Lake Level Fluctuations Research Articles

A Paleoenvironmental Reconstruction of Lake Vrana on the Island of Cres (Croatia) Based on the Geochemistry and Mineralogy of the Late Pleistocene and Holocene Sediments

A 7.4 m long sediment core has been retrieved from the central part of Lake Vrana on the island of Cres to reconstruct the paleoenvironmental conditions. Lake Vrana is the deepest freshwater lake in Croatia, located in the karst region of the eastern Adriatic coast. A dated sediment sequence in Lake Vrana of 4.4 m has spanned the past 16.4 kyr, and it featured a dynamic sediment deposition until the beginning of the Holocene, including strong sediment input and supply to the lake by runoff sediments of dolomitic origin from the catchment in the period 16.4–14.4 cal kyr BP. High organic carbon content, which originates from mixed terrestrial and aquatic origins in the periods 14.4–13.3 cal kyr BP and 12.7–11.7 cal kyr BP, indicates fluctuating lake levels in shallow water environments during the Late Glacial to Holocene transition. The Holocene sequence indicates the development of more stable conditions and continuous sediment deposition, characterized by an increasing trend of siliciclastic sediments delivered into the lake during the early Holocene (11.7–10 cal kyr BP) and dominantly from 8 to 4.4 cal kyr BP, indicating enhanced input and erosion, which coincides with the humid and pluvial period recorded in the central Mediterranean region. It is followed by sediments with high organic carbon content between 4.4 and 1.6 cal kyr BP, which points to higher lake productivity. Calcite sedimentation prevailed between 1.6 to 0.4 cal kyr BP, indicating stable deeper-lake conditions. Predominantly, siliciclastic sediments from 0.4 to 0.1 cal kyr BP pointed to erosion during the Little Ice Age (LIA), with enhanced precipitation and sediment discharge from the catchment. The re-establishment of calcite sedimentation has been observed over the last 100 years.

Formation mechanism and oil-bearing properties of gravity flow sand body of Chang 63 sub-member of Yanchang Formation in Huaqing area, Ordos Basin

Abstract Gravity flow sand body is an important reservoir for deep water deposition. The in-depth study of its formation mechanism and oil enrichment law can provide important guidance for oil and gas exploration in deep water areas. In this article, taking the deep-water gravity flow sand body of the Triassic Chang 63 sub-member in the Huaqing area as an example, the identification characteristics, formation mechanism, and oil-bearing characteristics of the gravity flow sand body are systematically discussed. The results show that sandy debris flow, turbidite flow, and mixed event flow present different superposition combination modes on vertical gravity flow deposition. The lithofacies of the gravity flow sandstone complex are mainly affected by lake level fluctuation, provenance supply, and hydrodynamic conditions. According to the formation conditions, sedimentary types. and distribution characteristics of deep water gravity flow sand bodies, a three-dimensional sedimentary mode of deep water gravity flow sand bodies is established. It is found that the physical and oil-bearing properties of the sandy debris flow sand body are better than those of the turbidity flow sand body. The reason is that the proportion of debris in the sand body of sandy debris flow is high, and the content of debris particles is generally greater than 70% according to the statistics of thin sections, which is conducive to the formation of pores. Second, sandy debris flow belongs to block transport, and the mixing of lithology is not sufficient in the process of block flow transport, so some pores will be preserved. Finally, gravity flows, which are dense at the beginning, become less dense later as detrital sediments unload, allowing them to be transported to distant regions. Therefore, the monolayer thickness of the sandy debris flow sand body is large (generally greater than 0.5 m), and the particle size of the debris ranges from 0.03 to 0.3 mm. Finally, the physical and oil-bearing properties of the sandy clastic flow sand body are better than those of the turbidity flow sand body.

