The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Fahu Chen - One of the best experts on this subject based on the ideXlab platform.
-
quartz osl dating of Loess deposits since the late glacial in the southeast of caspian sea
Quaternary International, 2020Co-Authors: Leibin Wang, Hassan Azarmdel, Farhad Khormali, Manfred Frechen, Fahu Chen, Guoqiang LiAbstract:Abstract Here we present Loess deposit since the late glacial dated by OSL technique in the southeast of the Caspian Sea, bordering continents of Asia and Europe. Chronology of Loess deposits are rarely reported in Eastern Europe and Western Asia, especially for their spacious mid-latitude adjacent region, between Balkans to the west and Pamirs to the east. In this study, an OSL-based chronology was developed for Loess deposits in northern Iranian Plateau, based on the YBD Loess profile which locates close to center of hilly Iranian Loess Plateau in the southeast of the Caspian Sea and on the northern slope of the Alborz Mountains. The OSL characteristics and their reliability were investigated on coarse-grained quartz (63–90 μm) of the profile, a preheat plateau test and dose recovery test of which reveal that the lower preheat is suitable for Loess equivalent dose determination in the area. In addition, the SAR-OSL is an appropriate methodology for dating Loess deposited since the late glacial in situ. With preservation of a complete record of Loess accumulation since the late glacial, YBD section contains a potentially valuable paleoclimatic record for Caspian region and hence the vast transitional region between Asia and Europe.
-
quartz osl dating of Loess deposits since the late glacial in the southeast of caspian sea
Quaternary International, 2020Co-Authors: Haitao Wei, Leibin Wang, Hassan Azarmdel, Farhad Khormali, Manfred Frechen, Fahu ChenAbstract:Abstract Here we present Loess deposits since the late glacial dated by OSL technique in the southeast of the Caspian Sea, bordering continents of Asia and Europe. Chronology of Holocene Loess deposits are rarely reported in Eastern Europe and Western Asia, especially for their spacious mid-latitude adjacent region, between Balkans to the west and Pamirs to the east. In this study, an OSL-based chronology was developed for Loess deposits in northern Iranian Plateau, based on the YBD Loess profile which locates close to center of hilly Iranian Loess Plateau in the southeast of the Caspian Sea and on the northern slope of the Alborz Mountains. The OSL characteristics and their reliability were investigated on coarse-grained quartz (63–90 μm) of the profile, a preheat plateau test and dose recovery test of which reveal that the lower preheat is suitable for Loess equivalent dose determination in the area. In addition, the SAR-OSL is an appropriate methodology for dating Loess deposited since the late glacial in situ. With preservation of a complete record of Loess accumulation since the late glacial, YBD section contains a potentially valuable paleoclimatic record for Caspian region and hence the vast transitional region between Asia and Europe.
-
paleoenvironmental changes recorded in a luminescence dated Loess paleosol sequence from the tianshan mountains arid central asia since the penultimate glaciation
Earth and Planetary Science Letters, 2016Co-Authors: Zhiguo Rao, Leibin Wang, Yanwu Duan, Dunsheng Xia, David B Madsen, Jia Jia, Haitao Wei, Mingrui Qiang, Jianhui Chen, Fahu ChenAbstract:Abstract Mid-latitude arid central Asia (ACA) is one of the driest regions in the world and is a key source area of global atmospheric dust. Loess records of paleoclimatic changes in ACA are complex and interpretations are problematic due primarily to the lack of robust chronologies. Quartz OSL and K-feldspar pIRIR dating methods were employed to date 8 quartz and 30 K-feldspar samples from a 30 m Loess sequence (BYH10 section) on the northern slope of the Tianshan Mountains, central ACA, northwest China. The reliability of quartz and K-feldspar ages was monitored by internal checks of luminescence characteristics and by comparison of the quartz and K-feldspar ages. The section lithology, proxy indexes of grain size and magnetic susceptibility, and the high resolution OSL chronology together indicate: (1) Quartz OSL dating can be used to date ACA Loess samples less than 40 ka, while K-feldspar pIRIR dating is reliable for Loess samples at least as old as ∼150 ka from ACA; (2) Aeolian Loess began to be deposited on the northern slope of Tianshan Mountains beginning at least ∼145 ka ago, and was deposited primarily during the penultimate and last glaciation periods; (3) Rapid Loess deposition occurred during MIS 6, MIS 4 to early-mid MIS 3, and MIS 2, but little or no Loess deposition occurred during MIS 5, MIS 3a and MIS 1; (4) This Loess depositional sequence is comparable to previously published stalagmite growth records in the region on glacial-interglacial cycles. Rapid dust deposition and lack of stalagmite growth during glacials, and lack of Loess deposition and stalagmite growth during interglacials, indicate a climatic pattern of wet-warm (interglacial) and dry-cold (glacial) climatic regimes on orbital cycles in ACA; (5) Variation in the Loess deposition rates in ACA was much larger than in the central Loess plateau during the last glaciation; (6) Depositional hiatuses of >50 kyr occur in ACA Loess sequences, and high resolution chronologies are needed when reconstructing past climatic changes.
