Sedimentary Environments Research Articles

Geoelectric Subsurface Characterization in the Emerged Portion of the Barra Falsa Channel using the Ground Conductivity Meter (LIN-EM), Bojuru, RS, Brazil

Geophysical investigation in the coastal region of the emerged portion of Barra Falsa, Bojuru, RS, Brazil, provided valuable information about the depositional evolution and paleoenvironmental changes that occurred during the Quaternary period. The combination of electromagnetic surveys, analysis of stratigraphic wells, 3.5 kHz reflection seismic and previous geological data allowed for a comprehensive characterization of sedimentary environments associated with sea-level fluctuations. Electromagnetic surveys using the LIN- EM method with the Geonics EM34TM system revealed different conductivity responses in the subsurface, which could be interpreted in relation to depositional events. Five depth intervals were identified and related to specific events, such as the closure of the Barra Falsa channel, estuarine infilling, and channel drowning during marine transgressions. Furthermore, the comparison of the results of electromagnetic surveys with data from stratigraphic wells allowed calibration of indirect data. This multidisciplinary approach highlights the importance of integrating geophysical and geological techniques to reconstruct coastal environment evolution over time. This study provides a detailed insight into paleoenvironmental and depositional changes on the coast of Bojuru, demonstrating how these techniques can significantly contribute to future research and the sustainable management of coastal areas. The knowledge gained here is essential for understanding the dynamics of coastal zones and the influences of sea-level variations in the Southern region of Brazil.

A review of the Neogene formations and beds in Slovenia, Western Central Paratethys

Neogene sedimentary successions are found in eastern and northeastern Slovenia. Their formation was closely related to the evolution of the western part of the Pannonian Basin System and the Central Paratethys; it was influenced by global transgressive and regressive cycles as well as by global, regional and local tectonics. Several formations and beds were defined within the Neogene sedimentary successions which can be found in three separate areas. The first one includes the formations north of two major fault systems, the Periadriatic Fault System and the Mid-Hungarian Zone, which were associated with the Mura-Zala and the Styrian Basins, respectively. Successions south of these major faults are not formally connected to any of the major basins and developed in two distinct parts: a strip between Tunjice and Kozjansko to the north and the Krško area to the south. From the Egerian to the early Badenian, different areas exhibit different types of sedimentation, whereas from the middle Badenian onwards, sedimentation in different zones is partly comparable, depending on the type of depositional environment. Egerian and Eggenburgian sediments are only found south of the above-mentioned major fault zones, whereas Karpatian sedimentation only occurred north of them. Sediments in both areas are characterized by alternation of shallow marine, brackish and terrestrial sedimentation. In contrast, sedimentary environment in the Badenian evolved from a terrestrial, mainly fluvial environment with alluvial fans, through a transitional stage (delta and lagoon) to a shallow and deep marine environment. The Sarmatian sequences reflect a brackish environment with decreasing salinity and continue into extensive Pannonian delta systems that gradually fill the basins from west to east. The formations that correspond to the Pannonian in the Mura-Zala Basin can be correlated with the formations in the Krško area. The Pliocene is characterized by terrestrial sedimentation with the formation of rivers and lakes in the newly established intramontane basins.

Analysis of genetic sandbodies and coal seams with coal-bearing of Middle-Lower Jurassic in the Junggar Basin

IntroductionThe sediment genetic mechanisms have always been an important branch of the “source-sink” system, and it is also a research hotspot.MethodsConglomerate, sandstone, and coal are developed of Middle-Lower Jurassic in the Junggar Basin, and the genetic mechanism is not clear, which restricts further exploration of oilfield. Based on the core carefully, test data, and outcrop sections, Badaowan and Xishanyao formations are analyzed.ResultsFive types of conglomerate lithofacies and sandstone lithofacies, two kinds of mudstone lithofacies, and one type of coal are identified. Based on the structural-genetic mechanism, the debris flow and traction current with conglomerate are developed, and a method of the semi-quantitative identifying index is proposed based on the sedimentary sequence of lithological characteristics, MPS/BTh, and grain size characteristics as the identification criteria. Depending on fluvio-delta, the genetic bodies of the distribution channel, subaqueous distribution channel, mouth bar, braided channel, and overbank sandstone are divided.DiscussionBy integrating structural, paleoclimatic, and sedimentary environment, it was observed that coal in the Badaowan Formation has the characteristics of continuous and stable distribution of thick layers, whereas multiple sets of discontinuous and instable distribution are observed in the in Xishanyao Formation. Finally, the filling model is established, and the superposition and distribution of sandbodies are clarified.

