Sand Sheets Research Articles

Evaluation of Suitability of Sand Sheet as Sand Filters for Water Treatment, West Al-Sharqat Area, Iraq

The main objective of this study to assess the properties of Sand sheet in Al- Sharqat City, Iraq, to determine their suitability to be used as water filters. Five stations (1, 2, 3, 4 and 5) were selected according to the variation in the lithological properties, gradation and accessibility to the materials source. Laboratory tests included grain size analysis, water content, specific gravity and chemical analysis. Tests results showed that the moisture content, specific gravity, gypsum content, total dissolved salt, organic matter content, and pH ranged from 0.90 to 5.48%, 2.63 to 2.66, 2.16 to 14.68%, 4.21 to 20.21, 3.81 to 9.41%, and 7.77 to 8.01, respectively. The test results vary due to a variety of factors such as sampling depth, secondary gypsum content, and so on. The results showed, according to Indian standard 1993 and Iraqi typical standard (1555 in 2000), the sand sheets in the study area are not appropriate as water filters.

Fluvial-aeolian interaction deposits in the Andean Foreland basin (Northwest Argentina): Architecture and facies model

• Multiscale analysis of an aeolian-fluvial interaction field. • Work field analysis and GPR images were used for medium-scale analysis. • Granulometric and microscopy interpretation were used for medium and small scale. • An architectural model was proposed using all these methods. • Fluvial-aeolian interaction deposits are divided into dry, intermediate, and wet. The fluvial-aeolian interaction field of the Guandacol valley (northwest Argentina) is studied through different methodologies that comprise satellite, drone and GPR images, bedform descriptions, and grain-size analysis. The obtained information allowed the recognition of five depositional subenvironments: 1. Dune patches; 2. Aeolian sand sheets; 3. Muddy plains; 4. Active channels; and 5. Abandoned and secondary channels. Moreover, the lithofacies pattern, sedimentary structures and geometry of the beds permitted the definition of ten architectural elements in both channel and interchannel areas. The channel architectural elements comprise active channels with intercalations of aeolian deposits (CHe), abandoned or secondary channels (CHa), aeolian sand ramp (CHsr), lateral bars (CHlb), and aeolian mesoforms (CHem). The architectural elements in the interchannel area include active dunes (Fad), fixed or low-migration rate dunes (Fsd), partially flooded interdunes (Ffd), sandy flats (Fsf), and muddy plains (Fmp). A model of the evolution of fluvial-aeolian interaction environment is proposed in which three types are recognized: dry, intermediate, and wet. Migratory dunes and sand sheets environments dominate the dry interaction systems in the floodplain (Fad, Fsf). At the same time, during the intermediate stage, Fsd and Fsf architectures prevail, together with fluvial bars with thin aeolian intercalations into the channels (CHe and CHa). The wet systems consist of flooded interdunes, muddy plains, and different types of aeolian mesoforms in the channel (Fmp, Ffd and CHem). The analysis of present-day depositional subenvironments in the Guandacol valley and the definition of architectural elements serve as a potential analogue for studying ancient fluvial-aeolian interaction environments.

The influence of water level changes on sand bodies at river-dominated delta fronts：The Gubei Sag, Bohai Bay Basin

Changes in water level are one of the important factors controlling the constructive characteristics of deltas. The paper studies the influence of water level changes on sand bodies in the third member of the Shahejie Formation (Es3) on the gentle southern slope of the Gubei Sag, Bohai Bay Basin and draw some conclusions that, for complex sand bodies, with the increase in water level the distributary channels bifurcate frequently, from a simple branching shape to a network shape along with the increase in the development of crevasse splays, mouth bars and sheet sands. For single sand bodies, with an increase in water level in the slope zone of the lake basin close to the source area, the superimposition style transitioned from vertical cutting-stacking and lateral isolation to vertical stitching, isolation and lateral stitching. However, in the central zone of the lake basin far from the source area, the superimposition style transitioned from vertical stitching and lateral stitching to vertical isolation and lateral isolation. When water level stays stable, the greater the distance from the source area the greater the disaggregation ratio of a single sand body. At the same distance from the source area, higher water level tends to result in greater disaggregation ratio of a single sand body.

