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Cai M.,Capital Normal University | Cai M.,Key Laboratory of Resource Environment and Geographic Information System | Cai M.,State Key Laboratory Cultivation Base Urban Environment Process and Digital Module | Cai M.,CAS Institute of Geographical Sciences and Natural Resources Research | And 12 more authors.
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2015

Beijing is of great significance in human evolution studies. However, the lack of well-dated records of climate and environmental changes, which are frequently cited as important drivers of early human evolution, impede understanding of the evolution and dispersal of humans on the Beijing plain. A 150-m deep drill core was collected from the Changping District of the Beijing plain to reconstruct the changes in vegetation and climate during the Middle Pleistocene using pollen records. The results indicated that the tree genus Ulmus and the herb genus Artemisia were dominant in most of the samples from 0.96 to 0.61 Ma, reflecting an open forest steppe covering the Beijing region. Between 0.61 and 0.44 Ma, the vegetation communities shifted to an Artemisia-steppe as the tree cover declined. This was followed by a further shift in vegetation community structure to a Chenopodiaceae-Asteraceae steppe between 0.44 and 0.23 Ma, followed by the conversion to an Artemisia-Asteraceae steppe after 0.23 Ma. The pollen record revealed a long-term deterioration of the vegetation, which indicated an increasing trend of drying and cooling in the Beijing plain during the Middle Pleistocene. This coincides with the Homo erectus colonization of North China during this period. These findings provide supporting evidence that a shift in climate towards cold and dry conditions during the Middle Pleistocene may have directly benefited Homo erectus populations in open habitats of North China. This general pattern of declining vegetation cover in the study area is consistent with climatic and environmental patterns in other regions of North China, which were probably influenced by global cooling during the Middle Pleistocene. © 2015 Elsevier B.V. Source


Liu C.,Capital Normal University | Liu C.,Resource Environment and Geographic Information System Beijing Key Laboratory | Liu C.,State Key Laboratory Cultivation Base Urban Environment Process and Digital Module | Wei M.-J.,Capital Normal University | And 5 more authors.
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology | Year: 2010

Exampled by measuring the selected frequency luminescence characters of surface sand of the Badain Jaran Desert, a standard method was set up. The process of measuring the selected frequency luminescence characters includes three steps. 1) Confirming the radiation dose and characteristic wavelength by measuring the dose response curve. 2) Confirming the distribution of the luminescence photon wavelengths by measuring the received spectra of separated frequency. 3) Verification the setting of the radiation dose by measuring the dose response curve again. Source


Zhao Q.-Y.,Capital Normal University | Zhao Q.-Y.,Resource Environment and Geographic Information System Beijing Key Laboratory | Zhao Q.-Y.,State Key Laboratory Cultivation Base Urban Environment Process and Digital Module | Wei M.-J.,Capital Normal University | And 5 more authors.
Yuanzineng Kexue Jishu/Atomic Energy Science and Technology | Year: 2014

Glow curves of abundant quartz powder were obtained with the RGD-3B thermoluminescence (TL) reader. TL peaks with 448, 551, 654, 756 K were identified at the heating rate of 5 K/s. The activation energy, frequency factor and lifetime of trapped charge were evaluated at ambient temperature for four peaks by the method of various heating rates. Within a certain range of activation energy, the equivalent dose increases exponentially with the activation energy. The equivalent dose increases from 54 Gy to 485 Gy with the temperature from 548 K to 608 K, and it fluctuates around 531 Gy with the temperature from 608 K to 748 K. Source


Zhou R.,Capital Normal University | Zhou R.,MOE Key Laboratory of Resource Environment and Geographic Information System in Beijing | Zhou R.,State Key Laboratory Cultivation Base Urban Environment Process and Digital Module | Wei M.-J.,Capital Normal University | And 8 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2013

The thermoluminescence characteristics and selected frequency luminescence characteristics of an orthoclase were studied using RGD-3B thermoluminescence dosimeter and BG2003 luminescence spectrograph. The result indicates that the orthoclase has three thermoluminescence peaks and the temperatures of these peaks are 148, 197 and 310°C respectively. The 197 and 310°C thermoluminescence peaks appear when it has been irradiated. The temperature of peak value deceases with the decease in warming rates. The luminescence signal is obvious at 290, 300, 310, 340, 400 and 480 nm wavelength with heat excitation. The luminescence signal is obvious at 280, 290, 300, 310, 320, 400, 460 and 480 nm wavelength with 532 nm light excitation. The certain linear relation exists between the photon counts from 400 nm and irradiation doses. It can also be used as a dosimeter. It has application potential in luminescence dating. Source


Liu J.-X.,Capital Normal University | Liu J.-X.,Resource Environment and Geographic Information System Beijing Key Laboratory | Liu J.-X.,State Key Laboratory Cultivation Base Urban Environment Process and Digital Module | Wei M.-J.,Capital Normal University | And 11 more authors.
Hedianzixue Yu Tance Jishu/Nuclear Electronics and Detection Technology | Year: 2013

The TL background radiation of the modern debris flow materials of KeTai and XiBaiLianYu Gully, which in White River Basin of Beijing, was studied using the thermo luminescence technology. The research indicates that the thermo luminescence signal of debris flow materials reduced obviously in the process of flow. The average equivalent doses of the provenance, circulation area and the accumulation area are respectively 63.19, 52.42 and 49.54 Gy. Because of the light fading, the surface sample's background radiation is less than that of the samples 5~10 cm from the surface. The residual background radiation of the surface debris flow material in White River Basin is between 11.2 to 28.5 ka and the result provides a foundation for using thermo luminescence technology to date old debris flow. Source

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