From biomolecules and organic matter to sedimentary environments and basin analysis: a special issue in honour of Ralf Littke—an introduction

From biomolecules and organic matter to sedimentary environments and basin analysis: a special issue in honour of Ralf Littke—an introduction

Comparative study on genesis mechanism of high arsenic groundwater in typical alluvial plain of the Upper and lower Yellow River, China

Groundwater with naturally high‑arsenic (As) concentrations is a pervasive issue across several major plains (basins) traversed by the Yellow River in China. The genesis of this high-As groundwater and its interrelationships among different plains (basins) have consistently been focal and challenging topics for domestic and international experts. The study focuses on the Hetao Basin in the upper Yellow River and the North Henan Plain in its lower reaches. Selecting typical profiles within the study area, a comparative analysis is performed based on the hydrochemical and isotopic signatures of these profiles. This analysis elucidates the distribution patterns, formation environments, and hydrogeochemical evolution models of high-As groundwater under the influence of different sedimentary environments. The results demonstrate that the shallow groundwater in the upper Yellow River is progressively salinizing, and conversely, the lower reaches are exhibiting a gradual alkalization. Redox conditions, the degree of evaporative concentration, and the intensity of groundwater recharge can influence the distribution disparities of high-As groundwater in the upper and lower reaches of the Yellow River. High-As groundwater in the Hetao Basin of the upper Yellow River is predominantly affected by the strength of groundwater reduction. Conversely, in the North Henan Plain of the lower Yellow River, the chemical conditions of the groundwater are more intricate, with As enrichment being influenced by a confluence of factors such as redox conditions, evaporative concentration, and the intensity of groundwater replenishment.

Sedimentary dynamic processes affected by tropical cyclones and anthropogenic forcing in a small-scale estuary: The Sheyang River Estuary, China

Amid the robust landward migration of tropical cyclones (TCs) in the context of global warming, the sedimentary dynamic processes in coastal areas are increasingly affected by TCs. Concurrently, coastal environments face tremendous stress from anthropogenic interventions, such as land reclamation and jetty construction. However, most research puts more emphasis on TC impacts on large-scale estuaries or marginal seas, leaving the sediment dynamics in small estuaries, particularly under the influence of TCs and man-made structures, largely unexplored due to the limited field data. To address this issue, this study took the Sheyang River Estuary (SRE) as an example and explored the sediment dynamic responses to TCs and the jetty construction during Typhoon Lekima in August 2019, utilizing the Finite Volume Coastal Ocean Model (FVCOM). The results showed that the rotating wind field of Lekima induced rapid variations in wave height, residual water level, and currents at different typhoon stages and strengthened the sediment resuspension and alongshore transport. Furthermore, by comparing the effects of Lekima with Typhoon Chan-hom in July 2015, we found that TCs with different tracks produced markedly different dynamic processes, yet all facilitated sediment exchange between the northern and southern areas within the SRE. The study also highlighted the impact of jetty construction on sediment transport during typhoons, noting that jetties can disrupt the typhoon-induced alongshore sediment flux and create eddies on either side by altering sediment advection. In the navigational channel area, the construction of jetties can strengthen the along-channel estuarine circulation during typhoon events, potentially leading to severe channel siltation by trapping riverine sediments and inducing net landward sediment transport. While site-specific, this study provides valuable insights into the combined effects of extreme events and human interventions on sedimentary environments in small estuaries.

Ecological risks caused by neonicotinoid pesticides in sediments: A case study of freshwater basins in China.

