scholarly journals VI.—On the Original form of Sedimentary Deposits

1903 ◽  
Vol 10 (2) ◽  
pp. 72-80
Author(s):  
Rev. J. F. Blake
Keyword(s):  
Fine Sediment ◽  
Original Form ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Coarse Sediment ◽  
London Clay

We may now examine how far these theoretical conclusions explain and are confirmed by what is seen in nature. First we know that in most formations there are great masses of what is now, or must have been once, fine-grained sediment. These often make up the bulk of the formation. We may quote the Ordovician, Silurian, and Devonian slates, the Keuper, Lias, Oxford and Kimmeridge Clays, the G-ault and London Clay; but we can give no such list of thick masses of marine sandstone. Fine sediment, therefore, has, as a matter of fact, made thicker masses of rock than coarse sediment; but this could not be the case if deposits thinned out seawards, where the fine sediment is carried. Again, it is impossible to imagine a thickness of a thousand feet and more constantly occupying a position near the shore; there is no room for it. If you depress the land, you remove the shore.

III.—On the Original Form of Sedimentary Deposits

1903 ◽  
Vol 10 (1) ◽  
pp. 12-18 ◽  
Author(s):  
J. F. Blake
Keyword(s):  
Essential Elements ◽  
Original Form ◽  
Sedimentary Deposits ◽  
Sea Bottom ◽  
Theoretical Considerations ◽  
Theoretical Results

The form of the deposits that are taking place on the sea-bottom at the present day is one of the essential elements required to be known when we wish to interpret the submarine contours, as throwing light on the submergence or elevation of the land in late geological times, or when we propose to use the variation of thickness of the strata deposited during any epoch as an indication of the position of the shore-lines at that time.In the case of deposits in small or temporary masses of water, their form and arrangement may sometimes be observed directly; but in the case of the deposits in the sea, where we can neither remove the water nor make borings beneath it, we can only avail ourselves of theoretical considerations.It might have been expected that the original form of various sedimentary deposits would have been considered in detail long ago, but as a matter of fact the few writers who have touched upon the question have mostly been content with the assumption that deposits taken as a whole are thickest near the source of supply, and the figures given in illustration of the arrangement of various kinds, and thereby the shape of each, are remarkable for their variety.As the theoretical results at which I have arrived differ fundamentally from the ordinary assumptions, it is to be hoped that some one will be able to point out the fallacy, if any, which has led me astray, and to explain more satisfactorily the observed features which appear to confirm the theory.

scholarly journals Synrift sandstones and clayey rocks: bulk chemical composition and location on a number of discriminant paleogeodynamic diagrams

2019 ◽  
pp. 439-465
Author(s):  
A. V. Maslov ◽  
V. N. Podkovyrov ◽  
E. Z. Gareev ◽  
A. D. Nozhkin
Keyword(s):  
Chemical Composition ◽  
Continental Margins ◽  
Bulk Chemical Composition ◽  
East European ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Data Points ◽  
Bulk Chemical ◽  
Clayey Rocks ◽  
Active Continental Margins

The bulk chemical composition of synrift sandstones and associated clayey rocks has been analized, and the distribution of the fields they form has been studied on discriminant paleogeodynamic SiO2K2O/Na2O [Roser, Korsch, 1986] and DF1DF2 [Verma, Armstrong-Altrin, 2013] diagrams. The studied sandstones in terms of bulk chemical composition mainly correspond to greywacke, lititic, arkose and subarkose psammites; Sublitites and quartz arenites are also found. A significant part in the analyzed data massif consists of psammites, in which log(Na2O/K2O)-1.0; missing on the Pettijohn classification chart. This confirms our conclusion, based on the results of mineralogical and petrographic studies, that the sedimentary infill of rift structures unites immature sandstones, the detrital framework of which was formed due to erosion of local sources, represented by various magmatic and sedimentary formations. Synrift clayey rocks, compared with sandstones, are composed of more mature fine-grained siliciclastics. As follows from the distribution of figurative data points of clayey rocks on the F1F2 diagram [Roser, Korsch, 1988], its sources were mainly sedimentary deposits. The content of most of the main rock-forming oxides in the synrift sandstones is almost the same as in silt-sandstone rocks present in the Upper Precambrian-Phanerozoic sedimentary mega-complex of the East European Plate, but at the same time differs significantly from the Proterozoic and Phanerozoic cratonic sediments, as well as from the average composition upper continental crust. It is shown that the distribution of the fields of syntift sandstones and clayey rocks on the SiO2K2O/Na2O diagram does not have any distinct features, and their figurative data points are localized in the areas of terrigenous rocks of passive and active continental margins. On the DF1DF2 diagram, the fields of the studied psammites and clayey rocks are located in areas of riftogenous and collisional environments. We have proposed a different position of the border between these areas in the diagram, which will require further verification.

