Period Of Deposition Research Articles

Sedimentary Environment of the Permian Marine Shale in the Kaijiang‐Liangping Trough, Sichuan Basin, China: Implications for Organic Matter (OM) Accumulation

ABSTRACTThe Permian shales in the Kaijiang‐Liangping Trough within the Sichuan Basin represent a promising frontier for marine shale gas exploration, whereas there has been limited systematic research on their sedimentary environment and organic matter (OM) enrichment mechanisms. Therefore, we present total organic carbon (TOC) analysis, major/trace element analyses and scanning electron microscope experiments for the Permian marine shales from the trough to determine their paleoenvironmental conditions and influencing factors of OM enrichment. The results show that the paleoclimate changed from dry climate to humid and warm climate (P3w1 [the first member of the Wujiaping Formation]) and semi‐humid to semi‐arid climate (P3w2 [the second member of the Wujiaping Formation]) and P3d‐I (Dalong Formation‐I) and then to arid climate again during the shale deposition period from the P2g (Gufeng Formation) to the P3d‐II. The shales with the highest TOC contents (TOC > 3%, P3d‐I and P2g), lower TOC contents (TOC < 1%, P3w1 and P3w2) and higher TOC contents (1% < TOC < 2%, P3d‐II) were formed under the control of anoxic environment and high paleoproductivity, oxic‐suboxic environment and high paleoproductivity, anoxic‐euxinic environment and lower productivity, respectively. Only appropriate sedimentation rates promote OM enrichment. Terrestrial input, paleoclimate, volcanic activity and hydrothermal upwelling mainly indirectly affect OM accumulation by influencing paleoproductivity. The degree of redox conditions is the primary factor affecting OM enrichment, followed by paleoproductivity. Nonetheless, anoxic to euxinic environments are most appropriate for OM preservation. Weak volcanic activity can boost paleoproductivity, but severe volcanic activity might introduce excessive harmful compounds that limit organism survival, resulting in a fall in paleoproductivity. Additionally, element P brought by volcanic ashes doesn't contribute to OM accumulation.

Isotope Encoded chemical Imaging Identifies Amyloid Plaque Age Dependent Structural Maturation, Synaptic Loss, and Increased Toxicity.

It is of critical importance to our understanding of Alzheimer's disease (AD) pathology to determine how key pathological factors are interconnected and implicated in nerve cell death, clinical symptoms, and disease progression. The formation of extracellular beta-amyloid (Aβ) plaques is the major pathological hallmark of AD and Aβ has been suggested to be a critical inducer of AD, driving disease pathogenesis. Exactly how Aβ plaque formation begins and how ongoing plaque deposition proceeds and initiates subsequent neurotoxic mechanisms is not well understood. The primary aim of our research is to elucidate the biochemical processes underlying early Aβ plaque formation in brain tissue. We recently introduced a chemical imaging paradigm based on mass spectrometry imaging (MSI) and metabolic isotope labelling to follow stable isotope labelling kinetics (iSILK) in vivo to track the in vivo build-up and deposition of Aβ. Herein, knock-in Aβ mouse models (App NL-F ) that develop Aβ pathology gradually are metabolically labeled with stable isotopes. This chemical imaging approach timestamps amyloid plaques during the period of initial deposition allowing the fate of aggregating Aβ species from before and during the earliest events of plaque pathology through plaque maturation to be tracked. To identify the molecular and cellular response to plaque maturation, we integrated iSILK with single plaque transcriptomics performed on adjacent tissue sections. This enabled changes in gene expression to be tracked as a function of plaque age (as encoded in the Aβ peptide isotopologue pattern) distinct from changes due to the chronological age or pathological severity. This approach identified that plaque age correlates negatively with gene expression patterns associated with synaptic function as early as in 10-month-old animals but persists into 18 months. Finally, we integrated hyperspectral confocal microscopy into our multiomic approach to image amyloid structural isomers, revealing a positive correlation between plaque age and amyloid structural maturity. This analysis identified three categories of plaques, each with a distinct impact on the surrounding microenvironment. Here, we identified that older, more compact plaques were associated with the most significant synapse loss and toxicity. These data show how isotope-encoded MS imaging can be used to delineate Aβ toxicity dynamics in vivo. Moreover, we show for the first time a functional integration of dynamic MSI, structural plaque imaging and whole genome-wide spatial transcriptomics at the single plaque level. This multiomic approach offers an unprecedented combination of temporal and spatial resolution enabling a description of the earliest events of precipitating amyloid pathology and how Aβ modulates synaptotoxic mechanisms.

