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Recent high-definition re-logging of 27 diamond drill holes (9237 m) in the Keats Zone of New Found Gold Corp's Queensway project provides new insight into the area's local stratigraphy. Correlation of defined lithofacies of the Ordovician turbidite sequence in the Davidsville Group was supported by ME-ICP61 data (ALS Global) to validate observably different lithological units. Due to the lateral continuity of a chemically distinct (Ni-Cr enriched), coarsegrained unit in the footwall of the Appleton Fault Zone, this "Cr-Wacke" was deemed a marker horizon in the Keats Zone stratigraphy warranting further investigation. Lithological stacking patterns and sequence stratigraphic interpretations suggest that the Cr-Wacke represents part of a large submarine fan complex that experienced pro-gradation/retrogradation during relative sea-level change. The Cr-Wacke is defined by two distinct lithological units, referred to as the outer levee and interior package. The outer levee comprises a thickly bedded, well-sorted greywacke commonly interbedded with siltstones to the east. The interior package, bound on either side by the outer levee, is characterized by a thickly bedded immature greywacke with common conglomeratic lags and the presence of diagnostic fuchsite grains. The narrow, and discontinuous distribution of conglomeratic lags suggests they represent the braided channels of a mid-submarine fan, with the outer levee representing the transition from mid to lower fan deposition. General eastward stacking patterns of the steeply NW-dipping stratigraphy reflects the transition from regressive to transgressive facies deposition during the late falling stage through to the early transgressive systems tracts of a relative sea-level curve. [ABSTRACT FROM AUTHOR]

Carbonate sediments of nonglacial Cryogenian (659 to 649 Ma) and early Ediacaran (635 to 590 Ma) age exhibit large positive and negative δ13Ccarb excursions in a shallow-water marine platform in northern Namibia. The same excursions are recorded in fringing deep-sea fans and in carbonate platforms on other paleocontinents. However, coeval carbonates in the upper foreslope of the Namibian platform, and to a lesser extent in the outermost platform, have relatively uniform δ13Ccarb compositions compatible with dissolved inorganic carbon (DIC) in the modern ocean. We attribute the uniform values to fluid-buffered diagenesis that occurred where seawater invaded the sediment in response to geothermal porewater convection. This attribution, which is testable with paired Ca and Mg isotopes, implies that large δ13Ccarb excursions observed in Neoproterozoic platforms, while sedimentary in origin, do not reflect the composition of ancient open-ocean DIC. [ABSTRACT FROM AUTHOR]

Earth to air heat exchanger is a very old technique used 3000 years B.C in arid regions where that was called Qanat. In the present experimental study, the potentials of earth to air heat exchanger to provide thermal comfort for winter weather conditions in South west of Algeria described as arid region are investigated. An EAHE made of 66 meter of PVC tube and buried at 1.5 meter underground in agriculture zone equipped with 33 W fan was studied. Thermal and hygrometric analysis of air passing inside the tube form inlet to outlet was conducted. The results show the system was able to create two thermal regimes: heating regime with a gain of 13 °C (from 00h to 11h and from 17h to 23h) and cooling regime (from 12h to 16h) with 6 °C in the same day. Relative humidity was reduced by 32 % of 90 % of studied cases which stops the development of micro-organism and reducing Internal Air Quality. [ABSTRACT FROM AUTHOR]

Highlights • An experimental procedure to compare baseline working conditions and a set of failures is presented. • One advanced technique to analyze the signature or vibrating spectra for a Sirocco fan is used. • A Symmetric Dot Point Technique is applied to a centrifugal fan operating conditions. • Different vibrating levels are obtained and depict the overall working framework of the fan. • The technique to the particular application opens new possibilities for maintenance protocol. Abstract Sirocco fan units, also known as squirrel cage fans, are usually installed at the air conditioning systems of vehicles used in public transport. They must provide an accurate ventilation flow rate, with high efficiency and performance, but also without operative problems like underperforming, outages or breakdowns, which usually lead to compromise the comfort and quietness of the passengers. Due to their heavy duty, they are susceptible of such problems which finally cause poor ventilation, magnified in highly crowded situations, and important noise generation with uncomfortable vibrations. Periodic maintenance and regular monitoring are thus essential to control that the fan operative range ensures a correct operation. This paper deals with a series of working failures, typically encountered in industrial applications with Sirocco fans, like impeller unbalances, obstructed channels or blocked inlets. A database with vibration signals has been measured experimentally to obtain the forced response of the fan as a function of the flow rate for different troubled scenarios. Following, a Symmetrized Dot Pattern (SDP) technique, that transforms the temporal waveforms into polar maps, is employed to generate dot patterns which can discriminate between different working conditions and failures, allowing an easy visual identification. The final objective is to show the potentiality of this technique as a fault diagnosis methodology for typical squirrel cage fans, providing optimal parameters for its use. The results obtained are also compared with other diagnosis techniques, previously employed by the authors, for a complementary analysis of the vibrating condition of these centrifugal fans. [ABSTRACT FROM AUTHOR]

Sedimentological and petrographic studies of the Haymana Formation sandstones identify a submarine fan in the Haymana Basin. This study is confined to outcrop samples from the submarine-fan sandstones (the L1, L2, and L3 sections) and focuses on documentation of the petrographic characteristics of and depositional controls on reservoir properties of the Haymana Formation sandstones. Analysis of the lithology, texture, sedimentary structure, and petrography of the outcrop samples allows separation of the Haymana Formation sandstones into three distinct lithofacies, A, B, and C. Lithofacies A sandstones exhibit medium-coarse grain sizes (0.4–0.6 mm), moderate-good sorting, and subrounded grains. Lithofacies B sandstones exhibit fine grain sizes (0.2 mm), moderate sorting, and subrounded-subangular grains. Lithofacies C sandstones exhibit very fine grain sizes (0.112 mm) and nonreservoir facies. The main aim of this study is to document the diagenetic history and reservoir quality of the Haymana Formation sandstones. Lithofacies A has the best permeability, ranging from 80 to 120 mD, which can be related to the large grain size, the presence of cross-bedding, small amount of authigenic clays or cements in the pore throats, and enlarged pore apertures. In contrast, Lithofacies B sandstones contain variable yet small pore and pore-throat sizes, which are affected by abundant pore-filling authigenic clays, small grain sizes, and no dissolution. The permeability of the Lithofacies B sandstone ranges from 16 to 35 mD, which is lower than that of the Lithofacies A sandstone. Additionally, the Lithofacies B sandstones have small median pore-throat sizes (mean = 1.52 μm) and low porosities (average 4–6%), and the Lithofacies A sandstones have large pore-throat sizes (mean = 2.06–3 μm) and high porosities (average 20–25%), with most pore throats (50% or more) ranging between 1 and 4 μm. According to these data, the Lithofacies A sandstones show good reservoir characterisation. To date, significant hydrocarbon deposits have not been discovered in the Haymana Formation sandstones, although intensive exploratory work towards this end has been carried out in the Haymana Basin. According to this study, the proximal sandstones of the submarine-fan complex of the Haymana Formation may contain high-potential reservoirs in the Haymana Basin. In the basin, hydrocarbon is sourced from deep zones and may be capped by the proximal part of the Haymana Formation sandstones. According to this study, the Lithofacies B sandstones of the Haymana Formation are not suitable as diagenetic traps for hydrocarbon exploration in the Haymana Basin. However, the Lithofacies A sandstones may be expected to have the highest exploration success. [ABSTRACT FROM AUTHOR]

Sedimentary features such as channel sands and submarine fan sequences are important hydrocarbon reservoirs throughout the world and may be interpreted from bed thickness trends and log motifs. The log motifs of four well logs were employed during this study to delineate reservoir architectural depositional features and environment, determine their lithological attributes, and evaluate reservoir properties. Gamma ray log signatures were utilized to infer depositional features, discriminate litho-units, and define depositional environment; resistivity log was employed to identify reservoir zones and formation fluids, while the combined density and neutron logs aided in the estimation of reservoir porosity and lithological typing. Results of analysis show seven laterally discontinuous reservoirs: one in Well X (X2), three in Well Y (Y1, Y2, Y3), and three in Well W (W1, W2, and W3) with thicknesses of 6.2 m, 19.2 m, 7.6 m, 78.7 m, 100.9 m, 38.1 m, and 41.6 m, respectively. Reservoirs architecture reveal distributary channel sands, submarine fan lobes, and deep tidal channel-fills deposited within the deep marine mud-rich N'kapa Formation. Average porosity, water saturation, and hydrocarbon saturation values of Well X and Well Y reservoirs are 20.8%, 30.8%, 69.2%, and 40.2%, 18.3%, 81.7%, respectively, indicating moderate-to-good reservoir quality. Also, the permeability values are moderate to good (74.89–12,584 md), except for Y3 and Well W reservoirs whose well log-derived permeabilities were unreliable due to their non-irreducible nature. Density-neutron crossplots indicate heterogeneous reservoir lithologies comprising of limestone, dolomite, and sandstones, with predominant calcite and subordinate dolomite as mineral matrix. Crossplot of water saturation and porosity revealed grain-size variation ranging from fine-grained to silty sediments with bulk volume water values suggesting Well X and Y reservoirs to be homogeneous and will produce water-free hydrocarbons, while Well W reservoirs are heterogeneous water-prone reservoirs. [ABSTRACT FROM AUTHOR]

