Aeolian Sand Research Articles

Transformation of soil and plant pastures cover of light chestnut soils in to sandy soils of kochubey biosphere station

The transformation of the vegetation cover of pasture landscapes is the result of the interaction of climatic, ecological, physiological and anthropogenic environmental factors. The result of the dependence of the conservation of species in the vegetation cover, especially forage plants, on the influence of these factors and the determination of their variability and stability in pasture ecosystem communities is relevant for production and science. As a result of a long-term study (more than 10 years) of the soil and vegetation cover of pasture landscapes on different soils and sands of the Kochubey Biosphere Station (KBS), especially under the conditions of anthropogenic impact, it was revealed that weeds adapt well to new conditions, stable populations of non-forage plants are created, causing deflation and degradation. The floristic composition and ecological and coenotic characteristics of the dominant plant species were studied on light chestnut sandy loamy soils and sands. The rapid change of indigenous species of plant communities formed in the conditions of a continental climate indicates a high mobility of vegetation. The species diversity and occurrence of plant species characterize the qualitative difference between the compared soils (light chestnut, sandy loam and sand). The described syntaxa reflect the directions of natural and anthropogenic transformation of the vegetation of light chestnut soils and sandy massifs of the KBS, which are characterized by a change in the composition of the prevailing life forms, a decrease in the role of valuable forage plant species and an increase in the diversity of annual non-forage species, without changing their species diversity. The landscape dynamics of the KBS territory is expressed in the transformation of the relief and vegetation cover under the influence of eolian processes with an increase in the projective cover and overgrowth of mobile landforms of sand massifs.

Effect of spatial and temporal “drought legacy” on dust sources in adjacent ecoregions

AbstractDrought affects the occurrence and intensity of aeolian dust events in many ecoregions. This study investigated the effects of “drought legacy” (the cumulative temporal persistence of drought's consequences on the earth system) on dust generation, a topic which had not previously been evaluated. We investigated the potential dust/drought legacy relationship in the USA's Southern Great Plains and Chihuahuan Desert ecoregions over 14 years, including the 2011–2012 extreme drought, at spatial distances up to 100 km around dust point sources and for up to 5 years' drought history. At every temporal and spatial scale, drought levels associated with dust initiation points in the two ecoregions were significantly different. Chihuahuan Desert dust sources concentrated in areas of severe to extreme drought, while those in the Southern Great Plains, which experiences greater land use, spanned wider ranges of drought conditions. At short temporal scales of drought (1 week and 1 year), dust initiation in the Chihuahuan Desert was associated strongly with severe to exceptional drought conditions at all spatial extents, while Southern Great Plains dust sources were linked to lower drought intensities. For longer drought histories (the past 2 and 5 years), Chihuahuan Desert dust sources were connected with moderate to severe drought, while Southern Great Plains dust sources were linked to moderate drought, at all spatial extents. Drought's legacies, extending over multiple years and kilometer scales, are shown to have roles in subsequent dust events at regional scales, though they can be regionally modulated by land use practices and ecosystem characteristics.

Periodic Bedrock Ridges at Oxia Planum and Chryse Planitia, Mars: Evidence for widespread aeolian erosion of an ancient surface by regional paleowinds

Periodic Bedrock Ridges (PBRs) are repeating, symmetrical, wind-transverse, bedrock-abraded linear ridges that occur on Mars as parallel sets. Here, we extend our previous survey of PBRs at Oxia Planum – the landing site of ESA's ExoMars Rosalind Franklin rover – to include three additional sites along the margins of the circum-Chryse basin to understand patterns in PBR orientation and occurrence. We analyzed PBR crestline orientation at each study site and found them to be consistent across this large region, but their orientations do not align with global circulation model winds, suggesting contemporary winds are not responsible for PBR development. Furthermore, we used observations of landscape-level stratigraphic relationships at Oxia Planum to constrain the formation age of PBRs to be late Noachian to early Amazonian. Their consistent orientations and age suggest that the Chryse-margin PBRs formed concurrently and represent modification of an ancient palaeosurface. In addition, we find a tendency for PBRs to preferentially occur in regions where Fe/Mg-rich phyllosilicate minerals were detected in hyperspectral remote sensing data. We conclude that regional scale aeolian processes formed the circum-Chryse PBRs, and that exposed bedrock with Fe/Mg-rich phyllosilicate detections were either more susceptible to PBR formation, or better preserve PBRs than other regional lithologies.

