Sedimentary Processes Research Articles

Emergent ecology in a microscale model of the surface ocean.

Microbial processes operate at the microscale, which is not resolved by existing ecosystem models. Here, we present a novel model that simulates a 1 mL three-dimensional cube using a hybrid Lagrangian-Eulerian approach, at ecologically relevant timescales. The model simulates individual microbes, including three phytoplankton size classes with healthy, senescent, and dead lifecycle stages; copiotrophic and oligotrophic heterotrophic bacteria; and dissolved organic matter at 50 µm resolution. Diffusion, shear, sedimentation, chemotaxis, and attachment processes are explicitly resolved. The emerging quantitative representation of the ecosystem shows that (1) copiotrophs grow mostly attached to eukaryotic phytoplankters and get almost all of their carbon from them vs. oligotrophs that grow on exudates and lysates of cyanobacteria; (2) contrasting diel patterns in substrate appearance in the phycosphere vs. ambient water and growth of particle-associated copiotrophs vs. free-living oligotrophs; (3) attached bacteria reduce carbon flux from the phycosphere, lowering chemotactic efficiency toward eukaryotes below that toward cyanobacteria; (4) shear reduces chemotactic efficiency and fitness of the copiotroph; and (5) the main benefit of chemotaxis is to locate attachment partners. These patterns are consistent with available observations. Our study provides insights into the microscale ecology of marine bacteria, and the open-source code is a tool for further research in this area.IMPORTANCEA large amount of global CO2 fixation is performed by marine phytoplankton, and a substantial fraction of that is released as dissolved organic carbon and further processed by heterotrophic bacteria. The interaction between phytoplankton and bacteria, i.e., the carbon flux between them, is therefore an important process in the global carbon and climate system. Some bacteria have developed specialized behavioral traits, like swimming and attachment, to increase their carbon acquisition. These interactions occur at the micrometer scale, for example, the immediate vicinity of phytoplankters (the phycosphere), but existing biogeochemical models typically only simulate down to the 1 meter vertical or ~100 kilometer horizontal scale. We present a new microscale model and use it to predict fluxes and other features in the surface ocean. The model makes important predictions about the fluxes between various types of phytoplankton and bacteria and the role of behavioral traits, and it provides a basis and tool for further research in this area.

Estimating Vertical Distribution of Total Suspended Matter in Coastal Waters Using Remote-Sensing Approaches

The vertical distribution of the marine total suspended matter (TSM) concentration significantly influences marine material transport, sedimentation processes, and biogeochemical cycles. Traditional field observations are constrained by limited spatial and temporal coverage, necessitating the use of remote-sensing technology to comprehensively understand TSM variations over extensive areas and periods. This study proposes a remote-sensing approach to estimate the vertical distribution of TSM concentrations using MODIS satellite data, with the Bohai Sea and Yellow Sea (BSYS) as a case study. Extensive field measurements across various hydrological conditions and seasons enabled accurate reconstruction of in situ TSM vertical distributions from bio-optical parameters, including the attenuation coefficient, particle backscattering coefficient, particle size, and number concentration, achieving a determination coefficient of 0.90 and a mean absolute percentage error of 26.5%. In situ measurements revealed two distinct TSM vertical profile types (vertically uniform and increasing) and significant variation in TSM profiles in the BSYS. Using surface TSM concentrations, wind speed, and water depth, we developed and validated a remote-sensing approach to classify TSM vertical profile types, achieving an accuracy of 84.3%. Combining this classification with a layer-to-layer regression model, we successfully estimated TSM vertical profiles from MODIS observation. Long-term MODIS product analysis revealed significant spatiotemporal variations in TSM vertical distributions and column-integrated TSM concentrations, particularly in nearshore regions. These findings provide valuable insights for studying marine sedimentation and biological processes and offer a reference for the remote-sensing estimation of the TSM vertical distribution in other marine regions.