Depositional characteristics in the Lower Congo Basin during the Cenomanian-Turonian stage: Insights from fine-grained sedimentary rocks

The Cenomanian-Turonian (C-T) stage, marked by extensive black shales and Oceanic Anoxic Event 2 (OAE 2), is pivotal for deciphering paleoceanographic conditions and the main drivers of hydrocarbon formation. Despite its significant oil and gas potential, the Lower Congo Basin (LCB) in central West Africa, particularly during the C-T stage (Likouala Formation), has been severely understudied, primarily due to limited exploration and a historical preference for other basins. Therefore, understanding the depositional characteristics of the C-T stage in the LCB is essential for elucidating paleoceanographic conditions, evaluating hydrocarbon potential and interpreting environmental changes. Due to the limited availability of published data and samples, we employed a targeted and integrated geological analysis to gain comprehensive insights, encompassing logging, lithofacies identification, thin-section observations, grain size measurements, and geochemical analyses (major, trace, and rare earth elements), to provide a cohesive and confirmatory assessment. Utilizing relative sea-level curves and geochemical indicators, and by comparing with other relevant basins, this study preliminarily identified OAE 2 stratigraphic intervals and attempted to discuss the impact of OAE 2 on organic matter enrichment in the LCB. The results indicate that, during the C-T stage, the LCB featured a restricted sea bay environment with limited terrestrial input and anoxic waters. Multiple geochemical proxies suggest that relative sea-level changes significantly affected paleoproductivity, thereby influencing organic matter enrichment. During the depositional period of Lower Likouala Formation (LLF), a relative sea-level drop resulted in weakly reducing conditions in a marginal restricted sea bay environment, leading to low primary productivity. Conversely, during the depositional period of Upper Likouala Formation (ULF), enhanced aeolian input and sea-level rise increased nutrient supply from the open ocean. This led to elevated surface marine productivity and intensified reducing conditions in the water column, forming a marginal semi-restricted sea bay environment. Enhanced reducing conditions within the lower stratigraphic intervals of the ULF are likely consequences of OAE 2. However, the marginal restricted sea bay environment and limited water exchange may have constrained the enhancement of paleoproductivity by OAE 2. These insights not only significantly enhance our understanding of the organic-rich fine-grained sedimentary rocks in the LCB during the C-T stage, but also contribute to a broader comprehension of the South Atlantic's paleoceanographic conditions and the interplay between regional geological processes and global climate events during the C-T stage.

Simulation of Dendrite Growth with a Diffusion-Limited Aggregation Model Validated by MRI of a Lithium Symmetric Cell during Charging

Lithium metal batteries offer high energy density but are challenged by dendrite growth, which can lead to short circuits and battery failure. Multiple models with varying degrees of accuracy and computational cost have been developed to understand and predict dendrite growth. This study presents a simple model to simulate macroscale dendrite growth on lithium metal electrodes. The model uses a 3D single-particle Diffusion-Limited Aggregation (DLA) algorithm with an electric field bias to simulate dendrite growth. The electric field bias was introduced into the model with an important parameter, namely the biasing factor c, which determines the balance between diffusion and electric field effects. Before performing the simulation with the proposed model, the dendrite growth in a lithium symmetric cell during charging was measured by sequential 3D magnetic resonance imaging (MRI). These data were then used to validate the simulation, as the dendrite structure in each measured MRI time frame was used a starting point for a new simulation, the results of which were then validated with the measured dendrite structure of the next time frame. The best agreement between the simulated and measured dendrite structures using the overlap and displacement of deposition sites metrics was obtained at the biasing factor c = 0.7. This agreement was also good in terms with the fractal dimension of the dendrite structures. The proposed method offers a simple, accurate, and scalable framework for predicting dendrite growth over long deposition periods, making it a valuable tool for studying dendrite suppression under real-world battery charging conditions.

In Situ Synthesis and Characterizations of a Strontium-Substituted Dicalcium Phosphate Anhydrous/Hydroxyapatite Biphasic Whisker and Its Properties Evaluation.

