Articoli di riviste: "Sedimentation and depositions"

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Ahmadov, T. "THE ROLE OF COSMIC DUST IN THE FORMATION OF STRONG REFLECTIVE BOUNDARIES (ON THE EXAMPLE OF INDIVIDUAL AREAS OF AZERBAIJAN)". National Association of Scientists 2, n. 75 (1 febbraio 2022): 06–11. http://dx.doi.org/10.31618/nas.2413-5291.2022.2.75.558.

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The paper underlines that reserves in anticline traps are exhausting both in Azerbaijan and around the globe and in this respect the priority today is exploration for hydrocarbon resources in non-anticline traps, which are formed with a certain role of non-depositions or in other words - breaks in sedimentation process. In this respect, it is natural that in the recent years the geoscientists pay a close attention to researches on non-anticline traps and non-depositions, since they were not covered by specific studies until now. It should be noted, that studies held at the “Geophysics” Department of Azerbaijan State Oil and Industry University are some kind of exception. In this paper, results of some studies are given, including outlined boundaries of unconformities, related to nondepositions under various seismogeological conditions in onshore and offshore areas. It has been also indicated, that no specific studies of non-depositions by use of seismic survey have been held in Azerbaijan. This paper is devoted to outlining and tracking of boundaries related to breaks in sedimentation process analyzed by use of various seismic survey data acquired in various oil and gas regions of Azerbaijan. First of all, the paper considers the brief geological and geophysical characteristics of non-depositions and it is noted that a special role in their study is attributed to high-resolution seismic survey and electric survey. It is specially underlined that under the non-depositions the geoscientists mean the absence of terrestrial depositions and outlining and tracing of regional and reference seismic horizons are not complicated task. According to the latest studies, during the periods of global and local breaks in sedimentation process, the depositions of terrestrial origin are absent, however deposition of cosmic dust is continuously going on and this has been proved by various studies. The paper also indicated the role of some researchers in studies of depositions of cosmic origin and their reflections in seismic data. The results of studies of depositions of cosmic origin by use of modeling held in Azerbaijan have been also displayed.

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Bai, Shu Zhan, Shuai Guo Lang, Ke Ping Yuan, Yang Liu e Guo Xiang Li. "Experimental Study of Urea Depositions in Urea-SCR System". Advanced Materials Research 937 (maggio 2014): 74–79. http://dx.doi.org/10.4028/www.scientific.net/amr.937.74.

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Avoiding the urea deposition in the exhaust stream is one of the basic requirements for SCR system normal application. Unreasonable structure design, machining and installation position all could lead to urea crystallization on the wall of exhaust pipe and the front end surface of the catalyst, in addition, unreasonable control strategy also could deteriorate this phenomenon. The components of the urea depositions are the urea and cyanuric acid analyzed by thermogravimetry - FTIR technology. The integrated injector mounting is designed to alleviate the urea crystallization based on analysis results. The engine test and the vehicle road test are all shown that the optimal structural design and calibration strategies could avoid crystallization and sedimentation effectively in the exhaust system.

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Middelkoop, H. "Heavy-metal pollution of the river Rhine and Meuse floodplains in the Netherlands". Netherlands Journal of Geosciences - Geologie en Mijnbouw 79, n. 4 (dicembre 2000): 411–27. http://dx.doi.org/10.1017/s0016774600021910.

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AbstractThe embanked floodplains of the lower Rhine river in the Netherlands contain large amounts of heavy metals, which is a result of many years of deposition of contaminated overbank sediments. The metal pollution varies greatly between the various floodplain sections as well as in vertical direction within the floodplain soil profiles. The present contribution describes the key processes producing the spatial variability of the metal pollution in floodplain soils: (1) spatial patterns of the concentrations and deposition of Cd, Cu, Pb and Zn during a single flood, which have been determined from samples collected after a high-magnitude flood event; (2) the pollution trends of the lower Rhine over the past 150 years, which were reconstructed on the basis of metal concentrations in sediments from small ponds within the floodplain area. During the flood the largest metal depositions (0.03 g/m2 Cd, 0.7 g/m2 Cu, 1.1 g/m2 Pb and 5.0 g/m2 Zn for the Rhine) occurred along the natural levees, decreasing to about one third of these values at larger distance from the river. Deposition of heavy metals occurred since the end of the nineteenth century. Periods of maximum pollution occurred in the 1930s and 1960s, when Cu, Pb and Zn concentrations were about 6–10 times as high as background values.The resulting metal distribution in the floodplain soil profiles is illustrated by means of typical examples. Maximum metal concentrations in floodplain soils vary from 30 to 130 mg/kg for Cu, from 70 to 490 mg/kg for Pb, and from 170 to 1450 mg/kg for Zn. The lowest metal pollution is found in the distal parts of floodplain sections with low flooding frequencies, where average sedimentation rates have been less than about 5 mm/a. The largest metal accumulations occur in low-lying floodplain sections where average sedimentation rates have been more than 10 mm/a.

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Abou Seedo, Kholoud, Mohammad S. Abido, Ahmed Salih e Asma Abahussain. "Structure and Composition of Mangrove Associations in Tubli Bay of Bahrain as Affected by Municipal Wastewater Discharge and Anthropogenic Sedimentation". International Journal of Biodiversity 2017 (19 dicembre 2017): 1–9. http://dx.doi.org/10.1155/2017/2084256.

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The effects of municipal wastewater discharge and anthropogenic sedimentation on the structure and composition of gray mangrove (Avicennia marina (Forsk.) Vierh.) communities along Tubli Bay coastlines in Bahrain were investigated. Growth and regeneration of mangrove were measured, and its community was characterized. Sediment profile was analyzed for texture, pH, and salinity. Mangrove area covered by sand depositions was measured using Google Earth Pro. ANOVA and regression tests were employed in the analysis of the data. Results indicated that mangrove overwhelmingly dominated plant community in the study area, which was zoned by a community of other salt-tolerant species. Three main habitats exist in the study area with high similarity in their floristic composition. Species richness and the number of habitats were low due to the aridity and high sediment salinity. The dilution effect of the secondary treated wastewater had a favorable effect on height and diameters of mangrove trees. However, no differences were observed in leaf area index, basal area, and density of mangrove. The long-term accumulation of anthropogenic sedimentation had a detrimental effect on the mangrove community, expressed in swath death of mangrove trees due to root burials and formation of high topography within the community boundaries.

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Cheremisska, O. M., e Yu V. Cheremissky. "Lithofacial and paleogeographic analysis of the Burdigallian-Langhian formations of the Ukrainian Carpathian Foredeep". Journal of Geology, Geography and Geoecology 28, n. 1 (16 aprile 2019): 19–28. http://dx.doi.org/10.15421/111903.

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This paper addresses issues related to the complexity of the geological structure of the Burdigallian-Langhian sediments of the Stebnyk suite, which wereformed in the Carpathian segment of Paratethys. The correlation of stratigraphic sections, based on a detailed description of the most complete sediments of the indigenous outcrops of the Stebnyk suite in the Sambir Unit of the Pre-Carpathian Foredeep, has been carried out. It was established that the sediments belong to a single tectono-sedimentation cyclic, the formation of which began with the deposition of red-coloured sediments and ended with the deposition of salt-bearing formations, which indicates the final closure of the Paratethys. A series of lithological columns was constructed taking into account the disjunctive and plicating faults, which allowed us to derive the true thickness of the Stebnyk suite deposits and determine its lithofacial structure. The results obtained became the basis for the construction of a lithological scheme for the distribution of lithofacies and a paleooceanographic sedimentation model of the research area. The aim of this work is to create a reconstruction of the environment of sedimentation in the Burdigallian-Langhian Age in the Sambir Unit of the Inner part of the Pre-Carpathian Foredeep. To obtain the results, the actual material obtained during the field observations was analyzed with the help of a complex of lithology-facial, geodynamical and petrographic methods. Due to the absence of the reliable paleontological data on deposits of the Miocene Stebnyk suite of the PreCarpathian basin, an attempt was made to partition the Stebnyk sedimentary sequence on lithological and formation features, basedon the author's research and with incorporation of new materials of paleooceanography of the Carpathian segment of the Paratethys. On the basis of paleooceanographic data, connected with formation of sedimentary strata of Stebnyk suite (Carpathian basin), the latter can be attributed to the red-coloured formation of foothill plains and deltas. Taking into account the data of the researchers and their own observations, one can come to the conclusion that the age of the sediments, mapped on existing geological maps as Vorotyshcha suite in considerable areas of Sambir Unit (near the villages of Krasne, Pidlyvche, Lysovychi) is questionable. This conception required the stratification of deposits formed on the stage of sedimentogenesis in the Miocene within the studied segment of the Central Paratethys. For the first time for depositions of this age, the scheme of the palaeoceanographic situation and a lithological-facial model of the sedimentation environment with the reduction of the true thickness of sediments was constructed. The Burdigallian-Langhian deposits were formed under conditions of lacustrine-alluvial plains of arid climate, symbolizing the final closure of the Central Paratethys. The presence of a detailed model for the formation of Burdigallian-Langhian deposits allows us to identify a number of criteria for the search for minerals.

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Gale, Luka. "Microfacies analysis of the Upper Triassic (Norian) "Bača Dolomite": early evolution of the western Slovenian Basin (eastern Southern Alps, western Slovenia)". Geologica Carpathica 61, n. 4 (1 agosto 2010): 293–308. http://dx.doi.org/10.2478/v10096-010-0017-0.