Numerical Simulation of Heat Transfer of Porous Rock Layers in Cold Sandy Regions

The heat transfer characteristics of porous rock layers (PRLs) have significant seasonal differences. This feature has been used to protect the permafrost subgrade under highways and railways from degeneration. However, in cold sandy environments, the transformation law of heat transfer characteristics of PRLs on account of climate warming and aeolian sand filling needs to be solved. This work developed a coupled heat transfer model for the soil–PRL system aimed at analyzing the convective heat transfer process and mechanism of a closed PRL. Furthermore, the impact of climate warming and sand filling on the cooling performance of the PRL under different mean annual air temperatures (MAATs) of −3.5, −4.5, and −5.5 °C was quantified. The numerical results indicated that the natural convection of the closed PRL occurred only in winter, and the effective convective height of the rock layer decreased with the sand-filling thickness. As the thickness of sand filling increased, the critical temperature difference for the occurrence of natural convection increased, accompanied by decreases in the Rayleigh number, the duration, and intensity of natural convection. When the sand-filling thickness exceeded 80 cm, natural convection would not occur in the PRL. Under a warming scenario of 0.052 °C·a−1, the cooling performance of the PRL could offset the adverse impact of climate warming and raise the permafrost table in the first 20 years. Moreover, the closed PRL can be more effective in permafrost regions with colder MAATs. For cold sandy permafrost zones, sand-control measures should be taken to maintain the long-term cooling performance of the PRL. This study is of great significance in guiding porous rock embankment design and road maintenance along the Qinghai–Tibetan Railway.

Mineralogy of Recent Sediments of Al-Teeb River Basin-East Missan Governorate, Southeastern Iraq

This research aims to define the mineralogical composition of recent sediments that were deposited around the Al-Teeb River basin in the east Missan Governorate and try to determine the provenance or the source of these sediments. The study area represents the southeastern edge of the Mesopotamian Plain and is part of it. 15 samples were collected from eight stations of recent sediment that was deposited around the Al-Teeb River; two field works are covered (December 2019 and August 2021). Mineralogical study of the sediment after separating the light and heavy minerals by heavy liquid Bromoform in order to determine the mineralogical composition of the studied samples by using the petrographic microscope the light mineral fraction composed (95.5%) of the total mineralogy. The light components of these sediments consist mainly of quartz about 25.31%, feldspars (potash and plagioclase feldspar) about 9.53%, sedimentary rock fragments (carbonate rock fragments up to 33.39%, chert rock fragments 7.65%, evaporates fragments, 7.31%), (igneous rock fragments, and metamorphic rock fragments about 6.94%). The major component of the heavy minerals residue is opaque minerals with a range of 36.76% and non-opaque minerals with a range of 63.24%. The non-opaque minerals are mainly of chlorite 7.42%, pyroxenes composed of both orthopyroxene and clinopyroxene 6.37%, amphiboles composed of hornblende, glaucophane, and tremolite 7.02%, (mica: biotite and muscovite) 9.81%, zircon 7.54%, tourmaline 5.1%, epidote group 5.91%, rutile 4.5%, kyanite 2.2%. The sediments have two types of stability: moderately stable and ultra-stable. The mineralogical composition shows that the major sources of these sediments are; the river terraces and flood plain of the river in the Mesopotamian Plain, another source of these sediments is the aeolian deposits that separated from sand dune fields in the studied area, and outcrops of ancient sedimentary formations in the southeastern of Iraq as specified by the incidence of the carbonate rock fragments.

