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The research conducted in this study is an attempt to quantitatively and qualitatively supplement the still insufficient knowledge on aeolian processes under polar conditions, where some of the most visible and dynamic climate changes are occurring. This study presents the results of rounding and matting analysis of quartz grains collected from aeolian deposition traps located in the Ebba Valley, Svalbard. The results are based on four summer field campaigns (2015–2018). Quartz grains with a diameter of 0.8–1.0 mm were selected and subjected to further analysis under a microscope, which allowed them to be divided into six individual classes. The nature of the grains can largely indicate the environmental conditions in which the material was transported. The collected material was dominated by grains with a low degree of roundness, which may indicate relatively short fluvial or aeolian transport. The small amounts of typically matted quartz grains may indicate low environmental dynamics and short transport, as well as the fact that large amounts of the material are blown from the valley interior to the nearby bay and fjord. This study highlights the importance of a fresh sediment supply from two main sources (i.e., moraines and rivers) and their subsequent aeolian redistribution, particularly in a wind-channelled valley environment. These findings underscore the complex interactions between aeolian processes and environmental conditions in cold regions. Climate change may significantly affect the magnitude of aeolian processes. Further research is needed to refine these correlations and enhance the understanding of sedimentary dynamics in polar settings. [ABSTRACT FROM AUTHOR]

The Ecca equivalent coal deposits in the Morupule, Mmamabula, and Mabesekwa coalfields exist within the Kalahari Karoo Basin of the Karoo Super Group. Only the Morupule coal has proved its potential for power generation; while, the utilization value of the Mmamabula and Mabesekwa coals is yet to be determined. The current study presents petrographical characteristics of the three seams from each coalfield. Reflected light microscopy combined with scanning electron microscopy was used in the study. The analyses revealed that the Morupule and Mabesekwa coals are rich in inertinite; while, the Mmamabula coal is rich in vitrinite. The vitrinite reflectance indicates that the coal rank stretches between high volatile bituminous B and high volatile bituminous A. The compositions of macerals and coal facies indicate variations in the depositional conditions for the three studied coalfields. The Morupule and Mabesekwa coals were accumulated in a terrestrial bedmont dry forest swamp through fluvial vegetation transportation; while, the Mmamabula coal was deposited in a limnic upper plain wet forest swamp through alluvial vegetation transportation. Hydrological conditions were rheotrophic except in the Mmamabula South, which had ombrotrophic conditions. Based on petrographic compositions, coals from the Mmamabula East, Mmamabula South, Morupule East Main, Morupule West Main and Morupule South would be suitable for carbonization, gasification and liquefaction processes. However, several challenges with coals from the Mmamabula South, Mabesekwa Seam B, Mabesekwa Seam C and Mabesekwa Seam E would be encountered during carbonization, gasification and liquefaction due to high ash content and inert semifusinite content. [ABSTRACT FROM AUTHOR]

Abstract Rare earth element (REE)-rich phosphorite in the Guizhou region mainly exists in the Doushantuo Formation and Gezhongwu Formation in early Cambrian strata, which are some of the important strata containing phosphorite resources in China. The early Cambrian Zhijin phosphorite in Guizhou Province, China, has high rare earth element and yttrium (REY) contents of up to 2500 ppm, with heavy REY (HREY) contents accounting for ~ 30% of the total REY contents. However, the specific controlling source and environment of phosphorite (especially the REEs in Zhijin phosphorite) are still unsolved. Through field geological investigations; mineralogical, geochemical, Sr–Nd isotope analyses; and tectonic characteristics, the material source, sedimentary environment and seawater dynamics of REEs in phosphorite are studied. It is considered that the REEs enriched in the Zhijin phosphorite are mainly affected by precipitation from hydrothermal fluid. Moreover, from the late Ediacaran to the early Cambrian, the depositional environment from the bottom to the top of the water tended to be hypoxic, and the activity of hot water fluid tended to be strong. The change in redox conditions is closely related to the rise and fall of sea level. Combined with the tectonic background, these results show that the weakly oxidized environment may be an important factor controlling the enrichment of REEs. The enrichment of REEs may be closely related to volcanic hydrothermal activity, later diagenesis and seawater dynamics.

Relevance. The need to study high-carbon deposits as potential sources of hydrocarbons and ore minerals that can significantly increase the mineral resource of Russia. In addition, the analysis of lithological and geochemical features and the reconstruction of the sedimentation conditions of the Kuonamka Formation make it possible to more accurately judge the nature of the Lower and Middle Cambrian paleobasin in the east of the Siberian Platform. Aim. To identify lithological and geochemical features of the composition and determine the sedimentation environment of the Kuonamka Formation. Object. High-carbon deposits of the Kuonamka Formation uncovered by exploration wells on the eastern margin of the Mun arch of the Siberian platform in the Kulenke river basin. Methods. Lithological description of core material; mineralogical and petrographic analysis; X-ray diffraction, X-ray fluorescence and microelement analysis; determination of the content of sulfur and iron forms by wet chemistry; scanning electron microscopy using X-ray spectral microprobe; analysis of petrochemical modules. Results. It was established that the Kuonamka Formation in the studied sections has a consistent structure of four well-defined lithological-stratigraphic horizons. The composition of the deposits is predominantly mixed and is determined by variations in three main mineral groups: clay, carbonate and siliceous, in addition organic matter. The paper demonstrates different forms of organic matter confirming the mixed algal-bacterial genesis of the biocenosis of the Kuonamka basin. The revealed lithological features and lithochemical data indicate the accumulation of high-carbon deposits at a considerable distance from the drift sources in the depression zone of the open sea basin with weak circulation of bottom waters in anoxic conditions. The geochemical euxinic environment was dominant in carbonate-siliceous muds. Sedimentation occurred during one major transgressive-regressive sedimentation cycle being a typical sequence of filling a uncompensated deep depression.

This first checklist of coastal marine fish inhabiting the Department of Atlántico (Colombian Caribbean) was compiled through an exhaustive review of published information, databases, other unpublished sources, and primary data. We recorded 272 fish species, of which twenty were first reported for this region. Carangidae, Lutjanidae, and Scombridae were the richest families, which together represent 14 % of the total number of species. According to the Red List of Marine Fishes of Colombia, 37 species show some degree of threat. Most species are demersal, associated with soft bottoms. However, a significant number of species were also found associated with hard substrates, suggesting that fish congregate around these less abundant substrates, as the coastline is mainly dominated by fine sediments. This study reveals that this region has higher fish richness than previously thought and highlights the need to carry out further studies to increase the knowledge of the ichthyofauna, framed in the environmental setting of the Department’s coastal zone and the anthropogenic influence on the group in question. Bet-ter knowledge of the richness of ichthyic species contributes indirectly to the improvement of current management plans for marine biodiversity conservation.

