Spatial and temporal changes of sediment grain size along Israel’s Mediterranean cliff-dominated beaches

2020 ◽  
Author(s):  
Onn Crouvi ◽  
Ran Shemesh ◽  
Oded Katz ◽  
Amit Mushkin ◽  
Navot Morag ◽  
...  
Keyword(s):  
Grain Size ◽  
Temporal Variation ◽  
High Energy ◽  
Coarse Sand ◽  
Coarse Fraction ◽  
Sand Fraction ◽  
Sediment Grain Size ◽  
Cliff Erosion ◽  
Beach Sediments ◽  
Sand Abrasion

<p>Beach morphodynamics are largely controlled by the interaction of wave climate with beach sediments. Local changes in sediment grain size, shape or density can lead to distinct morphological changes of beach systems subjected to similar energetic inputs. Whereas the spatial variation of grain size along beach profiles has been well studied, the temporal variation in beach grain size has received less attention. Moreover, the fate of cliff-eroded sediments along sandy coasts, with limited tidal effect, was rarely studied as most studies focused on shingle beaches (rocky/pebble rich) especially in coastal environments where tide plays an important role.</p><p>Here we use grain size data to explore the temporal dynamics of beach sediments in cliff-dominated beaches along Israel’s Mediterranean coast and their relationship to cliff erosion as well as sand abrasion/attrition. Our approach is based on repetitive seasonal-scale sampling of surficial sediments along cross shore transects over 3 years. We found that most samples exhibit unimodal particle size distribution (PSD), with a mode either at the fine sand fraction (180-220 µm) composed of quartz, or at the coarse sand to very coarse sand fraction (900-1,200 µm), composed of eolianite rock chips. The coarse fraction dominants the PSD mostly during winter times, whereas at summer times it is usually absent. In addition, this coarse fraction decreases with time that passed since waves reached the cliff base during sea storms. Our results suggest that: 1) The addition of the coarse fraction during winter is related to high-energy wave storms that mobilize and transport cliff-derived materials (taluses) along the beach, and 2) The disappearance of the coarse fraction towards summer is related to sand abrasion by wave and/or by wind action, i.e. breakage of the ~1 mm eolianite rock chips into ~200 µm quartz grains. Our findings emphasize the importance of cliff erosion and sand abrasion in controlling the temporal variation in PSD along cliff-dominated beaches.</p>

scholarly journals Understanding and predicting the temporal variability of sediment grain size characteristics on high-energy beaches

2016 ◽  
Vol 376 ◽  
pp. 109-117 ◽  
Author(s):  
Sam Prodger ◽  
Paul Russell ◽  
Mark Davidson ◽  
Jon Miles ◽  
Tim Scott
Keyword(s):  
Grain Size ◽  
Temporal Variability ◽  
High Energy ◽  
Sediment Grain Size

Analysis of Variance about the Sadiment Size in Jiuyuangou and Tuwei River Watershed’s Silt Dam

2014 ◽  
Vol 1010-1012 ◽  
pp. 1140-1144
Author(s):  
Li Li ◽  
Wei Ying Sun ◽  
Qi He ◽  
Xin Xin Hou
Keyword(s):  
Grain Size ◽  
Analysis Of Variance ◽  
Coarse Sand ◽  
Sediment Grain Size ◽  
Separation Effect ◽  
River Watershed ◽  
Drilling Hole ◽  
Reduction Effect ◽  
Sand Size

Analysising twenty-one silt dams in Jiuyuangou watershed and thirty-six silt dams in Tuwei River Watershed drilling hole sampling’s data, Jiuyuan gou Watershed’s silt dams in coarse sand size mainly concentrated in the 0.05mm,Tuwei River Watershed’s silt dams in coarse sand size mainly concentrated in the 0.05mm~0.10mm,The dam upstream sand size is generally larger than the dam downstream, sorting depends on sediment dam on the dam upstream tosand size, dam upstream sediment grain size is coarse separation effect is better, warping dam and reduction effect is more obvious.

scholarly journals SEAFLOOR SEDIMENT CHARACTERISTICS AND HEAVY MINERAL OCCURENCES AT BETUMPAK CAPE AND ADJACENT AREA, BANGKA STRAIT, BANGKA BELITUNG PROVINCE

