bluuebunny/crossref_metadata_2025_split huggingface dataset:
PROBABLE CHANGES IN THE COMPOSITION OF SEA WATER DURING THE COURSE OF GEOLOGICAL TIME1
Authors: RONOV A. B. 
Published: June 2006

SUMMARYThe initial geological facts are considered on which the author bases on of the possible variants of the evolutionary scheme of the stratisphere, ocean and atmosphere composition from the Early Precambrian to the Recent. Some general tendencies and causal relationships in the development of these external shells of the earth are traced.The object of this paper is to trace the evolution of the compositions of the sedimentary shell, the world ocean and the atmosphere from the Early Precambrian to the Recent period. Further, an attempt is made to elucidate some general tendencies in the development of these outer shells of the earth, in the changes of magmatic rock composition and in the history of tectonic movements and to establish causal relationships between them. The solution suggested is one of the possible variants, as the data used and the assumptions that have been made are not uniformly reliable for the different stages of geological history.
ON ENVIRONMENT‐SENSITIVE GRAIN‐SIZE PARAMETERS
Authors: KOLDIJK W. S. 
Published: June 2006

SUMMARYMoment measures are to be preferred over graphic measures for a reliable description of the depositional environment of sands. This is demonstrated by coarse beach and river sands from the Ria de Arosa (northwestern Spain). A PL/1 computerprogram for the calculation of graphic and moment measures has been added to stimulate other comparative studies.
PRELIMINARY EXPERIMENTS ON HYDRODYNAMIC MOVEMENT INDUCED BY EVAPORATION AND THEIR BEARING ON THE DOLOMITE PROBLEM
Authors: HSÜ K. JINGHWA , SIEGENTHALER CHRISTOPH 
Published: June 2006

SUMMARYExperiments were performed to demonstrate that saline interstitial waters under an arid coastal plain could be set in hydrodynamic movement to replace the evaporative loss near the surface.In contrast to movement in a vadose zone, which is related to capillary forces caused by surface tension, the type of movement we observed was induced by a vertical hydraulic gradient under the evaporated area. Fluid flow through porous media was induced by an upward decrease in hydrodynamic potential during evaporation. We propose to call this type of movement evaporative pumping.Experiments further verified that flow rate induced by evaporative pumping was directly governed by evaporation alone; linear flow rate through coarse sand and that through very fine silt was approximately the same under the same evaporative condition. Yet the movement apparently obeyed Darcy's law. Since the permeability of the medium was fixed, and the flow rate was dictated by evaporation, only the hydraulic gradient could be the dependent variable in the Darcy equation. We observed that the gradient was indeed much greater in relative impermeable silt than in permeable sand, when the water to replace evaporative loss must flow with the same rate through those media.Our experiments suggested that hydrodynamic movement induced by evaporation could be an effective mechanism to transport magnesium‐bearing solutions through relatively impermeable sediments of an arid coastal plain. Computations showed that dolomitization by evaporative pumping could proceed at a rate to account for the origin of Recent dolomite crusts, and for the great thickness of ancient supratidal dolomites. In contrast, we believed that dolomitization by seepage reflux or by groundwaters cannot be extensive, because of the inadequate magnesium‐supply rates by such waters.
THE CHEMISTRY OF SUBMARINE CEMENT FORMATION AT DOHAT HUSSAIN IN THE PERSIAN GULF
Authors: DE GROOT K. 
Published: June 2006

SUMMARYA chemical study made at Dohat Hussain lagoon in Qatar, has supported other field observations that submarine carbonate cementation is probably active there today. The source of the cement is the lagoon water, supersaturated with aragonite. In the lagoon the supersaturation is too low to effect spontaneous nucleation and thus precipitation of carbonate, but just below the sediment‐water interface both the presence of a stable substrate and supersaturation promote aragonite precipitation. In soft sediment layers in between cemented layers no supersaturation was found. The carbonate saturation of various water samples is tabulated below:
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STRATIGRAPHY AND GEOLOGIC HISTORY OF THE SABKHA, ABU DHABI, PERSIAN GULF
Authors: EVANS G. , SCHMIDT V. , BUSH P. , NELSON H. 
Published: June 2006

SUMMARYThe sabkha of Abu Dhabi was formed during the past 7,000 years by wind erosion of pre‐existing dunes and progradation of subaqueous, intertidal, and supratidal carbonate sediments. Marine transgression began in this area about 7,000 years ago and reached an apparent high about 1 m above its present level somewhat prior to 4,000 years B.P. Since then progradation of intertidal and supratidal sediments has taken place; this began 3,750 years ago. Arid conditions over the sabkha have produced large amounts of gypsum and anhydrite and lesser amounts of dolomite, magnesite, celestite and halite.
GRAIN‐SIZE IMAGE OF CLASTIC DEPOSITS
Authors: PASSEGA R. , BYRAMJEE R. 
Published: June 2006

