Sediment Accumulation Research Articles

LATE GLACIAL AND HOLOCENE EROSIONAL DISSECTION AND FILL IN THE TEMPORAL (EPHEMERAL) STREAM VALLEY ON THE RIGHT BANK OF THE SELENGA RIVER

The structure, composition and cut and fill sequence of the Late Glacial and Holocene erosional landforms in the Kuitunka River basin on the right bank of the Selenga River were studied based on a detailed analysis and radiocarbon dating of the soil-sedimentary sequence in the Studenyi Klyuch 2 and Kovalev Pad’ sections. A correlation was carried out between seven sections in the intermittent stream valleys in the Kuitunka River basin. There are three episodes of the Late Glacial and Holocene cutting dated back to ~18–17, ~14.7–14.3, and 0.25–0 cal. kyr BP (ka BP). There are distinguished the periods of colluvial, colluvial-deluvial and aeolian-deluvial sediment deposition in the intermittent stream valleys (17.0–14.7 ka BP) and predominantly aeolian-deluvial loess-like sediment accumulation involving pedogenetic stages (14.30–0.25 ka BP). The climatic warming and humidification led to a decrease in sedimentation rate, prevalence of loessification processes in formation of loess-like deposits, and formation of organic–accumulative soil horizons of different thicknesses. The Late Glacial warming, comparable to the Bølling – Allerød Interstadial (14.3–12.9 ka BP) and the Holocene (11.7–0 ka BP), is characterized by a dynamic change in the stages of loess-like deposit accumulation and pedogenesis. The Younger Dryas cooling (12.9–11.7 ka BP) is associated with the activation of aeolian and cryogenic processes and a short phase of pedogenesis. It was revealed that the most frequent changes in sedimentary phases and soil formation occurred during the Late Glacial Interstadial and the Early (11.7–8.2 ka BP) Holocene. The Middle Holocene (8.2–4.2 ka BP) is characterized by a decrease in the rate of accumulation of intermittent-stream valley loess-like bottom deposits and a long-term (several ka) active pedogenetic process. The cross-sections of the Late Holocene (last 4.2 ka BP) draws and valley-bottom gullies exhibit the stages of pedogenesis (4.2–1.0 ka BP), activation of erosion–accumulation processes (1.00–0.25 ka), gullying, accelerated erosion, and accumulation (last 0.25 ka BP).

Sedimentary Model and Geological Control of the Ganquan Platform in the Xisha Sea Area, South China Sea

The Ganquan Platform, located in the South China Sea, exhibits distinctive topographic and geomorphological features shaped by complex geological processes. Utilizing high-resolution multibeam bathymetry and multi-channel seismic data, this study provides a comprehensive investigation into the sedimentary evolution and stratigraphic framework of the platform. Morphologically, the platform is identified as an elongated seamount, with water depths ranging from 530 m to 800 m and a maximum elevation of 538.115 m. Seismic facies analysis reveals seven distinct facies, reflecting a dynamic and intricate history of carbonate deposition. The stratigraphic framework delineates three primary evolutionary stages: the growth phase (Early Miocene), characterized by the initial accumulation of carbonate sediments; the flourishing phase (Middle Miocene), marked by extensive deposition and platform expansion; and the submergence phase (Late Miocene), defined by progressive submersion and erosion of carbonate features. This evolutionary trajectory was driven by key factors such as terrigenous clastic input, tectonic activity, sea-level fluctuations, and paleoenvironmental dynamics. The findings contribute to a deeper understanding of the Ganquan Platform’s geological history and its role in the broader context of submarine geology in the Xisha region.

Delayed environmental pollution caused by transient landscape storage - An example from the Lesser Antilles.

