Sedimentary Material Research Articles

Mapping inland water bathymetry with Ground Penetrating Radar (GPR) on board Unmanned Aerial Systems (UASs)

Bathymetry of inland water bodies is essential for river maintenance and flood risk management. Traditionally, in shallow water bodies, bathymetry is retrieved by operators wading through the water body with Real Time Kinematic (RTK) Global Navigation Satellite System (GNSS), whilst in deeper waters, it is retrieved with sonar instruments on manned or unmanned boats. In the past, researchers have documented the use of Ground Penetrating Radar (GPR) on boats (i.e. water-coupled GPR) for monitoring the bathymetry of frozen and non-frozen water bodies. Furthermore, GPR has been used on helicopters for monitoring ice and snow thickness. However, deployment of GPR on board Unmanned Aerial Systems (UASs) in non-frozen inland water bodies with electric conductivity higher than 100 μS/cm (as is common in most inland waterbodies in non-polar regions) is unexplored. In this paper, we document the possibility to use drone-borne and water-coupled GPR in several cross-sections located in three different waterbodies (1 lake and 2 rivers) in Denmark. These waterbodies had different bed sediment materials and vegetation conditions, an electric conductivity varying from 200 to 340 μS/cm and depths up to 2.5 m. Drone-borne GPR showed accuracy similar to water-coupled GPR when compared to RTK GNSS ground-truth measurements, with a Mean Absolute Error (MAE) of approx. 8 cm. The only limitations of drone-borne GPR were i) more restrictive minimum depth requirement (typically 0.8–1.1 m for drone-borne GPR, while 0.3–0.4 m for water-coupled GPR) ii) requirement to fly the GPR antenna at altitudes of approx. 0.5 m above the water surface to avoid high spreading losses and strong surface clutter events hiding the signal. Finally, GPR measurements were benchmarked against traditional sonar measurements, showing that GPR measurements significantly outperform sonar measurements in waterbodies with medium or high density of aquatic vegetation.

Application of organic petrography as a forensic tool in environmental studies to investigate the source of coal pollution on beaches in Gijón (Northern Spain)

Coal is one of the oldest and most widespread pollutants of natural environments such as marine coastal areas. The sources of this pollution are varied and mainly anthropogenic, one of which is handling coal in marine coal terminals and in bulk seaports. In coastal environments, there is also accidental coal pollution caused by accidents such as shipwrecks or sinking of bulk carriers and barges operating in port areas. One case of coal pollution is the beaches in Gijón on the Cantabrian coast in the north of Spain, which are intermittently covered to varying degrees by carbonaceous materials. To the north of Gijón there is a bulk seaport, El Musel, the largest bulk seaport in Spain where millions of tons of coal and other carbonaceous materials are handled annually. In January 1986 the Castillo de Salas bulk carrier sank with 100,000 tons of coal off the beaches of Gijón. For >34 years the true origin of the coal staining the beaches has been the subject of controversy at all levels of society. The aim of this study was to determine the main source of coal pollutants on the beaches. To that end, organic petrography was used to determine the mixtures of coal and other carbonaceous materials in sediments. The results indicate that the El Musel seaport is quantitatively the main source of coal pollution on the beaches and that coal from the sunken vessel reaches the beaches only during significant storms, heavy waves, and strong tides, which are common on the Cantabrian coast. Organic petrography emerged as a powerful forensic tool that can be applied to environmental investigations to determine the source of coal pollution, which is especially important in controversial cases.

Mineralization of autochthonous particulate organic carbon is a fast channel of organic matter turnover in Germany's largest drinking water reservoir

