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1
Nordt, Lee. "Late quaternary alluvial stratigraphy of a low-order tributary in central texas, USA and its response to climate and sediment supply." Quaternary Research 62, no. 3 (November 2004): 289–300. http://dx.doi.org/10.1016/j.yqres.2004.07.004.
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This paper presents the first comprehensive late Quaternary alluvial stratigraphic study of a low-order tributary in central Texas, using Cowhouse Creek as a case study. The late Pleistocene Jackson (JA) alluvium forms the elevated T2 terrace. The entrenched Holocene valley is filled with the buried Georgetown (GT) alluvium (approximately 11,000 to 8000 14C yr B.P.) and associated Royalty paleosol, and the surficially exposed Fort Hood (FH) alluvium (approximately 7000 to 5000 14C yr B.P.) and West Range (WR) alluvium (approximately 4200 to 600 14C yr B.P.) forming the broad T1 terrace. The Ford (FO) alluvium (<600 14C yr B.P.) forms the modern T0 floodplain entrenched into T1. Conditioned by cooler and wetter climates, Cowhouse Creek was characterized by relatively high base flow and low sediment supply during deposition of the JA and GT alluvium. Appreciable upland soil erosion ensued during the middle Holocene in response to warmer climate conditions, resulting in widespread valley filling by the FH alluvium. Deposition of the late Holocene WR and F0 alluvium was characterized by diminished sediment storage during relatively stable climate conditions. The temporal alluvial stratigraphic framework of the bedrock-confined Cowhouse Creek valley is out of phase with the alluvial sequence in the larger Brazos River valley.
2
Liang, Jian Wen, and Ming Liang Liu. "Nonlinear Amplification of Seismic Ground Motion by Alluvial Valley." Applied Mechanics and Materials 438-439 (October 2013): 1572–76. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.1572.
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This paper studies nonlinear amplification of seismic ground motion by alluvial valley in layered sites. The equivalent linear method is used in dynamic analysis and transmitting boundaries are added at boundaries of the computation region. It is shown that, soil nonlinearity has significant effect on seismic ground motion around alluvial valley. The amplitudes in the case of linear alluvium and soil layers are the largest, those in the case of nonlinear alluvium and soil layers are the smallest, and those in the case of nonlinear alluvium and linear soil layers fall in between. The periods in the case of nonlinear alluvium and soil layers are the longest, those in the case of nonlinear alluvium and soil layers and those in the case of linear alluvium and linear soil layers are almost the same.
3
Waag, C. J., and T. G. Lane. "The Borah Peak, Idaho Earthquake of October 28, 1983—Structural Control of Groundwater Eruptions and Sediment Boil Formation in the Chilly Buttes Area." Earthquake Spectra 2, no. 1 (November 1985): 151–68. http://dx.doi.org/10.1193/1.1585306.
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Groundwater eruptions attendant to the Borah Peak earthquake formed more than 40 sediment boils. The eruptions were strongly controlled by solution widened fractures in limestone underlying alluvium. The dominant fracture set oriented N15°-20°W is imprinted upon the thin alluvial cover which is a confining layer. The fractures and shear zones in the alluvium served as important conduits for the discharge of groundwater. Water and air expulsed from the underlying carbonate entered the alluvium under high pressure and entrained and fluidized the alluvium forming sediment eruptions. The pressure surge which caused the eruptions probably resulted from a porewater pressure increase caused by compression of the carbonate in the hanging wall as it dropped.
4
Yatsyshyn, Andriy, and Andriy Bogucki. "Lithological characteristic of the riverbed alluvium of the sixth terrace of the Dnister–Stryvihor in the Dubrivka section (Forecarpathians)." Visnyk of the Lviv University. Series Geography, no. 49 (December 30, 2015): 348–63. http://dx.doi.org/10.30970/vgg.2015.49.8656.
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The main lithological characteristics of riverbed facies of alluvium of the sixth terrace above the floodplain of the Dnister-Stryvihor Rivers (Loyeva level) near Sambir were analysed. The granulometric and petrographic composition of the gravelly-pebble material, its roundness, form and the orientation of grains were characterised. Lithological analyses helped to determine that investigated layer of alluvium are poorly sorted. The three main components of alluvial strata (pebbles, gravel and sand-loamy filler) are present in approximately comparable proportions. Boulders are least common in the composition the alluvium. Coarse material is preferably well and medium rounded. Poorly and very well rounded fragments happen considerably rarely. The preferred direction of transport of fragment materials was Northwest–Southeast. Its direction is approximate to the current of modern Stryvihor. The fragments of the Carpathian rocks (sandstones, siltstones and silicates) dominate in a petrographic composition of coarse-grained alluvial deposits. That means that the Carpathians were the main source of supply of clastic material during the formation of investigated strata of alluvium. The rocks of local origin, which is involved from the bed of alluvium during the cutting of paleoStryvihor in the thickness of pre-Quaternary rocks of the Carpathian Foredeep, were mixed with the fragments of the Carpathian rocks in small amounts. The results of lithological studies show that paleo-Stryvihor accumulated the alluvial strata of Dubrivka section after that time when it had cut into the socle of Torhanovychi terrace up to 8–10 m before the deposition of alluvium. In other words, the preserved fragment of Loyeva level between the villages Torhanovychi and Dubrivka that is on the Dnister-Stryvihor interfluves consists of two terraces of different ages. One of them is a hypsometric higher and older Torhanovychi terrace, which was formed by paleo-Dnister River, and the other one is a hypsometric lower and respectively younger Dubrivka terrace, which was formed by paleo-Stryvihor River. Key words: alluvium, granulometric composition, petrographic composition, roundness of grains, sandstones, siltstones, silicates, gaizes, current of palaeochannel, Loyeva level.
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Husna, Abdullah, Rizka Akmalia, Faizal Immaddudin Wira Rohmat, Fauzan Ikhlas Wira Rohmat, Dede Rohmat, Winda Wijayasari, Pascalia Vinca Alvando, and Arif Wijaya. "Groundwater Sustainability Assessment against the Population Growth Modelling in Bima City, Indonesia." Water 15, no. 24 (December 13, 2023): 4262. http://dx.doi.org/10.3390/w15244262.
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Most of Indonesia’s population lives in areas with volcanic–alluvium geological characteristics. Based on the national hydrogeological map of the Indonesian Geological Agency, areas with volcanic–alluvium geological conditions have high groundwater potential and potential for groundwater damage. This study aims to test the resilience of groundwater areas with volcanic–alluvial characteristics to population growth. The MODFLOW groundwater model was built based on the site’s volcanic and alluvial geological conditions. This groundwater model was tested against pumping scenarios based on population water demand in 2011–2020 and then predicted population growth until 2030. The result shows that groundwater resilience in volcanic–alluvium locations has different characteristics based on lithology and population density characteristics. Urban areas that are mostly located in alluvium areas tend to have a linear groundwater decline pattern but have the sharpest groundwater decline gradient. In contrast, suburban areas in the alluvium-to-volcanic transition area initially experience exponential groundwater decline but change to linear, while rural areas located in volcanic areas that become the main development target have exponential groundwater decline characteristics. To counteract the continuous depletion of groundwater, researchers conducted a scenario for optimizing surface water use. Based on the results of the scenario, a 60% reduction in groundwater use is sufficient to stop continuous groundwater depletion. The results of this study can be used as a recommendation for long-term water resources management targets for volcanic and alluvium areas that are being targeted for development.
6
Yatsyshyn, Andriy, Andriy Bogucki, Danuta Olszewska-Nejbert, and Maciej Bąbel. "Palaeogeographical conditions of the formation of the channel alluvium of the high (Susidovychi) terrace of the Dnister River in the Kulakivtsi section (Podillia-Dnister region)." Visnyk of the Lviv University. Series Geography, no. 52 (June 27, 2018): 303–23. http://dx.doi.org/10.30970/vgg.2018.52.10196.
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The main lithological characteristics of the channel facies of the Susidovychi terrace, which correspond to the high (situated over the canyon) groups of Dnister terraces, were given. The investigations in the gravel pit at Kulakivtsi proved that the alluvium of the terrace has been formed in two stages. During the first stage, the lower 1.5 thick bed of the alluvium was deposited. The upper one, nearly 4 m thick alluvium bed was formed in the next, second one depositional stage. The stages of the alluvium formation were recorded in the changes of the granulometric and petrographical composition of the alluvium, and of the roundness of the coarse-grained clasts. The transition between these two alluvial beds is outlined by the voluminous intercalations of the sand lenses, and also by a change in the colour of the alluvial deposits. Granulometric composition of the alluvium of the channel facies, in general, changes little in the section. Only in the transition zone from the lower to the upper part of the alluvial deposits, there is a sharp, abrupt increase in the content of gravels and a sharp reduction in the content of boulders. Generally, in the composition of the alluvium two dominant and two subordinate components are clearly identified. The pebble grains and the sandy-clay matrix are the dominant components, whereas the gravel grains and the boulders are less common. Petrographic composition of the coarse-grained fraction of the terrace alluvium proved to be the richest of all the so far investigated sections of the high (situated over the canyon) terraces of the Dnister River (at Kunysivtsi, Ivane-Puste, Repuzhyntsi, and Lysychnyky). The pebbles 40–100 mm in diameter show particularly diverse petrographic composition which includes fragments of nine types of rocks: the four of the Carpathian provenance (sandstone, aleurite, cherts, and quartzite), and the five of the Podillian provenance (red-coloured Devonian sandstone, Albian cherts and sandstone, and lithothamnian and cryptocrystalline chemogenic limestone). More precisely, the richest is the lower part of the alluvial deposits where the fragments of all the nine rock types occur. The upper part of the alluvium is markedly poorer because only the five rock types occur there. Diversity of the petrographic composition of the alluvium decreased by reducing the local Podillian types of rocks, which are represented only by the red-coloured Devonian sandstones. The composition of the Carpathian types of rocks remained unchanged. The detected changes in the granulometric and petrographic composition of the alluvium of the investigated terrace permitted to show that the principal providers of the local (Podillian) debris of rocks was played by the Podillian tributaries of the Dnister River. The Dnister alone transported mainly the Carpathian material and only the small volume of Podillian rocks represented by the debris of the red-coloured Devonian sandstones. It was also found that the accumulation of the alluvial deposits of the Susidovychi terrace in the Kulakivtsi section took place in the conditions of restructuring of the Dnister palaeodrainage system. In the initial stages of this terrace formation, the palaeo-Dnister was directed from the village Dobryvliany further north than today, and it entered into the present-day Tupa River valley at environs of the village Bedrykivtsi. In the vicinity of the village Bedrykivtsi, the palaeo-Dnister was turning sharply eastward and proceeded along the present-day river valleys of Tupa and Seret. In the later stages of the Susidovychi terrace formation, the palaeo-Dnister left the portion of its valley stretching between the villages Bedrykivtsi and Schytivtsi, and it shifted several hundred meters to the south and has stopped practically within its current canyon valley. The desolate portion of its palaeo-valley located between the villages Bedrykivtsy and Kasperivtsi has been inherited by the Tupa River and the lower portion of this palaeo-valley located between the villages Kasperivtsi and Schytivtsi – by the Seret River. Key words: palaeo-Dnister, over the canyon terraces, Susidovychi terrace, alluvium, granulometric composition, petrographical composition, roundness, Carpathian material, Podillian material.