Trade-offs in growth and reproduction of rhizomatous clonal plant Phragmites communis in response to aeolian processes

Abstract Trade-offs in growth and reproduction are essential parts of the adaptive strategies of clonal plants. How rhizomatous psammophytes respond to aeolian processes (sand burial and wind erosion) by means of trade-offs is supposed to be especially important for their colonization on the active sand dune. Despite partial documentation of the responses of rhizomatous species to aeolian processes, how these clonal species respond to aeolian processes by means of potential trade-offs in growth and reproduction still remains unclear. In this study, we employed field investigation and biomass modeling to evaluate the trade-offs between vegetative and reproductive growth as well as between the number and size of ramets of Phragmites communis in response to sand burial and wind erosion. Sand burial enhanced the accumulation of seed biomass and reproductive effort. Wind erosion reduced reproductive effort but had no significant influence on seed biomass. Sand burial increased the biomass of ramets, while wind erosion increased ramet population density and accelerated ramet maturation. Our results demonstrate that rhizomatous psammophytes adjust their growth strategies in response to aeolian processes, i.e. reproductive growth and ramet size increase in response to sand burial, while vegetative growth and ramet numbers increase in response to wind erosion.

Shrinking Desert Channel Response to Increasing Human Interferences and Changing Natural Factors in the Upper Yellow River

Many rivers are tightly coupled and intersected with aeolian sand dunes, whose geomorphological evolution involves not only fluvial processes but also aeolian processes that pose a new challenge to fluvial geomorphological studies. However, due to few field studies, our overall understanding of the desert channel geomorphic process is limited. In this paper, we present an outstanding example of desert river channel evolution regulated by aeolian–fluvial interactions in the Ulan Buh Desert of the Yellow River, based on a long time series data set (1966–2019) of channel cross-sections. The results indicate that the lateral addition of aeolian sand, the water–sediment relationship and human interference have a significant role at different periods of channel evolution. Before 1986, higher discharge, lower sediment content and greater intensity of aeolian activity caused aeolian–fluvial interactions and a relative scouring and silting balance in the channel, with little human activity. From 1986 to 2000, an increase in large reservoir operation, vegetation coverage and floodplain farming, coupled with water–sediment relationship variation, caused rapid deposition and shrinkage of the river channel. From 2000 to 2014, the channel kept a slight scouring state. With Haibowan reservoir operation beginning in 2014, the talweg experienced rapid scouring and undercut rebound. However, an expanding and stable floodplain accelerated sedimentation on the floodplain and weakened river lateral erosion, indicating that the channel has shown a shrinkage trend. Meanwhile, wavelet analysis results indicate that human interferences and aeolian activities have no significant role in the periodical characteristics of the channel’s longitudinal erosion and deposition. Therefore, on the whole, increasing human interferences and decreasing wind dynamics have driven this desert wandering channel to be stable, and to gradually form a new balance between erosion and sedimentation.

Eocene dry eolian system in the Jianchuan Basin, southeastern Tibetan Plateau: Implications for regional wind regime and paleoclimate

East Asia experienced a climatic transition from a zonal pattern (climate zones defined by latitude) to a monsoon-dominated pattern during the Cenozoic. However, hitherto little consideration has been paid to the atmospheric circulation of the planetary wind system that prevailed during the early uplift of the Tibetan Plateau, due to the lack of reliable proxies. Here, we conduct a study on the eolian successions from the Eocene Baoxiangsi Formation in the Jianchuan Basin, southeastern Tibetan Plateau to reconstruct regional atmospheric circulation and paleoclimate. Two facies associations are recognized in the eolian deposits of the Baoxiangsi Formation: a dominant eolian dune association and a subordinate interdune association. Eolian dune deposits are characterized by large-scale cross-stratified sets of strata composed internally of packages of grainflow, wind-ripple strata and pinstripe lamination. These packages of laminae and cross-stratified eolian dune sets are bounded internally by superimposition and reactivation surfaces and interdune surfaces, respectively. Interdune deposits are uncommon and composed dominantly of subcritical climbing translatent strata to form sets of strata and these are themselves bounded by interdune surfaces to form cosets of strata. The association of dominant eolian dune deposits, widely distributed interdune surfaces of great lateral extent (> 450 m) and that climb at a shallow but positive angle (< 1°) is consistent with the climbing dry eolian system. The commonly occurring superimposition surfaces indicate the presence of compound dunes (megadunes, draas). Based on the analysis of 715 dip–azimuth readings of foresets of eolian cross-beds, we reconstruct the prevailing wind directions: the paleowind in the northern basin flowed toward the northeast; in the southern basin it flowed toward the southwest. This wind regime indicates that the Jianchuan Basin was located at the zonal boundary between the westerlies and the trade winds, and the construction of the dry eolian system was controlled by the subtropical high-pressure belt during the middle–late Eocene. Following the accumulation of the dry eolian system, a monsoon climate regime gradually established itself and prevailed in the Yunnan Province; this expanded northward over time. This was closely related to the uplift of the central Tibetan Plateau and the retreat of the Paratethys ocean in the late Eocene.