Abstract. Turnover of organic matter (OM) is an essential ecological function in inland water bodies and relevant for water quality. This is especially important for the potential of dissolved organic carbon (DOC) removal as well as for emissions of CO2. In this study, we investigated various phases of OM including DOC, autochthonous particulate organic carbon (auto-POC), allochthonous particulate organic carbon (allo-POC), and sedimentary matter (SED) in a temperate drinking water reservoir (Rappbode Reservoir, Germany) by means of dissolved inorganic carbon (DIC) concentrations and carbon stable isotope ratios. In order to best outline carbon turnover, we focused on the metalimnion and the hypolimnion of the reservoir, where respiration is expected to be dominant and hardly disturbed by atmospheric exchange or photosynthesis. DIC concentrations ranged between 0.30 and 0.53 mmol L−1, while δ13CDIC values ranged between −15.1 ‰ and −7.2 ‰ versus the VPDB (Vienna PeeDee Belemnite) standard. Values of δ13CDOC and δ13Cauto-POC ranged between −28.8 ‰ and −27.6 ‰ and between −35.2 ‰ and −26.8 ‰, respectively. Isotope compositions of sedimentary material and allochthonous POC were inferred from the literature and from measurements from previous studies with δ13CSED=-31.1 ‰ and δ13Callo-POC ranging from −31.8 ‰ to −28.6 ‰. Comparison of DIC concentration gains and stable isotope mass balances showed that auto-POC from primary producers was the main contributor to increases in the DIC pool. Calculated OM turnover rates (0.01 to 1.3 µmol L−1 d−1) were within the range for oligotrophic water bodies. Some higher values in the metalimnion are likely due to increased availability of settling auto-POC from the photic zone. Samples from a metalimnetic oxygen minimum (MOM) also showed dominance of respiration over photosynthesis. Our work shows that respiration in temperate lentic water bodies largely depends on auto-POC production as a major carbon source. Such dependencies can influence the vulnerabilities of these aqueous systems.

Microbial carbonate rocks: composition, structures, textures, mechanisms and environments of formation. Microbiolite formation processes and environments. Article 2

Introduction. Until relatively recently, all carbonate rocks have been divided into organogenic and chemogenic rocks. The former group includes those half-composed of skeletal remains, thus representing a biological problem. The group of chemogenic carbonate rocks initially included all carbonate rocks with a crystalline structure. Later, the “chemogenicity” of formation was attributed only to pelitomorphic and microgranular varieties, while pure crystalline structures were recognised as the result of secondary recrystallization. However, the purely chemical precipitation of carbonate material from ocean waters by exceeding the solubility limit appears to be impossible. It occurs either biogenously during the formation of carbonate skeletons or biochemically as a result of changes in the acidity or alkalinity of the medium. The latter is typically implemented due to a carbonate disequilibrium between, on the one hand, the dissolved bicarbonates of calcium and magnesium and, on the other, water-dissolved carbon dioxide. The removal of the latter by photosynthetic organisms disturbs the dynamic balance and leads to an increased alkalinity and precipitation of carbonates, firstly calcium and then magnesium ones at higher pH values. Along with plants, microbial communities perform a similar function.Aim. The paper presents the results of generalization and systematization of accumulated research data on the abovementioned forms.Materials and methods. In addition to literature materials, carbonate rocks of various ages — from the Vendian and Lower Cambrian of the Siberian platform to the Crimea Neogene and sediments of contemporary oceans — were examined using macro- and microscopic (mainly) methods of studying and describing specific objects.Results. Сoccoid, tubular and fibrous formations, i.e. particular bacterial “skeletons”, represent one precipitation form. At the same time, bacterial communities produce glycocalyx, representing an extracellular polymer substance, which forms a basis for submicroscopic precipitates of carbonate minerals. In this case, specific sheet- and plate-like carbonate material precipitates can be formed. The environments for implementing such mechanisms are highly diverse. Microbiolites can be formed in water bodies, including from fresh to substantially and even abnormally saline waters, in suspended matter and at the bottom of basins, both at the stage of sedimentation and during further diagenetic processes. The most famous example of the latter are various nodules.Conclusions. The processes of sediment formation and material deposition are somewhat different. The formation of a solid phase is determined by the biochemical activity of microbiota and, first of all, the creation of geochemical conditions that contribute to the appearance of a solid carbonate material. However, the fixation of this material in a sediment is implemented either in “skeletal” ball-shaped (coccolites) and tubular (tubiphytes) forms, or by precipitation as a result of absorption on glycocalyx, or by the formation of various — both isolated individual (thrombolite microclusters, oolites and oncolites) and laminar (stromatolites) — forms.

