Characteristics of the sediments hosting the Thracian settlement near the town of Letnitsa

The Thracian settlement near the town of Letnitsa is situated on the left fluvial terrace of the Osam River. Hosting sediments are determined as sandy clayey silts, limy in various degrees. Deposits from the western and central parts are compared and both show similar mineralogical composition. These from the central parts contain more fine silt and clayey fraction, which supposes that these parts could have been flooded by the river.

Fasies Sedimentasi dan Elemen Arsitektur Formasi Citalang di Desa Sidamukti, Majalengka, Provinsi Jawa Barat

Daerah Majalengka merupakan satu daerah di Jawa Barat yang sangat menarik untuk dilakukan kajian geologi baik yang berkaitan dengan sedimentologi, tektonik maupun paleontologi. Salah satu objek yang menarik untuk dikaji ulang adalah Formasi Citalang, dimana uraian tentang formasi ini masih banyak terdapat perbedaan tentang satuan batuan penyusunnya, umur dan lingkungan pengendapannya. Disini kajian tentang formasi Citalang ditinjau dari sedimentologinya.Formasi Citalang di daerah penelitian Desa Sidamukti, Kabupaten Majalengka, Provinsi Jawa Barat tersusun atas 6 satuan batuan, yaitu: perselingan batupasir dan konglomerat sisipan tuf, perselingan batupasir dan batulempung, perselingan batupasir dan konglomerat, batupasir sisipan batulanau, perselingan batupasir dan konglomerat dengan sisipan batulanau, serta perselingan batupasir dan batulanau. Dari pengukuran penampang stratigrafi lintasan terpilih didapatkan 10 litofasies yang secara keseluruhan dijumpai dalam masing-masing satuan batuan, berupa: Fine Mud (Fm), Fine Silt Mud (Fsm), Massive Sandstone (Sm), Horizontal Sandstone (Sh), Low Angle Cross Lamination Sandstone (Sl), Ripple Cross Lamination Sandstone (Sr), Trough Cross Bed Sandstone (St), Gravel Matrix Supported Graded Bedding (Gmg), Gravel Clast Supported Graded Bedding (Gcg), Gravel Clast Supported Massive (Gcm). Elemen arsitektural yang terbentuk pada sistem pengendapan Formasi Citalang adalah Gravel Bar and Bedforms (GB), Sandy Bedform (SB), dan Sediment Gravity Flow (SG), yang diinterpretasikan terjadi pada lingkungan pengendapan fluvial berupa sungai teranyam.Katakunci: Formasi Citalang, elemen arsitektur, fluvial, litofasies, sungai teranyam.

Seabed geomorphology of the Prokljan Lake – a Krka River estuary on the eastern Adriatic coast (Dalmatia)

<p>Vast areas of the shallow Adriatic shelf were exposed at the time of the Last Glacial Maximum lowstand. This enabled formation of lakes, river valleys and river floodplains that were submerged during the Holocene transgression. Here we present a study of the karst estuary of the Krka River located in central Dalmatia on the eastern Adriatic coast. The Krka River creates a 23 km long estuary extending north from the Šibenik Channel, over the Prokljan Lake, up to the tufa waterfall Skradinski buk. We used high resolution acoustic methods including sub-bottom profiler (SBP) coupled with multibeam echo sounder (MBES) (MBES bathymetry and MBES backscatter) and side-scan sonar (SSS) to investigate the submerged karst river valley and lake system that existed before the Holocene relative sea level rise. A total of 70 km of SBP profiles and a point cloud of 241 991 638 points in the area of 6.2 km<sup>2</sup> were collected during the surveys. Water depth ranges from 5 m b.s.l. in the most northern part of the study area, to 25 m b.s.l. in the southern part of the Prokljan lake.</p><p>To create a better geomorphological and geological classifications of the seabed, we made a network of 36 ground truthing stations where we sampled sediments with Van Veen grab sampler and obtained underwater images. Sediment samples were analyzed for grain size, bulk density, carbon and nitrogen concentrations, as well as mineralogical XRD analysis and magnetic susceptibility. We combined gathered data with GIS classification tools to create accurate seabed maps of the area. Our results also showed that well-defined submerged river canyon in the Prokljan Lake area was filled with three sedimentary units: fluvial, brackish and marine. Quaternary sediment thickness is up to 15 m. Seabed geomorphology of the investigated area is characterized by many submerged tufa barriers. They are similar to present barriers upstream of the Skradinski buk waterfall. These unique karst geomorphological features, that grow as algae and mosses are encrusted by carbonate, enabled formation of lakes, as well as prevented a marine flooding during the Holocene sea-level rise. The depth of each barrier (4.5 to 12 m b.s.l.), in connection to the onset of marine sedimentation within the estuary, can be used as an indicator of sea level. Barriers are emphasized on the MBES backscatter data as strong reflectors. Grain size of sampled sediments ranges from poorly sorted sand and gravel on underwater barriers to fine silt sediments in the deeper parts of Prokljan Lake. Larger sediment size on barriers is caused by tufa debris while fine silt is sedimented in the deeper parts of the basin. Grain size results vary for different geomorphological provinces, allowing for a more precise (GIS) classification and description of the seabed.</p><p>This work was supported by the Croatian Science Foundation Project “Sediments between source and sink during a late Quaternary eustatic cycle: the Krka River and the Mid Adriatic Deep System” (QMAD) (HRZZ IP-04-2019-8505).</p>

