Sediment Instability Research Articles

Dynamic fracture and wave propagation in a granular medium: A photoelastic study

In our earlier work on the generation mechanisms of earthquakes and related failures, fracture phenomena were treated in the framework of continuum mechanics, and the existence of the universal critical condition for earthquake nucleation as well as the strong dependence of earthquake-induced structural failure patterns on the frequencies and types of incident seismic waves was pointed out. However, other significant seismic phenomena such as landslides and liquefaction may not be simply explained using the theories established for continuum media. For example, in order to clarify the physics of the formation of the geological flame structure, possibly due to liquefaction and ensuing gravitational instability in water-immersed sediments, the mechanical behavior of particles under dynamic load and the influence of waves, if any, on fracture should be understood for granular media beforehand. Here, as an initial investigation into wave and fracture propagation inside granular media, under dry conditions first of all, experimental technique of dynamic photoelasticity is employed. Penny-shaped particles made of birefringent polycarbonate are prepared and placed on a rigid horizontal plane to form two-dimensional model slopes with certain inclination angles. Dynamic impact is given to the top (approximately) horizontal free surface of the slope, and the transient evolution of stress and fracture is recorded by a high-speed digital video camera. It is shown that depending on the profile of energy imparted by the impact, (i) one-dimensional force-chain-like stress transfer or (ii) widely spread multi-dimensional wave propagation can be found. While the case (i) results in mass flow, i.e. total collapse of the slope, in (ii) waves can induce dynamic separation of only slope faces similar to toppling failure. The experimentally observed wave and fracture phenomena in granular media are compared to those in continuum media and the actual slope failure repeatedly caused in Japan, New Zealand and USA.

Environmental forcing of intertidal benthic macrofauna of Bodo Creek, Nigeria: Preliminary index to evaluate cleanup of Ogoniland

Pristine and before-disturbance baseline data are essential tools in monitoring and measurement of progress and net success or otherwise of restoration of degraded ecosystems. These are usually lacking in regions such as the Niger Delta where demands for such data is pressing due to impending pollution. We present a rare case of available pre-spill data of how distribution and abundance of macrobenthic infauna were structured by some physical and chemical variables of interstitial water in Bodo Creek, lower eastern Niger Delta, Nigeria, before two major oil spills impacted the creek in 2008. Monthly composite samples of macrobenthos and interstitial water in four soft-bottom unvegetated intertidal flats were analysed for one year. Thirty six taxa, twenty-two families and four classes of macrozoobenthos were recorded. The bivalves Lorepis aberrans, Macoma innominata, Senilia senilis, and polychaetes Nereis diversicolor, N. virens, N. pelagic and Clymenella torquata were eurizonal in distribution and abundant, attaining sub-dominant and dominant status at the sites. The observed pattern of reduction in rainy season macrofauna abundance in some river systems of the Niger Delta due to sediment instability was counterbalanced by increased recruitment of the dominant taxa. Canonical Correspondence Analysis (CCA) showed the explanatory (physicochemical) variables only accounted for 31.8% of variation in the species data. The species–environmental correlations were: 0.64, 0.74 and 0.72 for the first, second and third axes, respectively. Plans for cleanup, remediation and ‘restoration’ of Bodo Creek, have reached implementation stage as the Federal Government of Nigeria flagged off cleanup of Ogoniland on June 2, 2016. The usefulness of these data as potential template for monitoring and evaluation of water quality response to the proposed cleanup and restoration is highlighted.

Timing and controls on the delivery of coarse sediment to deltas and submarine fans on a formerly glaciated coast and shelf