Barium isotope composition of depleted MORB mantle constrained by basalts from the South Mid-Atlantic Ridge (5–11°S) with implication for recycled components in the convecting upper mantle

Stable barium (Ba) isotopes are emerging as tracers for the recycling of crustal material into the mantle. Small but significant Ba isotope variations have been found in global MORB (δ138/134Ba values of −0.04‰ to 0.15‰), but the processes causing these Ba isotope variations remain poorly understood. In addition, uncertainties still exist in the estimate of the Ba isotope composition of the depleted upper mantle. Here, we present a systematic study of Ba isotopes for well-characterized MORB glass samples from the South Mid-Atlantic Ridge (SMAR) between 5 and 11°S, which span a wide range of radiogenic isotope ratios and trace element contents. Our results show that the northernmost segment A0 basalts with highly depleted radiogenic isotope compositions have δ138/134Ba values ranging from −0.02 to 0.05‰. In comparison, the δ138/134Ba values of the isotopically enriched basalts from the A1-A4 segments vary from 0.02 to 0.11‰. Thus, while small, the enriched components involved can be observed to modify the Ba isotope composition of the mantle source beneath A1-A4 segments. Combining our new measurements with literature data, this study places new constraints on the Ba isotope composition of the depleted upper mantle, as well as the origin of Ba isotope heterogeneity in MORB. The Ba isotope composition of the depleted upper mantle in the absence of recycled components is estimated to have a δ138/134Ba value of 0.03 to 0.05‰, which can be adopted as the baseline for using Ba isotope ratios as a tracer of mass transfer processes between the crust and mantle. In comparison, global MORB have δ138/134Ba values ranging from −0.04‰ to 0.15‰. No global correlation is observed between Ba isotope ratios and geochemical parameters that record mantle enrichment, indicating that the Ba isotope variations in MORB cannot be simply ascribed to the addition of some single component, such as sediment. Models for melting and mixing between recycled materials and depleted mantle suggest that the variable Ba isotope compositions of the enriched MORB require a contribution from recycled altered oceanic crust and crustal sedimentary materials. Therefore, these recycled components both play important roles in the chemical budget of the convecting upper mantle, especially for incompatible elements such as Ba.

Advective structures of the bottom of lake Natron and its surroundings (Tanzania)

In this study we consider the features of the development of weakly lithified bottom sediments and the general structure of lake Natron against the background of its seasonal drying and watering. This study takes into account the laws of advection and the periodic placement of cellular zonal advective structures in space. The consedimentary structures in the lake sediments demonstrate the conditions for the formation of sodic ores and their positions. Provided space and aerial photographs depict unique genetic information about the evolution of geochemistry and the development of bottom morphology during sedimentation. This includes the presence of two sources that feed the lake - river and mud eruptions of the adjacent Oldoinyo-Lengai volcano, supposedly the only one on Earth that erupts carbonatite lavas. The combination of two sources and two processes leads to the development of an epimagmatic phreatic-hydrothermal recycling system. In it, the masses of the lake penetrate through fissure structures into the suprafocal space of the volcano, providing mud volcanism with solutions of soda masses containing organic matter of sediments. Volcanic soda eruptions are not carbonatite lavas. The morphological similarities and differences of structures are shown - small craters on the bottom of the lake, associated with the advection of thin layers of sedimentary material; large craters located nearby among volcanic strata along the shores of the lake; and both subsidence calderas and explosion calderas associated with magmatic and mud types of volcanism in the setting of strike-slip transtension.

Maize experiment in a traditional Zuni agroecosystem: nutrient composition

ABSTRACT Maize has sustained the Zuni and other peoples of the arid American Southwest for more than four millennia. In Zuni dryland agriculture, fields on alluvial fans and other valley-edge landforms are managed to receive supplemental water and nutrients by retaining storm runoff and associated sediment and organic material transported from adjoining uplands. An experiment with Zuni blue maize (Zea mays L.) and commercial hybrid maize was conducted in two Zuni fields to study traditional maize and its productivity as part of a larger study of Zuni agroecosystems. Following a closely related paper on maize growth and productivity, studies of maize nutrient composition and quality are presented here. More nutrient differences occurred between Zuni and hybrid maize than between runoff and other treatments. Zuni grain had higher concentrations of more nutrients than hybrid maize, and for several elements, there was an inverse pattern in grain vs. leaf nutrient concentration between cultivars. Zuni grain had a higher N (protein) concentration than hybrid maize, and a higher proportion of N in grain vs. leaf, indicating an ability to partition more N and other nutrients into grain. Parallel differences in maize and soil N and P were found between the two fields, though the cultivars had different P content patterns. Overall, agronomically sufficient concentrations of most nutrients were present across cultivars and treatments. Long-term production and nutrient management of maize grown without conventional irrigation or fertilization reflect a traditional agroecosystem that incorporates sustainable practices intended to maintain productivity with conservation of soil and water resources.