Year-round and efficient production for crop products of high yield, quality and cleanliness is the development trend of the Chinese solar greenhouse (CSG). However, this is limited by unfavorable climate conditions inside the CSG, such as high air temperature in warm seasons. The fan-pad cooling system, normally adopting negative pressure ventilation, has been widely used for greenhouse cultivation. But it generates a large air temperature gradient in greenhouse, limits the greenhouse dimensions. Above deficiencies are more serious in the CSG. Because CSG always has a long distance between the sidewalls, fans and gaskets are installed separately on the sidewalls. In order to overcome the limitations of negative fan-pad cooling system and improve ability of the CSG in coping with high temperature, a positive pressure fan-pad cooling system (PPFPCS) was designed in this study. By using this system, the cold and humid air enters the CSG from bottom of south roof, and then hot air leaves the CSG through roof vents. Performance of the PPFPCS was tested in a CSG without crops in Beijing area during summer. Results showed that in typical summer hot days, the PPFPCS cooperating with external shading net could decrease mean air temperature of the CSG experimental area to 30.7-33.4 °C, which was lower than that in the CSG contrast area using natural ventilation combination with external shading net by 5.4-11.1 °C. Air temperature of the CSG experimental area was also lower than that outside the CSG with a temperature difference of 2.4-5.4 °C. Nevertheless, both natural and mechanical ventilations were tested to have limited cooling capacity to meet climate requirement for CSG cultivation. The PPFPCS could also decrease the CSG air temperature at night, but had a poorer performance in comparison with daytime cooling due to the smaller vapor pressure deficit (VPD). The contrast area of CSG encountered an extreme low air humidity state with mean VPD of 3.4-6.1 kPa. PPFPCS could effectively alleviate low humidity stress: the average relative humidity in CSG experimental area was between 49.8% and 62.3%, which was 13.6% - 21.2% higher than that in CSG control area and 13.6% - 24.6% higher than that in outdoor area. Wind velocity inside the CSG experimental area ranged from 0.35 to 1 m/s, which indicated a relative uniform air flow distribution. Cooling efficiency of the PPFPCS was about 91%, which was over 10% higher than that of the traditional negative pressure fan-pad cooling system. Low temperature of the PPFPCS circling water contributed to the high cooling efficiency. Average water consumption rate of the PPFPCS used for CSG cooling was 0.035-0.079 g/(m2·s) during the test. It had a positive linear correlation with VPD of outdoor air, that is drier outdoor air anticipates larger water consumption and better cooling performance. Both cooling load model of the CSG and selection method for fan-pad cooling system were derived. Cooling load model is the basis for capacity calculation of cooling equipment to be installed. Cooling load of the CSG in summer was 299.1 W/m2. Contribution ratios of convective heat transfer between north wall and indoor air, convective heat transfer between greenhouse floor with indoor air, hot air infiltration, as well as heat transfer between indoor and outdoor air though south roof, north roof and side walls were 11.0%, 73.3%, 1.3% and 14.4%, respectively. The maximum specific ventilation rate of the PPFPCS used for CSG cooling was recommended to be 0.067 m/s. This study can provide technical support for the application of PPFPCS in CSG cultivation and provide theoretical basis for the climate control of CSG production in summer. [ABSTRACT FROM AUTHOR]

Taking some steam flooding experimental area in the western depression of the Liaohe Basin in China as an example, it quantitatively evaluates the flow units of the sedimentary facies in fan delta front and analyzes the influences of the flow units on the development of the oilfields. Comprehensive analysis of multifarious data such as geology, core analysis and well logs indicates that porosity, permeability and FZI are key parameters for classification and evaluation of the reservoir flow units. Then using SPSS cluster analysis software platform, cluster analysis are conducted on reservoir physical properties of cored wells, and based on which discriminant analysis are performed to obtain the discriminant formula. The discriminant analysis of reservoir physical properties of the wells without core data is based on fine interpretation of well logging data. Combined with the results of cored wells, the classification and evaluation of the flow units has been completed in the target layer of ​​the whole study area. Finally the flow units are divided into four classes, namely, Class A, Class B, Class C and Class D. Classes A and B flow units represent high-quality reservoirs. The flow units are mainly controlled by sedimentation. Classes A and B are mainly sedimentary microfacies of underwater distributary channel and distributary mouth sand bar. The paper proposes five principles of judging the rationality of flow units, describes the development characteristics of different classes of flow units on section and plane, analyzes the influence of flow units on oilfield development and suggests countermeasures. Specially, in the process of steam flooding, target injection layers should be optimized and steam injection pressure should be effectively controlled to prevent steam channeling; when planning infill wells, injection and production wells should be deployed in the same class of flow unit to ensure good connectivity; the development of remaining oil should focus on Classes A and B flow units, and meanwhile pay more attention to the fine interpretation results of well logging data. • The classification and evaluation method of flow units combined with genetic analysis and clustering analysis. • Key parameters optimized for classification and evaluation of the reservoir flow units. • Five principles of judging the rationality of flow units. • Analyzing of the influences of flow units on oilfield development and suggests countermeasures. [ABSTRACT FROM AUTHOR]

Calcareous nannofossils found in the Cergowa beds of the Dukla and Fore-Dukla tectonic units in the Outer Carpathians indicate a time of deposition in the range of the NP23–NP24 nannoplankton zones of the Lower Oligocene. Nannoplankton assemblages reflect the paleoecological changes at the Eocene–Oligocene transition from: (i) a greenhouse to an icehouse climate; (ii) brackish to normal salinity suggesting open sea conditions, which were controlled by the Paratethys Basin closure followed by opening and connection with the Tethyan Ocean. The absence of nannofossils of NP25 zone, but their presence in the tectonic windows between 40 and 80 km to the west, shows that deposition of the Cergowa beds in the western part of the basin lasted longer than in the east. Occurrences of nannofossils indicating zones NP16 and NP21, found in the uppermost mudstone-rich parts of studied sections, may prove the remobilization and redeposition of sediments of this stratigraphic age. Potentially, eroded material could be derived from some of the following lithostratigraphic units: NP16 — the Hieroglyphic beds, Przybyszów sandstones and Upper variegated shales; NP21 — the Globigerina marls, Mszanka sandstones and sub-Chert marls and shales and/or fine-grained equivalent of these units. Reworked specimens derived from the older Mesozoic strata occur occasionally in various samples. [ABSTRACT FROM AUTHOR]

Rambatan Formation in the western part of North Serayu Basin, Brebes, Central Java, comprises generally flysch facies of turbidite sediments deposited in a deep marine environment. This formation is equivalent to Merawu Formation found in the eastern part of the basin and deposited in the environment of tidal flat to subtidal. The turbidite sediments were highly controlled by a rapid downward movement taking place continuously during Early to Late Miocene. The variation of the depositional environment has been the object of this research which aims to understand the sedimentation process of Rambatan Formation in this type locality with a modern turbidite approach. Rambatan Formation was deposited in N13-N19, as a deep marine sediment channel, turbidite, and deep marine tidal zone. The sedimentation was affected by gravity flow and bottom current. The sediments on N13-N14 were marked by turbidite sediments until Middle N17. The sediment supply increased on Middle N17, as a sediment filler on a channel marked by contourite mud layer (muddy slump) and debris flow, with sources from the north. The increase of sediment supply was followed by an environmental transformation from a deep marine channel into deep marine tidal area. In N19, the sediments were redeposited as turbidite sediment, starting with debris flow in Middle N18. [ABSTRACT FROM AUTHOR]

The Upper Cretaceous Prairie Canyon Member of the Mancos Shale, Book Cliffs, Utah, contain outstanding examples of prodeltaic turbidity and hyperpycnal flow deposits. Sandstone‐rich, heterolithic and mudstone‐rich channel fills occur near the north‐west entrance to Tusher Canyon, Gunnison Butte and Bootlegger Wash. Mudstone‐rich and heterolithic‐rich hyperpycnal channel deposits are mostly unbioturbated, locally displaying a few specimens of Phycosiphon incertum, Protovirgularia dichotoma, Rosselia socialis, Schaubcylindrichnus coronus and Palaeophycus tubularis. Sandstone‐rich channel deposits consist of wave‐reworked turbidites and hyperpycnites, containing Helminthoidichnites tenuis, Lockeia siliquaria, Phycodes isp., Phycosiphon incertum, Protovirgularia dichotoma, Rosselia socialis, Skolithos linearis and Fugichnia. Scolicia isp. and Chondrites isp. occur locally. Strata along the south‐west entrance of Tusher Canyon record deposition in a prodelta turbidite lobe, but far from its axis. With the exception of a few specimens of Ophiomorpha isp., bioturbation is restricted to the top of the succession, where Curvolithus simplex, Gyrochorte comosa, Lockeia siliquaria, Palaeophycus tubularis and Ptychoplasma excelsum occur. Strata at Hatch Mesa record deposition in a hyperpycnal lobe, near to its axis. Sandstone beds include Curvolithus simplex, Gyrochorte comosa, Ophiomorpha nodosa, Palaeophycus tubularis, Phycosiphon incertum, Protovirgularia dichotoma, Ptychoplasma excelsum, Schaubcylindrichnus freyi, Skolithos linearis, large specimens of Rosselia socialis and indeterminate crustacean burrows. Chondrites isp. is present in the mudstone. High rates of both episodic and sustained sedimentation, degree of substrate consolidation, freshwater discharge and water turbidity are the most important stress factors in both channels and lobes. Taxonomic composition, uneven distribution of bioturbation through the successions, and overall low ichnodiversity help to distinguish these prodeltaic deposits from bathymetrically equivalent offshore strata in the same basin. Hyperpycnal flow deposits are formed in a wide variety of environmental settings, therefore displaying high ichnological variability. Such variability is summarized by characterising ichnofaunas from four different depositional settings: (i) lakes; (ii) shelf deltas; (iii) shelf‐edge deltas; and (iv) deep‐marine systems. [ABSTRACT FROM AUTHOR]

