Geomorphological sedimentary characteristics in the coastal area of Ma river delta, Thanh Hoa province

The coastal area of the Ma river delta is formed by the interaction of continental and marine processes, between neo-tectonic activities and exogenous processes, between natural factors and human activities during the Late Holocene. Using remote sensing and geoscience research methods (granulometry, paleontology, geochemistry, clay mineralogy) and geomorphological studies (geneses, morphology, dynamics) combined with field survey, this coastal area, except the denuded mountainous remnants, could be distinguished into 12 morpho-sedimentary units formed and developed by the dynamic interactions of the river, waves and tides. The units formed by fluvial dynamics include: 1) Point bar is composed of clayey silt and sandy silt, 2) Channel bar composed of silty sand, 3) Levee with the composition of silty sand and 4) The flood plain of silty clay. The Late Holocene evolution of the Ma river delta was dominated by wave dynamics, reflected by a wave-formed association of dunes, interdune swamps and current sand beaches. The wave-formed units include 5) Dune’s sand and silty sand, 6) Back-dune depressions composed of sand silt clay, 7) Beach composed of sand, 8) Lagoon plain of silty clay and 9) Strand plain composed of silty sand. The tide-influenced units include 10) Supratidal flat with the composition of silty clay, 11) Intertidal flat characterized by clay or silty clay interbedded with thin fine sand or silty sand layers, 12) Subtidal flat of sand and silty sand.

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REFLECTION COEFFICIENTS AND BOTTOM LOSSES AT NORMAL INCIDENCE COMPUTED FROM PACIFIC SEDIMENT PROPERTIES

Geophysics ◽

10.1190/1.1440149 ◽

1970 ◽

Vol 35 (6) ◽

pp. 995-1004 ◽

Cited By ~ 44

Author(s):

Edwin L. Hamilton

Keyword(s):

Normal Incidence ◽

Silty Sand ◽

Reflection Coefficients ◽

Silty Clay ◽

Sediment Properties ◽

Compressional Waves ◽

Sea Floor ◽

Sediment Types ◽

The Pacific ◽

Clayey Silt

Rayleigh reflection coefficients and bottom losses of compressional waves at normal incidence on the water‐sediment interface are computed with values of density and velocity measured in sea‐floor sediment samples; main sediment types in three major environments of the Pacific and adjacent areas are included. Some typical average computed values of acoustic bottom loss at normal incidence in db are (1) continental shelf: sands, 8; silty sand, 10; sandy silt, 14; silty clay, 16; (2) abyssal plain: clayey silt, 17; silty clay and clay, 21; and (3) abyssal hill: silty clay and clay, 17. Comparisons with actual measurements at sea by several investigators demonstrate the validity of the approach.

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Evolution of Tidal Flats in the Northern Part of the Po Delta (Italy): A Strategy for Future Buiding-with-Nature Management

10.5194/egusphere-egu21-4169 ◽

2021 ◽

Author(s):

Riccardo Brunetta ◽

Paolo Ciavola

Keyword(s):

Tidal Flat ◽

Central Area ◽

Tidal Flats ◽

Silty Sand ◽

Nature Management ◽

Silty Clay ◽

Po River ◽

Sediment Distribution ◽

Clayey Silt ◽

River Floods

<p>In the period 1950s-60s, the Po river Delta (Northern Italy) was hit by several floods. Agricultural fields were covered by water and many of them remained submerged since. As a consequence of the massive sediment injection into the system, this lead to the birth of new tidal flats around the tip of the Delta. The evolution of these environments over 50 years was studied, as they may be taken as an example for future reconstruction of intertidal areas. The sediment distribution and the morphological evolution of a young tidal flat of about 10 ha located in the Northern part of the Po della Pila branch were studied by undertaking fieldwork since October 2018, including detailed topographic surveys using a UAV, sedimentological analyses, and a study of sediment deposition rates. An extended crevasse splay covers the central part of the flat. The granulometry is predominately fine (Silty clay and Clayey silt), except for the central area, where the sand percentage increases (Loam and Silty sand). This surface distribution is uniform down to ~10 cm; the sand percentage increases instead within the sediment column from ~10 to 25 cm next to the mouths of the channels. The tidal flat experienced a positive sediment budget and it was characterized by higher rates of accretion after the Po river floods. These observations suggest that the tidal channels are fed by sediment from the Po River branch. Orthophotos from the 1950s show that the tidal flat is about 17 - 20 years old and its formation was influenced by human intervention and river floods. The work aims at finally comparing this case study with other tidal flats and salt marshes worldwide characterized by similar and different tidal regimes, to identify the optimal elevation for vegetation to establish and flourish, to support the future restoration of these environments.</p>

