Sediments In Area Research Articles

Seismic Stratigraphic Analysis of the North Apsheron Trend

The Caspian Basin”s structural settings are – compared to the Southern Caspian Basin – less complex. Except for the Apsharon trend, which is a prominent overall anticlinal structure with an eastward dip of its axis, the area of investigation comprises a major northwest-southeast trending syncline and thus exhibits very limited structural potential. Structural closures are limited to the Pre-Cretaceous levels only which so far have not been tested by wells in the offshore. The Cretaceous forms anticlinal structures along the Apsharon trend. These structures appear open up-dip to the northwest with a potential culmination in the shallow water area not covered by the seismic data available. Wells on the Apsharon trend reaching the Cretaceous did not encounter a reservoir so far. The better potential is supposed to be related to stratigraphic traps. Overall three plays are defined based on the seismic stratigraphic analysis: Cretaceous reef play: Within the Cretaceous, there are good indications for buildups along a trend close to the Turkmenistan border. The definition of structural closures along the trend or potential up-dip pinch-outs along the trend requires further investigations [reprocessing] and a denser seismic grid to outline. Pontian highstand delta: The Pontian highstand delta identified in the centre of the study area is interpreted from the progradation reflection pattern and can be reasonably well delineated as a progradational body with some slumping of distinct lateral extend. The Pontian Unconformity in the area east of the incised Paleo-Volga river and north of the delta is characterized by high amplitude becoming weaker again to the N. This area can be referred to as the delta plain area on the Pontian shelf with a high probability of reservoir-quality sands. Productive Series Onlap/Pinch-out Play: With rising lake level in the South Caspian Basin the Central Caspian Basin was continuously flooded and the pre-existing relief [incised valleys, synclinal trough] became again an area of sedimentation. The relevant formations show northward onlap pinch-outs, the Pereryva pinch-out as the probably most promising reservoir was mapped in detail. The onlap positions of the higher Productive Series as well may represent further exploration potential, a detailed review of these pinch-outs.

Changes in the spatial distribution of total phosphorus in sediment and water column of a shallow subtropical lake

Julian PJ II, Schafer T, Cohen MJ, Jones P, Osborne TZ. 2023. Changes in the spatial distribution of total phosphorus in sediment and water column of a shallow subtropical lake. Lake Reserv Manage. 39:213–230. In shallow lakes, interactions between bed sediment and the water column strongly influence the availability and transport of nutrients. Lake Okeechobee, in South Florida, is a eutrophic, shallow, polymictic lake that exhibits frequent mixing of the water column and resuspension of unconsolidated sediments. The objective of this study was to evaluate the temporal and spatial patterns of water and sediment characteristics and evaluate the linkage of sediment and water column total phosphorus (TP) concentrations. Spatiotemporal generalized additive models identified key periods during which both surface water total suspended solids (TSS) and TP increased, corresponding to hurricane and tropical storm activity. Our models identified regions with persistently greater water column concentrations than the lake average, indicating potential hot spots in resuspension processes and/or internal loading. Sediment bulk density (BD) and TP were inversely correlated, indicating that light, less dense sediments have greater TP concentrations, potentially contributing to the redistribution of sediments and P. An integrated evaluation of surface water and sediment characteristics using a generalized additive model revealed that sediment TP strongly influences water column TP concentrations, potentially explaining the spatial distribution of surface water TP concentrations. The area of the lake with sediment TP concentration ≤500 mg/kg is increasing while the low bulk density sediments area is decreasing, marking a potential improvement in sediment conditions. If this trend persists, it indicates that the lake is increasingly storing P in sediments that can resist entrainment, with significant implications for assessing the trajectory of lake restoration.

