Loess Strata Research Articles

Comparative analysis of the distribution and habitats of two <i>Eremias</i> species (Reptilia, Lacertidae) using niche-based GIS modeling

The distribution and habitat characteristics of two Eremias species ( E. arguta and E. stummeri ) from contiguous areas of southeastern Kazakhstan, northeastern Kyrgyzstan, and western Xinjiang, China, were analyzed using GIS modeling. We show that both species are dry-steppe-adapted xerophilous lizards with sclerophilic and partially petrophilic specialization. In spite of the visible similarity of the ecological niches (ENs) occupied by E. arguta and E. stummeri , the latter differs in a number of key variables. While most of the precipitation variables, the radiation of the winter and off-season months, and afternoon (PM) humidity are most important for E. arguta habitats, the habitats suitable for E. stummeri are limited by temperature variables, radiation during most of the year, and morning (AM) humidity. Differences on this scale indicate the way in which these lizards are adapted to different ecosystems — E. arguta to the plains and E. stummeri to the mountains — and support the views on their different zoogeographical accessory. A visible correspondence of the distributional pattern of the two Eremias species to the mountain piedmonts and low foothills, with Pliocene-Quaternary concreted pebble deposits and the loess strata, permit us to consider mountain trails as the most likely means by which the species expanded in the Late Cenozoic period. Pronounced isolation of the populations in the Northern and the Central Tien Shan intra-montane depressions appears as a factor from at least the Late Pliocene ( E. stummeri ) and the Middle Pleistocene ( E. arguta ) periods; and the association of the lizard habitats with loess deposits has given rise to the suggestion that there was an absence of serious change in their ranges during the Last Glacial Maximum (LGM). Low precipitation, a high annual temperature range and the high aridity of the climate in general beyond the ENM optimum of E. arguta all point to severe conditions for lizards surviving already in the eastern part of the Ily Basin and explain the limited species distribution in the highly arid deserts of Xinjiang. In terms of methodology, our data highlights the lack of a ‘generalized set’ of BIOCLIM parameters in the ecological niche modeling of the mountain species. In particular, moisture and solar radiation as well as the relief variables play an important role in the ecological health of the poikilothermic xerophilous species inhabiting mountain areas.

Physical modeling of wetting-induced collapse of shield tunneling in loess strata

The wetting-induced collapse of loess strata affects tunnel structures and is a key challenge in geotechnical engineering. In this study, we investigated the mechanisms that influence wetting-induced collapse/deformation of loess strata on the lining structure of a subway tunnel. First, a centrifugal field immersion unit and a monitoring system were developed based on the centrifuge working platform. The immersion device was composed of two sub-systems including a water supply system and a diffusion system. Subsequently, centrifugal model tests were performed under different wetting conditions to explore the impact of wetting-induced collapse of loess strata on the structure of the subway tunnel. The testing results showed that the non-uniform subsidence of the tunnel base induced by non-uniform wetting was the major cause of the collapse and deformation of the tunnel structure. The axial bending moment of the tunnel was found to be largest in the middle of the tunnel and decreased toward both ends. In addition, a layer of non-collapsible soil or properly treated collapsible soil with a certain thickness could effectively resist deformation induced by the subsidence of wetted loess. With an improved immersion simulation unit design and measurement device configuration, after being wetted, the pressure arch in the soil strata became weaker and gradually disappeared, resulting in a reduced range of the pressure arch on the side wall of the tunnel and complete elimination of the pressure arch effect on the top of the tunnel.

Structural Response of the Metro Tunnel under Local Dynamic Water Environment in Loess Strata

The reasons, prevention, and control of loess disaster are of great concern in practice. In recent years, Xi’an city, China, has taken the leadership in large-scale construction of subway lines in the loess strata. To study the structural response of the tunnel in loess region under local hydrodynamic environment, an experimental testing in 1g as well as a numerical simulation were performed, in which the achieved results were verified and were found to be in good agreement. Furthermore, the results showed that when the water outlet point is above the lining, the overall stress of the lining is “peanut shell,” as the water pressure of the outlet point decreases, the tensile stress of the top and bottom of the lining increases, while the compressive stress on both sides decreases; the channel form of the flow to the lining changes with the variation of the position of the water outlet point. It is worth mentioning that in the process of water gushing, the closer to the water source, the greater surface subsidence is, and there is a positive correlation between water pressure and surface subsidence. This study is of significant benchmark for the construction, maintenance, and prevention of tunnel in loess strata under the influence of water environment.