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Microfacies analysis of the Upper Triassic (Norian) "Bača Dolomite": early evolution of the western Slovenian Basin (eastern Southern Alps, western Slovenia)The Slovenian Basin represents a Mesozoic deep-water sedimentary environment, situated on the southern Tethyan passive margin. Little is known about its earliest history, from the initial opening in the Carnian (probably Ladinian) to a marked deepening at the beginning of the Jurassic. The bulk of the sediment deposited during this period is represented by the Norian-Rhaetian "Bača Dolomite", which has, until now, been poorly investigated due to a late-diagenetic dolomitization. The Mount Slatnik section (south-eastern Julian Alps, western Slovenia) is one of a few sections where the dolomitization was incomplete. Detailed analysis of this section allowed us to recognize eight microfacies (MF): MF 1 (calcilutite), MF 2 (pelagic bivalve-radiolarian floatstone/wackestone to rudstone/packstone), MF 3 (dolomitized mudstone) with sub-types MF 3-LamB and MF 3-LamD (laminated mudstone found in a breccia matrix and laminated mudstone found in thin-bedded dolomites, respectively) and MF 3-Mix (mixed mudstone), MF 4 (bioturbated radiolarian-spiculite wackestone), MF 5 (fine peloidal-bioclastic packstone), MF 6 (very fine peloidal packstone), MF 7 (bioclastic wackestone) and MF 8 (crystalline dolomite). The microfacies and facies associations indicate a carbonate slope apron depositional environment with hemipelagic sedimentation punctuated by depositions from turbidites and slumps. In addition to the sedimentary environment, two "retrogradation-progradation" cycles were recognized, each with a shift of the depositional setting from an inner apron to a basin plain environment.

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Situmorang, Dr B. "Seismic Stratigraphy Of The Makassar Basin". Scientific Contributions Oil and Gas 10, n. 1 (14 aprile 2022): 3–38. http://dx.doi.org/10.29017/scog.10.1.895.

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Seismic reflection profiles from the Makassar basin have been analysed in terms of seismic stratigraphy. Systematic patterns of reflection terminations indicate the existence of at least three surfaces of discontinuity across the profiles-designated in order of superposition as C1, C2 and C3 - which define the boundaries of four seismic sequences, ie. :- seismic sequence I : topped by C1- seismic sequence II : the interval between C1 and C2- seismic sequence III : the interval between C2 and C3- seismic sequence IV : the interval between Cz and the sea floor Seismic sequence II is dominated by basin slope and basin floor seismic facies whereas seismic sequences II and IV consist of mainly shelf and shelf margin seismic facies. Correlation of seismic sequences with well data facilitates the exposition of basin development, The Late Cretaceous-early Tertiary regional uplift and erosion produced a major unconformity C1, upon which the transgressive facies of seismic sequence II was deposited. A lowstand of sea level due to the so-called intra-Mio- cene orogeny occurred in the upper Early Miocene and produced the C2. Deposition of seismic sequence III is marked by a relative rise of sea level, probably followed by another lowstand of sea level during Mio-Pliocene which formed the C3. The final event is an overall transgression and deposition of seismic sequence IV, with a possible minor lowstand of sea level in Pliocene-Recent, The occurrence of basin slope and basin floor seismic facies within seismic sequence II suggests that in the pre-Lower Miocene, basin subsidence was slightly greater than the rate of depositions. Since Lower Miocene both subsidence and sedimentation rates were equal and the deposition of shelf and shelf margin seismic facies of seismic sequences III and IV was prevailed in the basin.

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Nwaoha, Adanma Florence, Camelita Chima Ohaeri e Ebube Charles Amaechi. "Prevalence of diarrhoea, and associated risk factors, in children aged 0-5 years, at two hospitals in Umuahia, Abia, Nigeria". UNED Research Journal 9, n. 1 (14 marzo 2017): 7–14. http://dx.doi.org/10.22458/urj.v9i1.1672.

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Diarrhoea is the second leading cause of infectious morbidity and mortality in children under five years of age. This study aimed at identifying the most common parasites and potential risk factors for diarrhoea among children 0-5 years attending Abia State Specialist hospital and Federal Medical Centre, Umuahia, in south eastern Nigeria. We used 400 faecal samples from children with diarrhoea –and 200 without– in combination with hospital-based case control and a questionnaire Stool samples were processed with direct normal saline and formal-ether sedimentation method for parasitological studies. More males than females were infected in nearly all age groups in both diarrhoeal and control groups (X2=23.04, df=1, P<0.05: X2=11.52, df=1, P<0.05 respectively). Amachara had more infections (X2=0.15, df=1, P< 0.05). January had the highest rate of infection (22.5%). Main clinical features were watery depositions over 3 times a day, diarrhoea lasting for days, fever, vomiting, and dehydration. Mothers learned about the problem through health workers, television and in medical centers. Risk correlated with mother’s education, occupation, latrine type, waste water disposal, hand washing, kitchen cleaning; sources and storage of water; and bottle milk (P< 0.05).Ignorance greatly contributed to the spread of parasitic disease in the area: the government should improve education and other strategies to alleviate the spread of the disease..

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Bhuju, DR, S. Sharma, PK Jha e NP Gaire. "Scientific Discourse of Lakes in Nepal". Nepal Journal of Science and Technology 13, n. 2 (8 marzo 2013): 147–58. http://dx.doi.org/10.3126/njst.v13i2.7728.

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Over 5,000 standing water bodies, including those <1 ha and spread in 74 districts of Nepal have been scanned on the topographic sheets (scale of 1:125,000). Majority of these lakes or ponds are either in the high altitudes (above 3,000 m) or in lowland Tarai (below 500 m). In a literature review we found over 163 research studies conducted since the first study of lakes in 1969 in Khumbu region, majority being at the initiative of national academia, their faculties and graduate students. However, a complete inventory of Nepal’s lakes is still lacking. Their characteristics and distinction from wetlands are also to be defined as the existing laws and rules do not protect lakes or ponds categorically, rather they are blanketed under wetlands and/or other river like water resources. Research observations have shown that acid depositions are the most likely source of pollution affecting high altitude lakes in the Himalayan regions during spring. Their value as religious sites has also caused anthropogenic alteration in nutrient concentrations and biological assemblages of the lake. Encroachment to the lakes/ponds is rampant to which the natural processes of sedimentation, alien species invasion or any kind of obliteration become supportive. Capacity building, knowledge generation and threat management are vital to protect these natural heritages from untimely demise. Nepal Journal of Science and Technology Vol. 13, No. 2 (2012) 147-158 DOI: http://dx.doi.org/10.3126/njst.v13i2.7728

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Wang, L. C., H. Behling, T. Q. Lee, H. C. Li, C. A. Huh, L. J. Shiau e Y. P. Chang. "Late Holocene environmental reconstructions and the implications on flood events, typhoon patterns, and agriculture activities in NE Taiwan". Climate of the Past Discussions 10, n. 3 (5 maggio 2014): 1977–2009. http://dx.doi.org/10.5194/cpd-10-1977-2014.

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Abstract. In this study, we reconstructed the paleoenvironmental changes from a sediment archive of the floodplain lake in Ilan Plain of NE Taiwan on multi-decadal resolution for the last ca. 1900 years. On the basis of pollen and diatom records, we evaluated the record of past vegetation, floods, typhoons and agriculture activities of this area, which is sensitive to the hydrological conditions of the West Pacific. High sedimentation rates with low microfossil preservations reflected multiple flood events and humid climatic conditions during 100–1400 AD. A shortly interrupted dry phase can be found during 940–1010 AD. The driest phase corresponds to the Little Ice Age phase 1 (LIA1, 1400–1620 AD) with less disturbance by flood events, which enhanced the occurrence of wetlands (Cyperaceae) and diatom depositions. Humid phases with frequent typhoons are inferred by high percentages of Lagerstroemia and high ratios of planktonic/benthic diatoms, respectively, during 500–700 AD and Little Ice Age phase 2 (LIA2, 1630–1850 AD). The occurrences of cultivated Poaceae (Oryza) during 1250–1300 AD and the last ~400 years, reflect agriculture activities, which seems to implicate strongly with the environmental stability. Finally, we found flood events which dominated during the El Niño-like stage, but dry events as well as frequent typhoon events happened during the La Niña-like stage. After comparing our results with the reconstructed proxy for tropical hydrological conditions, we suggested that the local hydrology in coastal East Asia were strongly affected by the typhoon-triggered heavy rainfalls which were influenced by the variation of global temperature, expansion of the Pacific warm pool and intensification of ENSO events.

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Lee, S. S., e J. E. Penner. "Aerosol effects on ice clouds: can the traditional concept of aerosol indirect effects be applied to aerosol-cloud interactions in cirrus clouds?" Atmospheric Chemistry and Physics Discussions 10, n. 4 (21 aprile 2010): 10429–62. http://dx.doi.org/10.5194/acpd-10-10429-2010.

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Abstract. Cirrus clouds cover approximately 20–25% of the globe and thus play an important role in the Earth's radiation budget. This indicates that aerosol effects on cirrus clouds can have a substantial impact on the variation of global radiative forcing if the ice-water path (IWP) changes. This study examines the aerosol indirect effect (AIE) through changes in the IWP for a cirrus cloud case. We use a cloud-system resolving model (CSRM) coupled with a double-moment representation of cloud microphysics. Intensified interactions among the cloud ice number concentration (CINC), deposition and dynamics play a critical role in the IWP increases due to aerosol increases. Increased aerosols lead to increased CINC, providing increased surface area for water vapor deposition. The increased deposition causes depositional heating which produces stronger updrafts, and leads to the increased IWP. The conversion of ice crystals to aggregates through autoconversion and accretion plays a negligible role in the IWP responses to aerosols, as the sedimentation of aggregates. The sedimentation of ice crystals plays a more important role in the IWP response to aerosol increases than the sedimentation of aggregates, but, not more important than the interactions among the CINC, deposition and dynamics.

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Liverman, David G. E. "Sedimentation in ice-dammed Hazard Lake, Yukon". Canadian Journal of Earth Sciences 24, n. 9 (1 settembre 1987): 1797–806. http://dx.doi.org/10.1139/e87-171.