7
Johnson, Philip L., Samuel W. Nolan, and Patrick O. Shires. "Geologic Model for Alluvium-Buttressed Landslides." Environmental & Engineering Geoscience 29, no. 4 (November 1, 2023): 231–43. http://dx.doi.org/10.21663/eeg-d-22-00095.
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Abstract Large, deep-seated landslides typically occur in hillside settings without any natural buttressing, and many of these landslides remain relatively unstable and prone to reactivation. However, where large, deep-seated landslides have moved into incised valleys that subsequently experienced alluvial aggradation, a natural buttress of alluvium may cover the toes of these landslides, increasing stability. This study presents three examples of large, deep-seated landslides that are buttressed by Quaternary alluvium. The McCracken Hill Landslide in southern California and the Potrero Canyon Landslide Complex in central California are proximal to the Pacific coast. The Knights Valley Landslide Complex in northern California is much farther inland than the other examples. We analyzed the stability of one of the example landslides to demonstrate that a buttress of alluvium increases stability. In most settings, base level primarily controls alluvial aggradation. Base-level rise may result from either climatically driven late Quaternary eustatic sea-level rise or local factors such as damming of streams or downstream tectonic uplift. Late Quaternary eustatic sea-level rise caused alluvial aggradation at the McCracken Hill and Potrero Canyon sites. Downstream tectonic uplift likely caused local base-level rise and alluvial aggradation at Knights Valley.
8
Rucker, M. L., K. C. Fergason, and B. B. Panda. "Subsidence characterization and modeling for engineered facilities in Arizona, USA." Proceedings of the International Association of Hydrological Sciences 372 (November 12, 2015): 59–62. http://dx.doi.org/10.5194/piahs-372-59-2015.
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Abstract. Several engineered facilities located on deep alluvial basins in southern Arizona, including flood retention structures (FRS) and a coal ash disposal facility, have been impacted by up to as much as 1.8 m of differential land subsidence and associated earth fissuring. Compressible basin alluvium depths are as deep as about 300 m, and historic groundwater level declines due to pumping range from 60 to more than 100 m at these facilities. Addressing earth fissure-inducing ground strain has required alluvium modulus characterization to support finite element modeling. The authors have developed Percolation Theory-based methodologies to use effective stress and generalized geo-material types to estimate alluvium modulus as a function of alluvium lithology, depth and groundwater level. Alluvial material modulus behavior may be characterized as high modulus gravel-dominated, low modulus sand-dominated, or very low modulus fines-dominated (silts and clays) alluvium. Applied at specific aquifer stress points, such as significant pumping wells, this parameter characterization and quantification facilitates subsidence magnitude modeling at its' sources. Modeled subsidence is then propagated over time across the basin from the source(s) using a time delay exponential decay function similar to the soil mechanics consolidation coefficient, only applied laterally. This approach has expanded subsidence modeling capabilities on scales of engineered facilities of less than 2 to more than 15 km.
9
Qinghai, Xu, Yang Xiaolan, Wu Chen, Meng Lingyao, and Wang Zihui. "Alluvial Pollen on the North China Plain." Quaternary Research 46, no. 3 (November 1996): 270–80. http://dx.doi.org/10.1006/qres.1996.0066.
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Mordern alluvial pollen varies with geomorphic setting and depositional facies in sediments of the Yellow, Hutuo, and Luan rivers and in Baiyangdian and Hengshuihu lakes. Most of the arboreal pollen is derived from the mountains, whereas most of the nonarboreal pollen is derived from the plain itself. Alluvium dominated by Pinus pollen and Selaginella spores was deposited during a flood. Hydrodynamic sorting of alluvial pollen exists in the sediments of floodplain, central bar, natural levees, and point bar. In reconstructing the ancient vegetation and past climate based on pollen in alluvium, it is important to consider sedimentary facies and geomorphologic setting.
10
Bai, Zhong Sheng. "The Application of Surrounding Rock Controlling Technology on Mining of Alluvium Coal Pillar." Applied Mechanics and Materials 71-78 (July 2011): 2204–9. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.2204.
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In the alluvial coal pillar mining process, aiming at water prevention and cure, surrounding rock support, construction technology, safety management and the other main factors of safety mining, and through constant practice, the paper summarized the special measures of rock control on safety mining of alluvium coal pillar in the complex conditions for ensure safe of working face in alluvium corner coal, efficient mining, improve resource recovery. The economic and social effectiveness is remarkable.
11
Zolnikov, I. D., A. A. Anoykin, A. V. Postnov, A. V. Vybornov, E. A. Filatov, A. V. Vasilyev, and E. V. Parkhomchuk. "PROBLEMS OF DIFFERENTIATION AND CORRELATION OF ALLUVIAL DEPOSITS OF THE NEO-PLEISTOCENE IN THE LOWER OB REGION." Geology and mineral resources of Siberia, no. 10s (December 2021): 18–27. http://dx.doi.org/10.20403/2078-0575-2021-10c-18-27.
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The Upper Neo-Pleistocene alluvial deposits lie in a close hypsometric position in outcrops of the Lower Ob Region right bank. Their top usually does not rise above the level of 5 m above the tow-path edge. At the same level, glacial erratic masses of the Middle Pleistocene alluvium were recorded in a number of areas. The height of the 1st and 2nd sites of terraces (on average from 5 to 10–15 m) depends on the thickness of subaerial deposits overlapping the alluvium. The 3rd terrace above flood-plain of the Bolshaya (Big) Ob has no geomorphological expression, since the alluvium of the first Late Neo-Pleistocene interglacial period without ablation is drape overlain by parallely bedded precipitates of the glacier-ice-blocked lake of the first Late Neo-Pleistocene glaciation. Thus, the height of sites of terraced surfaces does not directly correlate with the age of their alluvial basement. Therefore, the geomorphological method for differentiation of river sediments is not effective for this region. In addition, the problems of differentiation and correlation of alluvial deposits of the Lower Ob Region right bank are complicated by the presence of fluvioglacial incisions of deglaciation stages of the Middle Neo-Pleistocene and Upper Neo-Pleistocene glaciations.
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Heizler, Matthew T., Karl E. Karlstrom, Micael Albonico, Richard Hereford, L. Sue Beard, Steven M. Cather, Laurie J. Crossey, and Kurt E. Sundell. "Detrital sanidine 40Ar/39Ar dating confirms <2 Ma age of Crooked Ridge paleoriver and subsequent deep denudation of the southwestern Colorado Plateau." Geosphere 17, no. 2 (February 25, 2021): 438–54. http://dx.doi.org/10.1130/ges02319.1.
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Abstract Crooked Ridge and White Mesa in northeastern Arizona (southwestern United States) preserve, as inverted topography, a 57-km-long abandoned alluvial system near the present drainage divide between the Colorado, San Juan, and Little Colorado Rivers. The pathway of this paleoriver, flowing southwest toward eastern Grand Canyon, has led to provocative alternative models for its potential importance in carving Grand Canyon. The ∼50-m-thick White Mesa alluvium is the only datable record of this paleoriver system. We present new 40Ar/39Ar sanidine dating that confirms a ca. 2 Ma maximum depositional age for White Mesa alluvium, supported by a large mode (n = 42) of dates from 2.06 to 1.76 Ma. Older grain modes show abundant 37–23 Ma grains mostly derived ultimately from the San Juan Mountains, as is also documented by rare volcanic and basement pebbles in the White Mesa alluvium. A tuff with an age of 1.07 ± 0.05 Ma is inset below, and hence provides a younger age bracket for the White Mesa alluvium. Newly dated remnant deposits on Black Mesa contain similar 37–23 Ma grains and exotic pebbles, plus a large mode (n = 71) of 9.052 ± 0.003 Ma sanidine. These deposits could be part of the White Mesa alluvium without any Pleistocene grains, but new detrital sanidine data from the upper Bidahochi Formation near Ganado, Arizona, have similar maximum depositional ages of 11.0–6.1 Ma and show similar 40–20 Ma San Juan Mountains–derived sanidine. Thus, we tentatively interpret the <9 Ma Black Mesa deposit to be a remnant of an 11–6 Ma Bidahochi alluvial system derived from the now-eroded southwestern fringe of the San Juan Mountains. This alluvial fringe is the probable source for reworking of 40–20 Ma detrital sanidine and exotic clasts into Oligocene Chuska Sandstone, Miocene Bidahochi Formation, and ultimately into the <2 Ma White Mesa alluvium. The <2 Ma age of the White Mesa alluvium does not support models that the Crooked Ridge paleoriver originated as a late Oligocene to Miocene San Juan River that ultimately carved across the Kaibab uplift. Instead, we interpret the Crooked Ridge paleoriver as a 1.9–1.1 Ma tributary to the Little Colorado River, analogous to modern-day Moenkopi Wash. We reject the “young sediment in old paleovalley” hypothesis based on mapping, stratigraphic, and geomorphic constraints. Deep exhumation and beheading by tributaries of the San Juan and Colorado Rivers caused the Crooked Ridge paleotributary to be abandoned between 1.9 and 1.1 Ma. Thermochronologic data also provide no evidence for, and pose substantial difficulties with, the hypothesis for an earlier (Oligocene–Miocene) Colorado–San Juan paleoriver system that flowed along the Crooked Ridge pathway and carved across the Kaibab uplift.
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Zhang, L., G. Parker, C. P. Stark, T. Inoue, E. Viparelli, X. Fu, and N. Izumi. "Macro-roughness model of bedrock–alluvial river morphodynamics." Earth Surface Dynamics 3, no. 1 (February 11, 2015): 113–38. http://dx.doi.org/10.5194/esurf-3-113-2015.
