Sedimentary Environments

The materials analyzed in this paper were mainly collected from the Niehnieh Hsiongla Section in southern Tibet in 1995. The Jurassic of this area was divided into the Lower Jurassic Pupuga and Middle Jurassic Niehnieh Hsiongla formations. They are composed of marine clastic and carbonate rocks．The carbenate deposits account for 60 percent of the sedimentary rocks. According to textural origin classification, types of grains, sedimentary structures and fossils, the carbonate rocks can be recognized as three types consisting of twelve kinds of microfacies: grainstone (MG1 to MG8 microfacies), wackstone (GM1 and GM2 microfaeies) and mudstone (M1 and M2 microfacies). Each microfacies represents respectively different sedimentary conditions and environments. Four kinds of microfaties associations are classified on the basis of neighbouring and paragenetic relationship of microfaeies, as well as characteristies of fossil assemblages．Each microfacies association corresponds a designated sedimentary environment and its evolution. Although many types of sedimentary environments have been discerned in the study area, the sedimentary environment of the Early-Middle Jurasic is dominated by shoreface and shallow water sea. In this paper, the authors suggest that the Early-Middle Jurassic sea level changed periodically，and this change shows the characteristics of the initial stage of passive continental margin. In general, the Early-Middle Jurassic of the region was in a transgression period which is related to the expansion of the Himalayan ocean．

Key words：fossil carbonate, microfacies, southern Tibet, Jurassic

This work aims to identify sedimentary and basal rocks structures in the Sepetiba Bay Basin (Rio de Janeiro State, SE Brazil) located in the western portion of Guanabara Graben formed during the course of Paleocene tectonic activity. Two distinct geophysical tools were used to investigate the geological records by the integration of geological survey and geophysical data: Ground-penetrating radar (GPR) and Ground Magnetic survey. GPR results allowed to interpret and delimit subsurface layers of the basin. It was observed in the analyzed all sections, that the most superficial layers of the radargrams (about 8 meters; with Radar 100 Mhz) the presence of clay and silty sediment layers, related to a calm depositional environment and below 8 m sandy layers related to more energetic depositional environment were found. These sedimentological changes should be influenced by sea level oscillations and marine transgressions in this area. Magnetic ground survey allowed to identify basement r...

May, A. (1997a): Verwitterungsbeständigkeit und Verwitterung von Naturbausteinen aus Kalkstein. - Geologie und Paläontologie in Westfalen, vol. 48: p. 3-185, 94 figs., 2 tabs., pl. 1-11; Münster.

Abstract: Weathering durability and weathering process of natural building stones from the Lower Muschelkalk, the Upper Muschelkalk, and the Devonian have been investigated. Various properties of each building stone and its limestone material are measured (microscopy, SEM, porosity, ultrasonic velocity, geochemical methods). Defined microfacies types show clear differences in their weathering durability. The quantities of the cold water absorption, the Schurecht ratio (= ratio cold/boiling water absorption), and the residue insoluble by hydrocloric acid strongly affect the weathering durability. Together with the investigation of thin-sections, these properties enable prognoses about the weathering durability. A diagram of correlation between coldwater absorption and Schurecht ratio is developed, which is able to discriminate more durable and less durable limestones by a boundary line (Fig. 59-60).The limestones are mainly damaged by fissures which harm the unity of the stone. Probably these fissures are mainly based on frost phenomena. Connections between the sedimentary environment and the weathering durability are recognizable: generally limestones of the agitated (shallow) marine are more durable than other limestones.