Analysis of the Superposition Effect of Land Subsidence and Sea-Level Rise in the Tianjin Coastal Area and Its Emerging Risks

Tianjin is a coastal city of China. However, the continuous rise of the relative sea-level has brought huge hidden danger to Tianjin’s economic and social development. The land subsidence is the most important factor that influences relative sea-level rise. By analyzing the current situation of subsidence in Tianjin through PS-InSAR, it was found that the subsidence rate of the southern plain of Tianjin is slowing down as a whole. In addition, Wuqing and Jinghai sedimentary areas as well as other several subsidence centers have been formed. By establishing a regular grid of land subsidence and ground water to construct a geo-weighted regression model (GWR), it was found that Wuqing sedimentary area as a whole is positively correlated with TCA. According to the relative sea-level change, it can be predicted that the natural coastline of Tianjin will recede by about 87 km2 in 20 years. Based on the research results above, this paper, by using machine-learning method (XGBoost), has evaluated Tianjin’s urban safety and analyzed high-risk areas and main contributing factors. Potential risks to urban safety brought about by relative sea-level rise have been analyzed, which will improve the resilience of coastal areas to disasters.

Refining fine sediment source identification through integration of spatial modelling, concentration monitoring and source tracing: A case study in the Great Barrier Reef catchments

Excess fine sediment delivery is a major contributor to the declining health of the Great Barrier Reef and identifying the dominant source areas of fine sediment has been critical to prioritising erosion remediation programs. The Bowen River catchment within the Burdekin Basin has been recognised as a major contributor and hence received considerable research investment over the last two decades. This study adopts a novel approach to integrate three independently derived sediment budgets produced from a catchment scale sediment budget model (Dynamic SedNet), targeted tributary water quality monitoring and geochemical sediment source tracing to refine and map the sediment source zones within the Bowen catchment. A four year study of water quality monitoring combined with modelled discharge estimates and geochemical source tracing both identified that the Little Bowen River and Rosella Creek were the largest sources of sediment in the Bowen River catchment. Both data sets contradicted initial synoptic sediment budget model predictions due to inadequate representation of hillslope and gully erosion. Recent improvements in model inputs have resulted in predictions that are consistent with the field data and are of finer resolution within the identified source areas. Priorities for further investigation of erosion processes are also revealed. Examining the benefits and limitations of each method indicates that these are complimentary methods which can effectively be used as multiple lines of evidence. An integrated dataset such as this provides a higher level of certainty in the prediction of fine sediment sources than a single line of evidence dataset or model. The use of high quality, integrated datasets to inform catchment management prioritisation will provide greater confidence for decision makers when investing in catchment management.

Investigating Surface Deformation and Its Intrinsic Mechanism in Shenzhen, China Using Sentinel‐1A SAR Imagery

AbstractTo avoid disasters caused by surface deformation in urban areas, monitoring and analyzing the mechanism of surface deformation in urban areas on a large scale and in long‐term series is mandatory. Based on PS‐InSAR technology and using 157 Sentinel‐1A images, the surface deformation in Shenzhen was monitored from 2015 to 2022, and the obtained deformation rate ranged from −22.8 to +23.2 mm/year. In this paper, analysis is presented by integrating urbanization, climate, and geology data from Shenzhen. The analysis indicates that surface deformation caused by natural factors is typically observed in regions with unique geological characteristics, such as seasonal deformation in sedimentary areas and uplift along reverse fault zones. Human factors chiefly cause subsidence, and the areas with greater subsidence are generally urbanized areas (∼10 mm/year), industrial areas (∼20 mm/year), and reclamation areas (∼15 mm/year). The deformation of the reservoir dam is subject to multiple factors. The differential subsidence of 2–8 mm/year at both ends is due to the engineering geological conditions. In comparison, the weak rotation with a linear velocity of 18 mm/year is due to hydrostatic pressure and its structural characteristics. The research results of this paper systematically explore the phenomena and the intrinsic mechanism of surface deformation in Shenzhen, providing a safety basis for urban development and emergency disaster prevention in Shenzhen.