2016 ◽  
Vol 27 (1) ◽  
pp. 7 ◽  
Author(s):  
Rohendi Rohendi ◽  
Noor C.D. Aryanto
Keyword(s):  
Grain Size ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Coarse Sand ◽  
Heavy Mineral ◽  
Silty Sand ◽  
Adjacent Area ◽  
Sediment Grain Size ◽  
Gravity Corer ◽  
Scanning Electron

Thirty seafloor of sediment samples have been taken by using gravity corer and grab sampler at Betumpak Cape, and adjacent area of Bangka Belitung. The result of grain size analyses show that there are four sediment units: gravelly sand, gravelly muddy sand, silt and silty sand. Identification of Scanning Electron Microscope (SEM) image on several samples shows the presence of clay mineral such as smectite, alunite, chlorite etc., may resulted from plagioclase weathering of granite. Based on heavy mineral analyses, its highest content is found at MTK-27 (northwest of Betumpak Cape). High content of apatite (0.94% wt and 1.07% wt) is found on coarse sand fractions (115-170 mesh) at MTK-29 (northeast Ular Cape) and MTK-30 (north of Ular Cape). Generally, the heavy mineral accumulation is occurred on medium sand fraction (60-80 mesh) as magnetite (7.86% wt), ilmenite (4.9% wt) and zircon (1.32% wt). Based on these data, it shows that heavy mineral is accumulated on medium to coarse sand. Keywords: sea floor sediment, grain size analysis, heavy minerals, and Betumpak Cape, Bangka strait. Sebanyak 30 sampel sedimen dasar laut telah diambil dengan menggunakan pemercontoh jatuh bebas dan comot di Perairan Tanjung Betumpak dan sekitarnya, Bangka Belitung. Hasil analisis besar butir menunjukkan adanya 4 satuan sedimen, yaitu pasir kerikilan, pasir lumpuran sedikit kerikilan, lanau dan pasir lanauan. Hasil identifikasi citra Scanning Electron Microscope (SEM) terhadap beberapa sampel, memperlihatkan kehadiran mineral lempung seperti smektit, alunit, klorit dll., kemungkinan sebagai hasil pelapukan plagioklas dari granit. Berdasarkan analisis mineral berat kandungan tertinggi terdapat di lokasi MTK-27 (baratlaut Tanjung Betumpak). Akumulasi mineral berat umumnya terdapat pada fraksi pasir ukuran sedang (60-80 mesh) berupa magnetit, ilmenit dan zirkon masing-masing dengan kandungan 7,86 % berat. 4,9% berat dan 1,32% berat. Pada fraksi pasir kasar (115-170 mesh) dijumpai kandungan apatit tertinggi di MTK-29 (timurlaut Tanjung Ular) dan MTK-30 (utara Tg. Ular) sebesar 0,94% berat dan 1,07% berat. Dari data tersebut terlihat, bahwa secara umum mineral berat terakumulasi pada pasir sedang hingga pasir kasar. Kata kunci: Sedimen permukaan dasar laut, analisis besar butir, mineral berat, dan Tanjung Betumpak, Selat Bangka.

scholarly journals Life-cycle analysis of coesite-bearing garnet

2021 ◽  
pp. 1-20
Author(s):  
Jan Schönig ◽  
Hilmar von Eynatten ◽  
Guido Meinhold ◽  
N. Keno Lünsdorf
Keyword(s):  
Grain Size ◽  
Fine Fraction ◽  
Fine Sand ◽  
Inclusion Size ◽  
Coarse Sand ◽  
Coarse Fraction ◽  
Surface Erosion ◽  
Fluid Infiltration ◽  
Size Heterogeneity ◽  
High Degree