Electrical resistivity tomography investigations in the ufita Valley (southern Italy).

2008 ◽  
Vol 51 (1) ◽  
Author(s):  
A. Giocoli ◽  
C. Magrì ◽  
P. Vannoli ◽  
S. Piscitelli ◽  
E. Rizzo ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistivity Tomography ◽  
Southern Italy ◽  
Normal Fault ◽  
Fluvial Sediments ◽  
Resistivity Tomography ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Lacustrine Deposits ◽  
Sedimentary Deposit

Several Electrical Resistivity Tomography (ERT) surveys have been carried out to study the subsurface structural and sedimentary settings of the upper Ufita River valley, and to evaluate their efficiency to distinguish the geological boundary between shallow Quaternary sedimentary deposits and clayey bedrock characterized by moderate resistivity contrast. Five shallow ERTs were carried out across a morphological scarp running at the foot of the northeastern slope of the valley. This valley shoulder is characterized by a set of triangular facets, that some authors associated to the presence of a SW-dipping normal fault. The geological studies allow us to interpret the shallow ERTs results obtaining a resistivity range for each Quaternary sedimentary deposit. The tomographies showed the geometrical relationships of alluvial and slope deposits, having a maximum thickness of 30-40 m, and the morphology of the bedrock. The resistivity range obtained for each sedimentary body has been used for calibrating the tomographic results of one 3560m-long deep ERT carried out across the deeper part of the intramountain depression with an investigation depth of about 170 m. The deep resistivity result highlighted the complex alluvial setting, characterized by alternating fine grained lacustrine deposits and coarser gravelly fluvial sediments.

Study of deposition of fine sediment within the pores of a coarse sediment bed stream

2013 ◽  
Vol 28 (2) ◽  
pp. 210-219 ◽  
Author(s):  
N.K. KHULLAR ◽  
U.C. KOTHYARI ◽  
K.G. Ranga RAJU
Keyword(s):  
Fine Sediment ◽  
Coarse Sediment ◽  
Sediment Bed

scholarly journals Identification of deep subaqueous co-seismic scarps through specific coeval sedimentation in Lesser Antilles: implication for seismic hazard

2012 ◽  
Vol 12 (5) ◽  
pp. 1755-1767 ◽  
Author(s):  
C. Beck ◽  
J.-L. Reyss ◽  
F. Leclerc ◽  
E. Moreno ◽  
N. Feuillet ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Silty Sand ◽  
Lesser Antilles ◽  
Normal Faults ◽  
Fine Grained ◽  
210Pb And 137Cs ◽  
Sedimentary Deposits ◽  
Unsupported 210Pb ◽  
Continuous Displacement ◽  
Redox Level