Oxygen depletion and sediment respiration in ice‐covered arctic lakes

AbstractProcesses regulating the rate of oxygen depletion determine whether hypoxia occurs and the extent to which greenhouse gases accumulate in seasonally ice‐covered lakes. Here, we investigate the oxygen budget of four arctic lakes using high‐frequency data during two winters in three shallow lakes (9–13 m maximal depth) and four winters in 24 m deep main basin of Toolik Lake. Incubation experiments measured sediment metabolism. Volume‐averaged oxygen depletion measured in situ was independent of water temperature and duration of the ice‐covered period. Average rates were between 0.2 and 0.39 g O2 m−2 d−1 in the shallow lakes and between 0.03 and 0.14 g O2 m−2 d−1 in Toolik Lake, with higher rates in smaller lakes with their larger sediment area to volume ratio. Rates decreased to ~ 20%–50% of initial values in late winter in the shallow lakes but less or not at all in Toolik. The lack of a decline in Toolik Lake points to continued oxygen transport to the sediment–water interface where oxygen consumption occurs. In all lakes, lower in situ oxygen depletion than in incubation measurements points toward increasing anoxia in the lower water column depressing loss rates. In Toolik, oxygen loss during early winter was less in years with minimal snow cover. Penetrative convection occurred, which could mix downwards oxygen produced by photosynthesis or excluded during ice formation. Estimates of these terms exceeded photosynthesis measured in sediment incubations. Modeling under ice‐oxygen dynamics requires consideration of optical properties and biological and transport processes that modify oxygen concentrations and distributions.

Experimental and numerical modeling of pile-rock breakwater gap arrangement for optimal coastal erosion protection in deltaic coasts

Pile-Rock breakwaters (PRBW) have been constructed as long continuous features in the West Sea of the Mekong Delta. Optimising the gap arrangement and spatial orientation of these continuous breakwaters can result in positive impacts on the velocity field, sediment distribution, and shoreline morphology. In this study, experimental and numerical modelling was performed to investigate the effect of breakwater gaps on bedload sediment transport and nearshore bed morphology. The gap width across various hydrodynamic conditions was found to have a significant impact on bedload sediment transport and nearshore bed morphology. This study found breakwater gaps can result in high current speed and flow due to wave diffraction, which subsequently also accelerates the shoreline and bed erosion process. The gaps also have a positive impact by facilitating sediment supply behind the breakwaters, which enhances the living shoreline. The sediment exchange rate was higher in low water conditions for the emerged breakwater caused by wave circulation stirring up the sediment with higher wave amplitude. During high-water conditions, the results showed a relatively smaller area of sedimentation behind the breakwater. Under high water level conditions, the ability to stir up sediment decreases, resulting in low sediment transport. The findings from this study can be used to optimize the design of pile-rock breakwaters and their performance on the deltaic coast.

Determination of microplastic contamination levels and trends in vast oceanic sediment areas with uncertainty

Small plastic particles, designated as microplastics, are known vehicles of several contaminants desorbed from their surface after being ingested by marine organisms. The monitoring of the levels and trends of microplastics in oceanic areas is essential to identify relevant threats and respective sources whose management should be improved to protect the environmental resources. However, the assessment of contamination trends in large oceanic areas is affected by contamination heterogeneity, sampling representativeness, and the uncertainty of collected sample analyses. Only contamination variations not justifiable by system heterogeneity and their characterisation uncertainty are meaningful and should be taken seriously by the authorities. This work describes a novel methodology for the objective identification of meaningful variation of microplastic contamination in vast oceanic areas by the Monte Carlo simulation of all uncertainty components. This tool was successfully applied to the monitoring of the levels and trends of microplastic contamination in sediments from a 700 km2 oceanic area from 3 km to 20 km offshore Sesimbra and Sines (Portugal). This work allowed concluding that contamination has not varied between 2018 and 2019 (difference of mean total microplastic contamination between −40 kg−1 and 34 kg−1) but that microparticles made of PET are the major type of studied microplastics (in 2019, mean contamination is between 36 kg−1 and 85 kg−1). All assessments were performed for a 99 % confidence level.

Multidecadal heavy metals and microplastic deposition records in an urban lake: the ecological risk assessments and influencing factors.