Purpose: This study is aimed at analyzing the spatial distribution of magnetic susceptibility and the content of potentially toxic elements (PTEs) in the surface layer of bottom sediments in the Vistula estuary (Gulf of Gdańsk, Poland) in relation to local sedimentary conditions. We also assessed the usefulness of magnetic susceptibility measurements to identify changes in sediment properties caused by anthropogenic factors. Materials and methods: Bottom sediments were collected along three transects using the Van Veen grab sampler. The following properties were determined: granulometric composition, organic matter and carbonate content, pH, electrical conductivity, and heavy metal content (Cd, Cr, Cu, Fe, Ni, Pb, and Zn). Specific (mass) magnetic susceptibility (χ) was measured using the MS2 Bartington® laboratory magnetic susceptibility meter. To characterize the conditions of the sedimentary environment in the study area, statistical analysis was performed on selected parameters of grain size distribution, such as mean grain diameter (Mz) and sorting (σ1) indices. Results and discussion: The research showed significant differences in the sedimentary environment (erosion vs. deposition processes) along the studied transects which were controlled by the wave regime, sea currents, and river water inflow. Open-water sediments were richer in organic matter and more saline than deltaic sediments, which in turn were characterized by higher pH and higher carbonate content. The highest mean total content of Pb, Cu, Ni, and Zn and the highest magnetic susceptibility (χ) were determined in open-water sediments, while the highest Fe and Cr values were obtained for deltaic sediments. Statistically significant differences between these sediments were found only for organic matter (LoI), Pb, Cu, and Cd content. Magnetic susceptibility showed a moderate correlation with Pb, Cu, Cd, and Zn (rs 0.4–0.6). Conclusion: PTE content and magnetic susceptibility of sediments showed a very high heterogeneity within the study area, depending mainly on the location (delta vs. open waters), grain size composition, and organic matter content. Our results demonstrated that magnetic susceptibility analysis is an easy method that can be used to complement the identification of technogenic changes in the marine environment. [ABSTRACT FROM AUTHOR]

The sedimentary dynamics and geological evolution of the Naples canyons during the Late Quaternary have been studied based on sedimentological and seismo-stratigraphic data. Several factors, including the sedimentary environments, tectonic setting, and volcanic eruptions, have controlled the geological evolution of the coastal and marine areas of the Bay of Naples. The main data and methods include the sedimentological data analysis, the seismo-stratigraphic techniques applied in the geological interpretation of seismic profiles, and the integrated analysis of core data that were previously published. The formation of the Dohrn canyon is controlled by fluvial processes, active in correspondence with the palaeo-Schiazzano River system and by the main eruptive events involving the submarine portion of Naples Bay, including the Campanian Ignimbrite (CI; 39 ky B.P.) and the Neapolitan Yellow Tuff (NYT; 15 ky B.P.). The formation of the Magnaghi canyon is controlled by erosional processes on the continental slope of Procida Island, which was active during the last eruptive phases of the island (Solchiaro Formation; 18 ky B.P.), triggering high rates of volcaniclastic supply. [ABSTRACT FROM AUTHOR]

Particle morphology is an important feature of sediments that reflects their transport history and depositional environment. In this study, we used dynamic image analysis (DIA) to measure the size and shape of beach sediments on the east and west coasts of Hainan Island in South China Sea. DIA is a fast and accurate method that can capture and analyze a large number of sediment particles in real-time. We extracted morphological descriptors of each particle, such as equivalent diameter, sphericity, aspect ratio and symmetry, and their distributions based on volume and number. We performed multivariate analysis on the particle morphological data, including alpha diversity, statistical analysis and fingerprint techniques. We found that the Shannon index, calculated by the number distribution of sediment particle morphology, can effectively discriminate between the two sites, reflecting different sediment sources, transport processes and depositional conditions. We also established a composite fingerprint based on seven morphological parameters and diversity indices, which can accurately distinguish between aeolian and hydraulic sedimentary environments. Our study demonstrates the potential application of DIA in identifying sedimentary environments and establishing sediment fingerprints. This can help us understand the sediment transport processes and depositional mechanisms in coastal areas. [ABSTRACT FROM AUTHOR]

Although the amount of oil and gas reserves and the reservoir properties in the East China Sea Shelf Basin (ECSSB) indicate good prospects for oil and gas exploration in the Mesozoic strata, there has not yet been a significant breakthrough in oil and gas production. An important reason is that there are few detailed studies on the sedimentary paleogeography of the ECSSB which make it difficult to predict the distribution of sand bodies. In this paper, well-core observations, thin-section identifications, electron probe microanalysis, trace elements analysis and seismic interpretations were synthetically applied to study the sedimentary environments and the tectonic setting of the Upper Cretaceous in the southern ECSSB. In the Oujiang Sag, red mudstones and pyroclastic rocks were deposited, accompanied by wedged, chaotic pro-grading reflections in the seismic profile, indicating a volcano-alluvial fan sedimentary system. Abundant sedimentary structures including double-mud drapes, asymmetric herringbone cross-beddings and burrows, such as Planolites and Skolithos, were developed in the Minjiang Sag, typically indicating a high-energy tidal environment. The autogenetic glauconites in situ and the fossil Tintinnid also indicate a shallow marine environment. The resulting sedimentary characteristics are in accordance with the littoral facies revealed by the seismic reflections in the Minjiang Sag. Moreover, volcanic conduit facies, effusive facies, and pyroclastic facies were also recognized in the seismic profile in the Minjiang Sag. Therefore, it was presumed that subaqueous volcanic eruptions occurred in the Minjiang Sag. In the Keelung Sag, the littoral facies were dominant. The tectonic setting of the Upper Cretaceous in the southern ECSSB is the transitional arc accompanied by large-scale volcanic activities. In conclusion, the volcano-alluvial fan sedimentary system was developed in the Oujiang Sag and volcano-littoral sedimentary system was developed from the Minjiang Sag to the Keelung Sag. This study is intended to promote the understanding of the sedimentary paleogeography of the Upper Cretaceous in the southern ECSSB and to provide help in oil and gas exploration. [ABSTRACT FROM AUTHOR]

Copyright of Caldasia is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To better understand the depositional constraints on the fingerprint characteristics of methane isotopes, we present a set of carbon/hydrogen isotopic data for CH4, CO2, pore water, carbonate, and total organic carbon along a 70‐m sedimentary core. The sedimentary facies (Units I, II, and III from upper to bottom) suggested depositional environments of the present estuary, shallow marine, and floodplain‐estuary. Calculations suggested that around 86% of methane was produced through the CO2 reduction pathway. In this pathway, the hydrogen in CH4 is from ambient water, while the carbon is from dissolved inorganic carbon. Correspondingly, our study showed that the values of δDCH4 displayed similar trends with those of δDH2O and Cl− concentrations along the depth profiles. The low δDCH4 below 44.5 m corresponded to low δDH2O and low salinity during the cold and low‐sea‐level period. The values of δ13CCH4 generally synchronously changed with those of δ13CCO2. The variation trends of δ13CCH4 and δ13CCO2 were the same with δ13Ccarbonate from 10 to 70 m depth but decoupled above 10 m. The values of δ13CCH4 in Units II and III were correlated with the δ13Ccarbonates, which is related to the sedimentary processes. But decoupling of low values of δ13CCH4 and δ13CCO2 from δ13Ccarbonates in Unit I may be related to preferential microbial consumption of labile compounds with light carbon isotopic compositions, such as lipids. In short, the variations of δ13CCH4 and δDCH4 were largely related to the sedimentary process, which controlled the isotopic compositions of both water and carbonate. Plain Language Summary: As an important greenhouse gas, methane (CH4) contributes more to global warming than the same mole's carbon dioxide (CO2). The methane isotopic composition is widely used to trace sources. Coastal sediments, recording the rise and stabilization of the global sea level since the Last Glacial Maximum, host enormous volumes of CH4. Of interest is whether the depositional process could impact methane isotopic signatures, adding uncertainty to the traceability. We conducted analyses including C/H isotopic data of CH4, CO2, porewater, carbonates, and total organic carbon along a 70‐m sedimentary core from Hangzhou Bay, China. Calculations suggested that about 86% of methane was produced through the CO2 reduction pathway. In this pathway, the hydrogen in CH4 is derived from ambient water, while the carbon is from CO2, which was isotopically in equilibrium with carbonate. Our results suggested that sedimentary processes are the primary abiotic factors affecting the variations of the stable carbon and hydrogen isotopic compositions of biogenic CH4 from coastal sediment. Key Points: Higher than 80% of biogenic methane along the sediment core was produced through the CO2 reduction pathwayC and H of biogenic CH4 from ambient CO2 and H2 are isotopically in equilibrium with ambient carbonate and water, respectivelyThe sedimentary process is one of the primary abiotic factors affecting the variations of δ13CCH4 and δDCH4 from coastal sediment [ABSTRACT FROM AUTHOR]