SUMMARYA clastic deposit is represented by several diagrams. C‐M diagrams in which C is the one‐percentile, M the median of the grain‐size distribution, characterize the coarsest fractions of the samples. F‐M, L‐M and A‐M diagrams in which F, L and A, respectively, are the percentages by weight in the samples of grains finer than 125, 31 and 4 μ characterize the finest fractions. As a group, these diagrams form the “grain‐size image” of a deposit.The above parameters were selected because they are closely related to transport and deposition mechanisms. As a consequence, the grain‐size image gives fairly precise information on hydraulic conditions under which a deposit is formed.A large number of deposits were compared by means of their grain‐size images. This comparison shows that some texture characteristics are related to the environment of deposition while others are controlled by basin mobility. Mobility should, therefore, be considered when comparing sediments of different basins and particularly recent and ancient sediments.Relationships which exist between certain sizes of clastic grains and the most probable deposition mechanism are used to classify clastic sediments by subdividing them into types indicative of their genesis.Grain‐size types can be represented on maps and cross‐sections. Grain‐size facies maps of ancient formations represent lateral variations of texture and of hydraulic conditions across all basin environments and do not necessitate a reconstruction of these environments, which, often, is questionable. These maps, sell suited to show and project sedimentary trends, complete conventional isopach and sand/shale ratio maps. Integrated with ecological determinations and sedimentary structure descriptions, grain‐size facies maps are a means of environment analysis.
GRAIN SIZE OF TURBIDITE RIPPLES
Authors: KUENEN PH. H. , HUMBERT F. L. 
Published: June 2006

SUMMARYMany, but not all, current ripples show log‐normal grain‐size distribution and good sorting (P. D. Trask). A range in medians was measured from fifty to several hundred microns. Turbidite ripples are log‐normal, very well‐sorted and are restricted to medians of very fine sand to silt (< 130 μ) because the particles have been supplied in suspension at rippling velocity. Experimental suspension current ripples formed at about 50–60 cm/sec are similar in composition and structure to turbidite ripples. The continuous supply results in climbing ripples. The restricted grain size and the internal structure of turbidite ripples both form strong evidence against the action of normal currents. The number of grain‐size analyses is still rather small.
A PYRITIZED LIMESTONE HARDGROUND IN THE LOWER JURASSIC OF DORSET (ENGLAND)
Authors: HALLAM A. 
Published: June 2006

SUMMARYDetailed documentation and interpretation is given of a thin band of limestone nodules in the Lower Lias of Dorset, which has been subjected to early lithification, exhumation on the sea bed and incrustation and boring by organisms in a more turbulent and shallow‐water regime than that of deposition. Final burial has been followed by extensive pyritization. The stratigraphical gap during which these events took place is less than two ammonite zones.
STRUCTURAL AND TEXTURAL EVIDENCE OF EARLY LITHIFICATION IN FINE‐GRAINED CARBONATE ROCKS
Authors: ZANKL H. 
Published: June 2006

SUMMARYAbsence of compaction, intraformational breccias, resedimention, internal sediments and synsedimentary hardgrounds indicate early lithification of finegrained carbonate rocks. One of the factors controlling early lithification is the purity of lime mud. Less than 2% of insoluble residue (especially clay minerals) favours cementation and recrystallisation before further sediment accumulation causes compaction. Thus, early lithification is terminated in or near the environment of sedimentation. “Electrodiagenesis” is considered to be a possible mechanism for cementation.
THE DISTRIBUTION OF CLAY MINERALS IN THE OCEANS
Authors: RATEEV M. A. , GORBUNOVA Z. N. , LISITZYN A. P. , NOSOV G. L. 
Published: June 2006

SUMMARYIn order to obtain data comparable to those of Biscaye (1965) on the Atlantic Ocean, the authors carried out quantitative X‐ray determinations of clay minerals in the sediments of the Indian and Pacific oceans using the Biscayemethod.
MINERALOGY AND CHEMISTRY OF TONSTEINS FROM CARBONIFEROUS SEQUENCES IN GREAT BRITAIN
Authors: PRICE N. B. , DUFF P. McL. D. 
Published: June 2006