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"Hazard Lake," located in Kluane National Park, the Yukon, is an ice-dammed lake formed in 1966 by the surge of the Steele Glacier. Since 1975 it has drained annually by means of a subglacial tunnel. During July 1979, observations were made of lake processes before drainage and of sections described in the lake bottom after drainage. Three facies associations are believed to represent prelake, stable lake, and annual draining phases. Gravel commonly found at the base of sections represents deposition in a braided fluvial system prior to 1966. Lake sediments deposited between 1966 and 1975 are dominantly graded laminated silt deposited by turbid underflow from the major inflow stream. Lamination is probably caused by diurnal underflow events or daily variation in strength of underflow. No "winter" clay component of varved sediments is observed. During drainage a regressive sequence is deposited as the lake level drops, with sand-dominated sediments overlapping laminated silt where the main inflow stream enters the lake. This is followed by local fluvial deposition along the course of the reestablished stream. During filling a transgressive sequence is deposited as the lake level rises. Sand-dominated deltaic sedimentation is followed by deposition from underflow, resulting in laminated and massive silt and clay. These fine-grained facies separate sand facies and demark individual filling events but are easily eroded. Thus it is not possible to identify the effects of each individual drainage–filling cycle in the sediments. After drainage the lake remains empty until the next melt season, during which time a braided stream is established in the lake basin, depositing sands and gravels and eroding lake sediments.

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Lee, S. S., e J. E. Penner. "Aerosol effects on ice clouds: can the traditional concept of aerosol indirect effects be applied to aerosol-cloud interactions in cirrus clouds?" Atmospheric Chemistry and Physics 10, n. 21 (4 novembre 2010): 10345–58. http://dx.doi.org/10.5194/acp-10-10345-2010.

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Abstract. Cirrus clouds cover approximately 20–25% of the globe and thus play an important role in the Earth's radiation budget. Therefore the effect of aerosols on cirrus clouds can have a substantial impact on global radiative forcing if either the ice-water path (IWP) and/or the cloud ice number concentration (CINC) changes. This study examines the aerosol indirect effect (AIE) through changes in the CINC and IWP for a cirrus cloud case. We use a cloud-system resolving model (CSRM) coupled with a double-moment representation of cloud microphysics. Intensified interactions among CINC, deposition and dynamics play a critical role in increasing the IWP as aerosols increase. Increased IWP leads to a smaller change in the outgoing LW radiation relative to that for the SW radiation for increasing aerosols. Increased aerosols lead to increased CINC, providing increased surface area for water vapor deposition. The increased deposition causes depositional heating which produces stronger updrafts, and leads to the increased IWP. The conversion of ice crystals to aggregates through autoconversion and accretion plays a negligible role in the IWP response to aerosols, and the sedimentation of aggregates is negligible. The sedimentation of ice crystals plays a more important role in the IWP response to aerosol increases than the sedimentation of aggregates, but not more than the interactions among the CINC, deposition and dynamics.

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Apak, S. N., W. J. Stuart e N. M. Lemon. "COMPRESSIONAL CONTROL ON SEDIMENT AND FACIES DISTRIBUTION SW NAPPAMERRI SYNCLINE AND ADJACENT MURTEREE HIGH, COOPER BASIN". APPEA Journal 35, n. 1 (1995): 190. http://dx.doi.org/10.1071/aj94013.

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The northeast-trending Nappamerri Syncline and its flanking high to the southeast, the Murteree-Nappacoongee (NM) Trend, show structural development throughout the deposition of the Permo-Triassic Cooper Basin sequences. Pre-existing topography, such as around Moomba, influenced early depositional patterns within the area. Rates of sedimentation were influenced by the rate of uplift of source areas around the basin, largely as a consequence of buckling. Periods of active tectonism resulted in non-deposition and stripping of sediments from uplifted blocks while deposition continued in deeper areas. Hangingwall blocks, pushed up along reverse faults, strongly influenced the areas of sedimentation and the facies being deposited. This is particularly evident along the NM Trend. Phases of uplift were immediately followed by increased sedimentation where fluvial deposition dominated. The effect of displacement along the northwest-trending basement lineaments was to subdivide the northeast trends into compartments which contain similar facies within each time slice. Adjacent compartments may display different facies and different tectonic histories. An inversion episode, particularly evident in the Big Lake/Moomba area, resulted in a reversal of the depocentre and was related to phases of Sakmarian compression.Facies distribution and sandstone percentage maps of the chronostratigraphic units of the Patchawarra Formation suggest that a northeast-trending major channel system entered this part of basin along the NW edge of the Murteree area.

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Wood, Fletcher M., Jerry A. Yamamuro e Poul V. Lade. "Effect of depositional method on the undrained response of silty sand". Canadian Geotechnical Journal 45, n. 11 (novembre 2008): 1525–37. http://dx.doi.org/10.1139/t08-079.

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The results from a laboratory experimental study on silty sand are presented. Undrained triaxial compression tests were performed on Nevada sand containing nonplastic silt. All specimens underwent monotonic loading after isotropic consolidation to 25 kPa. Various depositional techniques were used to create specimens to compare their stress–strain behavior within three separate density ranges and three different silt contents. As density increased, the effect of the depositional method on the undrained behavior decreased. The influence of the depositional method on specimen behavior also was found to increase with silt content, particularly at lower densities. These findings therefore are of special interest with regard to laboratory testing for the purpose of characterizing liquefaction potential, where loose, silty sands may be encountered. A description and analysis of five different depositional techniques is provided. These methods include: dry funnel deposition, water sedimentation, slurry deposition, mixed dry deposition, and air pluviation. The results of the undrained testing are analyzed using void ratio after consolidation and silt content as the bases of comparison.

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Engkilde, Michael, e Finn Surlyk. "Shallow marine syn-rift sedimentation: Middle Jurassic Pelion Formation, Jameson Land, East Greenland". Geological Survey of Denmark and Greenland (GEUS) Bulletin 1 (28 ottobre 2003): 813–63. http://dx.doi.org/10.34194/geusb.v1.4690.

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The Middle Jurassic Pelion Formation – Fossilbjerget Formation couplet of Jameson Land, East Greenland, is a well-exposed example of the Middle Jurassic inshore–offshore successions characteristic of the rifted seaways in the Northwest European – North Atlantic region. Early Jurassic deposition took place under relatively quiet tectonic conditions following Late Permian – earliest Triassic and Early Triassic rift phases and the Lower Jurassic stratal package shows an overall layer-cake geometry. A long-term extensional phase was initiated in Middle Jurassic (Late Bajocian) time, culminated in the Late Jurassic (Kimmeridgian–Volgian), and petered out in the earliest Cretaceous (Valanginian). The Upper Bajocian – Middle Callovian early-rift succession comprises shallow marine sandstones of the Pelion Formation and correlative offshore siltstones of the Fossilbjerget Formation. Deposition was initiated by southwards progradation of shallow marine sands of the Pelion Formation in the Late Bajocian followed by major backstepping in Bathonian–Callovian times and drowning of the sandy depositional system in the Middle–Late Callovian. Six facies associations are recognised in the Pelion–Fossilbjerget couplet, representing estuarine, shoreface, offshore transition zone and offshore environments. The north–southtrending axis of the Jameson Land Basin had a low inclination, and deposition was sensitive to even small changes in relative sea level which caused the shorelines to advance or retreat over tens to several hundreds of kilometres. Eight composite sequences, termed P1–P8, are recognised and are subdivided into a total of 28 depositional sequences. The duration of the two orders of sequences was about 1–2 Ma and 360,000 years, respectively. The Upper Bajocian P1–2 sequences include the most basinally positioned shallow marine sandstones, deposited during major sealevel lowstands. The lowstands were terminated by significant marine flooding events, during which sandstone deposition was restricted to northern, more proximal parts of the basin. The Upper Bajocian – Middle Bathonian P3–4 sequences show an overall progradational stacking pattern. The sequence boundary at the top of P4 marks a significant shift in stacking pattern, and the Upper Bathonian – Middle Callovian P5–8 sequences show large-scale backstepping, terminating in a widespread condensed succession at the distal, southern end of the basin. The largescale backstepping was governed by combined tectonically-induced subsidence, reflecting increased rates of extension, and eustatic sea-level rise. The depositional trends of the Pelion Formation – Fossilbjerget Formation couplet provide a well-exposed analogue to contemporaneous subsurface deposits which form major hydrocarbon reservoirs on the west Norway shelf, and in the Northern North Sea.

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Devi, Salam Ranjeeta. "Geochemistry, Depositional and Tectonic setting of the Barail Group of the Indo-Myanmar Ranges". Journal of The Indian Association of Sedimentologists 38, n. 1 (30 giugno 2021): 13–22. http://dx.doi.org/10.51710/jias.v38i1.103.

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The present paper deals with the study of the depositional environment and tectonic setting during the sedimentation of the Barail Group of rocks of the Indo-Myanmar Ranges (IMR). The Barail Group (Oligocene) consist of sandstone intercalated with shale and siltstone. Geochemical study suggests low to high degree of chemical weathering. ICV vs. CIA, Al2O3 vs. TiO2 diagrams indicate that the sediments were derived from the multiple source rocks dominantly of mafic composition. Arid to semi-arid/semi-humid climate prevailed during the deposition of the Barail Group sediments. Sedimentation occurred in a tectonic setting of overlap of passive to active continental margin under marine environment.

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Yamamuro, Jerry A., Fletcher M. Wood e Poul V. Lade. "Effect of depositional method on the microstructure of silty sand". Canadian Geotechnical Journal 45, n. 11 (novembre 2008): 1538–55. http://dx.doi.org/10.1139/t08-080.