Sediment waves are commonly observed on the sea floor and often vary in morphology and geometry according to factors such as seabed slope, density and discharge of turbidity currents, and the presence of persistent contour currents. This paper documents the morphology, internal geometry and distribution of deep‐water (4000 to 5000 m) bedforms observed on the sea floor offshore eastern Canada using high‐resolution multibeam bathymetry data and seismic stratigraphy. The bedforms have wavelengths of >1 km but fundamentally vary in terms of morphology and internal stratigraphy, and are distinguished into three main types. The first type, characterized by their long‐wavelength crescentic shape, is interpreted as net‐erosional cyclic steps. These cyclic steps were formed by turbidity currents flowing through canyons and overtopping and breaching levées. The second type, characterized by their linear shape and presence on levées, is interpreted as net‐depositional cyclic steps. These upslope migrating bedforms are strongly aggradational, indicating high sediment deposition from turbidity currents. The third type, characterized by their obliqueness to canyons, is observed on an open slope and is interpreted as antidunes. These antidunes were formed by the deflection of the upper dilute, low‐density parts of turbidity currents by contour currents. The modelling of the behaviour of these different types of turbidity currents reveals that fast‐flowing flows form cyclic steps while their upper parts overspill and are entrained westward by contour currents. The interaction between turbidity currents and contour currents results in flow thickening and reduced sediment concentration, which leads to lower flow velocities. Lower velocities, in turn, allow the formation of antidunes instead of cyclic steps because the densiometric Froude number (Fr′) decreases. Therefore, this study shows that both net‐erosional and net‐depositional cyclic steps are distributed along channels where turbidity currents prevail whereas antidunes form on open slopes, in a mixed turbidite/contourite system. This study provides insights into the influence of turbidity currents versus contour currents on the morphology, geometry and distribution of bedforms in a mixed turbidite–contourite system. [ABSTRACT FROM AUTHOR]

On the basis of the actively controlled multiple-fan wind tunnel we designed, this paper proposes a latticed mode–based control strategy for the fan array. The so-called latticed mode is the overall topology of the working fans. In order to investigate the simulation ability of the latticed mode, several latticed modes are designed to analyze the temporal and spatial properties of generated wind fields. Airflow data under different latticed modes are measured using nine two-dimensional anemometers, and then, statistical indicators of wind speed and wind direction, as well as the spatial uniformity and complexity of generated wind fields, are calculated to analyze the characteristics of wind records. The results indicate that the distribution of active fans in the latticed mode has significant influence on the statistical properties and spatial evolutions of wind speed and direction. Besides, the latticed modes can regulate the spatial uniformity and complexity of the wind fields. The latticed modes with a high clustering degree of active fans can generate wind fields with low spatial uniformity and high complexity. In addition to the fan voltage and the rotation angle of swivel plates, the proposed latticed mode provides more possibilities for wind field simulation. [ABSTRACT FROM AUTHOR]

Submarine fans are the largest sediment accumulations on Earth and are key to study the sediment-transfer zone between terrestrial source area and deep-sea depositional sink. They provide information of past climate, tectonics, carbon global inventory, and can be prolific hosts for oil/gas resources. In this paper, we present, for the first time, an analysis of the entire Magdalena Submarine Fan (MSF), from the shelf break to the distal domain, based on ~224,000 km2 of multibeam bathymetry, as well as backscatter, subbottom profiler and regional/local seismic reflection data recently acquired in southwestern Caribbean Sea. The aim is to describe in detail the MSF morphology and depositional architecture, propose a fan segmentation landform assemblage, and determine its extent within the deep basin. Three fan segments are identified: upper, middle and lower fans. The upper fan extends from the coastline to a depth of ~3000 m. Its eastern sector is characterized by a canyon system off the present-day mouth of the Magdalena River, through which most of the sediments are transported downslope to be deposited in intra-slope basins bounded by structural highs of the South Caribbean Deformed Belt. The western upper fan is characterized by distinct channel-levee complexes that are partially removed by mass transport complexes that originated near the continental shelf edge. The upper to middle fan transition is marked by a decrease in regional gradient from 1° to about 0.3° and local relief, a change from large, irregular sediment waves to more regular waves that slowly decrease in amplitude downslope, and the appearance of erosional megascours. The middle fan bedform assemblage evidences the presence of a channel-lobe transition zone in this sector of the MSF, separating well-defined, upper fan channels from lower fan depositional lobes. The middle to lower fan transition occurs between ~3800 and ~3950 m and is defined by a further decrease in gradient and by a change from sediment waves to planar parallel-bedded reflectors on subbottom profiles. The lower fan extends to a maximum depth of ~4250 m and is characterized by an almost flat seabed (slope of 0.05°), interrupted by a few isolated bathymetric highs and low-relief channels (<5 m deep). The entire area of the lower fan is interpreted as an area of turbidity current deposition, with relatively sandy sediments in the south and west giving way to muddier sediments in the northeast, which could correspond to distal fan lobes. The identification of four regional seismic facies related to MSF sedimentation allowed us to constrain the fan extent in the southwestern sector of the Caribbean. Distally, within the Colombia Basin the fan terminates against areas of elevated seafloor (Kogi-Coyaima and Quimbaya seamounts, Aruzi and Ticuna hills, and Beata Ridge), which have acted as barriers to sedimentation. Nevertheless, it was determined that the MSF extends beyond the Colombia Basin and locally reaches the Lower Nicaraguan Rise. In this new scenario, we established that the MSF is much more extensive than previously recognized, with an area of ~237,000 km2, which puts it among the World's largest submarine fans. • The morpho-structure of the entire Magdalena Submarine Fan (MSF) is presented • Upper, middle and lower fan segments are proposed from diverse landform assemblages • Channel-levee complexes partially removed by extensive MTCs defines the upper fan • Middle fan, with sediment waves and megascours, is defined as sediment bypass area • Evidence of turbidity current sedimentation, with probable lobes, in the lower fan [ABSTRACT FROM AUTHOR]

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Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current understanding of tsunamis generated by volcanic-island landslides is reliant on numerical models benchmarked against reconstructions of past events. As the largest historical event with timed tsunami observations, the 1888 sector collapse of Ritter Island, Papua New Guinea provides an outstanding opportunity to better understand the linked process of landslide emplacement and tsunami generation. Here, we use a combination of geophysical imaging, bathymetric mapping, seafloor observations and sampling to demonstrate that the Ritter landslide deposits are spatially and stratigraphically heterogeneous, reflecting a complex evolution of mass-flow processes. The primary landslide mass was dominated by well-bedded scoriaceous deposits, which rapidly disintegrated to form an erosive volcaniclastic flow that incised the substrate over much of its pathway. The major proportion of this initial flow is inferred to have been deposited up to 80 km from Ritter. The initial flow was followed by secondary failure of seafloor sediment, over 40 km from Ritter. The most distal part of the 1888 deposit has parallel internal boundaries, suggesting that multiple discrete units were deposited by a series of mass-flow processes initiated by the primary collapse. The last of these flows was derived from a submarine eruption triggered by the collapse. This syn-collapse eruption deposit is compositionally distinct from pre- and post-collapse eruptive products, suggesting that the collapse immediately destabilised the underlying magma reservoir. Subsequent eruptions have been fed by a modified plumbing system, constructing a submarine volcanic cone within the collapse scar through at least six post-collapse eruptions. Our results show that the initial tsunami-generating landslide at Ritter generated a stratigraphically complex set of deposits with a total volume that is several times larger than the initial failure. Given the potential for such complexity, there is no simple relationship between the volume of the tsunamigenic phase of a volcanic-island landslide and the final deposit volume, and deposit area or run-out cannot be used to infer primary landslide magnitude. The tsunamigenic potential of prehistoric sector-collapse deposits cannot, therefore, be assessed simply from surface mapping, but requires internal geophysical imaging and direct sampling to reconstruct the event. • Ritter Island's sector collapse provides an exemplar of volcanic tsunami hazards. • Deposit heterogeneity reflects erosion, secondary failure and a triggered eruption. • The volume of the distal deposit alone far exceeds the tsunamigenic failure. • A single catastrophic collapse led to stratigraphically complex distal deposits. • Accurate assessment of tsunami potential requires internal imaging and sampling. [ABSTRACT FROM AUTHOR]