The strong pest pressure on intensive banana cultivation in the French West Indies led to the intensive use of chlordecone (an organochlorine insecticide) between 1972 and 1993. Due to its high toxicity for the population and the environment, many studies were conducted on the transfer of chlordecone over the last 20 years. However, most studies focused on the dissolved fraction of chlordecone, while the particle-bound fraction was understudied. Therefore, this study reconstructs pluri-decadal erosion rates (i.e. 1980-2023) and associated chlordecone particle-bound transfers from soil and sediment cores sampled in a cultivated headwater catchment (Saint-Esprit, Martinique). Based on sediment accumulation analysis in an agricultural reservoir, high erosion rates (i.e. 10 t ha-1 yr-1) were found in the investigated catchment during the study period, with values exceeding the estimated tolerable soil loss rate in tropical context (i.e. 2.2 t ha-1 yr-1). Based on the analysis of soil cores sampled along a banana plantation hillslope, this study highlights the formation of colluvial deposits with high levels of chlordecone contamination. When these areas are affected by erosion processes, this leads to massive remobilization of particle-bound chlordecone to water bodies. Indeed, in sediment sampled in the downstream reservoir, we observed a drastic increase in these transfers since 2006, synchronous with changes in agricultural practices. This study therefore highlighted the occurrence of legacy contamination at toeslope positions, which was estimated to potentially persist for 4000 to 11,000 years. Such a residence time highlights the need to implement changes in land management to effectively reduce agricultural soils erosion, particularly in areas identified as "temporary deposition zones" for chlordecone contamination, in order to protect downstream water bodies from chlordecone transfer. To achieve this, agricultural practices that may increase soil erosion, such as herbicide application or intensive ploughing, should be minimized. Overall, this study improved our understanding of erosion and associated chlordecone transfers in tropical environments.

Age and sources of the kodar group rocks of the udokan complex (Aldan shield): results of geochemical, U–Th–Pb (LA-ICP-MS) geochronological and Nd–Hf isotopic studies

The paper presents the results of geochemical and Nd whole rock isotopic studies, as well as U–Th–Pb (LA-ICP-MS) geochronological and Hf isotope studies of detrital zircon from metaterrigenous rocks of the Kodar Group of the Udokan Complex, Aldan Shield. It has been established that the rocks of the Kodar Group have an age of 1.99–1.91 Ga, and the rocks of the Chinei and Kemen groups of the Udokan Complex are in the range of 1.90–1.87 Ga. This allows us to raise the question of identifying the Kodar Group as an independent stratigraphic unit. Archean igneous and metamorphic rocks of the Chara-Olekma Geoblock and, probably, the Kalar and Kurulta blocks of the Stanovoy suture zone, as well as Paleoproterozoic (2.04–1.99, 2.08, 2.20 and 2.30 Ga) complexes of active continental margins or ensialic island arcs in the western–northwestern and southern (in modern coordinates) framing of the Chara-Olekma Geoblock, not identified in the region on the modern erosion level, were the sources of terrigenous rocks of the Kodar Group. Erosion of rocks of the igneous arcs and the continental slope led to the accumulation of sediments of the Kodar Group in the retro-arc foreland basin setting, and the subsequent collapse of the orogen and the formation of an intracontinental extension basin led to the accumulation of terrigenous rocks of the Chinei and Kemen groups. Obtained data indicate widespread previously unidentified Paleoproterozoic continental crust formation at about 2.04–1.97 Ga in the western part of the Aldan Shield.

Holocene evolution of the buried tidal sand body in the North Jiangsu Plain of China revealed by luminescence dating

In the northern Jiangsu coastal zone of China, the buried tidal sand body (BTSB) is suggested to share a similar origin with the offshore radial sand ridge system in the southwestern Yellow Sea. However, its chronological framework remains inadequately understood. This study conducted optically stimulated luminescence (OSL) dating of both silt- and sand-sized quartz on core LDC from the southwestern end of the BTSB. Together with data from the previously studied core XYK closer to the current coastline, this study aims to clarify the chronology of the BTSB and refine its evolution history. The results indicate that in both cores, sand-sized quartz provides more reliable age estimates than silt-sized quartz for the sandy sediment layers. Additionally, the discrepancy between ages derived from the single-grain central age model and the minimum age model is smaller within the top 11 m of the core, which was deposited over the last 0.9 ka. This period corresponds well with the southern migration of the Yellow River and its sediment discharge into the Yellow Sea from 1128 to 1855 CE. It suggests that distinct sediment sources from the Yellow and Yangtze Rivers may account for the observed differences in OSL characteristics. The OSL ages reveal significant temporal variations in sedimentation rates during the Holocene, with the most rapid deposition occurring between 1.2–0.4 ka and 10–8 ka in core LDC, and between 2–1 ka in core XYK. Together with dating results from the central part of the BTSB, it reveals complex spatiotemporal variations in sediment accumulation and emphasizes the need for detailed sediment sampling and dating to fully elucidate the evolutionary history of the coastal plain.

