Gravel Composition Research Articles

Determination of the long-term slip rate of a fault in a slowly deforming region based on a reconstruction of the landform and provenance

Determining slip rates is essential for assessing earthquake hazards and understanding their recurrence intervals. However, in regions characterized by slow deformation, the long intervals between seismic events present challenges in understanding the long-term seismic behavior. This study focused on the Yangsan Fault (YF) on the Korean Peninsula, which is a major active fault in a slowly deforming area. We identified paleo-surface ruptures and validated stratigraphic evidence of paleo-earthquakes by geomorphological analyses and trench surveys along the YF. Landform restoration analyses indicate a lateral offset of ~320 m, which is supported by downstream changes in gravel composition in channels that cross the YF. Our investigation into the notable changes in gravel composition within channels forming in the alluvial fan revealed sediments with compositions unlikely to originate from the current topography. Observations of the sediment composition in channels within the alluvial fan, flowing from east to west, suggest a dextral slip sense focused around the YF. The minimum slip rate for the lateral offset was calculated to be 0.38–0.57 mm/yr using a burial age of ca. 698 ka for a gravel deposit exposed in a trench wall. The results show the importance of using diverse approaches to mitigate methodological uncertainties in measuring fault displacements and ages, particularly when determining the long-term slip rate in intraplate settings.

Plio-Pleistocene drainage reorganization in the middle Yellow River of China, revealed by provenance and paleocurrent analysis of fluvial sediments

Continental-scale drainage reorganization is generally understood to result from landform evolution forced by the coupling between tectonic activity and climate change, attracting worldwide attention. Planation surfaces and river terraces constitute the most direct geomorphological archives for integrating the history of river systems and for reconstructing processes of drainage reorganization based on provenance analysis of the fluvial sediments. The Middle Yellow River has incised into the Ordos Block, which was previously levelled by a planation surface, creating the Jinshaan Gorge and linking the Hetao Basin to the north and the Fenwei Basin to the south. Multiple lines of evidence, from terraces correlation, sedimentary characteristics, and fluvial provenance, suggest that the Middle Yellow River catchment was occupied by fluvio-lacustrine systems before drainage integration, accumulating a sedimentary sequence derived from surrounding Red Clay and bedrocks during the period between 8.3 and 3.7 Ma. The planation surface was uplifted subsequently, forcing reorganization of the fluvio-lacustrine systems. Their integration resulted in the formation of the Jinshaan Gorge prior to 1.2 Ma. Numerous terraces were created during incision by the Middle Yellow River from north to south along the gorge. Our data, obtained from zircon UPb dating and lithological composition of fluvial gravels, further points to a remarkable discrepancy in provenance between the fluvio-lacustrine systems overlying the planation surface and the terraces sequence formed by the integrated Middle Yellow River, confirming the drainage reorganization process constrained by the geomorphic records.

Modeling the sediment transport capacity of rill flow using a soil-rock mixture on steep slopes

Study regionYangkeng watershed (E118°03 ', N24°57 '), one of the typical representative areas where Benggang occurs in southern China. Study focusSediment transport capacity (Tc) plays a key role in the construction of models of soil process-based erosion, and is closely related to sediment particle properties. However, few studies have been conducted on Tc using soilrock mixtures along steep slopes. This study investigated the impacts of gravel content and gravel composition on Tc using soilrock colluvial deposits in a steep flume. New hydrological insights for the regionTc increases with the increase of gravel content and proportion of large gravel (5–10 mm), and can be simulated by slope steepness, unit flow discharge, gravel mass content and gravel composition (R2 =0.904; NSE=0.911). The mean weight diameter (MWD) can be used as a sediment characteristic parameter to simulate Tc, and the flow velocity, Reynolds number and stream power are suitable hydrodynamic parameters for predicting Tc. The new equation obtained by dimensionless analysis includes flow properties (unit flow discharge, stream power and Reynolds number) and sediment characteristics (MWD) has a good prediction effect on Tc (R2 =0.991, NSE=0.990), and the simulation accuracy is greater than that of other Tc equations deduced in this study. These results promote understanding of the relationship between Tc and sediment characteristics and contribute to further elucidating the erosion process of soilrock mixtures.