ANALISIS FASIES PADA FORMASI MENANGA, PEKON GUNUNGKASIH, TANGGAMUS DAN SUNGAI WAY SABU, PESAWARAN, LAMPUNG

The Menanga Formation is part of the Woyla terrane, the last large terrane amalgamated formed island of Sumatra. Woyla terrane consist of Cretaceous arc assemblage and relatively lack of research has been done on this formation in Lampung and surrounding areas. This study aims to identify the facies of the Menanga Formation. Research was carried out by making a measured stratigraphic and dividing it into facies and facies associations. The data were taken from two places, in Gunungkasih, Tanggamus and Way Sabu, Pesawaran, Lampung. The results showed that the Menanga Formation has eight facies, there are red claystone (F1), gray claystone (F2), bioturbated siltstone (F3), laminated siltstone (F4), laminated fine sandstone (F5), Parallel sandstone (F6), ripple sandstone (F7), loadcast sandstone (F8), and graded bedding sandstone (F9). The Menanga Formation facies were grouped into two facies associations, namely levee facies association (AF1) and channel facies association (AF2). AF1 consists of F1, F2, F3, F4, and F5 which shows the upper part of the turbidite sequence while AF2 consists of F5, F6, F7, F8, and F9 which shows the lower part of the turbidite sequence. The Menanga Formation shows siltstone dominance with sedimentary structure formed due to turbidit current and stacking pattern show fining upward-thinning upward indicate midfan lobe environment The Menanga Formation interpreted to be deposited in submarine fan environment whose sediment material originates from the Woyla volcanic arc.

Paradigm shifts in incinerator ash, sediment material recovery and landfill monitoring

The current paper discusses some selected developments for efficient management of the globally increasing quantity of waste. Incinerator bottom ash (IBA), the heavier ash generated during incineration of municipal waste, is currently utilised in two distinct ways. One pathway is not to fragment IBA and use it as a building material in road construction. This results in reduced landfilled residual but low metal recovery. The other way is to crush the mineral aggregate, thus maximising metal recovery but resulting in higher landfilled, end material. Here emphasis is placed on the second approach as implemented in Switzerland together with the economics and need for improvement of metal recovery from IBA and fly ash. The second theme reports on the viability of recycling mussel shells as a partial substitute for cement to stabilise dredged marine sediments mechanically. This can reduce the consumption of natural resources and lower the amount of binders used in sediment stabilisation practices. Finally, the adequacy of EU’s requirements regarding monitoring of groundwater pollution from landfills is assessed, and recommendations are provided to use bioindicators to determine the impact of landfills on surrounding vegetation.

THE ROLE OF COMMUNITIES LIVING IN WATERSHEDS TOWARDS FLOOD DISASTER MANAGEMENT : SYSTEMATIC REVIEW

Introduction. Disaster is a series of events that can threaten and disrupt human life, caused by natural and non-natural factors. A flood disaster is a natural disaster that can occur due to extreme storms in the upper watersheds, climate change, and geomorphological conditions of soil slopes, erosion, and sediment material. Flood disasters will have an impact on the social situation, people's economy, health status and death. Method. A systematic review was conducted through several stages, namely making questions, identifying, eligibility, selecting article inclusions, screening, and appraisal. The selection process was listed in the Systematic review framework and 10 articles are obtained. Later, articles were summarized and rated according to The Joanna Briggs Institute (JBI) in each article. Result&Analysis. The data shows that the results vary according to the system, and the conditions in which the study was conducted. Increasing the role of the community in flood disaster management efforts is done by increasing community knowledge, skills and experience, related to an efficient disaster management system, with several methods, namely by giving questionnaires and conducting interviews with the community or family, special training and simulations. Discussion. To increase the awareness and role of the community in managing flood disasters, several methods are applied. The simulation method is an educational effort that can be used to improve people's knowledge, skills, and experience in conducting flood management activities.

