Sedimentological Aspects Research Articles

Tendance Evolutive Et Bilan Des Sediments De Profondeur De 2008 A 2018 : Cas De La Lagune Adjin (Littoral De La Cote D’ivoire)

The Adjin lagoon was studied in its morphological, hydrological and sedimentological aspect. This study made it possible to understand the morphological modifications of the bottom and surface of the Adjin lagoon based on the production and superposition of two bathymetric maps from the years 2008 and 2018. In addition, this study makes it possible to know the estimation of the speed, volume of sediments eroded and deposited. From a morphological point of view, the Adjin lagoon is characterized by depressions and shoals. The depressions are at the origin of the formation of “V” shaped channels. Shoals are characteristic of “U” shaped channels. Depths less than 11 m occupy 2/3 of its surface area. Particularly during the last ten years, the Adjin lagoon has suffered erosion and deposition phenomena. The rate of eroded sediments is estimated at approximately - 1.65 hm³ over an area of 7.9 km2 while in the same period, the rate of sediments deposited is +3.42 hm³ over an area of 12.3 km2 . This results in a sediment budget of +1.77 hm³. The evolutionary trend of sedimentary dynamics in the Adjin lagoon is therefore more favorable to fattening than to erosion. The sedimentation rate is estimated at approximately 2.7 cm/year. The morphological analysis and the sedimentary balance provide crucial information on the good management of fresh water and aquatic resources of the Adjin lagoon. Therefore, populations living near this body of water must limit their domestic activities in order to preserve the quality of this water

Characterisation and Spatial Distribution of Sediments on the Cote d'Ivoire Continental Shelf (Abidjan to Assinie)

The continental shelf of Côte d'Ivoire, particularly the Abidjan-Assinie area, has been studied due to its importance and potential, although little research has focused on its sedimentological aspects. Sediment samples were collected using a Shipeck grab, and grain size analyses revealed the presence of fine sands, medium sands, and rarely very fine sands. These sands exhibit a skewness toward finer grains, which is abundant, followed by nearly symmetrical and highly skewed towards finer grains, describing five (05) types of sorting. Deposited in a more or less turbulent environment or due to excess load, the sands have been transported in water — as indicated by their shiny, abraded state — by saltation, suspension, and mixed modes. These sands preferentially reside in a continental domain.

Facies models for rocky shorelines and their application to transgressed basement highs in the North Sea

Rocky shorelines form where basement highs are eroded and flooded during marine transgressive events. Although the Mesozoic North Sea rift generated numerous platform margins and rotated fault blocks that acted as basement highs, rocky shoreline deposits have not previously been reported in this region. Rocky shoreline deposits are usually represented in the rock record by thin conglomerates overlying major unconformities. They are typically characterized by their ichnological aspects rather than by their depositional facies. This study used the sedimentological aspects of modern and Miocene rocky shorelines from Spain and Austria to create facies models, which were then applied to the recognition of rocky shorelines in the Mesozoic of the Central North Sea. Our results demonstrate that structureless, clast-supported, poorly to moderately sorted conglomerate–breccia deposits are associated with competent basement lithologies, which produce hard, resistant coastal cliffs around previously overlooked volcanic centres in the subsurface of the North Sea. The basement lithologies in most of the Central North Sea favoured the formation of softer coastal cliffs, with less resistant lithologies that did not generate or preserve gravel-sized particles. These softer coastal cliffs were mostly characterized by low-angle, unconformity-bounded sandstones and fine-grained deposits, precluding the preservation and recognition of Mesozoic rocky shores in much of the North Sea's stratigraphic record.

Facies characterisation and stratigraphy of the upper Maastrichtian to lower Danian Maastricht Formation, South Limburg, the Netherlands

