Geodetic measurements of a Roman aqueduct in Caesarea,on the Mediterranean coast of central Israel,show that the massive structure preserved its original gradient of 0.05%in places where it was founded on rock,suggest...Geodetic measurements of a Roman aqueduct in Caesarea,on the Mediterranean coast of central Israel,show that the massive structure preserved its original gradient of 0.05%in places where it was founded on rock,suggesting that that domain has been tectonically stable for the last two millennia.Consequently,since the land was stable,dated archaeological sealevel proxies that recorded their contemporaneous sealevels when the city was active,reflect global sealevel and their variations.The evidence suggests that sealevel was similar to the present some 2,000 years ago,it was nearly 0.5 m higher than the present some 1,300 years ago,and about 0.5 m lower nearly 800 years ago.These measurements match earlier climatological evidence of the early Mediaeval Warm Period and the early stages of the Little Ice Age,respectively.No sealevel evidence was encountered in Caesarea after the collapse of the Crusaders’kingdom.展开更多
The platform-facies carbonate rocks of the Carboniferous-Permian boundary strata are well developed and outcropped in Xikou （西口）, Zhen＇an （镇安） County, Shaanxi （ 陕西 ） Province, China. The carbonate diagenc...The platform-facies carbonate rocks of the Carboniferous-Permian boundary strata are well developed and outcropped in Xikou （西口）, Zhen＇an （镇安） County, Shaanxi （ 陕西 ） Province, China. The carbonate diagencsis in the Carboniferous-Permian boundary section at Xikou contains many processes with conspicuous effects, including micritization, cementation, mechanical and chemical compaction, neomorphism, and dissolution. Based on mineralogical composition and microfabrics, the diagenetic environments are distinguished into marine, near surface meteoric and burial environments. Detailed petrographical observation of abundant thin sections integrated with previous studies on sequence stratigraphy reveals that the carbonate diagenesis in the Carboniferous-Permian boundary section is related to the relative stratigraphic position of the rocks in the high-frequency cycles and controlled by the glacioeustatic sea-level changes. There are distinctive differences in diagenetic patterns between the lower transgressive sequence and the upper regressive sequence in a cyclothem. The diagenesis in the lower transgressive sequence is mainly characterized by pressure dissolution and recrystallization of mudstone and wackstone in a burial environment, and the diagenesis in the upper regressive sequence by cementation and leaching of freshwater in a meteoric environment.展开更多
The upper ocean currents in the Pacific Ocean are calculated by using an ocean model with higher horizontal resolution. The large current systems in the Pacific Ocean, such as Kuroshio, Oyashio, NEC, SEC, NECC,Califom...The upper ocean currents in the Pacific Ocean are calculated by using an ocean model with higher horizontal resolution. The large current systems in the Pacific Ocean, such as Kuroshio, Oyashio, NEC, SEC, NECC,Califomia Current and East Australia Current, are well simulated. This paper only gives the numerical simulation results of the upper ocean currents of the representative months in four seasons in the South China Sea (SCS). It showsthat the SCS branch of Kuroshio is the most important current in the northem SCS and it is not only the water resourceof the SCS warm current but also a significant part of the overall SCS circulation. There is a relatively strong northeastward flow entering the SCS through the Taiwan Strait throughout the year except for specific months. Some of thenumerical results have been confirmed by the observational evidences.展开更多
文摘Geodetic measurements of a Roman aqueduct in Caesarea,on the Mediterranean coast of central Israel,show that the massive structure preserved its original gradient of 0.05%in places where it was founded on rock,suggesting that that domain has been tectonically stable for the last two millennia.Consequently,since the land was stable,dated archaeological sealevel proxies that recorded their contemporaneous sealevels when the city was active,reflect global sealevel and their variations.The evidence suggests that sealevel was similar to the present some 2,000 years ago,it was nearly 0.5 m higher than the present some 1,300 years ago,and about 0.5 m lower nearly 800 years ago.These measurements match earlier climatological evidence of the early Mediaeval Warm Period and the early stages of the Little Ice Age,respectively.No sealevel evidence was encountered in Caesarea after the collapse of the Crusaders’kingdom.
基金This paper is financially supported by the National Natural ScienceFoundation of China (No .40172014)the Chinese Academy of Sciences(No . KZCX3-SW-143)the Ministry of Science and Technology ofChina (No .2002CB412602) .
文摘The platform-facies carbonate rocks of the Carboniferous-Permian boundary strata are well developed and outcropped in Xikou （西口）, Zhen＇an （镇安） County, Shaanxi （ 陕西 ） Province, China. The carbonate diagencsis in the Carboniferous-Permian boundary section at Xikou contains many processes with conspicuous effects, including micritization, cementation, mechanical and chemical compaction, neomorphism, and dissolution. Based on mineralogical composition and microfabrics, the diagenetic environments are distinguished into marine, near surface meteoric and burial environments. Detailed petrographical observation of abundant thin sections integrated with previous studies on sequence stratigraphy reveals that the carbonate diagenesis in the Carboniferous-Permian boundary section is related to the relative stratigraphic position of the rocks in the high-frequency cycles and controlled by the glacioeustatic sea-level changes. There are distinctive differences in diagenetic patterns between the lower transgressive sequence and the upper regressive sequence in a cyclothem. The diagenesis in the lower transgressive sequence is mainly characterized by pressure dissolution and recrystallization of mudstone and wackstone in a burial environment, and the diagenesis in the upper regressive sequence by cementation and leaching of freshwater in a meteoric environment.
文摘The upper ocean currents in the Pacific Ocean are calculated by using an ocean model with higher horizontal resolution. The large current systems in the Pacific Ocean, such as Kuroshio, Oyashio, NEC, SEC, NECC,Califomia Current and East Australia Current, are well simulated. This paper only gives the numerical simulation results of the upper ocean currents of the representative months in four seasons in the South China Sea (SCS). It showsthat the SCS branch of Kuroshio is the most important current in the northem SCS and it is not only the water resourceof the SCS warm current but also a significant part of the overall SCS circulation. There is a relatively strong northeastward flow entering the SCS through the Taiwan Strait throughout the year except for specific months. Some of thenumerical results have been confirmed by the observational evidences.