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The results from a laboratory experimental study on silty sand are presented. A scanning electron microscope (SEM) was used to investigate the effect of depositional method and silt content on the grain contact structure of silty sand. Triaxial specimens containing Nevada sand with various quantities of nonplastic silt were isotropically consolidated to 25 kPa and then preserved through epoxy impregnation. Specimens were formed using both dry funnel deposition and water sedimentation. A procedure was developed that allowed the microstructure to be quantified in terms of potentially stable and unstable grain contacts. As silt content increased, the percentage of stable grain contacts decreased. Specimens formed by dry funnel deposition contained a higher percentage of potentially unstable grain contacts than those reconstituted by water sedimentation, possibly reflecting a more compressible particle structure. This effect became more pronounced as silt content increased. A description of the specimen preservation technique as well as the methodology used to both prepare and analyze SEM specimens for grain contact analysis are presented.

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19

Ali, Syed Haroon, Osman M. Abdullatif, Lamidi O. Babalola, Fawwaz M. Alkhaldi, Yasir Bashir, S. M. Talha Qadri e Ali Wahid. "Sedimentary facies, depositional environments and conceptual outcrop analogue (Dam Formation, early Miocene) Eastern Arabian Platform, Saudi Arabia: a new high-resolution approach". Journal of Petroleum Exploration and Production Technology 11, n. 6 (15 maggio 2021): 2497–518. http://dx.doi.org/10.1007/s13202-021-01181-7.

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AbstractThis paper presents the facies and depositional environment of the early Miocene Dam Formation, Eastern Arabian platform, Saudi Arabia. Deposition of Dam Formation (Fm.) was considered as a restricted shallow marine deposition. Few studies suggest the role of sea-level change in its deposition but were without decisive substantiation. Here, we describe the facies and high-resolution model of Dam Fm. under varying depositional conditions. The depositional conditions were subjected to changing relative sea level and tectonics. High-resolution outcrop photographs, sedimentological logs, and thin sections present that the mixed carbonate–siliciclastic sequence was affected by a regional tectonics. The lower part of Dam Fm. presents the development of carbonate ramp conditions that are represented by limestones and marl. The depositional conditions fluctuated with the fall of sea level, and uplift in the region pushed the siliciclastic down-dip and covered the whole platform. The subsequent rise in sea level was not as pronounced and thus allowed the deposition of microbial laminites and stromatolitic facies. The southeast outcrops, down-dip, are more carbonate prone as compared to the northwest outcrop, which allowed the deposition of siliciclastic-prone sedimentation up-dip. All facies, architecture, heterogeneity, and deposition were controlled by tectonic events including uplift, subsidence, tilting, and syn-sedimentary faulting, consequently affecting relative sea level. The resulting conceptual outcrop model would help to improve our understanding of mixed carbonate–siliciclastic systems and serve as an analogue for other stratigraphic units in the Arabian plate and region. Our results show that Dam Fm. can be a good target for exploration in the Northern Arabian Gulf.

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20

Tchoumatchenco, Platon, Marlena Yaneva, Elena Koleva-Rekalova, Kristalina Stoykova e Daria Ivanova. "Jurassic stratigraphy of the section Staro selo, Pernik District, Southwestern Bulgaria". Geologica Balcanica 35, n. 1-2 (30 giugno 2005): 39–61. http://dx.doi.org/10.52321/geolbalc.35.1-2.39.

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The onset of the Jurassic sedimentation in the region of Pernik (southwestern Bulgaria) is at the end of Bajocian with deposition of sandstones (Lyalintsi Member of Gradets Fm.) and continuing during the Bathonian with bioclastic limestones (Polaten Fm.). The section Staro selo is one of the most complete Jurassic sections in Southwest Bulgaria. It is studied from several points of view: lithofacial, depositional processes, biostratigraphic and sequence stratigraphic. In Bajocian-Bathonian interval four 3rd order depositional sequences are individualized: Bj 5, Bat 0, Bat 1 and Bat 2. After a break of sedimentation (Callovian-Oxfordian), the limestones of Gintsi (Lower Kimmeridgian) and Drugan (Middle Kimmeridgian) Formation were deposited in which 3 depositional sequences were recognized (Kim 2-Kim 4). Nineteen depositional sequences of 3rd order are individualized (Kim 5-Ti 1.1-Ti 1.13, Ti 2, Ti 3.1-Ti3.2, Ti 4, Ti 5) in the sediments of Neshkovtsi Formation (Upper Kimmeridgian) and in the Bobovo Member of Kostel Formation (Uppermost Kimmeridgian – Upper Tithonian in the studied area). The recognition of the depositional sequences is based chiefly on the geometry and the superposition of the calcareous and siliciclastic sediments. The divided depositional sequences are compared to those of Western European scheme of Hardenbol et al. (1998). Within the carbonate part of the succession they are of the same number and in the siliciclastic part they are more numerous.

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21

Fakhruddin, Rakhmat. "Fluvial-Tidal to Fluvial-Lacustrine Sedimentation of the Middle Miocene to Pleistocene Mapia Formation, Dogiyai, Papua (Indonesia)". Sains Malaysiana 50, n. 7 (31 luglio 2021): 1885–99. http://dx.doi.org/10.17576/jsm-2021-5007-05.

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A sedimentological and palynological investigation was carried out on outcropping sedimentary rocks at Dogiyai, Papua, proposed to be named as the Mapia Formation. The age range is from Middle Miocene to Pleistocene. The lower Mapia Formation was deposited at Metroxylon type to Nothofagus emarcida Zone, Middle Miocene to Early Pliocene. It is comprised of three facies associations: tidal channel, tidal point bar, and tidal flat deposits. A tidally dominated fluvially influenced depositional environment is suggested for the deposition of sediments of this unit. The upper Mapia Formation was deposited at Malvacipollis diversus Zone, Garcinia cuspidata type Zone, and Proteacidites sp. Zone, Late Pliocene to Pleistocene. It is comprised of five facies associations: delta front, slump, debrite, turbidite, and lacustrine mud deposits. A non-channelized deep-lacustrine slump and debris-flow dominated depositional environment is suggested for the deposition of sediments of this unit. The lower Mapia Formation was deposited as synorogenic clastic sediments at the beginning of Central Range orogeny event while the upper Mapia Formation was deposited in the piggyback basin at the major uplift event.

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22

Stovin, Virginia R., e Adrian J. Saul. "Sedimentation in Storage Tank Structures". Water Science and Technology 29, n. 1-2 (1 gennaio 1994): 363–72. http://dx.doi.org/10.2166/wst.1994.0684.

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Abstract (sommario):

Although storage tanks provide an effective means of reducing the magnitude and frequency of combined sewer overflow discharges, and thereby of alleviating urban watercourse pollution, poorly designed storage structures frequently suffer from maintenance problems arising from sedimentation. The development of design guidelines that optimise the self-cleansing operation of storage structures is clearly a priority for urban drainage research. This paper describes a system that has been developed to study sediment deposition in laboratory model-scale storage structures. The patterns of deposition resulting from a selection of flow regimes are described, and the need for time-varying and time series storm tests is highlighted. Sedimentation patterns are shown to predominantly depend on the flow field, and the critical bed shear stresses for deposition and erosion in the model situation are identified. Hence, the potential application of numerical models to the design problem is discussed.

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23

Vähäkuopus, Tuija, Tommi Kauppila, Jari Mäkinen, Antti E. K. Ojala e Samu E. Valpola. "Sedimentation Patterns of Multiple Finnish Lakes Reveal the Main Environmental Stressors and the Role of Peat Extraction in Lake Sedimentation". Geosciences 10, n. 8 (13 agosto 2020): 313. http://dx.doi.org/10.3390/geosciences10080313.

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Human land-use activities, especially in the peatlands, are under consideration as the mitigation and lowering of CO2 emissions from land-use practices is needed to address climate change. In Finland, approximately one third of the land surface is covered by peatlands, and around 50% of peatlands are ditched for forestry. Another 3% of peatlands are used for agriculture and approximately 1% for peat extraction. The effects of these different land-use practices, including changes in sediment depositional rates and sediment quality, need to be identified. This study analyzed 51 lakes that were subdivided into two groups: (1) a group of impacted lakes in which peat was recently extracted from the catchments and (2) a reference group consisting of lakes where peat had not been extracted from the basin, but in which other land-use activities had occurred. The overall aim of the study was to investigate if peat extraction caused excessive delivery and deposition of dry and organic matter in lakes that are located in their immediate downstream catchment areas. Differences in sediment accumulation were defined by comparing the overall sediment thickness and recent (post 1986) sedimentation levels to identify if there were differences in the sediment chemical composition or rate of organic matter deposition between groups and to identify possible land-use stressors that could explain the possible differences in sediment chemical assemblages or sedimentation rates. The results show moderate (cm scale) sedimentation rates in both impacted and reference lakes after 1986, while sediment chemical assemblages indicated the erosion and input of mineral soils to all of the studied lakes, rather than the input of organic materials. No statistically significant correlations were observed between selected environmental variables and the recent accumulation rates of carbon and dry matter. Moreover, significant changes in the stressors potentially affecting the chemical assemblages of pre- and post-disturbance sediments were not observed.

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24

Bonnas, Sylvia, Jan Tabellion e Jürgen Haußelt. "Effect of Particle Size Distribution and Sedimentation Behaviour on Electrophoretic Deposition of Ceramic Suspensions". Key Engineering Materials 314 (luglio 2006): 69–74. http://dx.doi.org/10.4028/www.scientific.net/kem.314.69.

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By systematic interaction of sedimentation and electrical field in electrophoretic deposition the particle size distribution of the deposited green body can be influenced. This can be employed for producing coatings with a very smooth surface by deposition of only the nanosized fraction of a conventional powder with broad or non-monomodal size distribution, thus avoiding preceding classification. In this paper, the preparation of stabilised slurries is described focussing on the criteria particle size distribution, zeta-potential and sedimentation behaviour. The effectiveness of the interaction of sedimentation and electrophoretic deposition is to be shown.

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25

Yang, Dongfang, Tao Jiang, Linzhen Wei, Shengjun Zhang e Xinmin Huang. "The Lowest Deposition of Hg Content is in the Jiaozhou Bay Center". E3S Web of Conferences 233 (2021): 03041. http://dx.doi.org/10.1051/e3sconf/202123303041.

