Fine-grained Components Research Articles

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

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

The characteristics of modern flood deposits in the lower reaches of a small watershed and the significance of paleo-flood identification

The mountainous region of central Shandong Province in eastern China is renowned for its high frequency of rainstorms, which often result in devastating flood disasters and have profoundly affected the evolution of local ancient civilizations. To identify ancient flood disaster events, recognizing sediment signatures via multiple indices is important. Here, we investigated the 2018 flood deposits in the Danhe River Basin and sampled short core DH2, on which the grain size, total organic matter (TOM) content, carbonate content, magnetic susceptibility (MS) and pollen were measured. The fine grain size of the flood sedimentary layer reveals that the flood energy in the alluvial plain area is usually weak. The pollen species and concentration and the tree pollen content in the flood layer are significantly greater than those in the soil layer, suggesting that the flood sediment mainly originates from the mountainous areas in the upper reaches of the river, which provides more forest vegetation information. The MS of flood deposits is lower than that of the soil layer, which is mainly related to the intensity of pedogenesis. The research results indicate that the flood sediments in the downstream floodplain areas of small watersheds are predominantly composed of fine-grained components, with characteristics of high loss on ignition, low magnetic susceptibility, high pollen abundance and diverse species. These findings establish a multi-index identification system for paleoflood sedimentation, which has important reference significance for the study of paleoflood sedimentology and hydrology.

Accumulation and migration of particulate trace metals by artificial flood event of the Yellow River: From Xiaolangdi reservoir to estuary

Reservoir construction increasingly alters the natural transport of riverine water and sediment to the sea, including the trace metals and other pollutants. In 2018, an intensive flood event and 412 million tons of sediment were released from the Xiaolangdi dam during the water-sediment regulation of Yellow River, one of the world's largest sediment releases. During the artificial flood event, the surface sediments in Xiaolangdi Reservoir (XLD) and the Yellow River estuary, suspended sediments at Lijin Station were collected. The concentration and speciation of particulate Cr, Ni, Cu, Zn, Cd and Pb, as well as the major geochemical composition were analyzed, to characterize the behaviors of the metals from the reservoir to estuary mixing zone, and elucidate the controlling mechanisms. The results showed that for exogenous phases, Cr, Ni, Cu and Zn were likely bound to the FeMn oxides, whereas Pb and Cd were mainly adsorbed in the carbonates. The trace metals in XLD were stably combined with fine-grained bottom sediments at high concentrations before dam release. During the delivery from reservoir to downstream channel, the binding of Cr, Ni and Cu with FeMn oxides was markedly enhanced. Pb and Cu showed obvious migration from carbonates to FeMn oxides, and Cd and Pb were even released into the water. The accumulation and migration of trace metals were controlled by the adsorption of fine-grained components, especially FeMn oxides and carbonates, and influenced by the oxidizing processes. After entering the estuary, the trace metals were greatly scavenged by reservoir-sourced fine particles, tended to bound to organic matter affected by the reducing environment. Our results suggest that dam regulation and artificial flood events will likely alter the existing forms and redox state of trace metals and the potential environmental effects should be considered.

CrossWaveNet: A dual-channel network with deep cross-decomposition for Long-term Time Series Forecasting

Many real-world applications require predicting data changes over a longer period, such as early warning for energy consumption and long-term planning for transportation. Long-term Time Series Forecasting (LTSF) demands models with high predictive capability. Recently, transformer-based models have achieved notable success in LTSF. However, the inherent nature of the permutation-invariant self-attention mechanism in Transformers can lead to the loss of certain temporal patterns. Therefore, we propose a dual-channel network with deep cross-decomposition for LTSF, called CrossWaveNet. In order to better capture long-term dependencies, unlike the complex network structure of Transformer, a simpler and more effective dual-channel network model for season and trend-cyclical is constructed. The original time series is decomposed into seasonal and trend-cyclical components simultaneously, and the dual-channel network structure is used to extract their features, respectively. This structure can improve the model’s generalization ability, which can have good results on various types of time series data. To effectively improve the accuracy of data decomposition, the moving average method is first used to obtain coarse-grained seasonal and trend-cyclical components, and then the extracted seasonal and trend-cyclical components are gradually merged into their respective channels through the dual-channel network with deep cross-decomposition, thereby obtaining fine-grained components and effectively improving prediction performance. Compared with the state-of-the-art methods in long-term forecasting, CrossWaveNet has achieved the highest prediction accuracy and significant relative performance improvement in fields such as energy, transportation, weather, and disease transmission.