Kaštela Bay was taken as a model to study sedimentation processes using the vertical sediment profiles of 137Cs massic activities. The aim was to distinguish the sedimentation conditions in different parts of the Bay and to partly determine the pathways of terrigenous input into the Bay. The purpose was to demonstrate that 137Cs profiles are applicable in differentiating sedimentation processes. It was found that mostly continuous, undisturbed sedimentation takes place in the central and south parts of the Bay; the sedimentation conditions in the west part of the Bay are more complicated. The west part is characterised by the extremely slow sedimentation of the coarse-grained sediment or even by erosion and selective resuspension of the fine-grained particles followed by resedimentation in other parts of the Bay. It was also observed that the upper 10 cm of the sediment is the most exposed to homogenisation. The strong influence of the Jadro River and anthropogenic activities in the east part of the Bay are reflected in the higher 137Cs activities, strong sediment mixing, and increased sediment input. This study shows that the 137Cs profiles can provide comprehensive insights for the whole study region when a sophisticated sampling layout is deployed. The results of the study are applicable to other aquatic environments with comparable processes and sedimentary environments. [ABSTRACT FROM AUTHOR]

Members of candidate Asgardarchaeota superphylum appear to share numerous eukaryotic-like attributes thus being broadly explored for their relevance to eukaryogenesis. On the contrast, the ecological roles of Asgard archaea remains understudied. Asgard archaea have been frequently associated to low-oxygen aquatic sedimentary environments worldwide spanning a broad but not extreme salinity range. To date, the available information on diversity and potential biogeochemical roles of Asgardarchaeota mostly sourced from marine habitats and to a much lesser extend from true saline environments (i.e., > 3% w/v total salinity). Here, we provide an overview on diversity and ecological implications of Asgard archaea distributed across saline environments and briefly explore their metagenome-resolved potential for osmoadaptation. Loki-, Thor- and Heimdallarchaeota are the dominant Asgard clades in saline habitats where they might employ anaerobic/microaerophilic organic matter degradation and autotrophic carbon fixation. Homologs of primary solute uptake ABC transporters seemingly prevail in Thorarchaeota, whereas those putatively involved in trehalose and ectoine biosynthesis were mostly inferred in Lokiarchaeota. We speculate that Asgardarchaeota might adopt compatible solute-accumulating (‘salt-out’) strategy as response to salt stress. Our current understanding on the distribution, ecology and salt-adaptive strategies of Asgardarchaeota in saline environments are, however, limited by insufficient sampling and incompleteness of the available metagenome-assembled genomes. Extensive sampling combined with ‘omics’- and cultivation-based approaches seem, therefore, crucial to gain deeper knowledge on this particularly intriguing archaeal lineage. [ABSTRACT FROM AUTHOR]

The sedimentary dynamics and geological evolution of the Naples canyons during the Late Quaternary have been studied based on sedimentological and seismo-stratigraphic data. Several factors, including the sedimentary environments, tectonic setting, and volcanic eruptions, have controlled the geological evolution of the coastal and marine areas of the Bay of Naples. The main data and methods include the sedimentological data analysis, the seismo-stratigraphic techniques applied in the geological interpretation of seismic profiles, and the integrated analysis of core data that were previously published. The formation of the Dohrn canyon is controlled by fluvial processes, active in correspondence with the palaeo-Schiazzano River system and by the main eruptive events involving the submarine portion of Naples Bay, including the Campanian Ignimbrite (CI; 39 ky B.P.) and the Neapolitan Yellow Tuff (NYT; 15 ky B.P.). The formation of the Magnaghi canyon is controlled by erosional processes on the continental slope of Procida Island, which was active during the last eruptive phases of the island (Solchiaro Formation; 18 ky B.P.), triggering high rates of volcaniclastic supply.

The composition and depositional environments of the Tithonian(?)–Berriasian deposits in the Tonas River basin (Central Crimea) are considered. The paper describes the carbonate rock association represented by various types of limestones, breccias, calcareous clays, and marls. Microfacies types of rocks in thin sections are comparable with the standard microfacies formed on the slopes and foothill of carbonate basins. A fault-controlled distally steepened ramp model has been proposed to interpret this depositional environment. Microfacies types of the calcibreccia lithoclasts confirm the gravitational transport of debris from the inner parts of the ramp, thrombolite reefs included. Sections with similar succession are known in the Swiss Alps. [ABSTRACT FROM AUTHOR]

The interconnections between hydrodynamics, coastal sediments, and ecosystem distribution were analysed for a ~250 km strip on the northern Mexican Caribbean coast. Ecosystems were related to the prevailing and extreme hydrodynamic conditions of two contrasting coastal environments in the study area: Cancun and Puerto Morelos. The results show that the northern Mexican Caribbean coast has fine and medium sands, with grain sizes decreasing generally, from north of Cancun towards the south of the region. Artificial beach nourishments in Cancun have affected the grain size distribution there. On beaches with no reef protection, larger grain sizes (D50 > 0.46 mm) are noted. These beaches are subject to a wide range of wave-induced currents (0.01–0.20 m/s) and have steeper coastal profiles, where sediments, macroalgae and dune-mangrove systems predominate. The coastline with the greatest amount of built infrastructure coincides with beaches unprotected by seagrass beds and coral reefs. Where islands or coral reefs offer protection through less intense hydrodynamic conditions, the beaches have flatter profiles, the dry beach is narrow, current velocities are low (~0.01–0.05 m/s) and sediments are finer (D50 < 0.36 mm). The results offer a science-based description of the interactions between physical processes and the role played by land uses for other tropical coastal ecosystems. [ABSTRACT FROM AUTHOR]

To maintain a stable freshwater supply for sustainable economic activity in coastal areas in light of anticipated global climate change, it is important to understand the controlling factors and variability of past hydrologic behavior. In this study, we tested the grain size variability recorded in coastal sediments from Yeosu, on the southern coast of Korea, as an indicator of freshwater input change. We found a ca. 7 m sedimentary sequence (Stage 2) between lower fluvial to coastal marsh (Stage 1) and upper coastal marsh (Stage 3) deposits, which we infer was deposited in the inner bay at a water depth between ca. 10 and 2 m, over the time periods between 1.2 and 7.7 cal kyr BP. The variability in grain sizes corresponded to the low-resolution local freshwater input index in the Beolgyo area, providing a more detailed precipitation fluctuation record. The long-term variations in grain size was similar to that of the Asian summer monsoon fluctuation during the middle to late Holocene. Significant fluctuation at multicentennial time scales superimposed on the long-term variation clearly indicated intensified freshwater input periods (e.g., at 2.5, 3.0, 5.2, 6.3, and 7.7 cal kyr BP). These hydrologic changes in the study area appear to be linked to past El Niño-Southern Oscillation (ENSO) activity, such that intensified freshwater input occurred during stronger ENSO activity. Among these climatic shifts, severe rainfall events characterized by sand layers (e.g., at 7.7 and 2.5 cal kyr BP) can be used as isochronous sedimentary layers on the southern coast of Korea. [ABSTRACT FROM AUTHOR]