Yougui Song - One of the best experts on this subject based on the ideXlab platform.
-
origin of Loess deposits in the north tian shan piedmont central asia
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Yougui Song, Kathryn E Fitzsimmons, Xiuling Chen, Charlotte Prudhomme, Xiulan ZongAbstract:Abstract Loess deposits are widely distributed along the mountain piedmonts of Central Asia. The transport processes and origins of Central Asian Loess sediments remain poorly understood. Here we investigate the origin and formation of Loess along the northern piedmont of the Tian Shan based on trace element (including rare earth element) ratios and multidimensional scaling analysis. Our results indicate that the Loess has undergone weak chemical weathering. Using a selection of geochemical fingerprinting techniques based on Pearson correlation and Kruskal–Wallis H tests, we establish a genetic link between alluvial-proluvial fans/plains, deserts, and Loess along the Tian Shan piedmont in northern Kyrgyzstan and southern Kazakhstan. The unsorted sediments on the piedmont slopes and alluvial-proluvial plains are common sources for both deserts and Loess to the north of the Tian Shan. Dune sediments are not the main source of the fine-grained Loess. Origin and formation of Central Asian Loess is strongly dependent on local topographic context and wind dynamics. Only once Loess provenance and formation has been understood across both space and time can reliable interpretations of palaeoclimatic proxies in these deposits be made.
-
a combined luminescence and radiocarbon dating study of the ili Loess central asia
Quaternary Geochronology, 2012Co-Authors: Yougui Song, Jingdong Zhao, Peng Cheng, Mengxiu ZengAbstract:Abstract Similar to the Loess in the Chinese Loess Plateau (CLP), the Loess deposits in the Ili basin of Central Asia arid area play an important role in understanding the climate and environmental changes. However, in contrast to the intensively investigated Loess deposits in the CLP, the Ili Loess is still insufficiently known and poorly understood. The geochronology study of the Ili Loess remains controversial. In order to examine the potential of optically stimulated luminescence (OSL) dating for the Ili Loess, we carry out a combined luminescence and radiocarbon dating study on a 6.9 m Loess section in the south margin of the Ili basin. Polymineral fine grains were investigated by post infrared (IR) OSL using a Multiple-Aliquot Regenerative-dose (MAR) protocol. Radiocarbon dating of organic carbon were carried in a 3 Megavolt (MV) multi-element Accelerator Mass Spectrometry (AMS). The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field, which is well correlated with that of the CLP, but the AMS 14 C ages are much younger than the OSL and assumed stratigraphical ages. Thus, the OSL dating technique may provide an absolute chronology in this Loess section. Further methodological approaches and more samples analysis will lead to the improvement of this chronology for high-resolution paleoclimatic interpretation.