With the development of urbanization and economic growth, the urban lake ecosystem faces many challenges derived from external factors. As pollutants in the aquatic environment, heavy metals and microplastics negatively influence the urban lake ecosystem due to their intrinsic properties. To understand the distribution patterns and multidecadal deposition characteristics of heavy metals and microplastics, six sediment cores were collected in March 2021 from a Chinese urban lake, Xinghu Lake, and the isotopic composition of cesium-137 and lead-210 was analyzed for the chronology of the sediment core. Here, the classifications of comprehensive ecological risk evaluation methods for heavy metals and microplastics were adjusted further. Meanwhile, the correlations among heavy metals, microplastics, sediment grains, and natural and social factors were further analyzed. The results showed that the sediments of Xinghu Lake were mainly fine silt (39%), and the average surface area of sediment was 1.82 ± 0.60 m2/g. The average concentrations of cadmium, chromium, copper, nickel, lead, vanadium, and zinc were 0.268 ± 0.077, 59.91 ± 16.98, 23.29 ± 6.48, 52.16 ± 13.11, 36.83 ± 11.78, 119.57 ± 26.91, and 88.44 ± 29.68mg/kg, respectively. The average comprehensive potential ecological risk indexes of heavy metals and microplastics in sediment cores were 46.59 ± 9.98 and 105.78 ± 23.32 in Xinghu Lake, and their risks were projected to reach high and very high levels by 2030 and 2050. The annual average temperature was the key natural factor for the abundances of heavy metals and microplastics, and the small sediment grain had a significant correlation with these. Agricultural activities were major pollution sources of heavy metals and microplastics, while the chemical fibers and plastic products were closely related to the abundance of microplastics.

Geological Characteristics and Paleoenvironmental Evolution of Fine-Grained Sediments in the Third Member of the Xujiahe Formation in the Western Sichuan Depression, SW China

This study investigated, in detail, the characteristics of the Late Triassic fine-grained sediments in the third member of the Xujiahe Formation (Xu-3 Member), in the Western Sichuan Depression, and the paleoenvironmental evolution during their deposition through petrological interpretation, mineralogical composition characterization, and element geochemical analysis. According to the mineralogical composition, the Xu-3 Member can be divided into two petrological types, namely clayey fine-grained felsic sedimentary rocks and lime fine-grained felsic sedimentary rocks. The main mineral components are siliceous, clay, and carbonate minerals. Through the cluster analysis of major elements, all samples could be divided into two types with different major elemental characteristics. Trace elements exhibited distinct Sr depletion, relative enrichment of large ion lithophile elements, and high field strength elements. Two REE enrichment patterns were observed, which could be attributed to differences in the provenance area and tectonic background. The paleoclimate of the sedimentary area was warm and humid, but it was hotter and drier in the southern and central parts of the depression. The change trend of paleo-productivity was consistent with the paleoclimate. The waters in the sedimentary environment were mainly brackish water to saline water, with fresh water in the southern part of the depression. The paleo-redox conditions of the waters were mainly sub-oxidation to sub-reduction, but the southern part of the depression was more oxidative. The provenance area experienced a moderate degree of chemical weathering under a warm and humid paleoclimate, same as the depositional area. However, the depositional environments differed between the northern and south-central parts of the depression.

Characterizing groundwater quality for a safe supply of water using WQI and GIS in Bahir Dar city, northwest Ethiopia

Abstract Although both urban and rural residents benefit from drinking enough high-quality water in the right amounts, the degree of contamination from artificial sources has been increasing. The study aims to assess the quality and availability of groundwater potential in Bahir Dar City using geographic information systems (GIS)-based ordinary kriging (OK) and analytical hierarchy process methods, respectively. The concentrations of pH, alkalinity, Escherichia coli, nitrite manganese, and iron in the groundwater of built-up areas were found to exceed the limits set by the World Health Organization. The groundwater quality distribution contained 69.6% of good water, 19.6% of the excellent class, and 10.8% of the poor class. The high potential of groundwater, particularly in the Lake Tana shoreline sedimentation areas, revealed the poor quality class. The results suggest that improving groundwater quality should be prioritized in areas with high potential groundwater availability.

Effect of submerged marine debris on the species compositions and community characteristics of the macrobenthos in the subtidal zone of Jeju Island, Korea

Submerged marine debris alters local species compositions and the characteristics of benthic communities. However, few studies have explored species composition and characteristics within benthic communities. Here, we investigate the effects of submerged marine debris on the species compositions of the macrobenthos, as well as the characteristics of debris distribution, in subtidal sediments and rocky areas. Our results indicated that, when debris is present in subtidal sediment areas, mobile species (arthropods), which do not typically occur in the subtidal sediment area, are highly abundant dominant. In debris-covered rocky subtidal areas, the number of species, density, diversity, and biomass are all low. The Iwagaki oyster (Magallana nippona; megabenthos; > 1 cm) only occurred at debris-free sites. Our study provides evidence that submerged marine debris affects macrobenthos; however, due to the small number of surveys and short distances between sites, some of these effects remain unclear. As such, we will supplement these data in a future study.