Paleoenvironmental reconstruction of Lake Van and Lake Erçek over the last millennium using varved sediments (Eastern Türkiye)

Detailed lithological and geochemical studies of the bottom sediments were conducted based on the original sampling of brackish adjacent lakes: Lake Van and Lake Erçek in Eastern Anatolia, Türkiye. Seasonal variations in the accumulation of weather-driven element content were determined using high-resolution Synchrotron Radiation X-Ray Fluorescence (SR-XRF) analysis of the annual layers in the solid prepare. The results were utilized to approximate the regional paleo-temperature of both lakes and the water level of Lake Van. Visual counting of the varve as well as annual oscillation of measured geochemical series was employed to create a time scale. The element content series were synchronized with recent changes in external climatic environments and lake water level fluctuations. Subsequently, the geochemical series were transformed into climate units, using calibration on synchronous meteorological data. Finally, the original quantitative reconstruction of the regional climate variations was performed over the last millennium period with annual time resolution; for Lake Erçek (840 years ago) and Lake Van (1300 years ago). It was revealed that the sediments of these adjacent lakes (Lake Van and Lake Erçek), located 30 km apart from each other, provided synchronous responses to regional environmental changes, which confirmed the reliability of the reconstructions.

Evolution and morphological diversity of the genus Diploneis (Bacillariophyta) in Lake Malawi, with description of six new species

ABSTRACT Lake Malawi, one of the world’s oldest and most important freshwater systems, harbours a remarkable biotic diversity partly due to variable fluctuations in climate and lake level. Over time, these fluctuations have contributed to the emergence and development of different ecological niches and microhabitats that have facilitated diversification within the lake. Despite our extensive knowledge of different animal groups, the evolutionary history of species-rich diatom groups in Africa and, particularly, in Lake Malawi has yet to be studied. Here, we used a combination of morphological, molecular, and paleontological data to assess the species richness and evolutionary processes of the diatom genus Diploneis in this lake. The comprehensive dataset revealed four putative new endemic species from modern and two apparently extinct Diploneis species from the fossil record of the lake, described here as new to science. Morphological analyses showed that all these new species exhibit remarkable differences and unique morphological patterns that were recently discovered in Diploneis species from nearby Lake Tanganyika. Molecular phylogenetic analyses revealed that the four new species now living in Lake Malawi are nested within a clade of Lake Tanganyika Diploneis species but do not form a monophyletic group. This suggests that the new Lake Malawi Diploneis species are derived from one or more Tanganyikan ancestors and that more than one colonization event probably occurred. However, further analyses are needed to elucidate their origin.

Modern distribution of Cladocera in lakes of northern China and western Mongolia and its environmental implications

Cladocerans are widely distributed in aquatic ecosystems and are sensitive to environmental changes; hence, they are commonly used to trace ecological changes in aquatic environments. However, the distribution of cladocerans in northern China is poorly known. We investigated the occurrence of cladocerans in 136 water bodies (including lakes and reservoirs), with varying hydro-chemical and climatic gradients, in northern China and western Mongolia. We identified 38 cladoceran taxa in the surface sediments of 88 different water bodies, while the remaining lakes, mainly saline, had no cladocerans. The spatial distribution characteristics of cladoceran species and the environmental factors determining their community composition were investigated using canonical correspondence analysis. The results demonstrate that water depth, trophic status, and water salinity were the top three variables influencing the composition of cladoceran taxa. Transfer functions between the surface sediment cladocerans and lake level and nutrient (NH4) levels in 62 lakes (26 lakes lacked environmental data) were established via multivariate statistical analyses. Using the subfossil cladocerans of Jili Lake, lake level and nutrient values were reconstructed for the past 100 years. The results agree overall with the observational data, and they reveal that the changes in the cladoceran community reflected mainly lake level fluctuations before 1988 CE, and mainly nutrient changes thereafter. Our research clarifies, for the first time, the environmental significance of modern Cladocera in the lakes of northern China and western Mongolia, and it provides a foundation for the future reconstruction of long-term changes in the ecological environment of lakes.