-
consistent grain size distribution of pedogenic maghemite of surface soils and miocene Loessic soils on the chinese Loess plateau
Journal of Quaternary Science, 2010Co-Authors: Yougui Song, Junsheng Nie, John W King, Ramon EgliAbstract:ABSTRACT: There is agreement that ultrafine maghemite grains (<100nm) are responsible for themagnetic enhancement of Chinese Loess. Recent studies show that grain size distribution of ultrafinepedogenic maghemite grains within the aeolian sequences on the central Chinese Loess Plateaudeposited in the last 8 Ma is consistent. However, whether the observed grain size distribution ofultrafine pedogenic maghemite grains can be observed in the western Chinese Loess Plateau andmodernsoilsisnotentirelyclear.HerewefindthatyoungsurfacesoilsamplesacrosstheChineseLoessPlateau and early Neogene Loessic soils from the western Chinese Loess Plateau also show consistentgrain size distribution with that of ultrafine pedogenic maghemite grains on the central Chinese LoessPlateau. The fact that young surface soil samples show apparent magnetic enhancement suggests thatthe ultrafine pedogenic maghemite grains derive from oxidation of ultrafine magnetite grains. Copy-right # 2009 John Wiley & Sons, Ltd. KEYWORDS: Loess Plateau; magnetic susceptibility; ARM; Miocene Loess; maghemite.
Manfred Frechen - One of the best experts on this subject based on the ideXlab platform.
-
quartz osl dating of Loess deposits since the late glacial in the southeast of caspian sea
Quaternary International, 2020Co-Authors: Leibin Wang, Hassan Azarmdel, Farhad Khormali, Manfred Frechen, Fahu Chen, Guoqiang LiAbstract:Abstract Here we present Loess deposit since the late glacial dated by OSL technique in the southeast of the Caspian Sea, bordering continents of Asia and Europe. Chronology of Loess deposits are rarely reported in Eastern Europe and Western Asia, especially for their spacious mid-latitude adjacent region, between Balkans to the west and Pamirs to the east. In this study, an OSL-based chronology was developed for Loess deposits in northern Iranian Plateau, based on the YBD Loess profile which locates close to center of hilly Iranian Loess Plateau in the southeast of the Caspian Sea and on the northern slope of the Alborz Mountains. The OSL characteristics and their reliability were investigated on coarse-grained quartz (63–90 μm) of the profile, a preheat plateau test and dose recovery test of which reveal that the lower preheat is suitable for Loess equivalent dose determination in the area. In addition, the SAR-OSL is an appropriate methodology for dating Loess deposited since the late glacial in situ. With preservation of a complete record of Loess accumulation since the late glacial, YBD section contains a potentially valuable paleoclimatic record for Caspian region and hence the vast transitional region between Asia and Europe.
-
quartz osl dating of Loess deposits since the late glacial in the southeast of caspian sea
Quaternary International, 2020Co-Authors: Haitao Wei, Leibin Wang, Hassan Azarmdel, Farhad Khormali, Manfred Frechen, Fahu ChenAbstract:Abstract Here we present Loess deposits since the late glacial dated by OSL technique in the southeast of the Caspian Sea, bordering continents of Asia and Europe. Chronology of Holocene Loess deposits are rarely reported in Eastern Europe and Western Asia, especially for their spacious mid-latitude adjacent region, between Balkans to the west and Pamirs to the east. In this study, an OSL-based chronology was developed for Loess deposits in northern Iranian Plateau, based on the YBD Loess profile which locates close to center of hilly Iranian Loess Plateau in the southeast of the Caspian Sea and on the northern slope of the Alborz Mountains. The OSL characteristics and their reliability were investigated on coarse-grained quartz (63–90 μm) of the profile, a preheat plateau test and dose recovery test of which reveal that the lower preheat is suitable for Loess equivalent dose determination in the area. In addition, the SAR-OSL is an appropriate methodology for dating Loess deposited since the late glacial in situ. With preservation of a complete record of Loess accumulation since the late glacial, YBD section contains a potentially valuable paleoclimatic record for Caspian region and hence the vast transitional region between Asia and Europe.