Microhabitat partitioning between sympatric intertidal fish species highlights the importance of sediment composition in gravel beach conservation.

Gravel beaches in the Mediterranean ecoregion represent an economically important and unique habitat type. Yet, burgeoning tourism, intensive coastal development and artificial nourishment of beaches may jeopardize their ecological communities. To date, species that reside on gravel beaches and the consequences of beach alterations are poorly understood, which hampers the development of a sustainable coastal tourism industry along the region's shorelines. Using a simple collection method based on dredging buckets through the intertidal section of beaches, we quantified the microhabitat association of two sympatric clingfish species in the genus Gouania at seven natural and an artificial gravel beach based on sediment characteristics. We hypothesized that slender (G. pigra) and stout (G. adriatica) morphotypes would partition interstitial niche space based on sediment size, which may affect the vulnerability of the species to changes in gravel beach composition due to coastal development. We detected substantial differences in gravel composition within and among the sampled beaches which suggests scope for microhabitat partitioning in Gouania. Indeed, we found significant relationships between species identity and the presence/absence and abundance of individuals in hauls based on their positioning on PC1. Our results suggest that modifications of gravel beaches through coastal development, including beach nourishment, intensifying coastal erosion, or artificial beach creation, may have detrimental consequences for the two species if sediment types or sizes are altered. We posit that, given the simplicity and efficacy of our sampling method and the sensitivity of Gouania species to prevailing gravel composition, the genus could serve as an important indicator for gravel beach management in the Mediterranean ecoregion.

Features of the Physical-Mechanical Properties and Chemical Composition of Chert Gravels

The chert gravels are a by-product of sand mining in the south of Israel; the reserves amount to tens of millions of tons and continue to grow. The attempts of their comminution for the production of aggregates by conventional mechanical methods have not yet been successful due to the high abrasiveness, as well as the flaky form of their fracturing. This study was motivated by the need to find an alternative method to rock comminution that would ensure aggregate production in line with the requirements of the asphalt and concrete industry. This article deals with the first inevitable stage on the way to this goal, which consists of an extensive laboratory study of the physical and mechanical properties of the chert gravels, as well as the features of their chemical composition. The results show that the chert rock, consisting of quartz micro grains, contains calcium, sulfur, phosphorus, and barium impurities. The rock is characterized by extremely low porosity and water absorption (less than 1%) and high values of tensile strength (10.8 ± 3.3) and electrical resistivity (23.0 ± 11.9 kΩm). The cubic uniaxial compression strength of the rock is relatively not high (37.3 ± 10.4 MPa), which contradicts the assessment made based on the Schmidt hammer and Point Load studies (158 ± 30.4 MPa and 321 ± 118.5 MPa, respectively).

Application of the XBeach-Gravel Model for the Case of East Adriatic Sea-Wave Conditions

Croatia’s coast located on the eastern Adriatic is rich with small gravel beaches with limited fetch. This leads to a specific low-energetic wave climate compared to most other beaches, while their gravel composition makes them unique. Most management of these beaches is performed without understanding the sediment transport occurring on the beaches. XBeach-Gravel is a numerical model capable of simulating bed-level change on gravel beaches, but lacks validation in the case of low significant wave height (under 2.5 m) and low peak periods (under 6 s), conditions that are present on the eastern Adriatic. Based on measurements performed in both laboratory conditions in a water canal in Hannover and actual storm wave conditions on Ploče beach, calibration of the model is performed. Model results are compared between laboratory conditions and field conditions for comparable wave conditions. XBeach-Gravel can simulate low-energetic events resulting in berm formation and berm buildup with a high Brier skill score if calibrated. Simulation of laboratory conditions requires high transport coefficient values and shows more sediment transport than similar wave conditions in the field. Calibration for field conditions is dependent on geodetic survey data capable of isolating wave events with dominant cross-shore transport, but once calibrated, XBeach-Gravel can achieve good to excellent Brier skill score values in simulating sediment change in low-energetic wave conditions on the eastern Adriatic.