The evolution of deltas and submarine fans is often envisioned as largely controlled by relative sea-level variations. However, in some cases, relative sea level can have less effect on delta and submarine fan activity than sediment supply and shelf geomorphology. In order to document the relative importance of these three factors on deltaic and submarine fan evolution in a formerly glaciated environment, this paper documents the delivery of coarse sediment to the Laurentian Channel (eastern Canada). The well-constrained stratigraphic and geomorphologic framework of both the glacio-isostatically uplifted deltas and the modern Laurentian Channel fans allows us to document and contrast the evolution of river-fed deltas, river-fed canyon/fan systems, and longshore drift–fed fans during deglacial and postglacial times. The evolution of these different types of fans can be divided into three phases. The first phase was characterized by delta progradation on the shelf while relative sea level was at its maximum, although already falling, and the ice margin gradually retreated inland. The second phase was characterized by the delivery of deltaic sediment in the deep realm of the Laurentian Channel, permitted by the supply of large amounts of glaciogenic sediments derived from the retreating ice margin and the lowering of the relative sea level. At the same time, sediment instability along the steep Laurentian Channel formed small incisions that evolved into submarine canyons where the narrow shelf allowed the trapping of longshore sediment. The third phase was characterized by the withdrawal of the ice margin from the watershed of the main rivers and the drastic decrease in sediment supply to the deltas. Consequently, the delta fronts experienced strong coastal erosion, even though relative sea level was still lowering in some cases, and the eroded sediments were transferred onto the shelf and to adjacent bays. This transfer of coastal sediments allowed the continued activity of longshore drift–fed canyons. The retreat of the ice margin from the watersheds thus controlled the supply of sediment and induced a change in delta type, passing from river-dominated to wave-dominated deltas. This paper highlights the role of the type of sediment supply (ice-contact, glaciofluvial, and longshore drift) in the timing and activity of submarine fans in high-latitude environments. A conceptual model is proposed for high-latitude shelves where sediment delivery to submarine fans is mostly controlled by structural inheritance (watershed area and shelf geomorphology) rather than relative sea-level fluctuations. Therefore, although relative sea level fell during delta progradation, this study demonstrates that it was not the main contributor to delta and submarine fan growth. This has wider implications for the extraction of sea-level information from stratigraphic successions.

The Gebra–Magia Complex: mass-transport processes reworking trough-mouth fans in the Central Bransfield Basin (Antarctica)

Abstract The Gebra–Magia Complex is an important example of a submarine mass-movement composite located on the lower continental slope of the Antarctic Peninsula (Central Bransfield Basin). Continuous instability dynamics over time is inferred to have affected the palaeo-trough-mouth fans present in the study area. The depositional architecture and the outstanding relief of the Gebra Valley, which is the most striking morphological feature in the area, determine the asymmetrical morphology of the complex. This complex is characterized, from east to west, by an open-slope margin flanking the sidewall of the Gebra Valley, the Gebra Valley itself and a SW margin that is connected to the Magia area by a large scar approximately 7.8 km to the SW. The Gebra Valley is a Quaternary debris valley resulting from repeated large-scale mass-transport and cut-and-fill processes. In contrast, the Magia area is dominated by unchannelized sedimentary instability processes, resulting in a different sedimentary architecture and morphology. The near-surface sediments in the Gebra–Magia Complex document the continuous occurrence of recent mass movements, as also evidenced by flows transported downslope as unchannelized or channelized flows. Climate and tectonic activity are considered the primary factors controlling the development of the complex.

Anhydrous reverse micelle nanoparticles: new strategy to overcome sedimentation instability of peptide-containing pressurized metered-dose inhalers

The objective of this study was to develop a novel anhydrous reverse micelle nanoparticles (ARM-NPs) system to overcome the sedimentation instability of peptide-containing pressurized metered-dose inhalers (pMDIs). A bottom-up method was utilized to fabricate ARM-NPs. Tertiary butyl alcohol (TBA)/water system, freeze-drying and lipid inversion method were successively used to produce the ARM-NPs for pMDI. Various characteristics of ARM-NPs were investigated including particle size, morphology, secondary structure of the peptide drug, aerosolization properties and storage stability. As revealed by the results, ARM-NPs with spherical shape possessed 147.7 ± 2.0 nm of particle size with 0.152 ± 0.021 PdI. The ARM-NPs for pMDI had satisfactory fine particle fraction (FPF) value of 46.99 ± 1.33%, while the secondary structure of the peptide drug was unchanged. Stability tests showed no pronounced sedimentation instability for over 12 weeks at 4–6 °C. Furthermore, a hypothesis was raised to explain the formation mechanism of ARM-NPs, which was verified by the differential scanning calorimetry analysis. The lecithin employed in the reverse micelle vesicles could serve as a steric barrier between peptide drugs and bulk propellant, which prevented the instability of peptide drugs in hydrophobic environment. Homogenous particle size could avoid Ostwald ripening phenomenon of particles in pMDIs. It was concluded that the ARM-NPs for pMDI could successfully overcome sedimentation instability by the steric barrier effect and homogeneous particle size.