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Abstract. The 1-D saltation–abrasion model of channel bedrock incision of Sklar and Dietrich (2004), in which the erosion rate is buffered by the surface area fraction of bedrock covered by alluvium, was a major advance over models that treat river erosion as a function of bed slope and drainage area. Their model is, however, limited because it calculates bed cover in terms of bedload sediment supply rather than local bedload transport. It implicitly assumes that as sediment supply from upstream changes, the transport rate adjusts instantaneously everywhere downstream to match. This assumption is not valid in general, and thus can give rise to unphysical consequences. Here we present a unified morphodynamic formulation of both channel incision and alluviation that specifically tracks the spatiotemporal variation in both bedload transport and alluvial thickness. It does so by relating the bedrock cover fraction to the ratio of alluvium thickness to bedrock macro-roughness, rather than to the ratio of bedload supply rate to capacity bedload transport. The new formulation (MRSAA) predicts waves of alluviation and rarification, in addition to bedrock erosion. Embedded in it are three physical processes: alluvial diffusion, fast downstream advection of alluvial disturbances, and slow upstream migration of incisional disturbances. Solutions of this formulation over a fixed bed are used to demonstrate the stripping of an initial alluvial cover, the emplacement of alluvial cover over an initially bare bed and the advection–diffusion of a sediment pulse over an alluvial bed. A solution for alluvial–incisional interaction in a channel with a basement undergoing net rock uplift shows how an impulsive increase in sediment supply can quickly and completely bury the bedrock under thick alluvium, thus blocking bedrock erosion. As the river responds to rock uplift or base level fall, the transition point separating an alluvial reach upstream from an alluvial–bedrock reach downstream migrates upstream in the form of a "hidden knickpoint". A tectonically more complex case of rock uplift subject to a localized zone of subsidence (graben) yields a steady-state solution that is not attainable with the original saltation–abrasion model. A solution for the case of bedrock–alluvial coevolution upstream of an alluviated river mouth illustrates how the bedrock surface can be progressively buried not far below the alluvium. Because the model tracks the spatiotemporal variation in both bedload transport and alluvial thickness, it is applicable to the study of the incisional response of a river subject to temporally varying sediment supply. It thus has the potential to capture the response of an alluvial–bedrock river to massive impulsive sediment inputs associated with landslides or debris flows.
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Zhang, L., G. Parker, C. P. Stark, T. Inoue, E. Viparelli, X. Fu, and N. Izumi. "Macro-roughness model of bedrock-alluvial river morphodynamics." Earth Surface Dynamics Discussions 2, no. 1 (May 27, 2014): 297–355. http://dx.doi.org/10.5194/esurfd-2-297-2014.
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Abstract. The 1-D saltation-abrasion model of channel bedrock incision of Sklar and Dietrich, in which the erosion rate is buffered by the surface area fraction of bedrock covered by alluvium, was a major advance over models that treat river erosion as a function of bed slope and drainage area. Their model is, however, limited because it calculates bed cover in terms of bedload sediment supply rather than local bedload transport. It implicitly assumes that as sediment supply from upstream changes, the transport rate adjusts instantaneously everywhere downstream to match. This assumption is not valid in general, and thus can give rise unphysical consequences. Here we present a unified morphodynamic formulation of both channel incision and alluviation which specifically tracks the spatiotemporal variation of both bedload transport and alluvial thickness. It does so by relating the cover fraction not to a ratio of bedload supply rate to capacity bedload transport, but rather to the ratio of alluvium thickness to a macro-roughness characterizing the bedrock surface. The new formulation predicts waves of alluviation and rarification, in addition to bedrock erosion. Embedded in it are three physical processes: alluvial diffusion, fast downstream advection of alluvial disturbances and slow upstream migration of incisional disturbances. Solutions of this formulation over a fixed bed are used to demonstrate the stripping of an initial alluvial cover, the emplacement of alluvial cover over an initially bare bed and the advection–diffusion of a sediment pulse over an alluvial bed. A solution for alluvial-incisional interaction in a channel with a basement undergoing net rock uplift shows how an impulsive increase in sediment supply can quickly and completely bury the bedrock under thick alluvium, so blocking bedrock erosion. As the river responds to rock uplift or base level fall, the transition point separating an alluvial reach upstream from an alluvial-bedrock reach downstream migrates upstream in the form of a "hidden knickpoint". A solution for the case of a zone of rock subsidence (graben) bounded upstream and downstream by zones of rock uplift (horsts) yields a steady-state solution that is unattainable with the original saltation-abrasion model. A solution for the case of bedrock-alluvial coevolution upstream of an alluviated river mouth illustrates how the bedrock surface can be progressive buried not far below the alluvium. Because the model tracks the spatiotemporal variation of both bedload transport and alluvial thickness, it is applicable to the study of the incisional response of a river subject to temporally varying sediment supply. It thus has the potential to capture the response of an alluvial-bedrock river to massive impulsive sediment inputs associated with landslides or debris flows.
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Yatsyshyn, Andriy, and Oleksandr Khrypta. "Lithological characteristic of the channel facies of alluvium of Early Pleistocene terrace of the pra-Stryi river in the Bolekhiv section." Visnyk of the Lviv University. Series Geography 53 (December 18, 2019): 322–36. http://dx.doi.org/10.30970/vgg.2019.53.10682.
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The article highlighted main lithologic characteristics of channel facies alluvium, which is the most ancient within Morshynska hill of pra-Stryi terrace. Upper and central layers of alluvium section are found to have lenticular structure fixing lines of shallow (up to 1.0–1.2 m) palaeochannels 4–5 wide. Granulometric composition of alluvium of channel facies varies little up the incision. Its main component is the pebble and its content except the first one exceeds 50%. The content of other less spread components of the alluvial layer remains almost unchanged. The fact that there are no vivid changes in the granulometric composition of alluvium testifies the stability of conditions of accumulation of sediments in the bed course of palaeoflow. Petrographic composition of coarse fraction appeared to be immensely homogeneous due to the dominance of Carpathian sandstones. In particular, all boulders are composed of light-to-dark, fine-to-medium grained sandstones. Siltstones and silicites appear in the composition of pebble and gravel only, their content is insignificant and ranges from 1 to 6 %. Siltstones are yellowish-white and yellowish-brown, and silicites are dark grey and almost black. Analysis of roundness of coarse fraction alluvium has shown the predominance of fine-to-medium rounded grains in its content that, in its turn, testifies to long-distance transportation of fragmental matter. Besides, better roundness of clast is traced up the section. In particular, the number of poorly rounded clast in the boulders is decreasing and even well-rounded grains are appearing; the content of pebbles shows the decrease of poorly rounded clast and gradual increase of well-rounded pebbles. The samples of disc-like shape prevail in sampling material. Only boulders of sample 3 do not contain them at all. Samples of other shapes are less spread; first of all, it is spheroid and roller fragments. The lower part of the alluvium thickness contains the smallest amount of them. The content of blade fragments is the most consistent. Measurements of the imbrication of fragments testified them to have moved in the lower part of the alluvium thickness from northwest to the southeast that coincides with hypothetic flow of palaeo-Stryi during the formation of the terrace under investigation. The predominant direction of the palaeoflow in the upper part of alluvium accumulations has changed; there dominates the direction from southwest to northeast, which is closer to the direction of palaeo-Sukil flow. Taking into account relatively coarse content of alluvium, particularly, significant content of boulders and big pebbles and predominance of well-rounded fragments practically in all samples, it can be assumed that alluvium deposited in the bed of the pra-Stryi river, that flowed along the Carpathian escarpment to the southeast to the Svicha river during the formation of the terrace. Change in the direction of palaeoflow in the upper part of alluvium stratum may point out a local change in the direction of this river flow. Key words: terrace, pra-Stryi, alluvium, granulometric composition, petrographic composition, roundness, shape of fragments, Carpathian material.
16
Dowling, AJ, and EA Gardner. "Spatial variation in salinity of some alluvial aquifers in central Queensland - a steady state analysis." Soil Research 26, no. 4 (1988): 583. http://dx.doi.org/10.1071/sr9880583.
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This paper reports on the spatial variation of salinity in the alluvial groundwaters of the Callide Valley, central Queensland. The spatial distribution of salinity in this area is very complex with substantial variation occumng over small (< 1 km) and large (> 10 km) distances. This complexity has been attributed to variable leakage of highly saline water into the alluvium from adjacent hard rock aquifers. A simple but elegant steady-state dimensionless analysis is introduced to clearly establish if salt additions or subtractions are occurring in the alluvial groundwaters. By using ions not normally complicated by precipitation reactions (sodium and chloride), our analyses show that solutes are conserved, with excellent agreement between the measured data and theory. This result strongly supports a hypothesis of progressive concentration of a localized source of salt, introduced near the headwaters, with increasing distance down discrete alluvium-stream valleys. We conclude our paper with a caution on the delayed effects of distributed salt import into alluvial aquifers with large solute response times.
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Hunter, Mark A., and Timothy Quinn. "Summer Water Temperatures in Alluvial and Bedrock Channels of the Olympic Peninsula." Western Journal of Applied Forestry 24, no. 2 (April 1, 2009): 103–8. http://dx.doi.org/10.1093/wjaf/24.2.103.
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Abstract To better understand how stream geomorphology may affect water temperature, we recorded water temperatures along two channels, one with deep alluvium and the other composed of bedrock and shallow alluvium. Study channels were located in managed forestlands on the Olympic Peninsula. Water temperatures were recorded hourly at 75-m intervals along 1.6 and 1.4 km of the alluvial and bedrock channels, respectively, during the summers of 2003 and 2004. Seasonal maximum and minimum daily water temperatures (i.e., season-long means for individual temperature dataloggers) in the alluvial channel tended to vary less over the course of the summer than temperatures in the bedrock channel. In addition, the means of all the individual dataloggers' daily maximums for each stream (reach mean maximum) and, similarly, the daily minimums (reach mean minimum) varied less for the alluvial channel. Changes in temperature from the upstream to downstream were greater for the bedrock channel, but only at low flow.
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Fuladi, A., and M. S. Deshmukh. "Geomorphic Characteristics of WRC-1 Watershed, Chargarh River Basin, Central India: Possible Implications on Hydrogeological Status." Journal of Scientific Research 15, no. 3 (August 16, 2023): 607–19. http://dx.doi.org/10.3329/jsr.v15i3.63239.