Simultaneous influences of hematocrit in the erythrocyte medium on erythrocyte aggregation and sedimentation: a kinetic study by a laser scattering technique

The erythrocyte aggregation is an important physiological phenomenon in the circulation of blood. It is a basic characteristic of normal blood that plays a major role in the cardiovascular system, especially in the microcirculation. This study explained the kinetics of single cells rouleaux formation one- dimensional aggregate and three- dimensional aggregate, during simultaneous, and the effect of hematocrit on the process of aggregation and sedimentation. The present study was done on forty one healthy subjects. Laser light is passed through a well mixed sample of blood and the forward scattered light intensities recorded continuously. The samples were prepared with different hematocrit, (10%, 15%, 20%, and 25%). Increasing the hematocrit, (10%, 15%, 20%, and 25%) had significantly decreased the rate of rouleaux formation (P< 0.005) but increase in the rate of one and three dimensional aggregate formation. On the other hand the sedimentation rate is decreased significantly (P

Design of Flat Loop Reactor with Bubble Column Circulation, Algae Growing Equipment

Abstract Based on the flow modeling and operational experience of the previous cylindrical loop reactor, we designed a sheet reactor combined with a loop reactor. The design with a cylindrical cross-section was applied to an equivalent cross-section (sheet) of several squares arranged next to each other. In accordance with the sedimentation processes experienced in the outlet branch, we created an algae trap, thereby reducing the flow to the level necessary for sedimentation. With this, I would like to achieve the already experienced, nearly 10-fold increase in algae concentration compared to the one in the mainstream.

Experimental study into the sedimentation process of solids of different origin

Sedimentation refers to the first stage of wastewater treatment from mechanical impurities. Its rate depends on the density and particle size of impurities, as well as the density and viscosity of dispersion medium. In industrial sedimentation tanks, particle settling can occur in laminar, transient or turbulent modes. Aim. To establish the criterion equations and their coefficients for sedimentation processes of sand, glass and polyamide granules. Sedimentation of sand particles of 0.001– 0.003 m, spherical glass particles with the diameter of 0.0025–0.004 m and polyamide granules with the volume-surface mean diameter of 0.0022–0.003 m was carried out in a measured glass cylinder filled with distilled water. Each solid particle was measured, then, it came into contact with the water surface by means of tweezers, and released, starting to settle to the bottom of the cylinder under the action of gravity. A stopwatch was used to time the particle passaging between the marks of the measured cylinder. Calculations were performed using dimensional analysis. According to the test results, the dependences of the Reynolds number on the Archimedes number were established for the sedimentation of sand particles and polyamide granules in the transient mode, while spherical glass particles in the turbulent mode. In addition, the criterion equations of the solid particles sedimentation in the liquid were derived. The coefficients for these equations were experimentally determined. The equations and coefficients obtained in the study can be used in the design of settling tanks for mechanical treatment of wastewater to remove sand, glass and polymer particles.

Holocene paleoenvironment of the Nihewan Basin, China, inferred from high-resolution luminescence dating and a multiproxy analysis of gully sediments

As a pivotal region for studying early human occupation in East Asia, the Nihewan Basin has witnessed numerous studies on Paleolithic sites and associated paleoenvironmental records. However, little attention has been given to the Holocene period, despite the basin being a crossroads for the exchange of NE China Neolithic cultures. In the central part of the Nihewan Basin, we found a gully sediment section with a thickness of ∼9 m, which exhibits clear parallel bedding throughout. The section is composed of ten sediment layers (Layers 10–1 from bottom to top), from which three distinct dark-colored soil layers (Layers 8, 4 and 2) and two erosion surfaces (between Layers 10 and 9, and Layers 2 and 1) were identified. Forty-four sediment samples from the section were optically dated, and the obtained ages were refined using Bayesian statistical modeling. The age-depth relationship and sedimentary characteristics suggest that the sedimentation process of Layers 9–2 was continuous. To reconstruct the paleoenvironment, the grain-size distribution, magnetic susceptibility, and pollen content of the sediments were analyzed. The three soil layers exhibit high magnetic susceptibility values. Based on these climatic proxies, five climate stages were recognized. From ∼12.7 to ∼6.8 ka, the climate in the basin region was cold and dry. The period between ∼6.8 and ∼5.4 ka was marked by optimal climate conditions that led to soil formation. Subsequently, the climate was colder and drier during the period of ∼5.4 – ∼4.0 ka, and transitioned to warm and wet conditions again from ∼4.0 to ∼2.7 ka. Another stage of soil formation occurred between ∼2.7 and ∼1.7 ka, during which the climate was predominantly warm and humid, albeit punctuated by a brief interval of colder and drier conditions. These climate variations coincided with cultural evolution stages within the basin, highlighting a close relationship between environmental change and human adaptation.