SUMMARYTonsteins from Westphalian Coal Measures in England are compared mineralogically and chemically with tonsteins of volcanic origin from coalbearing sequences of Namurian and Westphalian age in Scotland. Differences are apparent between tonsteins occurring as partings within coals (“coal tonsteins”) and those interbedded with inter‐seam sedimentary rocks (“non‐coal tonsteins”). The coal tonsteins show higher titanium values and in some cases contain minerals of the goyazite series. Sedimentological, mineralogical and chemical evidence is reviewed and the conclusion reached that all tonsteins examined could have originated as thin layers of volcanic ash. Subsequent alteration depended upon the environment of deposition into which the ash fell.
THE OBLIQUE ASDIC AND ITS USE IN AN INVESTIGATION OF A MARINE HIGH‐ENERGY ENVIRONMENT1
Authors: DOBSON MAX 
Published: June 2006

SUMMARYMethods whereby an Asdic may be used empirically to examine the sea bed are discussed. They indicate that on flat sea bottoms the effects of impedance and attenuation combine to produce a record usually distinctive enough to broadly classify the sediment over which the vessel is passing. These methods were used to interpret an area of unconsolidated sand, gravel and mud in the region of Arklow off the east Irish Coast. Echo‐sounder traverses and sea bed sampling were also employed to assist with the interpretations. The sea bed is composed of dissected residual gravels covered in places with mobile sand displaying a great variety of high‐energy bed forms. Mechanisms of sub‐littoral sediment circulation, based largely on the bed forms recognized in the Asdic records, are also discussed.
A BURET CYLINDER FOR GRAIN‐SIZE ANALYSIS OF SILT AND CLAY (WITH ALGOL‐PROGRAM)
Authors: FABRICIUS F. , MÜLLER ST. 
Published: June 2006

SUMMARYA new apparatus, the “buret cylinder”, was constructed in order to increase the efficiency of the size analysis of fine‐grained sediments. Its uncomplicated operation and automatic levelling enables working in series of ten samples or more at a time. This method, an improvement of the “pipet method”, works with an accuracy comparable to that of the “Atterberg method”.An ALGOL‐program was compiled to compute all data, obtained from the granulometric analysis of the entire sediment. In the output, the numerical parameters are printed out and a simple frequency and a cumulative diagram is plotted. The computer program works for grain sizes from −6 phi (64 mm φ) to +9 phi (2 u φ). Two procedures can be applied alternatively: (a) sieving—buret analysis; and (b) sieving—visual accumulation tube—buret analysis.
FACIES OF AN EARLY MIOCENE VOLCANIC ARC, MALEKULA ISLAND, NEW HEBRIDES
Authors: MITCHELL A. H. G. 
Published: June 2006

SUMMARYOn Malekula Island pre‐Miocene pelagic red mudstones are in tectonic contact with a thick marine succession of Early Miocene age, which is intruded by basaltic and andesitic dykes and sills with a calc‐alkaline composition and by plutons. This succession is in faulted contact with Middle Miocene sedimentary rocks.The Lower Miocene succession consists of quartz‐free volcanoclastic rocks, detrital limestones and pelagic sediments, and rare lava flows. Fifteen sedimentary facies have been recognized, all of which accumulated below the zone of strong wave or current action. Vertical changes in facies are common; facies relationships and associations and internal sedimentary structures indicate that many facies were transported by mass gravity processes. Texture and composition of clasts in the volcanoclastic rocks show that some facies were derived from subaerially erupted volcanic rocks, and others from submarine volcanoes. Clastic limestones consist largely of algal and coral fragments and benthonic foraminifers.The Lower Miocene palaeogeography resembled that in and around volcanic chains in present island arcs. Subaerial and submarine volcanoes fed by minor intrusions supplied epiclastic, pyroclastic and autoclastic debris which accumulated in deep water around the volcanic chain. Carbonate detritus was derived from reefs bordering the volcanic islands.The Middle Miocene succession consists of volcanic and reef‐derived turbid‐ites, pelagic sediments and tuffs. The epiclastic rocks in this succession were derived from the uplifted rocks of Early Miocene age and from bordering reefs.The presence of some ancient volcanic arcs, now located either within existing ares or within geosynclinal successions lying in or on the borders of continents, may be indicated only by quartz‐poor turbidites containing abundant calc‐alkaline volcanic detritus.
DOWNCURRENT TEXTURAL CHANGES IN ORDOVICIAN TURBIDITE GREYWACKES
Authors: PARKASH BARHAM , MIDDLETON GERARD V. 
Published: June 2006

