bluuebunny/crossref_metadata_2025_split huggingface dataset:
‘SLABBER’: a useful device for subsampling box cores
Authors: BENGGIO BRADFORD L. , NELSEN TERRY A. 
Published: June 2006

ABSTRACT The ‘SLABBER’, a plexiglass device designed for subsampling box cores, was used at sea with excellent results. The SLABBER allowed visual inspection of any existing sedimentary features, and also provided storage, when necessary for subsamples. When the features were present, X‐radiography of the SLABBER subsamples clearly showed sediment layering, evidence of bioturbation and orientation of shell material, all with apparent minimal disturbance of these structures.
Geomorphic evolution and stratigraphy of Price and Capers Inlets, South Carolina
Authors: TYE ROBERT S. 
Published: June 2006

ABSTRACTA three‐dimensional model for a tidal inlet‐barrier island depositional system was constructed through examination of 37 vibracores and 10 auger drill holes on Capers and Dewees Islands, South Carolina. Two cycles of southerly inlet migration and subsequent abandonment resulted in beach ridge truncation on the northern ends of both barriers. Historical evidence indicates that these tidal inlets migrated 1.5 km to the south owing to a dominant north‐south longshore transport direction. The hydraulic inefficiency of these over‐extended inlet channels caused shorter, more northerly‐oriented channels to breach through the ebbtidal deltas. After inlet reorientation, large wave‐formed swash bars migrated landward closing former inlet channels. Weakened tidal currents through the abandoned channels permitted clay plugs to form thick impermeable seals over active channel‐fill sand and shell.Price and Capers Inlets formed during the onset of the Holocene transgression following submergence of the ancestral Plio‐Pleistocene Santee River drainage system. Coarse, poorly sorted inlet‐deposited sand disconformably overlies Pleistocene estuarine clay and is capped by a dense clay plug. Shoreline reorientation and landward retreat of a primary barrier island chain occurred between the first and second cycles of inlet‐channel migration and abandonment. Beach ridges prograded seaward over the first inlet sequence. A second cycle of inlet migration truncated the northernmost portion of these beach ridges and scoured into the clay plug of the earlier inlet deposit. Abandonment of this channel resulted in deposition of a second abandoned inlet‐channel clay plug. Abandoned tidal inlet channels exhibit U‐shaped strike and crescentic‐ to wedge‐shaped dip geometries. Basal, poorly sorted inlet sands are sealed beneath impermeable, abandoned‐channel silt and clay, washover deposits, and salt marsh. Multiple episodes of inlet migration and abandonment during a rising sea‐level deposited stacked inlet‐fill sequences within the barrier islands.The resultant stratigraphy consists of interlayered, fining‐upward, active inlet‐fill sand overlain by thicker abandoned inlet‐fill clay plugs. These clay plugs form impermeable zones between adjacent barrier island sand bodies. Shoreline transgression would remove the uppermost barrier island deposits, sealing the inlet‐fill sequences between Pleistocene estuarine clay and shoreface to shelf silt and clay.
Organic films on particulate matter in surface waters off eastern Asia
Authors: EMERY K. O. , JOHNS IAN A. , HONJO SUSUMU 
Published: June 2006

ABSTRACTSEM examination of suspended material collected by filtration from samples of surface waters over continental shelves and deeper areas off eastern Asia reveals the presence of irregular organic films that are longer, cover more filter area, and have more tapered edges in samples from nearshore than offshore regions. Associated diatoms include species diagnostic of coastal environments. Films and coastal diatoms are most abundant in waters above continental shelves where river discharges cause the waters to be more dilute than 33.5‰ salinity. Farther from shore, both films and skeletal elements are broken and partly dissolved. Skeletal elements, faecal matter, and other debris are trapped or adhere to the films, which therefore provide a concentrated food source for small organisms beyond nearshore regions of high primary productivity. The films contribute an unknown percentage of the total organic matter that reaches bottom sediments.
Lateritization and ground water alteration phenomena in the Triassic Budra Formation, south‐western Sinai
Authors: GOLDBERY R. , BEYTH M. 
Published: June 2006