Evidence and age estimation of mass wasting at the distal lobe of the Congo deep-sea fan

On continental margins, sulfate reduction occurs within the sedimentary column. It is coupled with the degradation of organic matter and the anaerobic oxidation of methane. These processes may be significantly disturbed by sedimentary events, leading to transient state profiles for the involved chemical species. Yet, little is known about the impact of turbidity currents and mass wasting on the migration of chemical species and the redox reactions in which they are involved. Due to its connection to the River, the Congo deep-sea fan continuously receives huge amount of organic matter-rich sediments primarily transported by turbidity currents, which impact on the development of the associated ecosystems (Rabouille et al., 2017). Thus, it is well suited to better understand causal relationships between sedimentary events and fluid flow path, with consequences on the zonation of early diagenesis sequences.Here, we combined sedimentological observations with geochemical analyses of pore-water and sediment samples to explore how sedimentary instabilities affected the migration of methane and the distribution of organic matter within the sedimentary column. The results unveiled mass wasting processes affecting recent turbiditic and pelagic deposits, and are interpreted as being slides/ slumps and debrites. Two slides were responsible for the exhumation of an organic matter-rich sedimentary block of more than 5m thick and the movement of a methane-rich sedimentary block, while turbidity currents enable the intercalation of sandy intervals within a pelagic clay layer. The youngest slide promoted the development of two Sulfate Methane Transition Zones (SMTZ), and may have possibly triggered a lateral migration of methane. Numerical simulation of the sulfate profile indicates that the youngest sedimentary event has occurred around a century ago. Our study emphasizes that turbidity currents and sedimentary instabilities can significantly affect the transport paths and the distribution of both methane and organic matter in the terminal lobe complex, with consequences on geochemical zonation of the sequential early diagenetic processes within the sedimentary column.

Sedimentation and potential venting on the rifted continental margin of Dronning Maud Land

The relief of Dronning Maud Land (DML), formed by Middle and Late Mesozoic tectonic activity, had a strong spatial control on the early fluvial and subsequent glacial erosion and deposition. The sources, processes, and products of sedimentation along the DML margin and in the Lazarev Sea in front of the DML mountains have been barely studied. The onshore mountain belt parallel to the coast of the DML margin acts as a barrier to the transport of terrigenous sediments from the east Antarctic interior to the margin and into the Lazarev Sea. Only the Jutul–Penck Graben system allows a localized ice stream controlled transport of material from the interior of DML across its old mountain belt. Offshore, we attribute repeated large-scale debris flow deposits to instability of sediments deposited locally on the steep gradient of the DML margin by high sediment flux. Two types of canyons are defined based on their axial dimensions and originated from turbidity currents and slope failures during glacial/fluvial transport. For the first time, we report pipe-like seismic structures in this region and suggest that they occurred as consequences of volcanic processes. Sedimentary processes on the DML margin were studied using seismic reflection data and we restricted the seismic interpretation to the identification of major seismic sequences and their basal unconformities.

Scavenger and burrowing features of Hippa pacifica (Dana 1852) on a range of tropical sandy beaches

Carrion consumption and scavenging are increasingly recognized for their role in community structure and food web dynamics The Pacific mole crab Hippa pacifica (Dana 1852) is a conspicuous scavenger of the swash zone of exposed sandy beaches on islands of the Pacific and Indo-Pacific regions. Our findings on the population structure of this species on Hawaiian beaches differed with the method of sampling used (baited vs. non-baited). The rapid attraction and aggregation of large crabs to bait stations contrasted with the population samples dominated by small crabs collected in the absence of bait. This result suggested that small individuals were excluded by larger crabs when competing for carrion resources. Burrowing velocity (mm s−1) increased with increasing carapace length, meaning that large individuals were more efficient than small crabs in the harsh hydrodynamic environment of the swash. Burrowing assays to exhaustion in laboratory conditions indicated that the ability of the crabs to cope with the harsh environment of the swash zone is a body size-dependent feature, independent of sex or fecundity state. We simulated the potential effect of the hydrodynamic and sediment instability typical of the swash zone of reflective beaches with a consecutive sequence of removals from the sediment. Following this treatment, the burrowing times of the larger crabs were shorter than those of the small individuals. Crab abundance was not related to sand grain size or to beach morphodynamics. Abundance was correlated with the amount of edible organic matter in the sediments, suggesting that H. pacifica is a highly opportunistic species, able to feed on a wider range of potential food sources than expected.