The fine-grained rocks in the Paleogene Shahejie Formation in Nanpu Sag, Huanghua Depression, Bohai Bay Basin, are extremely important source rocks. These Paleogene rocks are mainly subdivided into organic-rich black shale and gray mudstone. The average total organic carbon contents of the shale and mudstone are 11.5 wt.% and 8.4 wt.%, respectively. The average hydrocarbon (HC)-generating potentials (which is equal to the sum of free hydrocarbons (S1) and potential hydrocarbons (S2)) of the shale and mudstone are 39.3 mg HC/g rock and 28.5 mg HC/g rock, respectively, with mean vitrinite reflectance values of 0.82% and 0.81%, respectively. The higher abundance of organic matter in the shale than in the mudstone is due mainly to paleoenvironmental differences. The chemical index of alteration values and Na/Al ratios reveal a warm and humid climate during shale deposition and a cold and dry climate during mudstone deposition. The biologically derived Ba and Ba/Al ratios indicate high productivity in both the shale and mudstone, with relatively low productivity in the shale. The shale formed in fresh to brackish water, whereas the mudstone was deposited in fresh water, with the former having a higher salinity. Compared with the shale, the mudstone underwent higher detrital input, exhibiting higher Si/Al and Ti/Al ratios. Shale deposition was more dysoxic than mudstone deposition. The organic matter enrichment of the shale sediments was controlled mainly by reducing conditions followed by moderate-to-high productivity, which was promoted by a warm and humid climate and salinity stratification. The organic matter enrichment of the mudstone was less than that of the shale and was controlled by relatively oxic conditions. [ABSTRACT FROM AUTHOR]

Copyright of Anuario do Instituto de Geociencias is the property of Universidade Federal do Rio de Janeiro, Instituto de Geociencias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, the Journal of Palaeogeography (Chinese Edition and English Edition) continually received manuscripts, in which some authors are from China and some are from Pakistan, Lithuania, Morocco, South Africa, etc. The authors of these manuscripts, according to the viewpoint and method of Miall's paper (1985), selected rocks from each bed in the clastic sections of their study areas and induced some rock types, such as conglomerates, sandstones and fine-grained stones, and considered them as lithofacies. It does not conform to the definition of lithofacies. I wrote some papers, i.e., Feng (2018, 2019, 2020), to point out the problems and hope that the authors worldwide, especially Chinese authors, will not continually cite, spread and follow Miall's paper (1985) viewpoint and method blindly. Prof. Miall is the first person who considered rocks (in fact, the sediments) as lithofacies and proposed a facies analysis method. His viewpoint and facies analysis method confused the definition of facies and facies analysis method. My current paper is a special article to discuss the principal problems of Miall's paper (1985), i.e., he considered the sediments as lithofacies and utilized lithofacies to analyze facies, but not to discuss the contributions and less strictness of architectural elements of his paper. Here, I have to declare that the facies in my current paper is the facies of sedimentary petrology, but not of other geological disciplines, such as igneous petrology, metamorphic petrology, palaeontology, stratigraphy, geophysics, geochemistry. Certainly, the definitions of facies and lithofacies are controversial. My current paper will adhere to the policy of "A hundred flowers blossom and a hundred schools of thought contend". I hope that through academic discussions, contends and geological practice, these problems will be solved gradually. [ABSTRACT FROM AUTHOR]

The current study hypothesizes that reproducing sediment units that might belong to areas difficult to reach, sample, and attest is experimentally possible. The research aims to employ available sediment samples named source soils that can easily approach and sample to mix, simulate, and produce the (non-available) sedimentary units named Target Sediment Units (TSU). The particle size distribution (PSD) percentages are essentially used in the mixture procedure to construct the non-available (target) units (TSU). Several sedimentary units were targeted, designed, and simulated; They include marsh, bay mud, and natural levee sediment units selected from the eastern Basrah side at the lower Mesopotamian plain, southern Iraq. The matching between particle size distribution (PSD) curves of simulated sediment units (SSU) and target sediment unit (TSU) was verified by applying a developed slope proximity ratio. For the three tested sediment units (marsh, buy mud, and natural levee), the ratios of slope proximity were 1.0, 0.93, and 0.99, respectively, which are well matched. For the mineralogy, the consistency limits were used as a proxy. The Casagrande plasticity chart was modified to reveal two empirical functions linking the plasticity indices to the clay mineral groups. The two predictions are reliable means to proxy the mineralogy of the fine-grained sediments. Reconstructing procedure allows the non-available sediment samples to be practically presented and it better characterizes the sediment for forensic geoscience applications; for instance, engineering geology and sedimentology applications concerning with studies of the physical and mechanical behaviors of sediments and the depositional conditions interpretations, respectively. [ABSTRACT FROM AUTHOR]

A large number of siderites have been found in the Lopingian (Late Permian) coal-bearing series in western Guizhou, which occurs in various microscopic morphologies and has potential insights into the sedimentary and diagenetic environments. An integrated set of analyses, such as microscopic observation; X-ray diffraction; whole-rock major and trace element, carbon, and oxygen isotope; and in situ major and trace element, has been carried out to unravel the genetic mechanism of the siderites and their environmental implications. According to the microscopic morphology, the siderites can be generally divided into three types and six subtypes, including gelatinous siderites (I), microcrystal-silty siderite [II; microlite siderites (II1), powder crystal siderites (II2)], and spheroidal siderite [III, petal-like siderite (III1), radiating fibrous siderite (III2) and concentric siderite (III3)]. Whole-rock geochemical results show that the iron source for the formation of the siderites was mainly from extensive weathering of the Emeishan high-titanium basalts in hot climate conditions. The carbon and oxygen isotopic results indicate that the origin of CO2 in type I siderites is derived from the dehydroxylation of organic matter. The CO2 in types II1 and II2 siderites is mainly derived from deposited organic matter and marine carbonate rocks, respectively. The CO2 source of type III siderites is sedimentary organic matter and marine carbonate rocks and is affected by different fluids during diagenesis. The whole-rock and in situ geochemical characteristics further point to that type I siderites were formed in the synsedimentary period most strongly affected by seawater. Redox proxies, such as V/Sc, V/(V+Ni), and δ Ce, constrained their formation in a stable and weakly reduced condition. Type II siderites could have been developed in saltwater. Among them, type II1 siderites were formed in the early diagenetic stage, whereas type II2 siderites originated from recrystallization of type II1 siderites and accompanied by metasomatism with calcites under diagenetic fluids of weak reduction to weak oxidation conditions. Type III siderites were formed under the influence of multistage diagenetic fluids. Among them, type III1 siderites formed by the growth of powder crystal siderites (II2) under diagenetic fluids with a weak reducing condition. Type III2 siderites formed by growth around microlite siderites under weak reducing diagenetic fluids. Type III3 siderites formed by concentric growth in diagenetic fluids with weak reduction to weak oxidation conditions and relatively active conditions.

Bacalar Lake is characterized by a high saturation of calcium, bicarbonate, sulfate and silicate in its water and these conditions harbor a microbialite community. To explore the nematode fauna, associated with microbialites, 11 sites along the lake were selected. The collected microbialites were carefully dissolved and nematodes extracted manually. Nematodes were represented by 2 classes, 10 orders, 17 families, and 22 genera. Dorylaimidae and Xyalidae were the richest in genera (3 each), while the family Selachinematidae was represented by Choanolaimus, which is first reported in epicontinental systems. Dichromadora (48), Epitobrilus (31), Dorylaimus (30), Ischiodorylaimus (24), Belondira (13), Aphanolaimus (11) and Monhystera (10) were the most abundant genera. All Nematode's freshwater feeding types were present, but deposit feeders (DF) were observed with 35%. We concluded that nematodes are an important component of the metazoan fauna in microbialites from Bacalar Lake, with a higher diversity than reported in other lakes and marine environments. Nematodes can take advantage of the micro-spaced texture of microbialites and function as bioturbators, as well as escape predation, taking advantage of available food, which is reflected in the structure of nematode feeding types. More research on the interaction of microbialites-nematodes is necessary to understand their role in this poorly known environment. [ABSTRACT FROM AUTHOR]