Dicalcium phosphate anhydrous (DCPA) presents good biomineralization ability, the strontium element is known for superior bone affinity, and a whisker possesses good mechanical strength; all these are beneficial for improving the drawbacks of hydroxyapatite (HAP) like weaker mechanical properties, poor biomineralization, and slower degradation/absorption. Therefore, a homogeneous precipitation was adopted to synthesize Sr-substituted and DCPA and HAP coexisting whiskers. The composition, structure, and morphology based on urea dosage and substitution content were characterized, and the roles of DCPA, Sr, and whisker shape were investigated. It turned out that Sr-DCPA/HAP biphasic products contained about 19% DCPA and 81% HAP, and both phases occupied the outer and inner parts of the whisker, respectively. Increasing the urea dosage made the morphology transform from a sea urchin shape to fiber clusters and then whiskers, while Sr substitution brought the whisker back to the porous microsphere shape. Only 5% of Sr content and 15 g of urea could maintain the whisker shape. Sr could promote the proliferation of MC3T3-E1 cells even at a higher extract concentration of 10 mg/mL. The cells stayed in a healthy state whether cocultured with the whisker or the microsphere. The unstable DCPA combined with the decreased crystallinity brought by Sr doping contributed to shortening the apatite deposition period to within 7 days. The whisker morphology enhanced the compressive strength of acrylic resin, and the apatite layer helped to reduce the strength loss during soaking. The Sr-DCPA/HAP biphasic whisker with enhanced overall properties possessed more promising potential for biomedical application.

Sedimentary record of primary productivity changes in a crater lake in Northeast China since the Last Glacial Maximum

High-resolution primary productivity records are valuable for identifying lacustrine ecosystem degradation in the context of long-term climatic variability. In this paper, we analyse primary productivity changes in a seasonally ice-covered crater lake (Lake Tuofengling) in northeast China since the Last Glacial Maximum using biogenic silica content and the carbon preference index of short-chain n-alkanes as proxies. Results show that primary productivity was lower during the cold and dry glacial period, whereas it was higher during the warm and humid Holocene. During the last deglaciation, primary productivity experienced a ∼ 1.5-kyr lagged response to Bølling-Allerød warming, and multiple oscillations during the Younger Dryas. Additionally, the peak productivity of the entire profile also occurred during this period. These fluctuations and the highest primary productivity are suggested to be the result of the combined influences of increased summer temperatures and regional permafrost melting. The current state of primary productivity in Lake Tuofengling is moderate but has been increasing since the abrupt increase in diatom productivity after ∼3 ka B.P. This stage is associated with increased dust deposition and longer ice-free periods under winter-warming conditions. We suggest that longer seasonal stratification under the current warmer winters and increased nutrient concentrations caused by decreased lake level will increase the risk of lake ecosystem degradation in the future.

The characteristics of volcanic lithofacies and volcanic reservoirs in the Permian Jiamuhe Formation, Southern Zhongguai Rise, Junggar Basin, NW China

The southern Zhongguai Rise has gained wide attentions due to its commercial hydrocarbon discoveries from volcanic deposits in Jinlong Oilfield. The integrated analysis of geological and geophysical data assist in determination and depiction of volcanic lithology and volcanic facie, characterization of volcanic reservoirs as well as discussion of constrains on volcanic lithology/lithofacies. The conclusions suggest that two types of volcanic lithology, including volcaniclastic rocks and silicic moltenlava, can be identified based on cores. In addition, two types of volcanic lithofacies can be delineated according to cores and wireline responses. The explosive facies are mainly developed in early depositional period while the effusive facies are developed through depositional period. Furthermore, the reservoir space predominantly consists of pores and fractures according to thin sections. The physical property varies from time to time. That is, porosity distribution varies slightly. In contrast, permeability distribution varies significantly. The volcanic reservoirs can be generally attributed to high-porosity and low-permeability reservoirs no matter in volcaniclastic rocks or silicic molten lava. The volcanic lithofacies, facies distribution, diagenism and paleogeomorphology exserts controls on physical property and reservoir performance of volcanic reservoirs together.

