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This research delves into the crucial role of groundwater in underpinning ecosystems and human resilience amidst drastic and unpredictable climate change, particularly as water resources face increasing sustainability concerns due to population surges and climate change. Utilizing a combined approach of SWAT-MODFLOW models, we estimate the streamflow discharge and groundwater recharge in the Choushui River Alluvial Fan, Taiwan. These models allow evaluation of the distribution and proportion of recharge areas as well as the accuracy and the potential influence of future climate change scenarios on groundwater recharge. The findings show a strong correlation between the simulation and actual observations, evidenced by the Nash–Sutcliffe model efficiency coefficients (NSE) of 0.920 and 0.846 for calibration and validation in the Choushui River, and 0.549 and 0.548 for the Pei-Kang River, respectively. The model demonstrates a reliable representation of the watershed response, supported by robust statistical performance. The analysis reveals the variable impacts of climate change on groundwater recharge, dependent on the chosen scenario and period. Some scenarios indicate that the maximum observed increase in groundwater recharge is 66.36% under the RCP2.6 scenario in the long-term period (2061–2080), while the minimum observed increase is 29.67% under the RCP4.5 scenario in the initial time frame; however, all demonstrate a decrease ranging from 23.05% to 41.92% across different RCPs in the impact of climate change over time, suggesting a potential long-term decrease in the impact of climate change on groundwater recharge. This study provides indispensable insights into the spatial hotspots in the top fan and the potential range of impact rates of climate change on groundwater recharge, underscoring the importance of continuous research and the thorough evaluation of multiple scenarios. Moreover, we establish a primary framework for using a top-ranked MIROC5 projection of general circulation models (GCMs) to delineate an essential premise that facilitates the advanced exploration of alternative scenario augmentations, bolstering the comprehensive investigation of climate change impacts on groundwater recharge. It is proposed that these findings serve as a guidepost for sustainable water resource management and policy-making in the face of climate change and escalating water demand. [ABSTRACT FROM AUTHOR]

This article presents the findings of a field experiment conducted in West Bengal to study the growth, yield, and water use efficiency of grass pea under different nutrient management practices. The results showed that fertilizing the grass pea plot with the recommended dose of fertilizer along with foliar application of Borax resulted in the highest plant height, number of branches, dry matter accumulation, number of pods per plant, pod length, number of seeds per pod, and 100-seed weight. The plot treated with RDF+ Borax also recorded the highest seed yield, stover yield, and water use efficiency. The study concludes that the combined use of RDF with Borax is the best option for better production of grass pea in terms of quality and quantity in the New Alluvial Zone of West Bengal. [Extracted from the article]

This article investigates the morphostructural evolution of the Labe and Jizera rivers confluence area in the Bohemian Massif of Czechia. The main stages of morphostructural evolution are identified and related landform patterns are described. The lithological and tectonic character of this contact area between the Barrandian and the Bohemian Cretaceous Basin has been gradually evolving since the Early Palaeozoic. Tectonic subsidence of the northeastern part of the Bohemian Massif and the Cretaceous transgression of the sea caused extensive marine sedimentation, which covered the pre-Cenomanian relief. The uplift of the Bohemian Massif during the Santonian initiated a widespread erosion and denudation in the Tertiary. The Labe River valley constitutes a remarkable boundary between the morphostructural plateaus in the south and the system of river accumulation terraces of the Labe and Jizera in the north. The originally extensive and currently considerably eroded III. river terrace of the Labe was formed in the Elsterian glacial period (Cromerian complex c). The conspicuous Jizera alluvial fan developed during the aggradation phase of the VII. river terrace in the Upper Pleistocene. Subsidence along the NW-SE-trending Labe Fault zone, deciphered from the vertical throw of the VII. terrace rock bases of Labe as well as related paleochannels of its local tributaries, which caused the current asymmetry of the Labe valley, reached up to 14 meters prior to the Holocene. The different rock resistance to weathering, arrangement of fault structures and neotectonic movements that took place even during the late Quaternary significantly influenced the intensity of varied climate-morphogenetic processes. [ABSTRACT FROM AUTHOR]

In southern Africa, the Okavango Delta is a large alluvial fan sustaining a unique wetlands ecosystem in the heart of the Kalahari desert. The Delta is fed by an annual flood that brings water from the Angolan plateaus to the north, down to the Okavango region. The fan is characterized by vegetated, permanent or seasonal floodplains, dotted with thousands of sandy islands of various origin (inverted paleo‐channels, paleo‐dunes, meander bars, etc). On at least some of these islands, shallow groundwater is characterized by a high pH (>8) and a high concentration of metals and metalloids, making it naturally toxic. In the 1990s, McCarthy and co‐workers explain the chemistry of that water through an evapotranspiration model, the flood‐water being pumped by the vegetation toward the center of the islands and progressively enriched in elements by evapotranspiration. This model has been widely applied to all islands in the Okavango, not considering their individual specificities nor that of the surrounding floodplain. Our work, based on a multidisciplinary approach including sedimentology, mineralogy and geochemistry, and discussed by McCarthy and Humphries, questions the established model suggesting that the alkaline water cannot derive from simple concentration of the floodwater. Key Points: The chemical composition of the alkaline groundwater cannot reflect simple evaporation processesThe variable origin of islands in the Okavango Delta makes for variable bio‐geochemical processesThe hydro‐geochemical functioning of the Delta will only be understood through interdisciplinary studies [ABSTRACT FROM AUTHOR]

Purpose: Although the formation mechanism of the megadunes in the Badain Jaran Sand Sea has received considerable research attention, their provenance and sand accumulation processes are still poorly understood. Therefore, this study aims to identify the provenance of the megadunes and clarify the spatial and temporal characteristics of their source supply processes. Materials and methods: We collected megadune sands in the Badain Jaran Sand Sea and sediments from their potential source regions (i.e., the Heihe-Altay alluvial fan, Heihe River, Beida-Yabrai alluvial fans, and Gulunai-Guaizi dry lakes). We analyzed the geochemical compositions of these sediments using X-ray fluorescence spectrometer. Source identification was conducted using robust K/Ba and K/Rb ratios and the multidimensional scaling (MDS) method. Based on fluvial-aeolian system distribution and comparison with drilling cores, the spatial and temporal source supply processes of the megadunes were determined. Results and discussion: The K/Ba vs. K/Rb biplot showed that the Heihe-Altay alluvial sediment, Heihe River fluvial sand, and the Beida-Yabrai alluvial sediment samples were similar to the sand in the megadunes. Similarly, MDS result showed that these sources had similarities to the megadune sand, indicating that they were the sources of the megadune sand. Based on the distribution of fluvial-aeolian systems, we conclude that the sediments from the Qilian Mountains and Altay Mountains were first mixed in the Heihe River, after which they were sorted and transported by the northwest wind to the megadune field. The Beida-Yabrai Mountains delivered source sediments to the sand sea via short-lived runoff episodes and southeast winds, which were not as significant as those previously described. These sands finally built megadunes in two directions, namely from the northwest to the southeast and its opposite direction due to the prevailing northwest wind and local air circulation from the slipface. By comparing drilling cores from within and near the sand sea, we found that fluvial sediments were prevailing in the lower reaches of the Heihe River during Marine Isotopic Stage (MIS) 4 and MIS 2, when the megadunes rapidly migrated. However, the Heihe-Altay alluvial fan formed since the Late Pleistocene when the sand sea began to form, indicating a more extended source supply history. Conclusions: Our results indicated that the Heihe-Altay alluvial sediments, the Heihe River fluvial sand, and the Beida-Yabrai alluvial sediments were the sources of the megadune sand. The sediments transported to the dune field by fluvial-aeolian systems at the sand sea scale and accumulated on the megadunes from both windward and leeward directions at the individual dune scale. Temporally, the Heihe-Altay alluvial fan may be a continuous source of sediments for the development of the megadunes, and the Heihe River may have contributed to their rapid migration during MIS 4 and MIS 2. [ABSTRACT FROM AUTHOR]

This work reports on data on a moderate effusive-explosive eruption of a summit crater of Alaid volcano (Atlasova Island, Northern Kuril Islands) observed from September 10 to December 1, 2022. Based on satellite and visual data, it was determined that the strombolian-vulcanian activity resulted in two lava flows, 2.6- and 1-km long, that outflowed onto the southern slope of the volcano and at least 16 emissions occurred to heights of 2.5 to 6 km a.s.l. The ash plumes spread out mainly in the southeast and east-southeast directions with their maximum length reaching 300–530 km. The eruption posed a danger to local airlines. The lava outflow provoked the formation of lahars that descended along the southern slope of the volcano and reached the island coast. The alluvial fan formed from mudflow masses partially deposited beyond the coastline, causing accretion of the island land. [ABSTRACT FROM AUTHOR]

