Aeolian Sand Research Articles

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.

Modern periglacial eolian deposits and landforms in the Søndre Strømfjord area, West Greenland and their palaeoenvironmental implications

Modern fluvio glacial sediments in two east-west oriented valleys between Søndre Strømfjord Air Base and the Inland Ice (West Greenland) are partly redeposited by eolian activity. Topographic barriers have induced an areal distinction between sandy and silty eolian sediments. Morphological and sedimentological investigations enable a facies analysis of these rare, active cold-climate eolian deposits and a comparison with the extensive Pleistocene sand sheets and loess deposits of Europe.
 Eolian processes are active throughout the year in a dry cold-climate environment. Accumulation of eolian material on the eolian sand sheets and silt covers mainly takes place in summer, whereas deflation and redeposition is dominant in winter. Meteorological conditions (especially thickness of snow cover) may prevent eolian activity.
 The vegetation on the sand sheets adapts itself to the intensity of the eolian activity. Vegetation is scarce in the low areas near the active flood plains where deflation is intensive, whereas the downwind depositional areas are more densely vegetated. Only a few species play an active role in the formation of small phytogenic dunes, which are characterized by a low preservation potential. Similar conditions are envisaged for the extensive Pleistocene sand seas of northwestern Europe.
 A characteristic sedimentary sequence occurs in downwind, upslope direction. Fluvio-eolian deposits on and near the active flood plain are characterized by horizontally bedded eolian sand interbedded with fluvial deposits. The latter are partly winnowed by eolian activity leading to inversely graded lamination. Horizontal bedding of fine-medium grained sand interbedded with thin coarse-grained strata is the proximal facies of cold-climate eolian sand sheets. Within-bed structures are dominated by plane bed lamination. A more homogeneous (fine-medium grained) horizontally bedded sediment, comparable to that dominating in the extensive Pleistocene sand sheets, represents the distal facies of these sand sheets.
 The uplands are covered by eolian silt deposits. These are coarser than 'typical' loess and lack other loess characteristics. This is explained by the local source area and the short transport distance. These 'proximal loess' deposits are mainly deposited on the windward side of the valley walls due to blocking of dust-laden airflows by these topographic barriers. The primary micro-lamination in these deposits may also have been present in the Pleistocene loess deposits.

Tracing provenance of eolian sands in the northern Ulan Buh Desert, China: Evidence from the REE geochemical characteristics

Desertification is a primary threat to crop farming, the livestock industry, and the eco-environment in northwestern China. Through field research and satellite imagery, it has been discovered that there are 4–5 sand belts in the shape of handclasps connecting major deserts in the Alxa Plateau region of northern China. These sand belts have been expanding for several decades. However, eolian sand transport between major deserts through these expanding sand belts is still underestimated. Identifying the source areas of eolian sands in deserts provide essential knowledge to prevent desertification. In this study, we collected samples from the northern Ulan Buh Desert (UBD), the Yamalik Desert (YD), and the Langshan Mountains and analyzed their REE contents in the <125 μm fraction. We compared REE geochemical characteristics of fine-grained sands in the UBD with other recently published REE data for potential source areas. Our findings indicate that the primary origins of fine-grained sands in the northern UBD are from the Qilian Mountains (QM) and Badain Jaran Desert (BJD), which are transported through the YD. Contributions from the Gobi-Altay Mountains to the north are relatively minor. The Langshan Mountains and Hawula Mountains are not considered as the primary sources of fine-grained sands in the UBD. In contrast, surface sediments in the southern UBD have a local mixture of the paleo-lacustrine deposits, the Gobi sediments, and minor external inputs from the BJD and QM. Our findings demonstrate that sand belts connecting these deserts play a crucial role in the eolian transport of fine-grained sands. Therefore, both the Chinese government and scientists should pay close attention to them in future efforts to combat desertification.