Kurzfassung: Es wurden die Unterschiede in der Verwitterungsbeständigkeit zwischen verschiedenen Varietäten jeweils eines Kalksteins untersucht. Beprobt wurden Kalksteine des Muschelkalks im Raum Osnabrück-Bielefeld und des Devons im Sauerland in Bauwerken und Aufschlüssen. Eine neue Klassifikation des Verwitterungszustandes von Kalkstein-Mauersteinen wurde entwickelt. Die Oberflächenschäden auf der Außenseite sind nur ± gering und stellen bloß ein "kosmetisches" Problem dar. Die Stärke der Schädigung des inneren Zusammenhaltes des Mauersteins durch Risse ist viel wichtiger, da sie die Sicherheit und Stabilität des Bauwerks gefährdet. Die Untersuchung von Dünnschliffen ermöglichte es, insgesamt 17 Mikrofaziestypen zu definieren und erstmalig Unterschiede in der Verwitterungsbeständigkeit zwischen den verschiedenen Mikrofaziestypen eines Kalksteins zu erkennen. Kalksteine, die in ± turbulentem (und damit ± flachem) Meereswasser abgelagert wurden, sind tendenziell verwitterungsbeständiger als solche aus anderen Ablagerungsräumen. Mit der Auftriebsmethode wurden wichtige Porositätsparameter festgestellt. Freiwillige Wasseraufnahme und Schurecht-Ratio (= Quotient freiwillige Wasseraufnahme / effektive Porosität) beeinflussen die Verwitterungsbeständigkeit sehr stark, wenn ihre Größe zunimmt, nimmt die Verwitterungsbeständigkeit ab. Die Ultraschall-Untersuchungen zeigten, daß in Kalksteinen Spannungen viel weiter geleitet werden als in Sandsteinen und deshalb zu (lang aushaltenden) Rissen führen. Die rasterelektronenmikroskopische Untersuchung erlaubte Aussagen über einzelne Aspekte des Verwitterungsprozesses. Die im salzsäurelöslichen Gesteinsanteil gemessenen Element-Konzentrationen spielen keine Rolle für die Verwitterungsbeständigkeit der Kalksteine.  Die Verwitterungsbeständigkeit der bearbeiteten Kalksteine wird am stärksten von freiwilliger Wasseraufnahme und Schurecht-Ratio beeinflußt. Der Einfluß des Gehaltes an salzsäureunlöslichem Rückstand ist erheblich geringer. Darüber hinaus spielen auch die Merkmale Feinschichtung und Kristallgröße (Mikritl Sparit) eine gewisse Rolle. Die Entwicklung von Stylolithen hat nur nachrangige Bedeutung. Einen sehr großen praktischen Nutzen für Prognosen über die Verwitterungsbeständigkeit verspricht die erstmalig ermittelte Grenzlinie Schurecht-Ratio/freiwillige Wasseraufnahme, die unabhängig vom Probenkollektiv überdurchschnittlich und unterdurchschnittlich verwitterungsbeständige Kalkstein-Mauersteine mit ziemlich großer Schärfe voneinander trennt. Darauf aufbauend wurden leicht durchzuführende Verfahren zur Auswahl besonders verwitterungsbeständiger Kalksteine entwickelt. Im Gegensatz zur vorherrschenden Literaturmeinung werden Kalksteine im wesentlichen durch Risse geschädigt, die wahrscheinlich aufgrund von Frosterscheinungen (bzw. Frost-Tau-Wechsel-Prozessen) entstehen und hauptsächlich durch Frostsprengung vergrößert werden. Da die Schädigung der Gesteinsoberfläche ± gering ist, kann die chemische Verwitterung für Kalksteine nicht wichtig sein. Hierdurch unterscheiden sich Kalksteine in ihrem Verwitterungsverhalten sehr stark von Kalksandsteinen.

Despite the coming into force of the Algerian Littoral Law 02/2002, which aimed the protection of the coast and a sustainable use of its resources, construction projects have been authorized on brittle unstable lithology. Relating to this, Kharrouba experienced a tremendous change during the period 2004-2012 due to a massive urbanization. Accordingly, expert’s reports concerning the sustainability of construction projects as required by the Law 01-03-2003, were not sufficient. In this work, we analyzed the morphological coastal transformation of Kharrouba between 1989 and 2016 with particular interest in the decline of the dune due to a strong urban growth. For this purpose, a topographic map and Google Earth Pro pictures were used and processed in a geographical information system (SIG). The results of the diachronic analysis and the evolution of the coastal dune showed that the dune surface increased 23.82 % between 1989 and 2004; a period marked by a low construction activity. On...

This work analyses lead concentrations and isotope ratios 204Pb,206Pb,207Pb,208Pb, determined by leaching and total dissolution techniques from surface bottom sediment samples collected in the western sector of Sepetiba Bay, Rio de Janeiro (SE Brazil). The main aim of this work was to identify possible sources of Pb, particularly those related to anthropogenic activities for the study area located in the external region of this bay. Isotope ratios of 206Pb, 207Pb ranged from 1.160 to 1.259 for the total dissolution technique and from 1.175 to 1.188 for the leaching technique. The Pb isotope signature of the surface sediments of the western sector of Sepetiba Bay were compared with that obtained in other studies performed in Sepetiba Bay, including records of pre- and pos-industrial activity, and in other Brazilian regions. The isotope signature of the analyzed sediments in the western sector of Sepetiba Bay is similar to that obtained in previous works realized in the eastern and no...