Neonicotinoid insecticides (NNIs) are extensively used in agricultural production in China due to their selective neurotoxicity towards target insects. In recent years, the rapid development of agriculture has increased the use and residue of NNIs. Consequently, the sediment environment, serving as the ultimate sink, is significantly impacted by NNIs. Upon release into the environment, NNIs can enter the human body through the food chain, posing potential ecological and human health risks. This study analyzed 79 sediment samples from two major river basins in North and South China, the Liaohe River basin in Liaoning Province and the Jianjiang River basin in Guangdong Province. The content, composition, distribution, and source of eight NNIs were analyzed, and assess the ecological and human health risks of the target compounds in these regions. The results indicated that the average concentration of NNIs in the sediments of the Jianjiang River basin (2.34 μg/kg) is slightly higher than that of the Liaohe River basin (2.32 μg/kg), and the sources of NNIs in the two areas were different, with differences in the sources of NNIs likely attributable to varying types of agricultural production. The risk assessment revealed that the ecotoxicological and public health risks were more pronounced in the Jianjiang River basin compared to the Liaohe River basin, underscoring the critical need for surveillance and management of hazardous substances like NNIs. The insights findings from this study can provide scientific guidance for the risk evaluation and environmental management of NNIs.

Bayesian statistical analysis reveals spatial heterogeneity in Cyclone Thane deposits from Southeast India

Modern and geological records of storm sedimentary deposits preserved on siliciclastic coastlines are important archives to evaluate the past and current magnitude and impacts of.storms. Examination of modern storm deposits also offers the opportunity to evaluate the similarities and differences between storm and other coastal overwash processes and hazards.We examined the stratigraphy and sedimentary characteristics of the 31st December 2012 Cyclone Thane and underlying coastal units from 14 pits from six sites from the coastal zone of Tamil Nadu Province, southeast India. We analysed the grain size parameters, grain shape, and heavy mineral proportions of each deposit in high resolution and examined the sedimentary structures of each unit. For the first time, we use Bayesian factors to quantitatively evaluate the similarities and differences between the storm sedimentary deposits and other co-located coastal sedimentary deposits. At several sites, the storm deposits differ in several parameters from the underlying coastal deposits, but at some locations, distinguishing between different depositional units cannot be achieved. In comparing the storm deposits from the different sites, mean grain size results in the most coherent pattern with closely located sites having similar mean grain size, and more southerly sites being finer grained. The other measured parameters show a far less coherent pattern with adjacent sites often preserving larger differences than more distal sites attesting to very local hydrodynamic variations during sediment deposition. As with the sedimentary parameters, the sedimentary structures formed during sediment deposition preserved at each site are highly variable. To date, the presence of terminal foresets at the landward edge of washover fans remains the only diagnostic feature of storm deposition, but that this feature is not ubiquitous across all storm deposits. Our findings demonstrate the spatially heterogeneous nature of storm sediment deposition and the challenges of identifying storm deposits in coastal siliciclastic sequences. The use of Bayesian statistical approaches also offers a robust method for evaluating and discriminating between coastal sediment deposits that has many advantages over traditional frequentist approaches. This method can easily be applied to other sedimentary depositional environments.

Mass organic matter accumulation induced by rapid redox variations in lakes: Evidence from the Miaoxi area, Bohai Bay Basin, China

