The global rise in sea level during the Late Cretaceous has been an issue under discussion by the international geological community. Despite the signifi- cance, its impact on the deposition of continental basins is n...The global rise in sea level during the Late Cretaceous has been an issue under discussion by the international geological community. Despite the signifi- cance, its impact on the deposition of continental basins is not well known. This paper presents the systematic review on stratigraphy and sedimentary facies compiled from 22 continental basins in northern Africa. The results indicate that the region was dominated by sediments of continental facies during Early Cretaceous, which were replaced by deposits of marine facies in Late Cretaceous. The spatio- temporal distribution of sedimentary facies suggests marine facies deposition reached as far south as Taou- deni-Iullemmeden-Chad-A1 Kufra-Upper Egypt basins during Turonian to Campanian. These results indicate that northern Africa underwent significant transgression during Late Cretaceous reaching its peak during Turonian to Coniacian. This significant transgression has been attributed to the global high sea-level during this time. Previous studies show that global rise in sea level in Late Cretaceous may have been driven by an increase in the volume of ocean water （attributed to high C02 concentra- tion and subsequently warm climate） and a decrease in the volume of the ocean basin （attributed to rapid production of oceanic crust and seamounts）. Tectonic mechanism of rapid production of oceanic crust and seamounts could play a fimdamental role in driving the global rise in sea level and subsequent transgression in northern Africa during Late Cretaceous.展开更多
Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely popul...Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely populated and data-poor regions such as Northern Africa.The intensity and spatial distribution of nighttime lights provide useful information on human activities and can be observed by space-borne imaging radiometers.Our study helps to bridge the gap between the DMSP-OLS data available until 2013 and the NPP-VIIRS data available since 2013.The approach to calibrate the OLS data includes three steps:a)inter-calibrate the OLS DN data acquired by different sensors in 1992-2013;b)cali-brate the OLS DN data using VIIRS data in 2013;c)generate syn-thetic OLS radiance data by degrading the VIIRS data in 2013-2020.We generated a)a time series of calibrated OLS nighttime light radiance data(1992-2013);b)mean annual VIIRS radiance on stable lights at the OLS spatial resolution for 2013-2020;c)synthetic OLS radiance data generated using VIIRS radiance data degraded to match the radiometric specifications of OLS for 2013-2020.The evaluation of these data products in 2013 documented their accu-racy and consistency.展开更多
文摘The global rise in sea level during the Late Cretaceous has been an issue under discussion by the international geological community. Despite the signifi- cance, its impact on the deposition of continental basins is not well known. This paper presents the systematic review on stratigraphy and sedimentary facies compiled from 22 continental basins in northern Africa. The results indicate that the region was dominated by sediments of continental facies during Early Cretaceous, which were replaced by deposits of marine facies in Late Cretaceous. The spatio- temporal distribution of sedimentary facies suggests marine facies deposition reached as far south as Taou- deni-Iullemmeden-Chad-A1 Kufra-Upper Egypt basins during Turonian to Campanian. These results indicate that northern Africa underwent significant transgression during Late Cretaceous reaching its peak during Turonian to Coniacian. This significant transgression has been attributed to the global high sea-level during this time. Previous studies show that global rise in sea level in Late Cretaceous may have been driven by an increase in the volume of ocean water （attributed to high C02 concentra- tion and subsequently warm climate） and a decrease in the volume of the ocean basin （attributed to rapid production of oceanic crust and seamounts）. Tectonic mechanism of rapid production of oceanic crust and seamounts could play a fimdamental role in driving the global rise in sea level and subsequent transgression in northern Africa during Late Cretaceous.
基金supported by the National Natural Science Foundation of China project(Grant No.41661144022)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA19030203),the Chinese Academy of Sciences President’s International Fellowship Initiative(Grant No.2020VTA0001),and the MOST High-Level Foreign Expert program(Grant No.GL20200161002).
文摘Human activities modulate the impact of environmental forcing in general and of climate in particular.Information on the spatial and temporal patterns of human activities is in high demand,but scarce in sparsely populated and data-poor regions such as Northern Africa.The intensity and spatial distribution of nighttime lights provide useful information on human activities and can be observed by space-borne imaging radiometers.Our study helps to bridge the gap between the DMSP-OLS data available until 2013 and the NPP-VIIRS data available since 2013.The approach to calibrate the OLS data includes three steps:a)inter-calibrate the OLS DN data acquired by different sensors in 1992-2013;b)cali-brate the OLS DN data using VIIRS data in 2013;c)generate syn-thetic OLS radiance data by degrading the VIIRS data in 2013-2020.We generated a)a time series of calibrated OLS nighttime light radiance data(1992-2013);b)mean annual VIIRS radiance on stable lights at the OLS spatial resolution for 2013-2020;c)synthetic OLS radiance data generated using VIIRS radiance data degraded to match the radiometric specifications of OLS for 2013-2020.The evaluation of these data products in 2013 documented their accu-racy and consistency.