Lake level fluctuations and varve preservation – The sediment record from Lake Suminko (Poland) reflects European paleoclimatic changes

We present a reconstruction of Holocene lake-level fluctuations at Lake Suminko, a eutrophic hardwater lake in northern Poland. The lake contains annually laminated (varved) sediments, forming a unique archive of past hydroclimatic variability. Employing a combination of sedimentological and geochemical methods, we demonstrate that sediment core sections with well-preserved varves and lower Ca/Fe ratios correspond to periods of higher water levels associated with colder and wetter climatic conditions. We identify twelve periods of lake level high stands, consistent with other lake sediment records from western Poland and Europe, as well as with North Atlantic IRD events. Pollen data and geochemical proxies confirm negligible human impact on the lake during most of the Holocene, except for the last 500 years when accelerated soil erosion related to landscape opening and agricultural activities occurred. Therefore, we conclude that Holocene lake-level fluctuations at Lake Suminko are primarily controlled by climatic conditions regulating water availability and groundwater supplies to the lake. Our study also highlights the potential of varve preservation as a useful indicator of lake-level changes.

The Lake Paravani archive – a contribution to the late Quaternary landscape evolution of the Lesser Caucasus (Georgia)

Lake Paravani, located on the volcanic Javakheti Plateau in the central part of the Lesser Caucasus at 2073 m a.s.l., forms a unique geo‐bio‐archive for palaeoenvironmental reconstructions in this remote region. Based on sediment cores from the southwestern part of the lake we expand the existing palynological and sedimentological records beyond the Last Glacial Maximum (LGM). For the first time, it is possible to reconstruct the palaeoenvironment in this part of the Lesser Caucasus back to c. 28 cal. ka BP. Our study shows that until 16 cal. ka BP glacial conditions dominated (Phase I) in the region; there is, however, proof that the lake already existed during the LGM. In the following transitional Phase II from 16 until 6 cal. ka BP, cold and arid conditions with sparse steppe vegetation and a lowered lake level prevailed. Around 10 cal. ka BP, tree pollen started to expand while herbaceous pollen, especially Chenopodiaceae, declined. In Phase III, since 6 cal. ka BP, mixed forest probably represented the Holocene climatic optimum. Fluctuating lake levels indicate shifting climatic conditions. The minor changes of arboreal pollen hin the uppermost part of Phase II may be an indication of human activity. The more humid, vegetation‐rich environment and mild climate around 4.5–2 cal. ka BP correlate with the expansion of the Late Bronze Age settlements in this area (from ~3.5 cal. ka BP/~1.5 ka BC). The proliferation of sites on the plateau, along with even higher‐altitude sites possibly dating to the same period, may indicate that this climate amelioration played an important role in enabling more sustained human occupation. The results extend the record on Lake Paravani by several millennia beyond the LGM and complement the palaeo‐lake reconstructions of the wider region, e.g. at Lake Van (Türkiye) or Lake Sevan (Armenia).

Composite water value: A way forward to balance the development and protection of transboundary lakes

Transboundary lakes are shared by multiple administrative regions. The key to balance the development and protection of transboundary lakes is to properly measure the value of water resources. Most of previous studies on the measurement of lake water resources value have not fully considered the ecosystem service function. This paper proposes a new concept “composite water value” to measure the value of transboundary lakes by integrating the external runoff value and the internal runoff value of water resources. The study constructs a composite water value measurement system for transboundary lakes, further analyzes its influencing factors,and applies the system to the case of Nansi Lake, a representative transboundary lake in eastern China. The results show that: (1) The composite water value of lakes is influenced by various factors, including industrial structure, water withdrawal, and water use methods, which impact the external runoff water value; meanwhile, the composite water quality and fluctuations in lake level are closely associated with the internal runoff water value. From 2008 to 2021, the average annual composite water value of Nansi Lake was 39.628 billion yuan, exhibiting a "rising-falling-fluctuating rising" trend due to pollution control policies, reduced precipitation, and enhanced water-saving technologies successively. (2) From a long-term perspective, it is necessary to focus on the internal runoff water use value of lakes. The internal runoff water value of Nansi Lake has been over 75% of the composite water value, and flood storage and water conservation are important manifestations of its ecosystem service value. (3) The external runoff water value of lake is closely related to the internal runoff water value, and relevant departments need to consider the balance between the water withdrawal of multiple cities along the lake and the retained water volume of the lake to achieve the maximum benefit of composite water value.