Comparative study on cavernous weathering features formed by coastal processes and acidic alteration: Implications for rounded pits on Martian rocks

Surface images taken by rovers and landers show the existence of rounded pits with diameter of centimeters on Martian rock surfaces. These pits seem to be similar to terrestrial cavernous weathering features, generated by salt weathering (e.g., alveoli), or by stream flow erosion (e.g., potholes), found near coastal areas. Alternatively, if the weathered rocks contained carbonate minerals, the pits might have been formed by acidic weathering. Here, we compare geomorphology of cavernous weathering features formed by coastal processes on Earth and by laboratory experiments simulating acidic weathering of carbonate. Our field observations for coastal areas of the Japanese islands show that a high cavity number density and small cavities characterize cavernous features formed by salt weathering as compared with those formed by stream flow. Our experimental results show that acidic weathering can generate cavernous features, with high number densities and small diameters. Based on principal component analysis, cavernous weathering features formed by salt weathering, stream flow, and acidic alteration can be distinguished mainly by the number density and diameter. By applying our approach to Martian rocks, we find that the morphological characteristics of rounded pits on Jezero Crater rocks are different from the above cavernous weathering features, and that the Martian pits are categorized as being intermediate between cavernous features formed by salt weathering and acidic weathering. If the pits on Jezero Crater rocks were formed by salt weathering, salt weathering on Mars could have been less effective (possibly, due to a difference in water salinity or salt composition) than those found in coastal areas of Earth. Alternatively, these Martian pits might be formed by other processes (e.g., vesicles in volcanic breccia, eolian processes, or freeze-thaw cycles of porewater).

Impermeability and Durability of Self-Compacting Concrete Prepared with Aeolian Sand and Recycled Coarse Aggregate

Impermeability and Durability of Self-Compacting Concrete Prepared with Aeolian Sand and Recycled Coarse Aggregate

Study on the Attenuation of Long-Term Skid Resistance of Asphalt Mixtures under Aeolian Sand Conditions

In this work, the long-term skid resistance attenuation law of asphalt mixtures in the presence of aeolian sand was studied. Four types of asphalt mixtures underwent skid resistance abrasion tests using an accelerated loading tester. The pendulum value (BPN) and structure depth (MTD) of these four mixtures were determined under various conditions of sand density and abrasion times. The correlation between the BPN and density and the number of times of abrasion were investigated, respectively, to analyze the skid resistance attenuation law at the microscopic and macroscopic levels. Our results indicate that the skid resistance of the four types of asphalt mixtures initially decreased and subsequently reached a stable state. Sand density primarily influences skid resistance during the initial stage, while the number of abrasions becomes the dominant factor affecting skid resistance in the later stages.

Wind erosion after steppe conversion in Kazakhstan

Semi-arid regions of Central Asia suffer from wind erosion due to expanding steppe conversion and unsustainable farming practices. Empirical data from field observations are needed to support the implementation of adapted management. In this study, a mobile wind tunnel was used for the first time in Kazakhstan to assess the soil's erodibility under real conditions. Field experiments were conducted on loamy sands with different initial conditions that are typical for the most erosive time of the year: a bare surface with a cloddy structure after recent steppe conversion, a weak crust on a plot with barley (Hordeum vulgare L.), and a plot with loose material in the rows of maize plants (Zea mays L.). Subsequently, different levels of mechanical stress (low, moderate, high) were considered to analyze the effect of disruptive forces soils experience during field cultivation (light cultivator, disc harrow, tractor tires) on possible soil losses. The results of wind tunnel experiments showed already great differences under initial conditions. The cloddy structure of the recent steppe conservation had the lowest susceptibility against wind erosion due to a good aggregation and a large roughness, resulting in soil loss of 12 g m−2. The plot grown with barley was less affected by wind erosion due to the weak crust, smaller distances between plants, and leaves close to the ground (soil loss of 34 g m−2). Maize was also the most problematic crop in the study area because wind can blow below the plant canopy without considerable resistance during the early growth stages. Additionally, existing deposits in the maize rows from previous erosion events led to the highest soil loss of 1609 g m−2. Mechanical stress by seedbed preparation generally increased the erodible fraction, resulting in higher soil losses (light cultivator: 198 ± 129 g m−2, disc harrow: 388 ± 258 g m−2). The most severe disruption of soil structure occurred on tractor tire tracks, causing a loss of 2767 ± 1810 g m−2. Consequently, the pulverizing effect of tractor tires on dry soil must be considered a serious emission source. Comparing the soil organic carbon content of topsoil and eroded material showed that organic carbon was enriched only in the aeolian sediments of the recently converted plot (+69%). We conclude that soils after steppe conversion need to be treated with particular care from the very beginning so that severe events from the past are not repeated.