For the first time, this study presents interpretations of alluvial fans in spectral decomposition RGB Blends, analysed in seismic time slices from the Middle Triassic to Lower Jurassic stratigraphical interval of the Horda Platform (northern North Sea). The time slices record a shifting alluvial fan front, fluvial variability, uplift and erosion and reveals depositional elements that may set the common conception of the geological development of this area during the Early–Middle Mesozoic up for discussion. Results show that the Upper Triassic Lunde Formation in the eastern margin of the Horda Platform was characterized by the deposition of coalesced alluvial fans. A variable extent of the fan front through the Upper Triassic is linked to interplaying allogenic factors: uplifted source areas in the aftermath of Early–Middle Triassic rifting determined sediment availability; climate transitioning from arid to semi‐humid, with increasingly fluctuating precipitation, controlled sedimentation, and run‐off; provenance dictated bulk sedimentology and affected prevailing alluvial processes. An overall retreat of the fan system through the Late Triassic coincided with a significant change in landscape characteristics at the transition into the overlying Statfjord Group. Uplift and initial tilting of the Horda Platform caused landscape degradation and the formation of plateaus and incised valleys, contemporaneous with increased humidity and marine transgression, forming estuaries. The shift in depositional style has implications for reservoir properties, creating complexity and heterogeneity in terms of facies distribution and connectivity, which may benefit potential CO2 storage. Upper Triassic alluvial fan development in the Horda Platform (northern North Sea) depicted through spectral decomposition of seismic time slices Enhanced level of seismic stratigraphic interpretation with RGB blending Impact of allogenic factors on alluvial depositional development Implications of alluvial variability on reservoir properties [ABSTRACT FROM AUTHOR]

In 1959, the plant community and abiotic environment of three 2.2-ha Chihuahuan Desert plots were studied in Big Bend National Park, Texas. In 2019 and 2020, we continued the study of these plots using the same methods with the goal of evaluating the long-term trends in the perennial plant communities of 3 different habitats within the park. Our study assessed species composition, density, and ground cover, which were compared with the same parameters reported from 1959. At a rocky site in the foothills of the Chisos Mountains, plant density decreased during the 61 years of the study (1959–2020) but remained high compared with the other sites. Many of the perennial plant species persisted, but the relative proportions of some species had changed over time. Another study plot was situated on a gently sloping alluvial fan at Panther Junction. Plant density and ground cover increased substantially on this desert pavement habitat. Much of the increased density can be attributed to grasses, particularly Lehmann lovegrass (Eragrostis lehmanniana), an exotic invasive species likely introduced as a result of human activity surrounding the nearby park headquarters at Panther Junction. A third plot was a level sandy habitat on Tornillo Flat. The density and species composition of the plant community at Tornillo Flat were remarkably stable between the 1959 and 2019 surveys. Factors likely affecting the plant community at the 3 plots include periodic drought, invasive species, fire, climate change, and secondary succession following past overgrazing of livestock that ended with the establishment of the national park in 1944. [ABSTRACT FROM AUTHOR]

The development of the Fennoscandian Ice Sheet (FIS) in its SW Baltic Sea sector during MIS 2 led to the formation of the Jasmund Glacitectonic Complex (JGC). The evolutional stages of the latter reflect small-dimensioned ice sheet oscillations. A glacitectonically formed piggyback basin is in focus to give direct information on the evolution of the JGC. We present a set of five OSL ages from syn-kinematic glacilacustrine and alluvial fan sediments deposited between ice margin-parallel thrust-bounded ridges from the southern margin of the JGC. The ice front proximal depositional environment and short transport distances of the sediments implicate a possible insufficient bleaching of the luminescence signal. Nonetheless, we were able to gain reliable ages of ~22 ka for the growth of the southern JGC. The samples pre-date the Oder ice stream reaching its maximum extent, the Pomeranian ice marginal belt at ~18-20 ka. A comparison of our data with the existing age data related to the evolution of the JGC will contribute to a better understanding of the FIS dynamics in the research area and the timing of the Pomeranian phase in NE Germany. [ABSTRACT FROM AUTHOR]

The metropolis of Tehran, the capital and the largest city of Iran, has been affected by the phenomenon of land subsidence in the past years. Up to now, no comprehensive study has been presented on land subsidence in the Tehran metropolis. This study addresses this shortcoming through a comprehensive investigation of surface and sub-surface factors that affect the subsidence and investigates the mechanism of subsidence development in Tehran. Land surface studies involve assessing the subsidence rate by utilizing InSAR technology, tracking the urban development of the city through time, and investigating geomorphological features like the alluvial fans landforms and surface drainage. Sub-surface studies include groundwater and geotechnical assessments. The evaluations indicate that the combinations of soils with a high percentage of fine grains and the drop in the underground water level are the major drivers of subsidence in the south of Tehran. The results of the study showed that the highest rate of land subsidence is 217 mm/year and has happened in the southwest of Tehran city. Districts 10, 11, 16, 17, 18, 19, and 20, which comprise about 26% of Tehran's population (about 2.3 million people in 2016), are affected by subsidence. According to the results obtained from the geomorphological studies, these areas are located at the end of the alluvial fan of Kan and Chitgar (south and southwest of Tehran). The paper also focuses on the sharp northward growth of the subsidence zone in the northeast corner of Tehran's subsidence zone. From investigations, it is concluded that changes in four river courses (which lead to a drop in the underground water level) in conjunction with fine grain soil of this area are (probably) the major factors that have played a role in the northward growth of the subsidence zone at the northeastern corner. The paper also identifies the most vulnerable urban districts affected by the subsidence as well as some major infrastructures exposed to subsidence hazards. [ABSTRACT FROM AUTHOR]

Debris flows in alpine environments are prone to occur in the context of global climate change (i.e., elevated air temperature and higher frequency of strong precipitation events). (Alluvial) Fans often develop at the outlet of tributaries after high‐intensity debris flows. Most debris‐flow fans in alpine canyon areas extend directly to the main river channel and become the forefront of the interaction between the tributary gully and the main river channel. Clarifying the development processes/dynamics, evolutionary mechanisms and driving factors of alluvial fans would shed light on understanding the geomorphological effects and genesis of river valleys in alpine canyon areas. Here, we report the development of debris‐flow fan at the outlet of the Tianmo Gully, a formerly hazard‐free but currently hazard‐active tributary of the Parlung Tsangpo Basin, Southeast Tibet, where debris flows have occurred frequently in the last two decades. Combining remote‐sensing images, DEM data, UAV aerial photography, RTK topographic survey and other fieldwork, the development processes and morphological characteristics of the Tianmo fan under the influence of four large debris flows were analysed. Both primary events (described as episodic debris‐flow events characterized by high‐magnitude mass movement) and secondary events (corresponding to perennial stream flow processes with much lower sediment concentrations) affected the development of the Tianmo fan. Episodic debris‐flow events drastically shape the macroscopic morphology of the fan, with rapid deposition and expansion of the fan body, whereas perennial stream flow processes slowly modulate the fan during the intermittent period between debris flows, mainly with gradual retrogressive incision and lateral migration of flow channel on the fan body. Influenced by the strong sediment‐transport process of debris flows and the alluvial fan development, the planform of the Parlung Tsangpo River evolved from a relatively narrow and single‐thread pattern to an alternating‐wide‐and‐narrow pattern, with a corresponding staircase‐like longitudinal profile. [ABSTRACT FROM AUTHOR]

Summary: Sedimentary units in alluvial fans may record gradual transport and deposition during multiple floods or sediment‐laden flows or, conversely, during few catastrophic events. While outcrops are a valuable source of direct information to constrain past geomorphic and hydrologic processes, such exposures are scarce, especially along aggrading rivers or those that have been subject to recent catastrophic sedimentation. In this context, near‐surface geophysical techniques can constrain the dimensions, internal architecture, composition, and petrophysical properties of different sedimentary units. We consider the Grimmbach alluvial fan in the cuesta landscape of southwestern Germany, which was heavily impacted by sediment and wood loads during a flash flood in 2016; published radiocarbon dates indicate that at least three floods similar to the one in 2016 may have occurred since the 17th century. To test whether and to which detail near‐surface geophysics might reveal the sedimentary legacy of these floods, we survey the Grimmbach alluvial fan using detailed topographic data and geophysical imaging based on electromagnetic induction, electrical resistivity tomography (ERT), and ground‐penetrating radar. Our geophysical results indicate former channel courses and two coarse bar deposits up to 3 m below the surface, which are comparable with the more extensive bar deposits of the 2016 flood. From the ERT models, we interpret coarse, up to 5 m thick, gravel lag overlying bedrock at a maximum depth of 10 m. Our geophysical results also highlight patches of finer materials derived from gradual sedimentation and soil development. Overall, our results show that the Grimmbach alluvial fan may have formed and reshaped during catastrophic flows, which likely caused channel avulsions. Our findings point to the need to reconsider flash flood and debris‐flow hazards in similar headwaters and fans of this seemingly quiescent cuesta landscape in southern Germany. [ABSTRACT FROM AUTHOR]