Biogeochemical processes in sediments of lakes in the Kenozersky National Park

Biogeochemical processes in sediments of lakes in the Kenozersky National Park

Detrital clay mineral input reconstructed based on weathering records and its influence on organic matter enrichment: A case study of the Paleogene Shahejie Formation in the Dongpu Sag, Bohai Bay Basin

As major components of shales, clay minerals are important for investigating unconventional petroleum geology. However, there are few quantitative methods for investigating possible inputs of clay minerals during sedimentary processes. In this study, shales from the Shahejie Formation in the Dongpu Sag, Bohai Bay Basin, were chosen for investigating clay mineral inputs. The shales are abundant in a variety of clay minerals. The shales, uniformly derived from felsic igneous rocks, underwent mild K metasomatism. Thus, the detrital clay mineral input was primarily influenced by weathering intensity. Accordingly, representative samples subjected to varying weathering intensities were selected to identify detrital and diagenetic clay minerals. Kaolinite and chlorite are of detrital origin. Illite and illite/smectite mixed layers (I/S) have both detrital and diagenetic origins. The precursor minerals of diagenetic minerals can be identified based on their morphological and elemental characteristics. After quantifying the area proportions of various clay minerals, the detrital clay mineral compositions of selected samples were calculated. Further analysis indicated that the detrital illite content and the detrital chlorite content are closely related, while the detrital smectite content correlates well with the chemical index of alteration (CIA). Based on the preceding analysis, the fitting formulas were established to quantitatively characterize the input of detrital clay minerals. The shales from the north sag had a high input of detrital smectite, whereas the shales from the south sag had a high input of detrital illite. Consequently, the shales from the north sag contain more organic matter than those from the south sag.

Tracing rate and extent of human-induced hypoxia during the last 200 years in the mesotrophic lake, Tiefer See (NE Germany)

Abstract. The global spread of lake hypoxia, [O2] < 2 mg L−1, during the last 2 centuries has had a severe impact on ecological systems and sedimentation processes. While the occurrence of hypoxia was observed in many lakes, a detailed quantification of hypoxia spread at centennial timescales remained largely unquantified. We track the evolution of hypoxia and its controls during the past 200 years in a lake, Tiefer See (TSK; NE Germany), using 17 gravity cores recovered from between 10 and 62 m water depth in combination with lake monitoring data. Lake hypoxia was associated with the onset of varve preservation in the TSK and has been dated by varve counting to 1918 ± 1 at 62 m water depth and reached a lake floor depth of 16 m in 1997 ± 1. This indicates that oxygen concentration fell below the threshold for varve preservation at the lake floor (> 16 m). Sediment cores at 10–12 m depth do not contain varves indicating good oxygenation of the upper-water column. Monitoring data show that the threshold for hypoxia, and the intensity and duration of hypoxia which are sufficient for varve preservation, is a period of 5 months of [O2] < 5 mg L−1 and 2 months of [O2] < 2 mg L−1. Detailed total organic carbon (TOC), δ13Corg, and X-ray fluorescence (XRF) core scanning analyses of the short cores indicate that the decline in dissolved oxygen (DO) started several decades prior to the varve preservation. This proves a change in the depositional conditions in the lake, following a transition phase of several decades during which varves were not preserved. Furthermore, varve preservation does occur at seasonal stratification and does not necessarily require permanent stratification.