Aeolian dust movement and deposition under local atmospheric circulation in a desert-oasis transition zone of the northeastern Taklimakan desert

Taklimakan Desert, in the northwest China, is one of the main sources of dust storms in the world. Frequent dust storms have seriously affected the ecological environment of surrounding oases. Quantification of dust deposition on the different underlying surface is vital to understand the local atmospheric cycling and its effect on movement of the dust particles in desert fringe areas. To examine the contribution of airflow from different direction to the dust deposition rate, the desert–oasis transition zone between the Korla oasis and the northeast edge of the Taklimakan desert is selected as the study area. 36 h backward trajectories of air masses arriving at the study site from 1st March to 31st May 2023, were determined by using the HYSPLIT (Hybrid Single Particle Lagrangian Integrated Trajectory Model) model. The trajectories were categorized by k-means clustering into 3 clusters, which show distinct features in terms of the trajectory origins and the entry direction to the site. Dust collection tank were placed on five underlying surfaces from south to north: shifting sand desert, semi-shifting sand desert, desert vegetation, shelter forestland and croplands at the height of 0.2 m, 0.5 m, and 1.5 m. At the each of height, four dust collection tanks were arranged to collect the dust from 4 directions. Results show that, air masses from the south with highest frequency (46 days) and highest dust storm occurrence (91.3 %) is the main contributor of dust particles to the study area. Dust deposition rate on different underlying surfaces showed a significant decreasing trend from the desert to oasis, and the dust deposition on all underlying surfaces decreased with the height. Dust deposition corresponding to the southward wind direction is the highest, and the amount of fine dust particles are increased with the height of the dust collection tank. The results of this study could be helpful to forecast the potential occurrence and mowing pathway of dust storms, which can provide the basis for mitigation of the negative effects on the environment.

Aeolian dust and hydro-biological characteristics: Decoding dust storm impacts on phytoplankton in the northern Arabian Gulf

Aeolian dust is an essential source of growth-limiting nutrients for marine phytoplankton. Despite being at the core of the Global Dust Belt, the response of the Arabian Gulf ecosystem to such atmospheric forcing is rarely documented. Here, the hydro-biological effect of mineral dust was studied in the northern Arabian Gulf (NAG) off Kuwait through monthly water sampling (December 2020 to December 2021), dust-storm follow-up sampling, and mineral dust and nutrient addition in-situ experiments. The multivariate analysis of oceanographic data revealed pronounced hydro-biological seasonality. The mineral dust deposition during two severe dust storm events in March and June 2021 showed a spatially varying effect of dust on coastal waters. The dust storms elevated the surface dissolved iron levels by several magnitudes, increased the dissolved inorganic nitrogen and phosphorous levels, changed their stoichiometry, and offset the hydrobiological seasonality. In the microcosms, dust input temporarily reduced phytoplankton phosphorous limitation in a dose-dependent manner when mesozooplankton (copepods) grazing was minimal. The microphytoplankton response to mineral dust inputs was comparable to that with nitrogen and phosphorous treatment. While Both treatments increased diatom size structure and biomass, the abundance of single-celled diatoms was comparatively higher in dust treatment. Multivariate analysis indicated that dust deposition alters the hydrographical properties of the surface ocean during dust storm events. The effects, though transient, were traceable for 3–16 days post-storm in coastal waters. The response of the summer phytoplankton to these changes, if delayed or muted, should be interpreted with caution given the summer water column stratification, the high nitrogen: phosphorous ratio and the low phosphorous solubility of aerosol dust, and the complex pelagic microbial food web interactions in the NAG. This study thus underlines the importance of a multivariate approach in documenting the ecological implications of Aeolian dust storms on marine environments closer to the dust source regions.

Westerly aridity in the western Tarim Basin driven by global cooling since the mid-Pleistocene transition