ABSTRACTField and laboratory investigations of the Triassic Budra Formation of Wadi Budra, south‐west Sinai, have demonstrated the existence of surface pedogenic laterites developed within‘overbank facies’of fluviatile sediments during times of hiatus. The laterite profiles, up to 7 m thick, comprise a zone of high‐iron concentrations (21.47–73.17%) which includes a concretionary unit and either overlies a zone of slightly mottled host rock or rests directly upon unaltered sandstone; a pallid zone is noticeably absent. The primary depositional horizontal fabric of the finely laminated sediments of the‘overbank facies’ has strongly influenced the final fabric of the laterite. The pronounced alternations of iron‐rich pisolitic and iron‐deficient laminae highlight the influence of inherent fabric (primary bedding) on pedogenesis. The micromorphology of the laterites is characterized by bimasepic plasmic fabrics, abundant elongate voids partially infilled with cryptocrystalline kaolinite and an abundance of randomly oriented skew planes. Illuviation of clay minerals to considerable depths is evident. Sesquioxidic and kaolinitic glaebules, concentrated within the concretionary units of the laterite have a flattened ellipsoidal shape and occur as both massive and concentrically structural varieties.At Gebel Mussaba Salama to the north, zoned iron mineralization occurs at various levels within the fluviatile sandstones which underlie the‘overbank facies’. This is interpreted as being a non‐pedogenic, ground water alteration phenomenon induced by a rising water table within the buried alluvial channels. Iron mineralization, probably records minor fluctuations of the water table during standstill periods.Lateritization in the Triassic Budra Formation provides important evidence that the widely recorded late Triassic lateritization and bauxitization event of the neighbouring East Mediterranean countries, extended south to the continental areas bordering the Tethyan Ocean.
Sedimentology of the Minette oolitic ironstones of Luxembourg and Lorraine: a Jurassic subtidal sandwave complex
Authors: TEYSSEN T. A. L. 
Published: June 2006

ABSTRACTThe oolitic ironstones of the Minette were deposited during Toarcian/Aalenian times in a nearshore environment of the Paris Basin. The sedimentary sequence comprises up to 13 coarsening upward depositional cycles. The development of the cycles and different facies types are described. The iron ooids accumulated in a subtidal environment under the effects of tidal currents. Sand waves, which form an important part of the Minette sediments, were deposited under both time‐velocity symmetrical and time‐velocity asymmetrical tides. From the study of their internal structures the time‐velocity patterns of the currents, current speeds (up to 0±9m s−1) and net transport rates have been estimated (29 g m−1 s−1 in the case of large‐scale sand waves controlled by time‐velocity symmetrical tides). Sand wave heights and calculated near‐bed current speeds suggest a mesotidal regime. Sedimentary facies include large‐scale and waves, subtidal shoals with channels and an offshore muddy shelf. Conclusions as to bathymetry are drawn from ichnofaunal associations and from the study of wave ripple marks. Finally a depositional model of the Minette iron formation is proposed which may be applicable to other oolitic ironstones.
A regressive coastal sequence from the Upper Eocene of Hampshire, southern England
Authors: PLINT A. G. 
Published: June 2006

ABSTRACTThe Lower Headon and Upper Barton Beds of Hampshire, southern England, consist of fine sands, silts and clays, often fossiliferous, with lignitic and carbonate horizons. They accumulated in a coastal environment following deposition of the marine Lower and Middle Barton Beds. A variety of distinctive facies can be defined on faunal and lithological grounds, and these permit palaeoenvironments to be defined with some precision. Littoral marine, barrier island shoreface, storm washover and barrier flat, brackish lagoon, distributary channel and floodplain lake environments are recognized. The evidence suggests that a barrier island or spit developed offshore, enclosing a sheltered inshore region of lagoons in which deposition of relatively fine‐grained sediments took place. Lagoonal sediments show a general trend towards reduction of salinity with time. With the eventual exclusion of marine influence, the area underwent a gradual transition to river‐dominated sedimentation in shallow flood‐plain lakes. While the sequence as a whole shows a progressive reduction in salinity, several brief periods of increased salinity are recognized and these reflect the very low topography of the region and its susceptibility to marine incursion.
Bedload stresses and sediment transport theory—a correction
Authors: LEEDER MICHAEL R. 
Published: June 2006