Carboniferous glaciogenic strata (Itararé Gp.) in the southernmost Paraná Basin, Brazil exhibit soft-sediment deformation features previously interpreted as glaciotectonism. These sediments were studied in detail to confirm that they were deformed by ice and to assess the nature of the glaciation, depositional environments, and paleoclimate in this region during the Carboniferous. Five outcrops were described along a railroad transect that contains a conglomerate and diamictite facies with striated and faceted clasts, a medium sandstone facies, a fine grained silt/clay rhythmite and mudstone facies with dropstones and diamictite pellets, a sandy clinoform facies, and a folded sandstone with interbedded mudstone facies. The depositional environment for these sediments is interpreted as an outwash fan and fan delta from an ice-proximal, transitional terrestrial-to-estuarine setting. Rb/K values from the rhythmites reflect a transition from a freshwater to brackish environment and the Chemical Index of Alteration (CIA) of the rhythmites ranges from 65 to 73, reflecting a relative increase in the degree of chemical weathering through time. Deformation features include widespread folding, thrust faults, hydrofractures, décollement surfaces, and piggyback fold-thrust complexes. The deformation is interpreted as evidence of a push-moraine complex formed by at least two complete ice advance/retreat cycles. The occurrence of décollement surfaces, plastically deformed proglacial sediments, and hydrofractures indicate a dynamic, warm-based or polythermal glacier. Abundant outwash sediments, rhythmites with dropstones, and the shift to average CIA values all support a temperate paleoclimate. Deformation structures indicate a NW direction of ice shove that is in agreement with the regional-scale hypothesis that a NNW flowing lobe extended out of Uruguay during the Carboniferous and terminated in the southernmost Paraná Basin. This study demonstrates that late Paleozoic glaciation in this region was more dynamic than previously understood, with high frequency fluctuations in ice marginal positions. [ABSTRACT FROM AUTHOR]

Between 22 and 17 cal ka BP, five large meltwater events from within the Laurentian Channel Ice Stream deposited mud beds meters thick across a large area of the Laurentian Fan and adjacent continental slopes. This study determines the sources of these event beds and relates them to the glaciological evolution of the retreating Laurentian Ice Stream. We analyzed major element and magnetic mineral contents of these event beds and compare them with a new collection of 80 source reference samples from the Gulf of St. Lawrence area. Element ratios suggest a steady compositional change from older to younger outburst event beds, while element-specific offsets from reference sample compositions indicate grain-size and mineral/element partitioning during suspension transport. Their magnetic properties place event beds on the source mixing trend of four reference samples groups, which represent two magnetite-rich sources (Canadian Shield and/or Southern Newfoundland) and two hematite-rich sources (Appalachian red beds). Using a deterministic linear source mixing model based on IRM 100mT , HIRM and Ca%, we find that the earlier two outburst events had higher contributions from granitic and calcareous sources than the later three events. Combining materials, timing and scenarios of the outburst events with ice-sheet retreat and ice-stream dynamics, we argue that the subglacial sediment depocenter of the earlier two event beds was located in the lower Laurentian Channel while that of the later three events was upstream from Cabot Strait. • Event bed sediments unmixed from new Gulf of St. Lawrence reference sample data. • Hematite, magnetite and calcite are most indicative tracer minerals for provenance. • Quantify contributions from surrounding red-bed, granite and carbonate rock provinces. • Demonstrate element partitioning by subglacial outwash and hyperpycnal plume transport. • Sediments premixed in subglacial depocenters above outer and inner Laurentian Moraines. [ABSTRACT FROM AUTHOR]

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The alluvial fan of Lima is a complex landform, resulting from the sediment contributions of the Rimac River and the coalescence of the alluvial fans of the tributaries of the Rimac River. Depositional zones in the fan and changing main channel and distributary channels are influenced by the palaeo-relief inherited from a semi-arid climate and by the climatic changes. The upper sedimentary sequence of the fan, dominant on the Costa Verde, is of Upper Pleistocene—Holocene age. The sediments forming it are non-cohesive and are highly mobile during floods and earthquakes. The dominant features in this sequence, intertwined channel facies and laminar flows, were influenced by the Pleistocene—Holocene postglacial marine transgressions. A deeper understanding of the evolution of the Lima alluvial fan provides insight in to the fan's future evolution in the framework of active tectonics and climate change. The Lima fan is an area with high human population density and is subjected to floods and debris flows resulting in subsequent loss of human life and properties. Therefore, the improved understanding of the fan's evolution, resulting from this study, will contribute to a better definition of high risk areas of potential human disaster caused by these natural processes. Cyclic-fan-development, presently controlled by glacial sea level lows and palaeo-topography will continue regardless of human intervention in attempts to prevent natural disasters in Lima. [ABSTRACT FROM AUTHOR]

Turbidity currents are powerful flows of sediment that pose a hazard to critical seafloor infrastructure and transport globally important amounts of sediment to the deep sea. Due to challenges of direct monitoring, we typically rely on their deposits to reconstruct past turbidity currents. Understanding these flows is complicated because successive flows can rework or erase previous deposits. Hence, depositional environments dominated by turbidity currents, such as submarine channels, only partially record their deposits. But precisely how incomplete these deposits are, is unclear. Here we use the most extensive repeat bathymetric mapping yet of any turbidity current system, to reveal the stratigraphic evolution of three submarine channels. We re-analyze 93 daily repeat surveys performed over four months at the Squamish submarine delta, British Columbia in 2011, during which time >100 turbidity currents were monitored. Turbidity currents deposit and rework sediments into upstream-migrating bedforms, ensuring low rates of preservation (median 11%), even on the terminal lobes. Large delta-lip collapses (up to 150,000 m3) are relatively well preserved, however, due to their rapidly emplaced volumes, which shield underlying channel deposits from erosion over the surveyed timescale. The biggest gaps in the depositional record relate to infrequent powerful flows that cause significant erosion, particularly at the channel-lobe transition zone where no deposits during our monitoring period are preserved. Our analysis of repeat surveys demonstrates how incomplete the stratigraphy of submarine channels can be, even over just 4 months, and provides a new approach to better understand how the stratigraphic record is built and preserved in a wider range of marine settings. • Repeat seafloor surveys reveal how stratigraphy is built in submarine channels. • Flow monitoring, seafloor surveys & coring are integrated. • Active submarine channels preserve 11% of deposits (median). • Infrequent but powerful flows can erase depositional record. • New method can be applied in a wider range of submarine systems. [ABSTRACT FROM AUTHOR]

The identification of sediment drifts typically relies on interpretation of reflection seismic data sets. This study sedimentologically analyzed an example of a carbonate delta drift previously identified in seismics in order to provide a catalogue of characteristic features at core and seismic scale for allowing testing the occurrence of this poorly known type of deposit elsewhere. Cores and downhole logs recovered during International Ocean Discovery Program Expedition 359 to the Maldives, in combination with seismic data, were analyzed with this objective. The diagnostic criteria for the sedimentological recognition of a delta drift are: (i) the development of sigmoidal clinoforms that thin out towards proximal and distal settings; (ii) a proximal part characterized by coarse‐grained facies with abundant shallow‐water components and distal areas dominated by fine‐grained facies with rare to absent shallow‐water components; (iii) winnowing of the finer fraction in proximal facies; (iv) extensive fragmentation of most of the bioclasts with minor intervals of well‐preserved components; (v) bigradational intervals in the proximal part and large channels in proximal to distal settings; and (vi) the lobe to delta shaped outline of the sediment accumulation. The characteristic shallow‐water fossil assemblage of the Mid to Upper Miocene delta drift consists of large benthic foraminifera (Amphistegina, Cycloclypeus, Lepidocyclina, Operculina and Heterostegina), fragmented red algae and bryozoans, equinoid debris, and Halimeda plates. The deeper‐water part of the drift bodies consists of fine‐grained planktonic foraminifera‐rich wackestone. Condensed intervals may occur as result of enhanced bottom‐current activity. In contrast to siliciclastic drift bodies, the carbonate delta drift has an important contribution by in situ shallow‐water carbonate production reminiscent of a shoal. In situ carbonate production is proposed as a major controlling factor which is as important as the pelagic settling or the shaping by density and bottom currents in siliciclastic drifts. In the absence of three‐dimensional data and in two‐dimensional views the carbonate delta drift sediment bodies resemble carbonate ramps, which indicates that there may be the need to re‐evaluate various cases of such systems described from the geological record. [ABSTRACT FROM AUTHOR]