Abstract The Maastricht Formation is a mostly calcarenitic unit that belongs to the Chalk Group but is unlike the typical North Sea chalk in that it is much coarser and at times contains a significant terrigenous component. The formation was deposited between the late Maastrichtian and the early Danian in a proximal zone of the Chalk Sea immediately north of the Anglo-Brabant and Rhenish massifs. The formation crops out in South Limburg, the Netherlands, in the German state of North Rhine–Westphalia, near Aix-la-Chapelle (Aachen), and in the Belgian provinces of Liège and Limburg, and it is present in the subsurface in the Campine Basin and in the Roer Valley Graben, in Belgium and the Netherlands. The often spectacular fossil content of the Maastricht Formation has been extensively studied but its sedimentological aspects remain understudied. Indeed, the lithostratigraphy of the formation is largely informal and based on the abundance and morphology of flint and on the quantification of fossil content. The paucity of facies studies and the lack of a lithostratigraphic framework based on modern facies studies hampers stratigraphic correlation between outcrops and, more importantly, boreholes. A facies characterisation and facies-based lithostratigraphic framework of the Maastricht Formation in South Limburg is particularly urgent because groundwater is abstracted from aquifers in the formation and geological models currently in place fail to predict facies heterogeneity and, consequently, aquifer properties. We studied eight outcrops of the Maastricht Formation across South Limburg and carried out a (micro)facies analysis of the outcrops. We show that the Maastricht Formation can be subdivided into three lithofacies and five microfacies. The lithofacies reflect the traditional subdivision of the formation into Maastricht and Kunrade limestones. Our results suggest that the current subdivision of the Maastricht Formation into six members is untenable. The formation is best subdivided into lower and upper members. The Kunrade limestone should be afforded the status of formation. We interpret the Maastricht Formation as having been deposited in an epeiric ramp, in which facies distribution was controlled by water temperature, nutrient levels and storminess. The (micro)facies of the Maastricht Formation can be organised into two depositional stages: stage 1, representing the lower part of the formation, is characterised by heterozoan carbonates deposited under cooler, mesotrophic conditions in a nutrient-rich, more proximal region of the epeiric sea; stage 2 is characterised by heterozoan-photozoan carbonates deposited in a warmer and stormier environment with slightly lower nutrient levels.

Ichnology and sedimentological aspects of the Floriano Formation (Miocene of the Resende Basin), southeast of Brazil

Many previous studies identified depositional systems for the Resende Basin using sedimentological and petrographic techniques. However, the lack of ichnological research leaves a gap in our understanding of paleoenvironment and paleoecology of this basin. Therefore, this study reports the first occurrence of trace fossils in the Floriano Formation (Miocene) and suggests more refined paleoenvironmental interpretations for this unit. We only observed ichnofossils in an outcrop on the RJ-161 road in Resende Municipality, Rio de Janeiro State. The deposit represents a floodplain overlayed by a crevasse splay, both sedimented in a meandering fluvial context. Trace fossils of terraphilic organisms – represented by Taenidium isp., Planolites isp. and Arenicolites isp. – were found in the fine-grained sediments of the outcrop. This ichnocoenosis is composed of feeding (fodinichnia), locomotion (repichnia) and/or habitation (domichinia) structures produced by worm-like invertebrates. The ichnotaxonomic assemblage consists of the first record of Scoyenia ichnofacies for a typical meandering fluvial system in Brazil. Keywords: continental ichnology, sedimentology, ichnofacies, paleoenvironment.

Residual rocky forms in the landscape of the Outer Carpathians (Silesian Beskid Mts, Poland) – geotourist and sedimentological case study

This study investigated residual landforms developed within of the flysch bedrock in the Outer Western Carpathians as sandstone-to-conglomeratic tors. The studied relic rocky forms are locally exposed on the valley slopes in the top and plateau parts of the Silesian Beskid Mts. The cognitive values of such relic landforms, especially in the context of their morphogenetic traits and shaping of their macro- and microrelief, are well known and described. In contrast to epigenetic processes, the sedimentological aspect of the origin of such siliciclastic rocky deposits is still subject to different approaches in terms of terminology and interpretation. Thus, the aim of this study is to describe the conditions of environmental settings and character of the sediment transport and deposition processes from gravity flows, and to present a depositional system model for such a variety of flysch deposits. This study also attempts to present geotourist and geoeducational attractiveness of the tors against the background of regional geodiversity, geoheritage, and geoprotection. The results yielded a synthetic morpho-litho-sedimentological and geotouristic specification of the rocky forms analysed. The residual rocky landforms are polygenic geomorphological elements developed as a consequence of multistage and different scale of morph-forming activity operating on the basis of litho-sedimentological and tectonic assumptions under the influence of denudation processes.