ABSTRACTThe aim of this paper is to present a detailed geomorphological map of the western piedmont of Cumbres Calchaquíes (Tucumán Province, NW Argentina) bounded by the Amaicha River to the south and the administrative border with Salta Province to the north. It contains information about geomorphological units, their relative ages, and morphogenetic processes. The main map shows the presence of seven aggradation stages separated by incision phases. The first three stages (St1, St2, and St3) were modeled on a thick accumulation located in the upper piedmont from the Late Pliocene and Early Pleistocene. Intermediate stages (St4 and St5) are alluvial fans and pediments with less thickness and gradient. They cover the Early Pleistocene (St4) and the Late Pleistocene-Middle Holocene (St5). Finally, stages St6 and St7 are from the Upper Holocene.

The Niger River (NR) is threatened with silting up due to the evolution of alluvial fans (AFs) in the Niamey region. The most significant is the Kourtéré AF. This study aims to map the spatial extent of this AF and analyze its progression and impact on the NR using a machine learning algorithm such as support vector machine on Landsat and Sentinel-2 images from between 1985 and 2021. Sentinel-1 data were then used to generate a digital terrain model at 10 m resolution through the Interferometric Synthetic Aperture RADAR (InSAR) technique to understand the Kourtéré watershed hydrology. Results show that the AF area increased from 55.19 ha in 1985 to 303.86 ha in 2003 and 237.18 ha in 2021. The AF has invaded a section of the NR since 2000 and began to invade its main bed in 2016. More than 73.71 ha of NR were converted into AF between 1985 and 2016. The flow direction of the NR has been disturbed by changes in AF, making it easier to overflow at flows much lower than previously. The Kourtéré watershed is dominated by a dense network of gullies with a Sediment-Transport Index of 424.4, which facilitates significant sediment transport into the AF and NR and leads to its silting up. [ABSTRACT FROM AUTHOR]

The Bovey Basin in south Devon, UK, provides an instructive example of a Palaeogene pull‐apart basin with a complex fluvial sedimentary fill. The basin, one of three that lie along the NW‐SE‐trending Sticklepath Fault Zone, is filled by about 1200 m of sediment, of which about the lower 700 m (mainly lower Bovey Formation) is concealed. The main Bovey Basin is separated from a smaller sub‐basin (the Decoy Basin) south of Newton Abbot. Two main lithofacies are present in the Bovey Formation: lignite‐clay; and clay‐sand, with subordinate lithofacies of red‐mottled clay and sand; and gravel and conglomerate. The upper 500 m or so of the sedimentary infill (middle and upper Bovey Formation) is divided into 10 members. Deposition in the basin was by a variety of fluvial processes, notably floodplain clays and sands deposited by meandering rivers; forest swamps with associated short‐lived shallow lakes; and (mainly in the upper Bovey Formation) braided stream sands and gravels that formed mainly on alluvial fans. Lignites in the basin formed from plants that grew in place in forest swamps, a revision of the long‐held view that the lignitic material was transported into the basin from forests of the conifer Sequoia couttsiae growing outside the basin on adjacent uplands. Newly discovered ichnofabrics occur in some lignitic sequences and probably represent root traces (rhizoliths). [ABSTRACT FROM AUTHOR]

The Pergamon micro-region (western Türkiye) has experienced several phases of increased geomorphodynamics during the Holocene. However, the role of local–regional human activities during a transformation between Hellenism and the Roman Imperial period and supra-regional climate fluctuations is still under discussion. Five sediment profiles from the alluvial fan of the rural Deliktaş catchment are analyzed and radiocarbon-dated to provide a sedimentological record covering the Holocene. Our results indicate seven phases of changing sediment dynamics. Five Holocene cycles of coarse- and fine-textured fan sediment deposition covered the paleochannel deposits of the Çaylak creek, and the floodplain sediments of the receiving Geyikli river which aggraded toward the piedmont during the Mid-Holocene. The landscape became stable on the Deliktaş fan and Geyikli floodplain at least ca. 4–3.4 cal ka BP as indicated by paleosols. These paleosols were again buried by fan sediments marking the first phase of accelerated geomorphodynamics during the Late Holocene. Both the local onset of human activities and the regional Mid-Holocene aridization with rapid climate changes play a role. The increased number of archeological sites and high human pressure on the environment during the Hellenistic–Roman transformation in the Deliktaş area and Pergamon micro-region were hypothesized to contribute to a phase of increased geomorphodynamic activity during the last 2.5 ka. This, however, is less apparent in our record. Our study emphasizes the importance of both, the climatic system and rural-urban cultural history, on landscape development, suggesting potential responses of locally diverse geomorphodynamics on regional-scale transformation in the eastern Mediterranean. [ABSTRACT FROM AUTHOR]

Zarrindasht County is a county in Fars Province in the south of Iran. This county is located between the folded parts of Zagros. In this area, there are many anticlines and synclines. The present study was performed to assess active tectonic using morphometric indices for the Zarrindasht area (South of Iran). In these studies, the topographic map of the Zarrindasht area, scale 1 : 50 000 and different satellite images were utilized to evaluate the morphometric features of the study area and to measure morphometric indices. Also, information related to lithology, faults, and other geological parameters was obtained from the geological map of the Zarrindasht area, scale 1 : 100 000. A total of 4 geomorphic indices such as the Mountain-front sinuosity index (Smf), drainage basin shape index (Bs), hypsometric integral index (Hi), and the ratio of valley-floor width to valley height (Vf) were studied in the selected locations. The results of these studies showed that most regions of the study area are moderate in terms of tectonic activity. So, in all of these basins, tectonic activity is more than erosion. The final result of the analysis of geomorphic indices showed that in the basins that have high and moderate tectonic movements, there are fault valleys, alluvial fans of the fault mountain front, fault escarpments, etc. Also, the formation of these shapes is affected by the active tectonics in the region. [ABSTRACT FROM AUTHOR]

Searching for life is one of the most important targets of Mars exploration missions. It has been considered that the Martian subsurface, away from the extreme surface environment, is a potentially habitable region for microbial growth. However, the distribution pattern of potential microbial habitats in the Martian subsurface has yet to be evaluated. Here, we investigate the subsurface habitats to depths of 20–60 cm from various landscapes, including slopes, gullies, channels, playas, and alluvial fans across the Mars-analog Qaidam Basin, NW China. We characterize subsurface niches by measuring microbial biomass and radiocarbon ages, and correlate them with soil properties including depth, moisture content, total organic carbon content, electric conductivity, pH, evaporite and clay mineral contents. We find more habitable niches for microbial colonization at depths of 5–25 cm as compared with the surface and deep subsurface across the hyperarid Qaidam Basin. Maximum biomass and biotic activity could be correlated with physical stability, limited radiation, and short-term moderate water availability in the shallow subsurface in hyperarid deserts. The findings of this study provide new perspectives on subsurface microbial habitats in Mars-analog hyperarid deserts and ongoing biosignature detection on Mars. [ABSTRACT FROM AUTHOR]