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Every geomorphic feature has its own distinct impact on the static groundwater level(SWL), seasonal water table fluctuation(WTF) and yield of the wells. The aim of this study was to analyze the role of geomorphic features over the groundwater regime and its possible implications on hydrogeological status within WRC-1 watershed. The watershed is covered by the Deccan basalt lavaflows and Quaternary alluvium. The geomorphic units of study area are HDP, MDP, residual hill, valleyfills, scarp, pediment, pediplain, butte, alluvial plain and gullied land to identify the relationship between geomorphic units and corresponding hydrogeological status. The pre-monsoon SWL, WTF and yield of the open-dug wells are analyzed. The high groundwater level fluctuation is indicated by residual hill, plateau remnant, HDP, MDP, pediment as compared to pond, river, younger alluvial plain and pediplain. Pre-monsoon yield of dugwells in river older alluvium are comparatively high; butte, residual hill, pond, river, dam/reservoir and valley fill which are comparatively moderate to low. The overall findings indicate that seasonal WLF in the hard rock terrain(basalt) is high compared to soft rock formation(alluvium).The best suitable area identified is Pediplain which is categorized as very good groundwater prospectus zone with pre-monsoon SWL(5.8mbgl), WTF(3.1m) and yield of the well(108000liter/day) respectively.
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LU, NGAN THI, YI-FAN DUAN, and LI-BING ZHANG. "Polystichum alluvium (subg. Haplopolystichum; Dryopteridaceae), a new cave species from Guizhou, China, with reference to new distribution records of P. leveillei." Phytotaxa 323, no. 1 (September 26, 2017): 88. http://dx.doi.org/10.11646/phytotaxa.323.1.8.
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A new fern species, Polystichum alluvium, a member of P. subg. Haplopolystichum (Dryopteridaceae), is described from Guizhou Province in Southwest China. Polystichum alluvium is similar to P. lanceolatum in having small habit and subcoriaceous pinnae, but the former has oblanceolate laminae with basal pinnae strongly contracted toward lamina base, deltoid-ovate and sessile pinnae, and very short spinules on acroscopic pinna margins or no spinules, while the latter has lanceolate laminae with basal pinnae not contracted toward lamina base, oblong and petiolate pinnae, and long spinules on acroscopic pinna margins. Polystichum alluvium was found from the alluvial bottom of a karst cave at an elevation of 1410 m with humid and shady conditions and is currently known from one population with ca. 50 plants in western Guizhou. It is classified as Critically Endangered (CR) following IUCN Red List criteria. We also expanded the distribution of P. leveillei to southern-central Guizhou based on our new collections.
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Schwarz, Erik J. "Distinguishing buried alluvium from till by using detailed total-magnetic-field data." Canadian Journal of Earth Sciences 27, no. 4 (April 1, 1990): 513–19. http://dx.doi.org/10.1139/e90-047.
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Total-magnetic-field and vertical-magnetic-gradient profiles are characteristically different over alluvial and glacial sediments. Positive magnetic anomalies elongated in the river-valley direction but not in the structural trend of the underlying bedrock indicate the occurrence of magnetite enrichments within the alluvium. No evidence for such anomalies is found in survey data obtained in gravel pits located in tills. The logarithm of the power of the total-field profiles over the river terraces plotted against spatial frequency is structured, which is indicative of the presence of magnetic sources of certain depth and width. However, the power spectra over till may also show similar features if high-frequency bedrock anomalies are present in the data, so these spectra are not a reliable means of distinguishing between buried alluvium and till. The results show that magnetic analysis allows the discrimination between buried tills and alluvium in which magnetite concentrations of considerable lateral extent were formed.
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Teng, Tsung-Jen, Juin-Fu Chai, and Chau-Shioung Yeh. "Determination of Resonance Frequency of Two-Dimensional Alluvial Valley by Background Phase Subtraction Method." Journal of Mechanics 14, no. 1 (March 1998): 1–15. http://dx.doi.org/10.1017/s1727719100000010.
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ABSTRACTThis paper is to develop the background phase subtraction method to determine the resonance frequency of a two-dimensional alluvial valley subjected to an incident plane SH-wave. The scattered wave due to the alluvium can be expressed in a series of basis functions, and the associated coefficients are related to the coefficients of free field by the so-called T-matrix method. By applying the resonance scattering theory, the effects among all normal modes can be decoupled and hence one can obtain the phase shift of each eigen partial wave. Similarly, the phase shift of each eigen partial wave due to a canyon with the same geometrical shape of the alluvium can be determined, and is recognized as the background effect. Furthermore, based on the phase represented scattering matrix, the resonance frequencies of each normal mode and its overtones can be determined by the subtraction of the associated phase dependent function due to the canyon from that due to the alluvium.
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Fall, Patricia L. "Pollen Taphonomy in a Canyon Stream." Quaternary Research 28, no. 3 (November 1987): 393–406. http://dx.doi.org/10.1016/0033-5894(87)90006-8.
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AbstractSurface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae-Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.
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Gossmann, Simon, Stephen Denner, St John Herbert, Sanjeev Pandey, Randall Cox, Mark Gallagher, and Josh Moncrieff. "Evaluating potential coal seam gas impacts to the Condamine Alluvium: an example of successful community involvement." APPEA Journal 56, no. 2 (2016): 546. http://dx.doi.org/10.1071/aj15052.
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The groundwater resources of the Condamine River Alluvial Aquifer (Condamine Alluvium) in Queensland have been developed in the past 60 years for irrigation, stock, domestic and other uses. Extraction of more than 55,000 mL/yr from this aquifer is critical to supporting the local irrigation industry. Existing and proposed coal seam gas development in the Surat Basin extends to underneath the western edge of the CA footprint and involves depressurisation of coals that form up to 10% of the Walloon Coal Measures (WCM) at some depth below the alluvium. Reduced groundwater availability from the already-stressed Condamine Alluvium is thus an oft-quoted concern of landholders when further development of the CSG industry is considered. An extensive study, led by the Queensland Office of Groundwater Impact Assessment (OGIA) and supported by Arrow Energy, was carried out to provide quantitative assessments of vertical hydraulic conductivity between the alluvium, coal measures and intervening formations. This extended abstract focuses on one element of the aforementioned study led by Arrow Energy, specifically, aquifer testing undertaken at two representative sites overlying the Condamine Alluvium. This included drilling and collection of core; geophysical, geomechanical and geochemical testing; test pumping and monitoring; and, modelling. An important element of this project, aside from sharing of data and results—was the involvement of local landholders in development of the investigations, and attendance at field days during drilling and presentation of results. Key findings included estimated ranges of vertical hydraulic conductivity derived from parameter estimation modelling that were lower than previously suggested.
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Shopov, Vladimir, Yordan Evlogiev, and Nikolai Popov. "Correlation between the Quaternary continental sediments in North-eastern Bulgaria with the marine sediments in the Black Sea Shelf." Geologica Balcanica 24, no. 5 (October 30, 1994): 3–10. http://dx.doi.org/10.52321/geolbalc.24.5.3.
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North-eastern Bulgaria was an extraglacial region during the Quaternary. The active erosion and abrasion in this region is connected with the pluvial facies of the glaciation epoch. The alluvial sediments in the terraces – T0-T6, accumulated during the relevant glacial and stacial cycles were sources of fine grained loess. The loess accumulated from a given cycle lies over the older terraces and levels then denuded for eolian sedimentation. The active eolian activity has to be connected with the deglaciation phases of the glaciers. From the beginning of the Quaternary the effects of five big glaciations corresponding to the regressions of the sea are marked in the Black Sea region. These are: Dunavium, Günz, Mindel, Riss and Würm. The alluvial soil on the seventh loess reveals that there has been a break in sedimentation - the regression of Günz 2. The alluvium of sixth loess - the Mindel regression, that of fifth loess - the regression of Riss 1 and the alluvium of fourth loess - maybe the regression of Riss 2. The alluvium of third loess (corresponding lo the glaciation (W1) - the Post-Karangatian regression, this of second loess (W2) - the break which caused the deposition of continental sediments over the Lower New Euxinian Substage and this on first loess (W3) - the regression between the Upper Pleistocene and Holocene sediments. The break, in recent soil time, probably corresponds to the Fanagorian regression.
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Heritage, G., S. Tooth, N. Entwistle, and D. Milan. "Long-term flood controls on semi-arid river form: evidence from the Sabie and Olifants rivers, eastern South Africa." Proceedings of the International Association of Hydrological Sciences 367 (March 3, 2015): 141–46. http://dx.doi.org/10.5194/piahs-367-141-2015.
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Abstract. Rivers in the Kruger National Park, eastern South Africa, are characterised by bedrock-influenced "macrochannels" containing variable alluvial thicknesses and riparian vegetation assemblages. Evidence from the Sabie and Olifants rivers suggests that flows up to moderate floods (<3500 m3 s−1) tend to result in net alluviation, with sediments gradually covering the underlying bedrock. More extreme floods strip alluvium and erode bedrock, effectively exerting the primary control over long-term river morphologic development. On the Olifants River, post-flood aerial LIDAR imagery reveals that the 2012 extreme flood (~14000 m3 s−1) resulted in extensive stripping of stored alluvial sediment, exposing and eroding the underlying weathered bedrock. On the Sabie River, preliminary optically stimulated luminescence ages for remnant alluvium are all less than 1000 years, highlighting typical timescales of sediment storage. Together, these results suggest that while periods of general alluviation occur on these systems, long-term river development results from extreme flood-generated bedrock erosion.
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Miller, Richard D., Don W. Steeples, and Michael Brannan. "Mapping a bedrock surface under dry alluvium with shallow seismic reflections." GEOPHYSICS 54, no. 12 (December 1989): 1528–34. http://dx.doi.org/10.1190/1.1442620.
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Shallow seismic‐reflection techniques were used to image the bedrock‐alluvial interface, near a chemical evaporation pond in the Texas Panhandle, allowing optimum placement of water‐quality monitor wells. The seismic data showed bedrock valleys as shallow as 4 m and accurate to within 1 m horizontally and vertically. The normal‐moveout velocity within the near‐surface alluvium varies from 225 m/s to 400 m/s. All monitor‐well borings near the evaporation pond penetrated unsaturated alluvial material. On most of the data, the wavelet reflected from the bedrock‐alluvium interface has a dominant frequency of around 170 Hz. Low‐cut filtering at 24 dB/octave below 220 Hz prior to analog‐to‐digital conversion enhanced the amplitude of the desired bedrock reflection relative to the amplitude of the unwanted ground roll. The final bedrock contour map derived from drilling and seismic‐reflection data possesses improved resolution and shows a bedrock valley not interpretable from drill data alone.