Weathering process of the alluvial fans in western Sichuan basin, eastern margin of the Tibetan Plateau

Correlating morphological surfaces, such as terraces and alluvial fans, is necessary in geomorphology researches. Gravel characteristics have been analysed to estimate the weathering degree. However, the composition of gravels was complicated and a feasible quantitative method is still need. Therefore, the objective of this study was to investigate the weathering process of an alluvial fan in western Sichuan Basin and find a practical method in correlating morphological surfaces. The Qingyi River frequently migrated since 500 ka ago and generated several paleo alluvial fans, one of which is the Dansi alluvial fan. Major and trace element samples form an uninterrupted outcrop of the Dansi fan were tested to estimate the weathering process of a single fluvial profile. Results showed that the weathering index decreased regularly with depth, meaning that the surficial sample could represent the weathering degree of the morphological surface. In addition, the sand fillings between the gravels in the river sediments were sensitive to the weathering process and were able to reflect quantitative weathering degree. Therefore, we suggested that the weathering index of the sediments closed to the surface can represent the weathering degree of morphological surfaces.

Towards physical habitat characterisation in the Antarctic Sør Rondane Mountains using satellite remote sensing

Ice-free areas occupy less than 0.25% of the Antarctic surface, and mainly occur along coastlines, or as inland nunataks protruding from the extensive ice sheet. Their extreme environment and geographical isolation have contributed to the evolution of highly adapted, and largely endemic terrestrial biota. Physical habitat mapping is important to identify the main drivers of spatial variation in soil biodiversity, to predict its response to climate change and to help conservation planning. In this paper we retrieved remotely sensed Land Surface Temperature (LST) and Digital Surface Models (DSM) for the Sør Rondane Mountains in East Antarctica from respectively the Thermal InfraRed Sensor (TIRS) on Landsat 8 and the Pléiades constellation of high resolution optical imagers. Satellite data were combined with ground truth temperature and elevation measurements with the aim to assess the performance of these remotely sensed data. Over a 2 year period, satellite derived LST corresponded to in situ temperature with Mean Average Difference (MAD) of −2.5 K, and Root Mean Squared Difference (RMSD) of 6.3 K. Lower biases were observed for periods when the data loggers were frozen or snow covered (MAD −1.8K) compared to intervals where the devices were not frozen (MAD −4 K), with larger scatter (RMSD 7 K) being observed during the latter. These larger MAD and RMSD are caused by the differential heating of the top of the gravel/rocks as observed by the satellite compared to their underside, where the loggers were installed, and are also impacted by the time step of the in situ logging (3 h) and the non–linear heating of the surface. In addition, for the different study sites different biases were observed as a result of the spatial resolution of the TIRS, depending on the composition, structure, geomorphology, and the surroundings of the logger position. Sites on a narrow rock outcrop (e.g. the Perlebandet and Utsteinen nunataks) show a negative bias due to the surrounding ice fields decreasing the satellite pixel average temperature compared to the in situ measured temperatures. For sites with a more extensive rock and gravel composition further away from the ice sheet (Dry and Yuboku Valleys), a positive bias was found as a result of the temperature differential between the exposed top and covered bottom of the rocks and gravel. The DSM derived from Pléiades (without bias correction) showed in general a bias of −6 m (MAD) and scatter of 9 m (RMSD) when compared to the Reference Elevation Model of Antarctica and IceSAT-1 LIDAR data. Lowest errors were also found here for the extensive Dry and Yuboku Valley sites (respectively −5 and 3 m MAD, 7 and 4 m RMSD). Correspondence with in situ logged GPS positions was slightly worse, with a positive bias of 12 m (MAD) and scatter of 15 m (RMSD) across the sites. An analysis on the basis of these LST and DSM datasets, show a clear separability of sites by their average temperature and solar exposition (in terms of slope and aspect) at the time of Landsat overpass. Due to the Landsat overpass times, the LST datasets are however strongly biased, and further work is needed for a better understanding of the light and temperature climate in the ice-free regions. This could for example be achieved by coupling the DSM to a solar irradiance and terrain shadowing model.