The application of integrated methods to evaluate the quality of reservoir rocks is becoming crucial in petroleum geoscience. The Miocene reservoirs in the El Morgan Oil Field consist mainly of sandstones with interbedded dolomitic silts and shales. Based on the pore scale, the sandstone reservoir of Hammam Faraun Member is a heterogeneous reservoir, and this is the main challenge in this oil field that affects both production and exploration activities. In this article, we have integrated the well logs, nuclear magnetic resonance (NMR), artificial neural networks (ANN) and core analysis to better understand these alluvial fan sandstone reservoirs. The petrographic description indicates arkosic sandstone with varied pore types, texture, cement, and sorting. The studied flow and storage capacity for well#1, indicate four rock types with 24 flow units and eleven barriers, which indicates a high degree of heterogeneity. The artificial neural networks (ANN), that is, the K.mod module, were used to enhance the prediction quality and forecast of FZI in the uncored intervals, where the NMR‐calculated permeability acts as a calibration point for the FZI model validation. This study reveals that the FZI is controlled by permeability, which is mostly influenced by pore throat size. The NMR log showed varied free fluid volume with varied capillaries, clay‐bound volumes and minor streaks of tar along the studied unit. The reservoir pores in the study area are residual pores that have undergone mechanical compaction and cementation that reduce porosities, while dissolution enhances the sandstone porosities. Porosity and permeability were significantly reduced in the presence of clays and carbonate minerals, which indicates poor reservoir quality zones in some parts. The primary factor influencing permeability is pore throat size, which is heavily influenced by the depositional environment and subsequent diagenetic processes. The findings of this study could lead to the development of accurate reservoir static models for future exploration and development plans in the studied area and elsewhere in similar depositional settings. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to analyze the spatial distribution characteristics of soil physicochemical properties and soil enzyme activities in different micro-topography and their differences, and to explore the interrelationship between them, which can provide a theoretical basis for the study of alluvial fan development mechanism, ecological restoration and agricultural production in the eastern part of the Helan Mountain. [Method] The physical and chemical properties of soil and soil enzyme activity were analyzed in different micro-topography ( alluvial terrace, high diffuse beach, slotted beach and gully bed) and soil depth ( 0 - 20, 20 - 40 cm) based on field survey sampling and laboratory analysis, and the relationship between soil enzyme activity and soil physical and chemical properties was investigated by using geographic probe combined with exemplary ranking method. The relationship between soil enzyme activity and soil physicochemical properties was investigated using a geodetector combined with the canonical ranking method. [ Result] In different micro-topography, the contents of soil gravel, organic matter, total nitrogen and alkaline nitrogen showed that alluvial terrace > alluvial terrace > trough terrace > furrow bed, and the contents of fast-acting phosphorus and fast-acting potassium showed that alluvial terrace > trough terrace > furrow bed, and the contents of each element decreased with the increase of soil thickness; The differences of soil pH, total phosphorus and total potassium were not significant in different micro-topography; Soil enzyme activities in different micro-topography showed that Alkaline phosphatase and urease activities were the highest in alluvial terraces and the lowest in gully beds, while catalase and peroxidase activities were the highest in gully beds and the lowest in alluvial terraces. The activities of alkaline phosphatase, urease and peroxidase decreased with the increase of soil thickness, and the activities of peroxidase increased with the increase of soil thickness. The results of geodetecting showed that the spatial variation of soil enzyme activities in different micro-topography in the study area was the result of the joint action of various soil physicochemical properties, and different factors had different degrees of influence on soil enzyme activities. Further redundancy analysis showed that total nitrogen, alkaline nitrogen, soil gravel content and fast-acting potassium were the main indicators influencing the variation of soil enzyme activity in the alluvial fan area of the eastern Helan Mountains, with the following order of importance: Total nitrogen > alkaline nitrogen > soil gravel content > fast-acting potassium. [Conclusion] The distribution of soil enzyme activity in the alluvial fan area of the eastern Helan Mountain varies significantly between different micro-topographic soils, and the effect of each soil physical and chemical property on soil enzyme activity varies, revealing the complexity of the relationship between soil physical and chemical properties and soil enzyme activity and the diversity of factors affecting the variation of enzyme activity spatial distribution. [ABSTRACT FROM AUTHOR]

We develop a robust and simple rule‐based algorithm to autonomously simulate alluvial fan deposition and evolution under continuously developing landscape conditions without prescribing deposition locations or imposing topographic constraints. Augmented with this algorithm, landscape evolution models are capable of dynamically detecting locations of potential fan deposition by statistical measures of surface topography and fluvial dynamics, then depositing fan sediments where and when the developed conditions require. To assess the method's efficacy in depositing sediment at a mountain‐valley transition zone characterized by a transport surface that permits unobstructed exit of sediment and water, a hypothetical scenario is created that involves a frontal, normal fault. It is followed by a series of sensitivity analyses to ascertain the influence of parameters affecting fan deposition and secondary processes. Uplift (u) and precipitation significantly impact fan morphological characteristics, which are within the range of real‐world fans. Higher rates of each cause the notable expansion of the fan area except in cases of exceptionally high precipitation rates. Fan area has a power‐law relationship with most of the tested parameters, Af∝u0.94μ0.31lf−0.14Kmax−0.65Acβ, where μ is erodibility (lithology), lf and Kmax are fluvial parameters, and Ac is catchment area (β~0.9). This study is the first showcasing fan power‐law relationships using numerical modelling. While fan area increases with precipitation, there exists a threshold beyond which fan area diminishes, and the formation of fans ceases altogether. The algorithm provides a basis for improving mechanistic understanding of fans by offering a robust platform for testing process dominance and scaling. The results demonstrate its applicability for landscape evolution simulation over a long time and broad spatial scales. We also investigate the hydrological significance of including autonomously generated alluvial fans in coupled landscape evolution—hydrology models that focus on groundwater as well as surface water hydrology. [ABSTRACT FROM AUTHOR]

On the Island of Samos (East Aegean region, Greece), two sedimentary basins are filled by thick continental series dated to the Late Miocene to Early Pliocene. A multidisciplinary study has been performed including (1) the definition of 21 sedimentary facies, (2) a review of the biological components and (3) carbon, oxygen and strontium stable isotope analyses. The succession is characterised by various depositional settings and hydrochemical compositions. Five main stages of basin evolution have been identified: (1) The Late Serravallian is marked by the development of alluvial fans and fan delta; (2) during the Lower Tortonian, isolated shallow lakes with variable salinity, from fresh to brackish, developed under warm and relatively humid conditions; (3) the Middle to Upper Tortonian is marked by the development of a large and deep lake with saline and alkaline waters, under colder and drier conditions; (4) the Latest Tortonian to Messinian period is represented by an ephemeral alluvial system, developed under a dry climate; (5) during the Zanclean, a palustrine and paludal wetland system, dominated by tufa carbonates, developed under moderately humid conditions. This succession is of particular interest for the reconstruction of the palaeoenvironmental evolution of the transition zone between the Mediterranean domain, and the Paratethys and circum‐Paratethys areas. The geochemical data and the presence of flora (diatoms) and fauna (gastropods) of marine affinity suggest transient ingressions of marine‐related water or groundwater inflows as early as the Lower Tortonian. The Samos succession records the complex interaction between the regional geodynamics and climate. The extensional regime of the Eastern Aegean zone generates subsidence, interrupted in the mid‐Tortonian (9 Ma) by a brief compressive event and a major exposure of the basins. Furthermore, the Late Miocene progressive aridification, followed by a change to a more humid climate (Pliocene) is also a major driver of the sedimentation. [ABSTRACT FROM AUTHOR]

Settlement crises in ancient cultures of Western Asia are commonly thought to be caused by climatic events such as severe droughts. However, the insufficient climate proxy situation in this region challenges the inference of clear relationships between climate and settlement dynamics. We investigate the Holocene climatic changes on the Varamin Plain in the context of the climatic history of Western Central Asia by using a transient comprehensive Earth System Model simulation (8 ka BP to pre-industrial), a high-resolution regional snapshot simulation and a synthesis of pollen-based climate reconstructions. In line with the reconstructions, the models reveal only slightly varying mean climatic conditions on the Varamin Plain but indicate substantial changes in seasonality during the Holocene. Increased precipitation during spring, combined with lower temperature and potentially stronger snow accumulation on the upstream Alborz mountains may have led to an increased water supply on the alluvial fan during the vegetation period and thus to more favourable conditions for agricultural production during the Mid-Holocene compared to modern times. According to the model, dry periods on the Central Iranian Plateau are related to particularly weak Westerly winds, fostering the subsidence in the mid-troposphere and hampering precipitation over the region. The model reveals that dry periods have spatially heterogenous manifestations, thus explaining why they do not appear in all proxy records in the wider study region. In fact, the climatic signal may depend on local environmental conditions. The interaction of the topography with the atmospheric circulation leads to additional spatial heterogeneity. Although our results provide several indications for a connection between climate and settlement dynamics, the small overall changes in moisture call into question whether climate is the main driver for settlement discontinuities on the Central Iranian Plateau. To shed further light on this issue, more high-resolution long-term proxy records are needed. [ABSTRACT FROM AUTHOR]