To explore the relationship between the global cooling, westerlies, and central Asian aridity, we report ∼1.1 Ma local sedimentary environment changes according to physical-chemical parameters from an 800-m core (KT11) from the Kashgar region in the western Tarim Basin, China. Grain size end-member (EM) modelling is employed to quantify the processes of sediment transport and deposition. Four end members with modal values of 272 μm, 144 μm, 45.6 μm and 12.7 μm were extracted and explained 97.9% of the variance in the grain size data, corresponding aeolian dynamics, river energies, delta development and pedogenesis/long-term suspension components transported by wind or water, respectively. Four dominant sedimentation types, including lacustrine facies, delta facies, fluvial facies, and aeolian dunes, were identified through lithology and grain size frequency curves. The 1.1 Ma sedimentary successions experienced delta deposits interbedded with fluvial and aeolian deposits and lacustrines (1.1–0.6 Ma), alternating fluvial and aeolian facies with the occurrence of deltas and lacustrines (0.6–0.15 Ma), and aeolian facies interbedded with deltas and fluvial facies (0.15 Ma-present). Stepwise drying sedimentary conditions and enhanced desertification indicated by increasing rubidium/strontium ratios and proportion of aeolian sands, and decreasing total organic carbon since the past 1.1 Ma, implied intensified westerlies, likely resulted from ice volume expansion and ongoing global cooling according to geological record comparison and simulations during the Last Glacial Maximum compared to preindustrial conditions, which may have controlled the expansion of the permanent deserts in inland Asia. These persistent drying trends and intensified westerly circulation in arid regions during glacial periods after the mid-Pleistocene Transition indicated by larger amplitudes of aeolian sand proportion than prior to 0.6 Ma are similar to those in the interior monsoonal Asia, where the larger-amplitude of median grain size indicated enhanced Asian winter monsoon intensity and drier glacials.

Grey correlation analysis of macro- and micro-scale properties of aeolian sand concrete under the salt freezing effect

To study the effect of the pore structure of aeolian sand concrete (ASC) with different compositions on its compressive strength in a freeze-thaw environment, ASC with 0% (S0), 25% (S25), 50% (S50), 75% (S75), and 100% (S100) of aeolian sand (AS) content was prepared in our experiment. The damage and degradation laws of the compressive strength of ASC cube in the presence of chloride freeze-thaw were studied, and the compressive strengths of S0, S50 and S100 were predicted from the pore structure parameters. Compressive strength, nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) tests of the ASC samples were carried out. Grey correlation analysis was used to analyze the correlation between the pore structure parameters and the compressive strength, and a model was developed to predict the compressive strength of S0, S50 and S100 ASC subjected to freeze-thaw cycles (FTCs). It was shown that ASC with 25% AS content showed a large improvement in compressive strength, which was 6.86% higher than that of the S0 group. With the progression of FTCs, the porosity of ASC increases, and the bound fluid saturation and the proportion of 0–0.1 µm pores decrease. According to the grey correlation analysis, the saturation of bound fluid and the proportion of 0–0.1 µm pores have the strongest correlation with the compressive strength of ASC. The joint prediction model for the compression strength has a correlation coefficient of 0.937, and is able to better predict the compressive strength of ASC at different AS replacement rates during the FTCs.

Effect of temperature-rising inhibitor on the hydration and performance of cemented paste-filling material

The addition of a temperature-rising inhibitor (TRI) to aeolian sand paste materials (ASPM) to produce paste-like filling mining materials can solve multiple problems. First, it may alleviate the environmental problems caused by solid waste treatment in mines to achieve sustainable use of solid waste. Second, It may solve the problem of rapid temperature rise in mines caused by the rapid heat release during filling body hydration. Therefore, this study explored the hydration of an ASPM with different TRI contents and its mechanical properties, setting time, and microstructure. The results show that at TRI contents of 0–1.0%, the peak heat-release rate of the ASPM is reduced by 16.0%, the early hydration heat release is reduced by 14.2%, and the delay of the heat-release peak is more prominent. TRI inhibits the hydration of ASPM primarily within 7 d, which reduces the early strength of the ASPM by a maximum of 43.4%. However, with the increase in age, the strength difference gradually decreases, and TRI even becomes beneficial for the development of strength in later stages. In addition, the high content of TRI has a significant retarding effect on ASPM hydration. The temperature rise test shows that TRI can reduce the temperature increase rate and delay the peak temperature increase rate, which can effectively solve the problem of concentrated heat release by backfill. This paper provides a theoretical basis for the application of TRIs in cemented paste backfill.

