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Junsheng Nie - One of the best experts on this subject based on the ideXlab platform.
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provenance of the upper miocene pliocene red Clay Deposits of the chinese loess plateau
Earth and Planetary Science Letters, 2014Co-Authors: Junsheng Nie, Wenbin Peng, Andreas Moller, Yougui Song, Daniel F Stockli, Thomas Stevens, Brian K Horton, Shanpin LiuAbstract:A clear understanding of the provenance of late Cenozoic Chinese loess and the underlying Red Clay Deposits will shed light on the history and mechanisms of Asian aridification. Although much progress has been made in understanding the source of Quaternary loess on the Chinese Loess Plateau (CLP), the provenance of the underlying upper Miocene–Pliocene Red Clay sequence is largely unknown. Here we present the first provenance history of the Red Clay sequence based on zircon U–Pb ages from the central CLP. Visual and statistical analyses of the U–Pb age populations and comparison with results from potential source regions reveals that (1) the lowermost Red Clay of the late Miocene (depositional age of ∼ 8M a) is likely sourced from the nearby Liupan Mountains and the Qaidam Basin; (2) the middle Red Clay (5.5–4 Ma) of the early-mid Pliocene is sourced mainly from the Taklamakan desert, transported via lower-level westerly winds; (3) the upper Red Clay of the late Pliocene (∼ 3M a) is sourced from mixed areas, although western source materials from middle-northern Tibetan plateau (including Qaidam Desert sediments and materials eroded from the Qilian Mountains) sediments appear to dominate; and (4) the Quaternary loess is also sourced from mixed source regions, albeit with dominant northern CLP proximal desert sediments transported via winter monsoon winds, which in turn may be transported from mountain source regions of the northeastern Tibet and Gobi Altai via major river systems. This long term shift in sources suggests a progressive eastward aridification during the Pliocene in Asia with the specific timing of provenance shifts synchronous with large-scale climatic transitions and Tibetan uplift,
Yuan Shang - One of the best experts on this subject based on the ideXlab platform.
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aeolian silt transport processes as fingerprinted by dynamic image analysis of the grain size and shape characteristics of chinese loess and red Clay Deposits
Sedimentary Geology, 2017Co-Authors: Yuan Shang, Anu Kaakinen, C J Beets, Maarten A PrinsAbstract:Abstract This study applied dynamic image analysis (DIA; Sympatec Qicpic) to characterize the grain size and shape of Chinese aeolian sediments in order to fingerprint their transportation processes. This is the first time this technique has been applied to late Neogene and Quaternary silt particles (2–63 μm) from the Chinese Loess Plateau (CLP). We selected four well-studied Quaternary loess-palaeosol sequences along a north-south transect across the CLP and compared their grain size distribution obtained by DIA with that yielded by laser diffraction particle size analysis (LD; Fritsch Analysette 22 and Sympatec HELOS KR). This comparison demonstrated that DIA is successfully able to differentiate loess units from palaeosols, and to characterize clearly spatiotemporal variations in the grain size records of loess-palaeosol sequences formed during the last two glacial and interglacial periods. This is consistent with grain size results obtained using LD. DIA is also able to characterize spatial variations in the more fine-grained aeolian Red Clay Deposits underlying the Quaternary loess, and allows the quantification of the fluvial contribution to Red Clay sequences. DIA of the characteristics of grain shapes in loess-palaeosol sequences and Red Clay Deposits revealed a systematic pattern, whereby the aspect ratio decreased with increasing grain size, indicating that systematic shape sorting occurred during the aeolian transportation of these dust particles. It could be inferred from our study that particles in a certain grain size range correspond to a specific aspect ratio range, and may in turn be aerodynamically distinguishable from each other and further correlated with the wind velocity/strength. Also evident from analysis of our DIA data was a subtle but systematic downwind decrease in the aspect ratio of the particles in the loess units. This observation suggests that elongated and/or flat particles (with a low aspect ratio) were transported further downwind than more symmetrically shaped particles (with a high aspect ratio). This study indicates that DIA of grain size and shape characteristics can be an additional powerful tool for identifying grain size and shape sorting trends, determining the dominant mode of transport, and reconstructing transport pathways of silt-sized aeolian sediments.