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The Mosbeck Site: a Paleoenvironmental Interpretation of the Late Quaternary History of Lake Agassiz Based on Fossil Insect and Mollusk Remains

Quaternary Research ◽

10.1016/0033-5894(72)90037-3 ◽

1972 ◽

Vol 2 (02) ◽

pp. 176-188 ◽

Cited By ~ 19

Author(s):

Allan C. Ashworth ◽

Lee Clayton ◽

William B. Bickley

Keyword(s):

Black Spruce ◽

Late Quaternary ◽

Small Body ◽

Open Water ◽

Fine Sand ◽

Silty Sand ◽

Silty Clay ◽

Lake Agassiz ◽

Fossil Insect ◽

Sand And Gravel

The Mosbeck Site is in the southern part of the Lake Agassiz basin in northwestern Minnesota. The stratigraphic section at the site consists of seven lithologic units, which are from bottom to top (A) unsorted, pebbly, sandy, silty clay, (B) coarse gravel, (C) silty sand, (D) peat, (E) fine sand, (F) interbedded sand and gravel, and (G) unbedded dirty gravel. The lower few centimeters of unit E are unoxidized and contain black spruce and tamarack driftwood, which has been radiocarbon dated at 9940 ± 160 BP (I-3880). Units C-E contain numerous, well-preserved insect and mollusk remains. These fossils have been compared with modern species, and at least 76 insect and 15 mollusk taxa are present. Assuming that their ecological tolerances have changed little in the past 10,000 years, they provide valuable information about the environment of Lake Agassiz. Few of the insects are now found in the region, indicating that the environment has changed. With few exceptions the species present indicate that the climate and vegetation at the time were similar to the present-day climate and vegetation of southeastern Manitoba. The lithology and faunal contents of the sediment are interpreted as follows. Unit A is Late Wisconsinan glacial sediment. Unit B is a lag concentrate formed by wave action during a regressive phase of Lake Agassiz. Unit C is the sediment of a small body of water that formed when the level of Lake Agassiz had dropped below the site. The banks were covered with a spruce forest. Open water gave way to swampy conditions, and unit D was formed. Both units C and D were deposited during the low-water Moorhead Phase of Lake Agassiz. Units E and F are shoreline sediment deposited as the lake level rose, drowning the vegetation. Unit G is modern ditch spoil.

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Late Quaternary Floodplain Sedimentation along the Pomme de Terre River, Southern Missouri

Quaternary Research ◽

10.1016/0033-5894(81)90114-9 ◽

1981 ◽

Vol 15 (1) ◽

pp. 62-76 ◽

Cited By ~ 29

Author(s):

G. Robert Brakenridge

Keyword(s):