Residual rocky forms in the landscape of the Outer Carpathians (Silesian Beskid Mts, Poland) - geotourist and sedimentological case study

This study investigated residual landforms developed within of the flysch bedrock in the Outer Western Carpathians as sandstone-to-conglomeratic tors. The studied relic rocky forms are locally exposed on the valley slopes in the top and plateau parts of the Silesian Beskid Mts. The cognitive values of such relic landforms, especially in the context of their morphogenetic traits and shaping of their macro- and microrelief, are well known and described. In contrast to epigenetic processes, the sedimentological aspect of the origin of such siliciclastic rocky deposits is still subject to different approaches in terms of terminology and interpretation. Thus, the aim of this study is to describe the conditions of environmental settings and character of the sediment transport and deposition processes from gravity flows, and to present a depositional system model for such a variety of flysch deposits. This study also attempts to present geotourist and geoeducational attractiveness of the tors against the background of regional geodiversity, geoheritage, and geoprotection. The results yielded a synthetic morpho-litho-sedimentological and geotouristic specification of the rocky forms analysed. The residual rocky landforms are polygenic geomorphological elements developed as a consequence of multistage and different scale of morph-forming activity operating on the basis of litho-sedimentological and tectonic assumptions under the influence of denudation processes.

3-D quantitative seismic imaging of tectonically-influenced Middle-Eocene carbonates stratigraphic traps of SE-Asian basins using spectral decomposition: Implications for hydrocarbon exploration

Carbonates form energetic stratigraphic petroleum systems. The tectonic uplifting and subsidence significantly affect the overall reservoir configurations. During these stratigraphic scenarios, the prediction of accurate thickness for subsidence and uplifting zones becomes challenging. The band-limited seismic data interpretation tools fail to detect the zones of thinning and thickening of sediments along with uplifting and subsidence. The band-limited seismic does not have the tuning frequency, that can be used to predict the accurate vertical thickness of the thin-bedded carbonates. The constant wavelet-based transformation tool (WT) and inverted reservoir simulations have robust implications for the quantification of any depositional system. Especially, when the reservoir is shallow marine, the application of WT has resolved a variety of stratigraphic traps in terms of their seismic and sedimentological aspects. The stratigraphic traps are comprised of thin beds, which are not resolvable on conventional seismic. These traps require a specific tuning frequency, which is the key ingredient for the prediction of oil and gas inside them and can only be obtained by the implementation of the WT tool. Therefore, the WT, static stratigraphic thickening wedge models (SSTWM), and WT–based instantaneous spectral thickness modeling (ISTM) tools are applied on a gas field in Indus Basin, Pakistan. The 43-Hz CWT images the densely fractured and faulted network within the shoal reservoir limestone lenticular lens (SRLL) with an aerial extent of 208 km2 in southwest-northeast orientations. The band-limited attributes revealed poor imaging of sub-surface carbonate systems. The 43-Hz wavelet-based SSTWM predicts a 15-m-thick coarse-grained SRLL along subsidence and a 12-m-thick fine-grained SRLL along uplifting zones. Post-stack processing at 43-Hz CWT tuning frequency predicts the 18 and 10 m thick sediments for SRLL along the subsidence and uplifting zone. The ISTM predicts a thickness of 31 m during subsidence within the SRLL and 14 m for uplifting zones. The 43-Hz tuning frequency-based processing at ISTM predicts enhanced thicknesses of 41 and 18 m for subsiding and uplifting sediments that are trapped inside the shoal limestone petroleum systems. The quantitative visualization of AI with the predicted thicknesses at ISTM has provided robust clues for imaging the internal stratigraphic architecture of the SRLL. The linear regression analysis remained a very successful tool for assessing the quantitative aspects of SRLL with a strong R2 > 0.95, which has implicated the real-time imagining of sea-level fall and rise. Only post-stack seismic data processing at 43-Hz found a very effective exploration tactic in predicting the enhanced thicknesses, and lateral continuity of the reservoir, and improved the S/N by removing the tuning effect of ambiguous lithology/fluids, which have accurately predicted the exact location along the subsidence zones. This workflow can act as an analogue stratigraphic exploration of remaining gas fields within Asian Basins and similar geological settings.