Evolution process of chemical weathering and sediment sources in the Makran Continental margin since the Younger Dryas

The chemical weathering processes and sedimentary source evolution since the Younger Dryas (YD) in the low-latitude arid continental margin have been investigated. Two sediment cores, MK07G and MK09G, were retrieved from the Makran continental margin in the northern Arabian Sea and subjected to analyses of major and trace elements, along with AMS14C dating. The results show that since the YD, the weathered parent rocks of Makran sediments have remained relatively stable, predominantly consisting of felsic rocks, with some contributions from mafic rocks. The Makran sediments exhibit initial to moderate weathering, with no discernible effects from grain size sorting or disturbances from sediment recycling, indicating primary deposition. Significant contributions of terrigenous eolian dust from surrounding continents (e.g., the Indian subcontinent, Arabian Peninsula, and northeastern Africa) were identified, along with riverine inputs from the Dasht River and fine-grained components from the Late Pleistocene Indus delta sediment, as well as proximal basin sedimentation. The evolution of sediment sources in the study area is significantly influenced by the Indian Monsoon and westerly wind systems, with intensified monsoon phases and westerly conditions correlating with increased fluvial input. Furthermore, chemical weathering processes since the YD are closely linked to local precipitation patterns, where intensified rainfall enhances weathering intensity. Records from the Makran continental margin indicate a teleconnection between chemical weathering and sedimentary processes in the Arabian Sea and Bond events in the North Atlantic, highlighting the extensive influence of Northern Hemisphere climate fluctuations.

Mineralization characteristics of Lead-Zinc-Copper deposits in Akdağmadeni Region (Northern Central Anatolia, Türkiye): Integration of field study, geochemical, isotope, and geophysical data

The Akdağmadeni region is one of the important Pb-Zn-Cu metallogenic provinces in Türkiye. Most of the Pb-Zn-Cu deposits in the region are located near granitoid intrusions within metamorphic rocks, and they are typically classified as skarn-type ores associated with granitoids. However, no relationship has been determined between the Başçatak prospect and any granitoid outcrop. This raises the question of whether the Pb-Zn-Cu mineralization in the region is related to granitoids or if magmatic processes remobilized pre-existing mineralization. Observations from field studies suggest that mineralization in the Başçatak prospect is a stratiform type, metamorphosed occurrence that might have occurred earlier than the granitic intrusions. The geochemical data indicated that the granitoids have low-grade, subeconomic Cu potential and no Zn productivity potential, supporting these observations. Geophysical data also show that there is no intrusive body beneath this prospect. Granitoid-related deposits (Karapir - Ortaköy and Akçakışla) exhibit two distinct occurrences around the contact between the granite and the surrounding metamorphic rocks. The first type of occurrence (O-1) is formed at the contact and contains magnetite, pyrrhotite, and chalcopyrite. The second type of occurrence (O-2) is located outside the contact and is rich in sphalerite and galena. Both O-1 and O-2 contain skarn minerals along with ore minerals. The δ34S values of sulfide minerals from the deposits range from −0,7 to 7,5 ‰ (V-CDT). These values overlap with those of both magmatic sulfur and reduced sulfur from seawater-dissolved sulfate, making it difficult to suggest a sulfur source without additional data. Lead isotope compositions of the galenas from all deposits plot above the average crustal growth curve, suggesting an upper crustal and orogenic source similar to Western Mediterranean and Türkiye type materials described in the literature for the lead, source in different time intervals. Furthermore, Pb isotope geochemistry suggests a contemporaneous age with the host metamorphic rocks (Carboniferous – Lower Permian) for the Başçatak prospect. These results support observations indicating a syn-genetic formation for the Başçatak prospect. The age range of granite-related deposits forms two sub-groups:105–77 Ma and 61–50 Ma corresponding to the Upper Cretaceous and Paleocene transition. These data indicate that that the galenas were formed in two different stages in these mineralizations. Stratiform mineralization in the Başçatak prospect likely formed either through exhalative sedimentary processes by hydrothermal fluids or through chemical sedimentary processes under reductive conditions in a marine environment during metamorphism. O-1 appears to have been formed by hydrothermal fluids developed during granitic magmatism. A plausible formation process for O-2 involves the leaching of sulfur, lead and other metals from Başçatak type enrichments in metamorphics, with transportation and deposition within the epidotized calc-schist and marbles outside the granitoid contacts. The uplift of granitic intrusions prepared the channels and depositional environment for O-2 and caused heating of the hydrothermal fluids during this mineralization period.