Abstract. During the GWADASEIS cruise (Lesser Antilles volcanic arc, February–March 2009) a very high resolution (VHR) seismic-reflection survey was performed in order to constrain Late Quaternary to Present faulting. The profiles we obtained evidence frequent "ponding" of reworked sediments in the deepest areas, similar to the deposition of Mediterranean "homogenites". These bodies are acoustically transparent (few ms t.w.t. thick) and are often deposited on the hanging walls of dominantly normal faults, at the base of scarps. Their thickness appears sufficient to compensate (i.e. bury) co-seismic scarps between successive earthquakes, resulting in a flat and horizontal sea floor through time. In a selected area (offshore Montserrat and Nevis islands), piston coring (4 to 7 m long) was dedicated to a sedimentological analysis of the most recent of these particular layers. It corresponds to non-stratified homogenous calcareous silty sand (reworked calcareous plankton and minor volcanoclastics). This layer can be up to 2 m thick, and overlies fine-grained hemipelagites. The upper centimeters of the latter represent the normal RedOx water/sediment interface. 210Pb and 137Cs activities lack in the massive sands, while a normal profile of unsupported 210Pb decrease is observed in the hemipelagite below, together with a 137Cs peak corresponding to the Atmospheric Nuclear Experiments (1962). The RedOx level was thus capped by a recent instantaneous major sedimentary event considered as post-1970 AD; candidate seismic events to explain this sedimentary deposits are either the 16 March 1985 earthquake or the 8 October 1974 one (Mw = 6.3 and Mw = 7.4, respectively). This leads to consider that the syntectonic sedimentation in this area is not continuous but results from accumulation of thick homogenites deposited after the earthquakes (as observed in the following weeks after Haiti January 2010 event, McHugh et al., 2011). The existence of such deposits suggests that, in the area of study, vertical throw likely results from cumulated effects of separated earthquakes rather than from aseismic creep. Examination of VHR profiles shows that all major co-seismic offsets are recorded in the fault growth sequence and that co-seismic offsets can be precisely estimated. By using a sedimentation rate deduced from 210Pb decrease curve (0.5 mm yr−1) and taking into account minor reworking events detected in cores, we show that the Redonda system may have been responsible for five >M6 events during the last 34 000 yr. The approach presented in this work differs from fault activity analyses using displaced sets of isochronous surfaces and postulating co-seismic offsets. Combining VHR seismic imagery and coring we can decipher co-seismic vs. slow continuous displacement, and thus actually estimate the amplitude and the time distribution of major co-seismic offsets.

Lithostratigraphy of the Red and Norwich Crags of the Aldeburgh–Orford Area, south-east Suffolk

1985 ◽  
Vol 122 (3) ◽  
pp. 287-296 ◽  
Author(s):  
J. A. Zalasiewicz ◽  
S. J. Mathers
Keyword(s):  
Coarse Grained ◽  
Fine Grained ◽  
Clay Surface ◽  
London Clay

AbstractRecent investigations indicate that three distinct lithostratigraphical units can be recognized in the Red and Norwich Crag deposits of the area around Aldeburgh and Orford, Suffolk. These effectively represent a refinement of a stratigraphy originally suggested by Prestwich in 1871. A lowermost coarse-grained shelly sand, the Red Crag Formation, rests on an eroded London Clay surface and is banked against the Pliocene Coralline Crag. The Red Crag Formation passes upwards into a fine-grained generally unfossiliferous well-sorted sand, the Chillesford Sand Member, which overlaps the Red Crag Formation to rest directly on the Coralline Crag. The Chillesford Clay Member is regarded as the lateral equivalent of the upper Chillesford Sand Member, the two members together comprising the Norwich Crag Formation in this area. Sections that have been zoned palaeontologically may be integrated into this lithostratigraphical framework. These indicate that the Red Crag Formation correlates with the Pre-Ludhamian Stage, and the Chillesford Sand Member and the Chillesford Clay Member correlate with the Bramertonian Stage. Type sections are established for the three units described.

scholarly journals VI. — The Igneous Geology of the Bathgate and Linlithgow Hills. Part. II. Petrography

1906 ◽  
Vol 45 (1) ◽  
pp. 133-150 ◽  
Author(s):  
J. D. Falconer
Keyword(s):  
Chemical Composition ◽  
Water Vapour ◽  
The Other ◽  
Compact Structure ◽  
Open Structure ◽  
Secondary Minerals ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Other Hand ◽  
Coal Fields

The lavas of the Bathgate and Linlithgow Hills occur, as already described, in a series of zones alternating with sedimentary deposits. So far as their field characters are concerned they may be grouped with convenience into two classes: fine-grained, columnar, basaltic types, usually porphyritic with augite and olivine, rarely with felspar, and coarser-grained, doleritic types, usually much decomposed, not evidently porphyritic or porphyritic with olivine alone. The yellow crusts of the compact lavas are minutely vesicular and pumiceous, while steam-cavities are rare in the interior. The doleritic lavas on the other hand are coarsely vesicular and amygdaloidal above and below, and frequently also throughout. The blue basaltic types are relatively very fresh; the doleritic types are frequently entirely decomposed into a whitish, earthy material, with knots of limonite, calcite, and quartz, similar in many respects to the white trap of the coal-fields. Good examples of this mode of weathering may be found in the Riccarton Burn. The differences in texture are probably to be referred not so much to differences in chemical composition as to the effect of variation in the quantity of water vapour contained in the successive flows. The coarse and open structure of the dolerites has evidently also given freer scope to the action of decomposing influences than the more compact structure of the basalts. Both types are much veined by such secondary minerals as calcite, siderite, limonite, quartz, chalcedony, and various zeolites. Frequently cavities in the veins, steam-holes in the pumiceous crusts, and even vesicles within the solid rocks, are found filled with brown viscous pitch or black lustrous asphalt. Such occurrences undoubtedly indicate that these rocks have been subjected to some slight extent to post-volcanic pneumatolytic action.