A giant, submarine creep zone as a precursor of large-scale slope instability offshore the Dongsha Islands (South China Sea)

A giant submarine creep zone exceeding 800 km2 on the continental slope offshore the Dongsha Islands, South China Sea, is investigated using bathymetric and 3D seismic data tied to borehole information. The submarine creep zone is identified as a wide area of seafloor undulations with ridges and troughs. The troughs form NW- and WNW-trending elongated depressions separating distinct seafloor ridges, which are parallel or sub-parallel to the continental slope. The troughs are 0.8–4.7 km-long and 0.4 to 2.1 km-wide. The ridges have wavelengths of 1–4 km and vertical relief of 10–30 m. Slope strata are characterised by the presence of vertically stacked ridges and troughs at different stratigraphic depths, but remaining relatively stationary in their position. The interpreted ridges and troughs are associated with large-scale submarine creep, and the troughs can be divided into three types based on their different internal characters and formation processes. The large-scale listric faults trending downslope below MTD 1 and horizon T0 may be the potential glide planes for the submarine creep movement. High sedimentation rates, local fault activity and the frequent earthquakes recorded on the margin are considered as the main factors controlling the formation of this giant submarine creep zone. Our results are important to the understanding of sediment instability on continental slopes as: a) the interpreted submarine creep is young, or even active at present, and b) areas of creeping may evolve into large-scale slope instabilities, as recorded by similar large-scale events in the past.

Current surges and seabed erosion near the shelf break in the Canadian Beaufort Sea: A response to wind and ice motion stress

Estimating the erosion potential of seabed sediments and the magnitude of the resulting suspended load in relation to current dynamics near the shelf break is a key issue for better understanding shelf-slope sediment transport. On the outer Mackenzie Shelf (Canadian Beaufort Sea, Arctic Ocean), a thin and discontinuous veneer of recent surficial clays overlie old glaciomarine sediments that further pinch out at the shelf edge. Gas and fluid venting is known to underlie part of sediment instability in the area, but recent mooring-based measurements also indicate that sediments near the shelf break are recurrently remobilized by strong subsurface currents. Here, we relate storms to the development of current surges that resulted in the abrupt resuspension of sediments at two locations along the shelf break. Near-bottom concentrations of suspended sediments were estimated using the acoustic backscatter of high-frequency acoustic Doppler current profilers deployed from September 2011 to September 2013 as part of the Beaufort Regional Environmental Assessment (BREA) program. Near-bottom currents near the shelf edge (140 to 150 m isobaths) were characterized by recurring episodes of elevated velocities (instantaneous speeds up to ~40-50 cm s-1) that were extensions of current surges (~60-80 cm s-1) occurring in the core of the shelfbreak jet located at ca. 90-120 m. Sudden peaks in suspended sediments (above 100 g m-3) corresponded closely with current surges in the near-bottom boundary layer (<10 m) implying the local erosion of surficial sediments and the rapid advection or redeposition of the resuspended sediments. A range of apparent threshold velocities from 18 to 36 cm s-1 was calculated based on the relationship between suspended sediment concentrations and near-bottom current speeds. Two meteorological scenarios were identified to explain the current surges underlying these erosion events at the shelf edge: (1) Pacific or Arctic-born low pressure systems that propagate into the southern Beaufort Sea and are associated with intense downwelling-favorable westerly winds. These amplify the eastward-setting shelfbreak jet along the upper slope, such as in September 2012 when successive cyclones developed during the record-low sea ice extent. (2) The persistence of a high-pressure system over the Beaufort Sea that causes strong upwelling-favorable easterly winds and a strengthening of anti-cyclonic ice motion. This induces a reversal of the shelfbreak jet to the west and a subsequent eastward-directed relaxation flow when the winds fade, such as during the major ice fracturing events of January to March 2013 that were associated with strong and persistent current speeds.