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Based on the investigation data of Jiaozhou Bay in 1992, this thesis studied the present situation and horizontal distribution of Hg content in the bottom of Jiaozhou Bay mouth. The results showed that in May, August and October, the range of Hg content in the bottom ofJiaozhou Bay was 0.007-0.040 μg/L, which was in line with the national water quality standard for class I seawater. This showed that in terms of Hg content, the bottom water of Jiaozhou Bay from the center of the bay to the south of the bay mouth was not polluted by any Hg content in May, August and October. In the bottom of Jiaozhou Bay, in May, the range of Hg content in Jiaozhou Bay was 0.013-0.019 μg/L. In August, the range of Hg content in Jiaozhou Bay was 0.021-0.025 μg/L. In October, the range of Hg content in Jiaozhou Bay was 0.007-0.040 μg/L. Therefore, in May, August and October, the water of Jiaozhou Bay was not polluted by any Hg content. In May, a high sedimentation of Hg contentwas in the coastal waters of the eastern part of the Bay. In August, a high sedimentationof Hg content was in the coastal waters and the estuary waters in the east of the Bay. In October, a high sedimentation of Hg content was in the south of the bay mouth. However, from May to August, and then to October, the lowest Hg content sedimentationwas in the central waters of the Bay.

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26

Atar, Elizabeth, Andrew C. Aplin, Violaine Lamoureux-Var, Christian März e Thomas Wagner. "Sedimentation of the Kimmeridge Clay Formation in the Cleveland Basin (Yorkshire, UK)". Minerals 10, n. 11 (2 novembre 2020): 977. http://dx.doi.org/10.3390/min10110977.

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Fine-grained sedimentary successions contain the most detailed record of past environmental conditions. High-resolution analyses of these successions yield important insights into sedimentary composition and depositional processes and are, therefore, required to contextualise and interpret geochemical data which are commonly used as palaeoclimate proxies. The Kimmeridge Clay Formation (KCF) is a 500 m-thick mudstone succession deposited throughout the North Sea in the Late Jurassic and records environmental conditions through this time. Here, we present petrographic analyses (on 36 thin sections) on a 50 m section of a KCF core from the Cleveland Basin (Yorkshire, UK) to investigate controls on sedimentation in this region during the Tithonian, Late Jurassic. Facies descriptions demonstrate that deposition took place in a hydrodynamically variable environment in which the sediment origins, sediment dispersal mechanisms, and redox conditions fluctuated on the scale of thousands of years. Petrographic analyses show that the sediment comprises marine (algal macerals, calcareous fossils), detrital (quartz, clay, feldspar), and diagenetic (dolomite and authigenic kaolinite) components and that several sediment dispersal mechanisms influenced deposition and facilitated both the supply and preservation of terrestrial and marine organic material. This work provides a framework for the interpretation of geochemical palaeoclimate proxies and reinforces the importance of looking at the rock when interpreting whole-rock geochemical data.

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27

Kerkweg, A., J. Buchholz, L. Ganzeveld, A. Pozzer, H. Tost e P. Jöckel. "Technical Note: an implementation of the dry removal processes DRY DEPosition and SEDImentation in the Modular Earth Submodel System (MESSy)". Atmospheric Chemistry and Physics Discussions 6, n. 4 (24 luglio 2006): 6853–901. http://dx.doi.org/10.5194/acpd-6-6853-2006.

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Abstract. We present the submodels DRYDEP and SEDI for the Modular Earth Submodel System (MESSy). Gas phase and aerosol dry deposition are calculated within DRYDEP, whereas SEDI deals with aerosol particle sedimentation. Dry deposition velocities depend on the near-surface turbulence and the physical and chemical properties of the surface cover (e.g. the roughness length, soil pH or leaf stomatal exchange). The dry deposition algorithm used in DRYDEP is based on the big leaf approach and is described in detail within this Technical Note. The sedimentation submodel SEDI contains two sedimentation schemes: a simple upwind zeroth order scheme and a first order approach.

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28

Kerkweg, A., J. Buchholz, L. Ganzeveld, A. Pozzer, H. Tost e P. Jöckel. "Technical Note: An implementation of the dry removal processes DRY DEPosition and SEDImentation in the Modular Earth Submodel System (MESSy)". Atmospheric Chemistry and Physics 6, n. 12 (12 ottobre 2006): 4617–32. http://dx.doi.org/10.5194/acp-6-4617-2006.

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Abstract (sommario):

Abstract. We present the submodels DRYDEP and SEDI for the Modular Earth Submodel System (MESSy). Dry deposition of gases and aerosols is calculated within DRYDEP, whereas SEDI deals with aerosol particle sedimentation. Dry deposition velocities depend on the near-surface turbulence and the physical and chemical properties of the surface cover (e.g. the roughness length, soil pH or leaf stomatal exchange). The dry deposition algorithm used in DRYDEP is based on the big leaf approach and is described in detail within this Technical Note. The sedimentation submodel SEDI contains two sedimentation schemes: a simple upwind zeroth order scheme and a first order approach.

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29

Campos, Jody, Iran Eduardo Lima Neto, Ticiana Marinho Studart e José Nilson Beserra Campos. "Influence of sediment distribution on the relationships among reservoir yield, spill, and evaporation losses". Engenharia Sanitaria e Ambiental 23, n. 5 (ottobre 2018): 849–56. http://dx.doi.org/10.1590/s1413-41522018177058.

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ABSTRACT This study shows how the sedimentation process in reservoirs affects the yield-spill-evaporation losses in reservoirs of Ceará State, Brazilian Northeast. Reservoirs are assumed to have, initially, inverted conical shape. Three forms of sedimentation were investigated: type 1, with deposition occurring parallel to the wetted perimeter; type 2, deposition distributed proportionally to the water depth; and, type 3, deposition concentrated in the reservoir bottom. These sedimentation patterns were found in many reservoirs in Ceará, with capacity ranging from about 0.5 to 100 hm3. Nevertheless, type 2 pattern was the most frequent. In this paper, five large reservoirs, over 100 hm3, were studied using Monte Carlo approach, and considering the silting over the time horizon. It was found that sediment distribution can significantly affect the yield-spill-evaporation trade-off on large reservoirs. Type 1 results have the lowest impact on reservoir yield, followed by type 2 and type 3. For Cedro reservoir, the yield would go to zero in 2115, assuming a type 3 deposition pattern. These results reinforce the need for monitoring sedimentation in large reservoirs in the Brazilian semiarid region. In addition, this study provides a relatively simple methodology to predict the impact of siltation on reservoir yield-spill-evaporation relationships, for the three most found patterns of sedimentation.

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30

Orme, Devon A., e Kathleen D. Surpless. "The birth of a forearc: The basal Great Valley Group, California, USA". Geology 47, n. 8 (6 giugno 2019): 757–61. http://dx.doi.org/10.1130/g46283.1.

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AbstractThe Great Valley basin of California (USA) is an archetypal forearc basin, yet the timing, structural style, and location of basin development remain controversial. Eighteen of 20 detrital zircon samples (3711 new U-Pb ages) from basal strata of the Great Valley forearc basin contain Cretaceous grains, with nine samples yielding statistically robust Cretaceous maximum depositional ages (MDAs), two with MDAs that overlap the Jurassic-Cretaceous boundary, suggesting earliest Cretaceous deposition, and nine with Jurassic MDAs consistent with latest Jurassic deposition. In addition, the pre-Mesozoic age populations of our samples are consistent with central North America sources and do not require a southern provenance. We interpret that diachronous initiation of sedimentation reflects the growth of isolated depocenters, consistent with an extensional model for the early stages of forearc basin development.

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31

Kaszycki, Christine A. "A model for glacial and proglacial sedimentation in the shield terrane of southern Ontario". Canadian Journal of Earth Sciences 24, n. 12 (1 dicembre 1987): 2373–91. http://dx.doi.org/10.1139/e87-223.

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Zonal stagnation is an important element in the regional style of deglaciation in areas of moderate bedrock relief (50–150 m), such as the shield terrane of southern Ontario. Bedrock topography played a major role in the stagnation process, as ice blocks were trapped within bedrock basins of all sizes. Stagnation occurred subglacially as the ice sheet thinned and trapped basal ice became increasingly isolated from its source. Sediment–landform relationships support this model. Bedrock lakes are floored by highly faulted laminated sediment, often displaying large ice-block casts. The dominant depositional landforms are ice-contact terraces, which flank valley walls. Sediment forming the terraces is variable, depending upon ice-marginal depositional environment.Models for two depositional systems are developed: (1) localized ice-marginal and subglacial sedimentation in upland terrain, and (2) thick proglacial basin-fill sequences developed in major structural valleys. In upland areas, sediment cover is thin and discontinuous and is composed primarily of complex sediment-flow assemblages. Basal till is rare but occurs as two distinct lithofacies representing (1) meltout from beneath wholly stagnant ice, and (2) deposition by basal melting from thin slabs of stagnant, debris-rich ice lodged beneath an active shear zone. Thick proglacial basin-fill sequences exhibit complex facies relationships. Ice-contact lacustrine terraces comprise fining-upward subaqueous outwash sequences, developed as density underflows were funnelled between rock knobs and blocks of stagnant ice. Kettle lakes developed within large basins where ice blocks persisted for the longest period of time.

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Amijaya, Donatus Hendra, Najibatul Adibah e Ahmad Z. A. Ansory. "Lithofacies and Sedimentation of Organic Matter in Fine Grained Rocks of Nanggulan Formation in Kulon Progo, Yogyakarta". Journal of Applied Geology 1, n. 2 (26 luglio 2016): 82. http://dx.doi.org/10.22146/jag.26964.