Groundwater vulnerability assessment of shallow aquifer in the South Texas sand sheet using a GIS-based DRASTIC model

Groundwater vulnerability assessment of shallow aquifer in the South Texas sand sheet using a GIS-based DRASTIC model

Study on oil and gas filling and migration and accumulation in synclinal reservoir area

In recent years, the focus of oil and gas exploration in western Daqing has changed from a single large structural high point packaged reservoir to a diversified complex structural low point syncline reservoir. Such reservoirs are mainly lithologic traps, with complex rules of oil and gas filling, migration and accumulation, and irregular oil-water distribution, resulting in unclear understanding of the formation and distribution of syncline lithologic traps. The typical GLN area dominated by lithologic reservoirs is selected as the research object. The oil and gas filling research under the condition of reservoir forming power is carried out by using the source reservoir pressure difference. Based on the plane distribution of crude oil density, the secondary migration and accumulation rule of oil and gas is studied. It is considered that GLN can contain oil in a large area, but oil and gas can not migrate in a long distance. The low value area of crude oil density is the breakthrough of primary migration and the starting point of secondary migration, and its formation is controlled by the principle of phase potential coupling. The sand body is highly heterogeneous and the oil-water distribution is complex, while the sheet sand is mainly pure oil layer, and the water layer is formed only in the parts far away from the breakthrough and poor physical properties.

Discussion of seismic diagenetic facies of deep reservoir in the East China Sea Basin

Evaluation of seismic diagenetic facies is an effective interpretation procedure to characterize the spatial distribution of diagenetic facies in deep tight sandstones in offshore sparse well areas. Based on petrographic and seismic data, research on seismic diagenetic facies was used in the proposed workflow to predict the spatial distribution and distribution characteristics of seismic diagenetic facies for the third (H4c) sub-member of the fourth (H4) member of the E3h Formation in the Xihu Sag, East China Sea Basin, Eastern China. Herein, two discriminant functions between the core-derived diagenetic facies and the seismic elastic parameters of shear modulus, p-wave impedance, and porosity data volume were established using the supervised learning method, and seismic data X and seismic data Y containing diagenetic facies information were evaluated. Based on the linear function between seismic data X and seismic data Y, a new seismic data volume was calculated and a comprehensive index of diagenetic facies was proposed to describe the distribution of diagenetic facies. The comprehensive index of diagenetic facies can better identify the spatial distribution of diagenetic facies. The results of seismic diagenetic facies research mainly focused on (1) the spatial distribution of diagenetic facies and (2) the distribution characteristics of diagenetic facies. Based on core-derived diagenetic facies, typical stratal slices, and sedimentary microfacies, the spatial distribution of seismic diagenetic facies in the two sublayers of the H4c sandstone was accurately interpreted. The northern part of the H4c1 and H4c2 sublayers mainly developed quartz-cemented facies and a small amount of chlorite-coated quartz facies. The southern part and the surrounding areas of the H4c1 and H4c2 sublayers primarily developed tightly compacted facies. The area near four (F1, F2, F3, and F4) faults in the H4c1 sublayer mainly developed a small amount of dissolution facies, whereas the area near the F2 and F4 faults in the H4c2 sublayer primarily developed a small amount of dissolution facies. Furthermore, the distribution characteristics of seismic diagenetic facies were investigated from the perspective of sedimentary microfacies and diagenetic facies. The chlorite-coated facies is mainly distributed in the subaqueous distributary channel sedimentary microfacies. The dissolution facies is primarily distributed in the subaqueous distributary channel and sheet sand sedimentary microfacies near the faults. This study shows that the research of seismic diagenetic facies using petrographic data and seismic data can better predict the spatial distribution of diagenetic facies of deep tight sandstone.