Experimental Investigation into the Proportion of Cemented Aeolian Sand-Coal Gangue-Fly Ash Backfill on Mechanical and Rheological Properties

Aiming at the problems of large water secretion, poor suspensibility and low strength of cemented aeolian sand (AS)-fly ash (FA) backfill (CAFB) mixtures, CAFB was doped with fine coal gangue (CG) particles crushed to less than 4 mm and configured as cemented aeolian sand-coal gangue-fly ash backfill (CACFB) mixtures, in which coal gangue accounted for 8% of the mass ratio of the slurry. Through UCS and rheological experiments, using the response surface methodology and an orthogonal design, the following conclusions were drawn: (1) With the increase in ordinary Portland cement (PO) and slurry concentration, the UCS of the CACFB increased. (2) With the increase in the FA dosage, the UCS of the CACFB decreased first and then increased due to the gradual increase in FA dosage, destroying the reasonable ratio of the material and leading to the reduction in the material’s UCS, and with the growth in time, the volcanic ash effect of the FA caused the UCS of the material to increase. (3) With the increases in slurry concentration, the yield stress and viscosity coefficient of the slurry increased. (4) Reasonable proportions for CACFB should ensure the strength characteristics and rheological properties of the material. Through theoretical and experimental research, the final reasonable proportions were as follows: the concentrations of slurry, AS, CG, FA and PO were 77.5%, 42%, 8%, 17.5% and 10%, respectively. This ensured that the UCSs of the CACFB at 3 d, 7 d and 28 d were 1.2 MPa, 2.5 MPa and 4.3 MPa, respectively; the yield stress of the CACFB was 495 Pa, and the viscosity coefficient was 3.97 Pa·s. These reasonable proportions of the CACFB can meet the strength index and flow property of material industrial experiments.

Aeolian bedrock ridges in Gale crater, Mars

Fields of parallel, regularly-spaced, bedrock ridges observed on Mars and rarely on Earth have been interpreted as aeolian surface features oriented perpendicular to a formative wind. The exact formation process for these ridges, however, including the role of aeolian erosion versus deposition, continues to be debated. We identified forty fields of bedrock ridges on and within the sedimentary strata of Gale crater's central mound, Aeolis Mons. To better constrain the development of these landforms and the winds responsible for their formation, we characterized ridge morphology, orientation, geographic distribution, stratigraphic relationships, and interactions with other aeolian landforms. The study area of Aeolis Mons was chosen to leverage the extensive high-resolution image coverage from orbit, as well as to build upon the detailed stratigraphy compiled from in situ exploration with the Mars Science Laboratory Curiosity rover. Using the orientation of the ridges, we present a wind vector map of Aeolis Mons. The orientation of bedrock ridges in the Mound Skirting Unit, which unconformably drapes Aeolis Mons, suggests the average wind direction in Gale crater may have remained consistent since that unit was emplaced (∼3.8–3.1 Ga). This study explores the implications of these ridges for the history of wind, deposition, and erosion in Gale crater.

Impact of dust deposition on the growth of marine autotrophic and heterotrophic microorganisms: Evidence from the South China Sea

Aeolian dust can provide nutrients for the ocean and affect the growth of phytoplankton. However, the impacts of dust deposition on autotrophic and heterotrophic microorganisms have rarely been studied. In this study, we conducted two microcosm experiments in the low-nutrient and low-chlorophyll environment of the South China Sea and found that dust did not stimulate the abundance of autotrophic and heterotrophic microorganisms. Our results show that dust contains most of the unreacted iron-bearing minerals, and thus provides limited bioavailable iron and nitrogen for bacterioplankton and phytoplankton growth. These results elucidate the overlooked impacts of the properties of the iron-bearing minerals in aeolian dust on microbial communities, which may play an important role in marine ecosystems and climate change.

Progress and prospects for research on Martian topographic features and typical landform identification

The study of Martian surface topography is important for understanding the geological evolution of Mars and revealing the spatial differentiation of the Martian landscape. Identifying typical landform units is a fundamental task when studying the origin and evolution of Mars and provides important information for landing on and exploring Mars, as well as estimating the age of the Martian surface and inferring the evolution of the Earth’s environment. In this paper, we first investigate Mars exploration, data acquisition and mapping, and the classification methods of Martian landforms. Then, the identification of several typical Martian landform types, such as aeolian landforms, fluvial landforms, and impact landforms, is shown in detail. Finally, the prospects of Mars data acquisition, landform mapping, and the construction and identification of the Martian landform classification system are presented. The construction of the Martian landform classification system and the identification of typical Martian landforms using deep learning are important development directions in planetary science.