Shallow gas hydrates off southwest Taiwan and their mechanisms

We have collected two shallow gas hydrate samples at two sites having different geological settings off southwest Taiwan during the cruise MD214 in 2018. The first core site, MD18-3542, is on the South Yuan-An East Ridge at ~ 1200 m water deep, where a structural unconformity covered by fine-silt sediments appears at ~ 5.5 m below the seafloor. The second core site, MD18-3543, is close to the Good-Weather Ridge at ~ 1100 m water deep, where a gas-related pockmark structure and authigenic carbonates are present at shallow strata with fine-silt sediments near the seafloor. Sediment properties of core MD18-3542 are distinctively different above and below the layer corresponding to the unconformity. Both cores show obvious gaps or voids in the lower core halves. The core features could be linked to the dissociated methane upward migrating from deep strata. Core site settings with upwelling methane would favor the formation of shallow gas hydrates. At site MD18-3542, the shallow hydrate could be formed due to high concentration methane kept beneath the unconformity covered by fine-silt sediments. At site MD18-3543, the shallow hydrate could be formed due to an extremely high flux of upwelling methane trapped either beneath the authigenic carbonates or fine-silt sediments.

Dust Particle Size and Statistical Parameters

Grain ‘size’ can be specified and measured in several different ways. All methods of grain size determination have blemishes, and the choice of the most appropriate method is governed by the nature of the sample and the use to which the data are placed. Four main methods are currently used for size analysis of sands: (a) sieving; (b) settling tube analysis; (c) electro-optical methods, including Coulter Counter analysis and laser granulometry; and (d) computerized image analysis. The classification of the particle size distribution of Kuwait dust was mapped according to the parameters proposed by Folk And Ward (1957) which were widely used for quantitative comparisons between natural grain size distribution and the lognormal distribution that shows better sorted sediments have lower values of σ1. Maps of the distribution of dust in Kuwait were obtained that included: fine sand (F.S.), Coarse sand (C.S), Medium Sand (M.S), Very Fine Sane (V.F.S), Very Coarse Silt (V.C.Silt), Coarse Silt (C.Silt), Medium Silt (M.Silt), Fine Silt (F.Silt), Very Fine Silt (V.F.Silt), in addition to that, the deposition percentage of Clay, Sand, mud (silt plus clay) and silt were provided.

Undrained shear strength of glacial till soils and its determining factors

This article presents results of the test conducted on the undrained shear strength of till clayey soils of Eastern Lithuania, which are characterized by rigid and very stiff consistency and low plasticity. According to the classification of soils presented in LST EN ISO 14688–2:2018 Geotechnical Investigation and Testing – Identification and Classification of Soil − Part 2: Principles for a Classification, the tested soils are classified as sandy low plasticity clays. The undrained shear strength was tested using the triaxial compression (unconsolidated undrained) method. The test results showed that peculiarities of the particle size distribution had a crucial impact on the undrained strength of these soils, i.e. on the correlation of clay and fine silt fractions with the rest of soil components.