This study focuses on contemporary geomorphic changes in the proglacial valley floor of the Scott River catchment (northwest of Wedel Jarlsberg Land, southwestern Spitsbergen). The similarity and variability of landforms along the entire 3.3 km length of the unglaciated valley floor was assessed using precision terrestrial laser scanning (TLS) measurements made in July/August 2010–2013. Digital terrain models (DTMs) were generated from the high-resolution TLS survey data, followed by a geomorphon map, which was then used for a similarity and changes of morphology analysis performed with GeoPAT2 software. The study revealed a large spatial variation of contemporary processes shaping the valley floor and changes in its morphology. Their spatial distribution relates to the geologically determined split of the valley floor into three morphological zones separated by gorges. The upper gorge cuts the terminal moraine rampart, which limits the uppermost section of the valley floor, which is up to 700 m wide and is occupied by the outwash plain. The study showed that this is the area characterised by the greatest dynamics of contemporary geomorphic processes and relief changes. The similarity index value here is characterised by a large spatial variation that in some places reaches values close to 0. In the middle section stretching between the upper gorge (cutting the terminal moraine) and the lower gorge (cutting the elevated marine terraces), a much smaller variability of processes and landforms is observed, and the found changes of the valley floor relief mainly include the area of braided channel activity. Similarity index values in this zone do not fall below 0.65. The lowest section, the mouth of the alluvial fan, on the other hand, is characterised by considerable spatial differentiation. The southern part of the fan is stable, while the northern part is intensively re-shaped and has a similarity index that locally falls below 0.5. The most dynamic changes are found within the active channel system along the entire length of the unglaciated section of the Scott River. The peripheral areas, located in the outer zones of the valley floor, show great stability. [ABSTRACT FROM AUTHOR]

This study analyzed long-term fluctuations of groundwater levels in six shallow observation wells in the Nasunogahara alluvial fan, Japan's second largest source of agricultural irrigation groundwater, and presented a simple method for predicting groundwater levels in April prior to the annual planting of paddy rice. The 22-year time-series of groundwater levels (1998–2019) clearly showed seasonal periodicity, with higher levels in summer than in winter. In particular, groundwater levels were lowest in April when groundwater demand was greatest. Groundwater levels in two wells at the beginning of the April irrigation period showed long-term declining trends that can be attributed more to changes in land use than to changes in precipitation or air temperature. A simple linear regression of mean groundwater level in April to antecedent precipitation provided reasonable predictions of April groundwater levels, which were significantly influenced by precipitation in the preceding 3–5 months. Further modeling after subtraction of long-term seasonal trends (detrending) improved these estimates. The performance of the linear regression model for prediction of April groundwater levels is comparable to that of the statistical benchmark model. Using long-term monthly or seasonal weather forecasts, the modeling presented here can be applied to inform appropriate changes of water use practices, such as decreasing groundwater extraction by implementing rotational water supply, changing rice-cropping seasons, or targeting deeper aquifers. The identification of the critical period of antecedent precipitation that affected April groundwater levels in the Nasunogahara alluvial fan is also important for understanding appropriate precipitation periods to be targeted in modeling for future drought risk assessments under climate change. [ABSTRACT FROM AUTHOR]

Evidence points out that increasing plant productivity associated with greater erect shrub abundance alters soil organic carbon (SOC) stocks in the Arctic. However, the underlying plant economic traits remain poorly examined, which limits our understanding of plant–environment interactions driving tundra carbon cycling. We explored how erect shrub abundance leads to SOC variation in a High Arctic tundra (Bylot Island, Nunavut, Canada), where the only erect shrub, Salix richardsonii, has settled along currently active and abandoned channel zones of alluvial fans. The effects of vegetation and local environmental changes on SOC were evaluated through a paired sampling of soil materials and plant aboveground functional traits associated with plant carbon supply and nutrient demand processes. The occurrence of S. richardsonii, characterized by a tenfold increase in aboveground biomass, induced a 28% increase in SOC compared to adjacent plots dominated by prostrate shrubs and graminoids. Yet, this vegetation effect was solely observed along active channels, where higher SOC was associated with greater leaf and stem biomass. A path analysis showed that shrub leaf area index and total leaf nutrient content best represented plant carbon supply and nutrient demand dynamics, respectively, and jointly regulated SOC variation. This study underscores that vegetation structural changes associated with increasing erect shrub abundance in the Arctic can promote soil organic carbon storage, but that this pattern may be mediated by strong plant–environment interactions. Accounting for changes in functional traits driving plant carbon supply and nitrogen demand proves important for a better mechanistic understanding of how shrubification impacts tundra carbon cycling. [ABSTRACT FROM AUTHOR]

The regional geochemical mapping was carried out in the Indo-Gangetic alluvial plain of the Western and Central India which was previously classified as Varanasi alluvium, a polycyclic sequence of large alluvial fans transported by perennial Himalayan Rivers. The results based on the geochemical dispersion pattern of major and minor oxides as well as trace elements conclude that there are four major factors determining the dispersion patterns of the variables which are: (1) the underlying lithology with a strike of NE-SW, (2) transport of sediments along the general slope of the study area towards south and south-west as reflected in the Digital Elevation Model, (3) formation of Reh and (4) anthropogenic influence. The present study focusing on the effect of the underlying geology on the geochemical signature of the study area infers that the geochemical distribution pattern of certain variables clearly follows the trend of the Delhi fold belt. It can be interpreted that the subsurface lithology belonging to Delhi Supergroup is present at a depth of 500m which is considerably shallower, imprinting its geochemical signature on the sediments. The presence of minor outcrops of quartzite belonging to the Delhi Supergroup with the NE-SW strike is also documented in the study area. Based on this study we propose to reclassify the Varanasi Alluvium sediments as equivalent to Banda Alluvium. The study also demonstrates the utility of geochemical mapping as a tool to map the subsurface geology of an alluvial terrain. The results of this study are also corroborated by the regional scale gravity survey. [ABSTRACT FROM AUTHOR]

This study investigated the impact of active tectonics, specifically the Dorubeh fault and an oblique-slip reverse fault, on the morphology of alluvial fans situated between Kashmar City and Ali Abad Keshmar Village in Bardaskan. The research employed a cartographic-analytical approach, utilizing 1:25,000 topographical maps, 1:100,000 and 1:250,000 geological maps, Landsat satellite images, and Google Earth. Mapping and image processing were conducted using such software as ArcMap, ArcView, Google Earth, and QGIS. The results demonstrated that fault activity plays a crucial role in shaping the predominant geomorphic features within this region, specifically the formation of alluvial fans known as bajada. The oblique-slip reverse fault, specifically, has induced significant modifications in the alluvial fans. It has repositioned the primary channels from central to peripheral and lateral positions, leading to alterations in sediment deposition patterns. Consequently, certain alluvial fans now intersect at three transverse surfaces and two longitudinal and transverse surfaces. The Doruneh fault's activity is characterized by the manifestation of uplifts, pressure ridges, and pressure anticlines occurring at various sections within the alluvial fans, including the upper, lower, and basal regions. This fault caused left-lateral offsets in certain sub-channels on the fan's surface, resulting in the development of single-surface and nested two-surface transverse and longitudinal alluvial fans at the base of the fan and the base of the pressure ridges. Furthermore, it modified the point of intersection of the primary alluvial channels, leading to the formation of segmented fans downstream of Doruneh fault. [ABSTRACT FROM AUTHOR]

Striking examples of calcretes have been formed in alluvial and aeolian sediments of the Qazvin Plain in Iran. In the present research, eight profiles were studied, varying from recent proximal alluvial fans to adjacent alluvial plains and sand dunes. Macroscopic, microscopic, isotopic, and elemental composition studies show that both pedogenic and non-pedogenic processes have been responsible for the formation of these horizons. The remarkable features of the calcretes in this study are the prevalence of spores, nanofibers, and pisoids. This research provides clues for organisms involved, and the interface of soil with the atmosphere or the rhizosphere in the calcretization process. Nanofibers only occur around root traces in the pisoides and gypcretes. The shape of nanofibers reflects the contribution of roots and their associated microorganisms in the formation of calcrete and gypcrete. According to the results of the present study, the main factors controlling the calcretization are climate, calcrete position in the landscape, a host material, and topography. The stable isotope analysis of two alluvial fan profiles show that δ13C and δ18O values range for the groundwater calcretes in the phreatic zone from −4.34 to −1.98‰ and −9.26 to −6.97‰, respectively. These values suggest a high contribution of soil-derived light isotopes in meteoric water. These ranges in the vadose zone vary from −1.98 to −7.32 ‰ and −9.26 to −7.32‰, respectively. This result can be attributed to the density and types of vegetation, host detrital sediments, meteoric water, and evaporation that have controlled the isotopic composition of the calcretes. [ABSTRACT FROM AUTHOR]