Provenance of the Lower Cambrian Khewra Sandstone: Implications for Pan-African Orogeny

This study describes the sedimentological aspects of the Lower Cambrian Khewra Sandstone, along with its lithostratigraphic correlation of globally distributed coeval red sandstones to decipher the imprints of Pan-African Orogeny. Despite the economic significance of Khewra Sandstone, the understanding of its environment of deposition, provenance and lower contact with the suite of igneous body namely Khewrite is poor. The Khewra Sandstone is an allostratigraphic unit bounded by unconformities. The upward coarsening sequence with abundant sedimentary structures and varying sedimentological properties of the topmost bed suggest that the Khewra Sandstone is tempestites deposited under fluvio-deltaic depositional environment. This sandstone is dominated by subarkoses, feldspathic litharenites and sublitharenites which were derived from the craton interior to recycled orogen provenance during the Pan-African orogeny under humid to semi-humid paleoclimatic conditions. The plutonic to metamorphic characteristics of framework grains suggest that the Bundlekhand Craton, Delhi Fold Belt and Aravalli Orogen rocks were the primary provenances. The lower and middle parts of the Khewra Sandstone are significantly affected by diagenesis while the diagenetic action in upper part is negligible and it acts as a potential hydrocarbon reservoir rock. The lithostratigraphic correlation suggests a worldwide series of rifting events before the deposition of Khewra Sandstone and the presence of Khewrite at lower contact marks a similar rifting event on the Indian plate.

Sabellaria alveolata versus Sabellaria spinulosa Reefs along the Italian Coasts: A New Methodological Proposal to Compare Different Growth Models

Sabellaria species are among the most important frame-builders in temperate, shallow marine areas. These polychaetes are suspension feeders able to build bioconstructions using sand and shell fragments cemented with a sticky mucous. Such feature makes these invertebrates “unusual bioconstructors”, as they do not produce calcium carbonate. Sabellaridae reefs are widespread in the Mediterranean and along the Atlantic coast of Europe, but their sedimentological aspects are still poorly known. Over short time intervals, these bioconstructions can rapidly alternate between phases of growth, stasis and destruction during different seasons. In this paper, we compare reefs of two Sabellaria species (S. alveolata—Ostia, Roma and Tyrrhenian Sea; S. spinulosa—Torre Mileto, Foggia and Adriatic Sea) found at two different sites along the Italian coast. We describe the morphology of worm tubes at the macro- and microscale. Similarities and differences are discussed based on eco-biological features and physical environmental conditions. This work shows a measurement and observation scheme for this type of bioconstructions that has been verified at both the macro- and microscale and which was shown to be useful for defining evolutionary trends of sabellarian bioconstructions. The monitoring parameters were identified and verified over a long period.

Upper Pleistocene–Holocene in the continental slope of the Cará Basin: an integrated analysis based on planktic foraminifera, sedimentological and geochemical aspects

This research addresses paleoclimatic variations using sedimentological, geochemical, and planktic foraminifera. The study was carried out in a survey core (ANP 1011) collected on the continental slope of the Icaraí Sub-basin (Ceará Basin), on the coast of the Municipality of Itapipoca, CE, Brazil. Particle size analysis, CaCO3 content, Ti/Ca and Fe/Ca ratios, and the analysis of foraminifera associations for biostratigraphic purposes were performed. Based on the relative abundance of planktic foraminifera, with indicators of warm and cold water throughout the studied cores, two biozones (Y: Upper Pleistocene and Z: Holocene), and two subzones (Z2 and Z1) were recognized. The data of sedimentological markers obtained confirmed the occurrence of more wet phases in northeastern Brazil during the early stages of the Holocene. The Ti/Ca and Fe/Ca ratios, as well as the geochemical and micropaleontological proxies, indicated a farther north displacement of the Intertropical Convergence Zone (ITCZ) in the Pleistocene–Holocene transition. This may have caused greater precipitation in the Northeastern region of Brazil, effectuating the entry of a high volume of terrestrial sediments directly into the ocean basin. Keywords: Quaternary biostratigraphy, marine sedimentation, ITCZ mobility, paleoclimate.

Changes in the hydro-sedimentary balance: Impacts of the use of a borrow pit in a low-order stream.

Construction of dams for hydroelectric power requires significant quantities of soil and rock, which are often extracted in borrow pits from adjacent regions. Although the effects of dams on stream processes has received significant attention, the effects of borrow pits has not. The main objective of this study was to analyze the geomorphological and sedimentological aspects of two second-order streams, one of which was directly affected by the borrow pit located upstream of its source (Pedra Branca stream). Flow rates were measured and cross-sections of 600m stretches in both streams were monitored over a hydrological year. At the same time, sediments from the bed of the channels and soils on their banks had their physical and chemical characteristics evaluated. Streams sediments differed in their chemical and organic matter composition. The mean particle size of the sediment particles was different between the reference and degraded streams. The water flow was very similar to both streams, only varying along the seasonal seasons. However, the fluvial channels presented great geomorphological differentiation, mainly downstream, due to the location of the Pedra Branca stream and its proximity to the borrow pit. Despite the great importance for the production of clean electric energy, the construction of hydroelectric plants promotes persistent impacts that affect structural and functional aspects of the adjacent aquatic habitats. Borrow pits used for the construction of projects become large sources of sediment for aquatic environments, affecting the drainage network of the hydrographic basin and the balance of river erosion, transport and deposition processes. The results show the need to review the intervention protocols in borrow pits and the environmental legislation that regulates their rehabilitation.