Evidence of lake-level fluctuations during the late Holocene based on diatoms from Lake Vransko, Cres Island (north-central Mediterranean)

An investigation of Lake Vransko, located on the island of Cres in the Adriatic Sea, was performed in order to reconstruct the palaeoenvironmental changes that occurred during the late Holocene, based on diatoms. Fluctuations in the lake level were mostly driven by the intensification of climatic oscillations (wet periods during North Atlantic Oscillation intervals and summer drought during Azores High intervals) and anthropogenic influences (e.g. the extraction of drinking water). The anthropogenic impact of local deforestation is encountered, associated with a peak in phosphorous in the deeper parts of the lake cores. As a consequence of these impacts ten diatom abundance zones (DZs) and the water/sediment interface (WSI) were recorded from the deeper core (CS-51) and two from the shallower (CS-52) core, along with the WSI, based on which an abrupt fluctuation in the level of the lake was interpreted. A dominance of Epithemia adnata in the deeper core, and Gomphonema pumilum in the CS-51, and in the CS-52 indicated a shallow phase connected with the summer drought recorded in the lake. A dominance of Amphora inariensis, Pseudostaurosira spp., Cyclotella spp. and Pantocsekiella ocellata in the rest of the cores indicated deeper, more alkaline lake conditions during the wet periods. The DZs accord with depth variations in Adriatic coastal lakes that are key sites of more extreme recent changes in the local climate.

Sedimentary Evolution Laws and Main Controlling Factors of the Nenjiang Formation in the Songnan Da’anbei Area, China

Shallow-water deltas serve as a critical area for the exploration and development of terrestrial lacustrine oil and gas reservoirs. Current research on oil and gas exploration and development in China’s terrestrial lacustrine basins primarily focuses on their delta front facies zones. Despite extensive discussions on the sedimentary characteristics of shallow-water deltas by predecessors, there is a lack of comprehensive analysis on the combined effects of dynamic factors such as climate change, lake level fluctuations, and sediment supply. This paper, through a detailed examination of 12 core samples and integrating data from 493 exploratory, appraisal, and development wells in the study area, establishes a stratigraphic correlation framework using well–seismic integration techniques. It identifies two main sedimentary facies types in the southern Da’anbei area of the Songliao Basin: shallow-water deltas and lake facies, which can be further subdivided into four sub-facies and nine microfacies. Two depositional models for the shallow-water deltas of the Southern Songliao Nenjiang Formation are established: a deeper water background with channel-river mouth bar sequences forming the delta front framework and a shallower water background with channel-sheet sand sequences forming the delta front framework. This paper also discusses the controlling effects of paleoclimate, sediment supply, and lake level changes on sedimentary evolution, providing a scientific basis for the exploration of lithologic oil and gas reservoirs in the Nenjiang Formation of the study area and the deployment of horizontal wells.

Middle to Late Holocene lake level variations recorded by shoreline tufa of Longmu Co Lake, northwestern Tibet Plateau

Tufa deposits have significant potential for reconstructing past lake-level fluctuations. Here, we conducted U-Th dating of tufa deposits exposed along the shoreline of Longmu Co Lake in the northwestern Tibetan Plateau to reconstruct its water level history during the middle-late Holocene. Our data demonstrate that Longmu Co Lake reached its highest level (61 m above the present level) at around 7.4 ka in response to the strengthened Indian Summer Monsoon and increased glacial meltwater; its lake level subsequently decreased due to solar insolation-induced decline in summer monsoon and glacial meltwater. Moreover, we find that the lake level experienced an abrupt decline at ~2.2 ka with a maximum amplitude of 13 m, probably owing to the rapid cooling of the local climate. The δ18O and δ13C of Longmu Co tufa also show a covariance trend, which supports the regional climate change reflected by the lake level fluctuation of Longmu Co. Additionally, we observed an inverse correlation between initial δ234U content in tufa and lake level variation, suggesting that initial calcium δ234U can serve as a proxy for reconstructing environmental changes. Our study therefore implies that lake tufa as a reliable archive for accurately reconstructing lake level changes.