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The timing and character of the initial marine flooding of extensional basins has implications for their tectonic history. Yet, the recognition of such flooding is difficult along rift basin margins due to the dominance of coarse‐grained systems and the lack of marine fauna. This study conducts detailed facies and stratigraphic analysis of a Mio‐Pliocene alluvial fan and fan‐delta succession in the Fish Creek Vallecito Basin in southern California. Our goal is to characterize the marine flooding surface, determine the paleogeographic position of the shoreline and estimate the magnitude of relative base‐level rise that occurred during the marine incursion associated with the opening of the Gulf of California. Our results show that the flooding of the Elephant Trees alluvial fans is often marked by an abrupt lithologic and facies change from meter‐scale boulder‐rich subaerial debrites (proximal alluvial fan facies association) to centimetre‐scale granule‐rich subaqueous debrites, ripple‐laminated sandstones and mudstones (prodelta facies association). By delineating the zone of transition between the subaerial and subaqueous facies, we place the initial flooding paleo‐shoreline 4 km up the alluvial fan's paleo‐depositional slope. Considering alluvial fan slope gradients between 1° and 5°, this 4 km transgression would require an estimated 70–350 m of water depth during the initial marine incursion. Interfingering of fan‐delta deposits with subaqueous marine and planktonic‐rich evaporites suggests that the basin was below sea‐level after, and perhaps even before, the marine flooding. Subaerial subsea‐level basins exist in Death Valley and the Salton Trough today within similar extensional and transtentional tectonic regimes. This subaerial subsea‐level interpretation might explain the high magnitude and abrupt relative base‐level rise recorded by the facies transitions in the Fish Creek Vallecito Basin. These results suggest that the Fish Creek Vallecito Basin underwent significant extension during its early and nonmarine depositional phase, allowing it to reach subsea‐level elevations. The tectonic history of the Fish Creek Vallecito Basin maybe similar to other extensional basins where rapid subsidence allows the accumulation of nonmarine strata below sea‐level prior to the marine flooding, then restricted and deep marine strata immediately after flooding. [ABSTRACT FROM AUTHOR]

Possible young analogues for regionally extensive unconformities (100 to 400 km2) in the gold-bearing Witwatersrand Supergroup (Archean, South Africa) occur in the South Island of New Zealand. Extensive marine unconformities in New Zealand show progression from an unconformity surface to conglomerate to clean well-sorted sandstone to marine mudstone, as is also found in the major Witwatersrand auriferous reef horizons. The hosting young sedimentary basins of the South Island rest on thin or thick crust on inboard and outboard foreland settings, with variable alluvial gold budgets. They expose the Cretaceous–Oligocene Waipounamu Erosion Surface unconformity that formed when most of New Zealand was subsiding, and Pleistocene–Holocene unconformities related to global sea level changes. The Witwatersrand gold-bearing reef sediments are a good match for such marine transgressions, but not alluvial fans or braided streams. Most Witwatersrand gold is immediately above planar unconformity surfaces and not restricted to, or concentrated in, erosion channels that are incised through the reefs. However, in modern alluvial fans or braided streams, gold is almost entirely in erosion channels on a smaller scale than the Witwatersrand gold reef packages and not spread across the planar unconformities. Alluvial fans and braid plains in New Zealand dilute gold with large volumes of gravel. [ABSTRACT FROM AUTHOR]

The research aims to classify alluvial fans' morphometric properties using the SOM algorithm. It also determines the relationship between morphometric characteristics and erosion rate and lithology using the GMDH algorithm. For this purpose, alluvial fans of 4 watersheds in Iran are extracted semi-automatically using GIS and digital elevation model (DEM) analysis. The relationships between 25 morphometric features of these watersheds, the amount of erosion, and formation material are investigated using the self-organizing map (SOM) method. Principal component analysis (PCA), Greedy, Best first, Genetic search, Random search as feature selection algorithms are used to select the most important parameters affecting erosion and formation material. The group method of data handling (GMDH) algorithm is employed to predict erosion and formation material based on morphometries. The results indicated that the semi-automatic method in GIS could detect alluvial fans. The SOM algorithm determined that the morphometric factors affecting the formation material were fan length, minimum height of fan, and minimum fan slope. The main factors affecting erosion were fan area (Af) and minimum fan height (Hmin-f). The feature selection algorithm identified (Hmin-f), maximum fan height (Hmax-f), minimum fan slope, and fan length (Lf) to be the morphometries most important for determining formation material, and basin area, fan area, (Hmax-f) and compactness coefficient (Cirb) were the most important characteristics for determining erosion rates. The GMDH algorithm predicted the fan formation materials and rates of erosion with high accuracy (R2 = 0.94, R2 = 0.87). [ABSTRACT FROM AUTHOR]

Soil labile organic carbon (LOC) is a valuable and sensitive parameter of the changes in soil carbon (C) pools and further affects soil structural stability. However, the influences of soil-aggregate stability on LOC fractions under erosion conditions are still unclear, especially under the collapsing gully area of south China. Soils of five positions of collapsing gully erosion, including the upper catchment (UC), collapsing wall (CW), colluvial deposit (CD), scour channel (SC) and alluvial fan (AF) from Acric Ferralsols were investigated and sampled. Soil aggregate stability and LOC fractions were measured and analyzed. Soil water-stable aggregate and passive C (passive-C) contents significantly increased by 67–76% and 8.7–13.0% at the UC, CW, CD and SC positions, respectively, while soil labile C (labile-C) content was lower at these positions as compared to the AF position (p < 0.05). Moreover, the UC position's soil C pool management index (CPMI) significantly increased by 37–40% compared to CW, CD, SC and AF soils, indicating that the soil of the UC position had a more stable C pool due to its stronger structural stability. SOC, silt, and amorphous iron oxide (Fea) contents significantly contributed to aggregate stability. We demonstrated that the depletion of soil aggregate stability could result in the decreases in soil LOC fractions, while soil properties of the OC but not the LOC pool regulated aggregate stability and thus affected soil structure across different collapsing gully erosion positions in the subtropical Acric Ferralsols region of south China. This study contributes to developing strategies to prevent soil erosion and improve global C cycle and soil quality, which could be beneficial to strengthen soil and water conservation, and improve soil fertility (e.g., SOC) and vegetation recovery, such as tea and tobacco. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility (MS) of the Quaternary long‐term mid‐latitude Maros fluvial fan (Pannonian Basin) was recorded to understand the stratigraphical features of source‐proximal fluvial depositional settings. Three fully cored 500‐m‐deep boreholes were sampled at 0.5‐m intervals; low‐field and frequency dependent MS were measured, and complementary hysteresis and SEM‐EDAX investigations were performed on selected samples. Logged susceptibility data were also used to log correlations established by a simultaneous comparison of wireline log and laboratory measurements. Time‐series analyses of the susceptibility records reveal a ~41‐ka and ~100‐ka cyclicity. Towards the source‐distal sections the intensity of the ~41‐ka cycles decreases, while that of the ~100‐ka cycles remains strong. Stratigraphical and spectral similarities were observed between the Maros fluvial fan and Chinese loess records; however, based on complementary magnetic data, the magnetic phase of the Maros Fan sections is related to the detrital magnetite that originates from the catchment during early postglacial permafrost degradations. The amplification of the ~41‐ka cycles can be attributed to the very high susceptibility values in source‐proximal settings and to the special stratigraphical feature of the distributive fluvial systems. This comprises the increased avulsion frequency on the fluvial fans in 'glacial recession periods', in concert with the 'early postglacial' occurrence of the permafrost‐related magnetite originating from the catchment. As a local phenomenon, this is significant since it records the obliquity‐driven variations in permafrost development in a catchment. However, fluvial and alluvial fans are widespread depositional landforms within the Eurasian mountain range and were possibly the same during the Quaternary deglaciations. Thus, obliquity‐driven magnetic susceptibility variations in source‐proximal fan deposits attached or adjacent to regions of loess deposition should also be considered when scanning for potential source material of aeolian deposits. [ABSTRACT FROM AUTHOR]

