Lagoonal Environment Research Articles

Sedimentology and geochemistry of Carboniferous-Permian marine-continental transitional shales in the eastern Ordos Basin, North China

A continuously cored well covering the Carboniferous-Permian Benxi, Taiyuan, and Shanxi formations in the eastern Ordos Basin provides a rare window into environmental conditions of the marine-continental transitional strata. Integration of petrographic, mineralogical, and high-resolution geochemical data allows marine-continental investigating the depositional environment, organic abundance, detrital influx, paleoclimate, paleo-water salinity, and paleoredox conditions of transitional facies. The marine-continental transitional strata in the Upper Carboniferous to Lower Permian consist of complex interbedding of sandstone, shale, coal and limestone. TOC contents display a considerable change in the vertical direction, with high TOC content in coal, moderate TOC in shale, low TOC content in limestone and no noticeable TOC enrichment in sandstone. The Upper Carboniferous Benxi Formation is dominated by marine facies then changing into transitional facies. The Lower Permian Taiyuan Formation is characterized by multiple alternation of marine and transitional facies. Marine limestones are characterized by low detrital influx proxies, whereas transitional shales show high detrital influx input and oxic environment. The Lower Permian Shanxi Formation is a typical marine-continental transitional depositional system, which is characterized by complex interbedding of shales, sandstones and coals. Sandy intervals were deposited in deltaic and tidal flat environment and characterized by high Ti and Al content, low TOC (0.09–0.97%, avg. 0.31%), relatively low U/Th (0.11–0.32, avg. 0.17), showing limited influence of seawater. Shale intervals were deposited in a lagoonal environment with high TOC (0.94–40.64%, avg. 5.43%), Sr/Ba and trace elemental proxies values (U/Th, 0.18–3.27%, avg. 0.44%; MoEF, 0.95–32.3, avg. 8.56; UEF, 0.67–15.17, avg. 2.53). This study shows that high-resolution geochemical characteristics of elements could be reliable indicators for sedimentary facies analysis, and hence could provide broader implications for utilizing trace element geochemistry from marine-continental transitional periods in which sedimentary environment changes frequently and organic-rich sediment accumulated under varied conditions.

Morphodynamic and sedimentary processes in salt-marshes and tidal channels of the Venice Lagoon (Italy)

Tidal landscapes are currently threatened by climate change and increasing human interferences, and are possibly subject to irreversible transformations with far-reaching social, economical, and ecological implications worldwide. The Venice Lagoon formed over the last 7500 years and represents an outstanding example of tidal landscapes where natural and anthropic processes coexist. The Venice Lagoon is a peerless laboratory to study the deposits associated with salt-marshes, tidal flats, and tidal channels under variable rates of subsidence and sediment supply. Investigations on salt marshes and tidal channels of the Venice Lagoon can provide precious insights to understand morphodynamic processes typifying microtodal lagoonal environments worldwide.

The late Oligocene xenarthran fauna of Quebrada Fiera (Mendoza, Argentina) and its implications for sloth origins and the diversity of Palaeogene cingulates

AbstractThe late Oligocene mammalian fauna of Quebrada Fiera is one of the most diverse of the Deseadan SALMA (South American Land Mammal Age). We describe its endemic xenarthran assemblage, represented by 13 species, consisting of 2 stem sloths and 11 armoured cingulates. The rare folivoran material confirms the presence of Octodontotherium, one of the early known mylodontids, and suggests the existence of a new, small, non‐megalonychid megatherioid, Similhapalops nivis. The lumbar vertebrae of Octodontotherium sp. provide the oldest evidence of xenarthry for the order. The presence at the knee joint of an ossified meniscus and cyamo‐fabella strongly suggests a plantigrade ancestral condition in Mylodontidae. Armoured xenarthrans are represented by the armadillos Eutatini (Meteutatus sp., M. lagenaformis, and Stenotatus ornatus), an undetermined Euphractinii, the ‘horned’ peltephilids Peltephilus sp. and P. undulatus, and the palaeopeltid Palaeopeltis inornatus; an undetermined Glyptodontidae, the glyptatelines Glyptatelus cf. tatusinus and Clypeotherium sp., and an undetermined propalaehoplophorine. The xenarthrans represent one‐third of the mammals of the Quebrada Fiera fauna, one of the most varied at the end of the Palaeogene in South America. This vertebrate fauna is represented by a mix of endemic taxa and other species of high latitude (Patagonian) origin, but few from low latitude faunas. A detailed study of this mammalian assemblage, complemented by detailed geological and petrographical studies, suggests the existence of strong volcanic activity, and the presence of braided rivers and lagoonal environments in open habitats under a temperate or hot climate, with savannas and/or grasslands and isolated forests during the late Oligocene at the foot of the proto‐Andes.