Load Characteristics of Tunnel Lining in Flooded Loess Strata considering Loess Structure

Loess has a unique structure and water sensitivity, and the immersion of loess leads to many tunnel lining problems in shallowly buried tunnels. Based on a tunnel in Gansu Province in China, two failure glide planes of a shallowly buried loess tunnel and their immersion modes are summarized. Finite element calculation of the structural Duncan‐Chang constitutive model is realized via the secondary development of finite element software, by which the loads on the secondary lining are calculated and verified in comparison with measured results. The load characteristics of the secondary lining are studied. The load evolution is closely related to the immersion position and scope of the load. After the loess near the failure glide plane of the arch foot is flooded, the load on the arch foot sharply increases. As the immersion expands, the maximum load moves from the arch end up to the hance. After the loess near the failure glide plane of the hance is flooded, the load on the hance decreases slightly. The stability of the overlying loess decreases gradually, which causes the loads on the vault and arch shoulder to rapidly increase. Additionally, the load distribution characteristics on the secondary lining are summarized.

Exploration of Deep Magnetite Deposit Under Thick and Conductive Overburden with Ex Component of SOTEM: A Case Study in China

In northern China, thick loess strata with low resistivity are widely present and can shield the deep induced electromagnetic field signal and influence the accuracy of deep targets while electromagnetic prospecting is being performed. To achieve deep target exploration with high resolution, a new technique known as the short offset transient electromagnetic method (SOTEM) is applied in this research area. This method can be used to perform near-source configuration surveys, but shows no obvious difference between the deep magnetite deposit and low-resistivity layer in this survey area. Therefore, it cannot explore the magnetite deposit directly using the traditional magnetic component (Hz) of SOTEM. The Ex component, which can more effectively distinguish the high-resistivity surrounding rock and overlying low-resistivity layer than the Hz component, is used for exploration. First, 2D forward modeling and sensitivity analysis of the high-resistivity body are carried out to determine the different responses of the Ex and Hz components, respectively. Moreover, to better determine the interface between the surrounding rock and low-resistivity layer, 1D Occam inversion and the generalized inverse matrix inversion method are used. Furthermore, aiming at the static effect of the Ex component in field exploration, joint inversion of the Ex and Hz components is carried out for comprehensive interpretation. Finally, a field test is conducted, and the drilling results are used for verification. The research results can provide an effective geophysical model for the exploration of contact metasomatic magnetite deposits.

Experimental Study on the Ratio of Similar Materials in Weak Surrounding Rock Based on Orthogonal Design

In the aspect of stability analysis of tunneling engineering, geomechanical model test is an important research method. A similar material is the prerequisite for the success of geomechanical model test. In the field of major engineering applications, a variety of similar materials are prepared for different geological conditions of surrounding rock and applied in some major engineering. With the use of standard sand, fine sand, and silt clay as materials, similar materials for weak surrounding rock were developed. Based on the orthogonal design method, through the direct shear test, the range analysis and variance analysis of various factors affecting the physical and mechanical parameters of weak surrounding rock are carried out. The results show similar material can meet the requirements in weak surrounding rock. Standard sand is the key factor that influences the internal friction angle of similar materials, and silt clay is the key factor affecting the cohesion of similar materials. Similar materials can meet the elastic modulus and severe requirements of the weak surrounding rock and can be used for the weak surrounding rock engineering. The new type of similar material configuration is widely used in shallow buried tunnel entrance section and urban shallow buried excavation engineering, in addition to tunnel engineering in loess stratum, and the problems of engineering design and construction are solved through geomechanical model test.

In-situ experimental research on water scouring of loess slopes

Frequent occurrence of landslides in the Chinese Loess Plateau has been influenced by the changes of water conditions. This paper, based on in-situ water scouring experiments under various slope gradients, cross-sectional discharge shapes and flow quantities, analyzed the rill flow information characteristics on a loess slope and its driving factors for anti-scourability of the loess stratum. The results show that the critical erosion slope gradient for the loess stratum (Q3) is about 24° and the mean erosion rate under half-round cross-sectional discharge is smaller than that under rectangular discharge. The relationship between flow quantity and mean erosion rate is linear and is positively correlated. Mechanical subsurface erosion was the primary condition responsible for water scouring on loess slopes because of stronger runoff channels such as vertical joints and large amounts of macro void caused by plants and animals. Loess anti-scourability is a significant issue to advance the research for soil and water conservation in the Loess Plateau of China.