Spatiotemporal controls on organic matter sourcing to minerogenic salt marshes

AbstractSalt marshes are important carbon sinks; however, identification of the drivers of carbon burial rates is challenging because estuaries sit at terrestrial and marine interfaces. Here, we address the questions: what are the sources of organic matter sequestered in minerogenic salt marshes, and how do sources change through time? We characterized down‐core sediment biogeochemistry (C : N, δ13C, δ15N) for the last century in seven Oregon USA high marshes and used a mixing model to elucidate differences in organic matter sources across estuaries and through time. Autochthonous biomass production consistently accounted for only half of overall organic matter accumulation, and the remainder was allochthonous, originating from a combination of estuarine and terrestrial sources. Salt marshes with high sediment loads buried more terrestrial organic matter, whereas those with low loads and substantial subtidal habitat buried more estuarine‐derived organic matter. When assessed through depth/time, stable isotope trends indicated that decomposition is not the primary control. Instead, organic matter became increasingly more terrestrial in recent decades, especially in salt marshes with low fluvial loads. We hypothesize that salt marshes with lower loads took longer to regain lost elevation following coseismic subsidence of the 1700 ce Cascadia earthquake. This result magnifies the role of river floods in sediment and carbon accumulation on the marsh surface. Ultimately, the highest carbon burial rates coincided with highest fractions of terrestrially sourced organic matter, though spatiotemporal complexities obscured any potentially significant trends. While the term “blue” typically excludes terrestrial carbon, minerogenic salt marshes still perform the important ecosystem function of burying organic matter.

Polycyclic aromatic hydrocarbons in surface sediments of the western Bay of Bengal: Distribution, sources, and ecological risk assessment

This study investigated the distribution, sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the Western Bay of Bengal (WBoB). Coastal, shelf and slope sediments from the WBoB, collected from different research cruises, were analysed for 16 priority PAH pollutants. Total PAHs (TPAHs) were in the range of 1.87–918.79 ng/g and exhibited a significant association with organic matter and silt content with a predominance of high molecular weight (HMW) PAHs congeners. The preferential degradation of the labile low-molecular-weight (LMW) PAHs resulted in the sedimentary accumulation of HMW congeners. A comparison with reported values from other oceanic areas revealed a relatively low concentration of PAHs in WBoB. The isomeric ratios of PAHs could suggest a pyrogenic or petrogenic (crude oil) origin of PAHs. Principal component analysis indicated the dominance of HMW PAHs (petrogenic or combustion) over the LMW fraction. Based on sediment quality guidelines, four congeners [Pyrene (Py), Benzo[a]anthracene (BaA), Chrysene (Ch), and Dibenzo[a,h]anthracene (DbA)] exceeded the threshold effect levels, indicating an adverse impact of these PAHs on the benthic fauna occasionally. The corresponding risk quotients further indicated a moderate risk caused by Py, BaA, and Benzo[b]fluoranthene (BbF) to the biota. This study underscores the importance of proactive management and mitigation strategies to safeguard these vital oceanic ecosystems from the adverse effects of PAHs and other hazardous materials.

Understanding sediment and carbon accumulation in macrotidal minerogenic saltmarshes for climate resilience

Coastal saltmarshes play an essential role in providing services such as sediment and carbon storage, coastal protection and support for biodiversity. Despite their importance, understanding the factors controlling sediment and carbon accumulation in these minerogenic saltmarshes remains challenging due to their diversity and site-specific characteristics. Understanding the respective role of these drivers is essential for effective coastal management, particularly for mitigating the impacts of climate change. This study evaluates the control of forcing factors on the lateral and vertical morphological evolution and carbon burial rates of three minerogenic saltmarshes located on the French Atlantic coast (Pertuis Charentais region). By focusing on these sites, the study isolates specific factors such as wind and wave exposure, inundation frequency, and sediment availability, while minimizing confounding influences like climate and tidal range. Results reveal significant lateral expansion of saltmarsh boundaries towards the sea across all sites, with the highest rates of progradation observed in the protected areas influenced by geomorphological features such as sand spits and sheltered bay heads. Sediment and mass accumulation rates (SAR; MAR), derived from 210Pb and 137Cs profiles of sediment cores (n = 14), range from 0.48 to 2.22 cm yr−1, among the highest reported globally, with notable variability within and between sites. Inundation frequency and accommodation space explain SAR variability within sites, while sediment availability predominantly determines spatial differences in vertical accumulation rates between sites. Organic carbon burial rates range from 75 to 345 gC m−2 yr−1, and show a strong correlation with SAR (r = 0.9, p < 0.001, n = 13) but no dependence on carbon content or density (r = 0.2, p > 0.05, n = 13). This highlights the role of sediment input in the accumulation and sequestration of carbon by minerogenic saltmarshes. Furthermore, isotopic analysis indicates a marine source dominance in organic carbon sediment. This research provides insights into how different environmental conditions affect saltmarsh morphological evolution and carbon sequestration rates, informing targeted coastal management strategies focused on enhancing ecosystem resilience and climate resilience.

