We have completed the pollen analyses of 252 sedimentary samples from Dahonggou section in Qaidam Basin covering the Cenozoic. Palynomorph extraction followed the routine process with HCl and HF treatments during the extraction. Airborne pollen-charcoal traps and surface-sediment samples from soils were collected to evaluate the relationship between pollen-charcoal contents and vegetation structure, and effect of sedimentary environment conditions on the pollen dispersal and deposition. Combined with pollen-charcoal data from other sections, we are going to establish the fire history spanning the last 30 Ma years, and to discuss the responds and feedbacks of the vegetation and fire to the climate changes. Our work is beneficial to the knowledge of the processes of aridification in Inner Asia and its mechanism. The submitted pollen data set is according to the proposal, and in order to guarantee data accuracy, 20% of the data have been examined in our lab by random sampling method. Data collection and analysis are continued, we hope our work can contribute more to the project in the next few years.
This data set contains a deep drilling paleomagnetic age data near the open sea in the middle reaches of Heihe River. The borehole is located at 99.432 E and 39.463 n with a depth of 550m. The samples of paleomagnetic age were taken at the interval of 10-50 cm. The paleomagnetic test was carried out in the Key Laboratory of Western Ministry of environmental education of Lanzhou University. The primary remanence of the samples was obtained by alternating demagnetization and thermal demagnetization, and the whole formation magnetic formation was obtained by using the primary remanence direction of each sample, and then the sedimentary age of the strata was obtained by comparing with the standard polarity column. The results show that the bottom boundary of the borehole is about 7 Ma and the top boundary is 0 ma.
Since the formation of Heihe River, sporopollen data samples have been collected from the drilling strata of Da'ao well in the middle reaches of Heihe River. Drilling location: 39.491 n, 99.605 E. The drilling depth is 140 meters. 128 samples of sporopollen are collected from top to bottom. At present, there are 19 data of sporopollen results, which are distributed in each sedimentary facies from top to bottom. The sporopollen samples were removed from carbonate, organic matter, silicate and other impurities in the laboratory, and the species and data of sporopollen were identified under the microscope. Sporopollen results mainly include the percentage content and number of trees, shrubs, herbs, aquatic, ferns and other families and genera.
Based on the study of the terrace formation age in the upper reaches of heihe river, photoluminescence samples were collected from the sediments of grade 6 river terrace near the upper reaches of qilian river.The quartz particles (38-63 microns) in the sample were isolated in the laboratory, the equivalent dose and dose rate in the quartz particles were measured, and the photoluminescence age of the sample was finally obtained.The obtained ages range from 5ka to 82ka, corresponding to the years of cutting down the terraces of all levels.
Since the formation of heihe, palynology data samples were collected from the borehole formation of dasunken well in the middle reaches of heihe.Borehole location: 39.491 n, 99.605 e.The borehole has a depth of 140 meters and 18 palynological samples are collected from top to bottom. Currently, there are 3 palynological results, which are distributed in each sedimentary phase from top to bottom.Impurities such as carbonate, organic matter and silicate were removed from palynology samples in the laboratory, and the palynology types and data were identified under the microscope.Palynology results mainly included the percentage and number of trees, shrubs, herbs, aquatic and ferns.
Data content: Standard ring-width chronology derived from Wilson juniper shrub around the northern shore of the Nam Co Lake; May-June SZI (Standardized Moisture Anomaly Index) drought reconstruction for the Nam Co region. Time span: 1605 to 2010. Temporal resolution: Yearly. Application and prospects: Hydroclimate study on the south-central Tibetan Plateau.
This data is the grain size data set of the XS loess section at Ganzi in the east of Qinghai Tibet Plateau. The whole section is 10 meters thick, and the grain size analysis is carried out according to the interval of 2.5cm. A total of 398 groups of grain size data are obtained. The grain size analysis was carried out at the Key Laboratory of Western China's Environmental Systems（Ministry of Education), Lanzhou University. Before the measurement, the organic matter and carbonate in the sample were removed by H2O2 and hydrochloric acid, then adding the sodium hexago-hydrophosphate and vibrating for about 10 min to disperse samples by using ultrasonic apparatus. All measurements are conducted by using the Mastersizer 2000. This data reflects variations of the loess grain size since the last interglacial, which is of great importance for understanding past evionroment changes in the eastern Tibet Plateau.
This data is a standard chronology of the ring width of five species of tamarix chinensis shrub in the lakeside terrace of the east juyan sea, which represents the changes of the lake water level in the east juyan sea in the past 100 years.
This magnetic susceptibility data set of the XS loess section at Ganzi in the eastern Tibet Plateau. We analyzed the magnetic susceptibility of the top part of the loess sequence at 5cm intervals, and obtained 200 sets of magnetic susceptibility data. The experimental analysis was completed in the Key Laboratory of Western China's Environmental Systems（Ministry of Education), Lanzhou University. Air-dried and grind the samples were put it into a non-magnetic cubic box, and measured by the British Bartington MS2. The result indicates the varations of the low frequency magnetic susceptibility of the Loess sequence since the Last Interglacial at Ganzi area, which is of great importance for understanding past environment changes in the eastern Tibet Plateau.