The Member 4 of the Paleogene Shahejie Formation (Es4) in the Bohai Bay Basin is interspersed with a set of high-quality source rocks typified as intercalation of red and black mudstones. A large amount of petroleum (crude oil) originates from these source rocks. The Paleocene–Eocene Thermal Maximum (PETM) event occurred during the deposition of Es4 in the Bohai Bay Basin, and the organic matter enrichment model under this event is worth further investigation due to its relationship with and influence on petroleum accumulations. Well LK25-A, as the first oil exploration well drilled into the Es4 in Miaoxi area, serves as a valuable case to study organic matter accumulation. In this study, we integrate total organic carbon (TOC), Rock-Eval pyrolysis, microscopic observation, vitrinite reflectance (VRo), elemental analysis, and gas chromatography–mass spectrometry (GC–MS) to evaluate the hydrocarbon generation potential, organic matter types, thermal maturity, and sedimentary environment of the Es4 in Miaoxi area. The analysis of maceral and rock pyrolysis data reveals that Type I and Type II organic matter make up the majority of Paleogene mudstones in this region. The TOC and rock pyrolysis data show that mudstones in this area have high organic matter abundance and oil-generation potential. The measured vitrinite reflectance distribution of mudstone samples, which ranges from 0.3% to 0.74%, demonstrates that the Paleogene strata are at the immature to mature stage, and the samples from this area contain a sizable amount of bituminite and mineral-bituminous groundmass. The analysis of biomarkers in the mudstone samples indicates that most of the mudstones in this area are in lacustrine and brackish-hypersaline lacustrine environment under a reducing condition, and some of the red mudstones in the Es4 are formed under a suboxic condition. Based on the size and morphology of the pyrite framboid, the redox conditions of the water mass during deposition or diagenesis are further analyzed. The ratio of the size of framboid pyrite (D) to the size of its micrograins (d) suggests that the Es4 black mudstone developed in an anoxic sulfuretted water environment. Both the inorganic and organic geochemical indexes show that the Paleogene paleoclimate has a great influence on the source rocks of Es4 in this area. The distribution of red–black strata in the area is the result of the combined action of the water redox state and the climatic variation during the PETM event. The development models of organic-rich source rocks from the Es3 and Es4 in this area have been created in light of potential connections between rapid redox variation and the PETM event during the Paleogene. These models may offer a theoretical guidance for petroleum exploration in Miaoxi area of Bohai Bay Basin and other contemporaneous continental basins around the world.

Current Status of Stratigraphy of the Proterozoic Cuddapah Basin, Southern India

ABSTRACT The Cuddapah basin in southern India is one of the large Proterozoic basins with rich and strategic mineral resources. As a repository of sedimentary and tectonic records spanning from the Paleoproterozoic to the Neoproterozoic, the intracratonic Cuddapah basin holds vital clues to regional crustal development, paleogeography and tectonic underpinnings of passive margin sedimentation. In this article, a brief overview of the stratigraphy of the basin is presented with emphasis on recent developments in our understanding of the physical stratigraphy controlled by multiple unconformity bound sequences suggesting multiple transgressions of the sea, the emerging geochronological constraints, and broad sedimentary environments of different formation level units. Some issues of stratigraphic classification originating from allochthonus nature of the deformed rock successions of the Nallamalai fold belt have also been examined.

Grain size and shape analysis of recent and paleo sediments along Poyang Lake with insight into its environmental significance

Grain shape is a crucial sedimentological attribute commonly employed for reconstructing depositional environments and transport history. The new dynamic image analysis (DIA) techniques enable testing a large number of individual mineral grains simultaneously and overcomes many shortcomings of traditional visual evaluation. However, there is a relative dearth of comprehensive analysis on large quantities of sediments in recent and geological period to accurately document their grain shape properties and further evaluate their applicability in distinguishing sedimentary setting and its environmental significance. In this study, we measured the grain shape and size of 77 samples collected from modern surface sand (28 beach sand and 17 dune sand samples) and stratigraphic sediment (16 paleo-dunes sand and 16 paleo-lacustrine sand samples) along the Poyang Lake in southeastern China using the DIA method, and optically stimulated luminescence (OSL) dating was used to constrain the age of stratigraphic sediments from two sand hill sections. Also 217 published grain shape data from various sedimentary environments (coastal beach, desert dune and fluvial sand) were compiled as comprehensively assess the applicability of grain shape discrimination for sedimentary setting. Our results show the significant difference on grain shape feature among fluvial, coastal beach and dune sand. Dune sand exhibit the highest values for circularity (Ci), symmetry (Sy), aspect ratio (AR), and convexity (Cx), while fluvial sand displays high Ci, Sy, Cx value, and lowest AR value. This indicate that the grain shape can be a powerful tool for discriminating sedimentary setting. Principal component analysis shows that circularity and aspect ratio effectively describe the shape of the analyzed sediment and are decisive indicators for identification depositional environments, whereas the convexity has limited sensitivity in distinguishing grain edge roundness. The paleo-lacustrine sand (PLS) intercalated within the sand hill profiles returns OSL age of age of ∼ 26.5 ± 1.4 ka, which indicate the emergence of interdune lake rather than high lake level of Poyang Lake. PLS and modern beach sand (BS) exhibiting identical grain shape characteristics to those of modern aeolian dune sand (DS) suggested the occurrence of aeolian-fluvial interaction processes in our study area during the Last Glacial Maximum and present day. The paleo-dune sand (PDS) samples, yielding OSL age of 1.2 ± 0.1 ka, are characterized by higher Ci, Sy, and AR, indicating strong aeolian activity and dune reworking during the past two millennia along the Poyang Lake.