ИССЛЕДОВАНИЕ ВЛИЯНИЯ ЩЕЛЕВЫХ ОТВЕРСТИЙ В ЛОПАСТЯХ ГОРИЗОНТАЛЬНОГО ЛОПАСТНОГО СМЕСИТЕЛЯ НА КАЧЕСТВО ПОДГОТОВКИ ДВУХКОМПОНЕНТНОЙ СУХОЙ СМЕСИ

The degree of uniformity of distribution in the mixture of components largely determines the qualitative characteristics of the product prepared from it. For dry mixing of components, the use of horizontal blade mixers is quite widespread in enterprises of various industries. In the competitive conditions of the operation of enterprises, it becomes necessary to develop technical solutions that allow to increase the efficiency of operating mixing equipment at enterprises in the conditions of planned repair measures. Possibility of increasing degree of homogeneity of fine-grained mixture in horizontal blade mixer when through slot holes are made in blades is considered. Using a known software product, imitated simulations of dry mixing processes of two fine-grained components in models of a mixer body with different blade designs are performed. To study the mixing process, the method of mathematical planning of the experiment is used. Researches of obtained regression dependence characterizing change of coefficient of heterogeneity of two-component dry mixture depending on number of slit holes and their width are carried out, areas of rational values of studied parameters are established. State of mixture in mixer housings is compared with slotted holes in blades and without holes. It has been found that with steady state mixing processes, the mixture in the mixer body model with slotted holes in the blades has a more uniform particle distribution. The heterogeneity factor characterizing the quality of this mixture is less than that of the mixture in the model of a body with blades without holes.

Migration of Salt Ions in Frozen Hydrate-Saturated Sand: Effect of Silt and Clay Particles

Permafrost composed of sand with silt and clay components may store stable and metastable gas hydrates, which can lose stability under a flux of dissolved salts from natural or production-related solutions (seawater, brines from cryopegs, drilling fluids, etc.). The flux of salt ions is controlled externally by temperature and pressure as well as by the salinity of solutions and the properties of fine-grained (<0.05 mm) components in permafrost. The effect of silt and clay percentage and mineralogy (kaolinite or montmorillonite) on the patterns of salt and water transport and the related dissociation of pore gas hydrates in frozen sand is studied in laboratory experiments. The experiments are conducted in conditions that can maintain the self-preservation of gas hydrates: a constant negative temperature of −6 °C and a pressure of 0.1 MPa. Sediments with higher clay percentages show slower migration and accumulation of salt ions and the higher critical salt concentration required for the onset of gas hydrate dissociation. The flux of Na+ to sand samples containing montmorillonite is lower than to those with kaolinite. On the other hand, salt migration and hydrate dissociation are faster in sand with higher silt contents. The experimental results form the basis for a generalized model of main mechanisms that drive salt transport in frozen hydrate-bearing sediments interacting with saline solutions.