Analysis of structural, mechanical, and magnetic properties of electroplated NiAg thin films synthesized at different deposition time

By changing the electroplating deposition duration, such as 15, 30, 45, and 60 minutes, the NiAg thin films have been synthesised by electrodeposition on copper substrate at a uniform current density of 1 A/dm2 . The NiAg thin films were adhered to the substrate at a consistent electrolytic solution temperature of 30°C, and the created electrolyte's pH was maintained within a range of 7 to 8. EDAX, XRD, and SEM techniques have all been used to investigate the structural investigation of electrodeposited NiAg thin films. The FCC crystal structure can be seen by the X-ray diffraction analysis pattern, which indicates that the average crystalline size of the NiAg-coated thin films was between 31 and 64 nm.Images of coated thin films taken with a scanning electron microscope show that, even with longer deposition times, the surface morphology of electrodeposited NiAg thin films is consistent. The Vibrating Sample Magnetometer (VSM) examination was used to investigate the magnetic characteristics. With a greater saturation magnetization of 7.6930 × E-3 emu/cm3 and a lower coercivity of 92 Oe, the NiAg film deposited at 15 minutes shows a better soft magnetic nature. According to the electrochemical analyses of plated NiAg thin films, the NiAg film coated at the 60 -minute deposition period showed the lowest corrosion rate, measuring 0.047286 mm/year with a polarization resistance of 3900.9 Ω. NiAg thin films' mechanical and magnetic characteristics make them suitable to produce MEMS and NEMS based devices.

Sedimentary Reservoir Characteristics of Fuyu Oil Formation in the Middle of Fuxin Uplift, Southern Songliao Basin

Currently, the Fuyu reservoir in the middle of the Fuxin uplift, located in the southern Songliao Basin, is in a high water cut development stage. The understanding of this reservoir is limited, and the distribution of favorable reservoirs remains unclear, necessitating detailed reservoir characterization. This study employs a combination of well and seismic technologies to accurately depict the sedimentary and reservoir characteristics of the Fuyu oil reservoir. By conducting detailed correlations of oil zones, a regional high-resolution isochronous stratigraphic framework is established. The division of sedimentary microfacies enables fine characterization of single sand bodies, identifying channel boundaries, clarifying lateral connectivity, and detailing the vertical contact relationships of sand bodies across different deposition periods. The results demonstrate that root-mean-square amplitude and total energy metrics effectively correspond to sand bodies in the study area and can be used to analyze sand body distribution. Provenance is primarily from the southwest to the northeast, with shallow deltas predominantly developed. Delta plain subfacies are found in zones 4-12, while delta front subfacies are in zones 1-3. Microfacies types mainly include the main distributary channel, distributary channel sides, crevasse splay, overbank sand, and underwater distributary channels. The main distributary channel reservoirs exhibit the best physical properties, with porosity ranging from 20-25%, while sand bodies at the sides of distributary channels reach 15-20%. Predicted favorable areas are mainly located at the intersections of distributary channels and structural highs, where drilling is likely to yield high oil flow.

Paleogeographic reconstruction and sedimentary evolution of tidal-dominated estuarine depositional systems: Insights from the campanian M1 sandstone formation, Oriente Basin, Ecuador

The Oriente Basin is a back-arc basin located east of the Ecuadorian Andes in South America. Evidence suggests that during the Cretaceous period, the basin's margins received a terrigenous shallow marine sedimentation. Due to regional variations in accommodation and depositional controlling factors near a shoreline, the sedimentary environments in the fluvial-marine transitional zones exhibit considerable variability. In this study, we analyzed the sedimentological characteristics of the M1 Sandstone Formation unit (∼83 Ma-72 Ma), which comprises a set of ancient estuarine deposits preserved in the northern part of the basin. We quantified the impact of mixed hydrodynamic processes on the distribution of tidal-dominated estuarine facies and discussed the development conditions and evolutionary processes of an estuarine formation under the background of persistent transgression. Core, well log, and seismic data provide evidence for reconstructing the tidal-dominated estuarine environment. In the core section, we identified 14 lithofacies and 7 major facies association types. The frequent occurrence of sedimentary structures associated with tidal currents indicates that tidal processes extensively reworked the deposits. The spatial distribution trends of facies associations reveal the evolution of mixed hydrodynamic conditions dominated by tidal processes in the estuary and allow us to divide the M1 Sandstone Formation into four depositional periods: the initial development, rapid development, decline, and the post-infilling open coast tidal flat development periods. Furthermore, through a systematic analysis of hydrodynamic conditions and sediment distributions, we identified multiple depositional centers in the tidal-dominated estuary influenced by different hydrodynamic processes. These correspond to the upstream fluvial-dominated tidal point bar depositional region, the middle mixed-energy depositional interaction zone, and the downstream tidal-dominated tidal sand bar depositional region. In these regions, the substantial accumulation of sandy deposits, represented by tidal sand bars, reflects the high accommodation space characteristic of tidal-dominated estuaries. Our findings indicate that the slow subsidence of a broad and gently sloping coastal topography, stable material transport, and sea level change dominated by marine transgression ensured the necessary accommodation for the development of the estuary in the M1 Sandstone Formation. The sedimentological study of the M1 Sandstone Formation provides a case for understanding the sedimentary evolution in fluvial-marine transitional zones.