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Zolnikov, I. D., and E. V. Deev. "STRATIGRAPHICAL SIGNIFICANCE OF THE GORNY ALTAI ALLUVIAL DEPOSITS IN THE LATE PLEISTOCENE AND HOLOCENE." Geology and mineral resources of Siberia, no. 10s (December 2021): 28–35. http://dx.doi.org/10.20403/2078-0575-2021-10c-28-35.
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It is shown that representative sections of the Late Pleistocene alluvial deposits are found mainly in planations of main valleys and intermountain basins of the Gorny Altai. The data of optically stimulated luminescence and radiocarbon dating characterizing the Malyi Yaloman alluvium in the stratotypic Malyi Yaloman section and in same-age reference sections in the upper, middle and lower reaches of the Katun River are presented. That implied the regional stratigraphical significance of the Malyi Yaloman alluvium and it attribution to the epoch separating two Late Quaternary glaciations of the Gorny Altai. The question is raised of the need to identify the stratigraphical significance of regional and local events that caused not only glacial, but also seismic damming of the Gorny Altai valleys in the Late Pleistocene.
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Fenton, Cassandra R., and Jon D. Pelletier. "Cosmogenic 3He age estimates of Plio-Pleistocene alluvial-fan surfaces in the Lower Colorado River Corridor, Arizona, USA." Quaternary Research 79, no. 1 (January 2013): 86–99. http://dx.doi.org/10.1016/j.yqres.2012.10.006.
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AbstractPlio-Pleistocene deposits of the Lower Colorado River (LCR) and tributary alluvial fans emanating from the Black Mountains near Golden Shores, Arizona record six cycles of Late Cenozoic aggradation and incision of the LCR and its adjacent alluvial fans. Cosmogenic 3He (3Hec) ages of basalt boulders on fan terraces yield age ranges of: 3.3–2.2 Ma, 2.2–1.1 Ma, 1.1 Ma to 110 ka, < 350 ka, < 150 ka, and < 63 ka. T1 and Q1 fans are especially significant, because they overlie Bullhead Alluvium, i.e. the first alluvial deposit of the LCR since its inception ca. 4.2 Ma. 3Hec data suggest that the LCR began downcutting into the Bullhead Alluvium as early as 3.3 Ma and as late as 2.2 Ma. Younger Q2a to Q4 fans very broadly correlate in number and age with alluvial terraces elsewhere in the southwestern USA. Large uncertainties in 3Hec ages preclude a temporal link between the genesis of the Black Mountain fans and specific climate transitions. Fan-terrace morphology and the absence of significant Plio-Quaternary faulting in the area, however, indicate regional, episodic increases in sediment supply, and that climate change has possibly played a role in Late Cenozoic piedmont and valley-floor aggradation in the LCR valley.
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Rasskazov, S. V., A. Al Hamud, A. Hassan, N. V. Kulagina, I. S. Chuvashova, T. A. Yasnygina, and R. C. Budaev. "Литогеохимические и палинологические показатели палеоклимата раннего плиоцена в озерных отложениях из разреза манзурского аллювия (Предбайкалье)." Geology and Environment 2, no. 1 (2022): 45–83. http://dx.doi.org/10.26516/2541-9641.2022.1.45.
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The Manzurka alluvium is a polychronous complex of accumulations of sand and pebbles in the Pliocene-Early Pleistocene Proto-Manzurka paleovalley. Layers of fine-grained (aleurite and clay) material are rare in the alluvium. In the earliest (Buguldeika) alluvial horizon of the paleovalley, a 3-meter lacustrine lens of horizontally layered fine-fragmented sediments was found, in which a fairly uniform composition of spore-pollen spectra was determined and a distinct change in lithogeochemical indicators from weak weathering of material in the foot to strong – in the roof of the lens was revealed. From change in the lithogeochemical characteristics of the lacustrine sediments, an episode of early Pliocene paleoclimatic variations of cold and heat was established. It occurred on background of the conservative existence of forest vegetation of warm and humid climate.
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Rains, R. Bruce, James A. Burns, and Robert R. Young. "Postglacial alluvial terraces and an incorporated bison skeleton, Ghostpine Creek, southern Alberta." Canadian Journal of Earth Sciences 31, no. 10 (October 1, 1994): 1501–9. http://dx.doi.org/10.1139/e94-133.
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Ghostpine Creek near Three Hills, southern Alberta, is a tributary of the Red Deer River. It has three sets of paired alluvial terraces (T-1 to T-3) in a downstream part of the valley. The rare discovery of a largely intact skeleton of plains bison (Bison bison bison) in a T-2 point bar prompted terrace mapping, 14C dating, and interpretation of the postglacial evolution of the valley. Downvalley portions of the creek began incision into the newly drained bed of glacial Lake Drumheller probably about 13 000 BP. Localized valley deepening up to 20 m, the production of erosional benches and residual spurs, and the development of partly convex-up creek paleothalwegs occurred between about 13 000 and 7600 BP, by which time basal T-1 alluvium was beginning to accumulate. Subsequent aggradation of T-1 sediment and then degradation of about 3–4 m were followed by aggradation of T-2 alluvium. These trends had taken place by 2600 BP, when the bison died and its skeletal remains were buried in uppermost sediment of a T-2 point bar. Between 2600 BP and now, the creek incised about 5 m below the former T-2 channel position and aggraded, partly synchronously, up to 3 m of T-3–floodplain alluvium. Radiocarbon-dated alluvial terrace sequences in Alberta show generally comparable trends of rapid early creek incision followed by partially overlapping episodes of net aggradation and degradation from basin to basin. However, such episodes were not closely synchronized between basins.
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El Hassan, Osman M. "Resistivity survey investigating salinity hazard and aquifer system in the alluvial fans in central Jordan Valley." Journal of The Faculty of Science and Technology, no. 5 (October 5, 2018): 54–66. http://dx.doi.org/10.52981/jfst.vi5.366.
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In the course of this study geological and geophysical resistivity survey were conducted in the area extended from Deir Alla to Suleikhat (Middle Ghor Area) in Jordan valley. In order to evaluate the potential and characteristic of the groundwater quality and distribution of the aquifer in the alluvial in the area. The aquifer system in the area consists of Ajlun and Belga Group, in addition to the Plateau Gravel Group and the Alluvial Aquifers.The resistivity survey encounter an average thickness of the alluvial fans of about93 meters. The source of salinity in the alluvium aquifers was predicted to be Lisan Formation, which underlies the Whole alluvium in the area.Quantitative interpretation of VES data coupled with field and preexisted electrical conductivity reading work out the following characteristic for water bearing layer in the alluvial fan deposits: The alluvial fans exhibit recurrently lateral variation, even in the same area.The continuity of static water table may be interrupted by mud dominated area. These facts forearm to conclude that the aquifer system in the alluvial fans are lenses to micro-aquifers bodies of saturated gravel and sand dominated layers, with resistivity range between 30-60 ohm.m, with apposite thickness range of 8-42 meters.Calculated Porosity ofsuch aquifers is approximated to be in range of 20-27%. In addition to these layers there is a mud gravel layerswith resistivity ranges from 20 to 30 ohm.m, their thickness are in range of 5-23 meters, and their porosity is approximated to 33%.
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Bondar, Kseniia, Bogdan Ridush, Mariia Baryshnikova, and Yana Popiuk. "On palaeomagnetic dating of fluvial deposits in the section of Neporotove gravel quarry on the Middle Dniester." Journal of Geology, Geography and Geoecology 28, no. 2 (July 3, 2019): 241–49. http://dx.doi.org/10.15421/111925.
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The paper presents the results of palaeomagnetic studies of Quaternary noncemented deposits from the section of Neporotove on the VIIIth terrace of the Dniester River valley with abnormal thickness (more than 20 m) of the channel alluvium near the village of Neporotove, located on the right bank of the Dniester River. Alluvial facies of river terraces’ deposits are valuable palaeogeographic archives but not quite complete. They are affected by denudation and often do not contain fossils. The possible way for their dating is provided by a palaeomagnetic method performed on suitable for sampling underlying and overlying beds. The alluvial sequence consists of four units. Unit I is composed of inclined gravel-pebble layers with the sand filler with a visible thickness of about 8 m. Unit II has bedded over the denudated surface of Unit I; it consists of light-yellow laminated aleurit loam, 5-30 cm thick underlaid by 0.5-1.5 bed of fine sand. We consider Unit II to be lacustrine deposits accumulated in quiet water. Unit III is represented with inclined or sub-horizontally layered gravel-pebble-boulder deposits with up to 10 m of visible thickness. It includes boulders and blocks of sedimentary rocks up to 1.0 in diameter, considered as drop-stones. In the roof of the gravel-pebble Unit III, there is the white carbonate layer, probably, the illuvial horizon of the palaeosol (mr1), which transited up into the brownish-red horizon A (Unit IV). Unit IV – dark-red sandy-gravel horizon, pedosediment, probably partly the reworked material washed into ice wages in the roof of Unit III. As a result of alternating field stepwise demagnetisation of natural remanence of sediments, we determined that loamy Unit II, which separates members of gravel stratum, and sandy Unit IV, which overlays packs of gravel alluvium, bear characteristic remanent magnetisation (RM) with normal geomagnetic polarity. Taking into consideration lithology and two-fold structure of terrace gravel alluvium as well as palaeomagnetic results, we assume the lacustrine deposits of Unit II was formed during Jaramillo palaeomagnetic subchron corresponding to the end of Shyrokyne Stage, and a pedosediment of Unit IV was formed during Martonosha Stage. The upper alluvial suite of a terrace (Unit III) was generally deposited during a cold stage,directly prior to the onset of lacustrine loam sedimentation, while the lower alluvial member (Unit I) dates from the preceding warm stage. Thus, we defined the geological age of the whole channel alluvium strata of the VIIIth Dniester terrace as Shyrokyne-Pryazovya Stage.
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Räsänen, Matti, Ron Neller, Jukka Salo, and Högne Jungner. "Recent and ancient fluvial deposition systems in the Amazonian foreland basin, Peru." Geological Magazine 129, no. 3 (May 1992): 293–306. http://dx.doi.org/10.1017/s0016756800019233.