Intra‐ice and intra‐sediment cryopeg brine occurrence in permafrost near Utqiaġvik (Barrow)

AbstractCryopeg is a layer within permafrost containing a significant amount of cryotic unfrozen water due to dissolved salts. To explore the origin and development of cryopeg and associated brines found near Utqiaġvik, we sampled extensively within the Barrow Permafrost Tunnel. We found two types of cryopeg brines based on their distinctive locations: (a) intra‐ice brine (IiB), entirely bounded by massive ground ice, and not previously observed in the Northern Hemisphere; and (b) intra‐sediment brine (IsB), found as expected in unfrozen sediments within permafrost. The encountered IiBs were situated in small ellipsoidal or more complex shaped pockets within the massive ice at roughly atmospheric pressure. Radiocarbon dating suggests that the IiB segregated from IsB‐bearing cryopeg beneath the massive ice at about 11 ka BP, at the earliest. From geochemical analyses, IsB lenses were interpreted as having developed through repeated evaporation and cryoconcentration of seawater in a lagoonal environment, then isolated when the surrounding sediment froze and became covered by an upper sediment unit around 40 ka BP or earlier. The discovery of IiB and development of origin scenarios for both brine types validate the importance of high‐resolution sampling as enabled by the unique facility of a permafrost tunnel.

Behaviour of Metal(loid)s at the Sediment-Water Interface in an Aquaculture Lagoon Environment (Grado Lagoon, Northern Adriatic Sea, Italy)

The cycling of metal(loid)s at the sediment–water interface (SWI) was evaluated at two selected sites (VN1 and VN3) in an active fish farm in the Grado Lagoon (Northern Adriatic, Italy). In situ experiments using a transparent benthic chamber and the collection of short sediment cores were performed, to investigate the behavior of metal(loid)s in the solid (sediments) and dissolved (porewaters) phases. Total and labile concentration of metal(loid)s were also determined in sediments, to quantify their potential mobility. Comparable total concentrations were found at both sites, excluding As, Mn, Pb and V, which were higher at VN3. Metal(loid) porewater profiles showed a diagenetic sequence and a close dependence with redox (suboxic/anoxic) conditions in the surface sediments. Positive diffusive fluxes along with benthic fluxes, particularly at the more oxic site, VN1, were found for almost all metal(loid)s, indicating their tendency to migrate towards the overlying water column. Despite sediments at two sites exhibiting high total metal(loid) concentrations and moderate effluxes at the SWI, the results suggest that they are hardly remobilized from the sediments. Recycling of metal(loid)s from the SWI would not constitute a threat for the aquatic trophic chain in the fish farm.

L’ichthyofaune messinienne du bassin de Sorbas (Almería, Espagne) et ses rapports avec l’environnement sédimentaire

Fish skeletons were collected at three different levels in the Messinian of the Sorbas basin (Andalusia, South Spain). The richest fossiliferous level is a diatomitic stratum which occurs a few metres below the bottom of the evaporitic sequence. It has mainly yielded many juvenile Myctophids: Myctophum licatae and less abundant Maurolicus muelleri This indicates the occurrence of a rather deep open sea in the vicinity. Additionally, some skeletal remains of Sardina ? crassa were found in a clayey intercalation between two massive beds of gypsum. The occurrence of this marine species is indicative of the persistence of the sea during the evaporitic episode. Finally, as shown by the occurrence of aphanius crassicaudus in the postevaporitic Messinian, a lagoonal environment existed in this basin, as a result of a relative lowering of the sea level. Additionally, another fossiliferous locality yielding the same species is reported near Gafares, in the postevaporitic Messinian of the northern part of the Níjar-Carboneras basin.