Impacts of hydrologic management on the eutrophication of shallow lakes in an intensive agricultural landscape (Saskatchewan, Canada)

Abstract Hydrologic management of shallow lakes is often undertaken to prevent fluctuations in lake level, and to ensure sufficient water volume for economic, domestic, and recreational uses, but there is inconsistent evidence of whether lake‐level stabilisation through hydrological management promotes or hinders eutrophication. Here we used multi‐proxy paleolimnological assessments of water quality (sedimentary carbon, nitrogen, total phosphorus, fossil pigments), and zooplankton community ecology (fossil Cladocera assemblages), combined with Landsat‐derived estimates of lake surface area in two shallow eutrophic lakes, in the Prairies of southern Saskatchewan, Canada, to quantify how 8 decades of contrasting hydrological management strategies (continuous or intermittent) affect primary production and phytoplankton composition. Analysis revealed that irregular hydrological management of Pelican Lake led to sharp increases in primary production concomitant with lake‐level decline. In contrast, continuously managed Buffalo Pound Lake, a drinking water reservoir for regional cities, exhibited slow, persistent eutrophication over decades despite active regulation of water levels. In both lakes, strong correlations of δ 15N values with pigments from diazotrophic cyanobacteria (canthaxanthin) showed that N2‐fixation increased during eutrophication irrespective of the timing of change. Finally, variation in fossil cladoceran density and composition reflected changes in pelagic and littoral habitats (e.g., reduced macrophyte cover) due to changes in both lake level and water quality. Basin comparison shows that while hydrologic management can moderate water quality degradation due to lake‐level change, it does not prevent eutrophication when nutrient influx remains high. Given that regional water availability is forecast to decline in coming decades, we anticipate that continued hydrological management will be unavoidable and will be unable to improve water quality unless nutrient influx is also controlled.

The anatomy and stacking pattern of palustrine-dominated carbonate sequences from the Cengle Plateau, Paleocene, SE France: A multi-scalar approach

An integrated approach combining petrography, photogrammetry, geochronology, SEM, and geochemical data was utilized to analyze lithofacies, stacking patterns, and lateral facies variations, and to interpret environmental dynamics during the deposition of carbonates from ‘La Barre du Cengle’ in the Early Paleogene. Located in the SE of France, the elliptical Cengle Plateau stretches 7 km from east to west and is 2 km wide, featuring cliffs ranging in thickness from 20 to 35 m. These cliffs showcase grayish, beige, and pinkish limestones dominated by palustrine facies, forming part of the ‘Calcaire de Saint Marc’ Formation of the Arc Basin. Sedimentary deposits within this interval were repeatedly subjected to subaerial exposure due to fluctuations in lake levels driven by climate, resulting in the organization of elementary sequences at decimetric to metric scales, which stack up into small-scale sequences at the decametric order. Deposition occurred under mainly subarid climatic conditions, with paleogeographic variations in the basin corresponding to changes in lake base levels over time and space. At least four frequencies of base level variation are present: very high and seasonal frequency, responsible for the formation of palustrine facies; high frequency, which generates the elementary sequences; medium frequency, which leads to the formation of the small-scale sequences; and low frequency which corresponds to the deposition of the entire set of limestones that form the Cengle cliff. The transition between lacustrine, palustrine, and pedogenic environments consistently occurs from west to east over time. In the more distal regions, the proportion of lacustrine facies tends to increase, and the thicknesses of the preserved sedimentary record tend to be greater. Conversely, palustrine and pedogenic facies predominate in the more proximal areas, typically resulting in decreased thickness.