Investigation into temporal changes in the human bloodstain lipidome.

Bloodstains are crucial pieces of physical evidences found at violent crime scenes, providing valuable information for reconstructing forensic cases. However, there is limited data on how bloodstain lipidomes change over time after deposition. Hence, we deployed a high-throughput high-performance liquid chromatography-mass spectrometry (HPLC-MS) approach to construct lipidomic atlases of bloodstains, whole blood, plasma, and blood cells from 15 healthy adults. A time-course analysis was also performed on bloodstains deposited for up to 6months at room temperature (~ 25°C). The molecular levels of 60 out of 400 detected lipid species differed dramatically between bloodstain and whole blood samples, with major disturbances observed in membrane glycerophospholipids. More than half of these lipids were prevalent in the cellular and plasmic fractions; approximately 27% and 10% of the identified lipids were uniquely derived from blood cells and plasma, respectively. Furthermore, a subset of 65 temporally dynamic lipid species arose across the 6-month room-temperature deposition period, with decreased triacylglycerols (TAGs) and increased lysophosphatidylcholines (LPCs) as representatives, accounting for approximately 8% of the total investigated lipids. The instability of lipids increased linearly with time, with the most variability observed in the first 10days. This study sheds light on the impact of air-drying bloodstains on blood components at room temperature and provides a list of potential bloodstain lipid markers for determining the age of bloodstains.

Source-to-sink processes and genetic mechanism of progradational and lateral accretion submarine fans in the Qiongdongnan Basin, South China Sea

Submarine fan reservoirs are important accumulation zones for oil, gas, and natural gas hydrates, offering significant potential for hydrocarbon exploration. During the deposition period of the Sanya Formation in the southern part of the Changchang Sag of the Qiongdongnan Basin, a large submarine fan developed. However, the internal structure, source-sink system, and formation mechanism of this fan remain poorly understood, posing significant challenges to exploration in this area. This paper examines the source-to-sink sedimentary processes and deposition of submarine fans, using the Changchang Sag, in the Qiongdongnan Basin in the Northern South China Sea, as an example, which will provide valuable general guidance for deep water oil and gas exploration. Based on the theories of seismic stratigraphy and seismic sedimentology, this paper utilizes techniques such as seismic facies analysis, seismic attribute optimization, paleogeomorphology reconstruction, and source-to-sink sedimentary system analysis to analyze the 3D seismic data of the study area. Research indicates that the Sanya Formation in the Changchang Sag of the Qiongdongnan Basin comprises three depositional units: submarine fan, feeder channel, and Semi-deep marine to deep marine mudstone. The submarine fan is a fan formed by the coupling and convergence of submarine fans sourced from the southwest and southeast. Internally, it is divided into three sub-facies: the proximal fan of the sand-rich submarine fan, the main body of the sand-rich submarine fan lobes, and the distal lobes of the sand-rich submarine fan. The submarine fan sourced from the southwest extends nearly north-south and is primarily fed by sediment transported through three large, banded ancient valleys. The sedimentary filling is characterized by three-phase progradation. The submarine fan sourced from the southeast extends nearly east-west and is primarily fed by sediment transported through a single large, banded ancient valley. The sedimentary filling is characterized by two-phase lateral accumulation. During the deposition period of the Sanya Formation, certain areas of the southern uplift belt were exposed for extended periods and subjected to weathering and erosion. Sediments are transported to large ancient valleys through small supply channels. A large number of sediments were transported to the southern slope of the Changchang sag through the provenance channel system such as large ancient valleys and slope belts and deposited in the center of the sag. These make up a complete system of large ancient uplifts and submarine fan source-to-sink sedimentary systems.The sedimentary model is a lobed submarine fan controlled by semi-restricted ancient valleys and expansive basins.