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variations in the provenance of the late neogene red Clay Deposits in northern china
Earth and Planetary Science Letters, 2016Co-Authors: Yuan Shang, C J Beets, Maarten A Prins, Hui Tang, Yann Lahaye, Roel Van Elsas, Leena Sukselainen, Anu KaakinenAbstract:Abstract The voluminous loess-Red Clay Deposits in northern China forming part of the Chinese Loess Plateau (CLP) are valuable terrestrial archives of climatic evolution for the late Cenozoic Era. Fundamental in reconstructing the late Miocene and Pliocene wind patterns and aridification history is a detailed knowledge of the provenance of these Deposits. This paper provides end member modelling of bulk grain-size distributions and U–Pb dating of detrital zircons for three distant Red Clay sequences in the northeastern (Baode), southern (Lantian) and western (Dongwan) CLP. Data show that these different sections each display a distinctive compositional structure indicating variable depositional processes, but they also share two significant zircon age populations of 200–300 Ma and 400–500 Ma. While the Permian–Triassic (200–300 Ma) group accounts for a larger proportion of zircons' ages in the northeastern (NE) CLP, the Ordovician–Silurian (400–500 Ma) component is dominant in the southern and western CLP. It is suggested that the Red Clay in the southern and western CLP was mainly derived from the Northern Tibetan Plateau (NTP) and the Taklimakan desert by low-level westerly winds. Samples of the NE CLP show an increased signature of sediments transported by near-surface northwesterly winds from the broad area of the Central Asian Orogen Belt (CAOB). This spatial transport and deposition pattern is supported by the results from the backtrace trajectory modelling of the dominant dust transport pathways in the CLP. It is noted that the Red Clay sample of around 3.6 Ma obtained from the NE CLP shows increased detrital contributions from its west, possibly indicating an intensified westerly wind strength and/or aridity of the NTP and Taklimakan desert due to the uplift of the Tibetan Plateau and Tianshan Mountains in the Pliocene. The onset of enhanced drainage of the Yellow River caused by the increased denudation of the NETP since 3.6 Ma could also have contributed to this.
Nathalie Fagel - One of the best experts on this subject based on the ideXlab platform.
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moroccan Clay Deposits physico chemical properties in view of provenance studies on ancient ceramics
Applied Clay Science, 2019Co-Authors: Meriam El Ouahabi, Hicham El Boudour El Idrissi, Lahcen Daoudi, Mouhssin El Halim, Nathalie FagelAbstract:Abstract Features of Clayey raw materials from most important traditional pottery centers in the vicinity of the main medieval sites in Morocco, and their fired products were investigated. Besides Clay from the North of Morocco, the used raw material was illitic Clays (10–100%) and smectite-rich Clays (0–67%) with variable amount of kaolinite, quartz and feldspars. Chlorite was also present in a small amount. The main major oxides were Si2O, Al2O3 and CaO. The fired tests (800–1100 °C) displayed a decrease in open porosity of the sintered Clay by raising the temperature, mainly from 1000 °C due to the inception of melting. This change was coupled with the change in mineralogical composition. New crystalline phases as Ca-silicates (diopside and gehlenite), hematite, spinel and mullite occurred during firing process, attesting to the inception of melting and were responsible for porosity reduction. Reference Clays for pottery were established based on the Clay mineralogy and chemical composition. The present study would help to answer some archeological questions concerning possible sourcing areas for archeological ceramics, to determine techniques for the production of artefacts, and then to interpret cultural influences. Furthermore, the obtained results will support the inception of development of a compositional database for Moroccan pottery.
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mineralogy and geochemical features of foumban Clay Deposits west cameroon genesis and potential applications
Clay Minerals, 2018Co-Authors: Nkalih A Mefire, Yongue R Fouateu, Andre Njoya, Jacques Richard Mache, P Pilate, Frederic Hatert, Nathalie FagelAbstract:Five Clay Deposits in Foumban, west Cameroon, were studied for their morphological, mineralogical and geochemical properties to determine their suitability for ceramics. The Clays were examined with X-ray diffraction, X-ray fluorescence, thermal gravimetric analysis and Fourier-transform infrared spectroscopy. Field studies showed that a homogeneous Clayey layer occurs at the upper part of the laterite cover of the interfluves, while the valleys are occupied by a Clayey heterogeneous hydromorphic material. The Clays are composed of kaolinite, illite, smectite and chlorite, associated with quartz, K-feldspars, plagioclase, goethite, traces of rutile and hematite. Geochemical analyses of these samples show a relatively large amount of SiO2 (45–71%), Al2O3 (14–31%) and relatively little Fe2O3 (up to 11%), suggesting weathering of mainly granitic and rhyolitic parent rocks. The majority of these Clays may be used in the production of structural ceramics such as bricks (refractory or not) and tiles. The relatively high proportion of the alkalis (K2O + Na2O; 6–8%) in some samples from Marom and Njindare areas might be responsible for the low firing temperatures. The abundance of smectite limits the application of some Koutaba and Marom Clays for structural ceramics, while the high Fe2O3 contents (>8%) in some Bangourain Clays indicate that some pre-treatment might be necessary prior to use.
Xiaoke Qiang - One of the best experts on this subject based on the ideXlab platform.