Tectonic activity evolution of the Scotia‐Antarctic Plate boundary from mass transport deposit analysis

AbstractThe spatial distribution and temporal occurrence of mass transport deposits (MTDs) in the sedimentary infill of basins and submerged banks near the Scotia‐Antarctic plate boundary allowed us to decode the evolution of the tectonic activity of the relevant structures in the region from the Oligocene to present day. The 1020 MTDs identified in the available data set of multichannel seismic reflection profiles in the region are subdivided according to the geographic and chronological distributions of these features. Their spatial distribution reveals a preferential location along the eastern margins of the eastern basins. This reflects local deformation due to the evolution of the Scotia‐Antarctic transcurrent plate boundary and the impact of oceanic spreading along the East Scotia Ridge (ESR). The vertical distribution of the MTDs in the sedimentary record evidences intensified regional tectonic deformation from the middle Miocene to Quaternary. Intensified deformation started at about 15 Ma, when the ESR progressively replaces the West Scotia Ridge (WSR) as the main oceanic spreading center in the Scotia Sea. Coevally with the WSR demise at about 6.5 Ma, increased spreading rates of the ESR and numerous MTDs were formed. The high frequency of MTDs during the Pliocene, mainly along the western basins, is also related to greater tectonic activity due to uplift of the Shackleton Fracture Zone by tectonic inversion and extinction of the Antarctic‐Phoenix Ridge and involved changes at late Pliocene. The presence of MTDs in the southern Scotia Sea basins is a relevant indicator of the interplay between sedimentary instability and regional tectonics.

Biodiversity and life strategies of deep-sea meiofauna and nematode assemblages in the Whittard Canyon (Celtic margin, NE Atlantic Ocean)

An extensive sampling strategy has been carried out along bathymetric transects in two branches (Eastern middle and Western) of the Whittard Canyon and in two adjacent open slopes to investigate meiofaunal assemblages (including nematode diversity and their life strategy) in the Celtic margin, Northern Gulf of Biscay. Our results show the presence of differences in terms of meiofaunal abundance and biomass among habitats even when located at the same depth. Meiofaunal abundance and biomass in the upper and middle (1000–2000m) part of the branches of the Whittard Canyon are typically higher than those reported in adjacent open slopes while, in deeper sediments (ca. 3000m), an opposite pattern is detected. The availability of food sources (both in term of quantity and quality) plays a key role in explaining such differences. Diversity expressed either as the richness of meiofaunal taxa and of nematode species is typically higher in slopes than in the branches of the Whittard Canyon. Turnover diversity is high (40–100% for meiofaunal rare taxa and 61–78% for nematode species, respectively) either among habitats and depths. Although a general dominance of deposit feeders, predators are more abundant in slopes (9–12% of total nematode abundance) than in both branches of the Whittard Canyon (4–7%). The higher fraction of predators of the nematode assemblages inhabiting the slopes determined higher values of the maturity index (i.e., more persisters, c-p=4/5). We hypothesize that the life strategies of nematode assemblages are influenced by gravity flows, sediment instability and the 2–3 times higher availability of phytopigments, which characterize the upper part of the Whittard Canyon, favoring opportunist/colonizer species. Our findings indicate that different deep-sea habitats are associated to different life strategies, thus contributing to increase the functional diversity of deep-sea ecosystems.

Different frequencies and triggers of canyon filling and flushing events in Nazaré Canyon, offshore Portugal

Submarine canyons are one of the most important pathways for sediment transport into ocean basins. For this reason, understanding canyon architecture and sedimentary processes has importance for sediment budgets, carbon cycling, and geohazard assessment. Despite increasing knowledge of turbidity current triggers, the down-canyon variability in turbidity current frequency within most canyon systems is not well constrained. New AMS radiocarbon chronologies from canyon sediment cores illustrate significant variability in turbidity current frequency within Nazaré Canyon through time. Generalised linear models and Cox proportional hazards models indicate a strong influence of global sea level on the frequency of turbidity currents that fill the canyon. Radiocarbon ages from basin sediment cores indicate that larger, canyon-flushing turbidity currents reaching the Iberian Abyssal Plain have a significantly longer average recurrence interval than turbidity currents that fill the canyon. The recurrence intervals of these canyon-flushing turbidity currents also appear to be unaffected by long-term changes in global sea level. Furthermore, canyon-flushing and canyon-filling have very different statistical distributions of recurrence intervals. This indicates that the factors triggering, and thus controlling the frequency of canyon-flushing and canyon-filling events are very different. Canyon-filling appears to be predominantly triggered by sediment instability during sea level lowstand, and by storm and nepheloid transport during the present day highstand. Canyon-flushing exhibits time-independent behaviour. This indicates that a temporally random process, signal shredding, or summation of non-random processes that cannot be discerned from a random signal, are triggering canyon flushing events.