Carbonate environments inhabit the realm of the surface, intermediate and deep currents of the ocean circulation where they produce and continuously deliver material which is potentially deposited into contourite drifts. In the tropical realm, fine‐grained particles produced in shallow water and transported off‐bank by tidal, wind‐driven, and cascading density currents are a major source for transport and deposition by currents. Sediment production is especially high during interglacial times when sea level is high and is greatly reduced during glacial times of sea‐level lowstands. Reduced sedimentation on carbonate contourite drifts leads to early marine cementation and hardened surfaces, which are often reworked when current strength increases. As a result, reworked lithoclasts are a common component in carbonate drifts. In areas of temperate and cool water carbonates, currents are able to flow across carbonate producing areas and incorporate sediment directly to the current. The entrained skeletal carbonate particles have variable bulk density and shapes that lower the prediction of transport rates in energy‐based transport models, as well as prediction of current velocity based on grain size. All types of contourite drifts known in clastic environments are found in carbonate environments, but three additional drift types occur in carbonates because of local sources and current flow diversion in the complicated topography inherent to carbonate systems. The periplatform drift is a carbonate‐specific plastered drift that is nearly exclusively made of periplatform ooze. Its geometry is built by the interaction of along‐slope currents and downslope currents, which deliver sediment from the adjacent shallow‐water carbonate realm to the contour current via a line source. Because the periplatform drift is plastered on the slopes of the platforms it is also subject to mass gravity flow and large slope failures. At platform edges, a special type of patch drift develops. These hemiconal platform‐edge drifts also contain exclusively periplatform ooze but their geometry is controlled by the current around the corner of the platform. At the north‐western end of Little and Great Bahama Bank are platform‐edge drifts that are over 100 km long and up to 600 m thick. A special type of channel‐related drift forms when passages between carbonate buildups or channels within a platform open into deeper water. A current flowing in these channels will entrain material shed from the sediment producing areas. At the channel mouth, the sediment‐charged current deposits its sediment load into the deeper basin. With continuous flow, a submarine delta drift is built that progrades into the deep water. The strongly focused current forming the delta drift, is able to rework coarse skeletal grains and clasts, making this type of carbonate drift the coarsest drift type. [ABSTRACT FROM AUTHOR]

The Temburong Formation comprises fine grain flysch, deposited in a distal part of a submarine fan system. Twenty five taxa of ichnofossils were identified. The ichnofossils are grouped into the Nereites ichnofacies. The ichnofacies was further divided into two subichnofacies namely Paleodictyon and Ophiomorpha rudis subichnofacies. The Paleodictyon subichnofacies is characterized by a high diversity of ichnofossils, discovered in the medium to thinly bedded turbidite at a distal lobe of a submarine fan. The Ophiomorpha rudis subichnofacies contains low diversity and is commonly found in thick-bedded sandstone channels and proximal lobes of a submarine fan system. [ABSTRACT FROM AUTHOR]

We use new U-Pb detrital zircon (DZ) geochronology from the Pleistocene Amazon submarine fan (n = 1352 grains), integrated with onshore DZ age data, to propose a sedimentary model for sea level-modulated and hydroclimate-modulated sediment transfer in Earth's largest source-to-sink system. DZ ages from the modern Amazon River sediment display a progressive downstream dilution by older cratonic zircons, leading to the expectation of a submarine fan with high proportions of craton-derived sediment. Our new DZ age data from the submarine fan and mixture modeling suggest that higher proportions of sediment were supplied from the distant central Andes to the Amazon fan during the last two glacioeustatic lowstands, and thus the observed DZ age spectra of the modern lower Amazon River indicate a relative increase in craton-derived sediment during the Holocene. We interpret that during interglacials, when sea level was high and the submarine fan inactive, the lower Amazon River did not efficiently transfer sand-sized sediment to the margin and thus became enriched in craton-derived sediment. During sea-level lowstands, increased gradients and incision in the lower Amazon River due to base-level lowering resulted in enhanced connectivity and transfer of Andes-sourced zircons to the deep sea. These results are also consistent with interpreted patterns of Andean-Amazon hydroclimate anti-phasing (enhanced precipitation in the central Andes and increased aridity in the northern Amazon Basin) during the Last Glacial Maximum. Our results suggest that sand-sized sediment in the Amazon submarine fan records multi-millennial patterns of sea level and South American hydroclimate. [ABSTRACT FROM AUTHOR]

Submarine channel and fan deposits form the largest sediment accumulations on Earth and host significant reservoirs for hydrocarbons. While many studies of ancient fan deposits describe architectural variability along 2D transects (e.g. axis‐to‐fringe, proximal‐to‐distal), these relationships are often qualitative and are rarely quantified at the event‐bed scale. In order to enable quantitative comparison of the fine‐scale architecture of submarine depositional environments, 56 bed‐scale outcrop correlation panels from five broadly categorized environments (channel, levee, lobe, channel‐lobe transition zone, CLTZ and basin plain) were digitized. Measured architectural parameters (bed thickness, bed thinning rates, lateral correlation distance, net‐to‐gross) provide a large (n = 28,525) and statistically robust framework to compare event‐bed architectures within and between environments. "Thinning rate" data (i.e. the lateral rate of change of bed thickness) clearly differentiate deposits from different submarine depositional environments, helping to quantify generally accepted models for proximal‐to‐distal evolution of stratigraphic architecture. The thinning rates of sandstone beds and mudstone‐dominated intervals vary predictably between environments. For example, the highest sandstone thinning rates occur in channel deposits (0.2–6 cm/m; P10 and P90 values here and below) and decrease to lobe (0.1–1.6 cm/m), CLTZ (0.2–0.9 cm/m), levee (0.0024–0.078 cm/m) and basin‐plain deposits (0.000017–0.0054 cm/m). These quantitative relationships provide valuable insights for downslope flow evolution and the construction of stratigraphic architecture in submarine settings. Due to intra‐environment variability, net‐to‐gross is highly variable and thus (when considered alone) is not a diagnostic indicator of depositional environment. Submarine lobe deposits show the most variability in event bed thickness, thinning rate and net‐to‐gross, likely due to the inherent facies variability and differing boundary conditions. To explore this variability, lobe deposits were sub‐classified based on position (proximal, distal) and effective confinement (unconfined, semiconfined, confined) to provide a more detailed sub‐environment analysis. Unconfined lobe deposits show a proximal‐to‐distal increase in sandstone thickness and decrease in mudstone thickness, supporting conceptual models. Confined lobe deposits have thicker sandstone and mudstone beds and lower net‐to‐gross values as compared to unconfined and semiconfined lobes, supporting a sediment trapping mechanism by confinement. These quantified bed‐scale parameter comparisons enable the recognition of architectural similarities and differences within and between environments, demonstrating the need for more quantitative studies of bed‐scale heterogeneity. The results from this study are immediately applicable to parameterizing forward stratigraphic models, constraining property distribution in reservoir models, and probabilistic determination of depositional environment from outcrop and core descriptions of submarine depositional environments. [ABSTRACT FROM AUTHOR]

The Bengal Fan, as the largest submarine fan in the world, receives a large amount of sediments discharged from the Himalayas through the Ganges-Brahmaputra (G-B) river system. However, previous studies of this system seldom focused on the role of channels, which are widely developed in the Bengal Fan, in sediment transportation over the last glacial cycle. Here, we discuss the coupled sedimentary archive in two gravity cores along the Active Channel in the Bengal Fan. Our findings are based on grain size, clay minerals, and Sr and Nd isotope compositions of these two sediment cores. End-member modeling of grain-size data reveals that the intermediate end-member represents the flux of distal fluvial particles from the G-B river system, the fine end-member denotes regional sediment supply of weathered volcanic materials, especially from the eastern Indian Peninsula, and the coarse end-member probably reflects nearby terrigenous input, aeolian input and/or volcanic glass. Sediment provenance analysis based on clay minerals, and Sr and Nd isotopes confirmed sediment supply from the G-B river system which was characterized by high illite percentage, high 87Sr/86Sr ratios and low ε Nd values, especially during five stages (50–45 ka, 42–37 ka, 31–28.5 ka, 24–20 ka and 14–9 ka). During these stages, heavy fine-grained sediment supply from the G-B river system was discharged into the study area under the influence of climate change rather than sea-level fluctuation, additionally emphasizing the importance of channels in the sediment transport process. Moreover, we find a significant alteration of sediment sources at ∼26 ka, which may be related to conversion of the deep-water currents in the Bay of Bengal. • There is staged sediment supply from the G-B Rivers into the Bay of Bengal. • Heavy sediment supply of the G-B Rivers was affected by climate change. • The channels developed on the Bengal Fan are important in the sediment transport process. • Sediment source change at ∼26 ka may be related to conversion of deep-water currents. [ABSTRACT FROM AUTHOR]