ABSTRACTA previous proposal (Leeder, 1977) to test the magnitude of the solid‐transmitted stresses due to bedload transport failed to confirm Bagnold's theory because the applied fluid stress contribution was not corrected for sidewall drag. Once this correction is made there is a reasonable correspondence of theory and experiment.
Variations in wind velocity and sand transport on the windward flanks of desert sand dunes
Authors: LANCASTER N. 
Published: June 2006

ABSTRACTThe magnitudes of increases in wind velocity, or speed‐up factors, have been measured on the windward flanks of transverse and linear dunes of varying height. On transverse dunes, velocity speed‐up varied with dune shape and height. For linear dunes, speed‐up factors varied principally with wind direction relative to the dune, with dune shape and dune height. The main effect of velocity speed‐up on the windward flanks of dunes is to increase potential sand transport rates considerably in crestal areas. This is greatest for large dunes, with winds of moderate velocity blowing at a large angle to the dune. Changing ratios of base to crest sand‐transport rates on transverse dunes tend to reduce dune steepness as overall wind velocities increase. On linear dunes, the tendency for crestal lowering is counteracted by deposition in this area when winds reverse in a bi‐directional wind regime.
Platform and off‐platform carbonates of the Upper Cambrian of western Maryland, U.S.A.
Authors: DEMICCO ROBERT V. 
Published: June 2006

ABSTRACTUpper Cambrian carbonates in western Maryland are comprised of platform facies (Conococheague Limestone) west of South Mountain and basin facies (Frederick Limestone) east of South Mountain. Conocheague platform carbonates contain interbedded non‐cyclic and cyclic facies. Non‐cyclic facies consist of cross‐stratified grainstones, thrombolitic bioherms, and graded, thin‐bedded dolostones. These were deposited in shallow, subtidal shelf lagoons. Cyclic facies are composed of repeated sequences of cross‐stratified grainstone; ribbon‐rock; wavy, prism‐cracked laminite; and planar laminated dolostone. The cyclic facies are shallowing‐upward cycles produced by lateral progradation of tidal flats over shallow, nearshore subtidal environments. Cyclic and non‐cyclic facies are interbedded in the Conococheague in a layer cake fashion, but no higher‐order cyclicity can be found.The Frederick Limestone is dominated by monotonously thick sequences of graded, thin‐bedded limestones, interbedded with massive peloidal grainstones and beds of breccia up to 10 m thick in the lower Frederick. The breccias contain transported megaclasts of Epiphyton‐Girvanella boundstones. The basal Frederick was deposited in a slope‐to‐basinal setting east of a rimmed shelf. An Epiphyton‐Girvanella marginal reef along the shelf edge was the source of the blocks in the breccias. The upper Frederick Limestone formed on a carbonate ramp.
Characteristics of two Pleistocene channel‐fill deposits and their implication on the interpretation of megasequences in ancient sediments
Authors: LAJOIE JEAN , ST‐ONGE DENIS A. 
Published: June 2006

ABSTRACTTwo Pleistocene channel fills located in two different geological settings, on Guadeloupe in the lesser Antilles and along the Coppermine River in the Northwest Territories of Canada, have different clast compositions, scale, and origin of fragmentation but have similar depositional characteristics. Massive bedding or absence of structures caused by traction, sharp non‐erosive contacts, reverse coarse‐tail grading, matrix‐supported clasts together indicate a debris‐flow mechanism in which mixtures of fine and coarse sediments moved downslope by laminar flow. Field evidence suggests subaqueous deposition for both deposits. Both bed thickness (BTh)/maximum grain size (MGS) ratios and correlations appear characteristic of subaqueous masses capable of flowing on slopes less than 1°.The two channel fills have random BTh and MGS variations, they do not thin and fine up‐section. It is suggested that fills originating from laminar mass transport could normally have random BTh and MGS up‐section variations. In flysch and volcaniclastic sequences, where coarse sediments interpreted as laminar flow deposits are common, up‐section BTh and MGS variations may result from processes related to source, slope, and flow characteristics rather than from the environment in which the sediments accumulate (channel).
Seasonal succession and microlamina formation in a meromictic lake displaying varved sediments
Authors: DICKMAN MIKE 
Published: June 2006