Holocene Paleohydrological Changes Reflected in Lake-Level Fluctuations in Lake Annecy (French Pre-Alps): Climatic Significance and Archeological Implications

Lakes are threatened by contemporary climate change and human activities. Paleohydrological records provide important evidence for developing scenarios for future changes in the availability of freshwater resources. This study presents a synthesis of a sedimentological, archeological, and chronological dataset collected from Lake Annecy (eastern France) to reconstruct a lake-level record documenting the whole Holocene. This dataset shows a pronounced minimum in the lake level during the Holocene thermal maximum (HTM) (ca. 9000–7000 cal BP), preceded by a general lowering trend (early Holocene), and followed by a general rising trend (Neoglacial). On both the millennial and centennial scales, the Lake Annecy record appears to match the regional pattern of Holocene lake-level fluctuations established for West-Central Europe. In agreement with other extra-regional paleoclimatic records, it shows the dominant influence of orbital forcing. The high magnitude of the lake-level lowering (more than 5 m) during the HTM, with a 2–2.5 °C difference between the HTM and the pre-industrial mean summer temperatures, suggests possible drastic lake-level lowering phases in the near future depending on the IPCC scenarios following climate change. This would mean dramatic impacts on human activities and the preservation of exceptional archeological remains in regional lake basins.

Sedimentology, depositional processes, and sequence stratigraphy of deep lacustrine fine-grained sedimentary rocks in the lower Oligocene Xiaganchaigou Formation, Qaidam Basin, Northwestern China

Lacustrine deep-water fine-grained sedimentary rocks are characterized by high heterogeneities in lithology and lithofacies stacking patterns, controlled by sediment supply and lake level fluctuation. Despite their vital roles as source and reservoir rocks of unconventional oil and gas play, depositional processes and sedimentary sequence of lacustrine fine-grained sedimentary rocks are poorly understood compared to their extensively studied deep marine counterparts. Here, we studied lithofacies, transportation and depositional processes, depositional environments, and sedimentary cycles of deep-water fine-grained deposits of the Lower Oligocene Xiaganchaigou Formation from cored wells in the western Qaidam Basin. Nine lithofacies that stack repetitively in 6–18 m thick sedimentary cycles are identified based on petrographic observation, geochemical analysis, and scanning electron microscopy. The regressive systems tract of a sedimentary cycle is composed of detrital-rich massive fine sandstone deposited by debris flows and thin-bedded fine sandstone deposited by high-density turbidity currents. The transgressive systems tract is dominated by laminated carbonate-rich mudrock facies deposited by low-density turbidity currents. A complete sedimentary cycle is interpreted to represent a transgressive-regressive cycle controlled by fifth-order lake-level variation. Coarse-grained detrital-rich debrite and high-density turbidite were deposited in the proximal sublacustrine fan and channel during lake-level regression, with sediments mainly supplied by terrigenous siliciclastic input. Carbonate-rich low-density turbidites are deposited primarily in the distal sublacustrine fan during lake-level transgression. Thin-laminated carbonate-rich mudrock facies with high organic matter abundance and well-developed laminae-induced fractures are considered both source rocks and target reservoirs of the upper Xiaganchaigou Formation.

Mixed siliciclastic-carbonate-tuffaceous sedimentation in a rift lacustrine basin: A case study of the Lower Cretaceous Jiufotang Formation in the Luxi sag, Songliao basin