Terrestrial mollusk records from Chinese loess sequences and changes in the East Asian monsoonal environment

The terrestrial mollusk fossils found in Chinese loess strata have been studied for over one hundred years. However, the greatest progress in these studies has been made only in the last two decades. In this paper, we review the advancements, advantages and limitations of terrestrial mollusk studies in Chinese loess deposits. Improvements in research methods and approaches have allowed the extraction of more detailed paleoenvironmental and paleoclimatic information from mollusk assemblages. The broadened research scope and content have yielded many new findings and results. The mollusk record has thus become one of the most important proxies in the paleoenvironmental and paleoclimatic reconstruction of loess-paleosol sequences in China. The greatest progress in the studies of terrestrial mollusks in Chinese loess sequences can be summarized as follows: (1) modern mollusk assemblages can be classified into four ecotypes, based on their temperature and humidity requirements, including eurytopic, semi-aridiphilous and sub-humidiphilous, cold-aridiphilous, and thermo-humidiphilous types; (2) Quaternary mollusk assemblages can be modified into the following three ecological types: glacial loess, interglacial paleosol, and interstadial weakly-developed paleosol assemblages; (3) mollusk records successfully reveal long-term climatic and environmental changes reflective of the history of East Asian monsoonal variations since the Late Cenozoic, and the succession of mollusk species also indicate short-term environmental changes such as millennial climate variability during Last Glacial Maximum and unstable climatic fluctuations during glacial and interglacial periods; and (4) more recently, new analytical approaches have offered increased research potential in areas such as paleotemperature reconstruction using the isotopic compositions of modern and fossil mollusk shells, combined with higher accuracy 14C dating of Quaternary loess deposits, which will greatly improve future loess paleoenvironmental research.

Centrifuge modelling of twin-tunnelling induced ground movements in loess strata

A great concern for the safety of large cross-section tunnels, which are being or to be built in the loess strata of China, is attracted. Generally, loess is a multi-phase porous medium and develops complex stress and strain variation while executing a tunnel project. Another problem is that the soil surrounding both tunnel arches is subjected to a complex loading due to the double excavation. To obtain an in-depth knowledge of the mechanism of tunnel deformation induced by the twin-tunnelling, we conducted comprehensive centrifuge tests, which can simulate and reproduce strictly the action process of twin-tunnelling. Through the model tests, the response of twin-tunnelling on loess stratum deformation was obtained. The investigations showed that with the increase of tunnel spacing, the stratum deformation distribution near the vault changes from a single-peak V shape to a double-peak W shape. Additionally, the height of the stratum pressure arch effect increases significantly. The settlement of the preceding tunnel is slightly larger than that of the latter tunnel, and the twin-tunnelling effect gradually decreases with the increase of tunnel spacing. Through comparative analysis of the different combinations of tunnel spacing and tunnel interval, the interaction between two tunnels with different spacing and interval during tunnelling was investigated, further optimizing the reasonable tunnel spacing and construction steps, as well as providing reference for tunnel route selection in the loess strata.

Taphonomic and paleoenvironmental issues of the Pleistocene loessic Paleolithic sites in the Qinling Mountains, central China