Lithification facilitates frictional instability in argillaceous subduction zone sediments

Previous work suggests that in subduction zones, the onset of large earthquake nucleation at depths>~5–10km is likely driven by a combination of factors associated with the process of lithification. At these depths, lithification processes affect the entire fault system by modifying the mechanical properties of both the plate boundary fault zone and the wall-rock. To test the hypothesis that lithification of subduction zone sediments produces rocks capable of earthquake nucleation via diagenesis and low-grade metamorphism, we conducted friction experiments on fossil subduction zone sediments recovered from exposures in the Shimanto Belt in SW Japan. These meta-sediments represent accreted and subducted material which has experienced maximum temperatures of 125 to 225°C, which are representative of seismogenic depths along the active Nankai subduction megathrust in the foreland of the Shimanto Belt. We find that intact Shimanto rock samples, which preserve the influence of diagenetic and metamorphic processes, exhibit the potential for unstable slip under in-situ pressure conditions. Powdered versions of the same samples tested under the same conditions exhibit only velocity-strengthening friction, thus demonstrating that destroying the lithification state also removes the potential for unstable slip. Using advanced porosity loss to quantify the lithification process, we demonstrate that increased velocity weakening correlates with increasingly advanced lithification. In combination with documented frictionally stable behavior of subduction zone sediments from shallower depths, our results provide evidence that the sediment lithification hypothesis can explain the depth-dependent onset of large earthquake nucleation along subduction zone megathrusts.

Structure and functional characteristics of the meiofauna community in highly unstable intertidal mudbanks in Suriname and French Guiana (North Atlantic coast of South America)

The North Atlantic coast of South America is influenced by the Amazon River. This coast is considered the muddiest in the world due to the enormous suspended sediment input from the Amazon River. The mobility of the sediment imposes a geomorphological dynamic with a rapid change of shoreline and fast alternation of facies types of the sediment. This study first describes the spatial and functional structure of meiofauna communities of highly unstable intertidal flats along coasts of French Guiana and Suriname in relation to environmental variables. Six sampling sites, composed mainly of muddy sediment, were located 700km (Kourou) to 1200km (Nickerie) from the mouth of the Amazon River. The granulometry, chlorophyll a biomass, prokaryote abundance, percentage of organic matter, meiofauna abundance and feeding guilds of nematodes in sediment stations were independent of the distance of the Amazon River mouth and likely were more influenced by the local dynamism of migration of mudbanks. Meiofauna was not more abundant when the sediment was dominated by the finest sediment particles and also when chlorophyll a and prokaryotes, potential prey of meiofauna, were greater. However, as a percentage, small nematodes (biomass of 0.07±0.001µgind−1), which are mainly epigrowth-feeders, were more abundant in very fluid mud. Local granulometry and organic matter content appeared to be driving factors of the size structure and functional characteristics of nematodes. Despite the high instability of mudflats, chlorophyll a biomass and meiofauna abundance always tended to be higher toward other world areas. No foraminifera among the six stations of the study were found. Very fluid mud with physical instability of sediment caused a large perturbation to the settlement of meiofauna; the least amounts of chlorophyll a biomass and prokaryotic and meiofauna abundances were found there. Thus, the probable mobility of sediment may select for smaller meiobenthic organisms, mainly epigrowth-feeders nematodes, and disturb the larger organisms in the sediment, and, therefore, they would not permit the settlement of the foraminifera. In addition, no non-permanent meiofauna largely was found in the sediment.