The relationship between pore structure and strength of aeolian sand concrete under low temperature

To examine the relationship between microscopic parameters and compressive strength of aeolian sand concrete (ASC) at low temperatures, the compressive strength of ASC at different temperatures is predicted by factors such as the pore structure parameters and the ambient temperature. The experiments used 100 % replacement of river sand (RS) with aeolian sand (AS) to prepare fully ASC, and regular concrete with the same water-cement ratio as the control group. The experiment used nuclear magnetic resonance (NMR) technology and grey correlation analysis method to analyze the microscopic parameters and compressive strength of concrete specimens with three curing ages of 7d, 28d, and 60d at temperatures of 20 °C, 0 °C, −5 °C, −10 °C, −15 °C, and −20 °C. It was shown that the agglomeration between the fine particles during the mixing process results in a large number of pores in the interior of the ASC, resulting in a larger porosity compared to ordinary concrete. As a result, its compressive strength was lower than that of ordinary concrete, and the loose and porous internal structure provides room for the filling of more ice crystals. Therefore, the increase in compressive strength of ASC at different curing ages in an environment of −20 °C was greater than that of ordinary concrete. Among them, at-20 °C, the compressive strength of ASC with curing ages of 7d, 28d and 60d increased by 6.31 %, 3.59 % and 3.97 % respectively compared with ordinary concrete. Finally, a predictive model between parameters such as temperature, porosity, mean pore size distribution and gel content and compressive strength was developed, which was highly accurate.

Multi‐Year Tracing of Spatial and Temporal Dynamics of Post‐Fire Aeolian Sediment Transport Using Rare Earth Elements Provide Insights Into Grassland Management

AbstractAeolian sediment transport occurs as a function of, and with feedback to ecosystem changes and disturbances. Many desert grasslands are undergoing rapid changes in vegetation, including the encroachment of woody plants, which alters fire regimes and in turn can change the spatial and temporal patterns of aeolian sediment transport. We investigated aeolian sediment transport and spatial distribution of sediment in the surface soil for 7 years following a prescribed fire using a multiple rare earth element (REE) tracer‐based approach in a shrub‐encroached desert grassland in the northern Chihuahuan desert. Results indicate that even though the aeolian horizontal sediment mass flux increased approximately three‐fold in the first windy season in the burned areas compared to control areas, there were no significant differences after three windy seasons. The soil surface of bare microsites was the major contributor of aeolian sediments in unburned areas (87%), while the shrub microsites contributed the least (&lt;2%) during the observation period. However, after the prescribed fire, the contribution of aeolian sediments from shrub microsites increased considerably (∼40%), indicating post‐fire microsite‐scale sediment redistribution. The findings of this study, which is the first to use multiple REE tracers for multi‐year analysis of the spatial and temporal dynamics of aeolian sediment transport, illustrate how disturbance by prescribed fire can influence aeolian processes and alters dryland soil geomorphology in which distinct soils develop over time at very fine spatial scales of individual plants.

The effect of depositional environment on sustaining a carbon storage site

One of the most difficult challenges facing planet earth is climate change caused by an increase in the concentration of greenhouse gases. Increased effort is being placed on delineating and characterizing suitable geologic formations that can house these gases. As part of this effort, we studied how the depositional environment would influence the storage of CO2 in the Illinois Basin. Lithofacies of the Mt. Simon Formation within the Illinois Basin were interpreted from the core data available for one of the four wells. The lithofacies interpreted from the core data were correlated with the motifs of the gamma-ray (GR) log in order to synchronize the information. Based on the lithofacies from the core and GR log, the depositional environment was defined. This was further used to establish a stratigraphic correlation across the four wells. Petrophysical analysis was carried out to evaluate the suitability of the rock properties in storing CO2. Structural features such as faults were interpreted on the 3D seismic data to evaluate the sealing capacity of the Mt. Simon Formation. A conceptual model of the depositional environment was developed and integrated with the rock properties using sequential Gaussian simulation. CO2 gas was injected and simulated in the Mt. Simon geologic model to evaluate how the flow would be impacted by the formation's depositional environment over time. Based on the lithofacies interpreted from the geologic core data and GR log, four depositional environments were interpreted — a braided river system, a fluvial deposit, a flood plain/shallow ephemeral environment, and eolian deposits. The structural framework revealed that the lower section of the Mt. Simon Formation is laterally extensive and structurally controlled. This allows CO2 gas to be evenly distributed throughout the formation.