Comparison of multitemporal multifrequency multibeam echosounder norbit iwbms: depth and sedimentation rate analysis of selorejo reservoir 2022-2023

Abstract Selorejo Reservoir is a reservoir constructed and located in Pandansari Village, Ngantang District, Malang Regency, East Java. The Indonesian Government built this reservoir to accommodate the water flow from several rivers, including the Konto River, Kletak Lahar, Kwayangan River, and several other small rivers. The biggest challenge for a reservoir, where the primary clean water source comes directly from rivers, is siltation caused by sediment accumulation at the bottom of the water body. Therefore, severe and continuous control in the reservoir area is necessary to prevent damage and overflow and ensure the community’s safety by engaging in activities around the Selorejo Reservoir. Bathymetric surveys are essential in obtaining information related to marine fields and precise depth values with spatial references. When using a multibeam echosounder, surveyors must consider several aspects regarding the specifications of the equipment before data acquisition, one of which is the frequency used. Different frequencies result in different penetration abilities and data quality. This study aims to estimate the sedimentation rate in the Selorejo Reservoir using multitemporal data and investigate the effect of using multifrequency on the depth measurement results obtained. The results of this study indicate that the higher the frequency used, the shallower the depth value obtained. Higher frequencies provide better representation in object detection capabilities. At the same time, the sedimentation rate was relatively high, from 3.2 to 5.3 centimetres per month.

Identifying drivers of global spatial variability in organic carbon sequestration in tidal marsh sediments

Tidal marshes are among the most efficient ecosystems on Earth for carbon sequestration with a globally averaged rate of sediment organic carbon accumulation of 210 g C m−2 y−1, but with large spatial variations between marsh sites from 20 to 1700 g C m−2 y−1 worldwide. Previous studies identified certain environmental drivers of spatial variability of carbon sequestration in tidal marshes, but have considered so far a rather limited number of environmental variables. In this study, we started from a large dataset that includes 477 tidal marsh sites scattered worldwide and investigated the influence of 12 different environmental variables on sediment organic carbon content, density and accumulation rates using a Random Forest regression algorithm. We find that variability in organic carbon content is mostly explained by variables determining the tidal inundation regime, such as tidal range and tidal pattern, where high tidal range corresponds with low values of organic carbon content, potentially due to increased soil aeration and decomposition. Organic carbon density is found to increase with increasing marsh vegetation productivity and vegetation cover, which may promote plant carbon inputs into the sediment bed and trapping of sediments supplied by the tides. Further, organic carbon accumulation rate is mostly controlled by sea level rise, which has a positive effect on sediment accretion rate and thus on organic carbon accumulation rate. Our findings highlight that it is not one or a few environmental variables, but the interaction between different variables that affects the spatial variability of organic carbon sequestration in tidal marsh sediments.

Determining the Location of Coastal Protection Structures in Sealing with Sedimentation Problems using Hydrodynamic Modeling

Abstract Lamong Bay is a water area located between the coasts of Gresik and Surabaya. The geographical condition, which is the estuary of several rivers, makes this bay area face sedimentation problems. The process of sedimentation is caused by the movement of sediment, which is divided into 3 types: Bed Load, Suspended Load, and Wash Load. The relatively gentle slope of the topography also affects the accumulation of sediment. One very effective solution in dealing with sedimentation is the existence of coastal protection structures. The existence of coastal structures aims to resist the movement of sediments influenced by ocean currents. Thus, this study aims to determine the type and location of coastal protection structures in reducing the rate of sediment transport in the study area. The method used is numerical modeling using Delft3D software. Modeling validation is done by finding the deviation value of the modeled tides with tides from the BIG tide station. The validation calculation method uses statistical calculations with the Root Mean Square Error (RMSE) method, Mean Absolute Percentage Error (MAPE), and R correlation to find the relationship between modeling and measurement. Sediment types in the Lamong Bay area consist of silt, clay, and sand, with the largest composition in the silt type at 84%. Alternative 1, where the structure is placed in the south of the bay area, shows a cumulative sedimentation value of 0.130 m, while alternative 2 in the north shows 0.180 m. Hence, alternative 1 is more effective. This study contributes to SDG 9 by promoting resilient infrastructure to manage sedimentation issues effectively.