Analysis of Soot Deposition Effects on Exhaust Heat Exchanger for Waste Heat Recovery System

This study investigates the thermal–hydraulic behavior and deposition characteristics of a shell and tube exhaust heat exchanger using a CFD-based predictive model of soot deposition. Firstly, considering the influences of thermophoretic, wall shear stress, and other deposition and removal mechanisms, a predictive model is developed for long-term performance of heat exchangers under soot deposition. Then, the variations in exhaust heat exchanger performance during a 4 h deposition period are simulated based on the model. Subsequently, the variation of deposition distribution and different deposition velocities are also evaluated. Finally, an analysis of the long-term performance of the exhaust heat exchanger under varying gas velocities and temperature gradients is conducted, revealing the performance variations under all engine-operating conditions. Results show that the deterioration in normalized relative j/f1/2 varies from 5.26% to 24.91% under different work conditions, and the exhaust heat exchanger with high gas velocity and low temperature gradient exhibits optimal long-term performance.

Spatial and Temporal Distribution of Igneous Sills in the Central Tarim Basin and Their Geological Implications

Interpretation of the seismic reflection profiles associated with borehole data from the petroleum industry offers a novel way to study sill emplacement in sedimentary basins. This study uses this approach to reveal the intrusive part of the Tarim Large Igneous Province (LIP) within the basin, which has not been systematically reported. A large number of igneous intrusions (sills) are identified in the sedimentary layers of the Central Tarim Basin. The burial depth of the sills is 6–8 km, and they are mainly located within the upper Ordovician strata. According to their seismic facies and drilling data, it is inferred that they are dolerite sills. Based on the uplift of the overlying strata above the intrusions, it is concluded that the sills were mainly formed during the depositional period of the middle Permian Kupukuziman Formation and Kaipailezike Formation (early stage), with a few formed during the depositional period of the upper Permian strata (late stage). It is likely that these two stages of sill intrusion correspond to the main basaltic eruptions within the basin and the mafic dike emplacement in the Bachu area of the Tarim LIP, respectively. The study suggests that that the dolerite sills reported in this study are also an important component of the Permian Tarim LIP.

A study on the accumulation model of the Santos basin in Brazil utilizing the source–reservoir dynamic evaluation method

The exploration potential within deep-water petroliferous basins holds great promise for oil and gas resources. However, the dearth of geochemical and isotopic data poses a formidable challenge in comprehending the intricate hydrocarbon charging processes, thereby impeding the comprehensive understanding of hydrocarbon accumulation mechanisms and models. Consequently, the establishment of robust source–reservoir relationships in deep-water petroliferous basins represents a pivotal challenge that significantly influences the exploration strategies and the comprehension of hydrocarbon enrichment dynamics within such basins. In this study, we introduce a novel approach, termed the “source–reservoir dynamic evaluation method,” tailored to investigate reservoir accumulation models in deep-water petroliferous basins. This method uses basin simulation technology to recover the thermal evolution history and hydrocarbon generation and expulsion history of source rocks, and on this basis delimits the hydrocarbon kitchen range. At the same time, the maturity of source rocks corresponding to crude oil and natural gas in typical reservoirs is calculated. Then, when the thermal evolution degree of source rocks adjacent to the reservoir reaches this maturity, the corresponding geological period is the main charging period of hydrocarbon. As a typical deep-water petroliferous basin, the Santos Basin in Brazil has abundant oil and gas reservoirs under the thick salt rock, but there are still some fundamental problems such as unclear oil–gas accumulation process and model. Therefore, in this paper, the main charging periods of typical hydrocarbon reservoirs are determined based on the internal relationship between the thermal evolution history of the main source rocks and the maturity of crude oil and natural gas, and then the hydrocarbon accumulation process is analyzed and the dynamic accumulation model is established. Finally, the favorable prospecting direction is pointed out. The results show that the oil and gas in the Barra Velha Formation in the Santos basin are mainly derived from the Itapema Formation lacustrine shale source rock, and the source rock is mainly developed in the Eastern Sag of the Central Depression, and its main hydrocarbon generation period is from the deposition period of Florianopolis Formation to the deposition period of Santos Formation. The main hydrocarbon expulsion period was from the deposition period of the Santos Formation to the Early deposition of the Iguape Formation. The oil and gas in the Barra Velha Formation were mainly charged from the Late deposition period of the Santos Formation to the Early deposition period of the Iguape Formation. During this period, the hydrocarbon migrated vertically along the normal fault formed in the rift period to the trap of the adjacent inheritance structural highs and accumulated in the reservoir, which was dominated by the accumulation model of the “lower generation-upper reservoir-salt cap”. Since the Barra Velha Formation has the characteristics of near-source accumulation, based on the hydrocarbon expulsion center and hydrocarbon expulsion intensity of the source rock of the Itapema Formation, the distribution ranges of 85% and 50% Pre-salt accumulation probability in the Santos basin were calculated by using the quantitative analysis model of the hydrocarbon distribution threshold. It is suggested that the next oil and gas exploration should be carried out in the paleo-structural highs and slope of Class I favorable area (the hydrocarbon accumulation probability is more than 85%) and Class II favorable area (the hydrocarbon accumulation probability is 85–50%).