Complete genome sequence of a methanotrophic bacterium, Methylomicrobium lacus strain 22M6SE5-12 isolated from a freshwater sediment environment.

We assembled the complete genome of Methylomicrobium lacus strain 22M6SE5-12 isolated from a freshwater sediment in South Korea. The genome consists of a 4.36-Mbp chromosome and two plasmids and has 3,961 coding sequences, 12 rRNA genes, and 55 tRNA genes. We identified a gene set encoding the particulate methane monooxygenase subunits.

The post-depositional evolution of mesoproterozoic to early neoproterozoic tight sandstone reservoirs, São Francisco basin, Brazil

This study presents the first comprehensive assessment of unconventional gas reservoirs in the Proterozoic sequences of the intracratonic São Francisco basin, providing depositional and post-depositional characterization and insights into reservoir quality. Detailed stratigraphic, petrological, and seismic analyses, integrated with 2D seismic data, were performed to evaluate the influence of diagenesis and hydrothermal fluids. The drill core was drilled in the central sector of the basin and within the southern border of the Pirapora aulacogen, in a 303 m-thick interval of the Paranoá-Upper Espinhaço sequence. The petrological analysis shows arkoses and sublitharenites as well as conglomerates, siltstones and mudstones successions deposited in deltaic, fluvial braided and marine depositional systems. Six sedimentary environments were identified, from the base to the top: (i) deltaic plain, (ii) delta front, (iii) braided fluvial, (iv) delta front, (v) prodelta and (vi) basin plain. The integration of seismic data review three depositional domains, characterized by lower frequency arranged to transgressive-regressive cycles identified by gamma ray, resistivity and density logs. The studied strata review eo - and mesodiagenetic alterations, being also influenced by intrusion-related hydrothermal and contact metamorphism. The main diagenetic events resulted in cementation of calcite (0.84%), chlorite (1.23%) and silica (6.19%), which largely obliterated porosity at the shallow burial depths. The main secondary porosity is intergranular, with minor contributions to intragranular, fracture, moldic and vugular. Diagenetic processes as well as the influence of hydrothermal processes highlight the complexity of post-depositional processes in these units. The presence of natural helium and hydrogen within the basin also suggests that these reservoirs should be considered in future exploration campaigns targeting unconventional energy resources.

The eastward intrusion of the Lena River into the East Siberian Sea since the early Holocene

The sedimentary environments and material sources of the eastern and northeastern Lena Delta differ in coarse-grained components and garnet geochemistry, particularly in the Buor-Khaya Bay, where the material composition is primarily influenced by the Lena River, while the Yana Bay sediment is controlled by the Yana River. Analysis of detrital minerals in core LV83–32-3, located in northern Yana Bay, indicates dominant primarily fluvial input from the Yana River, with secondary contributions from the Lena River and minor inputs from coastal permafrost erosion since the early Holocene. During the sea-level rise period from 8.5 to 5 ka, four significant fluvial discharge events from the Yana River were identified, marked by high mica contents, associated with multiple climate warming events. From ∼5 to 1.6 ka, an increasing Lena River runoff transported coastal permafrost material via river flow or river ice, evident in a gradual rise in plagioclase content. After 1.6 ka, a sharp decrease in hypersthene and garnet contents suggests reduced Lena River discharge, coinciding with a similar decline in hypersthene content in the core of the East Siberian Sea since 1.8 ka. Two prominent Lena River fluvial events, dated to 7.1 and 3.7 ka, are identified by the event layers containing minerals typical of the Lena River, rich in hypersthene, garnet and zircon, along with substantial coarse-grained debris such as quartz, plagioclase, siderite and clayey tubes. These two events are also recorded in the East Siberian Sea. The 7.1 ka discharge event may coincide with the separation of the New Siberian Islands from the mainland, while the 3.7 ka event represents a widely distributed Lena River floodplain event.