Tectonics and climate controlled sedimentary provenance in the teesta basin since mid-holocene

Erosion of the Himalaya Mountain and subsequent deposition of sediments in the flood plains, and distal fans are primarily regulated by tectonics, climates, lithology, and relief of the region. These eroded sediments preserve their chemical and isotopic compositions in their depositional archive, which can be used to trace the erosion processes, assess the relative role of controlling factors and their spatio-temporal variations. The present study have analysed the 87Sr/86Sr and ԐNd of in silicate phase of sediment recovered from a ~ 40 m long sedimentary core representing ~8 ky of sediment accumulation in the Teesta River mega fan. The lithostratigraphy of the core indicates rapid aggradational nature of the Teesta mega fan. The 87Sr/86Sr and ԐNd display large variability with depth, which ranges from 0.75700 to 0.89294 and − 15.1 to −25.0, respectively. The observed 87Sr/86Sr and ԐNd values in the core sediments have been interpreted in terms of differential sediment contribution from the Higher and the Lesser Himalayan lithology. The 87Sr/86Sr and ԐNd isotope profiles and estimated fractional sediment contributions identify the Lesser Himalaya as the major sediment contributor to the Teesta basin since the mid-Holocene, unlike the other Himalayan River basins, dominated by sediments from the Higher Himalaya after the Last Glacial Maximum. The rapid exhumation and erosion of the tectonically active Rangeet window with the focused precipitation and presence of rock types vulnerable to weathering in the Lesser Himalaya of the basin appear to be the major factors resulting the sedimentary budget of the Teesta River basin over at least last 8 ky. Our assessment suggests that tectonic activity and climate have a competitive effect for the observed sedimentary budget, with an additional role of lithology. The study infers a major control of active tectonics, precipitation, and lithology on the sedimentary budget of the Himalayan River basins.

The missing woodland story: Implications of 1700 years of stand‐scale change on ‘naturalness’ and managing remnant broadleaved woodlands

Abstract Longer‐term perspectives—equivalent to the lifespans of long‐lived trees—are required to fully inform perceptions of ‘naturalness’ used in woodland conservation and management. Stand‐scale dynamics of an old growth temperate woodland are reconstructed using palaeoecological data. The study site is Cambusurich Wood, Scotland, a woodland designated for conservation due to its ‘naturalness’. High temporal resolution palaeoecological records (pollen, plant macrofossils, non‐pollen palynomorphs and charcoal analyses) are used to explore long‐term human‐woodland interactions and the drivers of stand‐scale woodland dynamics. The results demonstrate stand‐scale woodland responses to climatic changes and human‐woodland interactions (increasingly) since 220 cal. BP (1730 CE). Periods of intense herbivore grazing and trampling altered the local vegetation composition and sediment accumulation. Greater vegetation diversity is associated with woodland disturbance through fire and moderate grazing. Subsequent cessation of localised burning and continued (long‐term) grazing have had legacy effects on woodland composition and diversity. Synthesis and applications: The current woodland is identified as being compositionally and structurally distinct from past woodland conditions, and its perceived ‘naturalness’ can be considered a ‘shifted baseline’, highlighting the importance of longer‐term perspectives to woodland management. Human‐woodland interactions are important in shaping modern woodlands and should not be overlooked in future management strategies as human‐induced disturbance can promote woodland diversity, resilience and valuable ecosystem characteristics. Read the free Plain Language Summary for this article on the Journal blog.