Statistical manipulation of large radiometric data sets (big data) is increasingly applied to those grand challenges in archaeology that relate to past human‐behavioural dynamics and includes frequency analysis of radiocarbon ages (summed probability distributions [SPDs]). Australian SPD studies use the radiocarbon database "AustArch" to examine regional‐ and continental‐scale demographic change. We review Australian studies, focussing on sampling bias and taphonomic bias, finding that (i) time‐averaged radiometric data cannot simply be correlated across regions, and (ii) sedimentology imposes genuine constraints upon what can be known. Internationally, flaws in SPD use occur in all main research phases, and most importantly, at the initial phase of defining research questions, logic and general approach. Major problems stem from not planning to obtain a sound understanding of the variability of past sedimentary environments, potential occupation sites and site formation processes. Thus, cultural inferences are too often made from archaeological data without due consideration of the natural processes that may explain the data. Highlighting exemplar studies, we present practical approaches to improve SPD use for exploring changes in demography, aimed at reducing uncertainties and reconnecting archaeological, chronological, geological and sedimentary data. Most important is to increase understanding of physical processes and their control on the archaeological record. [ABSTRACT FROM AUTHOR]

The interconnections between hydrodynamics, coastal sediments, and ecosystem distribution were analysed for a ~250 km strip on the northern Mexican Caribbean coast. Ecosystems were related to the prevailing and extreme hydrodynamic conditions of two contrasting coastal environments in the study area: Cancun and Puerto Morelos. The results show that the northern Mexican Caribbean coast has fine and medium sands, with grain sizes decreasing generally, from north of Cancun towards the south of the region. Artificial beach nourishments in Cancun have affected the grain size distribution there. On beaches with no reef protection, larger grain sizes (D50 > 0.46 mm) are noted. These beaches are subject to a wide range of wave-induced currents (0.01–0.20 m/s) and have steeper coastal profiles, where sediments, macroalgae and dune-mangrove systems predominate. The coastline with the greatest amount of built infrastructure coincides with beaches unprotected by seagrass beds and coral reefs. Where islands or coral reefs offer protection through less intense hydrodynamic conditions, the beaches have flatter profiles, the dry beach is narrow, current velocities are low (~0.01–0.05 m/s) and sediments are finer (D50 < 0.36 mm). The results offer a science-based description of the interactions between physical processes and the role played by land uses for other tropical coastal ecosystems.

Geochemical studies on Kuroyu hot springs in Ohta-ku area of Tokyo were carried out to elucidate their characteristics, especially focused on organic components including humic acid, together with source organisms and sedimentary environments. Kuroyu hot spring qualities are mainly sodium-hydrogen carbonate or sodium-hydrogen carbonate/chloride. These hot springs may be formed by contribution levels of granitic rocks and ion exchange reaction of montmorillonite. The inverse correlation between Log-transparency and humic acid contents showed that color levels of Kuroyu hot springs are attributed to humic acid contents. Saturated fatty acids were mainly composed of short-chain n-alkanoic acid (C12-C18) with small amounts of long-chain n-alkanoic acids (C20-C34) and branched acids (iso- and anteiso- C13-C17). Unusually, considerable amounts of n-alkenoic acids (n-C16:1(9), carbon chain length : number of unsaturation (double bond position), n-C16 : 1(8?), n-C16 : 1(7), n-C16 : 1(5), n-C18 : 1(9), n-C18 : 1(7)) were found in ethyl acetate extracts and pyrolysis-tetramethylammniumhydroxide-methylation products (Py-TMAH-Me) of humic acid. Major sterols in ethyl acetate extracts were all cholesterol with small amounts of 24-methylcholesterol and 24-ethylcholesterol and others. Organic components in Kuroyu hot springs are mainly originated from algae including plankton with small contribution of vascular plants and bacteria. The absence of polyunsaturated fatty acids are ascribed to the degradation loss in the sedimentary environments. Well depths (30-120 m) showed that sedimentary environments are shallow Paleo Tokyo Bay of Shimousa Group and marine land shelf slope of upper Kazusa Group in ages 0.5-1 Ma. [ABSTRACT FROM AUTHOR]

From the viewpoint of origins of soft-sediment deformation structures (SSDS), 7 papers (Ito et al., 2016; Jiang et al., 2016; Lunina and Gladkov, 2016; Moretti et al., 2016; Rana et al., 2016; Rodríguez-Pascua et al., 2016; Wheatley et al., 2016) selected from the special issue of “The environmental significance of soft-sediment deformation” of the Sedimentary Geology 344 (2016) were reviewed. (1) The first paper (according to the published order) by Moretti et al. is a general review and introduction of this special issue. This special issue has made an important contribution to the study of sedimentary environments. (2) The fourth paper by Rodríguez-Pascua et al. is an excellent case study. All evidence of earthquake in this paper is reliable. The old Roman City (adjacent to Madrid, the capital of Spain) was definitely destroyed by an earthquake. This paper solved the problem that the archaeologists have not solved yet. (3) The 19th paper by Rana et al. is another excellent case study. It demonstrated that SSDS in the youngest modern sediments in the seismically active area, i.e., the Alaknanda Valley, Garhwal Himalaya, India, are of non-seismic origin, but with typically sedimentary origin. All evidence of sedimentary origin of SSDS in the study area is reliable. (4) The second paper by Lunina and Gladkov stated that SSDS (mainly clastic dikes) in epicentral areas of the recent earthquakes in southern Siberia were originated by earthquakes and that the clastic dikes are the most reliable indicators in the epicentral areas of earthquakes. This conclusion is right. However, it is not accurate to consider all clastic injections as “in-situ earthquake structures” in anywhere, because the clastic injections are with multiple origins. (5) The third paper by Wheatley et al. comprehensively stated the clastic pipes of the Jurassic in the Colorado Plateau, USA. However, the principal origin of the clastic pipes (columns) was possibly not originated by “palaeoseismic controls”, but by “tectonic controls” or “tectonic uplifts”. (6) The 10th paper by Jiang et al. proposed that 6 types of SSDS of the Lixian Section in eastern Tibetan Plateau, i.e., in a tectonically and seismically active area, were originated by earthquakes. However, the evidence of seismic origin is not sufficient. Therefore, the origins of SSDS in the Lixian Section are worthy to be further discussed. (7) The “injectites” and “extrudites” in a Late Pliocene basin on the Boso Peninsula, Japan, from the 24th paper by Ito et al., are non-SSDS and their origin is unreliable. The above viewpoints may be inappropriate. Criticisms and corrections are welcome. This paper is not only the author's brief review on 7 papers selected from the special issue of the Sedimentary Geology 344 (2016), but also an invitation to geologists worldwide to write papers for a new special issue of “The origins of SSDS” of the Journal of Palaeogeography which is planned to be published in 2018.

The microbial structures of various genesis are rock-forming components in limestones of the Kizelovian regional substage (the Tournaisian stage) on the Middle Urals eastern slope. Comprehensive petrographic analysis of distinct grains allowed to reconstruct the carbonate platform depositional environments. Microbial structures in this study include: 1) calcitarcha (calcite “spheres” and similar sub-circular microfossils), 2) bioclasts of calcareous green algae, 3) bioclasts of calcified cyanobacteria/calcimicrobes (or calcibionts), 4) most peloids and traces of grains micritization, 5) oncolites (oncoids) and intraclasts of other microbialites. Environmental indicators evidence that sedimentation throughout the Kizelovian time was carried out within the upper subtidal photic zone, in conditions of high salinity and limited water circulation. A distribution of microfacies shows that the basin depth at an average corresponded to the normal wave basis. Microbiota taxonomic composition and bottom configuration features largely determined differences in sediment deposition characteristics. Some carbonate sedimentology terminologic issues are also discussed in this article.