Performance assessment of a soil and water bioengineering work on the basis of the flora development and its associated ecosystem processes

The Atlantic Forest of Brazil is one of the world's 25 biodiversity hotspots, but floodplains in this region are continuously converted into agricultural or urban areas, and riverine ecosystems are affected by anthropogenic interventions. Soil and water bioengineering techniques are a component of ecological engineering that can provide nature-based solutions as an alternative or as complementary measures to conventional hydraulic or civil engineering approaches. However, there is a lack of post-evaluation of interventions and there are still great difficulties in identifying valid evaluation criteria and measurement variables, especially in countries like Brazil where soil and water bioengineering measures have only been implemented in the last decade. Another limitation to the widespread application of the techniques is the lack of knowledge about their technical performance, their impact on ecological processes and the evolution of the species used. This study aims to investigate the development of species, evaluate the technical performance of the intervention and assess the ecological benefits and processes of one of the first soil and water bioengineering riparian restoration interventions in Brazil, which was carried out in 2010 on the Pardinho river. Parameters on bank stability, development of species used in different construction techniques and its ecological benefits and ecological processes (plant species and soil fauna richness and diversity, ecological group and recruitment species, invasive species, soil organic matter and soil temperature) were collected over a period of ten years. The study proved that soil and water bioengineering works can both stabilise and control erosion, and at the same time initiate ecological processes on degraded riverbanks. The active introduction of native species has promoted vegetation succession, increased the biodiversity of both plants and soil fauna on the site and improved the site conditions. The establishment of native vegetation led to sediment and organic material deposition, which changed the local ecological conditions (e.g., soil properties, light, flow conditions) and thus facilitated rapid establishment of other plants and re-established interactions between plants and soil fauna groups. This study provides a monitoring approach which examines the technical performance of the measures and species used, as well as their impact on the ecological process over time, which is essential for establishing soil and water bioengineering techniques as the standard in the field of river engineering in Brazil. Furthermore, the results obtained will help in planning and designing future works in the field of soil and water bioengineering in Brazil, adding to the knowledge of the techniques and species to be selected, as well as supporting the evaluation of the success of interventions.

Impact of stream power gradients on storage of sediment and carbon on channel margins and floodplains

Abstract Spatial complexity impacts the resilience of river ecosystems by mediating processes that control the sources and sinks of sediment and organic material. Using four independent geochemical tracers and three morphometric indices, we show that downstream spatial gradients in stream power (Ω) predict storage of material in the channels and margins and/or floodplains. A field test in a 48 km2 watershed demonstrates that reaches with downstream decreases in Ω coincide with wider floodplains and elevated inventories of 137Cs, 210Pbex (ex—excess), and organic matter in locations of the ~3 to 20 yr floodplain. In contrast, reaches with downstream increases in Ω coincide with narrower floodplains and decreased inventories of 137Cs, 210Pbex, and organic matter. The occurrence of in-channel bedrock exposures and the activity of short-lived 7Be in within-channel sediments also correlate with downstream Ω gradients, demonstrating a link, over both short and long time scales, between withinchannel processes and floodplain-forming processes. The combined geochemical and physical characteristics demonstrate the importance of downstream gradients in sediment transport, characterized by downstream changes in stream power rather than at-a-point stream power, in determining spatial complexity in carbon and sediment storage at intermediate scales (102 to 103 m) in river systems.

Lithospheric heterogeneities of northeast India and Indo-Burma region: Geodynamic implications

• Intercontinental subduction, Cenozoic volcanism and ductile sediments imaged. • Subducting Indian slab is imaged as high-Vp whilst volcanic front by low-Vp. • Dehydration of the slab, serpentinization of the forearc mantle imaged by low-Vp. • Very less seismicity due to ductility of the sediments. • Provides valuable information for intercontinental regions of analogous tectonics. In order to understand the geodynamical implications of intercontinental subduction, Cenozoic volcanism and ductile sediments in the northeast India and Indo-Burma region, a detailed 3-D P-wave tomography has been conducted using high-quality P-wave phase data recorded by local seismographic network ascribed to different agencies of India. This approach of using local earthquake data recorded by the portable seismographs installed for limited duration also provide an opportunity to adjudge the efficacy of local seismic network, which in turn enrich our understanding of intricate issues of Seismogenesis. P-wave tomographic imaging of lithospheric structure using arrival time data from local earthquakes recorded for the northeast India and Indo-Burma region revealed strong velocity heterogeneities beneath the region. The eastward subduction of the Indian slab beneath the Burmese arc with a dipping plane of intermediate-depth earthquakes has been imaged as high velocity (high-V) zones. Under the Cenozoic volcanic front in Burma, low velocity (low-V) anomalies are imaged. The low-V at shallow crustal layers may correspond to surface geological features, sedimentary materials or the faults associated with trapped fluids or loose pelgic sediments due to episodic tectonic upheavals, dehydration of the subducting Indian slab and serpentinization of the forearc mantle beneath the region, while high-V anomalies in the same depth range possibly indicate the presence of dense crystalline rocks under compressional stress that cause seismicity in the region. The distribution of seismicity is associated with major faults and lineaments associated with the distinct structural heterogeneities. The Bengal basin and the Central Burma Molasse basin exhibit low-V anomalies with very less seismicity due to ductility of the sediments. The low-V associated with the thick piles of sediments in the Bengal (>20 km) and Central Burma Molasse (≤12 km) Basin supported by the conspicuous distribution of low-Bouger gravity anomaly, which may have contributed significantly to major load along with an overthrust load of westward moving Indo-Burma ranges over the Indian lithosphere, which may amplify the stresses already acting on the Indian Plate due to load of the Himalaya, and making the region seismically more vulnerable. The present study is found to be in a good unison to the recent studies conducted in the region using different seismo-geophysical tools to different data set. The study provides valuable information on the lithospheric structures associated with seismogenesis and volcanic activity for the intercontinental regions, elsewhere in the world for our better understanding of geodynamical processes.