Drainage area estimates for synorogenic clastic wedges in the Central Appalachian Basin (sink) with implications for terrane accretion in the hinterland (source)

AbstractSource‐to‐sink studies typically utilize the sedimentary record preserved in basins to infer source area parameters such as estimates of drainage area and discharges of fluvial systems in the hinterland, the characterization of which remains elusive as few geomorphic elements of the hinterland are preserved. Clastic wedges within foreland basin settings often contain fluvial deposits, and the scale of fluvial architectural elements can be used to estimate drainage area and discharge within the accreted hinterland. This study uses thicknesses of fluvial architectural elements within the Late Ordovician Taconic, the Late Devonian‐Early Mississippian Acadian, and the Late Mississippian to Early and Middle Pennsylvanian Alleghanian clastic wedges, together with climatic conditions interpreted from palaeosol data, to estimate the drainage areas and discharges of the river systems which drained the hinterlands of the accreted Taconic and Acadian terrains and the Alleghanian suture of Laurentia and Gondwana. Published detrital zircon age spectra provide insight into ages of source areas of sediments as well as the timing of terrane accretion. The increase in hinterland drainage areas calculated for Late Devonian Acadian Orogeny river systems compared to Late Ordovician Taconic Orogeny river systems can be attributed to the increase in size of accreted terranes to the east of the foreland basins during that period of time. The decrease in hinterland drainage area from the Late Devonian Acadian Orogeny to the Middle to Late Pennsylvanian Alleghanian Orogeny is attributed to the westward migration of the drainage divide as the Alleghanian orogeny proceeded. It is inferred that the drainage divide migrated towards the drier leeward side of the mountain range and caused drainage basins to shrink and split into smaller drainage basins.

The Ries impact and its distal effects in sediments of Central Europe—A review

AbstractThe Ries impact is the most important cosmic event in the younger geological history of Europe. Its effects reach far beyond the area considered so far and are documented in manifold evidence. In this paper, the widely scattered reports in the literature are compiled and supported with investigations by the authors. Besides well‐known ejecta features like the Brockhorizont, Reuter's blocks, and moldavites, little known or forgotten indications, like a lechatelierite and β‐cristobalite occurrence in Bavaria and unusual sedimentation phenomena in northern Germany, are presented. The paleogeographic reconstruction shows that the Ries impact occurred on the southern side of the Neogene Central European mainland. Large parts of this erosional area were devastated by the impact. Pressure waves and thermal radiation had a lasting effect on the landscape within hundreds of kilometers around the impact site. Destruction of the vegetation cover by impact‐induced storms, wildfires, and heavy rainfall generated intense erosion. The adjacent sedimentation area to the north (Paleo‐North Sea) experienced an increased and short‐term supply of terrestrial debris to the marine environment. The stratigraphic coincidence of these exceptional sediments with the Ries event leads us to conclude that the distal effects of the impact are present here, which have so far received little or no attention in this context. The paper considers the different indications and sets them in a large‐scale context.

Study on Optimization of Nozzle Angle for Oxygen-Rich Side-Blown Lead Melting Furnace

Taking an oxygen-rich side-blown lead melting furnace made by a company as the research object, the three-dimensional design software Solidworks was used to construct a model at an equal scale, and established a physical model which is in line with the actual system. Based on the determination of the physical properties of the slag phase and metal phase in the furnace, the VOF multiphase flow model and standard turbulence model in FLUENT were used to simulate the gas–liquid multiphase flow. By adjusting the different inclination angles of the spray gun, we analyzed the distribution changes of key indicators, such as the flow field, average turbulent kinetic energy and gas content in the furnace. At the same time, it was found that the turbulent kinetic energy in the middle of the furnace was large, which could strengthen the winding effect of the material and the best arrangement. The gas content of the upper part of the oxygen gun was high, and the gas content in the middle of the furnace was higher than that in the wall area on both sides and showed a gradual downward trend. If the inclination angle of the spray gun is too small, the agitation of the lower melting area is not strong enough, On the contrary, if the inclination angle is too large, the local flow rate of the sedimentation area increases and the gas content is low. The optimal tilt angle of the spray gun is between 10° and 15°.