Stronger and tougher nanosized dense ceria-doped tetragonal zirconia polycrystals by sinter-HIP

Ceria-doped tetragonal zirconia polycrystal (Ce-TZP) ceramics possess significant toughness and aging resistance, while their strength is relatively limited due to the high tendency of grain growth, which has long hindered their versatile applications. This work demonstrates an effective method to combine stereolithography with pre-sintering and hot isostatic pressing (HIP) to obtain dense Ce-TZP ceramics with a reduced grain size of about 420 nm. In addition to the contribution of smaller grains, the Ce-rich phase Ce0.75Zr0.25O2 precipitates at the grain boundaries during HIP hinders grain growth and strengthens the grain boundaries, together leads to a transgranular-dominant fracture mode. As a result, the achieved Ce-TZP ceramic simultaneously reaches a high flexural strength of 770.90 ± 76.06 MPa and an excellent fracture toughness of 11.96 ± 1.31 MPa·m1/2, which are 48% and 29% higher, respectively, compared to the pressureless-sintered samples. This method is expected to enable broader applications of pure Ce-TZP ceramics and to be further extended for designing and manufacturing densified and fine-grained components with complex structures.

Controls on the accumulation of Early Cretaceous organic-rich fine-grained deposits in a mixed marine siliciclastic-carbonate distal settings of the Neuquén Basin, central-western Argentina

Deposition of black shales occurred under specific conditions that need to combine in a precise way the rate of production and the rates of destruction and dilution of organic matter. Whereas good progress has been made in the determination of the role of production and destruction of organic matter, the role of dilution of the organic components still remains comparatively understudied. In mixed siliciclastic-carbonate marine systems, the dilution of organic matter by non-organic components could be detrital and/or biogenic in origin, adding more complexity to the understanding of these particular types of black shales. In the present contribution, we studied the mixed siliciclastic-carbonate distal deposits of the late Hauterivian Agua de la Mula Member (Agrio Formation) in the Neuquén Basin. Through a combination of sedimentological, petrographic, SEM, and geochemical analyses we define the origin of the fine-grained components, reconstruct the environmental evolution, and determine the role of the production, preservation, and dilution of the organic matter. The results indicate that the unit is predominantly composed of calcite (>47%), whereas illite is the major component among the clay minerals. Thin sections and SEM studies suggest that the carbonate fraction is dominantly composed of nannofossils, i.e. biogenic in origin, and subordinately micarbs (diagenetic, but with a potential biogenic precursor). Thus, the composition of the distal deposits is mostly controlled by the input of detrital illite. The organic geochemistry and XRF data reveal that the most appropriate conditions for the accumulation of organic matter are the transgressive intervals, near the base, with a predominant effect of the rate of the production over the preservation. On the other hand, the dilution of organic matter is mainly driven by the rate of production of biogenic calcite. Interestingly, previous studies showed that in more proximal settings (but still offshore to basin realms) the dilution is controlled by siliciclastic components. Finally, organic geochemistry suggests that most of the organic matter produced is marine in origin (type II), but towards the top of the section it switches to mixed marine and terrestrial (type III to IV), likely related to a progradation of the shallower system and the consequent increase in the input of terrestrial-derived components.

Deep Unsupervised Hashing with Latent Semantic Components

Deep unsupervised hashing has been appreciated in the regime of image retrieval. However, most prior arts failed to detect the semantic components and their relationships behind the images, which makes them lack discriminative power. To make up the defect, we propose a novel Deep Semantic Components Hashing (DSCH), which involves a common sense that an image normally contains a bunch of semantic components with homology and co-occurrence relationships. Based on this prior, DSCH regards the semantic components as latent variables under the Expectation-Maximization framework and designs a two-step iterative algorithm with the objective of maximum likelihood of training data. Firstly, DSCH constructs a semantic component structure by uncovering the fine-grained semantics components of images with a Gaussian Mixture Modal~(GMM), where an image is represented as a mixture of multiple components, and the semantics co-occurrence are exploited. Besides, coarse-grained semantics components, are discovered by considering the homology relationships between fine-grained components, and the hierarchy organization is then constructed. Secondly, DSCH makes the images close to their semantic component centers at both fine-grained and coarse-grained levels, and also makes the images share similar semantic components close to each other. Extensive experiments on three benchmark datasets demonstrate that the proposed hierarchical semantic components indeed facilitate the hashing model to achieve superior performance.