Runoff variation alters estuarine sediment microbiome and nitrogen removal processes by affecting salinity

Runoff variations shape the dynamics of the estuarine environmental factors, profoundly influencing the nitrogen cycle in estuarine sediments. However, our understanding of how these changes regulate microbially-mediated nitrogen removal processes remains limited. In this study, the impacts of changes in environmental factors caused by normal and low runoffs on denitrification and anammox in sediments of the Liao River Estuary in China, were investigated, using continuous-flow experiments combined with 15N tracing techniques and molecular methods. Results indicated that denitrification was the main nitrogen removal process in estuarine sediments under both runoff conditions. Elevated salinity under low runoff condition increased the abundance of nitrifying bacteria (Nitrospina, Nitrosomonas and Nitrosomonadaceae), thereby promoting the coupled nitrification-denitrification nitrogen removal process. Furthermore, seawater intrusion under low runoff contributed to dilute nitrite concentrations, resulting in decreased denitrification rates in sediments. Overall, this study highlighted the impacts of runoff variations on biological nitrogen removal process through affecting environmental factors, gene abundance and microbial community in the estuary.

Oil and Gas Content of the South Caspian Basin

Abstract —We have compiled maps of areal isotope composition changes and constructed graphs of gas HC distribution depending on the stratigraphic age of the host rocks and graphs of isotope composition changes depending on the depth of sampling to study the hydrocarbon potential of the deep-seated oil and gas pools of the South Caspian Basin. The genesis of gas was studied using the techniques elaborated by M. Schoell and A. James. Two stages of hydrocarbon formation have been established by study of various kinds of gas manifestation. The first stage (Miocene–Eocene) began in the deposits underlying the Productive Series and continued up to the deposits of the latter. This stage was characterized by a frequent change in the directions of both downward and upward movements of gases. The second stage of hydrocarbon formation (Anthropogene–Pliocene) began in the deposits of the Productive Series and was characterized by a change in the regional geodynamic setting. Avalanche sedimentation and the predominance of downward movements over upward ones favored the accumulation of thick sediments at the time when the Productive Series formed. The sedimentation and tectonic processes (downwarping) in the deep-water zone of the basin led to harsh thermobaric conditions in the sedimentary strata. A detailed analysis of the results of gas survey in the deep-water zone of the South Caspian Basin has shown gas generation with a predominance of two components, methane and ethane. Study of the trends of temporal and areal hydrocarbon migration and of the areas of oil and gas generation makes it possible to reveal structures with evidence for large and giant hydrocarbon reserves. We have established that gas hydrocarbons in the bottom and upper-section sediments of the southern Caspian Sea are intimately related to the sources of hydrocarbons, their migration, and other processes running in the deep-seated sediments and in the upper section.

Geomorphological and Sedimentological Rationale for Staged Sand Dam Construction

ABSTRACTStream sediment transport results from a convolution of climate, weather, geology, topography, biology, and human influence. In addition to providing water and food security for rural dryland communities, sand dams—small weirs designed to trap only the coarse fractions of transported sediments in seasonal and ephemeral streams—highlight many complexities of geomorphological dynamics. Sand dams store water in interstitial riverbed pores and the size of deposited sediment particles largely determines the recoverability of stored water: Fine materials limit transmission and provide lower volumetric yield. In this study, we seek to identify a practical method for evaluating the theoretical effect of staged sand dam crest construction on key sediment‐trapping processes for a proposed dam site. We argue that the Rouse number provides a useful criterion for identifying regimes where the target material grades are trapped. These ideas were tested using sediment data collected in Kenya and US Army Corps of Engineers River Analysis System numerical simulations to evaluate the sensitivity of sedimentation processes to crest height. We show that constructing sand dams in stages results in more targeted trapping of coarse material. Sedimentation is shown to be more sensitive to variation in crest height than the flood hydrograph, especially when a dam's crest height is small. By introducing a method to assess the necessity and inform design of staged crest construction based on local flow dynamics, this study offers a framework for optimising sand dam performance in data‐scarce environments. This approach provides a means to balance construction costs with expected benefits, enhancing the sustainability and functionality of sand dams in arid and semi‐arid regions.