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Abstract (sommario):

Fine grained rocks especially shale play a significant role in shale hydrocarbon system. Research on Eocene Nanggulan shale becomes an interest lately since this shale is considered as prospective interval for shale gas source. It potentially contains significant organic matter because coaly sediment is found in this formation as well. Nanggulan Formation fine grained rocks was deposited in various depositional environment from estuary – shallow marine. This paper integrates the result of lithofacies and depositional environment analysis with organic geochemical data to understand the sedimentation process of organic matter. Samples were taken from cores. The result of 14 geochemically analysed samples shows Total Organic Carbon (TOC) content between 0.36–1.00 % for fin e grained rocks (shales) and 12.80 % for coaly shales. Nine samples are categorized as fair and 2 samples are categorized as good source rock. The depositional environment of Nanggulan Formation sediment, which was shallow marine at Late Eocene and estuary (salt marsh) at Early Eocene, produced sediment with higher TOC. Whereas the deposition of sediment in estuary (tidal flat) at Middle Eocene produced lower content of TOC. Vulcanic activity at Middle Eocene also caused less organic material preservation because it produced abundant inorganic material.

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Ren, Zhihui, Ting Wang, Yuanjian Wang e Shaojun Qu. "A study on the characteristics and influencing factors of reservoir sedimentation in Wanjiazhai Reservoir". MATEC Web of Conferences 246 (2018): 01046. http://dx.doi.org/10.1051/matecconf/201824601046.

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Abstract (sommario):

Based on measured data of the Wanjiazhai Reservoir in different periods, the characteristics of the spatial and temporal distribution of sedimentation in the reservoir area were preliminarily analyzed and the impact of reservoir operation on this distribution was discussed. Primary conclusions are as followed: in terms of temporal distribution, sedimentation continuously accumulated over the period from 2000 to 2017, with the sediment deposition ratio dramatically decreasing between 2011 and 2017; in terms of spatial distribution, the sedimentation in the reservoir area was mainly concentrated downstream of the WD54 section, with the highest concentration being downstream of the WD23 section. The characteristics of sedimentation distribution in the reservoir area were closely related to inflow and sediment conditions and reservoir operation water level. When the water level was lower than 952 m, the sediment deposition ratio was lower than 0. To further improve the sediment deposition form in the reservoir area, lowering water level and ejecting the sediment are recommended in a timely manner.

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34

Cheadle, Burns A. "Alluvial–playa sedimentation in the lower Keweenawan Sibley Group, Thunder Bay District, Ontario". Canadian Journal of Earth Sciences 23, n. 4 (1 aprile 1986): 527–42. http://dx.doi.org/10.1139/e86-053.

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Abstract (sommario):

The Middle Proterozoic Sibley Group is a mixed clastic–carbonate red bed sequence located in the Thunder Bay – Nipigon area on the north shore of Lake Superior. The lowest unit, the Pass Lake Formation, consists of a basal paraconglomerate member, of probable alluvial debris-flow origin, overlain by 20–80 m of plane-bedded and cross-bedded quartz arenites, which were probably deposited by sheetfloods and eolian processes on alluvial outwash sand flats. The overlying Rossport Formation is dominated by red and buff dolomicritic mudstone. The association of these mudstones with relatively pure massive carbonate beds and sheetflood sandstone units is strongly suggestive of a playa lake depositional environment. Fluctuations in playa lake levels may have resulted in oscillations between carbonate-dominated and clastic-dominated sedimentation. The upper unit, the Kama Hill Formation, consists of horizontally laminated purple shales and ripple cross-laminated buff siltstones to fine sandstones. The presence of stacked "powering-down" sequences and abundant dessiccation features is suggestive of sheetflood deposition on a distal alluvial floodplain.The sequence of depositional environments suggests that the Sibley Basin formed by stretching and sagging of the Middle Proterozoic crust preceding the main period of volcanic activity along the Keweenawan Midcontinent Rift Zone. In this sense, the Sibley Group red beds represent the earliest products of Keweenawan rifting. They were not, however, deposited in a classical aulacogen or "failed arm."

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35

Pisarska-Jamroży, Małgorzata, Katarzyna Machowiak e Dariusz Krzyszkowski. "Sedimentation style of a Pleistocene kame terrace from the Western Sudety Mountains, S Poland". Geologos 16, n. 2 (1 giugno 2010): 101–10. http://dx.doi.org/10.2478/v10118-009-0008-8.

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Sedimentation style of a Pleistocene kame terrace from the Western Sudety Mountains, S PolandThe depositional conditions of kame terraces in a mountain valley were analysed sedimentologically and petrologically through a series of kame terraces in the Rudawy Janowickie mountains. The kame terraces comprise five lithofacies associations. Lithofacies association GRt, Sp originates from deposition in the high-energy, deep gravel-bed channel of a braided river. Lithofacies association GC represents a washed out glacial till. Probably a thin layer of till was washed out by sandy braided rivers (Sp). The fourth association (Fh, Fm) indicates a shallow and quite small glaciomarginal lake. The last association (GRt, GRp) indicates the return of deposition in a sandy-bed braided channel. The petrography of the Janowice Wiekie pit and measurements of cross-stratified beds indicate a palaeocurrent direction from N to S. The Janowice Wielkie sedimentary succession accumulated most probably during the Saalian (Odranian, Saale I, Drenthe) as the first phase of ice-sheet melting, because the kame terrace under study is the highest one, 25-27 m above the Bóbr river level. The deposits under study are dominated by local components. The proglacial streams flowed along the margin of the ice sheet and deposited the kame terrace. The majority of the sedimentary succession was deposited in a confined braided-river system in quite deep channels.

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36

Griffiths, C. M., e E. Paraschivoiu. "THREE-DIMENSIONAL FORWARD STRATIGRAPHIC MODELLING OF EARLY CRETACEOUS SEDIMENTATION ON THE LEVEQUE AND YAMPI SHELVES, BROWSE BASIN". APPEA Journal 38, n. 1 (1998): 147. http://dx.doi.org/10.1071/aj97008.

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Abstract (sommario):

Early Cretaceous clastic sedimentation on the Leveque and Yampi Shelf areas of the Browse Basin has been brought sharply into focus recently as a result of exploration success at Gwydion and Cornea. The changing nature of clastic sedimentation patterns in the shallow-to-deep marine environments during C. delicata to upper S. areolata times is of increasing exploration interest. This study was designed to address the following questions: Could the conceptual geological model discussed by Spry and Ward (1997) generate potential reservoir sands in the region from Leveque-1 to Yampi-1?What would be the geometry and depositional environment of such sands?SEDSIM is a three-dimensional stratigraphic forward modelling program developed at Stanford University. The program models sediment erosion, transport, and deposition, and predicts clastic sediment distribution on a given bathymetric surface. SEDSIM was used to simulate one million years of deposition on the Leveque and Yampi Shelves from approximately 145 Ma. The model illustrates the use of 3D stratigraphic forward modelling in illustrating and testing stratigraphic play fairway concepts and the development of sedimentation patterns. Reprocessed seismic data from Seismic Australia were used together with a depth-converted near Base Cretaceous surface provided by Woodside Offshore Petroleum. Input data include; a high resolution relative sea-level curve, an understanding of wind and wave directions throughout the modelled period, tectonic movements throughout the modelled area, the nature of the underlying strata, sediment input points, and grain-size distributions. The simulation clearly shows the development of linear shelfal sands on the C. delicata flooding surface during the following regression. Further work will extend the study to early M. australis times.

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37

Stollhofen, Harald. "Karoo synrift-deposition and its tectonic control at the evolving continental margin of Namibia". Zeitschrift der Deutschen Geologischen Gesellschaft 149, n. 4 (19 marzo 1999): 519–632. http://dx.doi.org/10.1127/zdgg/149/1999/519.

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38

Miguez-Salas, Olmo, e Francisco J. RodrÍguez-Tovar. "Ichnofabric analysis as a tool for characterization and differentiation between calcareous contourites and calciturbidites". Journal of Sedimentary Research 91, n. 11 (12 novembre 2021): 1151–65. http://dx.doi.org/10.2110/jsr.2020.147.

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ABSTRACT The Eocene–Miocene Cyprus paleoslope system records complex deep-marine sedimentation comprising background vertical settling of autochthonous pelagic–hemipelagic particles (chalks) which were punctuated by calcareous bottom currents (contourites) and gravity flows (calciturbidites). The Eocene Lefkara Formation at the Petra Tou Romiou beach section (Cyprus) shows the incidence of deep-marine bottom currents and distal turbiditic episodes in a context of pelagic–hemipelagic sedimentation. Trace-fossil analysis of this section, using an ichnofabric approach (i.e., ichnodiversity, Bioturbation Index, Bedding Plane Horizontal Index and crosscutting relationships), was conducted to precisely describe the paleoenvironmental conditions of this complex setting. Ichnofabric analysis allow the characterization and differentiation of sporadic turbiditic events that disrupted both pelagic–hemipelagic and contourite deposition. Calciturbidite intervals show ichnofabrics consisting of postdepositional U-shaped traces (i.e., Arenicolites isp., ?Diplocraterion isp.,) and vertical borings typical of consolidated substrates. High-energy sandy contourite deposits are dominated by horizontal deposit-feeder traces and the development of ichnofabrics with Planolites isp., and Thalassinoides isp. The record of ichnofabrics with slightly deformed Planolites in the interbeds of sandy contourites or in the transition between the facies reveals variations in sedimentation in the bi-gradational contourite succession, and can potentially act as an indicator of depositional hiatus.

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Walley, C. D. "Depositional history of southern Tunisia and northwestern Libya in Mid and Late Jurassic time". Geological Magazine 122, n. 3 (maggio 1985): 233–47. http://dx.doi.org/10.1017/s0016756800031447.