GEOCHEMISTRY AND FORMATION CONDITIONS OF GROUNDWATER COMPOSITION IN THE AREA OF MESOZOIC SEDIMENTARY COVER IN TATARSTAN

Mesozoic sediments cover an area of 2870 km2. Mesozoic sedimentary rocks are located in the southwestern part of the Republic of Tatarstan. A thick sequence (up to 390 m) are composed of clay with thin (up to 1 m) layers of sandstone and marl. Permian polygenic sulfate-carbonate-terrigenous deposits underlie the Mesozoic massif. They are exposed in the north of the Mesozoic sediment area.The studied area (~5000 km2) is used for farming. There are no large settlements or industrial enterprises there. The paper considers the specific features of Mesozoic and Permian groundwater composition. There is a trend to improving the groundwater quality with time. The reason of this positive trend is a decreasing technogenic impact and depopulation of the territory. The lateral and vertical hydrogeochemical stratification is identified and characterized. Clay predominating in the massif appears to be the reason for the decreasing intensity of water exchange. Hydrolysis, cation exchange and leaching of carbonate and sulfate minerals add to this trend.The groundwater composition varies widely due to these processes and control specific mineralogical and geochemical features of Mesozoic massif (the saturation of organic substance, the presence of opoques, the primary marine ionic-salt compositions in local areas). Groundwater is more mineralized, with a large amount of organic substance, silicic acid, iron, boron and other micro-components in the area of Mesozoic sediment. The groundwater mineralization increases non-linearly to 6.1 g/l (mainly due to sulfates, chlorides and sodium), and the hardness increases to 50.6 mmol/l in the geological section of this area (up to a depth of occurrence 300 m) in areas with downward filtration. The water hardness decreasess to 1.5–3.9 mmol/l at depths of 100–150 m (up to 200 m) in large areas. Vertical zonality (up to a depth of 150 m) is determined mainly by the leaching processes of carbonate and sulfate rocks outside the Mesozoic development area. Mineralization increases almost according to the linear law to 3.5 g/l (mainly due to sulfates, calcium and magnesium), and hardness – up to 37.7 mmol/ l here.The balneological properties of water are determined by the increased contents of organic substances, silicic acid, iron, hydrogen sulfide, as well as waters of the group “without specific components and properties”.

Investigation of the reduction of sediment deposition and river flow resistance around dimpled surface piers.

To reduce sediment accumulation in urban rivers due to the influence of cylindrical bridge piers on river flow resistance, the hydraulic performances of cylindrical piers were investigated using the computational fluid dynamics software FLOW 3D and compared with experimental data. The method included scouring and sedimentation analysis of piers and showed high accuracy at predicting experimental data. A dimpled surface pier was used as the model, and a series of simulations were conducted to evaluate its hydraulic performance. The results showed that scouring extents of a dimpled surface pier are larger than those of a cylindrical pier under different working conditions. This difference helped reducing sludge sedimentation at the bottom of the river in the former. The ratio of the maximum sedimentation height to the pier diameter ([Formula: see text]), ratio of the sedimentation area, and cross-sectional area of the dimpled surface pier ([Formula: see text]) are all smaller than those of a cylindrical pier at different flow velocities, indicating that dimpled surface piers have a lower silting probability. Compared with cylindrical piers, dimpled surface piers offer less interference to turbulent flow and generate a small-scale spiral flow; a lower lateral velocity is also obtained behind the dimpled surface pier, which leads to lower flow resistances and lower energy dissipation, which helps scour.

Paleogeografické rozšírenie gaderského a ráztockého vápenca (vrchný pelsón – ilýr, hronikum, Západné Karpaty): rešerš

49 localities situated in preserved parts of the tectonic unit Hronicum were examined. The obtained data on the occurrence of brachiopods, bivalve molluscs, cephalopods, conodonts, holoturias and foraminifers in the sediments of the Upper Pelsonian – Illyrian (Jasenie, Schreyeralm, Gader, Ráztoka and unnamed crinoidal limestone) were projected into the paleogeographic scheme of the Hronicum. In the period after the disintegration of the Gutenstein platform, the Hronicum area was divided into a number of differentially synsedimentary subsiding parts. The submerged parts were the sedimentation space of the mentioned types of limestones. Non-submerged parts – carbonate platforms were a source of organodetritus for subsiding areas and a sedimentation area for the Gader Limestone.