Cross Sections ◽

Late Quaternary ◽

Silty Sand ◽

Silty Clay ◽

Red Clay ◽

Pomme De Terre ◽

Clayey Silt ◽

Modern Level ◽

Late Wisconsinan ◽

Floodplain Sedimentation

AbstractNew cross sections and dates from along the Pomme de Terre River clarify the complex local history of valley development and floodplain sedimentation. The observed history begins with a series of ancient bedrock strath terraces that record past bedrock valley positions at 15.5 to more than 58 m above the modern bedrock floor. Each strath is capped by 1–2 m of channel gravel and sand permeated by red clay. Sometime previous to ca. 140,000 yr B.P., a much lower bedrock valley only about 5–6 m above the modern level was excavated. By 140,000 yr B.P., accumulation of red and gray mottled silty clay had commenced, and had reached to 8.5 m above the modern floodplain before 48,900 ± 900 14C yr B.P. Sometime between ca. 49,000 and 45,000 14C yr B.P., erosion caused abandonment of an oxbow meander, and lowered the bedrock valley to about its present depth. Younger yellowish-red and gray mottled silty clay alluvium then began accumulating. This mid-Wisconsinan fill reached to 2.5 m above the modern floodplain sometime before 31,800 ± 1340 14C yr B.P., at which time another erosional phase was in progress. A late Wisconsinan olive clay accumulated between 27,480 ± 1950 and ca. 23,000 14C yr B.P., followed by approximate stability until 13,550 ± 400 14C yr B.P. After stability, an erosional episode began, but by 10,200 ± 330 14C yr B.P., deposition of a distinctive brown clayey silt was underway. This early Holocene fill reached to about the same level as the mid-Wisconsinan fill by 8100 ± 140 14C yr B.P. Erosion occurred between this date and 7490 ± 170 14C yr B.P., but the former floodplain level was rapidly reattained, and was apparently stable until ca. 5000 14C yr B.P. Finally, erosional unconformities and 17 dates from the brown clayey silt, and from younger grayish-brown silty sand underlying the modern floodplain, record subsequent episodes of floodplain erosion at ca. 5000, 2900, 1500 and 350 14C yr B.P. The timing of Pomme de Terre floodplain sedimentary regimes, characterized by net aggradation, erosion, or stability, may have been controlled by climate. In particular, both periods of stability appear to have been coeval to times of strongly zonal upper atmospheric circulation. Intensified zonal circulation would have resulted in less frequent large floods and an increased dominance by floods of small to moderate size. In contrast, there are no obvious parallels to be drawn between this local alluvial history and sea level or glacial outwash induced baselevel changes.

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Holocene sedimentary facies in coastal plain of the Song Ma Delta, Thanh Hoa Province

Vietnam Journal of Earth Sciences ◽

10.15625/0866-7187/41/3/13832 ◽

2019 ◽

Vol 41 (3) ◽

pp. 229-239 ◽

Cited By ~ 1

Author(s):

Vu Van Ha ◽

Doan Dinh Lam ◽

Nguyen Thuy Duong ◽

Nguyen Thi Thu Cuc ◽

Nguyen Minh Quang ◽

...

Keyword(s):

Coastal Plain ◽

Tidal Flat ◽

Time Integration ◽

Sedimentary Facies ◽

Flood Plain ◽

River Delta ◽

Sand Ridge ◽

Silty Clay ◽

14C Dating ◽

Delta Front

The Ma river delta located in the North Central of VietNam is the third largest ones in Vietnam following the Mekong Delta and the Red River Delta. However, there are not many researches on sedimentary. This study aims to determine the Characteristics of the Holocene sedimentary facies in coastal plain of the Song Ma Delta based on observation of sedimentary structure and analysis of grain size, diatom, flora, pollen and 14C dating collected for the drill core (LKTH2 borehole) from the coastal plain of the Song Ma river delta. Research results identify 08 facies consisting 02 facies of transgression period and 06 facies of regression period. During transgression period, 02 facies of tidal flat clayish silt and bay silty clay facies were formed. Of which, tidal flat clayish silt face was formed in 7,883 ± 43 14C yr BP. After the maximum flooding of the sea, the delta was initiated and 06 facies were formed during the regression period i.e. prodelta silty clay, delta front clayish silt, tidal flat sandy - silty clay, sand ridge, lagoonal sandy silty clay, and flood plain silty clay facies. The tidal flat sandy - silty clay facies occurred in 6.951± 38 14Cyr BP caused by sea level fall and the coastline was identified around the LKTH2 bore hole at that time. Integration of sedimentary facies of the sand ridge and lagoonal sandy silty clay facies shows that the Song Ma Delta was dominated by wave process during its evolution.

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Tidal Flat Depositional Response to Neotectonic Cyclic Uplift and Subsidence (1–2 m) as Superimposed on Latest-Holocene Net Sea Level Rise (1.0 m/ka) in a Large Shallow Mesotidal Wave-Dominated Estuary, Willapa Bay, Washington, USA

Journal of Geography and Geology ◽

10.5539/jgg.v10n1p109 ◽

2018 ◽

Vol 10 (1) ◽

pp. 109 ◽

Cited By ~ 1

Author(s):

Curt D. Peterson ◽

Sandy Vanderburgh

Keyword(s):