The article presents the stages of development of the alluvial fan of the Stryi River (tributary of the Dniester River), which is the largest alluvial cone in the foreland of the Eastern Carpathians. The alluvial fan has a diverse morphology and complex structure, and its formation is the result of the accumulation and erosion activity of several rivers. In order to reconstruct the evolution of the alluvial fan, geological cross-sections of the Stryi, Svicha and Dniester river valleys were made on the basis of archival drillings and field research. The stratigraphy of the alluvial fills is based mainly on morphological (morphostratigraphic) criteria and the correlation of terrace levels with those of adjacent areas. Fluvial sediments from the Late Glacial and Holocene were dated by the radiocarbon method, which allowed the determination of the age of fan dissection. The main factor controlling the course of accumulation and erosion on the alluvial fan was climate change. The accumulation of alluvial covers was preceded by phases of erosion, which generally fell at the end of the glacial periods (late glacial) and the beginning of the interglacials. Differences in the depth of dissection of the strath and the thickness of the accumulated alluvial sediments in the northern and southern parts of the fan may be the result of different tectonic movements and/or the transport capacity and size of river discharges. In the Late Glacial (Alleröd-Younger Dryas) and the Early Holocene the alluvial fan was dissected to a depth of 10-15 m due to the erosion of the Stryi and Dniester rivers. [ABSTRACT FROM AUTHOR]

Groundwater nitrate vulnerability in alluvial plains in agricultural areas is characterized and controlled by the distribution, sources, and fate of nitrate, which are influenced by a combination of land use and landform sedimentary types. Determining the relative importance of factors and understanding the combined action of multiple land uses and sedimentary types are important for controlling groundwater nitrate pollution in such areas. The Baiyangdian watershed has a variety of landform types (proluvial/alluvial fans and plains, river belts, etc.) and land use types (agriculture, woods, residential, etc.) and was selected as the study area. Water chemical analyses and stable isotopes were used to identify the distribution characteristics and sources of nitrate, and the Depth to water table, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and hydraulic Conductivity (DRASTIC) model was used to assess the vulnerability. The results show that nitrate concentrations are highly variable. 19.1% of nitrate concentrations exceeded the WHO drinking water limit, having a mean of 30.3 mg/L. Nitrate concentrations vary greatly across landform sedimentary types under the same land use. The results of the relative weight calculations showed that the contribution of landform and land use type to groundwater nitrate concentration was 67.4% and 32.6%, respectively. The distribution, source and fate of groundwater nitrate are mainly controlled by landform types. Proluvial and alluvial-proluvial fans has "very high" and "high" vulnerability and nitrate levels, with chemical fertilizers being the main source. Alluvial and flood plain has "low" and "very low" vulnerability and nitrate levels, where manure and sewage are the major sources. River belts, lakes and depressions are in the "medium" vulnerability class, where wastewater discharges result in high local nitrate levels and reduction environment are conducive to avoiding nitrate pollution. The study contributes to the management of land and water resources in similar environments. [ABSTRACT FROM AUTHOR]

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We examined the stratigraphy of alluvial fans formed at the steep range front of the Southern Alps at Te Taho, on the north bank of the Whataroa River in central West Coast, South Island, New Zealand. The range front coincides with the Alpine Fault, an Australian‐Pacific plate boundary fault, which produces regular earthquakes. Our study of range front fans revealed aggradation at 100‐ to 300‐year intervals. Radiocarbon ages and soil residence times (SRTs) estimated by a quantitative profile development index allowed us to elucidate the characteristics of four episodes of aggradation since 1000 CE. We postulate a repeating mode of fan behaviour (fan response cycle [FRC]) linked to earthquake cycles via earthquake‐triggered landslides. FRCs are characterised by short response time (aggradation followed by incision) and a long phase when channels are entrenched and fan surfaces are stable (persistence time). Currently, the Te Taho and Whataroa River fans are in the latter phase. The four episodes of fan building we determined from an OxCal sequence model correlate to Alpine Fault earthquakes (or other subsidiary events) and support prior landscape evolution studies indicating ≥M7.5 earthquakes as the main driver of episodic sedimentation. Our findings are consistent with other historic non‐earthquake events on the West Coast but indicate faster responses than other earthquake sites in New Zealand and elsewhere where rainfall and stream gradients (the basis for stream power) are lower. Judging from the thickness of fan deposits and the short response times, we conclude that pastoral farming (current land‐use) on the fans and probably across much of the Whataroa River fan would be impossible for several decades after a major earthquake. The sustainability of regional tourism and agriculture is at risk, more so because of the vulnerability of the single through road in the region (State Highway 6). [ABSTRACT FROM AUTHOR]

The current study included the Bai Hassan Formation (Upper Bakhtiari) in the Zakho area of northern Iraq. Depending on the grain size class, structures, degree of rounding, sorting, and some other detailed field observations. This formation was divided into eleven lithofacies which are matrix-supported conglomerate, clast-supported conglomerate, laminated sandstone, sandy gravel, planar cross-bedded conglomerate, interbedded siltstonemudstone, gravely sandstone, interbedded sandstone-conglomerate, lime matrix-supported conglomerate, and caliche lithofacies. These lithofacies are distributed into six coarseningupward cycles consisting of complete and incomplete cycles, and these lithofacies include sedimentary structures such as imbrication pebbles, bedding plain, load cast, and gravely cross-bedding. The environment of the Bai Hassan Formation represents conjunctive alluvial fan with possible internal lake environments. The study includes the determination of source areas such as sedimentary, igneous, and metamorphic rocks. [ABSTRACT FROM AUTHOR]

The NNW‐striking Mongolian Altai is a Late Cenozoic dextral strike–slip deformation belt affected by the far‐field stress caused by the collision between India and Eurasia. The Tsambagarav Massif is bounded by faults, has a triangular plan shape, and attains the highest elevation of the belt. This massif is adjacent to the central segment of the Hovd fault, which is the largest fault in the Mongolian Altai. Here, we use 10Be surface exposure dating, radiocarbon dating, and paleoseismic trenching to reveal deformation patterns and Quaternary slip rates for two range‐bounding faults: the Tsambagarav dextral reverse fault and the Lower thrust fault. The Lower thrust exhibits thrusting motion along the low‐angle structural fabric of the basement rock and cuts Quaternary alluvial fan deposits, vertically offsetting their surfaces by 3.9–5.1 m, with fault scarps extending several kilometres along‐strike. The Tsambagarav dextral reverse fault is characterized by strike–slip motion along the high‐angle structural fabric of basement rock. Various surface deformation features indicate recent dextral strike–slip, including displacements of Late Quaternary moraine by ~50 m. Dividing the measured displacements by 10Be surface exposure ages of alluvial fan surfaces (for the Lower thrust) and moraine (for the Tsambagarav dextral reverse fault) gives a reverse slip rate of 0.3–1.7 mm/yr for the Lower thrust and a horizontal slip rate of 1.7–2.6 mm/yr for the dextral reverse fault. Radiocarbon ages of animal bones in a pond deposit accumulated along an associated tensional crack indicate that the last earthquake that caused a surface rupture occurred between 1924 and 1708 cal yr BP. Our study suggests that strain partitioning has occurred on the faults of the Tsambagarav Massif. [ABSTRACT FROM AUTHOR]

Uplift of the Tian Shan range modified regional climate during Cenozoic aridification in Central Asia. This study presents facies analyses and Neogene oxygen and carbon isotopic records from magnetostratigraphically dated terrestrial sedimentary sections on the southern side of the intermontane Issyk‐Kul basin in the Kyrgyz Tian Shan and 26Al/10Be isochron burial ages from the southern and eastern sides of the basin. The δ18O and δ13C data show a positive ca. 2‰ shift in values between ca. 8 and 7 Ma and a change from a negative to a positive trend. This change is attributed to the upwind growth of the Kyrgyz, Kungey and Trans Ili (Zaili) ranges, which diverted the westerlies, thereby changing the Issyk‐Kul basin from a windward to a leeward position, enhancing aridification and establishing the modern‐day spring and summer precipitation regime within the basin. Two 4 to 5 Ma 26Al/10Be isochron burial ages constrain the onset of Sharpyl Dak deposition on the eastern side of the basin; southward paleocurrent directions there suggest the eastward growth of the Kungey range in the Pliocene. Increased subsidence on the southern side of the basin and local tectonically induced river system reorganization led to the commencement of lake formation at ca. 5 Ma, followed by a ca. 2 Ma local depositional hiatus. The transition from sandstones of the Chu sedimentary group to conglomerates of the Sharpyl Dak group, marking a change from fluvial‐alluvial deposits to a proximal alluvial fan, is dated at 2.6–2.8 Ma by 26Al/10Be isochron burial dating on the southern side of the basin, driven either by tectonics or Northern Hemisphere glaciation. This study concludes that the late Miocene–Pliocene northward growth of Tian Shan significantly altered environmental conditions within the range, preventing the moisture‐bearing westerlies from reaching the intermontane Issyk‐Kul basin and promoting lake formation and expansion. [ABSTRACT FROM AUTHOR]