Neogene drainage evolution of SW Anatolia (Türkiye): Integration of morphotectonics, drainage and denudation analyses

AbstractThis study integrates denudation analysis with morphotectonic characteristics, facies associations and drainage analysis to investigate the landscape evolution of SW Anatolia. Age‐Elevation Relationship (AER) plots of published thermochronological data from drainage divides, valleys and preserved paleo‐geomorphological landscape remnants provide insight into the region's drainage evolution. Cooling and denudation events identify the timing of divide formation, windgap formation and divide breaching, which leads to watergap formation.We have subdivided SW Anatolia into distinct morphotectonic domains. Among these, the Gediz and Büyük Menderes faults and the Selimiye Shear Zone fragmented the Menderes Metamorphic Core Complex into three each of which experienced different cooling histories based on denudation analysis utilizing various low‐temperature thermochronometers.Hypsometric integral and channel profile analyses demonstrate significant variation in landscape maturity and drainage basin modifications over time. These analyses, combined with the interpretation and mapping of windgaps, watergaps and stream deflections, as well as the depositional environments of sediments and volcanic sequences, enable the reconstruction of drainage patterns from the early Miocene to Recent.During the middle Miocene, the Sakarya drainage basin dominated central and eastern SW Anatolia, with the Gediz drainage basin being a minor part of the Küçük Menderes basin. The Büyük Menderes drainage basin, in contrast, drained the southern portion of SW Anatolia, while the Bakırçay catchment extended into the northern Gediz basin. By the late Miocene, the Sakarya drainage basin had lost a significant portion of its hinterland to the Gediz basin and several newly isolated basins, while also capturing the Burdur and Beyşehir basins, along with the mid‐ and upstream sections of the Büyük Menderes basin, thereby reducing its area by two‐thirds. In the Pliocene, the Gediz drainage basin contracted by approximately 80%, while the Büyük Menderes basin expanded to absorb the Gediz and Tavas basins. During the Quaternary, the Büyük Menderes basin further shrank by around 60% as isolated basins formed in the east. Recent tectonic activity has led to the Gediz basin recapturing parts of its upstream area, while the Büyük Menderes basin regained previously isolated sections of the Gediz basin. The Dalaman and Eşençay basins also captured upstream isolated basins, while the Burdur basin was captured by the Aksu River, isolating the Beyşehir basin from Burdur.These episodes of drainage reorganization are driven by dynamic topography, influenced by slab‐edge processes and intensified by the westward escape of the Anatolian Block. The westward motion, combined with slab‐tear‐driven vertical movements, has led to substantial reconfiguration of the drainage networks in SW Anatolia over time.