KAJIAN POTENSI LONGSOR LERENG GALIAN CURAM DI KELURAHAN KALUMATA KOTA TERNATE MENGGUNAKAN GEOLISTRIK

The study of the potential for landslides on steep excavation slopes in Kalumata Village, Ternate City using geoelectricity is important to do. The location of the sirtu mining excavation which tends to be steep and close to residential areas is urgent to know the type of lithology so as to facilitate recommendations for handling to be carried out. The purpose of this study was to determine the lithological composition of the material from tracks 1, 2, and 3 along the steep excavation slope using the geoelectric resistivity Sclumberger configuration method. In addition, knowing the potential for landslides that will occur if there is no handling of steep slopes. This research is a quantitative type of field research. The research location is in the formation of lahar deposits (Gtla) and pyroclastic debris (pr) deposits. Trajectory 1 dominant lithology is 17.52 m of sand, andesite rock as an interlude and on the bedrock it is characterized by large resistivity (3241 m) while the top layer is clay type overburden. The 2 lithological paths consist of overburden, sand (7.82 m), silt (10.5 m), and andesite bedrock (resistivity 2811 m). The lithology of track 3 consists of overburden, andesite, sand (16.9 m), and andesite bedrock (4575 m). Lithology that tends to landslide in the field is overburden filled with sedimentary material in the form of clay, silt, and sandy silt (resistivity 1.5-114 m). Sand lithology with a resistivity of 479-855 m is very susceptible to landslides. Another factor causing landslides is the slope of the excavation which tends to be steep (> 60o). Keywords: Kalumata Village, Sclumberger configuration, lithology, landslide, sand

Alkenone δ2H values – a viable seawater isotope proxy? New core-top δ2HC37:3 and δ2HC37:2 data suggest inter-alkenone and alkenone-water hydrogen isotope fractionation are independent of temperature and salinity

A growing body of work has demonstrated that the δ2H values of alkenones reflect the δ2H values (δ2HH2O) and / or salinity of the fluid in which they are produced. If so, δ2Halkenone values would act as a surface seawater isotope / salinity proxy, similar to foraminiferal δ18O values, but advantaged in locations with poor carbonate preservation and / or high organic content. Nevertheless, laboratory culture, sediment trap, and water column studies have failed to consistently characterize the effects of temperature, alkenone-producing species, and salinity itself on the δ2Halkenone-salinity and -seawater isotope relationships, and a robust sedimentary alkenone-based calibration remains elusive.Most δ2Halkenone datasets report δ2HC37, i.e., combined δ2HC37:3 and δ2HC37:2 values, and differ in how they address inter-alkenone fractionation (i.e., αC37:3-C37:2). To constrain controls on alkenone hydrogen isotope systematics in the natural environment, we measured δ2H values of C37 and C38 alkenones from 20 open ocean core tops by gas chromatography-stable isotope ratio mass spectrometry after separation of di- and tri-unsaturated forms. Core-top δ2Halkenone data points are currently concentrated in extreme-salinity regions; in combination with our new values from a more moderate range of open ocean δ2HH2O / salinity values, for sedimentary alkenones, we show that 1) mean inter-alkenone hydrogen isotope fractionation is negligible (αC37:3-C37:2 = 1.002 ± 0.006), and therefore that δ2HC37:3 and δ2HC37:2 values can be measured in bulk; 2) temperature and salinity have little impact on alkenone-water fractionation (i.e., αC37-H2O) (mean 0.803 ± 0.010) relative to their expected variability in the ocean; and 3) δ2HC37 and δ2HH2O values are correlated such that statistically identical δ2HC37-, δ2HC37:3-, and δ2HC37:2-δ2HH2O regressions yield a core-top-based calibration of δ2HC37 = 1.44 (± 0.13) * δ2HH2O – 191.62 (± 1.13) ‰. This is indistinguishable from water column calibrations, suggesting a consistent response of environmental δ2HC37 values to changes in δ2HH2O values.This calibration still contains a high amount of scatter (∼ 7 ‰), perhaps attributable to irradiance, growth rate, intra- or interspecies variability, or other factors difficult to constrain in sedimentary material. Nevertheless, when applied to the well-constrained Last Glacial Maximum-to-present mean ocean δ2HH2O change of ∼ 8.8 ‰, it (1.44 ‰ δ2HC37 per 1 ‰ δ2HH2O change) reproduces the mean δ2HC37 Modern – δ2HC37 LGM shift observed from the handful of extant down-core records, legitimizing the observed lack of temperature or salinity effects on αC37-H2O. This suggests that combined δ2HC37:3 + δ2HC37:2 values are a valid proxy for δ2HH2O values in open ocean settings where E. huxleyi and G. oceanica dominate, although additional efforts will be required to refine the core-top calibration for universal use.