Investigating Potential Links Between Fine-Grained Components in Loess and Westerly Airflow: Evidence From East and Central Asia

Loess is a ubiquitous, silty aeolian sediment common across the semiarid to subhumid regions in the Northern Hemisphere. As such, the physical characteristics of loess sediment, such as modal grain size and quartz crystallinity index, have the potential to inform us about dust transport pathways and corresponding atmospheric circulation responsible for entrainment, transport, and deposition. In this article, we combine detailed granularity analyses and non-parametric end-member modeling with investigations of the quartz crystallinity index of three loess deposits, extending from East to Central Asia, with the aim of identifying dust transport processes and the climate subsystems responsible for them. We find marked differences in the grain size characteristics of Eastern and Central Asian loess. Given potential linkages of fine particles to the westerly jet stream, here we focused on the fine-grained end-members in the loess. The fine-grained components of the Central Asian Bishkek (BSK) and Chashmanigar (CMG) loess may be derived from individual particles carried at high altitude by major climate subsystems such as the westerlies. However, similar quartz crystallinity indexes of fine- and coarse-grained components in the Central Asian loess indicated that surface-level wind strength might influence the releases from proximal-sourced regions and abundances in the upper atmosphere for the fine particles. By contrast, the fine-grained component of the East Asian [Fanshan18 (FS18)] loess seems to yield physical similarities to the Tertiary Red Clays underlying many loess stratigraphies, and has been interpreted to relate to transport associated with the East Asian winter monsoon. It was further supported by quartz crystallinity indexes of the &amp;lt;16 μm fractions in the FS18 loess, basically consistent with those of the deserts in North China, highlighting the near-surface northwesterly winter monsoon as the dominant transport dynamics of fine-grained dust. In addition, comparisons of quartz crystallinity indexes of fine-grained components between the East and Central Asian loess also suggest that variations in fine particles within the loess might not be related to transport by the higher-level westerlies, which is in disagreement with the previous model. Therefore, our results indicate that variations in fine-grained end-members in loess are difficult to reliably document the variabilities of higher-level westerlies.

A COMPLEX DYNAMIC EMOTIONS AND WILLINGNESS TO COMMUNICATE IN THE TASK-BASED CLASSROOM INSTRUCTIONS

This study aimed to investigate the complex dynamic emotions underlying learners’ Willingness to Communicate (WtC) in the classroom interaction. Utilizing Dornyei’s (2014) Retrodictive Qualitative Modeling (RQM), we embarked with some steps: identifying learners’ archetypes, highlighting the dynamic patterns of emotions interacting to other components, and setting up signature dynamics. Eighteen participants studying English participated in two task-based instructions. Of eighteen learners of English department, we took five participants relying on their salient archetypes. We utilized K-means cluster analysis to group the learners’ archetypes that was computed by SPSS 20. Additionally, in-depth interview was carried out on the elected participants to get a thick description of the emotional states and other components underpinning L2 WtC. The results reveal twofold: (1) the participants’ dynamic patterns of emotions interacting with the classroom environment explicate the variability and fluctuation of learners’ WtC, (2) the variety of signature dynamics provided fine-grained components underlying learners’ WtC. Furthermore, the implication for further study and pedagogy is elucidated later.&#x0D; Key words: complex dynamic systems, emotions, Willingness to Communicate, Retrodictive Qualitative Modeling

Directional dark-field implicit x-ray speckle tracking using an anisotropic-diffusion Fokker-Planck equation