scholarly journals A Holocene tephra layer within coastal aeolian deposits north of Caleta Olivia (Santa Cruz Province, Argentina)

2021 ◽  
Vol 48 (2) ◽  
pp. 267
Author(s):  
Giovanni Zanchetta ◽  
Marta Pappalardo ◽  
Alessio Di Roberto ◽  
Monica Bini ◽  
Ilenia Arienzo ◽  
...  
Keyword(s):  
Atlantic Coast ◽  
Sr Isotopes ◽  
Tephra Layer ◽  
Santa Cruz ◽  
Geochemical Composition ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Aeolian Deposits ◽  
Hudson Volcano ◽  
Ash Layer

In this paper we illustrate the stratigraphy, geochronology, and geochemistry (major, minor, trace elements and Sr-isotopes) of a Holocene tephra layer found within coastal sedimentary deposits north of Caleta Olivia (Santa Cruz Province, Argentina). The stratigraphic succession comprises beach deposits with basal erosive surface resting on the local substrate (“Formación Patagonia”) followed by a poorly developed paleosoil. The paleosoil is covered by a lenticular fine-grained (Mdφ: 5.2, 0.027 mm), well sorted (σφ: 1.2) volcanic ash layer and aeolian sands. The geochemical composition of shard fragments points to an origin from the Hudson volcano, located in the southern Andes, ca. 400 km to the west. The geochemistry, Sr-isotopes and the radiometric constraints (younger than the age of the underlying marine layer dated at ca. 4,100 a cal BP) further allow correlating this tephra with the so-called H2 eruption (ca. 3,900 a cal BP). This finding is of interest owing to the poor preservation potential of tephra within the Late Holocene sedimentary deposits of the Atlantic coast of Patagonia and represents the first finding of H2 eruption in this area, improving our knowledge of the dispersion of the fine-grained distal deposit of the Hudson volcanic explosive activity, thus allowing a better estimate of the eruptive dynamics and the risks associated with the Hudson volcano.

scholarly journals A Perspective on Stratigraphic, Vertically-Upward “Displacements or Dislocations” of Conodont-Elements: An Example From the Upper Devonian, Pre-Lithified, Black Shales of the Chattanooga Shale Formation In Tennessee, USA

2019 ◽  
Vol 8 (2) ◽  
pp. 35
Author(s):  
Michael Iannicelli
Keyword(s):  
Black Shale ◽  
Black Shales ◽  
Upper Devonian ◽  
Cold Climate ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Chattanooga Shale ◽  
Shale Formation ◽  
Freezing Temperatures ◽  
Age Determinations

Stratigraphic “displacements or dislocations” are coarse clasts and / or objects (such as unaltered remains or conodont-elements) slowly mobilizing or migrating vertically upward through a fine-grained matrix by a cryogenetic process known as “upfreezing” due to freezing temperatures. The process was originally established by periglaciologists and cold-climate geomorphologists who applied it only to unconsolidated, sedimentary deposits. In this study, the process is applied to the marine, pre-lithified, black shales of the Upper Devonian, Chattanooga Shale Formation, specifically in Tennessee, USA. The importance of this recognition is to alert paleontologists and stratigraphers about the strong possibility of inaccurate age-determinations made concerning coarse objects such as a conodont-element (denticles) (but not fossilized molds) because of their fossilized presence in age-determined, stratigraphic, rock levels when the apatite-composed denticles may have instead been initially deposited at a lower stratigraphic level during pre-lithification of the fine-grained, host-rock (shale) before the paleo-upfreezing process mobilized the denticles upwards. Many lines of evidences are given in this study towards apparent, predominant, freezing temperatures in the pre-existing, Chattanooga Sea of the Appalachian Basin, including particular, supposed, bioturbated, pre-lithified, organic black shale that is reinterpreted here as cryoturbated, pre-lithified, organic, black shale.