Control of the preservation of sympagic algal material in surficial sediments of central and eastern Baffin Bay by bactericidal hydroperoxides and free fatty acids

Monounsaturated fatty acids and their oxidation products were quantified in surficial sediments (0–1 cm) dominated by sympagic (ice-associated) material released at the end of the ice melt collected in summer in central and eastern Baffin Bay during the 2016 GreenEdge campaign. Sympagic algae preservation towards bacterial mineralization was monitored based on intact and oxidized C16:1ω7 (palmitoleic) acid, and oxidation products of C18:1ω7 (vaccenic) and C16:1ω5 acids provided insights on the photooxidative and autoxidative alterations of bacteria present in these sediment samples. Preservation of sympagic algal material appeared to be highest at the stations that were relatively unaffected by copepod grazing and that contained strongly autoxidized (and thus inactive) bacteria. Analysis of sinking particles collected with a drifting trap showed an intense flux of highly photooxidized ice algae in early July that was dominated by Navicula spp. and associated with bacteria that had also been strongly altered by photooxidative processes. It is proposed that subsequent homolytic decomposition of the hydroperoxides resulting from this intense photooxidation may have driven the strong autoxidation of sympagic algae and bacteria observed in the sediments. The lack of colonization of sympagic material by active benthic bacteria observed at some of the stations investigated was attributed to its high content in deleterious autoxidative hydroperoxides and free fatty acids (reaching for example 107% and 22% of residual palmitoleic acid, respectively, at station 605).

The results of complex interpretation of seismic survey and well data in Gurgan Deniz area

As a result of combined analysis of seismic surveys conducted in Gurgan-deniz and neighboring areas and logging data as well, the geological structure of the studied area was specified, various seismic attributes (both as by seismic cubes and by separate seismic surfaces) were calculated. To have a clear insight about the lithofacies variability of the studied area, corresponding 3D models have been developed. With the purpose of restoring the sedimentation conditions, a facies analysis of the area based on the visual study of the length and configuration of seismic reflections, as well as seismic amplitudes has been carried out, the changes of the power of separate intervals in which we are interested have been studied and the logging of the facies conducted. To define the connection between the dynamic parameters of seismic records and geological properties of the area in the promising intervals, several attributes (Sweetness, RMS, Instantaneous Frequency, Variance etc.) have been calculated and analyzed. The calculation have been conducted in a large diapason for all productive horizons (marked as potential reservoir). Sharp changes in the composition of rocks in the studied area are associated with a periodic transgression and regression, as well as with the fluviation. Three types of geological phenomena may occur during specific periods of cycle turns of rising and lowering of sea level: progradation and regression (recession of the sea), retrogradation or transgression (sea movement towards shore) and aggradation (comparatively stable state of sea level). In the view of sharp variation of lithologic composition of the sediments, predominantly in the bottom of Productive Series (PT), we can conclude that highlighted facies are characteristic for specific parts of the studied area. When highlighting the facies, the direction of sedimentation material brought by the rivers and source of nourishment has been revealed. According to the results obtained, we suppose that almost each lithofacies type has its own distribution area. Therefore, the fluviation plays a significant role in the distribution of the facies in the studied area of the Caspian basin, as well as in the accumulation of hydrocarbons. Complex research surveys carried out enabled to mark specific perspective oil-gas bearing objects in Gurgan-deniz and neighboring areas.