Abstract Hinterland intermountain basins and northern and southern piedmonts of the Qinling Mountains accumulated a large amount of loess during the Pleistocene. The loess strata not only record local paleogeographic and paleoenvironmental changes, but also contain rich hominin fossils and Paleolithic remains. In the northern piedmont of the Qinling Mountains and the lower valley of the South Luohe River, the loess strata have multi loess-paleosol sequences with aeolian loess continuously accumulating during glacial and interglacial cycles. In contrast to the northern piedmont, loess stratigraphy in the hinterland intermountain basins of the Qinling Mountains is relatively thin and contains finer loess particles. In this “mini” type of loess stratum, the density of Paleolithic remain generally is higher than the Loess Plateau in the north of the Qinling Mountains. Based on stratigraphic, chronological, and lithic artifacts analysis in recent years, it appears that the regional lithic assemblage belongs to the Oldowan (Mode I) lithic industry, and it is dominated by choppers, cores, flakes, and simple retouched flake tools from 1.15 to 0.6 Ma. Paleolithic open-air sites such as Gongwangling and Chenjiawo in the Lantian area, Shangbaichuan and Liuwan in the Luonan Basin, Qiaojiayao in the Lushi Basin, Longgangsi and Yaochangwan in the Hanzhong Basin, Guanmiao in the Ankang Basin, and the Yunxian Man Site in the Yunxian Basin are representative sites in the region; from 400 to 250 ka, the Longyadong cave site in the Luonan Basin inherited the characteristics of the local Mode I lithic industry, the stone assemblage is made up of cores, flakes, and small retouched flake tools, such as scrapers, points, and burins; during the period from 250 to 50 ka, bi-facially retouched Acheulean tools (Model II), such as hand-axes, picks, and cleavers, were commonly found in the Qinling Mountains region. The emergence of a large number of Model II artifacts indicates that local lithic industries went through a major transition process. Zhanghuokou, Guoyuan, and Huaishuping sites in the Luonan Basin, Diaozhai, Ganyu, Laochihe, and Xiehu sites in the Lantian area, Hejialiang site in the Hanzhong Basin are representative sites in this period; to the turn of the Late Pleistocene and Early Holocene, it may also exist a small flake-retouched tools lithic industry in the piedmonts of the northern and southern sides of the Qinling Mountains. The lithic assemblages in different stages of the Qinling Mountains region reflect the hominin behavioral changes and the development of lithic technology during the Pleistocene.

Landform-derived placement of electrical resistivity prospecting for paleotopography reconstruction in the loess landforms of China

The paleotopography of loess landform represents the initial surface before the evolution of the Aeolian depositional process. This paleotopography served as an indicator of the paleo-geography and erosion base that restrained the evolution of the current landform. In this case study, a landform-derived placement method involving electrical resistivity prospecting is proposed for paleotopography reconstruction. The method consists of extracting terrain feature knowledge and terrain feature-based paleotopography prospecting and reconstruction. The field experiment is validated and used in three typical loess landform areas in the Chinese Loess Plateau. These typical loess landforms include loess hill, loess ridge, and loess tableland. Terrain features considered include peaks, saddles, ridges, and gullies. The results show significant electrical resistivity difference between the paleotopography and loess strata. The electrical resistivity method could effectively detect the paleotopography and different loess layers. The reconstructed paleotopography using the feature-based method could effectively represent the morphology of the paleosurface compared to the result of the interpolation method. The reconstructed paleotopography also appears as a coincident terrain relief compared to modern topography; such a relief demonstrates significant landform inheritance between modern terrain and paleotopography. In the loess hill and ridge landform areas, the relative elevation difference of paleotopography is approximately 50m whereas that of the modern terrain is roughly 150m, indicating that the loess deposition process increased the topographic relief from paleotopography to modern terrain by approximately 100m. Similar altitude of the paleotopographic peaks (roughly 10m height difference) appears in the two nearby loess ridge and hill areas. The results indicate that paleo-geography of this area should be a landform of peneplain and almost a planation surface.

Model test on rainfall-induced loess–mudstone interfacial landslides in Qingshuihe, China

Loess–mudstone interfacial landslide is one of the most prominent landslide hazards that occurred in soil-rock contacting zones in the world. A semi-similar material physical model test was conducted to investigate the startup conditions and sliding mechanism of rainfall-induced loess–mudstone interfacial landslides based on the landslides which occurred in Qingshuihe county, Inner Mongolia Autonomous Region, China. When rainwater infiltrates downward along loess strata and gradually gathers near the interface, the soil strata near the interface are softened, causing frictional constraint reduction. The mudstone strata serve as an aquifuge between underlying mudstone and overlying loess strata due to different permeability coefficients. As rainfall continues, the softened zone is expanded and gradually developed into fluidization, ultimately leading to interfacial landslide. This instability process is studied and reproduced experimentally through a self-designed physical model test in this paper. The model test results indicate that startup conditions of interfacial landslides are related to rainfall intensity and duration as well as thickness of overlying loess strata. This study also indicates that the more the impact is from the rock at the back of the slope, the more likely an interfacial landslide is to occur. But this is not a decisive factor to induce the interfacial landslide. The gradient of slope is also a potential factor to induce interfacial landslide. When the gradient exceeds 24°, the cutting layer landslide is likely to occur because impact of gravity is greater than that of interface friction resistance. This study, exploring startup conditions and the sliding mechanism of rainfall-induced loess–mudstone interfacial landslides, provides a scientific guidance for the prevention, monitoring, early warning, and control for geologic landslide hazards.