-
middle and late pleistocene Loess sequences at batajnica vojvodina serbia
Quaternary International, 2009Co-Authors: Slobodan B Markovic, Urlich Hambach, Ludwig Zoller, Norm Catto, Mladjen Jovanovic, Bjorn Buggle, Bjorn Machalett, Bruno Glaser, Manfred FrechenAbstract:Abstract Loess sequences in the Vojvodina region (Northern Serbia) reveal a continuous record of paleoclimatic variations during the Middle and Late Pleistocene. The most detailed stratigraphic information comes from remarkable exposures on the cliffs of the right Danube bank from Vukovar to Belgrade. The Batajnica Loess section has been recognized as one of the most complete Middle and Late Pleistocene records in this region. A more than 40 m thick Loess–paleosol succession represents environmental transition from relative thin Loess layers and rubified soils in lower part of profile to thick Loess and fossil chernozems characterizing the last three glacial–interglacial cycles. The proposed stratigraphic model is based on a detailed magnetic susceptibility (MS) record which is related to the deep-sea isotope stratigraphy and on correlation with other Eurasian Loess records using the distinct MS pattern of selected Loess–paleosol couplets. This new stratigraphic model suggests serious revision of previous chronological interpretations. MS as function of depth shows a well-known pattern of low values in Loess and high values in paleosols indicating strong enhancement of magnetic minerals during soil formation. With the exception of the recent soil (V-S0) which is strongly contaminated by archaeological artifacts, the third paleosol V-S3 reveals the highest values in MS and a very distinct double peak. The rock magnetic signal at Batajnica resembles the typical pattern of the enviromagnetic records determined from other Eurasian Loess sites. The paleopedological interpretations, rubification index values and rock magnetic record at Batajnica yield valuable data for the reconstruction of paleoclimatic fluctuations for the last 5 glacial–interglacial cycles at least. Moreover, the record provides an important link between the classical Central European Loess sites and the Central Asian and Chinese Loess provinces.
-
luminescence and amino acid racemization chronology of the Loess paleosol sequence at suttő hungary
Quaternary International, 2009Co-Authors: Agnes Novothny, Manfred Frechen, Erzsebet Horvath, Balazs Bradak, Eric A Oches, William D Mccoy, Thomas StevensAbstract:Abstract The Loess–paleosol sequences in Hungary provide an excellent Upper Pleistocene climate archive of the Carpathian Basin. Loess deposits up to 20 m thick cover the Suttő travertine complex, located in the very northern part of Hungary, next to the right bank of the Danube River. The Loess is intercalated with two weakly developed greyish horizons, two thinner-brownish steppe-like soils and a pedocomplex, including a reddish-brown clay-enriched horizon covered by a chernozem-like paleosol. Infrared optically stimulated luminescence (IRSL) dating was applied on polymineral fine grain material to determine the depositional age of the Loess. The uppermost Loess yields IRSL age estimates ranging from 15 to 40 ka. The Loess on top of the pedocomplex yields IRSL age estimates ranging from 48 to 60 ka. The pedocomplex most likely correlates with the Marine Oxygen Isotope Stage (MIS) 5 interglacial period. The Loess from below the pedocomplex was deposited during the penultimate glaciation, as evidenced by amino acid racemization (AAR) results. Further independent age control is provided by radiocarbon dating for the upper part of the profile and by uranium-series (230Th/234U) ages correlating the travertine below the Loess with MIS 7–8. The magnetic susceptibility record through the sequence shows a strong correlation with the Loess layers and soil horizons.
Kathryn E Fitzsimmons - One of the best experts on this subject based on the ideXlab platform.
-
origin of Loess deposits in the north tian shan piedmont central asia
Palaeogeography Palaeoclimatology Palaeoecology, 2020Co-Authors: Yougui Song, Kathryn E Fitzsimmons, Xiuling Chen, Charlotte Prudhomme, Xiulan ZongAbstract:Abstract Loess deposits are widely distributed along the mountain piedmonts of Central Asia. The transport processes and origins of Central Asian Loess sediments remain poorly understood. Here we investigate the origin and formation of Loess along the northern piedmont of the Tian Shan based on trace element (including rare earth element) ratios and multidimensional scaling analysis. Our results indicate that the Loess has undergone weak chemical weathering. Using a selection of geochemical fingerprinting techniques based on Pearson correlation and Kruskal–Wallis H tests, we establish a genetic link between alluvial-proluvial fans/plains, deserts, and Loess along the Tian Shan piedmont in northern Kyrgyzstan and southern Kazakhstan. The unsorted sediments on the piedmont slopes and alluvial-proluvial plains are common sources for both deserts and Loess to the north of the Tian Shan. Dune sediments are not the main source of the fine-grained Loess. Origin and formation of Central Asian Loess is strongly dependent on local topographic context and wind dynamics. Only once Loess provenance and formation has been understood across both space and time can reliable interpretations of palaeoclimatic proxies in these deposits be made.
