and reconstruction of paleosalinity and its variation in an offshore lacustrine basin have been extremely challenging thus far.This study presents detailed elemental geochemical investigations from the Zhanhua Sag in the southern Bohai Bay Basin to reconstruct the salinity variation in the Paleogene Eocene Shahejie Formation(50.8-33.9 Ma).Based on the variation of strontium barium ratio(Sr/Ba)and boron gallium ratio(B/Ga),we determined three typical salinity types of water body:salty water(Sr/Ba>0.5,B/Ga>6),brackish water(0.2<Sr/Ba<0.5,3<B/Ga<6),and fresh water(Sr/Ba<0.2,B/Ga<3),after eliminating carbonate-sourced strontium(Sr).The salinity values following Couch’s paleosalinometer r anged from 3.1 to 11.9,reflecting the overall characteristics of oligohaline(0.5<salinity value<5)to mesohaline(5<salinity value<18)brackish water.All proxies yielded similar trends in paleosalinity variation,demonstrating a clear trend of rising and then declining from 50.8 Ma to 33.9 Ma.We considered that the B/Ga ratio had the highest reliability and resolution in determining the salinity types of water body in the study area.The environmental factors causing paleosalinity variation were also thoroughly analysed based on the temporal relationship among the salinity types of watermasses,paleoclimate characteristics from pollen records,and marine transgression events from marine fossils.Our research established a model of paleoclimatic and eustatic mechanisms to explain paleosalinity variation,providing reasonable and integral driving forces for the salinity variation of all offshore lacustrine basins. 展开更多
关键词 PALEOSALINITY PALEOCLIMATE Zhanhua Sag Middle-Upper Eocene Shahejie Formation
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Effect of Surface Texture on Tensile Shear Strength of 1060Al-PET Welding Joints 被引量:1
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作者 Jia Liu Yuchi Dai +2 位作者 Yan Shi wenfu cui Tao Jiang 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2021年第5期306-321,共16页
Joining metal to plastic can lighten weight of products to reduce energy consumption.However,it is difficult to achieve high-strength welding between metal and plastic.To address this problem,the methods of surface te... Joining metal to plastic can lighten weight of products to reduce energy consumption.However,it is difficult to achieve high-strength welding between metal and plastic.To address this problem,the methods of surface texture pretreatment and laser irradiation welding was proposed to achieve the high-strength connection of metal and plastic.In this study,with different parameters of laser power and texture morphology,1060 Al with surface texture treatment was joined to polyethylene terephthalate(PET)by laser irradiation welding from metal side.Study showed that as the laser power increased,the tensile shear strength of joints increased first,and decreased thereafter.Tensile shear tests demonstrated that the mechanical force of joint was strengthened contributed to mechanical anchorage formed by surface texture.The depth-width ratio of the texture grooves affected the tensile shear process of the joint.According to the result of temperature simulation,the existence of texture grooves reduced the heat transfer efficiency,and the heat dissipation at interface was also impeded in course of laser welding.Finally,the maximum tensile strength of 1060Al-PET joint reached 48.4 MPa,which was close to the strength of PET matrix.The bonding mechanism of the 1060Al-PET joints was composed of mechanical bonding and chemical bonding.This study proposes an effective method to join metal to plastic which achieved high-strength connection between metal and plastic. 展开更多
关键词 1060Al-PET Surface texture Tensile shear strength Depth/width ratio Mechanical anchoring effect
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