Anatomy and dynamics of a mixed contourite sand sheet, Ryukyu Island Arc, northwestern Pacific Ocean

Contourites are well-known from many continental margins under the influence of bottom currents but have been little reported from the Pacific Ocean. This paper documents a new area of contourite-controlled sedimentation in the NW Pacific Ocean, which we call the Ryukyu Sand Sheet. This contourite sand sheet has an area of around 35,000 km2 and extends from the narrow island shelves to over 1500 m water depth. It comprises mainly moderate to well-sorted fine-grained sands, with current ripples and giant sediment waves and is also associated with small drifts. It is formed under the influence of three principal current systems – the Kuroshio Current, the Kuroshio Countercurrent and the Ryukyu Current. The interaction of these currents with each other and with a complex seafloor topography, spawns a series of meso-scale gyres, eddies and vortices that shape the seafloor and lead to deposition of an extensive sandy substrate, locally with gravels and exposed seafloor. Strong surface currents, as well as deep-water thermohaline circulation, both influence the depositional and erosional processes of deep-sea sediments. The role of the modern Kuroshio Current in this context supports earlier work that proposed an ancestral Kuroshio Current for the deposition of Miocene contourites onshore Japan. Sediment supply to the Ryukyu Sand Sheet is by a mixed process of seafloor polishing and sand spillover that involves combined oceanographic and gravitational processes.

Coastal erosion and sediment reworking caused by hurricane Irma – implications for storm impact on low‐lying tropical islands

AbstractHurricane Irma (September 2017) was one of the most devastating hurricanes in recent times. In January 2018, a post‐hurricane field survey was conducted on Anegada (British Virgin Islands) to report on the erosional and depositional evidence caused by Hurricane Irma's storm surge and waves. We document the type and extent of hurricane‐induced geomorphological changes, allowing for an improved risk assessment of hurricane‐related inundation on low‐lying islands and carbonate platforms.Anegada's north shore was most impacted by Hurricane Irma. The surge reached about 3.8 m above sea level and onshore flow depths ranged between 1.2 to 1.6 m. Storm wave action created 1 to 1.5 m high erosional scarps along the beaches, and the coastline locally retreated by 6 to 8 m.Onshore sand sheets reached up to 40 m inland, overlie a sharp erosive contact and have thicknesses of 7 to 35 cm along the north shore. In contrast, lobate overwash fans in the south are 2 to 10 cm thick and reach 10 to 30 m inland.Moreover, the hurricane reworked a pre‐existing coast‐parallel coral rubble ridge on the central north shore. The crest of the coral rubble ridge shifted up to 10 m inland due to the landward transport of cobbles and boulders (maximum size 0.5 m3) that were part of the pre‐hurricane ridge.A re‐survey, 18 months after the event, assessed the degree of the natural coastal recovery. The sand along the northern shoreline of Anegada that was eroded during the hurricane and stored in the shallow water, acted as a nearshore source for beach reconstruction which set in only days after the event. Beach recovery peaked in February 2018, when beaches accreted within hours during a nor'easter‐like storm that transported large volumes of nearshore sand back onto the beach.

Contemporary and future dust sources and emission fluxes from gypsum- and quartz-dominated eolian systems, New Mexico and Texas, USA

AbstractRecent research on dust emissions from eolian dunes seeks to improve regional and global emissions estimates and knowledge of dust sources, particularly with a changing climate. Dust emissions from dune fields can be more accurately estimated when considering the whole eolian system composed of active to stabilized dunes, interdunes, sand sheets, and playas. Each landform can emit different concentrations of dust depending on the supply of silt and clay, soil surface characteristics, and the degree to which the landforms are dynamic and interact. We used the Portable In Situ Wind Erosion Laboratory (PI-SWERL) to measure PM10 (particulate matter <10 μm) dust emission potential from landforms in two end-member eolian systems: the White Sands dune field in New Mexico (USA), composed of gypsum, and the Monahans dune field in west Texas, composed of quartz. White Sands is a hotspot of dust emissions where dunes and the adjacent playa yield high dust fluxes up to 8.3 mg/m2/s. In contrast, the active Monahans dunes contain 100% sand and produce low dust fluxes up to 0.5 mg/m2/s, whereas adjacent stabilized sand sheets and dunes that contain silt and clay could produce up to 17.7 mg/m2/s if reactivated by climate change or anthropogenic disturbance. These findings have implications for present and future dust emission potential of eolian systems from the Great Plains to the southwestern United States, with unrealized emissions of >300 t/km2/yr.