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AbstractStill active Sub-Andean foreland deformation is suggested to have syndepositionally modified the fluvial depositional environments in the Peruvian Amazonian foreland basin throughout Neogene-Quaternary time. Modern fluvial aggradation continues to proceed on a large scale (c. 120 000 km2) in two differing depositional systems. Firstly, various multistoried floodbasin deposits are derived from the meandering and anastomosing rivers within the subsiding intraforeland basins. Secondly, in the northern part of the Pastaza-Marañon basin the largest known Holocene alluvial fan-like formation (c. 60 000 km2) composed of reworked, volcaniclastic debris derived from active Ecuadorian volcanoes, has been identified.The widespread, poorly known, dissected surface alluvium (terra firme) which covers the main part of the Peruvian Amazonian foreland basin shows further evidence of long-term foreland deformation, and terraces indicate both the effects of tectonism and Pleistocene climatic oscillations. In northern Peru, the surface alluvium was deposited by a Tertiary fluvial system with palaeocurrents to the west and northwest into the Andean foreland basin. In southern Peru, the respective surficial alluvium was part of a post-Miocene fluvial system flowing northeast into the main Amazon basin. Both systems were gradually abandoned when the eastward migrating Andean foreland deformation led to the more distinctive partitioning of the intraforeland basins, and the modern drainage system was created.
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Ferry, B. W., and E. Lodge. "Distribution and Succession of Lichens Associated with Prunus Spinosa at Dungeness, England." Lichenologist 28, no. 2 (March 1996): 129–43. http://dx.doi.org/10.1006/lich.1996.0012.
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AbstractThe distribution and succession of epiphytic and other associated lichens on blackthorn (Prunus spinosa) growing on the shingle at Dungeness is described. Some 33 epiphytic species, which exhibited a range of ecological strategies from pioneer to late colonizers, were recorded. Both the rate of change of status (age) of blackthorns and the progress of lichen colonization seemed to depend on whether the bushes were growing directly on shingle or on adjacent alluvial soil; both processes seeming to be more rapid on the former substratum. Terricolous lichens, of which 18 were recorded, generally appeared late in the succession and mostly amongst bushes growing on shingle. Rabbits often invaded the blackthorns, especially those on alluvium, and probably contributed to the lack of terrestrial lichens under these bushes. Blackthorns growing on shingle tended to be more prostrate in form than those on alluvium.
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Thorp, Martin, and Peter Glanville. "A mid-Holocene alluvial deposit beneath blanket peat in the Upper Liffey Valley, county Wicklow, Ireland." Irish Geography 35, no. 2 (August 11, 2014): 185–96. http://dx.doi.org/10.55650/igj.2002.238.
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A 750m section on a hillside in the upper Liffey Valley, county Wicklow has exposed a small valley buried beneath blanket peat. The section shows two alluvial sequences underlain by a stone line over regional till and weathered granite. 14C dates from wood in the sediments indicate that the older alluvium formed between 4950-4550 cal. BP and the younger between 3470-3000 cal. BP. Wood in the basal layer of the overlying peat yielded a date of 2310-2150 cal. BP. The younger alluvium shows the effects of soil paludification prior to the peat expansion and dated pollen analyses elsewhere in the upper catchment show that blanket peat began spreading over most areas above 350m after 4000-3600 BP. The buried valley contributed sediments to the mid-Holocene floodplains in the upper Liffey valley prior to the extension of blanket peat.
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Sirajuddin, Haerany, and Sri Maulidani. "Analisis Profil Bawah Permukaan Pantai Lumpue Kota Parepare." Jurnal Penelitian Enjiniring 23, no. 2 (November 30, 2019): 186–94. http://dx.doi.org/10.25042/jpe.112019.13.
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Lumpue Beach Subsurface Profile Analysis of Parepare City. This study aims to analyze the subsurface profile of Lumpue beach which is directly contaminated with activities around the coast. In this study, the Wenner Schlumberger method was used in the Lumpue beach area, Perepare City, South Sulawesi Province. The tool used is a multichannel geoelectric with a maximum length of 480 m in each trajectory, in this study there are 3 trajectories in which the first trajectory is 480 m with depth as deep as 91.2 m and the resistivity results obtained range from 0.207 -> 97.8 Ωm which identified as alluvium containing clay soil, silt soil, sandstone and pyroclastic rock bolder that has been contaminated by sea water. At lane 2 intersects the middle lane 1 with a length of 240 m and identified depths of 91.2 m, the recorded resistivity results range between 5.52 -> 623 Ωm where the resistivity value identifies the alluvium material, which contains clay, silt soil , sandstone that has been contaminated with water and the presence of some pyroclastic rock inserts that are contaminated by water. Whereas lane 3 intersects lane 1 at the end with a lenght of 240m and a depth of 91.2 m, while the recorded resistivity results range from 0.354 - 11776 Ωm where from the recorded resistivity results the material contained in lane 3 is the inserted alluvium material. by pyroclastic rocks. The area covered by the track is an area with alluvium material which is an alluvial unit and most of it is contaminated by water, either by sea water or fresh groundwater and is inserted by pyroclastic rocks.
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Yatsyshyn, Andriy, and Piotr Gębica. "STUDY OF THE HOLOCENE STAGE OF FORMATION OF THE DNIESTER VALLEY IN THE EASTERN CARPATHIAN FORELAND." PROBLEMS OF GEOMORPHOLOGY AND PALEOGEOGRAPHY OF THE UKRANIAN CARPATHIANS AND ADJACENT AREAS, no. 11(01) (December 2020): 118–39. http://dx.doi.org/10.30970/gpc.2020.1.3204.
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The article describes the main stages of studying of the floodplain and the first floodplain terrace of the Dniester river within the Eastern Carpathian Foreland fragment of the valley, and evaluates the results of existing studies. It is discovered that during all the stages of the research morphological and morphometric parameters of the floodplain and the first floodplain terrace of the Dniester river, morphology and facie structures of the alluvial accumulations, as well as palynological analyses of biogenic accumulations buried in an alluvial series are performed. The results obtained during the palynological analyzes are used to date the erosion-accumulation cycles and to reconstruct the physical-geographical conditions of the time of the floodplain and the first floodplain formation of the Dniester terrace. The radiocarbon dating of biogenic sediments buried in alluvial series is also actively conducted at the last stage of the research. The array of geological and geomorphological information collected at the first two stages of research made it possible to establish that, first, the first floodplain terrace and floodplain were formed during the Holocene in the Dniester Valley. The first floodplain terrace (the height of which reaches 4–6 m above the Dniester riverbed) can be considered as a high floodplain which is often covered by high floods. The terrace is accumulative, but unlike all other terraces of the Dniester it is devoid of the loess cover. In the cross-sections of its accumulations the deposits of the alluvium of the channel facies builted of pebbles are exposed and covered with the alluvium of the floodplain facies composed of sands, sandy loams and loams. The total thickness of alluvium reaches 9–10 m and it doesn’t varysignificantly downstream of the Dniester. Except the Upper Dniester basin, where the thickness of the alluvium increases to 10–18 m, and the layers of peat are found. The floodplain is 4–5 m above the Dniester riverbed and is built of alluvium of the channel facies, dominated by sand and pebble series. In someplaces floodplain is covered with sandy or loamy deposits of floodplain facies. Secondly, in the Eastern Carpathian Foreland part of the Dniester valley the course of fluvial morpholitogenetic processes was regulated not only by climatic changes and neotectonic movements, but also by human economic activity. During the XIX–XX centuries especially large-scale human influence was on the Dniester riverbeds by construction of flood ramparts, reclamation canals, etc. The results of recent geomorphological research conducted within the studied fragment of the river valley particularly palynological and radiocarbon dating have significantly improved the idea of morphology, structure and history of floodplain formation and the first floodplain terrace of the Dniester. The research revealed that the accumulation of alluvium of the first floodplain terrace which is above the Dniester riverbed reaches 5,5–6,5 (7) m and started to develop in the late Pleistocene (Bølling–Allerød interstadial) (13 000–11 000 years ago (GI–1)). Presumably in the early Dryas (11 000–10 000 years ago (GS–1)), the first floodplain terrace was dissected by the meandering channel of the Dniester. The alluvial deposits that fill these large paleomeanders are still well preserved and are often exposed in the ledges of the first terrace. The further development of the floodplain and first floodplain terrace of the Dniester river was taking place in several stages such as the end of the boreal, the beginning of the atlantic, the end of the atlantic, subboreal, the beginning of the subatlantic, as well as during V–VI, X–XII and XIV–XVI centuries. These stages are identified in correlation with the cycles of humidification of the climate and the growth of fluvial activity of riverbeds (flood phases). As a result of the intensification of erosion-accumulation activity of the Dniester the two – three levels of Holocene floodplain were formed up to 4–5 m and 3–4 m high. The first traces of human activity within the studied fragment of the Dniester valley were dated by subboreal and recorded by the presence of grain pollen in the spore-pollen diagrams of Mainych (Upper Dniester Basin) and Tsvitova (Galician-Bukachiv Basin) sections. Key words: Dniester valley; floodplain; the first floodplain terrace; alluvium; phases of floods; Allerød; early Dryas; Holocene.
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Zykin, V. S., V. S. Zykina, D. G. Malikov, L. G. Smolyaninova, and O. B. Kuzmina. "Lower–Middle Pleistocene Stratigraphy of the Southern West Siberian Plain: New Data." Russian Geology and Geophysics 62, no. 12 (December 1, 2021): 1359–72. http://dx.doi.org/10.2113/rgg20204218.
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Abstract —The Quaternary stratigraphy of the southern West Siberian Plain is considered in the context of the updated International Chronostratigraphic Scale, with the Neogene/Quarternary boundary at 2.588 Ma. New geological, lithological, paleontological, and paleomagnetic data from a reference Quaternary section in the Irtysh River valley near Isakovka Village provide more rigorous constraints on the Lower–Middle Pleistocene stratigraphy and the respective deposition conditions. The Isakovka outcrop exposes two stratigraphically expressed and paleontologically characterized units that were deposited during regional Pleistocene interglacial events of different ages: the Strunino and Serebryanoe alluvium beds lying over eroded surfaces. The species of the Corbicula genus coexisting with numerous species of Palearctic molluscs, small mammals Allophaiomys deucalion, Mimomys reidi, and last rooted lagurids Borsodia found in the Strunino alluvium are known also from continental equivalents of the warm upper Gelasian Stage in different parts of northern Eurasia. Judging by the presence of extant corbicules, the Strunino alluvium was deposited in a warm climate, with a mean annual air temperature above +16 °C and a mean winter temperature no colder than –8 °C, in rivers that remained free from ice all year round. On the basis of fauna constraints for the Serebryanoe alluvium, along with the first appearance of the European Pisidium clessini molluscs in West Siberia, the unit can be correlated with one of the earliest Middle Pleistocene interglacial events. The faunal assemblages and spore-pollen patterns of the two units indicate that the climate during the Serebryanoe deposition was slightly cooler and wetter than during the Strunino deposition, though steppe landscapes predominated on watersheds in both events. The two alluvial beds, which are traceable in river bluffs, at 30 m above the modern water level in a tectonically stable part of West Siberia, mark the hypsometrically higher position of the river network during the Early Pleistocene and early Middle Pleistocene interglacials.