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iron oxide characteristics of mid miocene red Clay Deposits on the western chinese loess plateau and their paleoclimatic implications
Palaeogeography Palaeoclimatology Palaeoecology, 2017Co-Authors: Hui Zhao, Xiaoke QiangAbstract:Abstract The middle Miocene climate optimum (MMCO, 14.3–16.3 Ma) was a warm climatic interval that may provide an analog for future climates in the context of ongoing global warming. In continental regions, however, reconstruction of the MMCO remains controversial due to the lack of robust proxies from continuous sedimentary sequences. In this study, we investigated the composition and relative abundance of pedogenic iron oxides in the Zhuanglang Red Clay Deposits from the western Chinese Loess Plateau, using rock magnetic, color reflectance, and geochemical analyses. Our aim was to assess the climatic sensitivity of iron oxides in order to produce robust proxies for reconstructing regional temperature and moisture relationships during the MMCO. Our results indicate that the MMCO in the study region was characterized by high effective precipitation, relatively high temperature and strong pedogenesis, suggesting a strong East Asian summer monsoon (EASM). The strengthening of the EASM intensity during the MMCO is consistent with records of enhanced terrigenous chemical weathering in the South China Sea, and the occurrence of a relatively warm and humid climate on a global scale, implying the strong coupling between Asian monsoon evolution and global climate change during the middle Miocene. In addition, the magnetic susceptibility record of the Zhuanglang Red Clay demonstrates that eccentricity played the dominant role in controlling the EASM during the MMCO.
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changes in grain size and sedimentation rate of the neogene red Clay Deposits along the chinese loess plateau and implications for the palaeowind system
Science China-earth Sciences, 2005Co-Authors: Lingjuan Wen, Xiaoke QiangAbstract:The wind system responsible for transporting dust onto the Chinese Loess Plateau during the late Miocene and Pliocene is still unknown and recent investigations highlight many controversies. This report aims to investigate spatiotemporal changes in grain-size and sedimentation rate of the Neogene Red Clay Deposits in north China and to explore palaeoclimatic changes during the late Miocene and Pliocene, in particular the palaeowind system that transported dust. Samples were collected from eight Red Clay sections on the Loess Plateau. Measurement and analysis show that there is a clear southward decrease in the mean grain-size index and in the coarse particle fraction (>20 i m). At Jiaxian site on the northern Loess Plateau, the average mean grain-size is around 20 i m, while at Lantian site in the south, the mean is around 9 i m. The coarse particle fraction >20 i m makes up 24.4% and 5.6%, at the two sites respectively. This distinct diversity of grain-size in the aeolian Red Clay deposit between the north and south indicate that the palaeodust was transported mainly by northerly low-level winds. The grain-size variations in the Red Clay Deposits can also be divided into three stages (the lower, the middle and the upper interval): grain-size of the lower stage is significantly coarser than that of the middle stage, but finer than that of the upper stage. As a consequence, the intensity of pa-laeowind and desiccation of the dust source region during the late Miocene and Pliocene can be divided into three stages: 6.2-5.4 Ma, 5.4-3.5 Ma and 3.5-2.6 Ma. Strength of the palaeowind during the middle stage (5.4-3.5 Ma) is weaker than that of the previous and subsequent stages and the intensity of palaeowind during the latest stage (3.5-2.6 Ma) is stronger than that of the early time (6.2-5.4 Ma). Variations in the sedimentation rate of the Red Clay deposit can also be divided into three stages: the earlier, the middle and the later interval. The sedimentation rate of the earlier stage is higher than during the middle stage, but lower than during the later one. This is a clear indicator of changes in the palaeowind intensity and aridity in the dust source region and may be linked with global ice volume changes during the late Miocene and the Pliocene.
Shanpin Liu - One of the best experts on this subject based on the ideXlab platform.
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provenance of the upper miocene pliocene red Clay Deposits of the chinese loess plateau
Earth and Planetary Science Letters, 2014Co-Authors: Junsheng Nie, Wenbin Peng, Andreas Moller, Yougui Song, Daniel F Stockli, Thomas Stevens, Brian K Horton, Shanpin LiuAbstract:A clear understanding of the provenance of late Cenozoic Chinese loess and the underlying Red Clay Deposits will shed light on the history and mechanisms of Asian aridification. Although much progress has been made in understanding the source of Quaternary loess on the Chinese Loess Plateau (CLP), the provenance of the underlying upper Miocene–Pliocene Red Clay sequence is largely unknown. Here we present the first provenance history of the Red Clay sequence based on zircon U–Pb ages from the central CLP. Visual and statistical analyses of the U–Pb age populations and comparison with results from potential source regions reveals that (1) the lowermost Red Clay of the late Miocene (depositional age of ∼ 8M a) is likely sourced from the nearby Liupan Mountains and the Qaidam Basin; (2) the middle Red Clay (5.5–4 Ma) of the early-mid Pliocene is sourced mainly from the Taklamakan desert, transported via lower-level westerly winds; (3) the upper Red Clay of the late Pliocene (∼ 3M a) is sourced from mixed areas, although western source materials from middle-northern Tibetan plateau (including Qaidam Desert sediments and materials eroded from the Qilian Mountains) sediments appear to dominate; and (4) the Quaternary loess is also sourced from mixed source regions, albeit with dominant northern CLP proximal desert sediments transported via winter monsoon winds, which in turn may be transported from mountain source regions of the northeastern Tibet and Gobi Altai via major river systems. This long term shift in sources suggests a progressive eastward aridification during the Pliocene in Asia with the specific timing of provenance shifts synchronous with large-scale climatic transitions and Tibetan uplift,