Formation temperature of microcrystalline dolomite in oil-rich black shale: Implications for hydrocarbon accumulation in a volcanic-lacustrine rift basin

Lacustrine microcrystalline dolostones in the ancient records have been commonly interpreted as of an evaporitic origin, on the basis of their numerous occurrences in modern evaporative shallow lakes. This interpretation obscures the forming mechanisms of dolostones formed in a deep lacustrine setting, where dolostones interbedded with shale become a focus of hydrocarbon source rocks in recent years. In this study, an alternative non-evaporitic origin of dolomite is interpreted for a Permian lacustrine laminated dolostone. The dolostones are thinly intercalated with tuffaceous shales and composed mainly of volumetrically abundant, low-ordered, subhedral to euhedral, microcrystalline dolomites with a variable amount of pyroclastics. Evidence for evaporation (e.g., the presence of halite, gypsum and shrinkage cracks) and typical methanogenic microfossils is absent. Instead, our dolostones are unevenly and locally distributed as thin beds or lenses and intercalated with tuffaceous shale and have a formation temperature ranging from 31.4 to 73.8 °C, as estimated from dolomite clumped oxygen? isotope thermometry. In addition, the dolostones have a87Sr/86Sr ratio similar to that of the mantle (0.705154 on average) and extremely negative δ18O (−2.9‰ to −24‰) and positive δ13C (5.1‰–10.8‰) values. A lateral trend of increasing formation temperature of the dolostone toward the volcanic center correlates with the trends of: 1) an increasing amount of pyroclastics, euhedral dolomite crystals, Fe, and TOC, and an increasingly positive δEu value, and 2) decreasing values of 87Sr/86Sr and δ18O. The correlation suggests that a local temperature increase and frequent elemental (Fe and Mg) cycling between the conditions of dolomite supersaturation and undersaturation, which are controlled by episodic volcanic-hydrothermal activities are the causes for dolomite nucleation and growth, resulting in the formation of massive dolostone during deposition and shallow burial. The process also affected organic matter accumulation and local transformation to immature or early mature hydrocarbon during deposition and early burial. The results establish a volcanism-controlled temperature range for primary dolomite nucleation and growth, as well as hydrocarbon generation in a deep lake environment during the period of deposition and early burial, and provide insights on shale oil exploration in petroliferous rift basins.

Submarine canyon development controlled by slope failure and oceanographic process interactions

The southeastern Australian margin hosts a series of submarine canyons. Although the origin and evolution of canyons within the northwestern segment of the margin is relatively well studied, their quantitative morphology, interaction with longshore drift currents and slope failure remain poorly understood in the southeastern region. In this study, high-resolution bathymetry and 3D seismic reflection datasets revealed five main submarine canyons present in the central offshore Otway Basin. The canyons have V-shaped, evolving to U-shaped morphology downslope with sedimentary infill characterized by medium–high amplitudes, recognizable stratal pattern and localized chaotic seismic reflections. Analysis reveals these canyons were initiated by retrogressive slope failure on the continental slope, that once the shelf edge was reached and subsequently incised, development of the canyon heads was influenced by the shelf parallel Zeehan Current, active on the continental shelf of the region. The heads of the shelf-incised canyons preferentially migrate northwestward and were infilled by laterally accreting sedimentary packages characterized by southeast dipping seismic reflections. These indicate an early erosive phase followed by a period of deposition, a result of the prevalent eastward flowing Zeehan Current. These results have important implications for understanding of the mechanisms that control initiation and development of submarine canyons, and their morphology, both offshore southeastern Australia, and similar settings on continental margins worldwide.