When a macroscopic-sized non-crystalline sample is illuminated using coherent x-ray radiation, a bifurcation of photon energy flow may occur. The coarse-grained complex refractive index of the sample may be considered to attenuate and refract the incident coherent beam, leading to a coherent component of the transmitted beam. Spatially-unresolved sample microstructure, associated with the fine-grained components of the complex refractive index, introduces a diffuse component to the transmitted beam. This diffuse photon-scattering channel may be viewed in terms of position-dependent fans of ultra-small-angle x-ray scatter. These position-dependent fans, at the exit surface of the object, may under certain circumstances be approximated as having a locally-elliptical shape. By using an anisotropic-diffusion Fokker-Planck approach to model this bifurcated x-ray energy flow, we show how all three components (attenuation, refraction and locally-elliptical diffuse scatter) may be recovered. This is done via x-ray speckle tracking, in which the sample is illuminated with spatially-random x-ray fields generated by coherent illumination of a spatially-random membrane. The theory is developed, and then successfully applied to experimental x-ray data.

FLINT: Flows for the Internet of Things

New protocols and technologies are continuously competing in the Internet of Things. This has resulted in a fragmented landscape that complicates the integration of different solutions. Standardization efforts try to avoid this problem, however within a certain ecosystem, multiple standards still require integration to enable trans-sector innovation. Moreover, existing devices require transformations to fit in an ecosystem. In this paper, we discuss several integration problems in the field of Low Power Wide Area Networks in the context of the Port of the Future and propose a new distributed platform architecture, called FLINT. FLINT is a framework to program flexible and configurable flows on a per device basis. A flow is constructed from fine-grained components, called adapters. Due to the modularity of an adapter, users can easily integrate existing software. We evaluated FLINT based on five levels of interoperability and show that FLINT can be used to interconnect non-interoperable systems and protocols on every level. We have also implemented FLINT in a container based environment and demonstrated that a basic configuration has a 99% forwarding rate of 17.500 513-byte packets per second, showing that the architecture can deliver good performance.

Impact of Typhoon Talim on surface sediment records on the East China Sea continental shelf

The East China Sea (ECS) is susceptible to summer typhoons, which play an important role in sediment transport and reworking on the continental shelf. However, because observations during typhoon passage are difficult to carry out even at present, the influence of typhoons on sedimentary records in the ECS is not fully understood. In this study, we compared the elemental compositions and grain-size distributions of surface sediments collected before and after the passage of Typhoon Talim. Through end-member modeling algorithm (EMMA) analysis, the variations in sediment composition due to the typhoon passage were characterized, and the impacts of typhoons on sediment migration, redistribution and sedimentary records on the ECS continental shelf were elucidated. Comparison of the results revealed that after the passage of Typhoon Talim, the clay distributions were generally parallel to the coastline, the sand contents in the northeast and southeast of the study area decreased, and the sorting coefficient decreased in the inner shelf mud area and increased in the relict sand area. The three-end-member model was capable of adequately reproducing all variables, and the three end members were interpreted to be the fine-grained components of river terrigenous sediments (EM1), mixed sediments (EM2), and relict sands (EM3) according to the grain-size and chemical element composition characteristics of surface sediments. Summer typhoons can interrupt the cross-shelf transport of fine-grained sediments caused by cross-shelf penetrating fronts (CPFs) and can promote exchange between fine-grained sediments and relict sands on the ECS continental shelf. Thus, summer typhoons play a vital role in retaining the mud on the ECS inner shelf and redistributing the sediments on the ECS continental shelf.

Description-based person search with multi-grained matching networks

Description-based person search aims to retrieve a person in the image database based on a description about that person. It is a challenging task since the visual image and the textual description belong to different modalities. To fully capture the relevance between person images and textual descriptions, we propose a multi-grained framework with three branches for visual-textual matching. Specifically, in the global-grained branch, we extract global contexts from the entire images and descriptions. In the fine-grained branch, we adopt visual human parsing and linguistic parsing to split images and descriptions into semantic components related to different body parts. We design two attention mechanisms including segmentation-based and linguistics-based attention to align visual and textual semantic components for fine-grained matching. To further exploit the spatial relations between fine-grained semantic components, we construct a body graph in the coarse-grained branch and exploit graph convolutional neural networks to aggregate fine-grained components into coarse-grained representations. The visual and textual representations learned by three branches are complementary to each other which enhance the visual-textual matching performance. Experimental results on the CUHK-PEDES dataset show that our approach performs favorably against state-of-the-art description-based person search methods.