Impact of climate on landscape form, sediment transfer and the sedimentary record

AbstractThe relationship between climate, landscape connectivity and sediment export from mountain ranges is key to understanding the propagation of erosion signals downstream into sedimentary basins. We explore the role of connectivity in modulating the composition of sediment exported from the Frontal Cordillera of the south‐central Argentine Andes by comparing three adjacent and apparently similar semi‐glaciated catchment‐fan systems within the context of an along‐strike precipitation gradient. We first identify that the bedrock exposed in the upper, previously glaciated reaches of the cordillera is under‐represented in the lithological composition of gravels on each of three alluvial fans. There is little evidence for abrasion or preferential weathering of sediment sourced from the upper cordillera, suggesting that the observed bias can only be explained by sediment storage in these glacially widened and flattened valleys of the upper cordillera (as revealed by channel steepness mapping). A detailed analysis of the morphology of sedimentary deposits within the catchments reveals catchment‐wide trends in either main valley incision or aggradation, linked to differences in hillslope–channel connectivity and precipitation. We observe that drier catchments have poor hillslope–channel connectivity and that gravels exported from dry catchments have a lithological composition depleted in clasts sourced from the upper cordillera. Conversely, the catchment with the highest maximum precipitation rate exhibits a high degree of connectivity between its sediment sources and the main river network, leading to the export of a greater proportion of upper cordillera gravel as well as a greater volume of sand.Finally, given a clear spatial correlation between the resistance of bedrock to erosion, mountain range elevation and its covariant, precipitation, we highlight how connectivity in these semi‐glaciated landscapes can be preconditioned by the spatial distribution of bedrock lithology.These findings give insight into the extent to which sedimentary archives record source erosion patterns through time.

ENGINEERING PROPERTIES OF LATERITIC SOIL IN OTUN AREA, EKITI STATE, NIGERIA

Lateritic soils at Otun Ekiti, Ekiti state, southwestern Nigeria were investigated with respect to their geotechnical properties and their suitability for subgrade and sub – base construction materials. Four disturbed lateritic soil samples (sample A, B, C and D) were selected for the various laboratory techniques. The grain size analyses, the specific gravity tests, the atterberg limit tests, compaction, California bearing ratio and shear box tests were carried out on the samples. The grain size analysis shows that sample A is gravelly silt-clayey sand. Sample B is silt – clayey gravel composition. Sample C is gravelly silt-clayey while Sample D is silt-clayey gravel. Atterberg consistency limit test indicate that sample A has 30.0%, liquid limit 19.5% plastic limit, 10.5% plasticity index, 9.1% shrinkage limit. Sample B has liquid limit of 27.0%, 16.2% plastic limit, 10.8% plasticity index and 7.4% shrinkage limit. Sample C has a liquid limit of 32.4%, plastic limit of 15.6%. It has a plastic index of 16.8%, Shrinkage limit of 9.7% while Sample D has a liquid limit of 36.2%, plastic limit of 17.7%. It has a plastic index of 18.5% and 11.1% as shrinkage limit. Thus, the soil is classified to be intermediate plasticity which can be used for sub – grade and sub – base materials. The soil samples are above the activity (A) line in the zone of intermediate plasticity (CL) which suggests that they are inorganic soils. Based on engineering use chart, the workability as construction engineering is good to fair particularly as erosion resistance in canal construction. However, the high shrinkage limit may also reduce erosion in this area because of cohesion of the plastic clay material. The California Bearing Ratio (CBR) values are within 2 – 3% (mean = 2.75%) and 2 - 4% (mean = 2.75%) in sample A and sample B respectively while California Bearing Ratio (CBR) of 2 - 4% (mean = 2.75%) and 2 – 3% (mean = 2.75%) in sample C and sample D respectively. This implies that the materials can be used as a sub-grade to base course material for support of flexible pavements. The compaction tests for the optimum water content for sample A is 15.0% and 13.0% for standard and modified proctor respectively. The standard and modified proctor for sample B is 15.0% and 14.0% respectively. The compaction tests for the optimum water content for sample C and D is 15.0% and 14.0% for standard and modified proctor respectively. The compaction tests for Sample A indicate a higher fine fraction and thus a higher optimum moisture content while sample B, C and D has higher coarse fraction with lower optimum moisture content. The cohesion falls within 70-90Kpa (mean = 79Kpa) and the angle of internal friction ranges from 260 - 320 with mean of 280 for standard and modified compaction energies respectively. The results obtained from geotechnical analysis suggest that the soil is good to fair as erosion resistance in canal construction because of its high bearing capacity and it can also be used as sub – grade and base course in road construction. Keywords: Lateritic soil, Construction, Erosional and Geotechnical.