Abstract Detrital coesite-bearing garnet is the final product of a complex geological cycle including coesite entrapment at ultra-high-pressure conditions, exhumation to Earth’s surface, erosion and sedimentary transport. In contrast to the usual enrichment of high-grade metamorphic garnet in medium- to coarse-sand fractions, coesite-bearing grains are often enriched in the very-fine-sand fraction. To understand this imbalance, we analyse the role of source-rock lithology, inclusion size, inclusion frequency and fluid infiltration on the grain-size heterogeneity of coesite-bearing garnet based on a dataset of 2100 inclusion-bearing grains, of which 93 contain coesite, from the Saxonian Erzgebirge, Germany. By combining inclusion assemblages and garnet chemistry, we show that (1) mafic garnet contains a low number of coesite inclusions per grain and is enriched in the coarse fraction, and (2) felsic garnet contains variable amounts of coesite inclusions per grain, whereby coesite-poor grains are enriched in the coarse fraction and coesite-rich grains extensively disintegrated into smaller fragments resulting in an enrichment in the fine fraction. Raman images reveal that: small coesite inclusions of dimension < 9 µm are primarily monomineralic, whereas larger inclusions partially transformed to quartz; and garnet fracturing, fluid infiltration and the coesite-to-quartz transformation is a late process during exhumation taking place at c. 330°C. A model for the disintegration of coesite-bearing garnet enables the heterogeneous grain-size distribution to be explained by inclusion frequency. High abundances of coesite inclusions cause a high degree of fracturing and fracture connections to smaller inclusions, allowing fluid infiltration and the transformation to quartz, which in turn further promotes garnet disintegration.

Linking sediment properties with conductivity values: an approach to investigate intra point bar grain-size variability in fluvial deposits

2021 ◽  
Author(s):  
Elena Bellizia ◽  
Jacopo Boaga ◽  
Davide Tognin ◽  
Alvise Finotello ◽  
Marta Cosma ◽  
...  
Keyword(s):  
Grain Size ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Textural Properties ◽  
Coarse Sand ◽  
Statistical Analyses ◽  
Aquifer Management ◽  
Sediment Grain Size ◽  
Point Bar ◽  
Point Bars

&lt;p&gt;Fluvial and fluvio-tidal meandering channels are widespread in coastal areas, where they shape the present-day landscapes and build up thick sedimentary successions. Deposits accumulated by these channels host the most surficial aquifers, which are deeply exploited by agricultural and industrial activities. Understanding sedimentary facies distribution within these deposits is crucial to predict groundwater flow and also has relevant implications for aquifer management.&lt;br&gt;This study focuses on deposits accumulated by a late Holocene meandering river of the Venetian Plain (Northeast Italy). Combining remote sensing and geophysical data, sedimentary cores, and statistical analyses, we characterize the geometry and sedimentology of two adjacent point-bar bodies, with a specific focus on along-bar sediment grain-size distribution.&amp;#160;&lt;br&gt;The study paleochannel is ca. 30 m wide and its planform evolution was reconstructed by analyzing the scroll-bar pattern of the related point bars from satellite images. This channel generated two meander bends, namely B1 and B2, that progressively expanded during their evolution; moreover, bend B1 was affected by a downstream rotation of the bend apex during its final stage of growth.&amp;#160;&lt;br&gt;Geophysical investigations (Frequency Domain Electro-Magnetometer) provided information about the electric conductivity of the studied sedimentary bodies by allowing for the visualization of horizontal 2D maps with averaged conductivity values with a vertical resolution of 1 m. Point-bar bodies are characterized by slightly lower conductivity values (7 to 80 mS/m) than channel-fill deposits (49-147 mS/m), whereas overbank deposits exhibit the highest values (115 to 300 mS/m). In the B1 point-bar, conductivity values reflect the scroll-bar pattern and are lower in the upstream and pool zones, whereas, in the B2 point-bar, the conductivity exhibits almost uniform horizontal values at each depth.&lt;br&gt;Sedimentary cores reveal that the two point bars consist of well-sorted sands, ranging from fine to very coarse sand, with no heterolithic deposits. Bar deposits cover a basal lag consisting of very coarse sand with shell fragments. Channel-fill deposits are made of fine to very fine sand with muddy intercalations. Overbank deposits consist of massive mud, which is locally organic-rich.&lt;br&gt;The combination of core analysis and conductivity maps highlights a correlation between conductivity values and sediment textural properties, revealing that finer sediments (i.e., mud in overbank areas) are more conductive than coarser ones (i.e., sand in the point-bar bodies). These observations provide information about the spatial distribution of grain size at different depths, showing the occurrence of different vertical grain-size trends within point-bar deposits. Moreover, statistical analyses reveal that the conductivity values in bar deposits are primarily influenced by the grain-size sorting, and subordinately by grain size and composition.&amp;#160;&lt;br&gt;Our findings provide a link between planform evolution of fluvial bends and grain-size distribution within the related bars, with implications to predict subsurface flow propagation within alluvial sedimentary bodies.&amp;#160;&lt;/p&gt;