TECHNOLOGICAL SUPPLEMENTARY MEANS FOR IMPROVEMENT OF BEVERAGE TECHNOLOGY

Abstract: Processing of raw materials, semi-finished and finished products with the help of a variety of aids is one of the most urgent methods of solving the problem of increasing beverage storage duration. The paper shows the state of a beverage as a disperse system during the process. In the semi-finished products at the beginning of technological chain the process of diffusion is not determined, thus the system of beverages experiences sedimentary instability. The processing of semi-finished and finished beverages before pre-packaging by various technological supplementary means leads to the formation of sedimentary stability, in which a sedimentation - diffusion equilibrium takes place. The hypothetical model of the state of beverage disperse system under the influence of technological supplementary means is demonstrated. Disperse system of beverages can be exposed in three main positions: sedimentary unstable, stable (equilibrium), excessively stable. The brief overview of characteristic features of supplementary means is presented, the latter being used in beverage technology to ensure the stability of products with the help of research data presented by domestic and foreign authors. One of the variants of classification of processing aids is the usage of hierarchical method. Structural and technological characteristics of the subsidiary materials used for durability of beverage upon storage are presented as a classification basis. Signs and stages of classification are marked. The presented embodiment of classification methodology can serve as a basis for the selection of processing with the help of supplementary methods, based on individual characteristics of the structural properties of complex means and substances involved in turbidity formation, as well as for indication of the parameters of materials rational usage in the production line as one of the fundamental factors for the formation of finished products quality.

Late Cretaceous–Miocene sedimentary development of the Arabian continental margin in SE Turkey (Adıyaman region): Implications for regional palaeogeography and the closure history of Southern Neotethys

The Middle Cretaceous–Late Miocene sedimentary successions that are exposed on the Arabian continental margin (near Adıyaman) provide valuable insights into sedimentary, tectonic and climatic processes that affected the Southern Neotethys and its continental margins. Deposition in the region began with Aptian–Early Campanian shelf carbonates, followed by deepening during the Mid-Campanian. Lithoclastic–bioclastic turbidites accumulated along the downfaulted northern margin of the Arabian platform during the Campanian. A flexurally controlled foredeep developed in advance of the emplacement of Mesozoic allochthonous continental margin and oceanic rocks during the latest Campanian–Early Maastrichtian (e.g. supra-subduction zone Koçali ophiolite). Alluvial detritus was shed from the emplaced allochthon in non-marine to shallow-marine deltaic settings during latest Campanian–Early Maastrichtian. A marine transgression resulted in the establishment of a shallow-marine shelf during the mid-Maastrichtian. During the latest Maastrichtian, the platform submerged, initiating deeper-water hemipelagic sedimentation. Uplift took place during the Palaeocene resulting in sediment instability, slumping and formation of high-density, subaqueous gravity flows. In response to regional faulting and tilting, some areas in the north and the southwest emerged during the Early–Middle Eocene generating alluvial fans in a warm, humid climate that favoured oxidation and reddening. The likely control of the tectonic instability was far-field compression related to the latest stages of subduction of the Southern Neotethys or the initial stages of collision of the Arabian and Tauride continents. An Oligocene hiatus is likely to reflect the formation of a collision-related forebulge, followed by flexural subsidence to form an Early Miocene foreland basin. This was finally over-ridden by the northerly, active continental margin of the Southern Neotethys during Early–Mid Miocene. Regional suture tightening (Mid–Late Miocene) and related non-marine coarse clastic sedimentation was followed by westward ‘tectonic escape’ of the Anatolian microplate towards the Aegean region during Plio-Quaternary time.

Convective instability in sedimentation: 3-D numerical study

To provide a probable explanation on the field observed rapid sedimentation process near river mouths, we investigate the convective sedimentation in stably stratified saltwater using 3-D numerical simulations. Guided by the linear stability analysis, this study focuses on the nonlinear interactions of several mechanisms, which lead to various sediment finger patterns, and the effective settling velocity for sediment ranging from clay (single-particle settling velocity V0 = 0.0036 and 0.0144 mm/s, or particle diameter d = 2 and 4 μm) to silt (V0 = 0.36 mm/s, or d = 20 μm). For very fine sediment with V0 = 0.0036 mm/s, the convective instability is dominated by double diffusion, characterized by millimeter-scale fingers. Gravitational settling slightly increases the growth rate; however, it has notable effect on the downward development of vertical mixing shortly after the sediment interface migrates below the salt interface. For sediment with V0 = 0.0144 mm/s, Rayleigh-Taylor instabilities become dominant before double-diffusive modes grow sufficiently large. Centimeter-scale and highly asymmetric sediment fingers are obtained due to nonlinear interactions between different modes. For sediment with V0 = 0.36 mm/s, Rayleigh-Taylor mechanism dominates and the resulting centimeter-scale sediment fingers show a plume-like structure. The flow pattern is similar to that without ambient salt stratification. Rapid sedimentation with effective settling velocity on the order of 1 cm/s is likely driven by convective sedimentation for sediment with V0 greater than 0.1 mm/s at concentration greater than 10–20 g/L.