scholarly journals FORAMINIFERAL STUDY OF NKPORO SHALE EXPOSURES, CALABAR FLANK (SE NIGERIA): AGE AND DEPOSITIONAL ENVIRONMENT

2019 ◽  
Vol 4 (4) ◽  
pp. 369-378
Author(s):  
Asukwo Essien Itam ◽  
Victoria Inyang Emeka ◽  
Chimezie Ndunagum Emeka
Keyword(s):  
Organic Matter ◽  
Benthic Foraminifera ◽  
Depositional Environment ◽  
Hydrodynamic Conditions ◽  
Planktic Foraminifera ◽  
Southeastern Nigeria ◽  
Fine Grained ◽  
Sedimentary Deposits ◽  
Geological Age ◽  
Foraminíferos Bentónicos

Foraminiferal analysis of the sedimentary deposits of Nkporo shale exposed at PAMOL along Calabar/Odukpani Road, in the Calabar Flank, Southeastern Nigeria, was investigated in order to determine its geological age and paleoenvironmental conditions. The lithology is predominantly composed by shale with traces of siltstone and sandstone. Shale is generally light to dark grey, occasionally light brown, sub-fissile to fissile, moderately hard, carbonaceous, and slightly ferruginous. Results of foraminiferal analysis showed that the samples consist predominantly of arenaceous/agglutinated benthic foraminifera. Calcareous planktic foraminifera are absence and calcareous benthic taxa are almost absence of calcareous. The occurrence of the following foraminifera taxa Ammobaculite sp., Haplophragmoides sahariense, Haplophragmoides talokaense, Trochammina sp., Trochammina dustuna, Ammobaculites amabensis and Bolivina sp. suggest that sediments in the study area were deposited during the Maastrichtian age. The paleo-depositional-environment should occur in transitional marine settings, probably a marsh/lagoon. In the study area, calm hydrodynamic conditions prevailed. They favored the accumulation of fine-grained sediment and organic matter which gave rise to oxygen scarcity. The environment would be stressful for benthic foraminifera not only because of oxygen scarcity but also due to the variability of water salinity (hypo to hypersaline). ESTUDO DE FORAMINÍFEROS DOS FOLHELHOS DE NKORHO, CALABAR FLANK (SE DA NIGERIA): IDADE E AMBIENTE DEPOSICIONAL ResumoA análise de foraminíferos dos depósitos sedimentares do folhelho Nkporo expostos em PAMOL ao longo da estrada de Calabar/Odukpani, em Calabar Flank, sudeste da Nigéria, foi estudada tendo em vista determinar sua idade relativa e condições paleoambientais. A litologia é predominantemente composta por folhelho com camadas de siltito e arenito. O folhelho é, em geral, cinza claro a escuro, ocasionalmente marrom claro, sub-físsil a físsil, moderadamente consolidado, carbonáceo e levemente ferruginoso. Os resultados da análise dos foraminíferos mostraram que as amostras estudadas contêm predominantemente foraminíferos bentónicos arenáceos/aglutinantes. Não foram encontrados foraminíferos planctónicos, estando também quase ausentes táxons bentónicos com carapaça constituída por carbonato de cálcio. A ocorrência dos seguintes taxa Ammobaculites sp., Haplophragmoides sahariense, Haplophragmoides talokaense, Trochammina sp., Trochammina dustuna, Ammobaculites amabensis e Bolivina sp. sugerem que os sedimentos na área de estudo foram depositados durante o Maastrichtiano (Cretaceo superior). A sedimentação deverá ter ocorrido em ambiente marinho de transição, provavelmente em pântanos/lagoas. Na área de estudo, prevaleceram condições hidrodinâmicas calmas que favoreceram o acúmulo de sedimentos finos e matéria orgânica, que originou a escassez de oxigênio. O ambiente seria estressante para os foraminíferos bentónicos, não só devido à escassez de oxigênio, mas também devido à variabilidade da salinidade da água (hipo a hipersalina). Palavras-chave: Bioestratigrafia. Foraminíferos Bentônicos. Aglutinantes. Maastrichtiano. Cretáceo. Ambiente marinho de transição.

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