The evolution of incised valleys is an important area of research due to the invaluable data it provides on sea‐level variations and depositional environments. In this article the sedimentary evolution of the Ría de Ferrol (north‐west Spain) from the Last Glacial Maximum to the present is reconstructed using a multidisciplinary approach, combining seismic and sedimentary facies, and supported by radiocarbon data and geochemical proxies to distinguish the elements of sedimentary architecture within the ria infill. The main objectives are: (i) to analyse the ria environment as a type of incised valley to evaluate the response of the system to the different drivers; (ii) to investigate the major controlling factors; and (iii) to explore the differentiation between rias and estuaries. As a consequence of the sea‐level rise subsequent to the Last Glacial Maximum (ca 20 kyr bp), an extensive basin, drained by a braided palaeoriver, evolved into a tide‐dominated estuary and finally into a ria environment. Late Pleistocene and Holocene high‐frequency sea‐level variations were major factors that modulated the type of depositional environments and their evolution. Another major modulating factor was the antecedent morphology of the ria, with a rock‐incised narrow channel in the middle of the basin (the Ferrol Strait), which influenced the evolution of the ria as it became flooded during Holocene transgression. The strait acted as a rock‐bounded 'tidal inlet' enhancing the tidal erosion and deposition at both ends, i.e. with an ebb‐tidal delta in the outer sector and tidal sandbanks in the inner sector. The final step in the evolution of the incised valley into the modern‐defined ria system was driven by the last relative sea‐level rise (after 4 kyr bp) when the river mouths retreated landward and a single palaeoriver was converted into minor rivers and streams with scattered mouths in an extensive coastal area. [ABSTRACT FROM AUTHOR]

• Alluvial-fan to delta-coastal environments in an initial stage of basin-fill. • Depositional breaks occurred in the late Meso- to Neoproterozoic caused by uplifts. • Depocenter migrated from the north to the south in the late Meso- to Neoproterozoic. • Detrital zircon ages in the Mesoproterozoic and Paleozoic show variable provenances. • The North China Craton was involved in the assembly of the Rodinia Supercontinent. The North China Craton (NCC) is thought to experience multi-stage extensional events after the breakup of the Columbia (Nuna) Supercontinent, and even during the assembly of the Rodinia Supercontinent. In recent years, volcanic and detrital zircon U-Pb dating ages provided new insights into the Mesoproterozoic to Neoproterozoic tectonic framework in the NCC. As the Mesoproterozoic Xiong'er Group in the southern NCC is regarded as the oldest volcanic-sedimentary succession after the final amalgamation of the NCC, we reviewed the sedimentary environments and provenances of Mesoproterozoic to Neoproterozoic sedimentary sequences above the strata in order to understand tectono-sedimentary evolution of the southern NCC during this period. The early Mesoproterozoic sedimentary rocks were deposited in alluvial-fan to fluvial and (fan-) delta-coastal environments suggesting an initial stage of basin development. Fine-grained clastic sedimentary rocks interlayered with carbonate deposition formed on the southern NCC later, and implied a broad subsidence before ca. 1611 Ma. After that, depositional breaks caused by regional tectonic uplifts led to different sedimentary sequences and lateral migration of the depocenter from the north to the south (to the current co-ordinates). The unconformably overlying sedimentary rocks in the north of the southern NCC were deposited in restricted marine basins during late Mesoproterozoic to Neoproterozoic as a whole. However, the enlargement of shallow-marine shelf led to the thick accumulation of carbonates in the southernmost NCC characterized by a deepening-upward trend from the late Mesoproterozoic sequence. The Neoproterozoic sedimentary sequence is typified by sharp increasing terrigenous supplies and frequent changes in environment, and could be deposited in a tectonically active basin in consideration of its close association with volcanism. Detrital zircon grains from the oldest clastic sequence (i.e., the Bingmagou Formation) overlying the Xiong'er volcanic-sedimentary rocks and from the earliest Paleozoic sedimentary rocks (i.e., the Xinji Formation) are used to track changes of provenances. Detrital zircon grains from the Bingmagou Formation display two dominant age peaks at ca. 1850 and 2500 Ma and three secondary peaks at ca. 2100, 2350 and 2700 Ma. In contrast, detrital zircon grains from the Xinji Formation have three major age peaks at ca. 1850, 2200 and 2500 Ma and three subordinate populations of 950, 1100 and 1450 Ma. In combination with the uplifts during the Mesoproterozoic to Neoproterozoic, Neoproterozoic magmatism, and a large amount of detrital zircon derived from Rodinia-related orogenesis in the southern NCC, it is very likely that the major changes of basin configuration could be related to significant tectonic readjustment along with the evolution of the Rodinia Supercontinent. [ABSTRACT FROM AUTHOR]

The Appalachian landscape provides an excellent opportunity to examine an environment that promotes sediment subsidence, accumulation and possible preservation: mantled karst. Mantled karst exists along the Blue Ridge-Great Valley margin from south-central Pennsylvania to central Virginia. Topographically, the mantled karst contains low-relief irregular topography with abundant surface depressions, some of which contain ponds, and in places lacks continual surface drainage and springs. Sand and gravel quarries along the valley margin expose predominantly stream flow, hyperconcentrated flow, debris flow and hillslope (colluvial) deposits that mantle karstic Paleozoic bedrock and carbonate residuum. Unconformable and sometimes erosive contacts between carbonate residuum and clastic sediments, and soft-sediment deformation features have been observed within exposures suggesting subsidence into accumulation and/or preservation space created by geochemical dissolution and collapse that continues today. The likelihood of long-term survival in the geological record is dependent upon the relationship between the subsiding sediment and geomorphic base level. The Blue Ridge-Great Valley mantled karst likely contains both short-term accumulation space that is closer to geomorphic base level, thus more prone to removal by fluvial processes, and preservation space, which occurs well below geomorphic base level, where sedimentary sequences may be stored for prolonged periods of time. Ultimately, both accumulation and preservation spaces can provide insight into depositional processes, landscapes and possibly paleoenvironmental conditions, but the geologic record becomes more distorted and fragmented further back into deep time and as this landscape evolves into the future. [ABSTRACT FROM AUTHOR]

There are many reservoirs with low porosity and low permeability in the world, and many large oilfields have been found in these reservoirs. Unlike conventional reservoirs, the genesis of low-porosity and low-permeability reservoirs and the controls of relatively high-porosity and high-permeability zones are still unclear. This study takes the Chang10 1 reservoir sandstones of the Shanbei area in the Ordos Basin, China, a typical low-porosity and low-permeability, as an example. Chang10 1 sandstones are fine-grained to medium-grained, moderately to well sorted arkose and lithic arkose deposited in a delta plain environment. It is a typical low porosity and low permeability reservoir with an average porosity of 10.21% and an average permeability of 2.88 mD. Pore types mainly include primary intergranular pores and secondary dissolved pores. The main controls on the reservoirs are the sedimentary environment and diagenesis. The sedimentary environment determines the initial properties of the reservoir sandstones, including the material composition and texture that determine the primary porosity and permeability. Diagenesis further transforms the reservoir quality to develop heterogeneity in the porosity and permeability. The reservoir sandstones have undergone complex diagenetic processes and are currently in stage A of mesodiagenesis. Compaction accounts for the major reduction of the primary porosity of the sandstones. Different types of cementation have both positive and negative influences on reservoir quality. Carbonate cementation, quartz overgrowths and some authigenic clay cementation(i.e., I/S and illite) are major pore-filling components, that reduce the reservoir quality. An appropriate amount of chlorite resists compaction and prevents quartz overgrowth, but excessive chlorite coatings fill the pores and block the pore throats. The laumontite cement is not only resistant to compaction but also easily dissolved to form a large number of effective secondary pores. The dissolution of feldspar and rock fragments plays a role in contributing to connecting the isolated intergranular pores and increasing the secondary pores. Relatively high porosity and high permeability zones are deposited in high-energy environment, mainly delta plain distributary channel sandstones with more detrital quartz, fewer rock fragments and coarser grains than other sandstones, were deposited in high-energy environment. There is weaker compaction and less or no carbonate cement, with the preservation of the primary pores by chlorite coatings and an increase in the pores by the dissolution of laumontite cement. • Basic characteristics of the Chang 10 1 reservoir were analyzed. • Types and genesis of diagenesis were detailed exposited. • Sedimentary environment control the innate inheritance of the reservoir. • Diagenesis transforms the quality of reservoirs seriously. • A general mode of relationship between sedimentology and diagenesis were proposed. [ABSTRACT FROM AUTHOR]