ABSTRACTIn a small meromictic lake near Toronto, Canada, a mass mortality of photosynthetic bacteria followed the ventilation of the chemocline during fall (autumn) and resulted in 3–8 g m‐2 day‐1 of organic matter being deposited as a dark layer in sediment traps which were suspended in the permanently anaerobic zone. This mass mortality of photosynthetic bacteria occurred in late autumn following the annual thermal destratification of the lake's mixolimnion. Wind mixing during this period of homeothermy resulted in the introduction of low levels of dissolved oxygen into the lake's chemocline. The ensuing mass mortality of photosynthetic bacteria resulted in the release of elemental sulphur as the sulphur‐rich bacteria decomposed and sank to the bottom of the lake. The ferrous ions in the water below a depth of 15 m in Crawford Lake reacted with this sulphur to form black ferrous sulphides and pyrite which formed a dark microlamina on the lake floor. Each dark microlamina was overlain by a light coloured (calcite‐rich) layer which was deposited each spring and summer during the 3 yr period of this study.The mechanism of microlamina formation elucidated here has been based on the examination of bi‐weekly sediment trap information. This approach has permitted an explanation of the mechanisms by which specific events such as calcite precipitation and phytoplankton seasonal succession are transcribed into the sediment record.
Gravel‐topped offshore bar sequences in the Lower Carboniferous of southern Ireland
Authors: COTTER EDWARD 
Published: June 2006

ABSTRACTWithin the Kinsale Formation (Lower Carboniferous) of southern Ireland are pebbly sandstones and conglomerates contained in what is known locally as the Garryvoe conglomerate facies. In this facies there are three main groups of lithologies: (a) heterolithic mudrocks and sandstones characterized by a wide variety of wave‐produced structures; (b) sandstones dominated by swaley cross‐stratification (SCS), parallel lamination, and rare hummocky cross‐stratification (HCS); and (c) pebbly sandstones and conglomerates occurring as discrete beds or as gravel clasts dispersed through SCS sets. Successions of the facies comprise units of heterolithic mudrock and rippled sandstone alternating repeatedly with coarsening‐upward units of SCS pebbly sandstone capped by top‐surface granule and pebble lags.The Garryvoe conglomerate facies accumulated in a system of offshore bars on a muddy shallow‐marine shelf that was dominated by waves and currents generated by storms. Sands and gravels were bypassed from a contemporaneous northerly coastal zone to the shelf, where they were moulded by the storm‐generated flow into low, broad, sand ridges (offshore bars). The elongate bars were spaced kilometres apart, oriented obliquely to the coast, and separated by muddy interbar troughs. Their surfaces were largely covered by hummocky and swaley forms. Long‐term, gradual seaward migration of the offshore bars concentrated gravels on landward flanks from the dispersed pebbly sands that were on the crests and seaward flanks. Exceptionally intense storms could form laterally extensive winnowed gravel lags above thinned bar sequences. Such storms could also flush gravel‐bearing turbidity currents into muddy interbar trough areas.
Boulder beds in the glaciogenic Permo‐Carboniferous Dwyka Formation in South Africa
Authors: VISSER J. N. J. , HALL K. J. 
Published: June 2006

ABSTRACTSingle‐layer and massive boulder beds, which include boulder pavements, are sporadically distributed in the glaciogenic Permo‐Carboniferous Dwyka Formation. These matrix‐supported beds consist of moderately to poorly sorted, rounded boulders, cobbles and pebbles with a clast composition similar to those in the underlying or overlying diamictite. Alternatively, the clasts are composed of monolithic basement rock‐types. The clasts show a long‐axis orientation which, in the case of the boulder pavements, is parallel to the striae on the pavements.The various types of boulder beds have a similar mode of deposition and their subglacial origin is evidenced by the clast orientation, clasts with stoss and lee sides, stacking of clasts, and the development of a cleavage in the matrix due to horizontal stresses exerted by the boulders in the subglacial sediment. Subglacial streams, kame mounds, subaqeously winnowed till, or boulder beaches supplied the coarse debris which was entrained in the basal ice by plastic flow and regelation. Selective lodgement of the transported boulders occurred down‐glacier when the basal thermal conditions changed from cold‐freezing to warm‐melting. The formation of the different types of boulder beds is thought to depend primarily on the concentration of coarse debris in the basal ice.
Contained (reflected) turbidity currents from the Middle Ordovician Cloridorme Formation, Quebec, Canada: an alternative to the antidune hypothesis
Authors: PICKERING KEVIN T. , HISCOTT RICHARD N. 
Published: June 2006