An extensional collapse model for the Lhasa–Qiangtang orogen in Central Tibet

Large-scale geodynamic processes not only result in magmatism, but also generate corresponding tectonic and sedimentary evidence. Therefore, magmatic, sedimentary, and tectonic evidences can be used to investigate lithospheric geodynamics. This study reports Late Cretaceous magmatic–sedimentary–tectonic evidence from the Tari Co area in central Tibet of post-collisional extensional collapse of the lithosphere. Zircon UPb dating shows that the Tari Co Late Cretaceous igneous rocks formed during ca. 90–75 Ma, including (1) thickened lower crust-derived adakitic granodioritic porphyry (90.4 ± 1.0 Ma and 90.7 ± 1.0 Ma) with high Sr/Y (34.4–53.8) ratios but low Y (5.48–9.14 ppm), Cr (10.2–14.4 ppm), and Ni (4.33–6.63 ppm) contents; (2) delaminated lower crust-derived dioritic porphyry dike (80.5 ± 1.6 Ma) with high Mg# (48–53) and moderate SiO2 (57.9–63.6 wt%), Cr (40.3–54.1 ppm) and Ni (43.5–56.4 ppm) contents; and (3) mafic dikes (74.8 ± 1.0 Ma) derived from different magma sources. According to sedimentary facies, gravel composition, and depositional age, the Upper Cretaceous Jingzhushan Formation in study area is divided into the lower subunit and upper subunit. Different from the typical lower subunit of the Jingzhushan Formation with sub-rounded limestone gravels as the main components, the upper subunit of the Jingzhushan Formation comprises slump breccias and coarse conglomerates. The gravel clasts in the upper subunit are mostly adakitic granodioritic porphyry (90.1 ± 1.4 Ma), indicating a sedimentary response to the crustal uplift associated with lithospheric delamination. In terms of structural deformation, the study area gradually entered the post-collisional setting in the late Late Cretaceous time (ca. 79-75 Ma), forming an east-west trending extensional tectonic system comprising extensional and step faults, grabens and horsts, and mafic dikes. Based on the Late Cretaceous geological records and previous studies, we suggest a three-stage post-collisional model including melting of thickened crust, lithospheric delamination, and gravitationally driven ductile collapse. Our results provide new insights into the evolution of continental orogens.

Unraveling the origin of the Parnaíba Basin: Testing the rift to sag hypothesis using a multi-proxy provenance analysis

Syneclises are long-lived sedimentary basins characterized by complex subsidence and erosion histories. The premise that these geotectonic units evolve from initial rifting processes following thermal (or flexural) subsidence is widespread in the geologic sciences and, to this day, remains a controversial issue. Seeking to test this hypothesis, we proceeded a novel multi-proxy provenance study aiming to identify differences (and/or similarities) in the sedimentary signal and source areas of the Jaibaras (rift) and Parnaíba (sag) basins. We conducted a detailed analysis of trace elements geochemistry of detrital rutile grains, macroscopic gravel composition and paleocurrents from the sedimentary deposits of the Aprazível Formation (Ediacaran - Cambrian, top of Jaibaras Basin) and the Ipu Formation (Ordovician, basal unit of Parnaíba Basin). Our data reveal that important changes in source areas occurred between the end of the rifting and the beginning of the sag phase, reinforcing the hypothesis that the evolution of the Jaibaras and Parnaíba basins were not genetically related. Our results demonstrate that conglomerates of the rift sequence are predominantly composed of volcanic, sedimentary, and metamorphic angular to sub-angular clasts, pointing to diverse, nearby source areas. Contrastingly, conglomerates of the initial sag sequence have greater sedimentary maturity, with dominant rounded vein quartz clasts and other minor source contributions, which suggest distant source areas, showing a consistent paleocurrent direction towards NW. Indeed, the detrital rutile trace elements geochemistry demonstrates that the source areas of these two units were distinct, revealing an important decrease in the input of granulite facies and metamafic grains in the sag basin comparing with the rift succession. In conclusion, as well as paleomagnetic and geochronological studies, the provenance methods using a multi-proxy approach proved to be an effective and powerful technique for distinguishing modifications in the sedimentary signal between rift-to-sag sequences.