SUMMARYLongitudinal and vertical variation in grain orientation and size has been studied in eight turbidite greywacke beds from the Cloridorme Formation (Middle Ordovician), Gaspé, Quebec, Canada. The beds are exposed on a wave‐cut platform near Grande Vallée, Gaspé. These beds were traced for about two miles along the strike (276°), which is almost parallel to the average current direction (274°) as indicated by sole marks.Agreement between grain orientation and other internal current‐direction indicators such as graptolites and intra‐bed lineation shows that grain fabric is primary in nature and that grains are typically aligned parallel to the current direction. Grain orientations are generally statistically non‐significant in the upper massive part of the beds in the proximal region and significant in the rest of the beds. Most of the significant grain orientations are close to the sole direction in the proximal region and deviate from the sole direction by as much as 90° in the distal region. Grain orientations are increasingly divergent from the base towards the top of the bed. Current‐normal grain orientations are observed in a plane‐laminated part of a bed.The beds show a good grading in the proximal area and are ungraded or slightly reverse graded in the distal area. These grading characteristics are exhibited by both the mean and maximum grain size. Most beds show no appreciable variation in the mean grain size at the base of the bed along the strike. However, for one bed, the largest mean size at the base occurs in the middle of the outcrop and grain size decreases from this point both in the upstream and downstream directions.
COMPARISON OF POST‐SEDIMENTARY ALTERATIONS OF OIL‐, GAS‐ AND WATER‐BEARING ROCKS
Authors: YURKOVA R. M. 
Published: June 2006

SUMMARYOne of the productive horizons (17th) of north Sakhalin has been studied. The areas within and beyond oil and gas pools, near the top and at the flanks of structures were compared with areas where the horizon under study was waterbearing. The rocks were least transformed by secondary processes within oil accumulations, where a sudden increase was observed in the content of feldspars and accessory minerals (epidote, ilmenite and sphene) which had not undergone intrastratal solution. Inside gas pools, however, no deceleration of epigenesis has been observed. This points to a more recent (post‐Pliocene) accumulation of gas, whereas the first oil migration in these Miocene strata occurred in the Upper Pliocene, according to the hampered epigenesis.
THE VARIABILITY OF MICACEOUS MINERALS IN SEDIMENTARY ROCKS
Authors: KOSSOVSKAYA A. G. , DRITS V. A. 
Published: June 2006

SUMMARYRelationships between crystal chemistry and genetic conditions are presented for a series of dioctahedral micaceous minerals. Using a ferruginicity index, three groups of micaceous minerals are distinguished: Al‐micas, Fe‐illites, and glauconites. The degree of Al‐for‐Si substitution in the tetrahedral sheets of micaceous minerals depends on their thermodynamic genetic conditions. If pressure and temperature increase, the Al‐IV content increases and the octahedral sheet is “cleaned” from divalent cations. This process is accompanied by structural alteration with a polytype sequence 1Md‐1M‐2M1. Tetrahedral and octahedral charges are the same for micaceous minerals formed at the surface (sedimentogenesis/diagenesis) and are independent of the iron content. For most illites of sedimentary rocks an authigenic origin is suggested.
EXPERIMENTAL STUDY OF THE SORPTION OF POTASSIUM BY MONTMORILLONITE
Authors: MURAVYOV V. I. , SAKHAROV B. A. 
Published: June 2006

SUMMARYExperimental studies on saturation of montmorillonite with potassium showed that sorption of potassium tends to produce a regular alternation of the interlayer regions.The sorptive nature of the potassium fixation by montmorillonite appears to form the basis of the epigenetic formation of rectorite.
LONGITUDINAL DUNES OF THE NORTHWESTERN EDGE OF THE SIMPSON DESERT, NORTHERN TERRITORY, AUSTRALIA, 1. GEOMORPHOLOGY AND GRAIN SIZE RELATIONSHIPS
Authors: FOLK ROBERT L. 
Published: June 2006

ABSTRACTOrigin of the longitudinal dune form is reviewed. The spectacular longitudinal dunes of the Simpson desert are caused by helicoidal wind flow of the prevailing south‐southeastern winds, acting upon ancient alluvial plains. Critical in this theory is the evidence from tuning‐fork junctures, which open upwind as do similar features in other geologic realms of primarily one‐directional currents undergoing second‐order helicoidal circulation.A summary of previous work on using grain size to distinguish beach from dune sands reveals the consistent good sorting and positive skewness of coastal dunes. Simpson desert dunes are also positively‐skewed, but are not as well sorted as coastal dunes because they are only recently derived from poorly‐sorted alluvial source sediments. Dune crests are coarsest and best sorted because they are made out of the most easily saltated fine sand (about 2.5 ø); windward flanks, leeward flanks, and reg are progressively finer and also show regular and explainable changes in the higher‐order grain‐size parameters. Both dune and reg sediments are made of polymodal mixtures, giving rise to a “quantum theory” of aeolian deposition.
SLUMPING ON A CONTINENTAL SLOPE INCLINED AT 1°–4°
Authors: LEWIS K. B. 
Published: June 2006