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Grimaud, J. L., C. Paola, and V. Voller. "Experimental migration of knickpoints: influence of style of base-level fall and bed lithology." Earth Surface Dynamics 4, no. 1 (January 15, 2016): 11–23. http://dx.doi.org/10.5194/esurf-4-11-2016.
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Abstract. Knickpoints are fascinating and common geomorphic features whose dynamics influence the development of landscapes and source-to-sink systems – in particular the upstream propagation of erosion. Here, we study river profiles and associated knickpoints experimentally in a microflume filled with a cohesive substrate made of silica, water and kaolinite. We focus on the effect on knickpoint dynamics of varying the distribution of base-level fall (rate, increment, and period) and substrate strength, i.e., kaolinite content. Such simple cases are directly comparable to both bedrock and alluvial river systems. Under a constant rate of base-level fall, knickpoints of similar shape are periodically generated, highlighting self-organized dynamics in which steady forcing leads to multiple knickpoint events. Temporary shielding of the bed by alluvium controls the spacing between these unit knickpoints. Shielding is, however, not effective when base-level drops exceed alluvium thickness. While the base-level fall rate controls the overall slope of experiments, it is not instrumental in dictating the major characteristics of unit knickpoints. Instead the velocity, face slope and associated plunge pool depth of these knickpoints are all strongly influenced by lithology. The period between knickpoints is set by both alluvium thickness and base-level fall rate, allowing use of knickpoint spacing along rivers as an indicator of base-level fall rate.
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Grimaud, J. L., C. Paola, and V. Voller. "Experimental migration of knickpoints: influence of style of base-level fall and bed lithology." Earth Surface Dynamics Discussions 3, no. 3 (August 25, 2015): 773–805. http://dx.doi.org/10.5194/esurfd-3-773-2015.
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Abstract. Knickpoints are fascinating and common geomorphic features whose dynamics influences the development of landscapes and source-to-sink systems – in particular the upstream propagation of erosion. Here, we study river profiles and associated knickpoints experimentally in a micro flume filled with a cohesive substrate made of silica, water and kaolinite. We focus on the effect on knickpoint dynamics of varying the distribution of base-level fall (rate, increment, and period) and substrate strength, i.e. kaolinite content. Such simple cases are directly comparable to both bedrock and alluvial river systems. Under a constant rate of base-level fall, knickpoints of similar shape are periodically generated, highlighting a self-organized dynamics in which steady forcing leads to multiple knickpoint events. Temporary shielding of the bed by alluvium controls the spacing between these unit knickpoints. Shielding is however not effective when base-level drops exceed alluvium thickness. While the base-level fall rate controls the overall slope of experiments, it is not instrumental in dictating the major characteristics of unit knickpoints. Instead the velocity, face slope and associated plunge pool depth of these knickpoints are all strongly influenced by lithology. The period between knickpoints is set by both alluvium thickness and base-level fall rate, allowing use of knickpoint spacing along rivers as an indicator of base-level fall rate.
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Price, Audrey C., Edward W. Woolery, Ronald C. Counts, Roy B. Van Arsdale, Daniel Larsen, Shannon A. Mahan, and Ennis G. Beck. "Quaternary Displacement on the Joiner Ridge Fault, Eastern Arkansas." Seismological Research Letters 90, no. 6 (October 9, 2019): 2250–61. http://dx.doi.org/10.1785/0220190149.
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ABSTRACT The New Madrid seismic zone of the central United States is an intraplate seismic zone with blind structures that are not seismically active but may pose seismic hazards. The Joiner ridge fault (JRF) is the 35‐kilometer‐long east‐bounding fault of the Joiner ridge blind horst located in eastern Arkansas ∼50 km northwest of Memphis, Tennessee. Shallow S‐wave (SH‐mode) seismic reflection profiles, continuous cores, and radiometric dating of Quaternary alluvium across the JRF reveal down‐to‐the‐east reverse faulting and folding of Eocene strata and overlying Quaternary Mississippi River alluvium. The base of the Quaternary alluvium has an age of 20.3 ka and is vertically displaced 12 m, resulting in an average slip rate of 0.6±0.1 mm/yr over the past 20.3 ka. The overlying upper Wisconsinan and Holocene alluvial facies are also displaced by the JRF. These facies increase in thickness across the JRF and were used to calculate late Wisconsinan and Holocene slip histories. The JRF slipped 7 m between 20.3 and 17.5 ka, 3 m between 12.3 and 11.5 ka, and 2 m between 11.5 and 8.9 ka. No apparent slip occurred on the JRF within the last 8.9 ka. This research illustrates that slip has been intermittent and that slip magnitudes on the JRF diminished through the late Wisconsinan and early Holocene.
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Bowles, John F. W., Saioa Suárez, Hazel M. Prichard, and Peter C. Fisher. "The mineralogy, geochemistry and genesis of the alluvial platinum-group minerals of the Freetown Layered Complex, Sierra Leone." Mineralogical Magazine 82, S1 (February 28, 2018): S223—S246. http://dx.doi.org/10.1180/minmag.2017.081.032.
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ABSTRACTHeavy mineral concentrates from rivers and river terraces near York, Freetown Peninsula, Sierra Leone have been examined for their platinum-group mineral (PGM) content. The alluvial PGM are 0.1 to 1.5 mm in size and include Cu-bearing isoferroplatinum (Pt3Fe) and disordered Pt3–xFe (x≤ 0.38), tulameenite (Pt2FeCu), hongshiite (PtCu), cooperite–vysotskite (PtS–PdS), laurite (RuS2), erlichmanite (OsS2), Os-Ir alloy, Os-Ru alloy and native copper.Are the alluvial nuggets primary or a neoformation? Comparison of the PGM mineralogy of fresh rocks, weathered rocks and the saprolite, with the alluvial suite shows strongly contrasting features highlighted by the mineral assemblage. Cooperite in the fresh rocks is rare in the alluvium whilst Pt-Fe alloys become more abundant. Oxidized PGM are a feature only of the weathering process and disordering of the Pt-Fe alloys develops during weathering. Palladium is much less abundant in the alluvial suite than in the primary minerals whereas Cu, present as Cu-sulfides in the fresh rocks, occurs in the alluvium as a minor component of the Pt-Fe alloys and as hongshiite alteration to the Pt-Fe alloys. The size difference is striking; the primary mineralogy is micrometre-sized whereas the alluvial PGM are three orders of magnitude larger. Delicate PGM with alteration textures are seen only in the weathered rocks whilst delicate dendritic PGM are reported only from the alluvial suite. An organic coating to the alluvial PGM may be indicative of an organic or bacterial involvement. Some alluvial PGM occur in a drainage basin devoid of outcrops of PGE-bearing horizons.Together these contrasting features of the primary and placer PGM support the proposal that the Freetown nuggets developed as a result of breakdown of the primary PGM during weathering, movement of the PGE in solution, and growth of new PGM in placers with a different mineral assemblage, mineralogy and mineral chemistry.
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DeJong, J. T., A. P. Sturm, and M. Ghafghazi. "Characterization of gravelly alluvium." Soil Dynamics and Earthquake Engineering 91 (December 2016): 104–15. http://dx.doi.org/10.1016/j.soildyn.2016.09.032.
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Ganguly, J., and B. K. Banerjee. "Halloysite in Deltaic Alluvium." Transactions of the Indian Ceramic Society 45, no. 4 (January 1, 1986): 100. http://dx.doi.org/10.1080/0371750x.1986.10822799.
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Weston, D. G. "Alluvium and geophysical prospection." Archaeological Prospection 8, no. 4 (2001): 265–72. http://dx.doi.org/10.1002/arp.160.
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Somerville, M. R., H. Kagami, and K. F. McCue. "Seismic amplification determined from microtremor monitoring at alluvial and rock sites in Newcastle." Bulletin of the New Zealand Society for Earthquake Engineering 26, no. 2 (June 30, 1993): 175–84. http://dx.doi.org/10.5459/bnzsee.26.2.175-184.
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In the magnitude 5.6 Newcastle, N.S.W. earthquake of 28 December 1989, the area with highest seismic intensity (MM VIII) was located some 10 km from the epicentre. In the absence of local instrumental data for the event, various explanations of the intensity distribution have been advanced. A causative relationship has been suggested, with support from wave propagation calculations, in the close spatial correlation between the area with highest seismic intensity and the area with alluvial and/or fill cover. An alternative interpretation correlates intensity primarily with structural vulnerability rather than site geology. New evidence for amplified response of alluvial sites has been obtained from a microtremor monitoring experiment using 1-Hz seismometers.
Amplified response was observed at frequencies ranging from 1.5 Hz to 10 Hz, at sites with alluvial depth ranging from 40m to 5m. Most of these observations have a straightforward interpretation in terms of fundamental-mode (quarter-wavelength) resonance of the alluvium overlying a substratum of much greater rigidity. At some sites there is amplification but the quarter-wavelength resonance is not identifiable, due to a steep interface between the alluvium and the substratum, or perhaps the lack of a sharp rigidity contrast. The microtremor results, while useful for determining site resonance frequencies, are not expected to replicate the degree of amplification under strong earthquake excitation. The microtremor amplification factors are generally higher than the factor 3 ± 1 inferred from the seismic intensity distribution of the 28 December, 1989 earthquake.
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Hidayah, Risma Nur, Suhendra Suhendra, Halauddin Halauddin, Irkhos Irkhos, and Tela Dwi Syaputri. "Identification of liquefaction potential in Kampung Melayu Bengkulu based on water level depth (watertable)." Journal of Aceh Physics Society 13, no. 2 (May 6, 2024): 1–8. http://dx.doi.org/10.24815/jacps.v13i2.37089.