ABSTRACTThe parautochthonous Cloridorme Formation is a syn‐orogenic flysch succession that was deposited in an elongate foredeep basin as mainly lower middle‐fan, outer‐fan, and basin‐floor deposits. The basin‐floor deposits (about 1.5 km thick) are confined to members β1, β2 and γ1, and are characterized by graded, thick (1–10 m) mud‐rich calcareous greywacke beds previously interpreted as deposits of concentrated, muddy, unidirectional turbidity currents that locally generated backset (antidune) lamination in internally stratified flows.The dominant flow directions were from east to west, but west to east transport also occurred, as seen in the orientation of ripples, climbing ripples, flutes, consistently overturned flames, and grain imbrication. We believe that the flows that deposited these thick calcareous greywacke beds reversed by roughly 180° one or more times during deposition of the lower sandy part of the beds. Flow reversals are consistent with the sharp grain‐size breaks and mud partings within sandy divisions. Measurement of grain fabric relative to stratification in the most celebrated ‘antidune’ bedforms indicates flow from west to east; thus, the bedforms were produced by west‐to‐east migration of megaripples, not by the upcurrent migration of antidunes.The thick muddy beds were deposited by large‐volume, muddy flows that were deflected and reflected from the side slopes and internal topographic highs of a confined basin floor, much like the ‘Contessa’ and similar beds of the Italian Apennines. Large quantities of suspended mud were ponded above the irregular basin floor and settled to produce the thick silty mudstone caps seen on each bed. Because of their mode of emplacement, we propose that these beds be called contained turbidites.
Sedimentation and palaeoenvironments of Late Cretaceous crater‐lake deposits in Bushmanland, South Africa
Authors: SMITH R. M. H. 
Published: June 2006

ABSTRACTA large diameter borehole core from an epiclastic kimberlite remnant on the farm Stompoor in the Prieska district, Cape Province, contains a continuous 76 m section of fossiliferous sediments interpreted as having accumulated within a crater‐lake during the Late Cretaceous. Three distinct facies associations reflect depositional processes that prevailed in offshore areas of the original lake. Facies Association A: matrix‐supported pebble conglomerates comprising a chaotic assemblage of pyroclastic, basement and country rocks set in a fine‐grained matrix. Flat, non‐erosional basal surfaces with ‘frozen’ rip‐up clasts, the protrusion of matrix‐supported clasts above the upper surfaces and a direct relationship between maximum clast size and bed thickness suggest deposition from debris flows that originated subaerially on pyroclastic talus cones surrounding the crater. Facies Association B: alternating thin beds of matrix‐supported granule conglomerate, structureless fine‐grained sandstone and parallel laminated mudrock. Small fining‐upward sequences within these beds are comparable to turbidite Bouma Tade, Tde. Numerous partings display petrified fish and frog skeletons, as well as bivalve, gastropod and ostracode shells, leaf impressions, insect wings and a possible bird bone. These beds were deposited by thin debris‐flows and turbidity underflows interspersed with periods of ‘pelagic’ sedimentation. Facies Association C: microlaminated mudstone beds containing scattered ‘dropstone lapilli’. The lamination is imparted by alternating Ca‐rich/Ca‐poor layers which may reflect climatic seasonality. They are interpreted as the result of seasonally influenced suspension settling through a thermally stratified water column.Short‐term periodicities in conglomerate bed thicknesses are interpreted as the result of successive block caving of a slump scar giving rise to several debris flows from the same source area. Seismic shock from nearby volcanism may have simultaneously triggered slumps on both subaerial and subaqueous slopes. Dropstone lapilli in Type C beds and the preponderance of load casting in Type B beds support this interpretation. An estimate of the time span involved in accumulating 76 m of crater lake sediments based on the possible seasonal imprint of Type C beds gives a figure of some 220,000 yr.