Neogene fluvial sediments in the northern Jinshaan Gorge, China: Implications for early development of the Yellow River since 8 Ma and its response to rapid subsidence of the Weihe-Shanxi Graben

Origin of the Neogene fluvial sediments in the Jinshaan Gorge is a significant issue concerned with development of the Yellow River. Field investigation shows that the bedrock topography underneath the Neogene fluvial sediments is an up to 8–10 km-wide valley (The Tanghsien-phase valley). The Tanghsien-phase bedrock valley is made up of two flat terrace surfaces. Altitude evidence shows the Neogene fluvial sediments almost continuously distribute on a successively southward-lowering bedrock valley along the gorge. Sedimentology analysis based on roundness and gravel composition is performed and two types of Neogene gravels are classified. The first type of gravels shows the same provenance as those on the lower Quaternary terraces, namely, they were abandoned by the same river -a south-flowing river through the Jinshaan Gorge area or the ancient Yellow River. The second type of gravels interbedded with the Baode red clay could be alluvium from the Lüliang Mountain. Magnetostratigraphy indicates that the oldest fluvial sediments in the Hequ and Baode areas can be constrained to ca. 8 Ma and the sediments have a westward younger variation trend. The westward younger fluvial sediments during 8–3.7 Ma imply that the ancient Yellow River through the modern Jinshaan Gorge area might have undergone a fairly long-time lateral erosion progress and have shaped the broad valley under the circumstance of stable climate and tectonics. Owing to pulsed subsidence of the Weihe-Shanxi Graben driven by northeastward growth of the Tibetan Plateau since the Pliocene, the lateral planation progress of the Yellow River was broken up and the inset Jinshaan Gorge was finally formed.

Survival under the Gravel: the Effects of Egg Size and Parental Identity on the In Situ Hatching Success of Chinook Salmon

AbstractEarly‐life mortality in salmon is influenced by both extrinsic (i.e., environmental) and intrinsic (i.e., parental) factors; however, the intrinsic factors have rarely been studied in the wild and relatively little is known about how egg mass and parental effects mediate in situ survival. Thus, we addressed four research objectives related to intrinsic factors and the early‐life survival of Chinook Salmon Oncorhynchus tshawytscha: (1) assess the effect of egg mass and parental effects on in situ hatching success, (2) assess the effect of redd gravel composition and its interaction with egg mass on in situ hatching success, (3) determine whether in situ egg mass–survival relationships have population‐level consequences, and (4) determine whether results from hatchery studies translate to the wild. Embryos from three Chinook Salmon populations located in the Laurentian Great Lakes were reared from fertilization to 15 d posthatch, both in the hatchery and in the wild. We found that egg mass influenced in situ hatching success in the Credit (concave down) and Sydenham rivers (positive‐linear), whereas there was no relationship between the two variables in the Pine River. Maternal identity explained a significant amount of the variation in hatching success for the Pine (20%) and Sydenham (12%) rivers. Within populations, no interaction was found between egg mass and gravel composition; however, hatching success was negatively related to the sand content of a redd when the data were pooled among the populations. Importantly, egg mass and quantitative genetic parameter estimates were different between samples from the hatchery and those from the wild, indicating that hatchery‐based observations cannot be transferred to the wild. Finally, we used both the in situ survival data and previously published data in a simulation analysis, which showed that both linear and nonlinear egg mass–survival relationships can greatly influence the number of alevins produced by a population, depending on where the population egg mass distribution falls along an egg mass selection gradient.

Late Pliocene establishment of exorheic drainage in the northeastern Tibetan Plateau as evidenced by the Wuquan Formation in the Lanzhou Basin

The fluvial archives in the upper-reach Yellow River basins provide important information about drainage history of the northeastern Tibetan Plateau (TP) associated with geomorphologic evolution and climate change. However, the Pliocene fluvial strata within this region have not been studied in detail, hence limiting the understanding of the late Cenozoic development of regional fluvial systems. In this paper, we present the results of a study of the geochronology, sedimentology, and provenance of the fluvial sequence of the Wuquan Formation in the Lanzhou Basin in the northeastern TP. Magnetostratigraphic and cosmogenic nuclide burial ages indicate that the Wuquan Formation was deposited during 3.6–2.2Ma. Furthermore, sedimentary facies, gravel composition, paleocurrent data, and detrital zircon UPb age spectra reveal that the fluvial sequence resembles the terraces of the Yellow River in terms of source area, flow direction, and depositional environment. Our results indicate that a paleo-drainage system flowing out of the northeastern TP was established by ca. 3.6Ma and that the upstream parts of the Yellow River must have developed subsequently from this paleo-drainage system. The late Pliocene drainage system fits well with the dramatic uplift of the northeastern TP, an intensified Asian summer monsoon, and global increase in erosion rates, which may reflect interactions between geomorphic evolution, tectonic deformation, and climate change.