ANALYSIS OF THE MODERN GRAIN-SIZE COMPOSITION VARIABILITY OF THE ANAPA BAY-BAR BEACH SEDIMENTS

2018 ◽  
Author(s):  
В. Крыленко ◽  
V. Krylenko ◽  
Р. Косьян ◽  
R. Kos'yan ◽  
М. Крыленко ◽  
...  
Keyword(s):  
Grain Size ◽  
Bottom Sediments ◽  
Size Structure ◽  
Size Composition ◽  
Potential Danger ◽  
Grain Size Composition ◽  
Beach Sediments ◽  
Sediment Particles ◽  
Sand Material

The results of realized in 2010 field researches of the spatial and time grain-size structure variability of beach and bottom sediments of the bay-bar Anapskaya southern part are presented in this paper. Irretrievable carrying out of sediment particles to depths more than 7 m intensifies with their size decrease to 0,1 mm. As over 70 % bottom and about 60 % beach sediments are presented by fractions less 0,16 mm on bay-bar Anapskaya southern part, namely at this part there is sand material massive carrying out to depth. Potential danger of the investigated site geosystem degradation is revealed.

scholarly journals Centennial Impacts of the East Asian Summer Monsoon on Holocene Deltaic Evolution of the Huanghe River, China

2021 ◽  
Vol 11 (6) ◽  
pp. 2799
Author(s):  
Yanping Chen ◽  
Wenzhe Lyu ◽  
Tengfei Fu ◽  
Yan Li ◽  
Liang Yi
Keyword(s):  
Grain Size ◽  
Yellow River ◽  
Asian Summer Monsoon ◽  
River Delta ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Sediment Grain Size ◽  
Huanghe River ◽  
Huanghe River Delta ◽  
The Huanghe River

The Huanghe River (Yellow River) is the most sediment laden river system in the world, and many efforts have been conducted to understand modern deltaic evolution in response to anthropological impacts. However, the natural background and its linkage to climatic changes are less documented in previous studies. In this work, we studied the sediments of core YDZ–3 and marine surface samples by grain-size analysis to retrieve Holocene dynamics of the Huanghe River delta in detail. The main findings are as follows: The mean value of sediment grain size of the studied core is 5.5 ± 0.9 Φ, and silt and sand contents are 5.2 ± 2.3% and 8.2 ± 5.3%, respectively, while the variance of clay particles is relatively large with an average value of 86.4 ± 8.5%. All grain-size data can be mathematically partitioned by a Weibull-based function formula, and three subgroups were identified with modal sizes of 61.1 ± 28.9 μm, 30.0 ± 23.9 μm, and 2.8 ± 1.6 μm, respectively. There are eight intervals with abrupt changes in modal size of core YDZ–3, which can be correlated to paleo-superlobe migration of the Huanghe River in the Holocene. Based on these observations, the presence of seven superlobes in the history are confirmed for the first time and their ages are well constrained in this study, including Paleo-Superlobes Lijin (6400–5280 yr BP), Huanghua (4480–4190 yr BP), Jugezhuang (3880–3660 yr BP), Shajinzi (3070–2870 yr BP), Nigu (2780–2360 yr BP), Qikou (2140–2000 yr BP), and Kenli (1940–1780 and 1700–1650 yr BP). By tuning geomorphological events to a sedimentary proxy derived from core YDZ–3 and comparing to various paleoenvironmental changes, we proposed that winter climate dominated Holocene shifts of the Huanghe River delta on millennial timescales, while summer monsoons controlled deltaic evolution on centennial timescales.

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