Formation Mechanism of Muji Travertine in the Pamirs Plateau, China

The Muji spring travertines, located in the Muji Basin in the eastern Pamirs Plateau, represent a typical spring deposit found on plateaus that is characterized by arid and semi-arid climatic conditions. However, its formation mechanisms remain poorly understood. This study aims to explore the recharge processes of the spring, the sedimentary environment, and the genetics of Muji spring travertines through a comparative analysis of conventional hydrochemistry, H-O stable isotope analysis of both spring and river water, and petrographic observation, as well as in situ analysis of major and trace elements present in calcite within travertines. The basin is surrounded by mountains with a topography that facilitates groundwater convergence within it. Carbonate-bearing strata are extensively developed around the basin, which serves as a crucial material foundation for travertine development. It infiltrates underground through fractures and faults, interacting with carbonate rocks to produce significant amounts of HCO3−, Ca2+, and Mg2+. The observed range of isotopic compositions (δ2H, −102.27‰ to −96.43‰; δ18O, −14.90‰ to −14.36‰) in water samples suggests that their primary origin was from glacial and snowmelt sources. The concentration of HCO3− in spring water samples exhibits significant variability, with the highest value being 1646 mg·L−1, which deviates significantly from the typical composition of karst groundwater. During its migration, groundwater undergoes the dissolution of gaseous CO2 derived from deep metamorphic processes, leading to variable degrees of mixing with geothermal groundwater containing elevated concentrations of dissolved components that enhance the dissolution potential of carbonate rocks. Eventually, upwelling occurs along the Southwestern Boundary Fault of Muji, resulting in the formation of linear springs characterized by CO2 escape. The Muji laminated travertines exhibit distinct white and dark laminae, and radial coated grains consisting of micritic and sparry layers. Chemical composition analyses reveal significant differences in the trace and rare-earth element composition, as well as the Mg/Ca ratio, of the two types of travertines. Specifically, the micritic laminae of the pisoid (Mg/Ca = 0.019; Sr = 530 × 10−6; Ba = 64.6 × 10−6) and the dark laminae of the laminated travertine (Mg/Ca = 0.014; Sr = 523 × 10−6; Ba = 48.1 × 10−6) exhibit generally higher Mg/Ca ratios and Sr, Ba contents than the neighboring sparry laminae (Mg/Ca = 0.012; Sr = 517 × 10−6; Ba = 36.6 × 10−6) and white laminae (Mg/Ca = 0.006; Sr = 450 × 10−6; Ba = 35.6 × 10−6). The development of laminated travertines and radial coated grains here is attributed to periodic changes in groundwater recharge induced by seasonal temperature fluctuations, as evidenced by the structural characteristics of the two types of travertines and the trace element analysis of different layers. Algae play a role in forming the dark laminae of laminated travertines and the micritic laminae of pisoids.

Evaluation of the Sequence Stratigraphy and Sedimentary Environment of the Asmari Formation in the Southwest of Iran: (Case Study of Gurpi and Asmari Anticlines Masjed Soleiman Oil Field)

Evaluation of the Sequence Stratigraphy and Sedimentary Environment of the Asmari Formation in the Southwest of Iran: (Case Study of Gurpi and Asmari Anticlines Masjed Soleiman Oil Field)

Seismic geomorphology and reservoir conditions of a Middle Miocene submarine channel system in the Taranaki basin, New Zealand

Deepwater channels function as vital deep-sea hydrocarbon reservoirs and as major routes for moving terrestrial clastic sediment to deepwater environments. A high-resolution sequence stratigraphic framework was built for the deepwater area of the Taranaki Basin using high-resolution three-dimensional (3D) seismic data, and various seismic interpretation techniques, including seismic attribute analysis, were applied. The principal controlling factors and petroleum development potential of the Middle-Miocene channel system were investigated with sequence stratigraphy and seismic geomorphology. Four understandings were primarily attained in this study: (1) depending on the different levels of the channel surfaces, the channel system can be divided into five sedimentary units (SU1-SU5), which correspond to the five stages of channel system evolution. These surfaces include one primary draping surface (PDS), five secondary channel erosion surfaces (SCES), and several tertiary channel erosion surfaces (TCES). (2) with the use of seismic facies analysis, six sedimentary elements were identified in the channel system: pelagic deposits (PDs), mass transport deposits (MTDs), outer levee complex (OLC), inner levee and terrace complex (ILTC), and turbidite channel complexes (TCCs). (3) The sedimentary evolution of the channel system was jointly influenced by multiple factors. The sediment supply and submarine geomorphology can directly affect the internal stacking and migration patterns of the channel. In contrast, tectonic activity and relative sea level fluctuations can indirectly affect the sedimentary characteristics of the channel by regulating the components and scale of clastic sediment. (4) SU1, SU2, and SU3 are primarily filled with coarse-grained sediments, which can serve as high-quality hydrocarbon reservoirs. In contrast, SU4 and SU5 can serve as regional cap rocks because they are filled with fine-grained sediments, and the overall channel system can represent a potential hydrocarbon reservoir-cap combination, which can be viewed as a significant research target for upcoming deepwater exploration. Clarifying the sedimentary properties and primary controlling factors at the various evolutionary stages of deepwater channels is vital for predicting the hydrocarbon development potential of the basin and reducing the drilling risk. This also helps with the development of deepwater basins with similar sedimentary environments in New Zealand and elsewhere in the world.