Petrographic classifications of sand and sandstone proposed more than half a century ago are still in use, although they were formulated at a time when depositional and post-depositional sedimentary processes were poorly understood, and before the relationships between tectonics and sedimentation could be interpreted in modern plate-tectonic terms. As a consequence, too many scientific articles and technical reports are still encumbered with obsolete concepts, graphical tools, and ambiguous terminology that make sediment descriptions awkward and misleading. A renovation that treasures the legacy of the pioneers is required. The descriptive petrographic classification of sand and sandstone proposed in this paper is based on the quasi-universally used Gazzi-Dickinson point-counting method, and simply translates into words ternary compositions of quartz, feldspar, and lithic fragments without introducing any new names. The classic QFL plot is subdivided into 15 fields - labelled by adjectives introduced long ago by K.A.W. Crook and endorsed by W.R. Dickinson and more recently by G.J. Weltje - which reflect relative abundances of the three main framework components (provided they exceed 10%QFL). According to standard use, the less abundant component goes first, the more abundant last (e.g., litho-feldspatho-quartzose composition translates into Q > F > L > 10%QFL). For lithic-rich sand and sandstone, information on the prevailing rock fragment type can be added by an additional free adjective (e.g., metamorphiclastic, carbonaticlastic), as proposed long ago by R.V. Ingersoll. For lithic-poor feldspatho-quartzose and quartzose sand and sandstone, further formal subdivisions are proposed based on the Q/F ratio, thus reaching a total of 18 compositional fields overall. Modern sand known to be derived from different source rocks and found in major world's rivers, deserts, and deep-sea fans fits in the pigeonholes defined by the relative abundance of quartz, feldspar, and lithic fragments. The aim of this classification is to restore directness in sandstone petrology, and to avoid ambiguities generated in the past by making reference to badly defined archetypes, such as greywacke or arkose, thus confusing petrographic composition with subjective considerations about plate-tectonic setting, texture, hydraulic behaviour, mechanical durability, or chemical durability in the illusion that a classification could be genetic at the same time as descriptive. [ABSTRACT FROM AUTHOR]

Abstract Major and trace elements of sediments from two gravity cores (10YDY09 and 12I712) in the northeastern Indian Ocean have been analyzed for sediment provenance and the relationship of the sediments with climate change since 50 ka. The rare earth element (REE) compositions were analyzed, and the sediment contributions were estimated for the major potential sources, including the Ganges-Brahmaputra (G-B), Godavari-Krishna (G-K) and Mahanadi Rivers. Our results showed that the sediments in the study area were a mixture of sediments discharged from the above three rivers. The sediment contribution of the G-K Rivers increased notably during the Holocene when the rainfall increased, which may be caused by the strengthening of the East Indian Coastal Current (EICC) and the resulting large amounts of sediments supplied by the G-K Rivers. The higher sediment contribution from the G-B Rivers demonstrated the role of the Active Channel in transporting sediments to the distal Bengal Fan. During the last glacial maximum (LGM), especially in the late period, the Indian summer monsoon weakened, but the winter monsoon strengthened, resulting in a decrease in chemical weathering and elemental enrichment in the northeastern Indian Ocean. Conversely, when the rainfall was low, the chemical weathering strengthened and K 2 O/TiO 2 ratios were lowered due to the longer weathering time and resulting sediment potassium loss. However, when the sea level reached a certain height during the Holocene, the fluvial sediments could not easily enter deep-water environments through submarine channels, which were well developed in the Bengal Fan. Highlights • The major and trace elements of two cores were analyzed for sediment provenance. • The role of the Active Channel in the formation of the Bengal Fan was discussed. • The influence of the sea level fluctuations and rainfall changes over the past 50 ka was evaluated. • Coastal currents driven by the monsoon winds are key forces in sediment transport. [ABSTRACT FROM AUTHOR]

Objective: A concentration of airborne bacteria generated from swine houses is recognized to be relatively higher than other work places and it is essential to optimally manage it to prevent farmers' respiratory diseases. This study was conducted to assess the distribution characteristics of airborne bacteria in swine houses located at South Korea. Methods: A total 27 pig buildings of the enclosed type operated with mechanical ventilation system by a side wall fan and deep-pit manure system with slats were surveyed. Air samples were collected at 1.0 m above the middle floor in pig housing room. A six-stage viable particulate cascade impactor was used to identify the distribution of the sizes of particles in diameter. Results: Seasonal mean levels of airborne bacteria in the housing rooms of gestation/farrowing pigs, nursery pigs and growing/fattening pigs were 3,428(±1,244) colony forming unit (cfu)/m3, 8,325(±3,209) cfu/m, and 13,254(±6,108) cfu/m3 for spring,9,824(±2,157) cfu/m3, 18,254(±5,166) cfu/m3, and 24,088(±9,274) cfu/m3 for summer,1,707(±957) cfu/m3, 4,258 (±1,438) cfu/m3, and 8,254(±2,416) cfu/m3 for autumn,and 2,322(±1,352) cfu/m3, 6,124(±1,527) cfu/m3 and 12,470(±4,869) cfu/m3 for winter, respectively. Conclusion: Concentrations of airborne bacteria according to pig housing type were highest in growing/fattening housing room followed by nursery housing room and gestation/farrowing housing room. In terms of seasonal aspect, the pig building showed the highest levels of airborne bacteria in summer followed by spring, winter and autumn. The respirable airborne bacteria which are ranged between 0.6 and 4.7 μm accounted for approximately 60% compared to total airborne bacteria regardless of pig housing type. [ABSTRACT FROM AUTHOR]

In recent years, enriched hydrocarbon reservoirs have been largely founded in the Lower Triassic Baikouquan Formation, in the Mahu Depression of Junggar basin, northwestern China. Accordingly, the sedimentologic complexity of associated deposits has been extensively studied, though most of them focused on local oil‐producing fields separately. In this research, a detailed sedimentary study of the entire Mahu Depression has been conducted, which include several aspects of sedimentary characteristics, sediment provenance, evolution, and controls of the coarse‐grained fan‐delta system. According to facies features recognized from cores, thin sections, well logs, and seismic data, three sedimentary facies associations were identified: upper fan‐delta plain, lower fan‐delta plain, and fan‐delta front. Furthermore, four depositional systems (Xiazijie, Haungyangquan, Karamay, and Xiayan fan‐delta) around the Mahu Depression were recognized by the distribution of heavy mineral assemblages and change of ZTR index (percentage of Zircon, Tourmaline, and Rutile in the total transparent heavy mineral assemblage). Based on the analysis of facies and sediment provenance, the temporal and spatial distribution of the fan‐delta system were reconstructed associated with the variation of net/gross ratio. As characterized by decreasing‐upward of net/gross ratios and fining‐upward trend of grain size, the evolution of the fan‐delta succession showed an overall retreating pattern which was mainly controlled by lake level rising and rapid tectonic subsidence. Within the retreating pattern, hydrocarbons were trapped in the middle deposits with reservoir space produced by fan‐delta front and lower fan‐delta plain, which were encased between the top transgressive lacustrine mudstones and the bottom debris‐flow deposits produced by upper fan‐delta plain. These findings of the research throw light on the phenomena that the stratigraphy trap for hydrocarbon accumulation could be constructed by retreating, coarse‐grained fan‐delta systems. [ABSTRACT FROM AUTHOR]

The effects of changes in slope gradient on deposition processes and architecture have been investigated in different deep-sea systems both in modern and ancient environments. However, the impact of subtle gradient changes (< 0.3 ∘) on sedimentary processes along deep-sea fans still needs to be clarified. The Ogooue Fan, located in the northeastern part of the Gulf of Guinea, extends over more than 550 km westwards of the Gabonese shelf and passes through the Cameroon volcanic line. Here, we present the first study of acoustic data (multibeam echosounder and 3.5 kHz, very high-resolution seismic data) and piston cores covering the deep-sea part of this West African system. This study documents the architecture and sedimentary facies distribution along the fan. Detailed mapping of near-seafloor seismic-reflection data reveals the influence of subtle slope gradient changes (< 0.2 ∘) along the fan morphology. The overall system corresponds to a well-developed deep-sea fan, fed by the Ogooue River sedimentary load, with tributary canyons, distributary channel–levee complexes and lobe elements. However, variations in the slope gradient due to inherited salt-related structures and the presence of several seamounts, including volcanic islands, result in a topographically complex slope profile including several ramps and steps. In particular, turbidity currents derived from the Gabonese shelf deposit cross several interconnected intra-slope basins located on the low gradient segments of the margin (< 0.3 ∘). On a higher gradient segment of the slope (0.6 ∘), a large mid-system valley developed connecting an intermediate sedimentary basin to the more distal lobe area. Distribution and thickness of turbidite sands is highly variable along the system. However, turbidite sands are preferentially deposited on the floor of the channel and the most proximal depositional areas. Core description indicates that the upper parts of the turbidity flows, mainly composed of fine-grained sediments, are found in the most distal depocenters. [ABSTRACT FROM AUTHOR]