Salair–Gornaya Shoria Junction (Northwestern Central Asian Orogenic Belt): Deep Structure and Tectonics from Magnetotelluric Data

Abstract —The Salair fold-thrust orogenic belt (Salair orogen, Salair) is located in the northwestern Altai–Sayan fold area within the Central Asian Orogenic Belt. The Salair orogen is an allochthon overriding the Kuznetsk Basin on a system of imbricate thrusts. The southern flank of the Salair thrust system is tectonically juxtaposed against the Gornaya Shoria terrane which differs markedly from Salair in its geological setting. The Salair and Gornaya Shoria terranes are separated by the Nenya-Chumysh Basin, a deep Mesozoic trough. The Salair orogen is composed of Cambrian–Early Ordovician island arc volcanic and sedimentary rocks, widespread garnet amphibolites and gneisses of the Angurep complex in its southern flank, and the Shalap subduction-related melange in the Alambai ophiolite suture. The southern Salair orogen and its junction with Gornaya Shoria have been imaged down to the lower crust by magnetotelluric (MT) soundings, which is an efficient tool for investigating the deep structure and tectonic history of orogenic areas. The MT surveys were performed at 25 stations on a 120 km long profile. MT data revealed an up to 70 km wide low-resistivity zone (a conductor) traceable till a depth of 20 km between the Salair and Gornaya Shoria terranes. The low-resistivity zone has a complex structure with its outer and interior boundaries dipping almost vertically. The conductor lies under several major geological structures: the Shalap melange, the Nenya-Chumysh Basin, and the NE trending Altai–Salair right-lateral strike-slip fault. The Altai–Salair fault, along which the Salair allochthon was displaced relative to Gorny Altai and Gornaya Shoria, joins the Salair system of imbricate thrusts. The Nenya-Chumysh Basin at the Salair–Gornaya Shoria junction is a deep trough having an asymmetric transversal profile with a steep western side and a shallower-dipping stepped eastern side. The southeastern flank of the basin is a wide area of thin sediments over the Paleozoic basement dipping gently in the northwestern direction. The revealed deep structure of the Nenya-Chumysh trough is consistent with its tectonic model implying an Early Cretaceous basin superposed over an early Jurassic pull-apart basin. Early Mesozoic motions on major faults is a regional-scale phenomenon known from many areas of southern West Siberia.

The Mapping of Road Pavement Structure around the Seismically Active Regions by Using Ground Penetrating Radar

The Banda Aceh-Sigli Road has become the central infrastructure in connecting the capital city of Aceh province with other districts. In some places, the road construction was in rice fields dominated by high sedimentation areas. The Aceh also has the Great Sumatran Fault, which has caused many earthquakes and damaged public infrastructure, including roads. The density of the soil structure as an infrastructure buffer needs to be observed before road damage can endanger the community. This study aimed to apply Ground Penetrating Radar (GPR) as a non-destructive method that detects subsurface conditions based on permittivity parameters. The method is measured using the IDS Georadar Opera Duo instrument, which operates with a frequency of 250 MHz and 750 MHz for a penetration depth of 4 m, which is measured on eight intersecting tracks, where two profiles have a length of 110 m measured in the direction of the road segment and five tracks with a length of 11 m is measured by a cross. GresWin2 software is used for optimal analysis and modeling of 2D radargram. The radargram model describes a subsurface structure consisting of three layers, where the first layer with a depth of 0 – 0.25 m is asphalt, and the second and d layer with a depth of 0.25 – 0.75 m was identified as the base course layer. In comparison, the third layer is interpreted as a sub base course layer at a depth of 0.75 - 4 m below. The analysis results also show a linearly damaged road structure with high propagation speed and large wave amplitude. Therefore, based on data processing, it can be concluded that the application of GPR is a non-destructive, fast, and economical method for evaluating road structures.