Sea Level Rise ◽

Sea Level ◽

Tidal Flat ◽

Late Holocene ◽

Columbia River ◽

Small Rivers ◽

Intertidal Flat ◽

Sedimentation Rates ◽

Lateral Migration ◽

Willapa Bay

The late-Holocene record of tidal flat deposition in the large shallow Willapa Bay estuary (43 km in length), located in the Columbia River Littoral Cell (CRLC) system (160 km length), was investigated with new vibracores (n=30) and gouge cores (n=8), reaching 2–5 m depth subsurface. Reversing up-core trends of muddy sand to peaty mud deposits in marginal tidal flat settings demonstrate episodic submergence events resulting from cyclic tectonic uplift and subsidence (1–2 m) in the Cascadia subduction zone. These short-term reversals are superimposed on longer-term trends of overall sediment coarsening-up, which represent the transgression of higher-energy sandy tidal flats over pre-existing lower-energy tidal flat mud and peaty mud deposits in late-Holocene time. Fining-up trends associated with channel lateral migration and accretionary bank deposition occurred only infrequently in the broad intertidal flats of Willapa Bay. Vibracores and gouge cores were dated by 14C (n=16) and paleo-subsidence event contacts (n=17). Vibracore median probability 14C ages ranged from 0 to 6,992 yr BP and averaged 2,174 yr BP. Dated sample ages and corresponding depths of tidal flat deposits yield net sedimentation rates of 0.9–1.2 m ka-1, depending on the averaging methods used. Net sedimentation rates in the intertidal flat settings (~1.0 m ka-1) are comparable to the rate of net sea level rise (~1.0 m ka-1), as based on dated paleo-tidal marsh deposits in Willapa Bay. Reported modern inputs of river sand (total=1.77x104 m3 yr-1), from the three small rivers that flow into Willapa Bay, fall well short of the estimated increasing accommodation space (1.9x105 m3 yr-1) in the intertidal (MLLW-MHHW) setting (1.9x108 m2 surface area) during the last 3 ka, or 3.0 m of sea level rise. The under-supply of tributary sand permitted the influx of littoral sand (1.1x105 m3 yr-1) into Willapa Bay, as based on the net sedimentation rate (~1.0 m ka-1) and textural composition (average 60 % littoral sand) in analyzed core sections (n=179). The long-term littoral sand sink in Willapa Bay’s intertidal setting (55 % of total estuary area) is estimated to be about 5 % of the Columbia River supply of sand to the CRLC system, and about 30% relative to the littoral sand accumulated in barrier spits and beach plains during late-Holocene time. A 2.0 m rise in future sea level could yield a littoral sand sink of 2.2x108 m3 in the Willapa Bay intertidal setting, resulting in an equivalent shoreline retreat of 600 m along a 50 km distance of the barrier spit and beach plains that are located adjacent to the Willapa Bay tidal inlet. Willapa Bay serves as proxy for potential littoral sand sinks in other shallow mesotidal estuary-barrier-beach systems around the world following future global sea level rise.

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Evaluation of Salt-water Intrusion in the Coastal Area of Igbokoda, Southwestern Nigeria

International Journal of Scientific Research and Management ◽

10.18535/ijsrm/v6i1.g01 ◽

2018 ◽

Vol 6 (01) ◽

Author(s):

Talabi A. O ◽

Ajayi C. A ◽

Afolagboye L. O ◽

Oyedele A. A ◽

Ojo O. F ◽

...

Keyword(s):

Coastal Area ◽

Salt Water ◽

Silty Sand ◽

High Resistivity ◽

Salt Water Intrusion ◽

Southwestern Nigeria ◽

Major Threat ◽

Sandy Clay ◽

The World ◽

Electrical Sounding

Saltwater intrusion into the coastal aquifer has long been recognized as a major threat to groundwater quality around the world. Groundwater evaluation of salt water intrusions in Igbokoda coastal area, southwestern Nigeria was carried out employing combined Horizontal Profiling and Vertical electrical sounding. Two traverses each with two sounding points were occupied. The result from the survey revealed 4 to 5 major layers comprising the unconsolidated silty sand and sandy clay (overburden), clayey zone, consolidated sand zone, partly intruded salt water intruded sandy clay zone and salt water intruded clay zone. The curves were the complex types KQH, KHA, QH and HKH curves. The overburden has resistivity that ranged from 253 to 1316.7Ω-m, thickness that ranged from 0.2 m to 7m. The clayey zone had resistivity of 846.0 Ω-m and thickness of 4m. The consolidated sand zone had resistivity that ranged from 2848.7 to 2865.7Ω-m and thickness that ranged between 4 and 21m. The partly intruded salt water zone is characterized by resistivity that varies between 18.4Ω-m and 93.0Ω-m and thickness of about 7-25m. The salt water intruded zone is characterized by resistivity that ranges between 4.1Ω-m and 9.7Ω-m and thickness of 4-48m. The partly-salt water intruded zones and salt water intruded zone were characterized with low resistivity while the high resistivity zones of consolidated sand layer constitute fresh water bearing zone that could serve as boreholes in the study area.