Study on Failure Mechanism and Stability of Loess Slope in Huangshui River Basin

This paper shows the result of the research on the stability of loess high slopes with 30m and 80m in Huangshui River basin. The investigations carried out the numerical simulations of the slope stability based on the drilling and sequence sampling test in a typical loess stratum of the survey region. The result shows that the mechanisms of fracture related to the gradients of slopes are different and the limit equilibrium angles of slopes are 60° and 37° respectively.

Analysis and Research on Construction Technology of Air Return Inclined Shaft Crossing Formation on Special Conditions

The sectional area of air return inclined shaft 1 in Hecaogou coal mine is 20.7m2 and the dip angle is 20°. It belongs to the large angle and section inclined shaft. The soil of mining area has the characteristics of loose, poor stability and integrity, low compressive strength, easy to be in the rheological and pulverization. After the first support in hidden digging section of air return inclined shaft 1, the soft and collapsible loess strata turned into the shape of silly putty because of the construction disturbance, which caused serious deformation and subsidence to that shaft. We succeed to pass the extra thick soft and collapsible loess strata and obtain the expected effect the by means of analyzing deformation principle of surrounding rock on shaft and grouting reinforcement of rail pile and advanced support of exploration of thread steel and metal wedge and comprehensive technology of using stone to take the place of the floor loess. It has reference significance to the other shaft and drift construction with the similar formation condition

Quartz OSL dating of last glacial sand dunes near Lanzhou on the western Chinese Loess Plateau: A comparison between different granulometric fractions

Optically stimulated luminescence (OSL) dating technique is a reliable method to determine the ages of sand dune sediments. While it seems logical to assume that for these windblown materials (such as sand dune sediments) grains from different sized fractions are suitable for optical dating and would yield identical ages, this was not previously explicitly demonstrated yet. In this study, six samples were selected from the sand dunes intercalated in loess strata near Lanzhou, western Chinese Loess Plateau, and different grain-size quartz fractions (e.g. 38–63 μm, 90–150 μm, 150–200 μm, 200–250 μm and 250–300 μm) were extracted to compare the OSL ages of different grain-size quartz. The results show that: (1) quartz OSL ages derived from different grain-size fractions produce identical ages within errors, confirming that the ages resulting from both coarse silt-sized (or middle grain of 38–63 μm) and sand-sized (90–300 μm) quartz can represent the periods of sand dune accumulation; (2) the OSL ages of the selected sand dune samples fall into ca. 28–18 ka, suggesting that the sand dune accumulation occurred during the marine isotope stage 2 (MIS 2) in current study area, which might imply regional increased aridity on the western Chinese Loess Plateau.

Terrestrial mollusc records from Xifeng and Luochuan L9 loess strata and their implications for paleoclimatic evolution in the Chinese Loess Plateau during marine Oxygen Isotope Stages 24-22

Abstract. Marine Isotope Stages 24-22 is a key period of the Mid-Pleistocene Transition, however, its climate variability is still unclear. The coarse-grained loess unit L9, one of the most prominent units in the Chinese loess stratigraphy, yields a high potential terrestrial record of paleoclimatic and paleoenvironmental changes during this period. In this study, two high-resolution terrestrial mollusc records of L9 loess strata from the Xifeng and Luochuan sequences in the Chinese Loess Plateau were analysed. Our mollusc results show that the MIS 24, the early and late parts of MIS 22 were dominated by cold and dry climate. Relatively mild-humid climate occurred in MIS 23 and the middle part of MIS 22. The climatic conditions at Xifeng region were cooler and more unstable compared to Luochuan region. A comparison of mollusc species composition and other proxies of L9 strata (MIS 24-22) with those of L1 loess units (MIS 4-2) indicates that the L9 loess was not deposited under the most severe glacial conditions in Quaternary climate history as suggested in previous studies. Our study shows that climatic conditions in the Loess Plateau during the L9 loess forming period were similar to that of gentle glacials (MIS 24 and MIS 22) and interglacial (MIS 23), as suggested by the marine δ18O record. Three cooling fluctuations occurred at ~930 ka, 900 ka and 880 ka, which might hint to the global "900 ka cooling event". The "900-ka event" in the Loess Plateau does not seem to be a simple long glaciation, but rather several complex climatic fluctuations superposed on a general cooling trend. The uplift of the Tibetan Plateau and the general cooling experienced by the Earth during this period may have resulted in abundant dust sources and increased dust transport capability, as indicated by increased grain size and the mass accumulation rate of L9 loess.