Geological evidence of an unreported historical Chilean tsunami reveals more frequent inundation

Assessing tsunami hazards commonly relies on historical accounts of past inundations, but such chronicles may be biased by temporal gaps due to historical circumstances. As a possible example, the lack of reports of tsunami inundation from the 1737 south-central Chile earthquake has been attributed to either civil unrest or a small tsunami due to deep fault slip below land. Here we conduct sedimentological and diatom analyses of tidal marsh sediments within the 1737 rupture area and find evidence for a locally-sourced tsunami consistent in age with this event. The evidence is a laterally-extensive sand sheet coincident with abrupt, decimetric subsidence. Coupled dislocation-tsunami models place the causative fault slip mostly offshore rather than below land. Whether associated or not with the 1737 earthquake, our findings reduce the average recurrence interval of tsunami inundation derived from historical records alone, highlighting the importance of combining geological and historical records in tsunami hazard assessment.

Interdecadal climate variability identified in aeolian deposits in southern Santa Catarina, Brazil

Changes have occurred to the patterns of surface morphology in coastal aeolian deposits in a chrono-correlated way in different geographical areas at different time scales. These changes can be recognized and associated with meso and large-scale climatic events, thus establishing a teleconnection. In the present study, surface and subsurface data, combined with Optically Stimulated Luminescence (OSL) dating, allowed us to establish the evolutionary chronology and the environmental context of aeolian features that cover a stretch of the Holocene coastal barrier in the southern coast of Santa Catarina, Brazil. According to geophysical and geochronological data and geomorphological indicators, the section shows regressive coastal line behavior (progradational pattern). The sedimentary cover of this Holocene coastal barrier, so far dominated by active dunes, began to change after the 1930s. The subsequent decades were marked by a significant increase in vegetation, fixing the precipitation crests of the transgressive sand sheets (TSS). This increase in vegetation cover over the last century results from climatic variability associated with the Pacific Decadal Oscillation.

Alluvial fan development during the Holocene in the Qu'Appelle Valley, Saskatchewan

Alluvial fan sediments contain valuable information on environmental change and anthropogenic influences, and function as an archive of landscape development. The purpose of this paper is to describe the analysis of the sedimentary information from core samples taken from two alluvial fans in the Saskatchewan prairies. The analysis assessed grain size, organic matter content, and microfossil presence to identify periods of accumulation and stabilization. Parker, Beavers, and Product weathering indices were used to analyze the modern source soil samples and the borehole cores to determine weathering/leaching conditions. The bed‐load transport sediments showed a higher leaching intensity whereas lower leaching was revealed for periods of stability, silt sheet flows, and sand sheet flows. The Beavers Index was not only a strong indicator of a bed‐load transport layer, but also of calcium accumulation zones marking alluvial fan surface stability. The large Dolomite/Calcite ratio marking the calcium accumulation zones was used for correlation between the two alluvial fan sites on a regional scale. A comparison of the stratigraphy of the two alluvial fans documents that a relationship exists between agriculture and an increase in erosion.

A study of the Distribution of Sand Sheet on Some Pastures in the Western Desert of Iraq

This research aims to track the spatial extensions of the sand accumulations significantly over the past few years, on the pastoral lands of two regions in the Western Desert of Iraq for the years (2000-2005-2013-2019), depending on the techniques of remote sensing and geographic information system, which covered an area of (1826.5 km2), the satellite visuals of the Landsat sensors (OLI, TM) were used for the selected years of observations, within path 171, row 36 and 37, and the program to build classification equations within the ArcGis9.3 software environment for classification and mapping from the US Geological Survey website analysis, treatment, classification, improvement and calculation of the spread areas of sand accumulation, the results showed the affected areas in the north of Al-Rutba reached 304,443,268,280 km2, either in part of Wadi Al-Ratqah reached 289,346,191,113 Square kilometers, 34 grazing plant species belong to 12 families, The vegetative density ranged between 3.7 – 36.0 plant. m-2, the vegetation coverage was between 9.5-73.8 cm.m-2 and the total biomass was 28.1 g. m-2, noting the low values in the sand accumulations. This study emphasizes the need to develop policies, procedures and future plans to reduce the phenomenon of sand accumulation on pasturelands in the study areas.