The Lower Cretaceous Jiufotang Formation lacustrine successions in the rift Luxi sag, Songliao Basin are characterized by mixed siliciclastic-carbonate-tuffaceous and organic-rich deposits. Ten facies were recognized and were formed in fan delta, delta, littoral-sublittoral lacustrine and deep lacustrine environments. A depositional sequence characterized by significant changes in facies and lake regime has been defined, and is divided into lowstand systems tract (LST), transgressive systems tract (TST), and highstand systems tract (HST) that are separated by sequence boundaries, initial flooding surfaces, and maximum flooding surfaces, respectively. During the LST, the delta and fan delta deposits covered the marginal area and extended into littoral-sublittoral lacustrine and deep lacustrine environments, respectively. During the TST, the areas of delta and fan delta decreased and lake areas increased, and the carbonate-dominated shoals and mixed siliciclastic-carbonate shorelines occupied the edge of the Majiapu highland belt. During the HST, the lake areas further expanded, and the fan delta deposits extended into deep lacustrine environments and formed deposits of underflows and turbidites. A depositional model in the rift lacustrine Luxi sag is proposed, incorporating the effects of tectonics and sediment supply, climate and carbonate production, hydrodynamic conditions, and lake-level fluctuations. During the LST, the active tectonic movement, high input of siliciclastic sediments, and subaerial volcanic eruptions resulted in the wide distribution of mixed siliciclastic-tuffaceous sedimentation. During the TST, the brackish lake water controlled by periodic dry and hot climate facilitated the carbonate deposition in shallow water, and tractional currents onto the lake shore carried sediments to form the mixed siliciclastic-carbonate-tuffaceous facies. During the HST, more humid climate and increased runoff allowed formation of widely distributed, mostly oil shale-rich deposits, and the gravity flows carried the sediments into the deeper part of basin to form the mixed siliciclastic-carbonate-tuffaceous facies. The depositional model of mixed deposits in this rift lacustrine basin has been proposed here in order to encourage comparison with other similar basins.

Distribution patterns and controlling factors of beach bars in Qinghai Lake, NW China

The significance of beach-bar reservoirs, which are intricately linked to unconventional hydrocarbon reservoirs, has gained increased attention. This study elucidates the complex mechanisms governing the formation, spatial distribution, and morphological characteristics of beach bars in Qinghai Lake, NW China, highlighting the interplay of lake-level fluctuations, wind wave dynamics, sediment provenance, and terrain gradient. Our findings reveal that large-scale lake-level fluctuations primarily dictate the initial formation settings of beach bars, while small-scale fluctuations refine their internal stratification and sedimentary features. Wind wave dynamics play a critical role in defining suitable depth zones for beach bar development, influencing their morphology and resulting in distinct sedimentary characteristics across different lake zones. Furthermore, the study categorizes beach bars into three main systems based on sediment provenance—bedrock, alluvial fan (fan delta), and braided river systems—each exhibiting unique compositional and structural attributes. Terrain gradient around the lake significantly affects beach bar formation, with areas having a gradient less than 0.7° being particularly favorable. This research advances our understanding of lacustrine beach bar dynamics, offering insights into their potential as indicators of past environmental conditions and their implications for hydrocarbon exploration. The comprehensive analysis of controlling factors provides a foundation for predicting beach bar distribution and contributes to the broader field of sedimentary geology by integrating multi-disciplinary approaches to study lacustrine sedimentary processes.

Lake-level responses to climate change in an inland basin in the Japanese Islands during the last 16 kyr

During the last deglaciation and middle Holocene, rapid climatic changes occurred repeatedly. Previous research has primarily focused on investigating these periods in East Asia's coastal and inland regions of the Eurasian continent. In contrast, a limited number of studies have reported on climate change and its environmental impacts in island areas near the Pacific Ocean. This study aims to reconstruct paleosol drainage conditions and lake water level fluctuations in the Suwa Basin, an inland basin in central Japan, after the last deglaciation. We utilize the identification of paleosols and the geochemistry of lacustrine sediments to discuss climate change and its impacts on terrestrial environments in the East Asian coastal region. During the Last Glacial Maximum, the basin experienced a lowstand period; meandering fluvial systems led to the development of dry and well-drained paleosols. The lacustrine environment expanded between ca. 16 cal kyr BP and 5 cal kyr BP during a transgressive period. Short-term lake-level fluctuations were reconstructed by examining repeated paleosol development and changes in the bulk SiO2 content originating from biogenic silica in lacustrine sediments. Our data suggest that the lake's water level fell at ca. 12 cal kyr BP, 8 cal kyr BP, and 7 cal kyr BP. After 5 cal kyr BP, thin paleosols repeatedly formed during short exposure times due to the rapid sedimentation rate in the delta system, which corresponds to the highstand period. Short-term fluctuations between 16 kyr BP and 5 kyr BP, in the lake water level in the inland basin of the Japanese Islands was influenced by drying and cooling trends in the East Asian coastal region, as well as declines in sea surface temperatures in the western tropical Pacific Ocean. These fluctuations roughly synchronize with the Younger Dryas stadial and an 8.2 ka cooling event. Changes in precipitation, which responded to fluctuations in the East Asian summer monsoon intensity and tropical depressions, likely regulated the lake water level. These findings imply the predominant influence of paleoclimate fluctuations over thousands of years on the hydrological regime of lake systems across the island area of the East Asia.