Palaeodunes intercalated in loess strata from the western Chinese Loess Plateau: Timing and palaeoclimatic implications

Dune systems represent important palaeoenvironmental archives and therefore provide valuable information on past climate conditions of dryland regions. This study reports on several palaeodunes (thickness ca. 10–20 m) intercalated in thick loess accumulations, located in the Lanzhou area of the western Chinese Loess Plateau. The intercalated dune sands are well-sorted and have a typical aeolian dune structure, with distinct cross-bedded sand layers. The chronology for these palaeodunes and the related loess sediments was established by quartz optically stimulated luminescence (OSL) dating of 19 samples. The dating results indicate that sand dune accumulation occurred at ca. 35–25 ka, which implies a period of increased aridity during dune formation. This interpretation is in contrast to previously retrieved data from lake archives of the nearby deserts (e.g. Tengger and Badain Jaran desert), indicating a humid episode during marine isotope stage 3 (MIS 3). The previously proposed humid MIS 3a may not be universal over all of northwest China.

Spatial distribution and stratigraphic characteristics of surface sediments in Taihu Lake, China

A geophysical survey was carried out for Taihu Lake, one of the largest shallow lakes in China. The StrataBox™ Marine Geophysical Instrument was applied for the first time to obtain high-resolution seismic data (in the form of vectorgraphs) of the lake sediment. Data were then interpreted by SonarWiz.Map acoustics software. Data were correlated with core stratigraphy from the lake as well as an outcrop on the northern side of the lake at Yao Bay. Results show that the upper 10 m sediment (beneath the interface of the sediment and the overlying lake water) is characterized by laminated sediments, which can be classified into two stratal types, i.e. lacustrine sediment stratum (U1) and underlying hard loess stratum (U2). The contact of these two lithologies is not continuous, and part of it is absent in the lake basin. Unequally spread over the lake basin, the lacustrine sediment (mainly consisting of sludge and muddy-clay) is found in areas along the western bank, to the northwest of the Xishan Mountains and along the northwestern side of the lake. In the rest of the lake basin, the hard loess stratum is exposed in outcrops. The depth of the lacustrine sediment ranges from 1 to 2 m, while the depth of the sludge (closely related to the modern lacustrine environment) varies from 0.03 to 1.0 m. The spatial distribution of lacustrine sediments in Taihu Lake is primarily influenced by transportation and sedimentation of riverine materials, as well as the hydrodynamics of lake currents.

Cyclic variability in microstructure and physio-mechanical properties of the Xiashu Loess–palaeosol sequence in Nanjing, China

For the Xiashu loess–palaeosol sequence in Nanjing, China, further to our work on the cyclic variability in its chemical composition and swelling-shrinkage properties [Xia, J., Huang, G.L., Liu, Z. T., Chen, X.M., 2007. Cyclic variability in chemical composition and swelling–shrinkage properties of the Xiashu loess stratum near Nanjing, China. Pedosphere 17 (5), 666–672.], this paper studies the cyclic variability in its microstructure and physico-mechanical properties and the corresponding influence on its engineering behaviour for geotechnical and geological practices. In addition, the cyclic variability in the soil's grain-size distribution and geochemical characteristics is compared with that of the loess–palaeosol sequences at two other sites in China, indicating a geographical pattern of cyclic variation of the sequences.

Pedogenetic dating of loess strata

Loess is an aeolian Pleistocene sediment of periglacial or arid origins, deposited without internal stratification in parcels representing geological periods. The contents of total as well as individual carbonates are comparatively uniform within a specific stratum, but the relative carbonate contents differ significantly between the various glacials as represented by loess facies. There is a consistent increase in the content of dolomite with decreasing age of stratigraphic units, which has traditionally been attributed to postdepositional alteration, notably the gradual removal of the calcite fraction by weathering. The explanation of pedogenetic enrichment in the course of aeolian recycling of glacial and glacio-fluvial deposits could convincingly account for the stepped profile of the dolomite's depth functions. The implication is that such recycled sediments can be attributed to specific cryocratic phases simply by their characteristic dolomite fraction, i.e. they can be dated. In order to test this hypothesis against the competing weathering hypothesis, strata of the Gudenus Cave in Lower Austria were subjected to carbonate differentiation analysis. The results are presented, analyzed and discussed. It is shown that the dolomite contents of the unweathered strata provide a clear trend that is even more pronounced than that found at open-air sites.