Late Holocene lagoon succession and its response to environmental variations at Yongle atoll, Xisha Islands, South China Sea

Tropical coral reef lagoons that are characterized by high deposition rates are potentially useful for high‐resolution palaeoenvironmental reconstructions. We present the geochemical and accelerator mass spectrometry (AMS) 14C‐dating data of a 113‐cm gravity core obtained from the Yongle atoll lagoon in the South China Sea. The core record preserves a continuous 1,500‐year depositional history of the back‐reef lagoon environment, with sedimentation rates varying from 0.55 to 1.55 mm yr−1 (mean of 0.74 mm yr−1). Calcium carbonate (CaCO3) production was calculated based on the sediment accumulation rates and sediment density to be 807 g m−2 yr−1. The geochemical records of the studied core displayed a progressively increasing trend of storms over the past 1,500 years. The stable carbon and oxygen isotopes of the lagoon sediment have the potential to record monsoon intensity. The lagoon system of the Yongle atoll appears to have been influenced by minor terrestrial input from 1,500 calendar years before present (cal yr BP) to 500 cal yr BP, and by a strong anthropogenic influence over the past 200 years.

Origin of solutes in a regional multi-layered sedimentary aquifer system (a case study from the Rub’ al Khali basin, Saudi Arabia)

An isotope and solute evaluation was applied to identify the origin and mechanisms of groundwater salinization in three major Tertiary aquifers in the Rub’ al Khali topographic basin. We demonstrate that the groundwater chemistry evolved from a low- (1800 ppm) to high- (>120,000 ppm) salinity Na–Cl water type, regardless of the aquifer. The similarity in water types between the groundwater from the different formations suggests that the same origin and geochemical processes may be controlling the salinity and major ion chemistry in these aquifers. The suite of hydrogeological, hydrochemical (Cl vs. Br), and isotopic (Cl vs δ18O and Br vs δ81Br) data indicates that the source of solutes is associated with the entrapment of evaporated paleo-seawater (connate water) in nearshore and lagoonal environments during the time of deposition. Moreover, the results from the 87Sr/86Sr ratios show no evidence of significant vertical connectivity between the three Tertiary aquifers. Instead, the data support that evaporated paleo-seawater was trapped in each aquifer individually during the time of deposition, and that each has evolved similarly through water-rock and redox reactions. The stable isotopic compositions of δ18O, δ2H, and 14C show that the entrapped paleo-seawater was partially flushed out by fresh meteoric water during the Late Pleistocene and Early Holocene periods.

For an Effective and Sustainable Management of Non-Tydal Lagoon Environments to Counteract the Eutrophication Effects

Coastal lagoon environmental picture with the tendency to accumulate organic detritus, structural eutrophication, risks of dystrophy, with loss of biodiversity and fish products, is briefly described. Mitigation solutions are analyzed, focusing on the removal of macroalgal masses, artificial water renewal, sediment oxidation and more, highlighting the limits and benefits of each solution. With regard to the sediment oxidation, on which more emphasis is placed here, a review of the results obtained on two Tyrrhenian lagoons is made, through field experiences conducted between 2005 and 2021. These results showed an overall mitigation of the eutrophication effects, with reduction of nutrient load and sediment labile organic matter, reduction of macroalgal development, phanerogam return and increase in zoobenthonic biodiversity. Some possible effects of sediment resuspension on contaminants are reported.