Ecological improvement of takyric solonetz in northern China using modified ridge cultivation with drip irrigation

AbstractSoil salinization is one of the most important forms of land degradation in drylands of the world. As a typical type of saline‐sodic soil, takyric solonetz seriously jeopardizes the living environment of the inhabitants with severe consequences for regional ecology, agriculture, and the aeolian dust dynamics. Improving the vegetation and ecology status of takyric solonetz is essential but challenging because of its extremely drought conditions with low saturated hydraulic conductivities (ks &lt;0.1 mm/day). Here, we conducted a three‐year field experiment by three‐stage drip irrigation to regulate the water and salt levels of the soil and improved ridge cultivation through sand as a water dispersal media strip for takyric solonetz in northern China. Results showed that the planting ridge was desalted after 3‐year treatments of drip irrigation. The electrical conductivity of a saturated soil paste extract reduced from 21.28 and 13.38 to below 3.00 dS/m, indicating a decrease of 91.50% and 88.50% in the 0–40 cm and 0–120 cm soil layers, respectively. The pH of the soil paste extract decreased from 11.13 to 9.78 in the 0–120 cm soil layer. The survival rate of the willow saplings planted for a shelterbelt was 91.60%. The height, diameter at breast height, and ground diameter of the willow increased slowly to 84.60 cm, 1.20 mm, and 2.02 mm in the first 2 years, respectively, but increased rapidly to 121.90 cm, 7.48 mm, and 12.02 mm, respectively, in the third year. Our treatment also substantially changed the understory vegetation status, in terms of vegetation coverage (89%), number of species (18), and density (600 plant m−2). The dominant plant family in the vegetation community shifted from the Amaranthaceae to the Poaceae. This study provides and validates a new technology for ecological improvement of takyric solonetz, supporting a theoretical and practical approach for ecosystem and vegetation improvement in takyric solonetz in the future.

The role of abrasion and resident fines in dust production from aeolian sands as measured by the Portable in situ Wind Erosion Laboratory (PI-SWERL)

Aeolian deposits are important sources of atmospheric dust, particularly from extensive dune fields, interdune areas and vast sand sheet deposits across the globe. This study quantified the total suspended particle flux (TSP), particulate matter <10 μm (PM10) and PM2.5 emissions with the Portable in situ Wind Erosion Laboratory (PI-SWERL) for eighteen different types of sand to determine the role of aeolian abrasion in dust production. Aeolian abrasion results in grain coating removal, chipping, and spalling of sand grains during saltation transport, producing dust-sized particles. The studied sands were poorly- to well-sorted, round to angular, coarse to fine sand composed of quartz-rich to gypsum-rich particles. Some sand samples contained up to 14 % silt and clay, referred to as resident fines. Experiments on sand with diverse characteristics elucidated dust production processes. Samples composed of 100 % sand produced dust by aeolian abrasion with fluxes of 0.2–2.5 mg m−2 s−1 indicating aeolian abrasion as a potentially important process contributing to dust storms and desert loess deposits. Sand containing resident fines produced up to 42 mg m−2 s−1, an order of magnitude more dust than clean sand samples, with >60 % of the dust produced by the release of silt and clay and up to 40 % from aeolian abrasion. These high fluxes rival dust storms emanating from playas like Owens Lake in California. Climate change and anthropogenic disturbance of stabilized aeolian sand deposits in arid lands will likely result in increased dust emissions in the future which should be parameterized in climate models.