Impacts of gravel jetting on the composition of fish spawning substrates: Implications for river restoration and fisheries management

Fine sediments can impact river biota, with egg and larval stages of lithophilic fish particularly sensitive to deposition of sand- to clay-sized particles (‘fines’) in spawning gravels. Mitigation and restoration methods include jetting to cleanse gravels of fines. Despite wide application, impacts of jetting on gravel composition and quality have rarely been quantified. Here, gravel jetting impacts on sediment composition in the River Great Ouse (UK), were tested during an in-situ experiment completed at riffle (55.6±13.4m2) and patch (0.3m2) scales to determine its magnitude and persistence on surface and subsurface substrate conditions. Before-after (riffle) and control-impact (patch) designs were used, with bedload sediment traps installed downstream of experimental patches to investigate the sediments mobilised during jetting. At the riffle scale, surface grain size was significantly altered; fines were removed resulting in coarser and better-sorted sediments. Similar patterns were detected at the patch scale, although sediment sorting was not significantly altered. Despite reduced fine sediment content of subsurface gravels at the riffle scale, the overall grain size composition was not significantly altered. At the patch scale, no subsurface improvements were detected. Temporally, at the riffle scale, no changes in surface or subsurface sediments lasted more than 12 months; patch scale changes generally persisted for less than 3 months. Thus, whilst gravel jetting could improve spawning gravel quality for surface spawning fishes, including European barbel Barbus barbus, its effects are short-lived. Because subsurface sediments are not affected by gravel jetting, the benefits are limited for redd-building fishes, such as salmonids. Consequently, reducing fine sediment delivery to rivers, such as by changes in agricultural practices, is more sustainable for managing excessive river sedimentation.

Influence of gravel segregation on gluing solution solidification in a railway ballast

Influence of gravel segregation on gluing solution distribution in a realistic railway ballasts is investigated numerically. The rheological characteristics of the gluing solution are accounted for by using a coupled elasto-visco-plastic stress model with an asymptotic time increasing viscosity. The realistic railway ballast is accomplished by using the vertex identification technique, in which the regulations of the gravel composition in ballast practice are followed. Specifically, a uniformly distributed one and a segregated one induced by the difference in gravel size and gravel shape are generated. The rheological model of the gluing solution and twofold ballasts are incorporated into the finite element code of ANSYS\(^{\copyright }\) to study the flow characteristics and time-dependent solidification of the gluing solution. Relatively concrete vertical and lateral gravel–gravel adhesion in twofold ballasts can be generated by using denser network arrangement of the gluing solution; the vertical penetration in the uniform ballast is slightly deeper than that in the segregated ballast, while a slightly reverse tendency in the lateral extension near the upper and central parts appears. However, the difference in the solidified gluing solution distributions in both ballasts is essentially insignificant, indicating that the influence of the gravel segregation needs not necessary to be taken into account in gluing practice when percolation is not taken into account.

Provenance and depositional conditions of fluvial conglomerates and sandstones and their controlling processes in a rift setting, mid-Permian lower and upper Quanzijie low order cycles, Bogda Mountains, NW China