Morphology, Mineralogy, and Chemistry of Ocherous Precipitate Aggregates Downstream of an Abandoned Mine Site

Mineral precipitates forming downstream of abandoned and/or uncontrolled mine sites generally act as scavengers for heavy metals, such as As and Sb, leaking from the sites. This study reports the morphology of ocherous precipitate aggregates downstream of Ayuta, an abandoned antimony mine site in Tochigi Prefecture, Japan, because its morphology differs significantly from those reported previously. The morphology of this aggregate consists of stacked, small terraces enclosed by numerous connected rimstone dams, although on a smaller scale compared to typical terrace landscapes. The rimstone pools contained ocherous spheroids precipitates at the bottom. Additionally, stream water and ocherous aggregates collected from the site were investigated for mineralogy and chemistry. As (0.07–0.17 μg/L) and Sb (0.02 μg/L) levels in the stream water were determined, and the distributions of As and Sb in the mineral phases of the precipitate were estimated using a sequential extraction procedure. The investigations revealed that As was adsorbed by iron-bearing ocherous precipitate aggregates, especially ferrihydrite that formed on the stream bank at concentrations, comparable to those reported by other studies (85 mg/kg). This adsorption contributed to the natural attenuation of As in the stream. Sb in the aggregate consisted of ultra-fine silt and clay-size particles of stibnite ore transported from the surrounding area and/or secondary minerals transported by groundwater and surface water.

Particle Size Imbalance Index from Compositional Analysis to Evaluate Cereal Sustainability for Arid Soils in Eastern Algeria

For homogeneous fertilization and crop management practices, this work hypothesized that texture could influence cereal yield, particularly in dry regions. Particle size analysis could help improve knowledge of the soil-plant relationship to obtain favorable conditions for better yield. The objective of this work is to develop a single granulometric index for durum wheat (Triticum durum) that is well correlated with yield. For this purpose, 350 independent samples of cereal soils from eastern Algeria were taken and the recorded yields were linked to these samples. The cutoff yield, which separates sub-populations with acceptable yield from those with less acceptable yield, was determined from the inflection point of the cumulative variance ratio functions related to yield by the Richards’ equation. The result obtained is 2.0 Mg.ha−1, with a theoretical critical chi-square value of 4.2, close to 4.6, which is the critical value of r2granulo as obtained by the Cate-Nelson procedure. The five-granulometric indices were found to be symmetrical around zero as follows: ±0.83 for clay (IC), ±1.73 for fine silt (IFL), ±0.31 for coarse silt (ICL), ±0.44 for fine sand (IFS), and ±1.30 for coarse sand (ICS). The two fractions that most influence the textural imbalance are fine silt (IFL) and coarse sand (ICS), with a contribution of 41% and 37%, respectively. The critical single imbalance index r g r a n u l o 2 can be used for determining cereal suitability for soils in the arid region of eastern Algeria. The lower the r g r a n u l o 2 is, the better the soil for cereal crops.

Particle size partitioning of metals in humus horizons of two small erosional landforms in the middle Protva basin – a comparative study

Partitioning of metals in soil particles of various size classes has been receiving greater significance due to the necessity to predict the behaviour and pathways of the potentially toxic elements in the environment. In this study the analysis of metals’ distribution in various particle size fractions was performed to characterize and compare geochemical features of the topsoil horizons of two small erosional landforms located in uncontaminated area of the central part of European Russia (the Middle Protva basin, mixed forest zone). The landforms represent two typical lithological types of gullies in the study area. Soil samples were fractionated and the concentrations of Fe, Mn, Ti, Zr, Ni, Co, Cr, Zn, Cu, Pb were determined in five particle size fractions: 1–0.25, 0.25-0.05, 0.05−0.01, 0.01–0.001 and <0.001 mm. The metals’ concentrations and their distribution in various particle sizes were found to be related to gully litho-type. The contribution of the clay to the total amount of metals was the greatest for Mn, Zn, Ni and Co in both systems. The highest mass loading for Ti, Zr and Cr came from the coarse silt, while for Cu and Pb it was made by different particle size fractions: the medium and fine silt or the coarse silt. The highest contribution of Fe also came from different fractions, either from the coarse sand or the clay depending on the system.