When Dictionary Learning Meets Deep Learning: Deep Dictionary Learning and Coding Network for Image Recognition With Limited Data.

We present a new deep dictionary learning and coding network (DDLCN) for image-recognition tasks with limited data. The proposed DDLCN has most of the standard deep learning layers (e.g., input/output, pooling, and fully connected), but the fundamental convolutional layers are replaced by our proposed compound dictionary learning and coding layers. The dictionary learning learns an overcomplete dictionary for input training data. At the deep coding layer, a locality constraint is added to guarantee that the activated dictionary bases are close to each other. Then, the activated dictionary atoms are assembled and passed to the compound dictionary learning and coding layers. In this way, the activated atoms in the first layer can be represented by the deeper atoms in the second dictionary. Intuitively, the second dictionary is designed to learn the fine-grained components shared among the input dictionary atoms; thus, a more informative and discriminative low-level representation of the dictionary atoms can be obtained. We empirically compare DDLCN with several leading dictionary learning methods and deep learning models. Experimental results on five popular data sets show that DDLCN achieves competitive results compared with state-of-the-art methods when the training data are limited. Code is available at https://github.com/Ha0Tang/DDLCN.

Transport of fine-grained sediment in oceanic currents: Holocene supply to sediment drifts around Flemish Cap by the Labrador Current

Hemipelagic sediment on the upper continental slope is commonly transported from the adjacent continental shelf, but along-slope transport of sediment by thermohaline currents may be an important source of sediment. One such case is Flemish Cap, a promontory of the eastern Canadian continental shelf protected from direct continental sediment supply by the deep-water Flemish Pass. Pleistocene sediment drifts around Flemish Cap accumulated glacially derived sediment from the north, transported by the Labrador Current. This study determines the changing sources and controls on the accumulation of bioturbated hemipelagic sediment through the Holocene. From a set of >150 box cores in water depths of 600–1200 m, some 30 push cores, up to 55 cm long, were studied in detail for stratigraphic variation in grain size, bulk geochemistry (XRF) and detrital petrology (granule petrology and qXRD). Criteria were developed to identify trawling disturbance. Two Holocene stratigraphic units, A) almost lacking ice-rafted detritus and B) with some coarse IRD and higher detrital carbonate, correlate with similar units farther north on the Labrador Shelf and Slope. Sedimentation rates based on 26 radiocarbon dates were ~ 0.02–0.03 m/ka over much of the region below the 800 m isobath, locally reaching 0.1 m/ka in some sediment drifts, but as low as 0.01 m/ka on southeastern Flemish Cap. Where sedimentation rate was >0.03 m/ka, the record of flow vigor from the sortable silt proxy since 6 ka shows three different zones of Labrador Current flow with different timing of changes in flow vigor. The mid to early Holocene record shows that the meltwater-driven inner Labrador Current extended across the entire study area. Where sedimentation rates are lower, periods of sediment bypassing are inferred and the sortable silt record varies little. Correlation with external drivers is hampered by century-scale core resolution and sparse dating control. The distinctive abundance of dolomite rock flour in hemipelagic sediments around Flemish Cap indicates important supply from Baffin Bay icebergs during the entire Holocene, diluted prior to 6 ka by sediment from Hudson Strait and some Labrador ice streams. Baffin Bay icebergs melt preferentially in the southern Labrador Sea, dropping their load, with the fine grained component transported to the south by the Labrador Current. Similar partitioning of coarse- from fine-grained components of IRD may take place on other high-latitude outer continental margins.