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Research into the surface soil pollen found within different sediments constitutes one important part of modern palynological analysis; however, such studies have not been carried out in the arid regions of Asia. In order to determine the main characteristics of the pollen assemblages of different sediments, 26 surface pollen samples were selected from five different sedimentary environments (sand dune, alluvial fan, wetland, floodplain and riverbed) found in three transverse sections in the middle reaches of the Heihe River. The results show that the five different sediment types have significantly different pollen assemblages: (1) sand dune: Chenopodiaceae - Artemisia - Nitraria - Poaceae; (2) alluvial fan: Nitraria - Chenopodiaceae; (3) wetland: Poaceae - Typhaceae - Chenopodiaceae – Artemisia ; (4) floodplain: Picea - Cyperaceae - Chenopodiaceae - Artemisia - Asteraceae; and (5) riverbed: Picea - Cyperaceae - Polypodiaceae - Chenopodiaceae – Artemisia . The auxiliary functions derived from analyses of the principal components also indicates a significant difference between pollen assemblages for the five different sediment types. This established the veracity of these particular pollen assemblages representing these five different sedimentary environments, thereby improving the reliability of our research results. Those results provide the fundamental information required for any reconstruction of the region's paleovegetation and paleoclimate based on the pollen records found in different sedimentary environments. [ABSTRACT FROM AUTHOR]

The ferrimagnetic iron sulfide greigite (Fe 3 S 4 ) occurs widely in sulfidic lacustrine and marine sedimentary environments. Knowledge of its formation and persistence is important for both magnetostratigraphic and paleoenvironmental studies. Although the formation mechanism of greigite has been widely demonstrated, the sedimentary environments associated with greigite formation in lakes, especially on relatively long timescales, are poorly understood. A long and continuous sequence of Pleistocene lacustrine sediments was recovered in the Heqing drill core from southwestern China, which provides an outstanding record of continental climate and environment. Integrated magnetic, geochemical, and paleoclimatic analysis of the lacustrine sequence provides an opportunity to improve our understanding of the environmental controls on greigite formation. Rock magnetic and scanning electron microscope analyses of selected samples from the core reveal that greigite is present in the lower part of the core (part 1, 665.8–372.5 m). Greigite occurs throughout this interval and is the dominant magnetic mineral, irrespective of the climatic state. The magnetic susceptibility (χ) record, which is mainly controlled by the concentration of greigite, matches well with variations in the Indian Summer Monsoon (ISM) index and total organic carbon (TOC) content, with no significant time lag. This indicates that the greigite formed during early diagenesis. In greigite-bearing intervals, with the χ increase, B c value increase and tends to be stable at about 50 mT. Therefore, we suggest that χ values could estimate the variation of greigite concentration approximately in the Heqing core. Greigite favored more abundant in terrigenous-rich and organic-poor layers associated with weak summer monsoon which are characterized by high χ values, high Fe content, high Rb/Sr ratio and low TOC content. Greigite enhancement can be explained by variations in terrigenous inputs. Our studies demonstrate that, not only the greigite formation, but also its concentration changes could be useful for studying climatic and environmental variability in sulfidic environments. [ABSTRACT FROM AUTHOR]

The Tucuruí Group of Neoproterozoic age outcrops in Tucuruí region, northeastern of Pará state, along with the transition between the Amazonian Craton and Araguaia Belt. The group is defined by a volcano-sedimentary sequence containing basaltic flows and diabase sill intrusions interbedded with siliciclastics deposits. The Tucuruí thrust fault override these sets rocky westward resulting in shearing, fracturing and fluid percolation in these rocks. The siliciclastic deposits consist of amalgamated subarkoses and siltstones, whose layers are oriented NNE-SSW direction with low dip to SE. In addition presenting coarsening and thickening upward. In this investigation were recognized two sedimentary facies associations: Deposits of Shoreface and Coastal Tempestites Face. This association suggests easy transport processes and sedimentation linked to a shallow marine environment, following the foreshore zone to zone shoreface under influence of wave storm. The petrographic analysis revealed the compositional and textural immaturity of arkosean sandstone and siltstone indicating nearby source area of provenance of mafic to intermediate igneous rocks. The sequence was subject to the mesodiagenetic sedimentary conditions. Thus, the siliciclastic deposits of Tucuruí Group represent the portion of a preserved segment influenced by coastal storm waves in a rift basin or foreland with nearby source area, composed of igneous rocks with strong relief, and marked predominantly by physical weathering. Basaltic volcanic flows occurred during the evolution of this basin.

Geochemical and mineralogical analyses, in addition to isothermal adsorption experiments on field samples, are used to characterise the sedimentary environments, reservoirs and adsorbed gas of the Upper Ordovician Wufeng–lower Silurian Longmaxi formations in the Sichuan Basin and its peripheral areas. The sedimentary environment of the Wufeng and the lower part of Longmaxi formations is a deep-water shelf with five different lithologies identified: siliceous shale, black shale, siltstone, biolithite limestone and bentonite. The black shale in the Wufeng and the lower part of Longmaxi formations is 50 m thick, with an average organic carbon content (TOC) of 3.81 wt% and a maturity (Ro) of 1.62%. Quartz comprises 54.94 vol% of the shale and positively correlates with the TOC. Micropores in the black shale include intergranular pores, intragranular pores, organic matter pores and microfractures. Among these pores, spaces between clay sheets and organic molecules represent a favourable storage space for the accumulation and preservation of oil and gas. The Langmuir volume parameter ranges between 1.52 and 3.01 cm3/g, with an average value of 2.33 cm3/g. The presence of organic matter pores and pores between clay sheets in the black shale is the main and controlling factor for accumulated gas. [ABSTRACT FROM PUBLISHER]

Detailed lithogeochemical data are reported here on early Paleozoic sedimentary rocks that host the large Howards Pass stratiform Zn-Pb deposits in Yukon-Northwest Territories. Redox-sensitive trace elements (Mo, Re, V, U) and Ce anomalies in members of the Duo Lake Formation record significant environmental changes. During the deposition of lower footwall units (Pyritic siliceous and Calcareous mudstone members), bottom waters were anoxic and sulphidic, respectively; these members formed in a marginal basin that may have become increasingly restricted with time. Relative to lower members, a major environmental change is proposed for deposition of the overlying Lower cherty mudstone member, which contains phosphorite beds up to ∼0.8 m thick in the upper part, near the base of the Zn-Pb deposits. The presence of these beds, together with models for modern phosphorite formation, suggests P input from an upwelling system and phosphorite deposition in an upper slope or outer shelf setting. The overlying Active mudstone member contains stratabound to stratiform Zn-Pb deposits within black mudstone and gray calcareous mudstone. Data for unmineralized black mudstone in this member indicate deposition under diverse redox conditions from suboxic to sulphidic. Especially distinctive in this member are uniformly low ratios of light to heavy rare earth elements that are unique within the Duo Lake Formation, attributed here to the dissolution of sedimentary apatite by downward-percolating acidic metalliferous brines. Strata that overlie the Active member (Upper siliceous mudstone member) consist mainly of black mudstone with thin (0.5-1.5 cm) laminae of fine-grained apatite, recording continued deposition on an upper slope or outer shelf under predominantly suboxic bottom waters. Results of this study suggest that exploration for similar stratiform sediment-hosted Zn-Pb deposits should include the outer parts of ancient continental margins, especially at and near stratigraphic transitions from marginal basin facies to overlying slope or shelf facies. [ABSTRACT FROM AUTHOR]