Tectonic, hydrogeologic, and climatic controls on Late Holocene dune formation, China Lake basin, Indian Wells Valley, California, USA

AbstractAnalysis of patterns of faulting and hydrogeology, stratigraphic and sedimentologic studies, and luminescence dating of aeolian deposits in China Lake basin provide new perspectives on the origins and development of Late Holocene dunes and sand ramps in the seismically active Indian Wells Valley of eastern California. Aeolian dune and sand sheet deposits were sourced from alluvial material derived from granitic rocks of the south-eastern Sierra Nevada and are concentrated in areas with sand-stabilizing phreatophyte vegetation influenced by high groundwater levels along the active oblique-normal Little Lake and Paxton Ranch faults, which locally form barriers to groundwater flow. Three episodes of sand accumulation are recognized (2.1 ± 0.1 to 2.0 ± 0.1 ka, 1.8 ± 0.2 to 1.6 ± 0.2 ka, and 1.2 ± 0.1 to 0.9 ± 0.1 ka) during conditions in which sediment supplied to the basin during periods of enhanced rainfall and runoff was subsequently reworked by wind into dunes and sand ramps at the transition to more arid periods. Understanding the role tectonics plays in influencing the hydrogeology of seismically active lake basins provides insights to accurately interpret landscape evolution and any inferences made on past hydroclimate variability in a region.

High-resolution sequence stratigraphy and evolution of the Jeju Strait shelf, Korea, since the Last Glacial Maximum

Sequence analysis of high-resolution seismic profiles and sediment data from the Jeju Strait reveals that the shelf deposits form a depositional sequence consisting of a set of lowstand, transgressive, and highstand systems tracts deposited since the LGM. Six seismic units, each with different seismic facies and geometry, constitute three systems tracts. During the LGM, most of the continental shelf was exposed, resulting in sub-aerial erosion associated with paleo-channel incision, forming incised-channel fill (unit 1). The paleo-river may have supplied abundant terrigenous sediments to the study area around the paleo-river mouth. As the shelf flooded, these sediments were trapped within the paleo-estuary and formed estuarine deposits (unit 2). As transgression continued, the near-surface sediments were reworked and redistributed by shelf erosion, resulting in a thin transgressive sand sheet (unit 3) covering a large area of the shelf. Based on age dates and sea-level curves, a transgressive sand ridge (unit 4) formed during the stillstand or very slow rise period (13.7–11.5 ka BP). The Heuksan mud belt (HMB; unit 5), which is one of the prominent mud deposits located in the western part of the study area, can be divided into two subunits (5a and 5b). The lower part of the HMB (unit 5a) corresponds to shelf mud deposited during transgression. In contrast, the upper part of HMB (unit 5b) consists of recent shelf mud that was deposited during the highstand (after ∼7 cal kyr BP). The Seomjin subaqueous delta (unit 6), which consists exclusively of homogenous mud, was deposited after the sea-level highstand. Unit 6 indicates a transition from proximal to distal facies around the Seomjin River mouth. A single depositional sequence on the Jeju Strait shelf was mainly controlled by the complex interplay between bottom morphology, a varying sediment supply, and high-amplitude (∼130 m) sea-level changes, along with hydrodynamic conditions.

Ripples, Transverse Aeolian Ridges, and Dark‐Toned Sand Dunes on Mars: A Case Study in Terra Sabaea

AbstractRipples, transverse aeolian ridges (TARs), and dark‐toned sand sheets and dunes are common aeolian bedforms on the Martian surface. They are important for understanding the nature of present‐day Martian sediments and regional aeolian processes. Here we present a case study investigation of ripples, TARs, a dark‐toned sand sheet, and dunes in an unnamed—but well‐covered by remote sensing datasets—crater in Terra Sabaea, Mars, to consider their nature and possible origin scenarios. Repeat high‐spatial resolution images show only minor albedo changes among the dark‐toned sand dunes but no obvious changes in the ripples and TARs. Visible and infrared spectra show that the megaripples and TARs are pyroxene‐bearing, while the dark‐toned sheet and dunes are olivine‐bearing. Thousands of TARs are superimposed on the crater walls, and they have a similar composition as the bedrock exposed around the central pit, suggesting that some percentage of the sediment composing the TARs may be locally derived. Megaripples have a similar composition as TARs, suggesting they may share a similar origin. Dark‐toned sand sheets and sand dunes show a different composition from the substrate of the crater, plus bedform orientations indicative of a dominant, north‐northwest wind, indicating that some of these dark sands might have been blown in from outside of the crater. Alternatively, the sand in the megaripples, TARs, sand sheets, and dunes could share a common source, and some or even all of them could be recycled from the weathering and erosion of the sand‐bearing clastic rocks exposed in the crater walls.