Investigation of Small Strain Dynamics in Modified Aeolian Sand under Vibration Triaxial Conditions

By utilizing vibration triaxial tests, this study analyzed the effects of various factors, such as confining pressure, consolidation ratio, and silt content on the elastic modulus and damping ratio of silt-modified aeolian sand under conditions of minor deformation. The results indicate that with increasing confining pressure and consolidation ratio, the dynamic elastic modulus of improved aeolian sand gradually increases, while the damping ratio decreases progressively. The dynamic elastic modulus growth rate of untreated aeolian sand demonstrates a positive correlation with confining pressure, while the corresponding rate for the modified aeolian sand by adding cement and silt exhibits an inverse correlation with confining pressure. As dynamic strain increases, the dynamic elastic modulus decreases and approaches a stable value. The damping ratio rises at a diminishing rate and eventually stabilizes as dynamic strain continues to increase. The dynamic stress-strain backbone curve of the modified aeolian sand follows a theoretical hyperbolic model, while the small strain dynamic behavior is consistent with the Hardin-Drnevich model.

Record of aeolian processes in Pleistocene deposits in the foreland of the European sand belt

Abstract This article presents the degree of aeolization of Pleistocene deposits in the foreground of the European sand belt in southern Poland. Ten of the 13 sites were established in the Oświęcim Basin and three in the south part of the Silesian Upland. Attention was focused on four types of deposits formed during three glaciations (Sanian, Odranian, Vistulian): boulder clay, fluvioglacial sands and gravels, end moraine deposits, and aeolian sands. Quartz grain abrasion (for the 0.8–1.0 mm fraction) was examined by mechanical graniformametry and the morphoscopic method. The record of aeolian processes in analyzed deposits is the presence of quartz grains RM (very well-rounded and mat) and EM/RM (moderately rounded and mat). They were found in deposits of various origins and ages but in variable proportions. Considering only the average percentage of grains RM, it should be regarded that abrasion of deposits is low in the case of fluvioglacial deposits, moderate in the case of glacial deposits, and good in the case of aeolian deposits. However, the key factor in determining the degree of abrasion is the share of EM/RM grains, which in the abovementioned deposits are seven, three, and twice as many as RM grains. Therefore, the most noteworthy research result is the very high total share of grains with aeolian abrasion (RM + EM/RM), amounting on average to 84.1% for Odranian fluvioglacial deposits, 86.7% for Sanian glacial deposits and 92.6% for Late Glacial aeolian deposits. It means that in the study area, glacial and fluvioglacial transport included deposits with good aeolian abrasion obtained in the periglacial environment before the transgression of the ice sheets. Probably due to the longer persistence of periglacial conditions in southern Poland, compared to its central and northern parts, the degree of aeolization of fluvioglacial and glacial deposits is better. At the same time, there is a significant differentiation in the aeolization of fluvioglacial deposits within the outwash plain in the foreland of the maximum extent of the Odranian ice sheet. In its proximal part, near the front of the ice sheet, fluvioglacial deposits are characterized by much worse abrasion of quartz grains than in the distal part.