-
Loess accumulation in the tian shan piedmont implications for palaeoenvironmental change in arid central asia
Quaternary International, 2016Co-Authors: Kathryn E Fitzsimmons, Tobias Sprafke, Christoph Zielhofer, Christina Gunter, Jeanmarc Deom, Renato Sala, Radu IovitaAbstract:Whilst correlations have been made between the Loess of Europe and China, deposits in Central Asia have remained largely overlooked by scientific investigation. The nature of the relationship between Loess accumulation and palaeoclimate at the core of the Eurasian Loess belt is particularly poorly understood. Here we reconstruct palaeoenvironmental change in Central Asia over the last 40 ky based on data from the Remizovka Loess profile, in the northern foothills of the Tian Shan in southern Kazakhstan. Our interpretations are based on synthesis of chronostratigraphic, colour and magnetic susceptibility data, supported by chronostratigraphies from two additional sites nearby, Maibulak and Valikhanova. All three sites record substantially increased Loess accumulation during late MIS 3 into the global last glacial maximum (gLGM). At Remizovka, increased Loess flux occurred in two pulses at c. 38-25 ka and 22-18 ka, with the intervening period involving incipient pedogenesis. At Maibulak, two Loess pulses at c. 40-30 ka and c. 28-22 ka are separated by a weakly developed paleosol which may date to the same time as pedogenesis at Remizovka. There is additional possible periglacial influence at Maibulak from c. 40–33.5 ka. At Valikhanova, there is some age overlap between paleosol and Loess samples, but overall Loess accumulation appears to have increased at c. 42-35 ka, c. 30 ka and the gLGM, with pedogenesis occurring >40 ka and c. 32 ka. At all three sites, Holocene Loess accumulation is minimal; this period is characterised by pedogenesis. The chronostratigraphic variability between our sites highlights a need to interrogate climate-driven models for Loess formation in piedmont environments. We interpret our data in the context of regional palaeoenvironmental archives to indicate that Loess accumulation increased coeval with MIS 3 glacial advance in the Tian Shan, which was facilitated by northward expansion of the Asian monsoon and associated increase in precipitation. We hypothesise that increased ice volume impeded teleconnections with the temperate zone westerlies to the north; these were compressed against the piedmont resulting in increased wind strength and facilitating increased Loess flux. Peak Loess accumulation during the gLGM occurred under colder, drier climatic conditions, with reduced but sustained glacial ice volume and persistent influence of the westerlies in the arid Central Asian piedmont Loess belt. In the absence of more widespread, reliably dated palaeoenvironmental records from the region, our data become of critical importance for understanding past environmental conditions in Central Asia, relative to elsewhere in Eurasia and globally.