New bulk sediment Sr and Nd isotope data, coupled with U–Pb dating of detrital zircon grains from sediment cored by the International Ocean Discovery Program in the Arabian Sea, allow the reconstruction of erosion in the Indus catchment since ∼17 Ma. Increasing εNd values from 17 to 9.5 Ma imply relatively more erosion from the Karakoram and Kohistan, likely linked to slip on the Karakoram Fault and compression in the southern and eastern Karakoram. After a period of relative stability from 9.5 to 5.7 Ma, there is a long-term decrease in εNd values that corresponds with increasing relative abundance of >300 Ma zircon grains that are most common in Himalayan bedrocks. The continuous presence of abundant Himalayan zircons precludes large-scale drainage capture as the cause of decreasing εNd values in the submarine fan. Although the initial increase in Lesser Himalaya-derived 1500–2300 Ma zircons after 8.3 Ma is consistent with earlier records from the foreland basin, the much greater rise after 1.9 Ma has not previously been recognized and suggests that widespread unroofing of the Crystalline Lesser Himalaya and to a lesser extent Nanga Parbat did not occur until after 1.9 Ma. Because regional erosion increased in the Pleistocene compared to the Pliocene, the relative increase in erosion from the Lesser Himalaya does not reflect slowing erosion in the Karakoram and Greater Himalaya. No simple links can be made between erosion and the development of the South Asian Monsoon, implying a largely tectonic control on Lesser Himalayan unroofing. [ABSTRACT FROM AUTHOR]

Abstract Ice-contact deposits emplaced by Late Paleozoic Ice Age (LPIA) glaciers are rarely exposed due to a low degree of preservation and their capping by thick glaciomarine deglaciation sequences. In this paper, we present new data on glacial cyclicity, relative age constraints and paleoice flow interpretations for an ice-contact succession of the lowermost Itararé Group in eastern Paraná Basin (Brazil). The 80 m-thick ice-contact complex rests over the Itararé Group basal unconformity and comprises four stacked informal stratigraphic units regarded as the depositional/deformational record of three ice lobes advance/retreat cycles. Glacial cycle 1 comprises a sheet of massive diamictite resting on striated pavements carved on Devonian sandstones and topped by grooved/fluted surfaces, which indicate subglacial emplacement from a northward flowing ice lobe. The glacial cycle 2 succession was deposited in a proglacial to ice-marginal marine setting and subsequently deformed due to minor ice margin fluctuations of a westward/southwestward flowing grounded ice lobe. Glacial cycle 3 is interpreted as a thick overridden push moraine composed of grounding-line fan deposits capped by a subglacial diamictite emplaced by grounded ice advancing northwestward. A middle Visean-early Serpukhovian palynomorph assemblage was recorded in cycle two deposits, representing the oldest late Paleozoic glacial rocks in the Paraná Basin. The ice-contact complex elucidates multiple waxing and waning phases of the Windhoek Ice Sheet onto the eastern margin of the Paraná Basin during the Mississippian-Early Pennsylvanian, demonstrating that ice sheets of the early stages of the LPIA were also present in the Brazilian-African domain of southwestern Gondwana. Highlights • 3 glacial cycles with variable ice lobe kinematics are defined for an ice-contact complex in the lowermost Itararé Group. • The basal age of the Itararé Group is older than previously interpreted ranging from the middle Visean. • Ice sheets covered the west-central domain of Gondwana during the Mississippian. [ABSTRACT FROM AUTHOR]

Abstract The Mackenzie River flows into the Arctic Ocean via a complex network of channels, creating a plume that dominates water properties over the southern Beaufort Sea shelf. Observations of temperature, salinity, water level elevations and currents collected in August 2007 and August 2010 are used to investigate the circulation and structure of the river plume, during periods with predominantly easterly/offshore winds. The measurements were collected from instrument platforms in a river channel, in shallow water of 2–6 m depth (10–25 km from the coastline), from a research vessel, and from satellites. The observations indicate that moderate atmospheric forcing, including sea level pressure changes of 1–2 kPa and easterly alongshore wind stress (< 0.1 Nm − 2 ), is sufficient to induce a 0.2–0.3 m set-down of the mean water level and surface currents up to 0.6 ms − 1 . A theoretical model of the water level at the delta suggests that local wind stress is the primary driver of sea level variability. The observations show that the region is stratified with a shallow river surface plume at the surface, and winds primarily cause offshore transport of the plume up to 30 km per day. Winds also cause separation of the plume from the coast and onshore transport of shelf water near the bottom that induces local changes in temperature of up to 12 o C. River water is the primary source of heat, and therefore sea surface temperatures in the coastal ocean are strongly determined by the inflowing freshwater temperatures. The coastal plume responds to atmospheric forcing over timescales of less than 1 day, leading to rapid development of strong currents and large fluctuations in water mass properties in the shallow region across the submarine delta. Highlights • In situ and remotely sensed observations of an Arctic river plume were collected. • Wind-driven sea level fluctuations and strong surface currents were observed. • The coastal region is strongly stratified with a shallow river plume at the surface. • Riverine heat flux dominates the heat budget of the continental shelf. • The plume responds to atmospheric forcing over timescales of less than a day. [ABSTRACT FROM AUTHOR]

Sandy sedimentary rocks rich in detrital matrix (>10% silt/clay) have long been recognized in the ancient sedimentary record, and nowhere more commonly than in deep‐marine turbidite systems. Despite this, their depositional mechanisms remain poorly understood, in part because these rocks, which are enriched in fine‐grained sediment, are often poorly exposed in outcrop or are confined to observation in core. Matrix‐rich strata in the Neoproterozoic Windermere Supergroup, in contrast, are very well‐exposed and show systematic changes in lithofacies over distances of several tens to a few hundreds of metres along‐strike. Notably, these strata are observed in both basin floor and continental slope deposits, suggesting that their occurrence and systematic lithological arrangement is related to mechanistic, rather than palaeogeographic, controls. Specifically, the facies transect consists of structureless, clayey sandstone that transforms along‐strike to a two‐layer deposit with the development of an upper, planar‐based, markedly more matrix‐rich layer. Further along‐strike, the basal clayey sandstone thins and eventually pinches out, leaving only the (upper) sandy claystone layer, which in turn thins along‐strike and then pinches out. These systematic changes in lithology, but more specifically the distribution of clay, is interpreted to form a depositional continuum related to particle settling in a horizontally advecting, high concentration particle suspension formed along the margins of an avulsion‐related high‐energy turbulent suspension. [ABSTRACT FROM AUTHOR]

Deltas are important coastal sediment accumulation zones in both marine and lacustrine settings. However, currents derived from tides, waves or rivers can transfer that sediment into distal, deep environments, connecting terrestrial and deep marine depozones. The sediment transfer system of the Rhone River in Lake Geneva is composed of a sublacustrine delta, a deeply incised canyon and a distal lobe, which resembles, at a smaller scale, deep‐sea fan systems fed by high discharge rivers. From the comparison of two bathymetric datasets, collected in 1891 and 2014, a sediment budget was calculated for eastern Lake Geneva, based on which sediment distribution patterns were defined. During the past 125 years, sediment deposition occurred mostly in three high sedimentation rate areas: the proximal delta front, the canyon‐levée system and the distal lobe. Mean sedimentation rates in these areas vary from 0·0246 m year−1 (distal lobe) to 0·0737 m year−1 (delta front). Although the delta front–levées–distal lobe complex only comprises 17·0% of the analysed area, it stored 74·9% of the total deposited sediment. Results show that 52·5% of the total sediment stored in this complex was transported toward distal locations through the sublacustrine canyon. Namely, the canyon–levée complex stored 15·9% of the total sediment, while 36·6% was deposited in the distal lobe. The results thus show that in deltaic systems where density currents can occur regularly, a significant proportion of riverine sediment input may be transferred to the canyon‐lobe systems leading to important distal sediment accumulation zones. [ABSTRACT FROM AUTHOR]

Abstract The Ledong Submarine Fan in the western Qiongdongnan Basin runs parallel to the continental slope, with an area of over 10,000 km2 and maximum thickness of greater than 2000 m. Using bulk rare earth element (REE) compositions of the sediments and detrital zircon U-Pb age data, we analysed the provenance of the Ledong Submarine Fan and its regional tectonic implications. The zircon grains in the Ledong Submarine Fan show a wide range of shapes, from prismatic crystals to oval grains with mostly rounded corners, indicating the long transport distance of these zircon grains prior to deposition. The zircon ages have a wide range from 27 to 3006 Ma, with five major age peaks at ca. 27 Ma, 88 Ma, 256 Ma, 415 Ma and 785 Ma, along with a number of subordinate age peaks at ca. 1024 Ma, 1376 Ma, 1879 Ma and 2374 Ma. These age distribution patterns are similar to those from the Red River at Yen Bai. The total REE content range is between 87.72 and 210.38 mg/g in the Ledong Submarine Fan. The chondrite-normalized REE patterns show light REE (LREE) enrichment and weakly negative Eu anomalies, which are similar to those in the Red River at Hanoi. The evidence from zircon U-Pb ages and REE geochemistry indicates that the provenance of the Ledong Submarine Fan is the Red River System. The development of the Ledong Submarine Fan indicates that a rapid subsidence occurred in the western Qiongdongnan Basin during the late Miocene, and the strike slip reversal of the Red River Fault from sinistral to dextral motion was the key factor that induced gravity flow to form the Ledong Submarine Fan. Highlights • Detrital zircons and REE from the sediments in the continental slope-parallel Ledong Submarine Fan were examined. • The source of the Ledong Submarine Fan sediments was from the Red River System. • The development of the Ledong Submarine Fan has implication for the tectonic activity of the Red River Fault. [ABSTRACT FROM AUTHOR]