Long‐Term Landscape Evolution in Response to Climate Change, Ecosystem Dynamics, and Fire in a Basaltic Catchment on the Colorado Plateau

AbstractPredicting responses of semi‐arid to montane landscapes in southwestern North America to ongoing anthropogenic changes requires understanding of past interplay among geomorphic, ecologic, and climatic factors. This study utilizes modern weathering and sediment transport processes to inform the interpretation of a 250‐kyr lacustrine sediment record of paleoecology, hydrology, and erosion from a small, closed basin, basaltic catchment on the southwestern edge of the Colorado Plateau. Geochemical and mineralogical analyses of bedrock, colluvium, and lake sediments indicate that clastic sediments in the basin are a mixture of local physical weathering products (albite and ilmenite) and eolian dust (quartz, illite, and zircon). Dust fractions increase during glacial periods coincident with lower overall sedimentation rates, suggesting this pattern results from decreased local erosion rates and not increased dust deposition. Titanium counts from X‐ray fluorescence core scanning, a proxy for ilmenite content, traces past local erosion rates. The highest erosion rates, inferred from the highest Ti counts, follow climatic transitions toward interglacial conditions (Marine Isotope Stage 5e, 3a, and the Holocene), periods characterized by vegetation changeover (observed in the core's palynology), higher temperatures (piñon‐juniper‐oak pollen abundance), lower effective precipitation (shallow lake facies), and increased wildfire activity (microscopic charcoal particle counts and sizes). While brief inferred episodes of erosion occur following abrupt transitions to cooler and wetter conditions, indicated by the abundance of subalpine tree (spruce and fir) pollen and deeper lake facies, landscapes appear more stable during glacial periods. This long‐term perspective suggests that aridification and resulting vegetation succession and increased wildfires will increase erosion rates in similar settings regionwide.

An Auto-Detection and classification algorithm for identification of sand dunes based on remote sensing images

Dunes are among the most abundant aeolian landforms found on Earth and other planets. The automatic mapping of dunes over large-scale areas is crucial for predicting, monitoring, and managing lands threatened by sand encroachment. However, the spectral similarity between dune and inter-dune areas, as well as the diverse presentations of dunes of the same type, have made it challenging to automatically classify and map dunes. In this study, we propose a two-step 'detect-then-classify' framework that enables the automatic identification of heterogeneous dune types. The first step involves dune detection. We introduce a newly developed convolutional neural network called SandUnet, which is adapted from Attention U-Net. This network is designed to preserve uncompressed input signals ensuring that minor differences in the color and texture of the dunes are retained. The second step focuses on dune-type classification. To classify dunes, a fine-tuned MobileNet was constructed to integrate the wealth of knowledge ingrained in MobileNet's pre-trained layers with the adaptations tailored specifically for the sand dune images. Subsequently, each dune image is automatically classified into six different types using this framework. By applying this framework to all the bare sand areas of the Taklamakan (or Taklimakan) Desert using Landsat-8 imagery, the final classification of dune types of the desert was achieved. Testing on randomly selected 10% image patches of whole desert, the overall accuracy of the dune-type classification is 70%. This study presents an automatic and economical solution for identifying dunes in large-scale areas.

Weathering Saharan dust beyond the Spanish Mediterranean Basin: An interdisciplinary dialogue

This interdisciplinary dialogue draws on climatology and cultural studies to explore the phenomenon of “Saharan dust” that passes through and beyond the Spanish Mediterranean Basin. The dialogic process seeks to unearth the power relations within which weather stories and the authors are always already entangled, with a view to re-imagining weather writing and climatic storytelling in decolonial terms. Our parallel inquiries trace how origin stories, material mobilities, atmospheres, and environmental regulation work to codify the aeolian dust as an intrusion across borders. Drawing on critical theory, we argue that this weather “from” the Sahara Desert is othered in Eurocentric weather narratives, mapping onto geopolitical logic of “Fortress Europe”. Our research is instructed by postcolonial thought, political ecology, and the speculative feminist position of weathering. Through critical engagement with science in context, we dwell lastly on African air quality and experiences of weathering atmospheric dust further upwind. Our concluding comments speculatively drift with Mediterranean winds to animate a positionality of middleness.