Effect of sediment gradation on scour by symmetric crossing jets: an experimental investigation

Abstract A laboratory study with 162 experiments was designed and conducted to investigate the effect of three non-uniform sediment samples on the scour morphology by the symmetric crossing jets. The bed sediment materials with close median diameter values and different non-uniformities were utilized to investigate the scour at various crossing angles. The results were also compared with the equivalent single jet. The proper novel relationships were presented to predict the scour hole depth, and dimensions. The results showed that at a crossing angle of 30° with low and medium tailwater depth, the scour depth increases with increasing the non-uniformity of the bed materials. At the crossing angle of 30°, the armor layer was created perfectly that was thick on the bottom of the scour hole, but for the crossing angles of 70° and 110° it was thin and was a mixture of the coarse and fine particles. At low tailwater depth at the crossing angles of 70° and 110°, by increasing the non-uniformity of the sediments, the scour tended to be more asymmetric. At the high tailwater depth, for the crossing angles of 70° and 110° the scouring was less than that of the crossing angle of 30° and single jet.

The influence of sedimentary and diagenetic heterogeneity on the radionuclide diffusion in the sandy facies of the Opalinus Clay at the core scale

Molecular diffusion is an important transport mechanism for radionuclide migration in low-permeable argillaceous host rock such as Opalinus Clay (OPA). In this study, the influence of sedimentary and diagenetic heterogeneity on heterogeneous diffusion in sandy facies of OPA (SF-OPA) from lamina scale to drill core scale is investigated using an upscaling workflow to model diffusive transport from the pore scale to the core scale. Our numerical results based on the simplified structural model show fast diffusion fronts in clay laminae (7 mm displacement after 6 days of diffusion) and slow diffusion fronts in carbonate lenses and sand laminae (4 mm displacement after 6 days of diffusion), demonstrating the endmembers of heterogeneous diffusion patterns in SF-OPA. Moreover, our results show that the diffusion fronts begin to homogenize after 22 days of diffusion with the specific influence of carbonate lenses (here: length = 1 cm, thickness = 3 mm). This example illustrates how material heterogeneities affect heterogeneous diffusion on a small temporal and spatial scale. The sensitivity studies show that the diffusion length and homogenization time increase by up to 190% when the length and thickness of the carbonate lenses are doubled. Using four compositional endmembers, we show the generalized diffusion behavior to demonstrate the influence of thin laminae and thick layers as well as dispersed small and large diagenetic concretions on the homogeneity of diffusion. These results demonstrate that the geometry of sedimentary and diagenetic material and the subfacies composition are the controlling factors for quantifying diffusion length and homogenization time. This study provides quantitative constraints on the temporal and spatial evolution of heterogeneous diffusion at the core scale. This quantitatively improves the predictability of radionuclide migration in host rocks as a function of compositional and pore network-specific parameters.

New micromechanical data and modelling framework for the elastic response of calcareous mudstones

Mudstones are amongst the most compositionally diverse sedimentary materials in nature; constraining their elastic properties is crucial in many subsurface engineering scenarios. Mudstones with high calcium carbonate contents are common but have received little attention in micromechanical studies. Using the Eagle Ford formation as an example, we present a new conceptual framework for micromechanical modelling calcareous mudstones, with the aim of predicting the macroscopic elastic response of mudstones to address gaps left by limited core-scale data. The model accounts for the microstructural differences with argillaceous mudstones and implement it in a mean-field homogenisation framework. This allows us to model elastic stiffness from the scale of microcrystalline calcite up to the scale of the undamaged poro-mineralogical skeleton. We present results of a comprehensive micromechanical characterisation of the Eagle Ford, adding to the data available for calcareous mudstones. We show that the contribution of calcite to the overall anisotropy is non-negligible, with appropriate transversely isotropic elastic constants for the carbonate phase calculated. We demonstrate the use of high-load nanoindentation tests to successfully calibrate a micromechanical model. This is achieved by direct comparison of model results against the inversion of high-load indentation data. Finally, the applicability of our modelling scheme and material parameters to model other calcareous mudstones is explored using core-scale data from the Williston basin of Canada, demonstrating good agreement.