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Fault-scarp related fan deltas developed in tilted half grabens in NE Greenland during late Jurassic—early Cretaceous rifting. This study documents ichnological and sedimentological characteristics of the Lower Cretaceous interval of a submarine fan-delta succession (Palnatokes Bjerg Formation, Wollaston Forland), which represents a time of waning rift activity and transgression. For this purpose, two variably exposed ca. 150 m-thick sections were studied ∼10 km from the coeval fault scarp, near the axis of the most proximal fault block. Moreover, an additional ∼20 m thick coeval succession was studied in the next fault block ∼20 km from the coastline defining fault. The results indicate deposition on the basin floor, in the distal fan and in a mid-fan channel-overbank/splay complex of a subaqueous fan delta. The deposits are characterized mainly by various facies of high and low density turbidity currents, hybrid event beds, and transitional flow facies that grade upward into sediment starved basinal mudstones. The ichnological pattern recorded in these strata is strongly mixed, frequently containing elements of the impoverished Skolithos, Cruziana, Zoophycos ichnofacies, and more rarely of the Nereites ichnofacies. Characteristic features also include suites dominated by infaunal locomotion and feeding trails (including the "Curvolithus suite") and the common occurrence of crustacean burrows. The results are indicative of a depositional system resembling a fjord-side delta that differs sedimentologically and ichnologically from many other gravity-flow systems of similar grain-size caliber. The ichnological pattern recorded in these strata is potentially a characteristic feature of the subaqueous fan-deltas in comparable settings, reflecting the distinct basin physiography with an abrupt change in bathymetry, a narrow basin geometry, and environmental stress resulting from unstable physical conditions. The counter slope of the rotated fault block may explain the common signs of flow concentration and abrupt fan termination. [ABSTRACT FROM AUTHOR]

Abstract Long marine sequences deposited in the Arabian Sea are suitable to study the orbital sensitivity of sediment dynamics from a source-to-sink perspective. The clay mineralogy and Sr Nd isotopic compositions have been analyzed for the detrital fraction of sediments from IODP Site U1457 located in the Laxmi basin, eastern Arabian Sea to constrain the sediment sources and reconstruct a high-resolution record of sediment export to the Indus deep-sea fan over the past 600 kyr. The 87Sr/86Sr ratio (varying from 0.7154 to 0.7255) and εNd (varying from −12.9 to −9.5) imply a mixing of sediments derived from not only the Indus River but also the rivers draining the Deccan Traps. The variations in the smectite/(illite + chlorite) ratio combined with Sr Nd isotopes permit the reconstruction of past changes in the relative proportions of sediments derived from the Indus River (mainly illite, chlorite and kaolinite) and the Deccan Traps (smectite). The wavelet and cross-spectral analyses further reveal that sediment transport to the eastern Arabian Sea since 600 kyr is mainly dominated by sea-level variations in the eccentricity (100-kyr) band, while the Indian summer monsoon might contribute moderately to the precession (23-kyr) band. The εNd and turbidite frequency indicate that more turbidite events are associated with Indus River-sourced sediments at IODP Site U1457 during sea-level lowstands, which might reflect a reconnection of deep-sea channels to the Indus River mouth and/or reworking of previously deposited Indus River sediments located northward. Highlights • First high resolution clay mineral record from IODP Site U1457 since 600 kyr. • Deccan Traps and Indus River are the main sediment sources for the Laxmi basin. • Clay mineralogy variations from IODP Site U1457 were controlled by sea-level variations. • Turbidite events are associated with Indus River-sourced sediments at IODP Site U1457. [ABSTRACT FROM AUTHOR]

Abstract The mechanisms governing the development of deep-sea fans is a matter of debate and their understanding at Milankovitch and millenial time-scales is challenged by complex architectures and the lack of material suitable for establishing reliable chronostratigraphies. Based on a detailed investigation of the emplacement of channel-levee-lobe systems and their successive bifurcations and seaward-landward migrations (Picot et al., 2016), we present for the last 210 ka a detailed chronostratigraphic framework of the migration pattern based mainly on radiocarcarbon dating of channels and lobes abandonment or initiation. The comparison of architectural cycles to proxies of external factors (sea-level and climate) suggest that sea-level changes have minor impacts on the architectural evolution of the Congo Fan. In contrast, comparison with climate and environmental proxies (West African monsoon, pollen grain assemblages, Kaolinite/Smectite) evidences a major impact on the timing of the development of the architectural pattern, at least for the last 38 kyr. A general scheme of the growth pattern of the Congo Fan in link with climate evolution is proposed: the stacking pattern of the Congo Fan responds to humidity/aridity cycles that generate successive progradation and retrogradation of avulsion points. These climate changes are under the control of the West African monsoon which, by controlling the rainfall and vegetation on the watershed, ultimately impacts the composition and volume of the sediment source and the transport capacity of gravity flow generated in the canyon and flowing in the turbiditic channels. [ABSTRACT FROM AUTHOR]

Exploration of Martian surface and the crater deposition has recently attracted scientific community. We hypothesized the existence of momentous topographic features of different origin on the Martian surface. It was observed that Gale Crater has a thick sediment deposition mainly of fluvial and aeolian origin. This study has utilized spatially referenced topographic dataset Context Camera images acquired from Mars reconnaissance orbiter for exploring the geomorphic processes and topography of Gale Crater. A base map was prepared by mosaicking all imagesfor preparing geomorphologic map of the crater. Surface map of the topography of the Crater was prepared using Mars Orbiter Laser Altimeter (MOLA) data. HiRISE images were used to examine the identified geomorphic features. Results revealed that the presence of both fluvial and aeolian processes and their respective associated landforms in the Crater. Depositional landforms such as alluvial fan, inverted channel and mound and erosional landform namely canyons were distinctly identified on the image. Yardangs produced by erosional and ripple and dunes formed by the depositional work of wind were also identified in the Crater. The fluvial channel, inverted channels and fan shaped deposits further signifies ongoing aqueous activity on the Gale Crater. Sinuous ridges are the common features present on the floor of Crater. Rock particles, sand and silt in the crater were found to have been transported and deposited by flowing water on its floor. Presence of different sedimentary structures and valley revealed ancient sedimentary deposition due to water action. Significant ejecta morphologies were also identified on Martian surface. Our study confirms the previous studies that presence of H2O sub surface volatiles. Concentrations of volatiles have produced double layer ejecta morphology. The concept and findings of this study will escalate knowledge about the surface features on Gale Crater. However, more coherent investigation is needed for modelling and understanding the processes and landforms of the crater. Context Camera (CTX) and High-Resolution Imaging Science Experiment (HiRISE) images have proved useful for geomorphic and topographic mapping of the Mars planet. The dataset used in this study can be accessed on Mars Orbital Data Explorer (https://ode.rsl.wustl.edu/mars/indexproductsearch.aspx). [ABSTRACT FROM AUTHOR]

Submarine fans are archives of Earth‐surface processes and change, recording information about the turbidity currents that construct and sculpt them. The volume and recurrence of turbidity currents are of great interest for geohazard assessment, source‐to‐sink modelling, and hydrocarbon reservoir characterization. Yet, such dynamics are poorly constrained. This study integrates data from four Quaternary submarine fans to reconstruct the volume and recurrence of the formative turbidity currents. Calculated event volumes vary over four orders of magnitude (105 to 109 m3), whereas recurrence intervals vary less, from 50 to 650 years. The calculated turbidity‐current‐event volume magnitudes appear to be related to slope position and basin confinement. Intraslope‐fan deposits have small event volumes (ca 106 m3) while ponded‐fan deposits have very large event volumes (108 to 109 m3). Deposits in non‐ponded, base‐of‐slope environments have intermediate values (107 to 108 m3). Sediment bypass in intraslope settings and flow trapping in ponded basins likely account for these differences. There seems to be no clear relationship between event recurrence and basin confinement. Weak scaling exists between event volume and source‐area characteristics, but sediment storage in fluvial and/or intraslope transfer zones likely complicates these relationships. The methodology and results presented here are also applied to reconstruct the time of deposition of ancient submarine‐fan deposits of the Tanqua Karoo basin, South Africa. The volume and recurrence of submarine‐fan‐building turbidity currents form intermediate values between values measured in submarine canyons and channels (<105 m3 and <101 years) and on abyssal plains (>108 m3 and >103 years), indicating that small, frequent flows originating in submarine canyons often die out prior to reaching the fan, while rare and very large flows mostly bypass the fan and deposit sediment on the abyssal plain. This partitioning of flow volume and recurrence along the submarine sediment‐routing system provides valuable insights for better constraining geohazards, hydrocarbon resources and the completeness of the stratigraphic record. We provide a methodology to estimate the volume and recurrence of turbidity currents that deliver sediment to submarine fans. We apply this method to four modern fan systems from around the world and also to ancient fan deposits. Finally, we compare these event volume and frequency values to those derived from submarine canyons and abyssal plains, providing valuable data for geohazard assessment. [ABSTRACT FROM AUTHOR]