This study investigates how provenance lithology, transport distance, and depositional and paleoclimatic conditions had affected the composition and texture of fluvial conglomerates and sandstones in the Middle Permian lower and upper Quanzijie low-order cycles, Bogda Mountains, greater Turpan-Junggar intracontinental rift basin, NW China. Composition and texture of gravels in conglomerates and sandstones define two conglomerate and two sandstone petrofacies, respectively, in Tarlong-Taodonggou area in southern Bogda and Dalongkou area 70km to the north in northern Bogda. Conglomerate Petrofacies I occurs in Tarlong-Taodonggou and is dominated by basaltic gravels, whereas Conglomerate Petrofacies II occurs mainly in Dalongkou and is dominated by sedimentary gravels. Sandstone Petrofacies I occurs in Tarlong-Taodonggou and contains dominantly basaltic lithics, few sedimentary lithics, and minimal quartz. It is compositionally immature and texturally immature to submature. The compositional maturity increases upsection. Conglomerate Petrofacies I and sandstone Petrofacies I both indicate the young Tian Shan arc to the south as the main sediment source and rift shoulders as a local source. Sandstone Petrofacies II occurs in Dalongkou and contains dominantly sedimentary lithics and abundant and well-developed pedogenic clay coats. The petrofacies in Dalongkou indicate older rift sedimentary rocks exposed at rift shoulders as the main sediment source and distant suture zones as a minor source. In summary, the composition and texture of Quanzijie conglomerates and sandstones are mainly controlled by provenance lithology and, secondarily, depositional and paleoclimatic conditions and transport distance. The results substantiate the rift origin of the Turpan-Junggar basin in Middle Permian, which had many half-grabens and grabens and was bordered by a volcanic arc at the southern basin margin.

Soil‐Geomorphology and Micromorphology of a Natufian Depositional Record at El‐Wad Terrace, Mount Carmel, Israel

The Natufian sequence at the site of el‐Wad Terrace (EWT) shows a complex depositional record derived from intertwined soil‐geomorphic and human processes. In order to identify site formation processes at EWT, we analyzed gravel composition, its distribution within the stratigraphic sequence, and micromorphology of both fine‐grained material and gravel rims. The fine deposits within the EWT sequence are magnetically enhanced anthropogenic sediments mixed with a colluvial component. They contain miniscule burnt bones, charcoal, and calcareous aggregates reminiscent of reworked ash. The constructed stone floors in the earlier Early Natufian (ca. 15.0–13.7/13.0 ka) are largely covered by crusts on their undersides. In thin sections, the crusts exhibit a sequence of thin phosphate coatings directly overlying limestone calcite followed by clayey and secondary pedogenic calcite on the outer side. The expected post‐depositional erosion of floors was likely hampered by their cementation resulting from pedogenic calcite redeposition. The major break in coarse deposition appears to have occurred in the later Early Natufian occupation phase marked by low rate of scree formation.

Late Saalian and Weichselian glaciations in the German Baltic Sea documented by Pleistocene successions at the southeastern margin of the Arkona Basin

Seismic profiles and numerous sediment cores of a planned offshore wind farm area northeast of Rügen Island provide a unique insight into the distribution and thickness of glacial deposits in the southern Baltic Sea. Fine gravel analysis enabled recognition of five tills that correspond to different ice advances. On the basis of a 3D structural model, the main Pleistocene events could be reconstructed and correlated with stratigraphical records in the circum‐Baltic area comprising Marine Isotope Stages (MIS) 6 to 2. The oldest till was deposited during the Late Saalian Warthe advance (qs2; c. 150–130 ka). It is only preserved in ENE–WSW trending subglacial channels incised into Upper Cretaceous soft chalk. Isolated rafts and remnants of two Middle Weichselian tills occur locally, whereas Eemian interglacial sediments are missing. The older till (qw*) has an unusual fine gravel composition and might have formed during ice advances known only from northern Denmark and northern Poland (c. 65–60 ka). The younger till represents the Warnow advance (qw0) in NE Germany that can be correlated with the Danish Ristinge advance (c. 55–50 ka). Furthermore, two tills deposited during the Late Weichselian Last Glacial Maximum (c. 24–16 ka) occur. One can be correlated with the Pomeranian advance (qw2), while the other has characteristics typical for the Mecklenburg advance (qw3). These advances eroded older Pleistocene deposits, thus probably also removing the till of the Brandenburg/Frankfurt advance (qw1) – in contrast to the onshore areas. The Pomeranian till is limited to the southeast, close to the shallow Adlergrund, but the Mecklenburg till covers the whole study area. This first detailed lithostratigraphical classification of till units from the Arkona Basin allows for the identification and correlation of Pleistocene successions in other parts of the southern Baltic Sea.