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Clay Minerals Variations in Quaternary Sediments of Basrah City-Iraq

Earth Science Research ◽

10.5539/esr.v6n2p41 ◽

2017 ◽

Vol 6 (2) ◽

pp. 41

Author(s):

Mohanad Hamid Al-Jaberi

Keyword(s):

Clay Minerals ◽

Mineralogical Composition ◽

Silty Sand ◽

Recent Sediment ◽

Quaternary Sediments ◽

Marine Transgression ◽

Fine Grain ◽

Clayey Silt ◽

Marine Facies ◽

Mixed Layers

Mineralogical and chemical analysis of two well cutting in quaternary sediments at Basrah city. This study have been focused on the quaternary clay minerals variations which give a clear indication to marine transgression and or / regression in Hammar formation. Kaolinite, Illite, Palygoreskite, Illite-Palygorestike mixed layer, Chlorite, Montmorillonite, Vermiculte, and mixed layers of Illite- Smectite are the most quantitatively important phyllosilicates in soil studies in both boreholes. The mineralogical composition of cutting sediments shows significant variability in the different size fractions and depth distribution. Chlorite and kaolinite minerals were increase in the fine grain size especially in the clayey silt, whereas montmoriolllinite and vermiculite minerals were increase in coarse grains especially in silty sand texture. Kaolinite decrease in abundance with depth, which give indicative of a transition from non-marine in quaternary recent sediment ( fresh or brackish water silt) to marine facies in quaternary Hammar formation ( marine shelly silt) during last transgression of quaternary. Palygoreskite mineral percentages increasing at depths 27 and 28 meter , after decreased at 30, 32, 35 , and 40 m respectively , which give data indication that early quaternary marine transgression happened in 32m , and center of quaternary marine transgression detected in 27 and 28 meters , while late marine transgression detected in 17 m , and all of these represent by Hammar formation. Soil ageing also caused to downward increase of montmorillonite suggest to climate became more arid during the early quaternary. Variations ratio of montmorillonite versus kaolinite can be indicated to climatic fluctuation. Illite-Semectite featured indicates changes in both sediment source and paleoclimate. Illite transformation for Illite-Palygoreskite mixed layers with ageing. Vermiculite has strong susceptibility to increase with age. SiO₂, Al₂O₃, CaO, MgO, K₂O, and Fe₂O₃ were the major oxides that identified in present study and used as indicated of clay minerals in studied sediments.

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Holocene Environments in Northeast Africa

The Oxford Handbook of Ancient Nubia ◽

10.1093/oxfordhb/9780190496272.013.4 ◽

2021 ◽

pp. 62-78

Author(s):

Martin Williams

Keyword(s):

Late Holocene ◽

Flood Plain ◽

Low Flow ◽

Archaeological Record ◽

Human Occupation ◽

Complex Interactions ◽

Maar Lake ◽

Low Levels ◽

White Nile ◽

Ne Africa

This chapter provides an overview of the geography, hydrology, and climate of NE Africa, with particular reference to the complex interactions between river regime, climate, the biota, and human settlement. During the Early (11.7–8.2 ka) and Middle Holocene (8.2–4.2 ka) the climate was far less arid than today across the Nile basin, including Nubia, albeit with sporadic dry phases. Climatic desiccation set in during the Late Holocene (4.2 ka to present), with minor wet phases. Intervals when the Nile flow regime was apparently shifting from high to low flow and flood plain incision have provisional ages of ca. 8.15–7.75 ka, 6.4–6.15 ka, 5.7–5.45 ka, 4.7–4.25 ka, 3.35–2.9 ka, 2.8–2.55 ka, and 1600 ce. In the Kerma area of Nubia there were two periods of relatively dense human occupation in the earlier part of the Holocene from 10 ka to 8 ka and from 7 ka to 6 ka, with two significant gaps in the archaeological record at 7.5–7.1 ka and 6.0–5.4 ka, that coincided with very low levels in Lake Challa, a maar lake on the eastern flank of Mt Kilimanjaro, near the Ugandan headwaters of the White Nile.

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