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AbstractThe good exposures of virtually undeformed Callovian and Oxfordian strata along the Djeffara escarpment of southern Tunisia and northwestern Libya have allowed analysis of regional depositional history during this time.A number of lithostratigraphic problems are considered. In Tunisia, the Foum Tatahouine Formation is subdivided into members and in Libya some of the stratigraphic issues are clarified. A correlation between the two sequences is proposed. The widely claimed aeolian origin for the Libyan Chameau Mort Sandstone is rejected.The depositional patterns of the Callovian and Oxfordian strata are described in the context of Mid and Late Jurassic sedimentation in the eastern Ghadames basin of the African craton. After a regressive Bathonian sequence, transgressive conditions commenced in Early Callovian time. In a series of continental–marine cycles, this transgressive sequence culminated in widespread shallow, restricted-marine micritic deposition. A regression in Late Callovian time resulted in emergence marked by a thin but widespread calcrete horizon. In Mid? Oxfordian time a renewed transgression brought in open marine, high-energy, shallow-water carbonates. Later, regressive conditions returned, leading to increasing restriction, and latest Jurassic time saw the first signs of the fluvio-deltaic deposition that was to dominate the region in Early Cretaceous time.

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Markova, Irina, e Yuliya Bryanskaya. "Restrained fall velocity of suspended solids particles sedimentation in still water". E3S Web of Conferences 91 (2019): 07004. http://dx.doi.org/10.1051/e3sconf/20199107004.

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The deposition rate is sufficiently studied in the case of single particles or in conditions of low concentrations of suspended matter, in which the precipitating particles do not affect each other. In the article, the method of calculation of the rate of the constrained deposition is offered, comparative calculations of the rate of the free and constrained deposition of particles are executed, the settlement results reflecting essential difference of the speed of the constrained and free deposition of particles are presented. The factors influencing the rate of confined deposition, among which the main one is the concentration of suspended matter in water, are considered. The experimental data confirming the reduction of speed of the constrained deposition of more than 3 times in a five-fold increase in the concentration of suspended solids is given. The dependence of the strained deposition rate of particles on the concentration of the suspension is obtained.

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Dietze, E., F. Maussion, M. Ahlborn, B. Diekmann, K. Hartmann, K. Henkel, T. Kasper, G. Lockot, S. Opitz e T. Haberzettl. "Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments". Climate of the Past 10, n. 1 (16 gennaio 2014): 91–106. http://dx.doi.org/10.5194/cp-10-91-2014.

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Abstract. Grain-size distributions offer powerful proxies of past environmental conditions that are related to sediment sorting processes. However, they are often of multimodal character because sediments can get mixed during deposition. To facilitate the use of grain size as palaeoenvironmental proxy, this study aims to distinguish the main detrital processes that contribute to lacustrine sedimentation across the Tibetan Plateau using grain-size end-member modelling analysis. Between three and five robust grain-size end-member subpopulations were distinguished at different sites from similarly–likely end-member model runs. Their main modes were grouped and linked to common sediment transport and depositional processes that can be associated with contemporary Tibetan climate (precipitation patterns and lake ice phenology, gridded wind and shear stress data from the High Asia Reanalysis) and local catchment configurations. The coarse sands and clays with grain-size modes >250 μm and <2 μm were probably transported by fluvial processes. Aeolian sands (~200 μm) and coarse local dust (~60 μm), transported by saltation and in near-surface suspension clouds, are probably related to occasional westerly storms in winter and spring. Coarse regional dust with modes ~25 μm may derive from near-by sources that keep in longer term suspension. The continuous background dust is differentiated into two robust end members (modes: 5–10 and 2–5 μm) that may represent different sources, wind directions and/or sediment trapping dynamics from long-range, upper-level westerly and episodic northerly wind transport. According to this study grain-size end members of only fluvial origin contribute small amounts to mean Tibetan lake sedimentation (19± 5%), whereas local to regional aeolian transport and background dust deposition dominate the clastic sedimentation in Tibetan lakes (contributions: 42 ± 14% and 51 ± 11%). However, fluvial and alluvial reworking of aeolian material from nearby slopes during summer seems to limit end-member interpretation and should be crosschecked with other proxy information. If not considered as a stand-alone proxy, a high transferability to other regions and sediment archives allows helpful reconstructions of past sedimentation history.

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42

Dietze, E., F. Maussion, M. Ahlborn, B. Diekmann, K. Hartmann, K. Henkel, T. Kasper, G. Lockot, S. Opitz e T. Haberzettl. "Sediment transport processes across the Tibetan Plateau inferred from robust grain size end-members in lake sediments". Climate of the Past Discussions 9, n. 4 (21 agosto 2013): 4855–92. http://dx.doi.org/10.5194/cpd-9-4855-2013.

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Abstract. Grain size distributions offer powerful proxies of past environmental conditions that are related to sediment sorting processes. However, they are often of multimodal character because sediments can get mixed during deposition. To facilitate the use of grain size as palaeoenvironmental proxy this study aims to distinguish the main detrital processes that contribute to lacustrine sedimentation across the Tibetan Plateau using grain size end-member modelling analysis. Between three and five robust grain size end-member subpopulations were distinguished at different sites from similarly-likely end-member model runs. Their main modes were grouped and linked to sediment transport and depositional processes associated with certain climatic background and catchment configurations. The coarse sands and clays with grain size modes > 250 μm and < 2 μm were probably transported by fluvial processes. Aeolian sands (~ 200 μm) and coarse local dust (~ 60 μm), transported by saltation and in near-surface suspension clouds, are probably related to occasional westerly storms in winter and spring. Coarse regional dust with modes ~ 25 μm may derive from near-by sources that keep in longer-term suspension. The continuous background dust is differentiated into two robust end-members (modes: 5–10 and 2–5 μm) that may represent different sources, wind directions and/or sediment trapping dynamics from long-range, upper-level westerly and episodic northerly wind transport. According to this study grain size end-members of only fluvial origin contribute small amounts to mean Tibetan lake sedimentation (19 ± 5%), whereas local to regional aeolian transport and background dust deposition dominate the clastic sedimentation in Tibetan lakes (contributions: 42 ± 14% and 51 ± 11%). However, fluvial and alluvial reworking of aeolian material from nearby slopes during summer seems to limit end-member interpretation and should be crosschecked with other proxy information. If not considered as a stand-alone proxy, a high transferability to other regions and sediment archives allows helpful reconstructions of past sedimentation history.

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Ismayilova, F. B. "Formation of sedimentation in oil mixing". Azerbaijan Oil Industry, n. 12 (15 dicembre 2020): 36–38. http://dx.doi.org/10.37474/0365-8554/2020-12-36-38.

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As a result of the studies on the impact of the mixing of various sorts of Azerbaijani oils on their quality parameters, it was defined that in some correlations oil mixing is impossible as both rheological and physico-chemical parameters of these oils after mixing abnormally change. In the context of the oils from Bulla and Garachukhur fields it was specified that in 58:42 ratio percentage correspondingly, abnormal phenomenon is observed in parameter change. Moreover, various ballast deposition occurs due to the mixing. The paper studies the kinetics of deposition of different ballasts (resin, asphaltene and paraffins, as well as water, salt and mechanical impurities) in the mixture of incompatible oils. It was defined that the main mass of all ballasts is deposited during 8–10 hours. The studies justified that depending on the chemical composition of the oils, the incompatibility in the mixture may also be occured in intensive seperation of various ballasts.

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Feng, Xiao Xiang, Zhe Liu e Xing Kui Wang. "Application Comparison about Sediment Deposition in Outer Channel by Three-Layer Mode and Analog Analysis Mode". Applied Mechanics and Materials 130-134 (ottobre 2011): 1638–44. http://dx.doi.org/10.4028/www.scientific.net/amm.130-134.1638.

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Sudden sedimentation is an important subject for building ports in silt-sandy coast. It elaborates calculation methods detailed about three-layer deposition mode and analogy analysis mode. And they are used to predict the deposition in outer channel of Binzhou Port. Comparative results show that they are basically same on the distribution of sudden sedimentation, deposition thickness and volume along the channel. And it is larger from three-layer deposition mode than analogy analysis mode. The formal mode is propitious to project security. By analyzing the characteristics and applicability about two methods, basic law is obtained for sediment movement and predicting methods under strong wind in the outer channel of silt-sandy coast.

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Riggs, N. R., T. B. Sanchez e S. J. Reynolds. "Evolution of the early Mesozoic Cordilleran arc: The detrital zircon record of back-arc basin deposits, Triassic Buckskin Formation, western Arizona and southeastern California, USA". Geosphere 16, n. 4 (30 giugno 2020): 1042–57. http://dx.doi.org/10.1130/ges02193.1.

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Abstract A shift in the depositional systems and tectonic regime along the western margin of Laurentia marked the end of the Paleozoic Era. The record of this transition and the inception and tectonic development of the Permo-Triassic Cordilleran magmatic arc is preserved in plutonic rocks in southwestern North America, in successions in the distal back-arc region on the Colorado Plateau, and in the more proximal back-arc region in the rocks of the Buckskin Formation of southeastern California and west-central Arizona (southwestern North America). The Buckskin Formation is correlated to the Lower–Middle Triassic Moenkopi and Upper Triassic Chinle Formations of the Colorado Plateau based on stratigraphic facies and position and new detrital zircon data. Calcareous, fine- to medium-grained and locally gypsiferous quartzites (quartz siltstone) of the lower and quartzite members of the Buckskin Formation were deposited in a marginal-marine environment between ca. 250 and 245 Ma, based on detrital zircon U-Pb data analysis, matching a detrital-zircon maximum depositional age of 250 Ma from the Holbrook Member of the Moenkopi Formation. An unconformity that separates the quartzite and phyllite members is inferred to be the Tr-3 unconformity that is documented across the Colorado Plateau, and marks a transition in depositional environments. Rocks of the phyllite and upper members were deposited in wholly continental depositional environments beginning at ca. 220 Ma. Lenticular bodies of pebble to cobble (meta) conglomerate and medium- to coarse-grained phyllite (subfeldspathic or quartz wacke) in the phyllite member indicate deposition in fluvial systems, whereas the fine- to medium-grained beds of quartzite (quartz arenite) in the upper member indicate deposition in fluvial and shallow-lacustrine environments. The lower and phyllite members show very strong age and Th/U overlap with grains derived from Cordilleran arc plutons. A normalized-distribution plot of Triassic ages across southwestern North America shows peak magmatism at ca. 260–250 Ma and 230–210 Ma, with relatively less activity at ca. 240 Ma, when a land bridge between the arc and the continent was established. Ages and facies of the Buckskin Formation provide insight into the tectono-magmatic evolution of early Mesozoic southwestern North America. During deposition of the lower and quartzite members, the Cordilleran arc was offshore and likely dominantly marine. Sedimentation patterns were most strongly influenced by the Sonoma orogeny in northern Nevada and Utah (USA). The Tr-3 unconformity corresponds to both a lull in magmatism and the “shoaling” of the arc. The phyllite and upper members were deposited in a sedimentary system that was still influenced by a strong contribution of detritus from headwaters far to the southeast, but more locally by a developing arc that had a far stronger effect on sedimentation than the initial phases of magmatism during deposition of the basal members.

