The Luonan Basin is a key region of early human settlement in Central China with more than 300 discovered Paleolithic sites. Artifact layer 1 of the Liuwan site was dated to approximately 0.6 million years (Ma) based ...The Luonan Basin is a key region of early human settlement in Central China with more than 300 discovered Paleolithic sites. Artifact layer 1 of the Liuwan site was dated to approximately 0.6 million years (Ma) based on correlation with the well-dated loess-paleosol sequence of the central Chinese Loess Plateau. This study reassessed the age of the Liuwan artifact layer via an absolute dating method, namely, <sup>26</sup>Al/<sup>10</sup>Be burial dating. We determined the burial age of artifact layer 1, which was most likely at least 0.60 ± 0.12 Ma (1ơ), using three simple burial ages. The new burial age confirmed the previous estimated age and provided a considerably accurate age range. Therefore, we suggest the use of the <sup>26</sup>Al/<sup>10</sup>Be burial dating method in thin loess-covered Paleolithic sites around the Qinling Mountain Range is helpful to understand the early human behavior.展开更多
The onset of Quaternary glaciations is a critical event in the climate and tectonic history of the Tibetan Plateau.The Shishapangma Glaciation,defined based on the till deposit from the northern slopes of Mt.Shishapan...The onset of Quaternary glaciations is a critical event in the climate and tectonic history of the Tibetan Plateau.The Shishapangma Glaciation,defined based on the till deposit from the northern slopes of Mt.Shishapangma,has been identified as the oldest glaciation on the Tibetan Plateau.However,the timing of this glaciation has not been constrained.We measured^(10)Be and^(26)Al concentrations of a set of boulders on top of this till and simulated their complex exposure-burial histories.The simulated results indicate that the formation age of this till is likely around 835.2±241.0 ka,representing the minimum timing of glacial onset on the Tibetan Plateau.The Shishapangma Glaciation is apparently much younger than the glacial onset in many other areas of the world,such as Europe and North America,and was likely driven by the coupled effect between tectonic uplift and climate cooling during the early–middle Pleistocene transition.展开更多
Topographic shielding(TS) is an important factor in cosmogenic nuclide surface exposure dating. The development of geographic information systems(GIS) and the availability of digital elevation models(DEMs) make it pos...Topographic shielding(TS) is an important factor in cosmogenic nuclide surface exposure dating. The development of geographic information systems(GIS) and the availability of digital elevation models(DEMs) make it possible to derive this factor directly from a DEM. Most available GIS models derive the TS factors for an area(all cells in a DEM) without the consideration of surface conditions of individual sites, such as the strike, dip,and height above ground, into the calculation. This paper presents a new GIS model to derive the TS factors for discrete sample sites. This model uses the Skyline and Skyline Graph functions in ArcGIS to extract the set of azimuth and elevation angles of topographic obstructions around each site from a DEM(considering the sample height above ground)and then incorporates the strike and dip information of the sample surface to derive the TS factor. All processing tools and steps are streamlined in ArcGIS modelbuilder and this model can be run like a standard ArcGIS geoprocessing tool. It provides an easy and user-friendly means to derive the TS factors for discrete samples based on a DEM and the measured strike, dip and sample height for each site.展开更多
基金National Natural Science Foundation of China,No.41572155,No.41690111The Global Change Program of the Ministry of Science and Technology of China,No.2016YFA0600503
文摘The Luonan Basin is a key region of early human settlement in Central China with more than 300 discovered Paleolithic sites. Artifact layer 1 of the Liuwan site was dated to approximately 0.6 million years (Ma) based on correlation with the well-dated loess-paleosol sequence of the central Chinese Loess Plateau. This study reassessed the age of the Liuwan artifact layer via an absolute dating method, namely, <sup>26</sup>Al/<sup>10</sup>Be burial dating. We determined the burial age of artifact layer 1, which was most likely at least 0.60 ± 0.12 Ma (1ơ), using three simple burial ages. The new burial age confirmed the previous estimated age and provided a considerably accurate age range. Therefore, we suggest the use of the <sup>26</sup>Al/<sup>10</sup>Be burial dating method in thin loess-covered Paleolithic sites around the Qinling Mountain Range is helpful to understand the early human behavior.
基金supported by the National Natural Science Foundation of China(41101003,41230743,41328001,and 41371082)National Natural Science Awards of China(2009) to Yafeng Shi,Zhijiu Cui,Jijun Li,Benxing Zheng,and Shangzhe Zhou(Z104-2-05)
文摘The onset of Quaternary glaciations is a critical event in the climate and tectonic history of the Tibetan Plateau.The Shishapangma Glaciation,defined based on the till deposit from the northern slopes of Mt.Shishapangma,has been identified as the oldest glaciation on the Tibetan Plateau.However,the timing of this glaciation has not been constrained.We measured^(10)Be and^(26)Al concentrations of a set of boulders on top of this till and simulated their complex exposure-burial histories.The simulated results indicate that the formation age of this till is likely around 835.2±241.0 ka,representing the minimum timing of glacial onset on the Tibetan Plateau.The Shishapangma Glaciation is apparently much younger than the glacial onset in many other areas of the world,such as Europe and North America,and was likely driven by the coupled effect between tectonic uplift and climate cooling during the early–middle Pleistocene transition.
基金support by the National Science Foundation of the United States(Grant No.BCS-1227018)the National Nature Science Foundation of China(Grant No.41328001)
文摘Topographic shielding(TS) is an important factor in cosmogenic nuclide surface exposure dating. The development of geographic information systems(GIS) and the availability of digital elevation models(DEMs) make it possible to derive this factor directly from a DEM. Most available GIS models derive the TS factors for an area(all cells in a DEM) without the consideration of surface conditions of individual sites, such as the strike, dip,and height above ground, into the calculation. This paper presents a new GIS model to derive the TS factors for discrete sample sites. This model uses the Skyline and Skyline Graph functions in ArcGIS to extract the set of azimuth and elevation angles of topographic obstructions around each site from a DEM(considering the sample height above ground)and then incorporates the strike and dip information of the sample surface to derive the TS factor. All processing tools and steps are streamlined in ArcGIS modelbuilder and this model can be run like a standard ArcGIS geoprocessing tool. It provides an easy and user-friendly means to derive the TS factors for discrete samples based on a DEM and the measured strike, dip and sample height for each site.