New Dinosaur Tracks from the Lower Barremian of Portugal (Areia do Mastro Formation, Cape Espichel)

We present a new tracksite with multiple dinosaur tracks from the lowermost Barremian (Lower Cretaceous) of the Cape Espichel (Sesimbra, Portugal). The tracks are localized on three beds on the top carbonate beds of the Areia do Mastro Formation. Those bioclastic, nodular limestones were deposited in a very shallow subtidal-intertidal, restricted lagoon environment. The track surfaces are very dinoturbated, with a substantial number of tracks. Several tracks assign to sauropods, ornithopods and theropods dinosaurs were recorded. Due to heavy bioturbation and the preservation conditions, it is not possible to define trackways; some preliminary work done on the tracks could disclose some behaviours of their producers. Several species of carnivore and herbivore dinosaurs crossed that large area at different times. Herbivores may have used the lagoon margin as passage between feeding spots, while carnivores frequented the area to hunt in groups or individually.

A diatom-based Holocene record of sedimentary and oceanographic environmental changes within the Beibu Gulf, NW South China Sea

A sediment core from a nearshore setting (10.8 m in water depth) of the inner Beibu Gulf, northwestern South China Sea, was analyzed in terms of diatom assemblage composition, grain size distribution and radiocarbon dating, with aim to describe sedimentary and oceanographic environmental changes during the Holocene. The fossil diatom record and changes in granulometry reveal that sea-level fluctuations had a strong influence on the evolution of hydrographic system, which changed significantly with rapid sea-level rise in the early Holocene ca. 10,000–7800 cal. yr. BP. These fluctuations continued in a series of stages dated to the middle Holocene ca. 7800–6200 cal. yr. BP, with sea-level increase, followed by a prolonged sea-level retreat during ca. 6200 to 3300 cal. yr. BP, and finally a relatively high sea level from ca. 3300 cal. yr. BP to the present. The resultant sedimentary facies could be divided into seven stages inferred by the diatom distribution and grain size characteristics: a river channel/beach environment at ca. 10000–9500 cal. yr. BP, a lagoonal environment at ca. 9500–7800 cal. yr. BP, a relatively broad embayment at ca. 7800–6200 cal. yr. BP, a bay at ca. 6200–3300 cal. yr. BP and a coastal environment setting up to present day. The coastal environmental setting has been subject to some shifts in climate and sea-level beginning with strong terrestrial influx at ca. 3300–1400 cal. yr. BP, which was then replaced by strong hydrological circulation at ca. 1400–800 cal. yr. BP, and a relative stable sedimentary environment approximate to the coast from ca. 800 cal. yr. BP to present.A very obvious increase in diatom abundance in the early and late Holocene reflected terrestrial influx transporting nutrients, driven by precipitation changes influenced by the Asian monsoon circulation pattern, particularly in the early Holocene. Increased anthropogenic impact, i.e. an enhanced nutrient condition, was inferred from higher abundances and reasonably high diatom diversity in this local record from 1400 cal. yr. BP, especially in the last 800 years. Rapid shifts in the diatom composition and grain size distribution at about 1400 and 1000 cal. yr. BP were observed that could be interpreted as overlapping influences of a global scale paleo-climate anomaly and local human activities. This study demonstrates the effectiveness of using diatom for understanding regional paleoenvironment change driven by both global climate changes and anthropogenic impact in coastal area of the Beibu Gulf, northwestern South China Sea.

Evaluation of Environmental Quality of Mediterranean Coastal Lagoons Using Persistent Organic Pollutants and Metals in Thick-Lipped Grey Mullet

The evaluation of past and present anthropogenic impacts affecting the ecological quality status of transitional ecosystems is crucial from the perspective of protecting them from further deterioration, and to evaluate remediation and restoration measures. Contamination patterns of thick-lipped grey mullet from two Mediterranean coastal lagoons within a protected area in Italy were assessed and compared in order to evaluate their overall quality status and to collect information that can provide useful feedback on management choices aimed at enhancing environmental quality and biodiversity conservation. The quality status of the two lagoons was evaluated by an environmental assessment methodology based on indicators of direct and indirect human pressures, while a broad range of analyses were carried out to determine the presence and concentration of persistent organic pollutants (POPs) and metals in fish muscle tissue. A good quality status resulted for both lagoons, and an overall limited anthropogenic impact in the surrounding area. This could account for POPs and metal contamination levels found in mullet, although limited, and relating to their patterns. The overlap of results achieved with the two evaluation approaches can provide support for management choices in Mediterranean lagoon environments, especially for those committed to the protection and conservation of biodiversity.