Sequence stratigraphic framework of the Upper Eocene–Oligocene succession, northwest Birket Qarun, Fayum-Egypt

The Upper Eocene–Oligocene sequence exposed northwest Birket Qarun; Fayum district covers two rock units, Qasr El-Sagha (Temple and Dir Abu Lifa members) and Gebel Qatrani formations were re-evaluated by sequence stratigraphy. Six depositional sequences were recognized based on facies geometry, and sedimentological aspects. The first sequence (Temple Member) was accumulated under marginal intertidal flat environment indicating highstand deposits. The second (the lower Dir Abu Lifa Member) displays a regressive sedimentary facies starting with progradational delta front environment reflecting lowstand deposits followed upward by a lagoonal environment indicating transgressive/highstand deposits. The third (the top of the Dir Abu Lifa Member) was accumulated under a low sinuosity stream reflecting lowstand deposits. The fourth which constitutes the topmost of Dir Abu Lifa Member initiating near-shore shallow marine points to transgressive sediments, followed upward by fluvial sediments reflecting highstand deposits. The fifth (the Lower of Gebel Qatrani Formation) accumulated as point-bar deposits demonstrating lowstand deposits. The last occupies the main of Gebel Qatrani Formation initiates with restricted riverine marking lowstand deposits, followed upward by several fining upward cycles that were accumulated in fluvial and flood plain conditions with evidence of tidal influence on sedimentation near its top denoting transgressive deposits. Several minor transgressive episodes accompanied by tidal influence on sedimentation are noticed near the top, which may reflect gradual subsidence of the Oligocene alluvial plain. The area is subjected to relative sea-level changes that show a similarity with the global sea level. The base-level fluctuations are mainly controlled by the regional tectonic setting.

Sedimentological, Lithostratigraphic, Clayey and Exoscopic Study of the Senonian Series of Arg N’Sidi Ali Ou Bourk, High Central Atlas of Morocco

The sedimentological study of the red formations (Senonian series) represents a challenge and an exciting subject that needs to be explored. This paper will present the sedimentological, stratigraphic, and paleogeographic aspects of the Upper Cretaceous of the ARG N'SIDIALI OR BOURK, Central High Atlas Morocco. In this region, a marker section was realized bed by bed and sampled in a very straightforward way in order to study stratigraphy, to describe, to interpret and to characterize the sedimentary environment of the senonian succession in the ARG N'SIDIALI OU BOURK region, more particularly the analysis of the clays by X-ray diffractometer (XRD) has allowed understanding the depositional environments of the Upper Cretaceous formations. Therefore, the Senonian of ARG N'SIDIALI OU BOURK corresponds to continental lagoon deposits. It is characterised by sedimentation in the continental environment (fluvial or flooded), with some rare marine ascents marked by the installation of whitish sandstone bars.

Causes and consequences of Oligocene-Miocene relative sea level change in Asia: An example from the Labuan Island (Sabah), Malaysia