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Abstrak. Wilayah Kampung Melayu memiliki kondisi litologi batuan yang tersusun atas formasi undak alluvium (Qat) yang terdiri dari pasir, lempung, lanau, dan kerikil yang bersifat lepas sehingga dapat memicu terjadinya fenomena likuifaksi apabila terjadi gempa bumi. Penelitian ini bertujuan untuk mengetahui potensi likuifaksi berdasarkan nilai resisitivitas litologi batuan bawah permukaan bumi dan kedalaman muka air tanah (watertable) pada 40 titik Sounding di daerah penelitian dengan menggunakan metode Vertical Electrical Sounding (VES) konfigurasi Schlumberger. Hasil penelitian menunjukkan bahwa lapisan bawah permukaan di Kecamatan Kampung Melayu terdiri dari batuan alluvium, mencakup lempung, kerikil, pasir, napal, air payau, dan air tanah, dengan nilai resistivitas berkisar antara 0 hingga 508 Ω.m. Keberadaan formasi alluvium ini menjadi ancaman yang serius pada saat terjadi gempa bumi yang dapat bepotensi terjadinya likuifaksi. Kedalaman muka air tanah (watertable) di wilayah ini relatif dangkal, berkisar antara 1 hingga 25 meter, dengan nilai resistivitas antara 5,1 hingga 40 Ω.m. Adanya zona jenuh air yang dangkal dan struktur batuan alluvium menunjukkan potensi resiko likuifaksi. Abstract. The Kampung Melayu area has rock lithology conditions which are composed of alluvium step formations (Qat) consisting of loose sand, clay, silt and gravel which can trigger liquefaction phenomena when an earthquake occurs. This research aims to determine the liquefaction potential based on the lithological resistivity values of the earth's subsurface rocks and the depth of the groundwater table (watertable) at 40 sounding points in the research area using the Schlumberger configuration Vertical Electrical Sounding (VES) method. The research results show that the subsurface layer in Kampung Melayu District consists of alluvium rock, including clay, gravel, sand, marl, brackish water and groundwater, with resistivity values ranging from 0 to 508 Ω.m. The existence of this alluvium formation poses a serious threat during an earthquake which could potentially cause liquefaction. The depth of the groundwater table (water table) in this area is relatively shallow, ranging from 1 to 25 meters, with resistivity values between 5.1 and 40 Ω.m. The existence of shallow water saturated zones and alluvium rock structures indicate a potential risk of liquefaction.
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McMahon, William J., and Neil S. Davies. "Physical and biological functioning in Proterozoic rivers: evidence from the archetypal pre-vegetation alluvium of the Torridon Group, NW Scotland." Scottish Journal of Geology 56, no. 1 (October 11, 2019): 1–29. http://dx.doi.org/10.1144/sjg2019-013.
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In modern rivers, vegetation affects hydrological, geomorphological and sedimentological functioning, so extant fluvial systems can provide only partial analogues for those rivers that operated before the evolution of land plants. However, pre-vegetation rivers were the norm for the first 90% of Earth's history and so a better understanding of their sedimentary product can provide insights into both the fundamental underlying mechanisms of river behaviour and the ways in which fluvial processes operated on ancient Earth. In addition to a short review of the history of research into pre-vegetation alluvium, this paper presents a fieldwork-based case study of the later Proterozoic Torridon Group, which contains some of the most extensive and easily accessible exposures of pre-vegetation alluvium worldwide. Three alluvial architectural deposits have been recognized: (1) channel-bedform deposits (c. 80%); (2) barform deposits (c. 20%); and (3) out-of-channel deposits (≪1%). Channel-bedform deposits have erosional bases and most frequently stack vertically to form thick multistorey channel-bedform sequences. The preferential preservation of these deposits, which record the deepest parts of river channels, suggests that channel migration had a dominant control on preservation in the Torridon Group. Less frequently, channel-bedform deposits pass upwards into a genetically related barform deposit. Barform preservation in these instances is interpreted to be due to channel avulsion, which protected the barforms from reworking. Channel-bar thickness, measured from the basal erosional surface of a channel-bedform deposit to the top of its associated barform deposit, indicates minimum water depths of 1.7 to 8.0 m. Downstream-accreting barform deposits are most frequent, but lateral and upstream modes of accretion are also well represented. Dominant southeastward-palaeoflow directions imply that the Torridonian rivers were sourced from the Grenvillian Mountain Belt. The preserved architectural deposits and narrow dispersal of palaeocurrent data are explained by interpreting the Torridon Group as the alluvium of dominantly low-sinuosity rivers, with signatures recording autogenic fluvial adjustments. In the few rare instances where out-of-channel deposits are preserved, they contain fossil evidence for microbial mats, which prove that not all Proterozoic river systems were wholly abiotic. The overall characteristics of the Torridon alluvium, in terms of its ubiquitous highly tabular beds of sand-grade or coarser material, make it an archetypal example of pre-vegetation alluvium as known globally.Thematic collection: This article is part of the SJG Collection on Early-Career Research available at: https://www.lyellcollection.org/cc/SJG-early-career-research
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Hall, Stephen A. "Late Quaternary fluvial environments at Abo Arroyo, New Mexico, U.S.A.: response to millennial-scale climate change." Journal of Sedimentary Research 93, no. 6 (June 30, 2023): 413–29. http://dx.doi.org/10.2110/jsr.2022.099.
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ABSTRACT Abo Arroyo is a tributary of the Rio Grande in central New Mexico. Its alluvial sequence is made up of four informal units, their age defined by 44 AMS radiocarbon dates from 12.8 ka to 0.85 ka. The earliest, unit 1, is terminal Pleistocene to early Holocene (12.8 ka to 9.0 ka), including the Scholle wet meadow (12.3 ka to 11.1 ka) related to the Younger Dryas. After an erosional gap in the record from 9 ka to 6 ka, coarse gravel (unit 2) was deposited in the channel (5.8 ka and 4.3 ka) during the middle Holocene period of aridity. Subsequently, the late Holocene wet period is characterized by fine-textured alluvium (unit 3) (3.5 ka to 0.945 ka) with shells of an aquatic snail, indicating persistent stream flow. An upper 2-m zone of dark-colored clayey silt beds with high amounts of organic carbon and carbonate accumulated from 1.7 ka to 0.945 ka. A record of C4 signatures, previously interpreted to indicate dry conditions 1.4 ka to 0.945 ka, is reinterpreted as an interval of exceptionally wet floodplain conditions with C4 grasses and sedges. Abo Arroyo and other studies indicate three major episodes of late-Quaternary channel entrenchment: 1) from the full-glacial to late glacial-Bølling/Allerød (6.1 ky), 2) during the middle Holocene (2.5 ky), and 3) during the late Holocene Medieval Warm Period (0.4 ky), each erosional event less severe and shorter duration than the preceding one, and all three represent a significant change from wet to dry climate. During the Medieval Warm Period (A.D. 900 to 1300), a shallow channel formed in unit 3 alluvium, bracketed by AMS dates A.D. 1005 in unit 3 alluvium and A. D. 1100 in unit 4 channel fill. The channel cutting occurred with the shift from wet to dry climate, although the downcutting event was preceded by 100 years of landscape adjustment to the long drought. The canyon fill was entrenched again, deep and wide, by arroyo cutting in the late nineteenth and early twentieth centuries. The regional 83-year second-century drought (A.D. 100 to A.D. 182), documented by tree rings, shows up in the stable-carbon-isotope record from Abo Arroyo alluvium. The drought was more severe than the 400-year warm period but had little effect on the preserved alluvial record. The less severe but longer-duration Medieval Warm Period resulted in channel cutting at Abo Arroyo and elsewhere in the broad region at that time, but the second-century drought did not. Finally, the similarity of Abo Arroyo and Rio Grande late Holocene alluvial records with parallel stratigraphy, sedimentology, and geochronology illustrates that tributaries and main valleys respond alike and in concert to climate and climate change.
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Morgunov, K. P., Yu K. Ivanovsky, and V. G. Bogatyrev. "Laboratory studies of the soil erosion and alluvium processes in the area of bridge supports." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 15, no. 6 (February 6, 2024): 971–86. http://dx.doi.org/10.21821/2309-5180-2023-15-6-971-986.
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The results of experimental studies of the process of bottom erosion during the construction of bridge supports under the protection of a sheet pile structure are presented. To protect the sheet piling box from the influence of ice floes during the period of ice drift, it is planned to install an ice-cutting protective device located upstream of the sheet piling box. In the process of conducting research, the principles of modeling the processes of river sediment transport taking into account the size of transported particles, non-erosive velocities and channel slopes are substantiated. Laboratory studies of the processes of forming erosion and alluvium are carried out for two cycles of parameters. At the same time, the influence of the ice-cutting device position relative to the sheet piling box on the amount of erosion and alluvium is studied. Experiments were carried out for various options of the ice cutter position relative to the sheet piling box; the ice cutter moved upstream along the axis of the tray with a step of 0.1 m (5 m for natural conditions). Based on measurements of bottom surface marks, two-dimensional erosion plans are constructed. For several options for the location of structures, the trajectories and directions of flow movement are determined by photographing the movement of surface floats, which makes it possible to create a grid of streamlines and determine the values of surface current velocities. An analysis of the velocity distribution over the surface and in the flow volume has shown that a horseshoe-shaped vortex is formed around the structure, with riffles and ridges appearing along its wings. A stagnation zone is established inside the “horseshoe”; in this zone the bottom remains relatively smooth. In the absence of an ice cutter, the main zones of soil erosion arise in the vicinity of the corners of the front face of the box, and alluviums form in the rear part of the structure. When installing an ice-cutting device in the shape of a triangle in front of the box, directed at an acute angle towards the oncoming flow, the erosion zones move to the vicinity of the corners lying at the base of the triangular ice cutter facing the box. The absolute values of erosion depth and alluvium height are reduced compared to the option without the ice cutter. When the ice cutter moves upstream relative to the box, a washout zone appears in the gap between the ice cutter and the box. The maximum values of erosion and alluvium occur in the absence of ice cutter and when placing the ice cutter at a distance of 200–300 mm from the box. The minimum values of erosion and alluvium are recorded when the ice cutter is placed close to the support box. With increasing flow rates and depths, the values of erosion and alluvium increase. Installing the ice-cutting device improves the hydraulic conditions of flow around the sheet piling box structure, which leads to a decrease in washout depths.