Aeolian Sediment Transport Responses to Vegetation Cover Change: Effects of Sampling Error on Model Uncertainty

AbstractAlthough it is widely known that observations of aeolian sediment transport are susceptible to large sampling errors, sample designs are frequently used that do not sufficiently reduce the measurement uncertainties inherent in the study of aeolian processes. Here, we examine the influence of sample size (n) and sampling location on uncertainty in models of aeolian sediment transport responses to vegetation cover change. We compare measurements from a stratified random array of 27 horizontal sediment mass flux samplers to vegetative cover data collected at a 1 ha site over a period of nearly 6 years. To assess the sensitivity of modeled relationships between aeolian transport and vegetative cover to sample design, we analyze statistical regressions for all possible combinations of sample size and sampler locations. We show that at least 17 randomly located samplers are needed to consistently capture the sediment mass flux response to vegetative cover change. We found that multiple statistically significant models can describe the sediment flux‐vegetative cover relationship when using smaller sample sizes, demonstrating the risks of inferring sediment transport response from an underpowered sample design. Across vegetative functional groups, we found that woody cover generally influenced aeolian sediment transport rates more than herbaceous cover, while model uncertainty at large sample sizes (n &gt; 17) showed the limitation of using vegetative cover as an indicator of aeolian sediment transport. Our results suggest an evaluation of sampling practices in aeolian sediment transport studies may be needed to avoid inferential errors that are likely pervasive in this field of study.

Dust deposition in agricultural landscapes: Temporal and spatial dynamics along a transect into a natural forest patch

This work presents the results of the deposition rate of aeolian sediments within a forest patch of semiarid Argentina. The goal of this study was to evaluate the spatial and temporal dynamic of the dust deposition rate (Dr), mainly of the mineral fraction. Passive collectors were installed along transects in a forest patch at 5, 15, 25, 50, 100 and 300 m downwind from the border of an agricultural plot. The average Dr during 30 months was 38.3 ± 26.8 g m−2 yr−1. Dr was statistically similar between spring-summer (47.5 ± 30.1 g m−2 yr−1) and the autumn–winter period (29.2 ± 21.7 g m−2 yr−1). The mean diameter of sediment particles was higher in spring-summer (70 µm) than in autumn–winter (50 µm), probably due to the greater contribution of coarser sediments from wind erosion of surrounding agricultural soils (local source) during spring-summer. During both periods silt-sized particles (40 %) and very fine sand (20 %) were the most abundant, while clay content was 3.5 %. Clay and silt contents were higher in autumn–winter, while fine sand content was higher in spring-summer. Dr within the forest patch was highly variable, therefore statistically homogeneous, despite the fact that 300 m inside the forest the average Dr was ≈35 % lower than at 5 m from the agricultural plot. Sediment deposited at the forest border showed higher aggregation than the sediment collected inside the forest. Forest patches are capable of retaining particles that are key for the soil fertility of semiarid areas, highlighting the importance of aeolian source-sink processes and of forest patches for long-term management decisions in agricultural landscapes.

Study on the deterioration characteristics of aeolian sand concrete under the coupling effect of multiple factors in harsh environments.

This study takes the aeolian sand concrete as a research object, uses the relative dynamic elastic modulus to study its macro characteristics, and combines nuclear magnetic resonance、scanning electron microscope to study its pore characteristics and micro morphology under the action of prestress, freeze-thaw and salt intrusion. The results show that with the increase of the amount of aeolian sand, the dynamic elastic modulus of aeolian sand concrete shows a pattern of first decreasing, then increasing, and then decreasing; when no prestress is applied, the porosity of aeolian sand concrete first increases, then decreases, and then continues to increase. Among them, the porosity of aeolian sand concrete with a 40% content of aeolian sand decreases by 0.06% compared to that with a 0% content of aeolian sand, and decreases by 0.003% compared to that with a 60% content of aeolian sand; with the increase of prestress, the porosity of aeolian sand concrete with the same amount of aeolian sand increases gradually with the increase of damage degree. The porosity of concrete with 40% aeolian sand content increases by 0.33% when the damage degree is 0.0 compared to 0.3, with a 6.31% increase in the number of multi damage pores; under the coupling effect of multiple factors, when the amount of aeolian sand is 40%, the damage degree of the four groups of aeolian sand concrete before and after the coupling effect is 0.0, 0.1, 0.2, and 0.3, respectively, increases by 25.8%, 32.2%, 73.8%, and 85.8%, respectively; under the coupling effect of multiple factors, the content of aeolian sand is 60%, the damage degree is 0.2 and 0.3 groups, and the content of aeolian sand is 20%, the damage degree is 0.3 groups, which does not meet the standard requirements; under the coupling action of stress, freeze-thaw, salt intrusion and the amount of aeolian sand, the filling effect of aeolian sand on the internal pores of aeolian sand concrete decreases first, then increases, and then decreases with the increase of the amount of aeolian sand. The filling effect is further weakened after the action of stress. After the superposition of freeze-thaw and salt intrusion, the coupling effect of water and salt solution in frost heaving medium makes the variation law and range of physical and chemical characteristics of aeolian sand concrete show a great difference.