-
danube Loess stratigraphy towards a pan european Loess stratigraphic model
Earth-Science Reviews, 2015Co-Authors: Slobodan B Markovic, Urlich Hambach, Kathryn E Fitzsimmons, Bjorn Buggle, George Kukla, Thomas Stevens, Phil Gibbard, Michael Zech, Zhengtang GuoAbstract:The Danube River drainage basin is the second largest river catchment in Europe and contains a significant and extensive region of thick Loess deposits that preserve a record of a wide variety of recent and past environments. Indeed, the Danube River and tributaries may themselves be responsible for the transportation of large volumes of silt that ultimately drive Loess formation in the middle and lower reaches of this large catchment. However, this vast Loess province lacks a unified stratigraphic scheme. European Loess research started in the late 17th century in the Danube Basin with the work of Count Luigi Ferdinand Marsigli. Since that time numerous investigations provided the basis for the pioneering stratigraphic framework proposed initially by Kukla (1970, 1977) in his correlations of Loess with deep-sea sediments. Loess-palaeosol sequences in the middle and lower reaches of the Danube River basin were a key part of this framework and contain some of the longest and most complete continental climate records in Europe, covering more than the last million years. However, the very size of the Danube Loess belt and the large number of countries it covers presents a major limiting factor in developing a unified approach that enables continental scale analysis of the deposits. Local Loess-palaeosol stratigraphic schemes have been defined separately in different countries and the difficulties in correlating such schemes, which often change significantly with advances in age-dating, have limited the number of basin-wide studies. A unified basin-wide stratigraphic model would greatly alleviate these difficulties and facilitate research into the wider significance of these Loess records. Therefore we review the existing stratigraphic schemes and define a new Danube Basin wide Loess stratigraphy based around a synthetic type section of the Mosorin and Stari Slankamen sites in Serbia. We present a detailed comparison with the sedimentological and palaeoclimatic records preserved in sediments of the Chinese Loess Plateau, with the oxygen isotope records from deep-sea sediments, and with classic European Pleistocene stratigraphic subdivisions. The hierarchy of Danubian stratigraphic units is determined by climatically controlled environmental shifts, in a similar way to the Chinese Loess stratigraphic scheme. A new unified Danube Loess stratigraphic model has a number of advantages, including preventing confusion resulting from the use of multiple national schemes, a more transparent basis, and the potential to set Pleistocene palaeoenvironmental changes recorded in the Danube catchment area into a global context. The use of a very simple labelling system based on the well-established Chinese Loess scheme facilitates interpretation of palaeoenvironmental information reported from the Danube Basin Loess sites in a wider more accessible context that can be readily correlated world-wide. This stratigraphic approach also provides, for the first time, an appropriate framework for the development of an integrated, pan-European and potentially pan-Eurasian Loess stratigraphic scheme. © 2015 Elsevier B.V.
Zhengtang Guo - One of the best experts on this subject based on the ideXlab platform.
-
clay mineralogy of the stari slankamen serbia Loess paleosol sequence during the last glacial cycle implications for dust provenance and interglacial climate
Quaternary Science Reviews, 2021Co-Authors: Qingzhen Hao, Slobodan B Markovic, Shuzhen Peng, Xinbo Gao, Long Han, Namier Namier, Wei Zhang, Milivoj B Gavrilov, Rastko Markovic, Zhengtang GuoAbstract:Abstract Clay minerals in Loess-paleosol sequences carry important information on dust source and the paleoenvironments of the areas of Loess distribution. The Loess-paleosol sequences in the Serbian part of the Carpathian Basin are among the most complete Quaternary terrestrial sedimentary sequences in Europe. However, relatively little is known about the origin and temporal variations of clay minerals in these deposits and their paleoclimatic implications. Here we present the results of high-resolution XRD clay mineral analysis of the Stari Slankamen Loess-paleosol sequence through the last glacial cycle. The roughly constant composition of the clay minerals within the Loess unit and most of the paleosol suggests that the clay minerals are of detrital origin and that pedogenic transformation has only occurred in the lower part of paleosol S1, which corresponds to the climatic optimum of Marine Isotope Stage (MIS) 5e. This provides a basis for addressing several important issues regarding the Carpathian Basin Loess, including its provenance, glacial dust activity, and the interglacial climate. The smectite-rich characteristic of the glacial Loess provides a diagnostic indicator for confirming local sources for the Carpathian Basin Loess deposits, and that these sources made little contribution to the dust deposited in Greenland during the last glacial. The first application of illite crystallinity and the chlorite ratio to the Carpathian Basin Loess-paleosol sequence suggests that they are more sensitive indicators than the clay mineral proxies previously used in European Loess studies. The enhanced precipitation during MIS 5e indicated by the new proxies and the transformation of clay mineral potentially provide new insights into understanding the regional climatic response to future global warming.