Tide-dominated deltas responding to high-frequency sea-level changes, Pre-Messinian Rifian Corridor, Morocco

ABSTRACTThe Rifian Corridor was an ancient sea strait that connected the Mediterranean Sea with the Atlantic Ocean during the Miocene. Key outcrop exposures of this corridor's sedimentary fill are exposed at the Ben Allou, El Adergha, and Driouate localities, in the Fez–Meknes region, Morocco. These display cyclic successions that formed immediately before the disappearance of the Rifian Corridor, and the associated isolation and desiccation of the Mediterranean Sea. Sedimentary cycles at Ben Allou consist of: facies 1, Organic-matter-bearing blue claystones; facies 2, gray marlstones intercalated with turbidites; and facies 3, yellow-brown, coarse-grained calcarenites. Based on their coarse grain size, presence of reactivation surfaces, bidirectional current structures, and mud drapes as well as microfossil, macrofossil and trace fossil assemblages, we interpret the calcarenites (facies 3) as prograding, strait-adjacent tide-dominated deltas transitioning from large subtidal compound dunes to intertidal sand sheets that are composed mostly of authigenic carbonate sediment. The two fine-grained facies were deposited in deeper prodelta (facies 2) and shelfal (facies 1) environments, as shown by our combined sedimentological and paleontological evidence. Cross-sectional channel geometries provide a means for reconstructing the delta's paleo–tidal range, suggesting that it was macrotidal, and likely amplified by the paleogeometry of the Southern Rifian Corridor, to at least 4.2 m. The cyclic succession of corridor fill exposed here likely is the result of three, roughly 70 m fluctuations of eustatic rise and subsequent fall, possibly linked to ∼ 100,000-year glacial–interglacial climate fluctuations. Broadly similar, contemporaneous sedimentary successions from the outcrop at El Adergha, 40 km east of Ben Allou, show that these sea-level variations affected a wide range of the Corridor, while rocks at the locality of Driouate, 9 km south of Ben Allou, show evidence for lagoonal environments on the landward side of the corridor, which were subject to periodic marine regressions and floodings. These results are reinterpretations of previous work on these sediments, with implications for depositional processes in the Rifian Corridor, Miocene paleoclimate, and the Messinian salinity crisis.

Palaeontological and sedimentological characteristics of the Changhsingian (Late Permian) platform−margin sponge reef and intraplatform skeletal mound in NE Sichuan Basin, South China: their palaeoenvironmental implications