Middle Eocene Nummulites and their offshore re-deposition: A case study from the Middle Eocene of the Venetian area, northeastern Italy

The Middle Eocene Calcari nummulitici formation from northeastern Italy, Venetian area, represents a shallow-marine carbonate ramp developed on the northern Tethyan margin. In the Monti Berici area, its main components are larger foraminifera and coralline red algal communities that constitute thick carbonate sedimentary successions. Middle ramp and proximal outer ramp environments are recognized using component relationships, biofacies and sedimentary features. The middle-ramp is characterized by larger flattened-lenticular Nummulites on palaeohighs between which rhodoliths formed. Larger Nummulites palaeohighs containing Nummulites millecaput, Nummulites crassus, Nummulites discorbinus and Nummulites cf. gizehensis developed more basin-wards. The following relatively quiet environments of basin-wards of the palaeohighs represent areas of maximum carbonate production. The transition between the distal middle- and the proximal outer-ramp settings is marked in the study area by a large erosional surface which is interpreted to have been formed as a result of an erosive channel body filled in by deposits re-sedimented from shallower depths. These off-shore re-sedimented channelized deposits, ascribed to the Shallow Benthic Zone SBZ 15, lying on hemipelagic marls (planktonic foraminiferal zone E9 (P11)) allow for a biostratigraphic correlation to the Late Lutetian.The studied deposits, represented by packstone to rudstones, were displaced whilst still unlithified. The Lutetian–Bartonian regression along with the local tectonic activity promoted the production of a high amount of biogenic shallow-water carbonates mainly produced in the Mossano middle-ramp settings. These prograded towards the basinal areas with high-sedimentation rate of carbonate deposits characterized by the larger Nummulites rudstones. Such high amounts of sediment led to sediment instability which potentially could be mobilized either by return currents due to occasional major storms or by earthquakes induced by tectonic activity. These will have led to the offshore re-deposition of the Nummulites sediments into deeper water setting via the observed channels. Since potential migration pathways are short, such distal re-sedimented channel-filled material surrounded by hemipelagic marls is optimally placed for the formation of potential subsurface oil reservoirs.

Sediment accumulation rates and turbidite frequency in the eastern Algerian margin. An attempt to examine the triggering mechanisms

From the analysis of seven new sediment piston-cores sampled in 2005 (MARADJA-2 French–Algerian cruise), this study aims to identify for the first time possible late Pleistocene to recent sedimentary instabilities controlled by seismicity off or close to the eastern coast of Algeria. The detailed lithologic study allows us to identify the frequency of the gravity events (turbidites, debrites) and to discuss their geographical sources and triggering mechanisms. Based on a chronostratigraphy of 24 14C AMS datings, sediment accumulation rates in zones extending off Bejaia and Annaba and, in particular, semi-quantitative analysis of the microfossils and lithogenic tracers of the origin of gravity flows was discussed. Two sediment cores, here considered as reference cores, enabled the estimation of palaeoenvironmental parameters that controlled sedimentation: (1) in the prodelta of Soummam Oued, after 2215calyrBP, floods were less frequent and sediment accumulation rates decreased because of a drier climate; (2) in the middle slope to the NE of Annaba, a location shielded from gravity flows, an increased sedimentation rate coincided with the passage of warmer waters leading to maxima of carbonate biogenic fluxes (particularly pteropods). Off Bejaia, two deep sediment cores show a spectacular increase in sediment accumulation rate between 2200 and 1000calyrBP while turbidites become more frequent. According to the eustatic and climatic stability of this interval, an episode of strong slope instability of the slope is suggested. Both sediment cores on the slope of Annaba indicate an increase in gravity flows during the same last thousand years, which is tentatively related to a regional increase of seismicity during this interval. This spatial distribution of gravity events is clearly different to that of the western margin where the sedimentation is less perturbed.