The section between the 7 and 11 electric markers in the Aratu Stage of the Recôncavo Basin (Lower Cretaceous) has been studied in order to perform a stratigraphic analysis. This section bear reservoir rocks known as Imbé, Cambuqui and Miranga sandstones. It produces petroleum in fields like Miranga, Araçás, Taquipe, Miranga Norte and Imbé.The isopach map showed a general trend of increased subsidence for south and southeast. A series of structural lows surround the platform region known as Quiricó High. Southwestward, the Taquipe Canyon is an indication of the lake deepening in that region.In terms of depositional systems, it was interpreted that the Aratu Stage presented a river-dominated deltaic system all over its depositional history. In the proximal regions, located to the north and northwest, the main facies belong to the fluvial and delta plain associations and to the delta front and prodelta in the most distal system. The isolithic map and the sand percentage map indicates ...

A new methodology based on a portable X-ray fluorescence (pXRF) was applied in this work to analyze the geochemical dispersion halo of a sulfide mineralization along the Bule Stream sediments (Ouro Branco, Minas Gerais State, Brazil). The study area, located in the Iron Quadrangle (QF), has an important sulfide occurrence of antimony and zinc, which was explored between 1920s and 1930s. Stream sediment samples were collected along the Bule Stream and from some of its tributaries. Aluminum, Fe, Ca, Mg, Mn and Ti contents were obtained by the pXRF “mining mode” and quantified in percentage (%), while the results for Cu, Zn, Pb, As, Cr, Ag, Sb and Sr were carried out by the pXRF “soil mode”, quantified in parts per million (ppm). The statistical treatment of data by Spearman correlation based on geochemical data and some sediment features were discussed, such as the geochemical affinities between the analyzed elements and supergene processes which control the elemental dispersion. Alum...

The coastal areas, the most populated regions in the world, are those which have undergone the greatest human influence. In Brazilian southeastern coast, the region around Guanabara Bay (GB) is one of the most densely populated, with large cities, such as Rio de Janeiro and Niteroi, and is highly industrialized. Due to anthropic activities tones of effluents, waste and sewage is daily released in GB. Despite, several works have been performed aiming to study the current and past human influence in GB, the sources of pollutants that have impacted this bay since the late nineteenth century. This work is a new contribution aiming to identify the main sources of pollution in the northern/northeast region of GB using stable isotopes of lead (Pb) and metal concentrations during the last decades. It analyses results obtained along the core T3 collected in the northeast region of Guanabara Bay, near the Guapimirim Environmental Protected Area (known as Apa de Guapimirim), a mangrove fringe....

This study intends to evaluate baseline concentrations of chemical elements for unpolluted sediments of Sepetiba Bay (SE Brazil). It analyzes the concentrations of potentially toxic elements (PTE) and other chemical elements (by Inductively Coupled Plasma Mass Spectrometry and Inductively Coupled Plasma Emission Spectrometry) from the upper part of the SP2 drillcore (or 2-SPT-1-RJ; with 50.30 m length), collected on the margins of Sepetiba Bay (at latitude 22° 55'S and longitude 43° 46'W). This core was described and sampled. Textural, mineralogical and geochemical analyses were performed in 17 sediment levels. The sediment layers of interest were selected, considering the period in which they were deposited, before high anthropic influence in the area, and on sediment grain-size. Only the muddy levels were selected, since fine sediments generally tend to have higher elemental concentrations. Foraminiferal occurrence was also analyzed in the selected layers. The results indi...

El propósito principal de este trabajo es establecer un modelo geomorfológico que sintetice la dinámica del sistema estuarino de la desembocadura del río Hueque. Para el desarrollo del modelo se realizaron trabajos de campo en los que se recolectaron muestras de sedimentos de los ambientes depositacionales identificados, así como mediciones de las dimensiones de éstos, pendientes de playa, batimetría, oleaje y mareas. Se midieron parámetros físicos y químicos del agua como temperatura, pH, salinidad, conductividad eléctrica y transparencia. El trabajo de laboratorio se fundamentó en los análisis de textura, carbonatos, materia orgánica, minerales pesados y mineralogía por difracción de rayos X de las muestras de sedimentos. Se analizaron datos de clima, red de drenaje, mareas y oleaje y se realizó una fotointerpretación detallada del área. El estuario del río Hueque se comporta similar a un caño de marea, con aguas mezcladas y sin estratificación, fuerte tendencia a la hipersalinidad y pH entre neutro y ligeramente básico. Sobre la base de los factores y los procesos implicados, las características sedimentológicas de los ambientes depositacionales y el desarrollo y evolución del área, se concluyó que la desembocadura del río Hueque puede ser definida como un sistema estuarino de edad reciente.