Well-preserved fossil reef/mound-building communities and shallow microfacies have been recovered from Changhsingian platform−margin sponge reef at the Panlongdong Section and intraplatform sponge skeletal mound at the Yanggudong Section in NE Sichuan Basin, South China. The present contribution focuses on the palaeoenvironmental implication of the differentiated development processes on the platform−margin reef and intraplatform skeletal mound based on the palaeontology and sedimentology. Precise field assessments and macroscopic/microscopic qualitative observations led to the identification of five reef/mound-building community and 14 reef/mound-related microfacies in the 2 sections of Changxing Formation. In the Panlongdong platform−margin sponge reef, reef-building communities are recognized into Amblysiphonella Community, Preperonidella−Amblysiphonella Community, and Preperonidella–Sollasia Community in ascending order. The reef-related microfacies are mainly classified into calcisphere−pelletoid wackestone to packstone, crinoidal wackestone to packstone of shallow water bank environment, hypercalcified sponge bafflestone, calcareous algae−hypercalcified sponge binding framestone, hypercalcifed sponge−calcareous algae bindstone, and calcareous algae−hypercalcifed sponge rudstone of reef environment, and benthic foraminifera−calcareous algae wackestone to packstone of shallower water lagoon environment. Two mound-building communities can only be found in the Yanggudong intraplatform skeletal mound, including Preperonidella−Intrasporeocoelia Community of lower part and Preperonidella−Sollasia Community of upper part. The mound-related microfacies include calcisphere−calcareous algae wackestone to packstone, crinoidal wackestone to packstone and crinoidal packstone to grainstone of shallow water bank environment, hypercalcified sponge bafflestone and cyanobacteria−hypercalcified sponge binding bafflestone of skeletal mound environment, benthic foraminifera−calcareous algae packstone grainstone of shallower water bank environment and benthic foraminifera−calcareous algae wackestone to packstone of shallower water lagoon environment. These palaeontological and sedimentological analysis results have facilitated the classification of sponge reef and skeletal mound sections corresponding to a solitary shallow benthic zone into multiple microfacies attributed to variable environmental depositional conditions. The differentiated evolutional process of multiple reef/mound-building stages at the Panlongdong and Yanggudong sections clearly demonstrate a general shallowing-upward trend from an inner shelf setting to a supratidal and low energy lagoon environment.

Facies characterization and depositional environment of Baluti Formation (Late Triassic) from selected sections in the Kurdistan region, Northern Iraq

Facies analysis and depositional environment of Baluti Formation (Late Triassic) were studied from the Galley Derash section in the High Folded Zone and Sararu section in Northern Thrust Zone, from Duhok area, Kurdistan region, Northern Iraq. Lithologically, the Galley Derash section comprises 73 m brecciated dolomitic marly limestone, bedded dolomitic limestone, and brecciated sandy limestone which all interbedded with dark gray shale, while in Sararu section, it comprises 90 m of sandy dolomitic limestone interbedded with gray shale and brecciated marly limestone. Depending on field observations and petrographic analysis, three different litho units were recognized in the Baluti Formation in Galley Derash section and the same numbers of litho units were recognized in Sararu section with slight difference in lithology comparing to the Galley Derash. The petrographic study of the formation is based on 32 thin sections which showed that the majority of carbonates are carbonate mud (micrite) with less sparite. The skeletal grains include benthic foraminifera, dasycladacean algae, calcareous red algae, ostracods, brachiopods, bivalves, calcispheres, echinoderms, gastropods, ammonoids, and bioclasts. Non-skeletal grains involve peloids, extraclasts, intraclasts, and ooids. Based on detailed microfacies analysis of carbonate and field description, nineteen lithofacies types are distinguished in both studied sections of Baluti Formation. These facies were grouped relating to their environmental interpretation, into three basic types of facies associations: back shoal/lagoon, shoal, and foreshoal/slope. The field observation and petrographic, facies, and textural analysis indicate that Baluti Formation was deposited in the lower part of the lagoonal environment which changed into shoal and foreshoal/slope toward the upper part in the Galley Derash section, whereas in Sararu section, it was deposited under back shoal/lagoonal conditions including repeated intervals of shoal environment which changed into foreshoal/slope in the upper part.

Morphological changes of the large foraminiferal genus Loftusia during the Maastrichtian and its palaeogeographical inferences from the Zagros and Neotethys basins