Influence of climate and marine transgression on Mesozoic–Cenozoic diagenesis of clastic rocks in the Tabei Uplift, Tarim Basin, China

The Mesozoic–Cenozoic clastic rocks in the Tabei Uplift form one of the most hydrocarbon-rich zones in the Tarim Basin of China. Understanding how diagenesis has affected the petrophysical properties of the sandstone is crucial for developing regional exploration strategies. Although most studies have investigated the physical conditions during sedimentation and chemical processes during diagenesis, the hydrochemical environment during sedimentation and subsequent diagenesis has received little attention. This study employed petrographic observations, paleo-geothermal reconstructions, and paleoenvironmental analysis to constrain the regional climatic conditions, hydrochemical environment of deposition, and diagenetic features of clastic rocks in the Tabei Uplift. The sandstone at depths of 3500–6000 m is located mainly in the A phase of the middle diagenetic stage, and exhibits three types of diagenesis. Triassic–Jurassic sandstones are dominated by silica, kaolinite, and chlorite cements, Cretaceous sandstones by mainly carbonate cements, and Paleogene sandstones by carbonate and evaporite cements. These diagenetic stages correspond to paleoclimatic changes during the earliest Late Jurassic and the maximum marine transgressions of the Proto-Tethys during the Paleogene, thereby highlighting the influence of climatic change and transgressions on the water conditions during deposition and the type of diagenesis.

Analyzing sedimentation patterns in the Naumure Multipurpose Project (NMP) reservoir using 1D HEC-RAS modeling

Naumure Multipurpose Project (NMP) featuring a 169 m high Concrete Face Rock Filled Dam (CFRD) is the proposed reservoir project in the West Rapti River with an installed capacity of 218.34 MW. Most of the rivers in Nepal carry significant sediment loads that will consequently catalyze reservoir sedimentation. This phenomenon prevails as the primary factor in reducing reservoirs useful life, making ineffective for both flood control and hydroelectricity generation. Ultimately, such process of sedimentation has adverse impacts on projects economic feasibility and long-term sustainability. Therefore, the objective of this research was to examine the expected sediment deposition pattern in the NMP reservoir throughout its operational period by employing 1D HEC-RAS model to simulate the sedimentation process. The model was simulated for 10, 20, 30, 40 and 50 years. Yang’s equation as a sediment transport function, Active layer as a bed sorting method and Toffaleti as a fall velocity method were best suited for the river reach. The delta deposition was formed between 11 km and 22 km upstream of the dam region in the Jhimruk river, with the sediment deposition depth reaching peaks of about 23 m, 38 m, 39 m, 41 m and 49 m in 10, 20, 30, 40 and 50 years, respectively. Similarly, the delta deposition was formed between 13 km and 33 km upstream of dam region in the Madi river, with the sediment deposition depth reaching peaks of about 47 m, 62 m, 60 m, 68 m and 75 m in 10, 20, 30, 40 and 50 years respectively. Headcutting of delta deposition occurred between 20 and 30 year due to high flood during low stage of reservoir. Furthermore, the study revealed that about 6.22%, 11.61%, 15.94%, 22.96% and 25.65% of the storage capacity of NMP reservoir will be depleted in 10, 20, 30, 40 and 50 years respectively.

Geochronology, in-situ elements and sulfur isotopes of sulfides from the Songjiashan cobalt-iron deposit in the Zhongtiao mountains of North China Craton: Implications for cobalt occurrence and ore genesis