Assessing the geochemical correlation between petroleum source rocks in the Brazilian Equatorial margin basins and global oceanic anoxic events

This research aims to investigate the correlation between the Cretaceous Oceanic Anoxic Events (OAEs) and the source rocks of the Brazilian Equatorial Margin (BEM) basins. These source rocks, particularly from the Cenomanian-Turonian interval, are known to contain high levels of Total Organic Carbon (TOC) and exhibit significant hydrocarbon potential. The principal focus is on how global anoxic events, such as OAE-1b, OAE-1d, and OAE-2, influenced the depositional environments and organic matter types across the BEM basins, which include Foz do Amazonas, Pará-Maranhão, Barreirinhas, Ceará, and Potiguar. Key results indicate a strong correlation between periods of anoxia and the accumulation of organic-rich sediments in these basins. The Foz do Amazonas Basin features predominantly terrestrial-derived kerogen (Type III), while the Ceará and Potiguar basins show marine-derived kerogen (Type I and II), aligning with global productivity patterns during anoxic events. These variations in kerogen type reflect differences in depositional environments influenced by sea-level changes and nutrient influx. The research concludes that the OAEs significantly impacted organic matter preservation and hydrocarbon generation in the BEM basins. The study's findings contribute to the broader understanding of how Cretaceous OAEs shaped the geochemical and sedimentary processes in equatorial Atlantic margins, highlighting the potential for further oil and gas exploration in these regions.

Lake Trafford Nutrients Budget and Influxes After Organic Sediment Dredging (South Florida, USA)

Lake Trafford, a 600-ha subtropical lake in southwestern Florida, has suffered from over 50 years of cultural eutrophication, resulting in the invasion of Hydrilla verticillata and organic sediment accumulation due to herbicide treatments. This study aimed to assess the effects of dredging on nutrient dynamics. A pre-dredging nutrient budget, developed using land use models and climatic data, estimated nutrient loads of 190 kg d−1 for total nitrogen (TN) and 18.6 kg d−1 for total phosphorus (TP), with total maximum daily loads (TMDLs) of 70.4 kg d−1 for TN and 4.15 kg d−1 for TP. Post-dredging analysis, using detailed spatiotemporal data, showed higher nutrient loads of 274.3 kg d−1 for TN and 24.2 kg d−1 for TP. While dredging reduced legacy nutrient accumulation, it led to increased nutrient influx from groundwater, caused by the exposure of organic sediment, as evidenced by increased lake water electrical conductivity. These findings demonstrate the importance of conducting thorough pre-dredging assessments to mitigate unintended consequences, offering practical insights for managing nutrient loads and improving restoration strategies in eutrophic lakes.

Geology aspects and formation of the erosional structure of Upper Miocene deposits of the Western Cicaucasus

The results of regional studies of the Early Miocene deposits of the Western Ciscaucasia, carried out on the basis of seismic stratigraphic analysis, are presented. The spatial pattern of sediment accumulation is analyzed and the paleogeographic conditions during the regressive stages of the Late Miocene in the Western Ciscaucasia are clarified. Erosion incisions of several levels were identified, which developed during the fall of the erosion base level during major regressions in the studied time interval. By spatial correlation of paleochannels based on a selected series of intersecting seismic profiles, the buried river valleys of the Paleo-Don and Paleo-Donts were reconstructed and constructed at the Sarmatian‒Meotis boundaries and within the Late Meotis‒Late Pontian interval.

Bioturbation increases time averaging despite promoting shell disintegration: a test using anthropogenic gradients in sediment accumulation and burrowing on the southern California shelf

Bioturbation increases time averaging despite promoting shell disintegration: a test using anthropogenic gradients in sediment accumulation and burrowing on the southern California shelf

Rare earth element patterns in sediments from the Great Lakes basin

This study presents a comprehensive analysis of rare earth element (REE) concentrations in >100 sediment samples from Lakes Erie and Huron, two of the North American Great Lakes. Significant intra- and inter-lake variability in REE concentrations is observed for both lakes Erie and Huron (<10 μg/g < versus <6 mg/g ƩREE, respectively). Light (L) REE were enriched over heavy (H) REE in surface sediment samples across both lakes, particularly in the North Channel of Lake Huron. Sediment cores from both lakes contained REE concentrations that are equally variable over time and correlated with major elements and other trace metals, reflective of the strong control of sediment accumulation rates on REE concentrations. Sequential extractions show that REE are predominantly associated with the residual (silicate) fraction (>50%) and likely originated from geogenic sources (basin weathering). However, considerable REE fractions (up to 16%) were also associated with oxide, phosphate minerals and organic/reducible material, particularly for the LREE. We attribute this apportionment and LREE enrichment to aqueous complexation and export from the water column. Finally, REE normalization and pattern-fitting reveal positive Ce anomalies (up to 16.2) in specific locations that could be indicative of hypolimnic redox gradients, whereas minor Gd and Eu anomalies (0.9 for Eu, and 1.02 for Gd, on average) likely relate to the parent rock signature. Our findings contribute valuable baseline data and insights into the complex interplay of geological, hydrodynamic, and environmental factors influencing REE distribution patterns in these lake sediments.