Research on Sedimentary Microfacies of an Oil Layer in a Block of Songliao Basin

This topic uses debris, core log, core description data, combines regional research results, determine that the oil layer in a block of the Songliao Basin is the most developed in the front subfacies and prodelta subfacies of delta underwater sediment. Microfacies include underwater distributary channels, underwater natural levees, distributary bays, estuary dams, distal bars, sheet sand, and prodelta mud. The contiguous distribution of dam sand is the main feature of this area. On the basis of single-well facies research, it is the first time that this topic has studied the features of the plane and profile distribution of the reservoir sedimentary facies belt in the study area, and finally builds the sedimentary facies model, and provides a solid geological basis for fine reservoir description and favorable area prediction.

Wind regime and aeolian sand transport in Khuzestan Sand Sea

The Khuzestan Sand Sea extends from the Wasit and Maysan provinces in Iraq (22%) to the Ilam (10%) and Khuzestan (68%) provinces in Iran. In order to determine wind regimes and sand transport characteristics, hourly wind data records from 21 meteorological stations for the period 2000–2016 were analyzed using aeolian-sediment transport methods. The analysis of the wind energy based on drift potential (DP) revealed rather large spatial variations in the Khuzestan Sand Sea. The Iraqi part of the desert, as well as the southern regions of the Ilam province and the western edge of the Khuzestan province were characterized by particularly high wind energy (DP greater than 400), while towards the central area of the Khuzestan Sand Sea near Ahvaz city a sharp decrease to DP less than 200 was detected. In the southern and southeastern parts of the Khuzestan Province, the wind energy increased again and the DP reached more than 200 vector units. The temporal analysis of the DP showed no considerable temporal trends between 2000 and 2014 in this study area. The dune morphology analysis revealed a bimodal wind regime, which was also supported by the dominance of sand sheets and transverse dunes. Additionally, the local topography has an important influence on the formation of topographic dunes in the southeastern parts of the Sand Sea.

Morphological Response of Coastal Sand Sheets to Typhoons

Morphological Response of Coastal Sand Sheets to Typhoons

Facies analysis of the Quaternary fluvial system of Khor Eit, Red Sea coast, Sudan

This research article is a field-oriented facies analysis of Quaternary fluvial sediments of the ephemeral braided stream Khor Eit, located on the Sudanese Red Sea coast north of Port Sudan town. Although these sediments represent the main groundwater aquifers of the Red Sea coast of the Sudan, they have attracted less geoscientific attention. The present study is intended to fill part of this gap. Eleven fluvial facies were identified: three gravel facies, six sand facies and two mud facies. Based on the downstream geomorphic variation and systematic changes in the facies distribution, the study divides the Khor Eit into a proximal, middle and distal part. The high-energy flow regime in the proximal part is reflected in a characteristic fluvial facies association of channelized, sheet-like and erosive channelized gravel bodies and horizontally stratified gravels of the gravel bars. In the middle part, where the general slope becomes gentler, the facies display distinct fining-upwards dominated by scour-fill facies associations and elongated sheet-like interlayered sand dominated bodies. The fluvial sedimentation in the distal part is characterized by sheet-flood, and low-water accretionary deposits of thin interlayered sand and mud, and the mud drape facies associations. The analysis of the sedimentary architectural elements of the Khor Eit identified six major architectural elements: Gravel bars and bedforms (GB), Channels (CH), Sediment gravity flows (SG), Sandy bedforms (SB), Laminated sand sheets (LS) and Overbank fines (FF). Factors controlling sedimentation processes in the study area (rainfall, morphological aspects and vegetation cover) have been discussed. Identification and detailed documentation of the different fluvial facies types, facies associations the and the study of their lateral and vertical changes downstream allow the construction of a fluvial facies model for khor Eit.