Microplastics alter the migration and transformation of vanadium in the riverine sediment environment

Microplastics (MPs, size <5 mm) have emerged as environmental hazards and are widespread in the environment. They can significantly alter the reactivity and mobility of co-occurring elements. Vanadium, a strategic resource, was witnessed rising in the environment because of extensive anthropogenic activities. Nevertheless, the impact of MPs on the migration and transformation of vanadium has yet been investigated. This study therefore investigated the vanadium behavior in riverine sediment and overlying river water in the presence of MPs. 1.5 g representative non-degradable MPs (polyamide, polyethylene terephthalate) and biodegradable MPs (polybutylene succinate, polyhydroxyalkanoates) were separately amended into the reactors, which contained 50 mg vanadium-rich sediment. After incubation for 60 days, vanadium in the sediments decreased substantially, while vanadium increased in the overlying water, especially in reactors amended with biodegradable MPs. The biodegradable and non-degradable MPs were found to influence vanadium behavior through distinct mechanisms. The amendment of non-degradable MPs did not substantially impact humification process, during which the mobile and reducible vanadium passively leached out from the riverine sediment and migrated into overlying water. Conversely, amendment of biodegradable MPs significantly enriched several microbial genera (e.g., Massilia) in the MPs biofilm. These genera confer heavy metal resistance and synthetic polymer degradability, and were significantly correlated with specific sediment organic matter components (C3, Ex/Em = 270/352; C4, Ex/Em = 280(370)/504). The microbial community was found to alter sediment DOM when biodegradable MPs were introduced. These changes in microbial dynamics and sediment chemistry subsequently influenced the bioavailability and mobility of vanadium within the riverine sediment.

New insights into Holocene dust activity in eastern Uzbekistan

Central Asia is a substantial source of long-range-transported dust, yet the historical and geological variability of dust activity in this region remains poorly understood. This study presents a Holocene record of dust activity from a 6.2-m loess section located near Tashkent in the westerlies-dominated region of eastern Uzbekistan, Central Asia. Utilizing the quartz optically stimulated luminescence dating protocol, we employed grain-size analysis and trace-element geochemistry to reconstruct Holocene dust activity. Dating indicated that this section was deposited over the last 9.6 ka. Four grain-size end-member (EM) components were identified, each representing different atmospheric circulation patterns and sedimentary environments. End-member 2, with a modal size of 11.2 μm, likely represents particles transported by upper-level westerlies, while EM 3, with a modal size of 28.3 μm, is associated with near-surface winds linked to dust storms. Zirconium is concentrated in coarse particles, whereas Rb is enriched in finer particles during dust deposition. Therefore, higher Zr/Rb ratios indicate stronger or more distant dust transport; hence, the Zr/Rb ratio is a reliable indicator of dust activity. Holocene dust activity was reconstructed using the EM 3 component and Zr/Rb ratio, revealing several extreme dust-storm events. During the early–middle Holocene (9.6–5 ka), dust activity was stronger but less frequent compared with the subsequent shift to lower intensity but higher frequency dust events. The long-term orbital-scale decline in Holocene dust activity can be attributed to reduced solar insolation and weakening of the Siberian High since the early Holocene. On a centennial to millennial scale, extreme dust-storm events are teleconnected with cold ice-rafted debris events in the North Atlantic. Projections for the coming century suggest that dust activity in eastern Uzbekistan may further decline, accompanied by an increase in precipitation. This study provides new insights into understanding and predicting dust storms in Central Asia.