ABSTRACTContinuous seismic profiles from the upper continental slope east of North Islands, New Zealand, show that surface sediment 10–50 m thick has slumped down bedding planes sloping at 1°–4°.There are four slumps, the Kidnappers Slump which has an area of 250 km2, the Paoanui Slump of 80 km2, a small slump of only several square kilometers and a slump of undetermined extent. All occurred during the last 20,000 years in Last Glacial Age sediments. A glide plane is exposed at the head of each slump and beds are thrust or contorted at the toe of some slumps.Slumping was probably caused by the failure of loosely packed sandy silt during major earthquakes.
CORRELATION OF SEDIMENT CORES ON THE BASIS OF THEIR MAGNETIZATION
Authors: HEYE DIETRICH 
Published: June 2006

ABSTRACTSediment cores originating from the Indian and the Atlantic Ocean were investigated. The declination of the cores was measured non‐destructively. In both regions it was possible to correlate several cores on the basis of their magnetization (intensity correlation in contrast to correlation of paleomagnetic reversals). Additional layers of turbidity‐currents and a layer of volcanic material were detected.
EFFECT OF CLAY ON THE ACCURACY OF THE HYDROMETER METHOD
Authors: MADHAV M. R. , SUBRAMANYA K. 
Published: June 2006

ABSTRACTEven small colloidal clay fractions in suspension affect markedly the results from a hydrometer test. The discrepancies are due to non‐consideration of specific gravity and relative viscosity of the actual clay‐water suspension. Therefore, actual—i.e., experimentally or otherwise determined—values of specific gravity and relative viscosity should be used instead of the conventionally used values for the specific gravity and the coefficient of viscosity. Expressed in terms of this study, in equations 1 and 2 the values of G1 and n should be replaced by G11 and nr, respectively. Another simple but time‐consuming remedy is to remove the clay content from the soil by repeated decantation before conducting the hydrometer analysis.
TEXTURAL DIFFERENTIATION ON THE SHORE FACE DURING EROSIONAL RETREAT OF AN UNCONSOLIDATED COAST, CAPE HENRY TO CAPE HATTERAS, WESTERN NORTH ATLANTIC SHELF
Authors: SWIFT DONALD J. P. , SANFORD ROBERT B. , JR CHARLES E. DILL , AVIGNONE NICHOLAS F. 
Published: June 2006

ABSTRACTIn order to evaluate a model of Holocene shelf sediment distribution requiring a nearshore modern sand facies and an offshore relict sand facies, we have undertaken a textural reconnaissance of the Virginia‐North Carolina Coast between Capes Henry and Hatteras. Grab samples were subjected to grain‐size analysis by means of a modified Woods Hole Rapid Sediment Analyser. Textural provinces were erected with the aid of factor vector analysis. These include medium‐grained sands of the beach and surf zones; seaward fining, fine‐grained sands of the shore face, and heterogenous sands of the sea floor. In this latter province, grain size is controlled by a ridge and swale topography, with coarser sand on the crests. Coast‐wise grain‐size trends on the beach and shore face can be explained by assuming that wave heights increase toward the south, and that the Pleistocene sediment source is exposed higher on the shore face in the north than it is in the south. The shore face is retrograding, except in the vicinity of Diamond Shoals. There is textural evidence for a former Albemarle River channel, which bisects the study area. A model for sediment fractionation on a retreating barrier coast with low sediment input is proposed, based on studies which indicate that on such coasts: (1) barrier superstructures retreat more or less continuously by upper shore‐face erosion and storm washover; and (2) lower shore‐face erosion results in an equal‐volume aggradation of the adjacent sea floor, and forms the leading edge of the Holocene transgressive sand sheet. The nearshore “modern” sands and offshore “relict” sands are both present in the study area, but the terms are unnecessarily restrictive. Both are “relict” in the sense of being derived from a Pleistocene substrate, and both are “modern” in the sense of having undergone adjustment to a modern hydraulic regime. While modern and relict are useful general terms, it is convenient in this area to refer to a Holocene barrier sand prism, versus a Holocene transgressive sand sheet.