-
danube Loess stratigraphy towards a pan european Loess stratigraphic model
Earth-Science Reviews, 2015Co-Authors: Slobodan B Markovic, Urlich Hambach, Kathryn E Fitzsimmons, Bjorn Buggle, George Kukla, Thomas Stevens, Phil Gibbard, Michael Zech, Zhengtang GuoAbstract:The Danube River drainage basin is the second largest river catchment in Europe and contains a significant and extensive region of thick Loess deposits that preserve a record of a wide variety of recent and past environments. Indeed, the Danube River and tributaries may themselves be responsible for the transportation of large volumes of silt that ultimately drive Loess formation in the middle and lower reaches of this large catchment. However, this vast Loess province lacks a unified stratigraphic scheme. European Loess research started in the late 17th century in the Danube Basin with the work of Count Luigi Ferdinand Marsigli. Since that time numerous investigations provided the basis for the pioneering stratigraphic framework proposed initially by Kukla (1970, 1977) in his correlations of Loess with deep-sea sediments. Loess-palaeosol sequences in the middle and lower reaches of the Danube River basin were a key part of this framework and contain some of the longest and most complete continental climate records in Europe, covering more than the last million years. However, the very size of the Danube Loess belt and the large number of countries it covers presents a major limiting factor in developing a unified approach that enables continental scale analysis of the deposits. Local Loess-palaeosol stratigraphic schemes have been defined separately in different countries and the difficulties in correlating such schemes, which often change significantly with advances in age-dating, have limited the number of basin-wide studies. A unified basin-wide stratigraphic model would greatly alleviate these difficulties and facilitate research into the wider significance of these Loess records. Therefore we review the existing stratigraphic schemes and define a new Danube Basin wide Loess stratigraphy based around a synthetic type section of the Mosorin and Stari Slankamen sites in Serbia. We present a detailed comparison with the sedimentological and palaeoclimatic records preserved in sediments of the Chinese Loess Plateau, with the oxygen isotope records from deep-sea sediments, and with classic European Pleistocene stratigraphic subdivisions. The hierarchy of Danubian stratigraphic units is determined by climatically controlled environmental shifts, in a similar way to the Chinese Loess stratigraphic scheme. A new unified Danube Loess stratigraphic model has a number of advantages, including preventing confusion resulting from the use of multiple national schemes, a more transparent basis, and the potential to set Pleistocene palaeoenvironmental changes recorded in the Danube catchment area into a global context. The use of a very simple labelling system based on the well-established Chinese Loess scheme facilitates interpretation of palaeoenvironmental information reported from the Danube Basin Loess sites in a wider more accessible context that can be readily correlated world-wide. This stratigraphic approach also provides, for the first time, an appropriate framework for the development of an integrated, pan-European and potentially pan-Eurasian Loess stratigraphic scheme. © 2015 Elsevier B.V.
-
geochemical evidence for the provenance of middle pleistocene Loess deposits in southern china
Quaternary Science Reviews, 2010Co-Authors: Qingzhen Hao, Zhengtang Guo, Yansong Qiao, Frank OldfieldAbstract:The provenance of middle Pleistocene Loess in the middle and lower reaches of the Yangtze River, the most intensively investigated Loess deposits outside the Loess Plateau region in China, remains controversial. Identification of the provenance will provide crucial insight into the environmental implications of this valuable sedimentary archive, and into the potential role of the East Asian winter monsoon in transporting the dust from deserts in the Asian interior. In this study, geochemistry was used to compare the provenance of Loess in the lower reaches of the Yangtze River in southern China with that inferred for Loess deposits on the Loess Plateau in northern China. Compared with samples from the Loess Plateau, the <20 mm fraction in the Loess deposits of southern China has higher TiO2/Al2O3, Zr/Nb, Zr/Al, Zr/Ti, Zr/ Hf, Y/Al and LaN/SmN ratios, and lower Eu/Eu*, Th/Nb, Y/Nb and Al/Nb ratios. The clear distinction in immobile element ratios between samples from the two regions indicates that the Loess deposits in the two regions have different provenances. The inferred difference in source area is also supported by variations in the major element composition of bulk samples obtained in this study and collected from published data. These lines of evidence indicate that the deserts in the Asian interior are not the primary provenance for the southern Loess. It is suggested that the adjacent floodplains to the north of Yangtze River are the dominant dust sources, and the occurrence of sustained Loess deposits in the lower reaches of the Yangtze River, currently an area of northern subtropical climate, is an indication of local aridification and strengthened winter monsoon activity during glacial periods as a regional response to the Middle Pleistocene climate transition around 0.8 Ma. The role of the East Asian winter monsoon in transporting the dust from northern deserts to southern China has been overestimated in previous studies.