The Regional Scale of Landscape Planning: the Possibilities for Measuring the Effectiveness of Nature-Based Solutions

Aim: The aim of this study is to investigate the measurement of landscape integrity based on ecological support processes in the Federal District, with the aim of defining a multi-scalar and multi-functional Regional Green Infrastructure Network (IVR) based on Nature-Based Solutions (NBS). Theoretical Framework: This topic presents the main concepts and theories that underpin the research. Landscape Ecology, Restoration Ecology, Green Infrastructure and Geodesign stand out, providing a solid basis for understanding the research context. Method: The methodology adopted for this research comprises the analysis of ecological support processes in the landscape, using the multispectral “CO2flux” index, related to the photosynthetic efficiency of vegetation and a proxy for energy, carbon and biomass inputs, which, together with the “Topographic Wetness Index”, related to the flow and accumulation of water and sediment in the landscape, provided the basis for the elaboration of a Geodesign process. Data was collected using multispectral satellite scenes - “Landsat 8”, collected during the dry season. Results and Discussion: The results obtained revealed the design of a mosaic of “hotspots”, corridors and patches that consolidates and intensifies carbon flows in the Federal District's landscape, with positive impacts on territorial resilience. In the discussion section, these results are contextualized in the light of the theoretical framework, highlighting the implications and relationships identified. Possible discrepancies and limitations of the study are also considered in this section. Research Implications: The practical and theoretical implications of this research are discussed, providing “insights” into how the results can be applied, or how to influence practices in the field of landscape planning. These implications can cover the design of Nature-Based Solutions at a regional scale, climate mitigation and adaptation actions for territories, and people's access to ecosystem services. Originality/Value: This study contributes to the literature by proposing the design of a regional network of green infrastructures based on the analysis of the flow of ecological support processes in the landscape, considering different demands and goals for environmental recovery. The relevance and value of this research is evidenced by the possibility of planning and designing mosaics in the landscape based on the identification of networks with greater potential for the provision of ecosystem services and, consequently, for the adaptation and mitigation of territories to climate impacts and those resulting from human occupation.

RECONSTRUCTION OF THE SUBSIDENCE DYNAMICS AND PALAEOTEMPERATURE REGIME OF THE NORTHERN MARGIN OF THE SIBERIAN PLATFORM

The formation mechanisms of sedimentary basins are considered as a response of deep processes in the mantle, therefore they carry important information about the geodynamics and thermal regime of the lithosphere. For different sectors of the northern margin of the Siberian Platform, the dynamics of sedimentation and subsidence was reconstructed. The analysis of subsidence curves shows that during the Late Paleozoic the sedimentary infill formed in the foreland basin environment. In the Late Permian–Early Triassic time, in the central and western sectors, the subsidence was accelerating due to the development of a thick trap complex; after the Permian and Triassic boundary the subsidence slowed down. During the period of trap magmatism, an anomalously high subsidence rate up to 4.8 km/Ma in the central and up to 0.5–1.1 km/Ma in the eastern and western parts was reconstructed. The high rate and short duration of accumulation of volcanogenic sediments can be explained by an episode of short-term extension under the influence of a plume, followed by a long period of thermal subsidence. Numerical modelling of the temperature regime near mafic intrusive bodies was carried out, which showed that when determining the paleoheat flow, the influence of trap intrusions can be traced up to 400–500 m from the contacts. Estimates of the paleoheat flow for the Permian–Triassic stage of tectonic evolution of the eastern sector were obtained. It was calibrated using the PetroMod software package, based on laboratory measurements of modern values of vitrinite reflectance for rock samples from wells, modern temperature and heat flow in the sedimentary cover. It was determined that trap magmatism occurred at temperatures increased to 100 mW/m2, while the mantle component of the heat flow reached 38–72 mW/m2; it is several times higher as compared to modern one. The obtained paleoheat flow estimates for the Late Permian–Early Triassic stage appear to correspond to anomalously high values of modern continental rifts.