This study examines the morphological changes of the Loftusia genus from the Zagros Belt of southern Iran using quantitative data. Eight Tarbur Formation outcrops were investigated in the High Zagros and the Lurestan sub zones. The observed Loftusia species are of mid Maastrichtian age in the High Zagros and the mid to late Maastrichtian age in the Lurestan and Murak areas, and they are often observed in deposits of the lagoon environments with high nutrient conditions. Two (Tang-e Shabi Khoon area) and four (Murak area) cycles were recognized based on the morphological parameter changes of Loftusia species. The correlation of the number of cycles of Loftusia species between the Zagros basin and the different areas of the Neotethys basin indicates that Loftusia species sizes change in time. The obtained data shows that the number of the sedimentary cycles (alternating shale and limestone layers) in the High Zagros zone is more different than the Lurestan zone. The High Zagros zone comprises rich terrigenous shale with higher nutrient flux in comparision to the Lurestan zone and other areas of the Neotethys basins. The number of cycles decreased from the southeast toward the northwest of the Neotethys basin. It is thought changes in Loftusia species in the Zagros basin are related to nutrient input during the Maastrichtian age and were independent of evolutionary trends.The genus Loftusia disappeared in the High Zagros zone at the end of the late Maastrichtian. The subsidence of the basin is associated with the Dena and High Zagros Faults. Due to the activities of those faults, the Tabur Formation was not deposited in the High Zagros zone areas. The genus Loftusia appeared in the southeast region of the Arabian plate during the early Maastrichtian, and migrated to the northwest of the Neotethys during the Maastrichtian.

Late Quaternary landscape evolution of the buried incised valley of Concordia Sagittaria (Tagliamento River, NE Italy): A reconstruction of incision and transgression

While recent landscape changes can be usually easily read through accessible morphological features, relatively ancient processes can be difficult to detect as the associated morphologies and deposits are often buried below younger sediments. With the aim of understanding the evolution of the distal Venetian-Friulian Plain (NE Italy) after the Last Glacial Maximum (LGM), this work presents the analysis performed on a dataset of ca. 2300 mechanical and hand-made cores, which allowed a detailed reconstruction of the formation and evolution of an incised valley, now almost completely filled and with little to absent morphologic expression. Such valley, up to 1.2 km wide, with a depth of 20 m below the LGM alluvial plain and traced for a length of 25 km, is the result of the complex interplay between minor spring-fed rivers and the Tagliamento River. The detailed characterization of the infilling allowed to identify two main phases in the valley evolution. The first one is related to the activity of the paleo Tagliamento River and led to the deposition of a 10 m thick gravelly unit (ca. 19–9.5 ka cal BP). The second phase, which followed a disconnection of the Tagliamento, is linked to the Holocene marine transgression and led to the formation of a lagoon environment within the valley and to the deposition of a ca. 15 m thick unit of lagoon muds (ca. 8 ka cal BP - historic time). This latter unit lays on top of gyttja deposits, indicating for the first time in this area the presence of widespread lacustrine environments in the Early Holocene. This work presents an in-depth analysis on the evolution of a distal plain incised valley, from its formation to its final filling, providing at the same time the means to describe the development of the entire alluvial plain landscape, spanning from the end of the LGM to the middle Holocene. We present new data on the paleoenvironmental and morphologic evolution of the Venetian-Friulian Plain area as a consequence of the interplay between autogenic forces and sea-level rise. Our study allowed to understand the importance of both Alpine rivers and groundwater-fed streams in the formation of large incised valleys in the coastal sector of the whole Venetian-Friulian Plain. Finally, as during the transgressive phase the upstream sediment input in the valley was almost absent, this study provides insights into facies and architecture of a rare example of downstream-controlled filling of an incised valley.

Biotic response to the latest Cenomanian drowning and OAE2: A case study from the Eastern Desert of Egypt

The changes in macrofauna and microfauna, before, during and after the latest Cenomanian global Oceanic Anoxic Event (OAE2), from the Eastern Desert of Egypt are documented, along with an inferred paleoenvironment. The age of the studied OAE2 interval is constrained by the last occurrence of the marker calcareous nannofossils species Axopodorhabdus albianus along with the previously identified positive δ13C excursion from the coeval ammonite Vascoceras cauvini Zone (= Neocardioceras juddii Zone), enabling correlation with the peak ‘b’ of the OAE2. Based on the studied microfaunal assemblages, a warm shallow restricted lagoonal environment with mesotrophic conditions and strong seasonality is inferred. The presence of a rare ammonite (and ostracods) attest to the intermittent introduction of marine waters within this inner ramp setting. In terms of sequence stratigraphy, two 3rd order depositional sequences are recorded. The top surface of the first depositional sequence, at the sequence boundary, SB Ce 5 (the start of the OAE2), is marked by an abrupt faunal change with reduced abundances of the macrofaunal elements. This is in tune with other Egyptian records of relatively smaller loss (10 %) at the Cenomanian-Turonian boundary, as compared to much higher numbers (53–79% of species), globally. This faunal (biotic bottleneck) and lithological change (from siliciclastic-dominated deposits to a largely carbonate-dominated one) at the SB Ce 5 is attributed as a response to the latest Cenomanian drowning (the highest sea-level during the Phanerozoic), that also resulted in the formation of carbonate platform.