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Koster, Kay, Jan Stafleu, Peter C. Vos e Michiel J. van der Meulen. "Can we elevate the subsiding coastal plain of the Netherlands with controlled sedimentation?" Proceedings of the International Association of Hydrological Sciences 382 (22 aprile 2020): 767–73. http://dx.doi.org/10.5194/piahs-382-767-2020.

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Abstract. Half the surface area of the coastal plain of the Netherlands has been subsiding below mean sea-level as a result of peatland drainage. At present, the low elevation is sustained, because sedimentation necessary to aggrade the coastal plain back to natural elevations is hampered by engineering structures. Alternatively, controlled sedimentation is a discussed method to elevate the coastal plain. This can either be achieved by allowing water courses to deliver sediments to designated areas, or by anthropogenic deposition. Here, we assess the possibilities of this strategy by determining whether natural systems or anthropogenic deposition are sufficient to elevate the surface to mean high water (MHW), taking into account IPCC projected minimum and maximum forecasted sea-level rise (RCP2.6 and RCP8.5), and predicted future subsidence. We use the 3D geological subsurface model GeoTOP to quantify sediments; i.e. clay and sand that were naturally delivered to the coastal plain by series of tidal inlets and the Rhine river system. Furthermore, we quantify the amount of anthropogenic deposition, and analyze documented supplies. Finally, we discuss the implications of controlled sedimentation in designated areas by providing examples of past embankment breaches. We quantify that 16.98 km3 of sediments are required to elevate the surface to MHW, and between 22.41 and 29.29 km3 at the end of the 21st century. We estimate that 45.30 km3 of sediments were delivered by the tidal systems during 3000 years (52 % sand), 20.18 km3 by the Rhine river system during 8000 years (29 % sand), and 3.59 km3 of anthropogenic deposition. We conclude that the coastal plain of the Netherlands cannot be elevated to more safe levels with controlled sedimentation. Exceptions are areas proximal to tidal systems with high sediment yields. Anthropogenic deposition, combining natural sedimentation with supplied sediments, or allowing peat growth in inundated areas could be viable alternatives as well as.

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Haque, Md Masidul, e Mrinal Kanti Roy. "Geology and sedimentary environment of the Surma Group of rocks, Bandarban anticline, Bandarban, Bangladesh". Journal of Nepal Geological Society 62 (14 settembre 2021): 88–106. http://dx.doi.org/10.3126/jngs.v62i0.38697.

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The study illustrates the effect of tectonics, climate, and relative sea-level change on the depositional process of the Miocene Bhuban and Boka Bil Formation of Bengal Basin. Outcrop sediments of five transverse sections exposed along the axial zone of Bandarban anticline were studied. Twelve lithofacies such as Gm, Gms, Sm, ST, Sp, Sr, Sl, Sf, Sll, Fw, Fl and Fm have been identified within the successions and grouped into (i) turbidite generated, (ii) outer fan distal lobe basin plain and (iii) tide-influenced facies association. The analyses reveal that the Bhuban Formation was turbidite- generated that deposited below the continental shelf-slope environment. The Lower Bhuban Member consists of gray to brownish-gray calcareous sandstone with shale deposited under the channelized lobe of submarine fan. The Middle Bhuban Member dominated by black shale-siltstone deposited in distal turbidite lobe due to change the flow regime. The Upper Bhuban Member consists of yellow to yellowish gray, coarse to medium-grained sandstone-siltstone with black shale that deposited under channelized to nonchannelized lobes of submarine fan. The increasing sedimentation during the formation of the Upper Bhuban Member can be caused by increased the intensity of the Asian Monsoon that carried huge sediment from the Himalaya. The Boka Bil Formation was deposited under estuary to tidal flat environment. The area was uplifted during and/or after subduction of the Indian Plate beneath the Burmese Plate. The monsoonal intensity enhances sedimentation that moved prograding delta towards the south. These processes shifted depositional environment from continental shelf-slope to marginal shallow marine during deposition of the Boka Bil Formation. The continental slope aligned east-west direction and sediments likely derived from the Himalaya and Trans-Himalaya in the present geographical setup during deposition of the sediments.

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Eltijani, Abdelrhim, Dávid Molnár, László Makó, János Geiger e Pál Sümegi. "Application of Parameterized Grain-Size Endmember Modeling in the Study of Quaternary Oxbow Lake Sedimentation: A Case Study of Tövises Bed Sediments in the Eastern Great Hungarian Plain". Quaternary 5, n. 4 (25 ottobre 2022): 44. http://dx.doi.org/10.3390/quat5040044.

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Abandoned channels are essential in the Quaternary floodplains, and their infill contains different paleoenvironment recorders. Grain-size distribution (GSD) is one proxy that helps characterize the alluviation and associated sedimentological processes of the abandoned channels. The classic statistical methods of the grain-size analysis provide insufficient information on the whole distribution; this necessitates a more comprehensive approach. Grain-size endmember modeling (EMM) is one approach beyond the traditional procedures that helps unmix the GSDs. This study describes the changes in the depositional process by unmixing the GSDs of a Holocene abandoned channel through parameterized EMM integrated with lithofacies, age–depth model, loss-on-ignition (LOI), and magnetic susceptibility (MS). This approach effectively enabled the quantification and characterization of up to four endmembers (EM1-4); the characteristics of grain-size endmembers imply changes in sedimentary environments since 8000 BP. EM1 is mainly clay and very fine silt, representing the fine component of the distribution corresponding to the background of quiet water sedimentation of the lacustrine phase. EM2 and EM3 are the intermediate components representing the distal overbank deposits of the flood. EM4 is dominated by coarse silt and very fine sand, representing deposition of overbank flow during the flood periods. This paper demonstrates that the parametrized grain-size EMM is reasonable in characterizing abandoned channel infill sedimentary depositional and sedimentation history.

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Pavlenko, Ivan, Marek Ochowiak, Praveen Agarwal, Radosław Olszewski, Bernard Michałek e Andżelika Krupińska. "Improvement of Mathematical Model for Sedimentation Process". Energies 14, n. 15 (28 luglio 2021): 4561. http://dx.doi.org/10.3390/en14154561.

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In this article, the fractional-order differential equation of particle sedimentation was obtained. It considers the Basset force’s fractional origin and contains the Riemann–Liouville fractional integral rewritten as a Grunwald–Letnikov derivative. As a result, the general solution of the proposed fractional-order differential equation was found analytically. The belonging of this solution to the real range of values was strictly theoretically proven. The obtained solution was validated on a particular analytical case study. In addition, it was proven numerically with the approach based on the S-approximation method using the block-pulse operational matrix. The proposed mathematical model can be applied for modeling the processes of fine particles sedimentation in liquids, aerosol deposition in gas flows, and particle deposition in gas-dispersed systems.

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Dashtgard, Shahin E., Ludvig Löwemark, Pei-Ling Wang, Romy A. Setiaji e Romain Vaucher. "Geochemical evidence of tropical cyclone controls on shallow-marine sedimentation (Pliocene, Taiwan)". Geology 49, n. 5 (26 gennaio 2021): 566–70. http://dx.doi.org/10.1130/g48586.1.

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Abstract Shallow-marine sediment typically contains a mix of marine and terrestrial organic material (OM). Most terrestrial OM enters the ocean through rivers, and marine OM is incorporated into the sediment through both suspension settling of marine plankton and sediment reworking by tides and waves under fair-weather conditions. River-derived terrestrial OM is delivered year-round, although sediment and OM delivery from rivers is typically highest during extreme weather events that impact river catchments. In Taiwan, tropical cyclones (TCs) are the dominant extreme weather event, and 75% of all sediment delivered to the surrounding ocean occurs during TCs. Distinguishing between sediment deposited during TCs and that redistributed by tides and waves during fair-weather conditions can be approximated using δ13Corg values and C:N ratios of OM. Lower Pliocene shallow-marine sedimentary strata in the Western Foreland Basin of Taiwan rarely exhibit physical evidence of storm-dominated deposition. Instead they comprise completely bioturbated intervals that transition upward into strata dominated by tidally generated sedimentary structures, indicating extensive sediment reworking under fair-weather conditions. However, these strata contain OM that is effectively 100% terrestrial OM in sediment that accumulated in estimated water depths <35 m. The overwhelming contribution of terrestrially sourced OM is attributed to the dominance of TCs on sedimentation, whereby ∼600,000 TCs are estimated to have impacted Taiwan during accumulation of the succession. In contrast, the virtual absence of marine OM indicates that organic contributions from suspension settling of marine OM is negligible regardless of the preserved evidence of extensive reworking under fair-weather conditions. These data suggest that (1) even in the absence of physical expressions of storm deposition, TCs still completely dominate sedimentation in shallow-marine environments, and (2) the organic geochemical signal of preserved shallow-marine strata is not reflective of day-to-day depositional conditions in the environment.

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