This work analyses lead concentrations and isotope ratios 204Pb,206Pb,207Pb,208Pb, determined by leaching and total dissolution techniques from surface bottom sediment samples collected in the western sector of Sepetiba Bay, Rio de Janeiro (SE Brazil). The main aim of this work was to identify possible sources of Pb, particularly those related to anthropogenic activities for the study area located in the external region of this bay. Isotope ratios of 206Pb, 207Pb ranged from 1.160 to 1.259 for the total dissolution technique and from 1.175 to 1.188 for the leaching technique. The Pb isotope signature of the surface sediments of the western sector of Sepetiba Bay were compared with that obtained in other studies performed in Sepetiba Bay, including records of pre- and pos-industrial activity, and in other Brazilian regions. The isotope signature of the analyzed sediments in the western sector of Sepetiba Bay is similar to that obtained in previous works realized in the eastern and no...

This work is based on a compilation of benthic foraminiferal data collected in the Aveiro Lagoon and in the adjacent continental shelf and upper slope (center of Portugal). It intends to provide an overall analysis from transitional to the outer continental shelf of the occurrence and distribution of species in living and to present updated taxonomic data and illustrations of most of the species found in the in the Aveiro Lagoon and in the adjacent continental shelf including in total assemblages. Cluster analysis (CA) and Principal Components Analysis (PCA) interpreted as depth functions allow us to identify the main species in different ecoenvironments and sectors of the study area. The most unusual living assemblage was documented in the lagoon inlet under very strong tidal currents activity, composed mostly by the following species (both in living and total assemblages): Rotaliammina concava, Lepidodeuterammina ochracea, Quinqueloculina seminula, Gavelinopsis praegeri, Paratroch...

This article aims to advance in the knowledge of the relationships between the sand cycle and the behaviour of small river mouths (outlets) flowing into sandy beaches in the Río de la Plata estuary, Uruguay. The bars of these watercourses respond quickly with processes of erosion and/or migration of the channel when the "sand cycle" (coastal sedimentary balance) undergoes modifications, due to i) the effect of the fixation of dunes (sediments) by afforestation with exotic species and ii) the construction of infrastructure. Two watercourses were analysed: the Pando River and the Carrasco Creek that both have received different impacts and suffered modifications, not only in the sediment flow but also in their hydrological regime. A multitemporal analysis was based on a series of aerial photos and cartography since 1928, a background review, and the support of documents and chronicles. The data obtained were analysed statistically. Results evidence a significant loss of beac...

Sediments preserve environmental information at the time of deposition which is a useful tool to evaluate the extent of the environmental change from its pristine condition. We evaluated historic environmental trends in the sedimentary record by analysing three sediment cores collected within the freshwater region of Patos Lagoon (southern Brazil). As, Ba, Cr, Cu, Ni, Pb, and Zn were analysed by inductively coupled plasma optical emission spectrometry. C/N ratios and δ13C values were also determined. Contamination indices such as Enrichment Factor, Geoaccumulation Index, Sediment Pollution Index and Pollution Load Index were calculated to evaluate the influence of anthropic activities. Multiple-elemental indices showed a general overview of the environmental conditions of the lagoon throughout time. Furthermore, single-element indices explained which elements triggered the observed changes in the environmental trends. Near Camaquã River mouth, we inferred fairly undisturbed conditio...

The Irati Formation (Lower Permian of Paraná Basin) is a lithostratigraphic unit characterized by the rhythmic alternation between carbonates, shales, and marls, interpreted as low energy deposits with eventual storm deposition. Despite many studies that were developed at Irati Formation in the south and southeast part of Brazil, a better comprehension of the geological processes that took place in the northern portion is still necessary. In this sense, we present a detailed sedimentological analysis coupled with organic carbon content for the Permian rocks of Paraná Basin at Goiás State. Based on sedimentological descriptions, six facies association, including low to high energy facies, were described and interpreted as deposits of an inner to outer ramp domains of a homoclinal ramp system. Our data also indicate a relationship between changes in facies association and organic carbon content variation. TítuloANÁLISE DE FACIES SEDIMENTARES APLICADA À FORMAÇÃO IRATI NA ÁREA NORTE DA ...