Distribution and movement of heavy metals in sediments around the coastal areas under the influence of multiple factors: A case study from the junction of the Bohai Sea and the Yellow Sea

Based on the Cr, Pb, Zn, Cd, and As content and grain data from the surface sediments of 56 sampling sites in the coastal waters off the northern Shandong Peninsula, the distribution characteristics of heavy metals in sediments were analyzed, and the sources of these elements were discussed. The results show that the distributions of Cr, Pb, and Zn were similar to each other, while the distributions of As and Cd differed from the other three, with Cr, Pb, Cd, and As all showing high concentrations in the Dengzhou shoal. Cr, Pb, and Zn, which are controlled by fine-grained components of surface sediments, mainly originated from natural processes, As mainly originated from aquaculture, and Cd originated from both natural and human sources. The high concentrations of heavy metals were mostly in areas of residual current convergence and coastal current action, and the distribution of heavy metals can be well correlated to the sedimentary dynamic environment. Human activities, grain size and hydrodynamic conditions are therefore important factors that influence the distribution of heavy metals in this study area.

Spatial and temporal variability of sediment infilling and episodic rifting in the North Pearl River Mouth Basin, South China Sea

Pearl River Mouth Basin (PRMB) is a typical episodically rifting basin, and its sediment records exhibit a multistage infilling process. To build the coupling relationship between the spatial variability of tectonic movement and sediment dispersal pattern, we character the source-to-sink system distribution within continental margin and analysis their dominated factors with quantitative statistical methods. First, we identify the faults and calculate the rifting rate by interpreting the two-dimensional (2D) seismic data and zircon or apatite fission-track data (ZFT/AFT). Accordingly, based on the various trending of the rifting rate evolution, we classified rifting process episodically into three patterns: accelerated rifting decelerated rifting, and uniform rifting. Then, we integrated the data available on detrital zircon U–Pb, rare earth element, and heavy mineral assemblage to identify the responding S2S components associated with the above various rifting processes. Results show that in the first tectonic stage during the early Eocene, the sediments were mainly sourced from an intrabasin provenance area, whereas in the late Eocene to the Oligocene, the paleo-Pearl River provided the sediments to the sink area. We restore the facies association of the sink area by studying the core samples, electric well logs, and three-dimensional (3D) seismic data. During the accelerated and uniform rifting processes, coarse-grained deposited along the boundary faults, which includes the fan delta and subaqueous fans. During decelerated rifting, the depositional environment was dominated by braided channels, meandering channels, and tide-influenced channel accretion. Based on the quantitative analysis the relationship between the grain size of the sediment in each S2S segment and the rifting rate, more fine-grained components were preserved in the decelerated rifting system, while coarse-grained sediments fill the accelerated rifting depression and uniform rifting components. Furthermore, the sediment supply and relative height can influence the volume of the S2S system in the uniform rifting system. In the decelerated rifting basin, the sediment supply is the major factor associated with the development of S2S, whereas the relative height is the major factor associated with the accelerated rifting basin.

Features of terraces and the incision rate along the lower reaches of the Yarlung Zangbo River east of Namche Barwa: Constraints on tectonic uplift

Abstract Along the lower reaches of the Yarlung Zangbo River, scattered alluvium sections appear on T1 and T2 terraces. The alluvial deposits on the T1 terrace in Linduo and Ximogou and the T2 terrace in Guoguotang are composed principally of coarse-grained sand particles and rock fragments, with no observable fine-grained components. The T1 terrace alluvium section is dominated by clay and silt and occurs near the town of Dexing, and optically stimulated luminescence dating of sample from this site revealed an age of 18.2 kyear, which indicates that the incision rate of the Yarlung Zangbo River has been 4.7 mm/year since the formation of this section. On the basis of the component characteristics of terraces in Motuo County, the provenance for the terraces is probably related to the breaking of the palaeo-dammed lakes in the middle reaches of the Yarlung Zangbo River. A 430 m elevation difference still exists between the study area and the local base level downstream of the Yalung Zangbo River (Assam Plain), although this river has a strong incision capability (4.7 mm/year), which suggests that tectonic uplift remains very intense east of the Namche Barwa syntaxis.