Belait Formation: (A) Trough cross-bedded sandstone (fluvial) (B) Interbedded sandstone-mudstone (sandstone dominated) facies overlying mudstone facies (marine). • The Miocene Belait Formation in the Labuan Island formed due to forced regression. • The upper part of the Belait Formation indicates transgression and marine flooding. • The depositional environment changed during the Oligocene-Miocene in Sabah and Sarawak. • This was linked to regional tectonics and/or global relative sea level. • No record of paleoclimate shift like central Asia is inferred in this study. Labuan Island represents the emergent part of a north-eastward plunging anticline. The stratigraphic succession at Labuan is made up of four formations: the Crocker Formation, the Temburong Formation, the Setap shale Formation and the Belait Formation. The sedimentological aspects of the Labuan stratigraphic succession have been studied by several authors but the stratigraphic relationships between the formations is still a matter of conjecture. In this paper we have undertaken an outcrop based (1) sedimentary facies analysis of the Middle Miocene Belait Formation and (2) inferred the mode of stratigraphic sequence building of the Oligocene-Miocene successions. In significant contrast to the tide-storm interactive shallow-marine Belait Formation of Brunei and Sarawak, the Belait Formation of the Labuan island is made up of a lower fluvial and an upper shallow marginal marine to shelf facies association. The sedimentary succession from the Crocker, Temburong, Setap Shale and Belait formations represents a marine regression either due to a relative sea-level fall (forced regression) or to sediment supply exceeding the rate of sea-level rise (normal regression). The ~17 million years unconformity separating the fluvial facies association of the Miocene Belait Formation from the underlying shelfal sedimentary units (Oligocene Temburang and/or Setap shale formations) is a subaerial unconformity that is a consequence of rapid uplift and associated forced regression, and thus indicates the influence of regional tectonics on the mode of stratigraphic sequence building The change in paleocurrent pattern recorded by earlier researchers across the Oligocene-Miocene boundary also indicates tectonic tilt, and a change in sediment dispersal direction because of upliftment. The upper marginal marine facies association of the Belait Formation indicates transgression and the thick shelfal mudstone unit that overlies the marginal marine deposit indicates subsequent maximum flooding. Our sedimentological and stratigraphic analyses reveal that the shift in depositional environment during the Oligocene-Miocene transition is linked to regional tectonics and consequent sea level change and unrelated to paleoclimatic shift.

Stratigraphic and sedimentological aspects of the worldwide distribution of Apectodinium in Paleocene/Eocene Thermal Maximum deposits

Abstract The Paleocene/Eocene Thermal Maximum (PETM) is characterized by pronounced global warming and associated environmental changes. In the more-or-less two decades since prior regional syntheses of Apectodinium distribution at the PETM, extensive biological and geochemical datasets have elucidated the effect of rising world temperatures on climate and the biome. A Carbon Isotope Excursion (CIE) that marks the Paleocene/Eocene Boundary is associated with an acme of marine dinocysts of the genus Apectodinium in many locations. Distinctive foraminiferal and calcareous nannofossil populations may also be present. For this updated, dinocyst-oriented view of the PETM, data from worldwide locations have been evaluated with an emphasis on stratigraphic and sedimentological context. What has emerged is that a change in lithology is common, often to a distinctive siltstone or claystone unit, which contrasts with underlying and overlying lithotypes. This change, present in shallow marine/coastal settings and in deep-water turbidite deposits, is attributed to radical modifications of precipitation and erosional processes. An abrupt boundary carries the implication that some time (of unknowable duration) is potentially missing, which then requires caution in the interpretation of the pacing of events in relation to that boundary. In most instances an ‘abrupt’ or ‘rapid’ CIE onset can be attributed to a data gap at a hiatus, particularly in shallow shelf settings where transgression resulted from sea-level rise associated with the PETM. Truly gradational lower boundaries of the PETM interval are quite unusual and, if present, are poorly known so far. Gradational upper boundaries are more common, but erosional upper boundaries have been reported. Taxonomic changes have been made to clarify identification issues that have adversely impacted some biostratigraphic interpretations. Apectodinium hyperacanthum has been retained in Wetzeliella , its original genus. The majority of specimens previously assigned to Apectodinium hyperacanthum or Wetzeliella ( Apectodinium ) hyperacanthum have been reassigned to an informal species, Apectodinium sp. 1. Dracodinium astra has been retained in its original genus as Wetzeliella astra and is emended.

Sedimentology of sandy beaches of Santa Catarina Island, SC, Brazil

The sedimentological aspects of the beaches of Santa Catarina island: Cacupe Grande, Jose Mendes, Lagoinha, Mole, Matadeiro and Solidao were seasonally monitored. The used methods consisted on the sampling of surface sediments from the backshore, beach face and foreshore morphologic zones, in order to analyze parameters such as mean size, standard deviation, skewness, kurtosis and roundness. The beaches from Northwest and Southwest coasts, Cacupe Grande and Jose Mendes, respectively, adjacent to the North and South bays, protected from waves hydrodynamic action, are composed by coarse to very coarse sand, poorly selected, angular, typical of immature depositional environments. The Lagoinha and Matadeiro beaches, from the North and Southeast coasts, respectively, represents semi-exposed beaches, composed with fine sand, well sorted, rounded, which is typical of supermature depositional environments. The Mole beach, on the Northeast coast, represents an exposed beach from a supermature depositional environment, with medium sandy grains, moderately sorted and well-rounded. The Solidao beach, on the South coast, also considered exposed and supermature, has fine sandy grain, well selected and rounded. There were no significantly seasonal variations in any of the parameters.