The Cretaceous palaeodesert of the Sanfranciscana Basin (SE Brazil): A key record to track dissolved evaporites in the West Gondwana

Extensive palaeodeserts are known from the intracontinental basins of South American Platform, simultaneously to volcanic activity and thick salt beds developed during the rifting phase of Brazilian coastal basins. Based on palaeoenvironmental conditions and modern analogues, it would be expected that Cretaceous evaporites were frequently described in the intracontinental basins of West Gondwana, however, such deposits are rarely mentioned. This work evaluated the recognition and role of evaporitic-related features as palaeoclimatic/palaeoenvironmental proxies, through outcrop-based facies, X-ray diffraction and petrographic analyses of the Areado Group (Lower Cretaceous), Sanfranciscana Basin, southeastern Brazil. The Areado Group stands out as a remarkable record of evaporitic-siliciclastic interactions, consisting of alluvial, lacustrine and aeolian deposits. The stacking pattern reflects the progressive drying-up of the Sanfranciscana Basin during Cretaceous times. Regardless salt dissolution, the Areado Group comprises pseudomorphs after evaporites, evaporitic moulds, sand patch-fabric, and replication of the microtopography of efflorescent crusts. Preservation of evaporitic features in the Areado Group was controlled by the unique geological context of the Sanfranciscana Basin, which was submitted to syndepositional/eodiagenetic cementation and pseudomorphism, along with rapid burial caused by the progradation of aeolian dunes. Equivalent sedimentary structures and morphological aspects also occur in other Cretaceous palaeodeserts of intracontinental basins throughout Brazil. Timing of salt dissolution and isovolumetric/non-isolumetric replacement are important controlling factors on the geological record of evaporitic-siliciclastic systems that undergo post-depositional modifications. The database provided here indicates that playa lake deposits are commonest than traditionally represented in the non-marine Cretaceous record of the West Gondwana and other similar settings worldwide.

Aeolian–lacustrine margins: implications for carbon capture and storage within the Rotliegend Group, Southern North Sea

The Southern North Sea Basins of the United Kingdom were renowned for their hydrocarbon resources and exploited extensively from the 1960s to the 1990s. The Permian Leman Sandstone in particular formed an excellent reservoir due to its extensive clean aeolian sediments and was subsequently explored for decades, resulting in a wealth of subsurface data that are now widely accessible. The strata of the Leman Sandstone comprises mixed continental deposits from aeolian, fluvial and lacustrine environments which interfinger with the saline lake deposits of the Silverpit Formation. With the potential reassessment of depleted gas reservoirs in the North Sea for use as sequestration targets for captured carbon dioxide, there is significant renewed interest in the reservoir geology of the Leman Sandstone. A regional study of the sedimentology and petrophysical properties of the Leman Sandstone and Silverpit formations within quadrants 43, 44, 48 and 49 of the Southern North Sea has been conducted. Multiple interactions between the depositional environments are observed, resulting in a complex interplay between aeolian and lacustrine transgressive/regressive events, and migration and expansion/contraction of the fluvial system. In wireline petrophysical data, each depositional environment, along with their transitional environments, form relatively distinct clusters that can be used as a predictive tool for reservoir interpretation in the absence of core, despite extensive sediment recycling between environments.