The siliciclastic Gadvan Formation from Abadan Plain, southwestern Iran, is highly bioturbated and allows relationships between changes in ichnocoenoses within a depositional system to be documented and placed in a high-resolution sequence stratigraphic framework. Relying on the sedimentary and ichnological characteristics, the siliciclastic succession is divided into two facies associations: a wave-dominated offshore-shoreface complex and a tide-river influenced delta. The first includes facies that have been deposited in shelf-offshore, upper offshore, lower shoreface and upper/middle shoreface environments, the latter includes facies that have been deposited in prodelta and delta front. Integrated ichnologic and sedimentologic studies of the Gadvan Formation, allow distinction between prodelta and delta front and open marine deposits. With the identification of maximum flooding and ravinement surfaces as bounding surfaces of the stratal units, detailed analysis on systematic changes in the stacking pattern (cycle thickness, cycle type, and facies proportion) are made. Eight ichnocoenoses could be differentiated in the studied sections. The positions of the ichnocoenoses within genetically related stratal units (genetically related ichnocoenoses), indicate three large-scale cycles (DS1 to DS3, from oldest to youngest). The cyclical nature of the Gadvan Formation is attributed to low-amplitude eustasy in greenhouse conditions formed under interaction of eustatic high-frequency cycles and longer term tectonically driven sea-level variations during the long-term transgressive sea-level trend of the early Cretaceous. Stratigraphic architectural style of sequences DS1 to DS3 (which includes scarce evidence of lowstand deposits, partial or total truncation of the HST, and predominance of thick transgressive deposits), is remarkably similar to long-term transgressive sea-level trend of the Early Cretaceous across the Arabian Plate. This study suggests a more relatively seaward position of the siliciclastic successions of the Gadvan Formation of Abadan Plain than the Mesopotamian Basin (upper Zubair Formation equivalent in western Iraq and Kuwait), which would be concordant with the prevailing view of an easterly prograding coastline across the Arabian Plate. This study reveals important sedimentological and ichnological features and permits the development of predictive models for the paleoenvironmental and sequence stratigraphical significance of trace fossil assemblages that can be readily compared or translated to analogous depositional systems worldwide. The ichnological analysis is based on cores and can be especially applied to evaluate the applicability of current ichnological models to the study of Cretaceous reservoirs of western Iraq, Kuwait and western Saudi Arabia. [ABSTRACT FROM AUTHOR]

Storms, associated with strong winds and heavy rains, are often the most severe physical disturbances in shallow coastal areas causing instability to sedimentary environments. We hypothesized herein that if storms influence short-term assemblage structure of macrofauna, then assemblages should change after storms, while remaining relatively stable over calm weather conditions. The study was conducted at the subtropical Paranaguá Bay, in southern Brazil. We selected four 700 m² sites, at the estuarine outlet, to monitor changes in number of species, number of individuals and Shannon diversity. Sampling was arranged considering the weather forecast so that both before and after conditions could be recorded. Data of each site was tested separately to access the significance of specific (before/after) comparisons using t tests. There were no clear effects of storms on macrofaunal species richness, abundance and diversity at the four sampled sites. Conversely, we showed that short-term variation in abundances occurred regardless of weather conditions. Increased dispersal may be the most common process associated with storms instead of mortality. Storms that intermittently affect the southern coast of Brazil can be thus seen as minor driving forces of shallow-water estuarine macrofauna. Effects of extreme meteorological events remain to be assessed.

Se analizó la distribución espacial y las principales características texturales de 234 muestras de sedimentos superficiales de la bahía de Cartagena. Para caracterizar los ambientes de depósito en el fondo de la bahía se aplicaron tres funciones discriminantes para diferenciar entre: (i) depósitos de playa y marino somero agitado, (ii) depósitos fluviales y marino someros, y (iii) depósitos fluviales influenciados por corrientes de turbidez. Los sedimentos predominantes fueron lodos medios (5,35 ± 1,2 φ), pobremente clasificados (σ = 1,63 ± 0,8), con notable asimetría (Sk = -0,052 ± 0.2) y curtosis (k) de 0,84 ± 0,4. Se encontró dos tipos principales de depósitos recientes en la bahía de Cartagena: marino somero agitado, de dominio fluvial, y depósitos de corrientes de turbidez, de dominio fluvial. Los contenidos más bajos de arena (

A series of Quaternary lacustrine braid deltas on the shores of Lake General Carrera in southern Chile formed as a result of falls in lake level. Each delta comprises two components, the delta fan and the beach embayment, each in turn comprising an onshore subaerial and an offshore subaqueous element. The delta fans have a classic Gilbert form with a braided delta top and a steeply inclined delta front. Adjacent to the fans are concave beach embayments that formed parallel with the deltas as they prograded into the lake. The delta sediments consist predominantly of matrix- and clast-supported gravéis to a total composite thickness exceeding 400 m. The depositional environments are dominated by ephemeral river flooding and by storm-driven waves. Beach sediment is sorted, rounded, winnowed and transported alongshore by waves to fill the beach embayment with ridges of very well sorted and well-rounded gravel. A gently-dipping shoreface platform occurs up to 100 m offshore between the beach and the brink point. From the brink point, in water depth of about 8 m, sediment cascades down the steep delta front slope to form long foresets extending to the lake floor. The sedimentary successions therefore wedge in the opposite direction from those of tectonically controlled basin margins where fan growth keeps pace with basin subsidence.Una serie de deltas entrelazados lacustres, pertenecientes al Cuaternario, ubicados en las costas del lago General Carrera, en el sur de Chile, se formaron como resultado de caídas en el nivel del lago. Cada delta consta de dos componentes: el abanico deltaico y la zona de embahiamiento. Cada uno de ellos tiene, a su vez, un elemento subaéreo costero y un elemento subacuático. Los abanicos deltaicos tienen una forma Gilbert clásica con una parte superior de ríos entrelazados y un frente deltaico empinado. Adyacente a los abanicos aluviales existen bahías cóncavas de playa que se formaron de manera paralela a los deltas a medida que estos progradaron hacia el lago. Los sedimentos deltaicos consisten predominantemente de gravas matriz y clastosoportadas con un grosor total compuesto que excede los 400 m. Los ambientes depositacionales están dominados por inundaciones efímeras del río y por olas de tormenta. Los sedimentos de playa están seleccionados, redondeados y fueron transportados a lo largo de la costa por las olas para rellenar el embahiamiento de la playa con dorsales de gravas muy bien clasificadas y redondeadas. Una plataforma del 'shoreface' de baja pendiente ocurre hasta 100 m agua adentro, entre la orilla y el borde. Desde el borde del lago, en el agua hasta los 8 m de profundidad, el sedimento cae en cascadas por la empinada pendiente del frente deltaico para formar grandes 'foresets' que se extienden hacia el fondo del lago. La sucesión sedimentaria se acuña, en consecuencia, en una dirección opuesta a la de aquella, de márgenes de cuenca controlados tectónicamente ('brink point'), donde el crecimiento de los abanicos mantiene un equilibrio con la subsidencia de la cuenca.