The Lake Effect: Lake Michigan, Landscape Evolution, and the Archaeological Record of the Chicago Region

Abstract Lake Michigan continues to have a major impact on the environment in the Chicago region, and changes in lake levels were a major driver of landscape evolution throughout the late Pleistocene and Holocene. Fluctuating lake levels reduced or increased the extent and character of terrestrial resources. The landscape has also been altered by erosional and aggradational processes from near-shore currents and wave action. Interpretation of archaeological site and settlement patterns in this region requires an understanding of the factors that have shaped and continue to shape this landscape. In the PaleoIndigenous and Archaic periods, foraging groups adapted to rapidly changing vegetation patterns and episodes of lake transgression and recession that opened or closed new habitats. In the Woodland and Upper Mississippian periods, lake levels stabilized, but the landscape continued to evolve, with erosion and deposition of sediments along Lake Michigan shorelines. Evidence for lake-level fluctuations over the last 12,000 years is available from a variety of data sets, including those for deep lacustrine sediments, ostracods, abandoned shorelines, and sand dunes. By synthesizing these data and utilizing GIS to reconstruct past lakeshores, we seek to better understand how people interacted with and adjusted to this dynamic landscape.

Thinning and dynamics of the glacier terminus at the Pasterze Glacier (Austria), 2016–2021

As a result of global warming, glaciers worldwide recede and lose mass. Glacier ablation is influenced by surface characteristics, in particular the existence of debris cover. The evolution of glaciers may also be influenced by the existence of proglacial lakes, which are worldwide increasing in number and size. We examine the recent changes of the terminus of Pasterze Glacier by discussing the thinning and dynamics of the glacier terminus along with the changes of the glacial-proglacial transition zone between September 2016 and September 2021. By considering land cover in the interpretation, we find that glacier surface characteristics show different rates of elevation changes and surface movement. We mainly use orthophotos and digital elevation models (DEMs) resulting from airborne surveys of 12 different acquisition dates, but also draw on ablation stake measurements, lake water level data, water temperature data, as well as thermal infrared (TIR) imagery. While debris-covered ice lowered typically −5.0 m a−1 ± 4.6 m a−1 (mean ± standard deviation), debris-free ice was affected by ablation in the range of −7.0 m a−1 ± 2.7 m a−1, thus demonstrating that melt rates in similar elevations are related to surface characteristics. The elevation change rates were, in most cases, in a similar range throughout the observed periods of time. The horizontal displacement close to glacier-marginal crevasses amounted to up to ∼8 m a−1, but was mostly in the range of ∼1–4 m a−1. Considering both horizontal displacement and elevation changes, we find that clean and dirty ice surfaces show larger thickness losses and are moving faster compared to debris-covered glacier surfaces. Diurnal and seasonal fluctuations of lake water levels in the range of decimeters and lake water temperatures mostly clearly exceeding 0 °C are indicative of the potential influence of the proglacial lake on the glacier terminus. Given the decelerating and decaying behavior of the Pasterze Glacier in recent decades, we interpret the change rates of surface lowering and horizontal displacement 2016–2021 to be influenced by other factors such as the recently formed proglacial lake. This is also supported by direct ablation measurements that mostly show lesser ice melt differences compared to DEM-based surface elevation changes, suggesting that other factors such as thermally-induced melting contributed to an increased elevation difference.