Assessing the Relationship of LST, NDVI and EVI with Land Cover Changes in the Lagos Lagoon Environment

AbstractThe Lagos Lagoon is under increased pressure from growth in human population, growing demands for natural resources, human activities, and socioeconomic factors. The degree of these activities and the impacts are directly proportional to urban expansion and growth. In the light of this situation, the objectives of this study were: (i) to estimate through satellite imagery analysis the extent of changes in the Lagos Lagoon environment for the periods 1984, 2002, 2013 and 2019 using Landsat-derived data on land cover, Land Surface Temperature (LST), Normalised Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI); and (ii) to evaluate the relationship between the derived data and determine their relative influence on the lagoon environment. The derived data were subjected to descriptive statistics, and relationships were explored using Pearson's correlation and regression analysis. The effect of land cover on LST was measured using the Contribution Index and a trend analysis was carried out. From the results, the mean LSTs for the four years were 22.68°C (1984), 24.34°C (2002), 26.46°C (2013) and 28.40°C (2019). Generally, the mean LSTs is in opposite trend with the mean NDVIs and EVIs as associated with their dominant land cover type. The strongest positive correlations were observed between NDVI and EVI while NDVI had the closest fit with LST in the regression. Built-up areas have the highest contributions to LST while vegetation had a cooling influence. The depletion in vegetative cover has compromised the biodiversity of this environment and efforts are required to reverse this trend.

The evolution of a coastal wedge in response to Plio-Pleistocene climate change: The Northern Adriatic case

This work reconstructs the complex evolution of a coastal wedge in response to Pliocene tectonic activity and Pleistocene climate change recorded in the upper Neogene subsurface succession of the Friulian-Venetian Basin (FVB), since the latest Messinian sea-level drop event to the late Pleistocene. The FVB is the north-eastern portion of the wider Po Plain-Adriatic foreland basin (Northern Italy), which bounds to the east the whole Italian peninsula and is the place where most of the Italian hydrocarbon offshore fields presently occur. Also, the city of Venice and its surrounding lagoon is presently one of the sites most sensitive to land subsidence worldwide and even a few mm loss of ground elevations can significantly change the natural lagoon environments and threaten the city's survival. To this purpose, we have integrated seismics and well logs analysis with 1D-geohistory modelling on wells, using corrected paleobathymetric data, in order to extract decompacted sedimentation rates. The new age model is based on a complete chronostratigraphic revision of the continuously cored Venezia 1 well, correlated with other 12 hydrocarbon wells to form proper geological depth-calibrated profiles across the basin. Results suggest a major tectonic control on marine sedimentation and basin accommodation space changes during the entire Pliocene-early Pleistocene time, influenced by the Northern Apennines thrust fronts migration. On the contrary, the mid-upper Pleistocene deposition, characterized by a weak deformation, is mainly controlled by climate and basin geometry. During the early mid Pleistocene, an impressive progradational cycle (in the literature usually named “Sabbie di Asti group”) followed the deposition of deep-water turbidites; in this work, we subdivide the different clastic bodies the formation is made of. The uppermost part of the “Sabbie di Asti group” is dominated by shallow-water to continental deposits showing a prominent regressive-transgressive cyclicity, where unfortunately chronological ties are limited. Nevertheless, 6 main cycles driven by 100 kyr Milankovitch-type ciclicity were laterally correlated by means of the well electric logs and linked to marine ∂18O isotope and eustatic curves.