From Middle-Late Triassic continental deposits of the Timezgadiouine Formation (Argana Basin, Morocco), 17 lithofacies are identified, with alluvial fan, fluvial, floodplain and lacustrine associations. Invertebrate traces include Archaeonassa fossulata, Arenicolites isp., cf. Arenituba, Beaconites isp., cf. Camborygma, Cruziana problematica, Diplocraterion isp., Fuersichnus isp., Helminthoidichnites tenuis, Lockeia isp., Palaeophycus striatus, Palaeophycus tubularis, Planolites isp., Rusophycus carbonarius, Scoyenia gracilis, Skolithos isp., Spongeliomorpha carlsbergi, Taenidium isp. and Taenidium barretti. Additionally, rhizoliths were observed. Six ichnoassemblages were distinguished: overbank facies with (1) Rhizolith ichnoassemblage in a low-energy floodplain environment and (2) Scoyenia-Palaeophycus ichnoassemblage in crevasse splay deposits. The fluvial ichnoassociation is of moderate ichnodiversity consisting of the following assemblages: (3) Arenicolites, developed under higher flow velocities of active channels, (4) Taenidium-Scoyenia, formed by the colonisation of inactive channels, (5) Arenicolites-horizontal meniscate burrows, reflecting a rapid transition between active and abandoned channels and (6) Lockeia-vertebrate footprint, formed in littoral lakes. The Aglegal and Irohalene members indicate climatic shifts between arid dry, semiarid and subhumid in a dryland river environment. The sudden onset and the high frequency of lacustrine deposits in the lower Irohalene Member point to a rapid climate change from dry to intermittent wet and dry. This change is discussed in terms of the Carnian Pluvial Event. [ABSTRACT FROM AUTHOR]

Cenozoic strata on the Great Plains are the products of a long-lived, continental sediment routing system, and yet strikingly little is known about these ancient rivers. This article details the discovery of ~3100 fluvial ridges--erosionally inverted alluvial-fan, channel-fill, channel-belt, and valley-fill deposits--extending from the Rocky Mountain front to the eastern margin of the Great Plains. The direct detection of these channel bodies reveals new insights into late Eocene-Pliocene drainage evolution. Late Eocene-Oligocene streams were morphologically diverse. Alluvial fans adjacent to the Rocky Mountain front changed eastward to parallel or downstream-divergent, fixed, single-thread, straight to slightly sinuous (S = 1.0-1.5) streams <50 m in width. At ~100 km from the Rocky Mountain front, streams became sinuous and laterally mobile, forming amalgamated channel bodies as much as 3 km in width. Streamflow in all these systems was highly dispersed (southeast to northeast) and temporally variable. These characteristics reveal a nascent Great Plains alluvial apron hosting small, poorly integrated drainages undergoing abrupt changes. By the Miocene, more uniform streamflow generally trended east-northeast. Channel deposits are identifiable 500 km from the Rocky Mountain front. Middle Miocene valley fills gave way to fixed, multithread channels a few kilometers in width by the late Miocene. These patterns evince a mature alluvial apron hosting bigger rivers in well-integrated drainages. We interpret the systematic changes between fixed and mobile channel styles to record spatially and temporally variable aggradation rates. The widening of channels in the late Miocene likely reflects increased discharge relating to wetter climates upstream or the integration of once-isolated Rocky Mountain drainage basins into a continental-scale drainage system. [ABSTRACT FROM AUTHOR]

Despite recent advances in mapping and dating alluvial fans, due to the availability of high-resolution remote sensing data and Quaternary dating techniques, quantifying surface features in remote sensing data remains a challenge. Surface roughness is a time-dependent feature under stable conditions, which indicates the relative age of alluvial fans in a hyperarid environment. Although surface roughness can be quantitatively inferred from remote sensing data, determining surface roughness in a uniform index remains a complex problem. Here, we used the normalized backscatter intensity (NBI) from high-resolution ALOS PALSAR data to quantify alluvial fan surface roughness, which is further used to quantitatively map alluvial fans. We established a robust power-law relation between the NBI value (R) and the in-situ age (T) as measured with independently dated alluvial fans. Based on the R-T relation, it can be further to apply the R measurement to T estimates as old as ∼540 ka with an average uncertainty of ∼25% on a regional scale. The NBI value, independent of atmospheric conditions and sensitive to surface roughness variability, is an effective criterion for quickly distinguishing alluvial fans and performing age estimation. We propose that insolation weathering is an important physical weathering pattern in the Dead Sea area, which mainly controls the surface roughness in this hyperarid region. [ABSTRACT FROM AUTHOR]

From 300 BC to AD 300, the city of Pergamon underwent a profound transformation that impacted the rural settlement patterns and the concomitant geomorphodynamics. We present a geoarchaeological study in a long-term settled catchment in the Pergamon micro-region to disentangle the Holocene geomorphodynamics and triggering factors, for example, climate change and human activity. The analyses of eight radiocarbon-dated sediment profiles from the Tekkedere alluvial fan and its catchment indicate four principal sedimentation phases. Phase 1 (ca. 6.2 to 5–4 ka) is dominated by the floodplain aggradation of the receiving Bakırçay River, which is followed by the formation of floodplain soils (phase 2). Substantial geomorphodynamic changes occurred around 4 ka (phase 3), when the edge of the floodplain was buried by fan sediments of the tributary Tekkedere creek. This is attributed to supraregional aridization and rapid climate change events, superimposed by the onset of local human activities. Repeated cycles of coarse- and fine-textured fan sediments with age inversions after ca. 3.8 ka and valley infills younger than 1300 yr BP indicate the strong erosion and redeposition of sediments in phase 4. These increased geomorphodynamics may coincide with the changing settlement pattern and thus reflect human–environment interactions. [ABSTRACT FROM AUTHOR]

The Cantwell Formation of the central Alaska Range provides a robust archive of high-latitude, Late Cretaceous depositional systems and paleo-floral/faunal assemblages. Our stratigraphic analysis defines two mappable members. The lower member (1500–2000 m thick) represents vegetated alluvial fan and braided fluvial systems that transition up-section to fluvial–estuarine systems that drained into an inland continental seaway. The upper member (~2000 m thick) represents estuarine–marginal marine and lacustrine systems. Previous paleontological studies demonstrate that the Cantwell basin was populated by various dinosaurs, fishes, bivalves, birds, and marginal marine micro-organisms. Integration of new and published geologic mapping allows for reconstruction of depositional systems at the basin scale and provides additional paleogeographic context. The northern basin margin was defined by a previously unrecognized south-verging thrust belt, whereas the southern margin of the basin was defined by a north-verging thrust belt inboard of an active magmatic arc. Sediment sources interpreted from U-Pb detrital zircon geochronology included the coeval magmatic arc and older Cretaceous plutons, and Proterozoic–Mesozoic strata exhumed along the basin margins. Results of our study provide a depositional, stratigraphic, and structural framework that may serve as a guide for future paleontological and paleoclimatic investigations of Late Cretaceous Arctic environments of the Cantwell basin. [ABSTRACT FROM AUTHOR]

Pliocene (?)—early Pleistocene shallow marine deposits, varying from gravel to sand to clay, characterize the southernmost sector of the Valdichiana Basin, between Orte and Città della Pieve, across Tuscany, Umbria and Latium (Central Italy). Facies associations, referring to the evolution of a river-fed coast, with a sensible facies heteropy, and a sub-environment articulation, both across and alongshore, have been recently described. Although the main part of the territory responds to a wave-dominated coastal model, a clear fluvial sediment origin and the presence of localized river mouths have also been documented. Nearshore is mainly represented by interbedded sand and gravel beachface to upper shoreface deposits, in which both a mouth bar organization and a lateral distribution of gravel beaches are recognizable. Sediment origins largely depend ondebris flow processes, related to small alluvial fans/fan deltas. In constrained areas, debris flow and current continental deposits occur, referring to coalescent alluvial fans, organized as a smoothly seaward-dipping piedmont band, drained by shallow braided channels. This roughly organized fluvial system feeds a coastal area, with a fandeltabuild-up. The as-described fan delta and beach systems are characterized by a smooth seaward morphology, according to models resembling, on a coast-transverse profile, the shelf-type fan delta. Although the proposed models differ from each other's, with respect tothe shelf-type one, this is mainly on a lateral facies distribution. [ABSTRACT FROM AUTHOR]

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