Igneous intrusions in sedimentary basins are commonly related with mineralogical association changes in host-rock. At Sapopema region (Paraná State, southern Brazil), an extensive diabase sill (associated to Serra Geral Formation) was emplaced in pelitic-carbonate succession during post-Triassic. The sedimentary host-rock association includes mostly shale, siltstone and carbonate of the Permian Irati Formation. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) data revealed that heat transfer was not enough to cause modifications in mineral assemblage of the Taquaral Member (quartz + albite + muscovite + illite + kaolinite + chlorite). However, mineralogical content from Assistência Member presented changes probably caused by the intrusion of diabase sill (talc + pyrophyllite + calcite). Talc and calcite were formed due to the reaction between dolomite and quartz, while pyrophyllite was the product of reaction between kaolinite and ...

The Lameta sediments covering the geographical area of about 5,000 km2 in central and western India are well documented for their sedimentological and paleobiologic aspects in last four decades. Occurrences of dinosaurian remains including bones, coprolites, eggs, eggshells and nests in mainly arenaceous lithounits of the successions exposed at various localities have been widely used as a significant tool for precise reconstructions of paleogeographic and paleoenvironmental set-up during the Maastrichtian period. Based on sedimentological and paleobiologic aspects, earlier it was considered that the Lameta sedimentation took place in only five inland basins viz., i) Nand-Dongargaon, ii) Jabalpur, iii) Sagar (Saugor), iv) Ambikapur-Amarkantak and v) Balasinor-Jhabua. Recently a sixth inland basin has been added by Mankar and Srivastava, Salbardi-Belkher, which has been highlighted because of its bearing on the overall picture of Lameta sediments deposition, dinosaur inhabitation and...

Paleoenvironmental reconstructions in coastal environments have been carried out using indicators of relative sea level oscillation (RSL), among them, mollusk shells, beachrocks and sedimentary records. Data from eleven geological-geotechnical drilling cores (from 15 m to 30 m long) distributed along the Ipanema - Leblon coastline and on the edge of the Rodrigo de Freitas Lagoon and respective stratigraphic profiles were analyzed in this work. Eleven radiocarbon ages obtained from shell samples calibrated to eliminate the effect of reservoir were used to perform the time evolution of the study area.The obtained results allowed to identify five distinct stages on the sedimentary evolution of the Southern Zone of the Rio de Janeiro City related to the Holocene RSL variations: the first stage under continental environmental conditions, with sea level approximately 4.5 m below the current; the second stage corresponding to a paleo-cove formed due to the sea level rising; the third stage...

The Irati Formation (Lower Permian of Paraná Basin) is a lithostratigraphic unit characterized by the rhythmic alternation between carbonates, shales, and marls, interpreted as low energy deposits with eventual storm deposition. Despite many studies that were developed at Irati Formation in the south and southeast part of Brazil, a better comprehension of the geological processes that took place in the northern portion is still necessary. In this sense, we present a detailed sedimentological analysis coupled with organic carbon content for the Permian rocks of Paraná Basin at Goiás State. Based on sedimentological descriptions, six facies association, including low to high energy facies, were described and interpreted as deposits of an inner to outer ramp domains of a homoclinal ramp system. Our data also indicate a relationship between changes in facies association and organic carbon content variation. TítuloANÁLISE DE FACIES SEDIMENTARES APLICADA À FORMAÇÃO IRATI NA ÁREA NORTE DA ...

This study reconstructs Holocene hydrodynamic changes on the outer shelf off Uruguay by examining deposits from a morphological terrace on the uppermost continental slope (250 m water depth). Seismo-acoustics, litho- and chronostratigraphy, granulometry, and Neodymium isotopy were applied to three sediment cores. The 9.5-m thick terrace sediment record, documenting the past 11.5 cal ka BP, provides exceptional insight into the transport and settling mechanisms of the sand injected from the shelf into the open ocean. The sandy outer shelf is identified as the principal sediment origin. Contouritic bottom currents do not significantly affect deposition on the terrace. Instead, the sandy sediment gets spilled over the shelf edge in the form of suspension clouds, spreading uniformly over the whole terrace. The suspended sand does not transform into high-concentration gravity-driven bottom flows but rains down onto the terrace as a quasi-permanent material supply. This observation sugges...