The Songjiashan Co-Fe deposit in the central part of the “Tongshan skylight” on the southeastern edge of the Zhongtiao Mountains is hosted by the volcanic-sedimentary rock series of the Paleoproterozoic Songjiashan Group. The spatial distribution of the orebodies is controlled by south-north trending rock units. Based on microscopic observations, the dominant ore minerals included magnetite, pyrite, chalcopyrite, carrollite, and linnaeite, while gangue minerals comprised quartz, calcite, sericite, and chlorite. Cobalt-iron ores had massive, banded, disseminated, and veinlet texture, and alteration of the host rocks included silicification, sericitization, pyritization, carbonation, and chloritization. Mineralization processes of the Songjiashan deposit were grouped into three periods: sedimentation, metamorphism, and hydrothermal. The Co concentrations in hydrothermal pyrite (Py-III) varied from 1.05 % to 3.75 %, with an average of 2.45 %. Cobalt in pyrite was homogeneously distributed and inversely correlated to Fe, indicating that Co isomorphically replaced Fe in pyrite. The characteristic Co/Ni ratio of pyrite varied greatly, ranging from 0.1 to 1000, reflecting various genetic types of sedimentation, metamorphism, and hydrothermal mineralization, with the main mineralization period primarily related to hydrothermal activities. Zircon U-Pb geochronology of the host rock and Re-Os isochron of Co-bearing pyrites indicate that Co mineralization mainly occurred at ∼2100 Ma. In-situ S isotopic analysis of sulfides reveals two peak δ34S values of 5–9 ‰ and 12–16 ‰. We interpret that the former value reflects the mixing of volcanic and marine sulfate sources, while the latter value is mainly artributted to marine sulfate sources. All δ34S values were lower than those of Proterozoic marine sulfates (15–20 ‰). Accordingly, we infer that thermochemical sulfate reduction plays a key role in marine sulfate reduction, and that the formation of Co-rich ore bodies in the Songjiashan deposit have undergone processes of initial sedimentation, metamorphism-deformation, and subsequent hydrothermal overprinting. Genetically, we suggest that the Songjiashan deposit belongs to a sedimentary-metamorphic hydrothermal superposition type Co-Fe deposit.

Geochemical Markers of Organic Matter Transformation in the Eastern Part of the Laptev Sea

The sources of supply and transformation of organic matter (OM) during the transition from the dissolved form to suspension, fluffy and bottom sediments on the meridional transect from the Lena River delta to the continental slope were described (depths from 10 to 2390 m, cruise 63 of the R/V Akademik Mstislav Keldysh, September 2015). The results of the study of OM molecular markers showed that dissolved and suspended OM of marine and terrigenous origin biodegrades in the water column and practically does not accumulate in bottom sediments. Thus, OM of the Lena river runoff does not contribute to the formation of OM in the bottom sediments in the summer period. On the outer shelf, an area of influence of ice bloom on the sedimentation process was revealed.

Predict: Assessing the Seismic Response in the city of Rome, Part 1. New Data for a Geologic Overview

This work presents the preliminary results of the stratigraphic, paleomagnetic, micropaleontologic and geochronologic investigations carried out on the cores of three boreholes performed in the historic center of Rome within the Predict Project, aimed at evaluating the seismic response within the City through the 3D modeling of the subsoil. Moreover, we have integrated the investigations on the cores of four previously performed boreholes and we use this larger dataset to provide an objective element for the interpretation and validation of a large databank of paper stratigraphies of boreholes carried out for civil engineering purposes in the Roman area. The new data are presented within an exhaustive review of state of the art on the scientific knowledge on the geology of Rome, aimed at providing an updated background for the Quaternary scientists, seismologists, engineers and professional technicians operating in this region. Within this framework, we provide a detailed reconstruction of the chronostratigraphic setting in central Rome, highlighting a coherent picture within the glacio‐eustatic control on the sedimentary processes and providing the background geological input data for the creation of a geo‐database in a dynamic GIS environment, which is the subject of a forthcoming sister‐paper.

Source and Origin of Subsurface Brine of the Kongquehe Sag Area in Western Lop Nur, China

The Kongquehe Sag, located in the western Lop Nur, has abundant pore subsurface brine. In order to study the source and origin, we tested and analyzed the hydrochemical composition and stable isotopes of the subsurface brine. The findings reveal that the brine exhibits a moderate to low degree of mineralization, with values ranging from 50.50 g/L to 91.14 g/L. The stable isotope compositions of unconfined and confined waters are different, with the mean values of δD being −8.00‰ and −51.75‰ and the mean values of δ18O being 10.08‰ and −6.01‰. These values are indicative of an intense evaporative environment prevalent in the Kongquehe Sag area. Furthermore, the 87Sr/86Sr ratios vary between 0.710642 and 0.710837, and δ34S values range from 9.2 to 10.7. These data suggest the long-term evolution of sulfur substances, predominantly through dissolution and sedimentation processes, with minimal influence from redox reactions. The data garnered from this research not only offer a novel perspective of the insights gained into the hydrochemical characteristics and the stable isotope signatures of the brines in the Kongquehe Sag area but also enriches the theoretical framework concerning the source and origin of subsurface brines, potentially informing future exploration strategies.