Evaluation of freshwater benthic communities: a case study in an urban

The environmental damage suffered by urban water bodies and the need for public water supply result in a greater interest in techniques that enable water treatment in an efficient and ecological way, such as River Bank Filtration (RBF). This technique uses the soil as a filtering medium, as well as the biological activities of organisms that dwell in the Hyporheic Zone (HZ), the zone of interaction between the surface water body and its underlying aquifer. Knowledge of sediments and hyporheic organisms is indispensable to study RBF. The present paper aimed to characterize the HZ of the middle section of Beberibe river (Pernambuco State, Brazil) in its sedimentological and biological aspects, with sampling druing the rainy and dry seasons, in two distinct sampling sites, one in a conserved area and the other in a highly urbanized area. Biological characterization was performed at the level of large taxonomic groups of meiofauna, accounting for 982 individuals, with the three most abundant taxa being Nematoda, Annelida, and Rotifera. Permutational Analysis of Variance (PERMANOVA) statistical tests were performed, showing significant differences for the season and point factors (p < 0.05) in relation to abundance. The highest concentration of individuals and total organic matter were seen in the rainy season, especially at the point located in the urbanized area. With sedimentological characterization by grain size tests of the hyporheic sediments, the predominance of silt was observed during the rainy season, and sandy during the dry season. It was concluded that the main factor that influenced the structure of the meiofauna community was the release of domestic effluents. The information obtained by the present work helps to understand some features of the HZ, which is essential for RBF or other techniques that use the interstitial matrix.

Jurassic neoselachian sharks from the Mt Nerone Pelagic Carbonate Platform (Umbria-Marche Apennine, Italy): a further constrain for the palaeoecology related to PCP systems

ABSTRACT The Mt Nerone area hosts a Jurassic-Cretaceous Pelagic Carbonate Platform (PCP)-basin succession in the Umbria-Marche Domain (Central Italy). Despite being studied thoroughly on sedimentological and geological aspects, wide-spectrum palaeocological studies are currently missing for this peculiar setting. While several studies on the invertebrate fauna of PCP system are available, the vertebrate fauna remained for a long time mostly unknown. Recently a renewed interest has been directed to vertebrate remains of the region. To date, an articulated dentition and some other tooth fragments of hybodont sharks and neoginglymodian actinopterygians have been described from the Jurassic of the Mt Nerone area. These taxa indicate the existence of diverse durophagous ecological niches available for durophagous fauna in the PCP system, linked to the abundant hard-shelled invertebrate fauna inhabiting the structural highs. In the present contribution we report and describe remains of neoselachians Synechodontiformes from five localities of the Mt Nerone area. The new material, represented by several isolated teeth and referred to as Sphenodus spp., testifies an additional trophic level for the Jurassic palaeoecology in the Umbria-Marche Domain, throwing new light on the peculiar PCP-basin ecosystem.

L'uomo universale del primo Rinascimento: la geologia nel De re aedi icatoria di Leon Battista Alberti

The geological elements found in the De re aedificatoria by Leon Battista Alberti are discussed for the first time in detail. In Alberti we find the enlightened conception of how architectural works must be conceived to adapt to natural processes and their evolution, and not vice versa. The great architect uses, in a first place, a purelypragmatic approach to geological knowledge. Noteworthy elements are the detailed study of historical earthquakes to get an idea of ‘seismic hazard’ characterizing a specific area, a deep understanding of the evolution of river systems, the use of wells to investigate the composition of the terrains in the underground to build solidfoundation. These pragmatic elements are also accompanied by more theoretical interpretations, including very interesting reasoning about diagenesis, and on sedimentological aspects such as gradation, events of flooding and fluvial deposition, and river systems progradation due to the secular sediment supply. In his scientific interpretations, and in the new proposed vision of art, Alberti manages to reconcile in a harmonious way the innovations made by Brunelleschi, Masaccio and Donatello, fully embodying the spirit of the Florentine Renaissance, where art presupposes a profound understanding of nature and not its simple imitation in artist works.