Influence of the sedimentary environment of the Wufeng-Longmaxi shale on organic matter accumulation in the Dingshan area, Sichuan Basin

The sedimentary environment and organic matter (OM) accumulation are vital indicators for shale gas exploration. However, research on deep shale gas systems is relatively limited; moreover, the exploration of deep shale gas in the southeastern Sichuan Basin has entered a period of stagnation. In this study, systematic geochemical analysis of Wufeng (WF) and the first member of the Longmaxi (Long-1) deep shale samples from the recently drilled DY7 well in the Dingshan area of the Sichuan Basin is carried out, and the longitudinal variations in major and trace elements are revealed. The differences in the WF, lower section of the Long-1 (Long-11) and upper section of the Long-1 (Long-12) shales are studied in terms of redox conditions, paleoproductivity, terrigenous detrital input, sedimentation rate and paleoclimate, and the different main controlling factors of OM accumulation for these three layers are discussed. The WF shale has a higher TOC content (mean: 5.73%), the Long-11 shale has a high TOC content (mean: 2.89%), while the Long-12 shale has a low TOC content (mean: 1.44%). For the WF shale, due to complex geological events and large fluctuations in element contents, its TOC content is poorly correlated with these indices, redox and paleoproductivity proxies have a positive association with the Long-11 shale’s TOC content, but negatively correlated with terrigenous input and sedimentation rate indices. The formation of these two sets of organic-rich shales (TOC > 2%) is jointly controlled by good preservation conditions. In contrast, the TOC content of the WF shale is higher than that of the Long-11 shale as the result that terrigenous input and sedimentation rate of the Long-11 shale represent the dilution and destruction of OM, which is different from the former. During the Long-12 depositional period, the water column experienced weak reducing conditions and low productivity, and its high terrigenous debris input further diluted the OM, leading to a low TOC content.

Investigation of microstructure, tribological, and corrosion behaviors of TiN@AISI 316 CN processed by rf plasma

In order to enhance the tribological and corrosion properties of AISI 316 substrate, rf plasma carbonitriding was involved to form a carbonitrided layer on AISI 316 base substrate. The deposition of TiN top layer was executed engaging titanium nitride target in argon plasma atmosphere. All the deposition working parameters were reserved to be constant excepting the deposition period that was altered from 4 to 20 min. The effect of TiN top layer thickness on the structure, tribological and electrochemical characteristics of TiN@AISI 316 CN duplex treatment was explored. It was demonstrated, that the duplex coating enhanced the hardness (max: 1740 HV0.025 for TiN (1325nm)@AISI 316 CN sample) and improved the wear and corrosion resistance. Besides, the coefficient of friction is reduced to 0.12–0.2 for TiN@AISI 316 CN duplex treated samples compared with untreated AISI 316 which recorded a value of 0.47.

Mercury deposition in central China from the Last Glacial Maximum to the early Holocene recorded in an accurately-dated stalagmite

Characterization of transport pathways and depositional changes in Mercury (Hg) and their connection to climatic and environmental changes on various time scales are crucial for better understanding the anthropogenic impacts on the global Hg cycle in the Anthropocene epoch. In this study, we examined Hg variations recorded in a stalagmite from central China, covering the period from 25.5 to 10.9 thousand years ago. Our data show a marked increase in Hg concentrations during the late Last Glacial Maximum, which coincided with the period of highest dust deposition on the Chinese Loess Plateau. Hg concentrations were lower during Heinrich events 1 and 2 and the Younger Dryas but higher during the Bølling-Allerød and the early Holocene. We suggest that regional dust load, which enhances atmospheric dry deposition of Hg, is the primary factor influencing Hg deposition in central China on glacial-interglacial timescales. On millennial-to-centennial timescales, climate also plays a significant role. Warmer and wetter conditions increase vegetation, litterfall, and soil/rock weathering, which in turn boost mineral dissolution and soil erosion in the vadose zone. These processes collectively result in higher Hg concentrations in the stalagmite.