Marl Deposits Research Articles

Description of the Late Holocene South‐east Saline Everglades, Florida palustrine depositional environment with comparisons to other Holocene environments

AbstractA transgressive palustrine depositional model is described for the South‐east Saline Everglades, Florida. The origin, development and termination of freshwater carbonate mud (marl) deposition along the very low gradient Late Pleistocene carbonate ramp are responses to changing rates of rising sea level during the Late Holocene. The onset of the Late Holocene is defined by a decrease in the rate of sea‐level rise from between 2 and 3 to <1 mm year−1. Freshwater marl deposition began with this decrease ca 3165 ± 187 year BP, in a shallow (<0.3 m deep), ephemeral wetland that developed landward of a fringing mangrove forest and is maintained by seasonal Everglades water delivery. Sedimentation kept pace with sea‐level rise forming a 1.2 m thick wedge shaped, landward thinning deposit. The rate of global sea‐level rise began to accelerate ca 1900, the Anthropocene Marine Transgression, and presently the regional rate is 9.4 mm year−1. Saltwater encroachment rates >80 m year−1 are driven by sea‐level rise. Saltwater encroachment resulted in retreat and transformation of coastal communities and their biogenic facies, resulting in a decrease in freshwater wetlands and marl production. Inundation ponding, mangrove overstep and the beginning of submergence are the responses to the accelerating rate of sea‐level rise, however, small scale topographic and tidal ingress differences create considerable variability between Biscayne Bay and Florida Bay coastal basins. The freshwater marl producing habitat will probably be lost within 55 years, and submergence within the next century at the present rate of sea‐level rise. The unique South‐east Saline Everglades depositional environment is compared to other Holocene palustrine depositional environments.

Development and chronology of the Late Jurassic shallow-water carbonate deposits of the Holy Cross Mountains area, central Poland

The Late Jurassic shallow-water carbonates with intervening clayey-marly deeper-water deposits in the Holy Cross Mts. area formed over large bank of the elevated part of the Northern Tethyan Shelf during about 12 myr. They comprise three main successions (I, II and III) deposited partly in different environmental conditions, controlled by tectonic and climatic factors, and still preserved in the north-eastern margin, the north-western margin and the south-western margin of the Holy Cross Mountains. The history of sedimentation is presented according to the concept of the large tectono-stratigraphic units COK, LUK and KVB, which owe their origin to variable rates of tectonic subsidence, as introduced by Kutek (1994) for the area of central Poland. The studied deposits of the COK megasequence corresponding to the Upper Oxfordian and the Lower Kimmeridgian up to the Hypselocyclum Zone consist of coral limestones, various grained (including oolitic) limestones, and micritic limestones formed over the gradually enlarging shallow-water carbonate platform of the Holy Cross Mts. This platform was subsequently subdivided into two elevated areas, separated by a depressed zone in the middle, bounded by the Nowe Miasto–Iłża–Bałtów Fault Zone in the north-east and the Holy Cross Fault System in the south. The younger megasequence LUK with it strongly transgressive character marks the successive stages of the marine transgression which entered the central, lowered part of the area of the Holy Cross Mts. from the west, where it appeared already in the early Hypselocyclum Chron. It successively spread across the Holy Cross Mts. area towards the north-east and south bringing everywhere the deposition of various oyster lumachelles and marls with ammonites at the end of the Hypselocyclum Chron and during the Divisum Chron of the Early Kimmeridgian to the Acanthicum/Mutabilis Chron of the earliest Late Kimmeridgian. The following megasequence KVB is represented by the detrital lumachelles and chalky limestones with nereineids of the Eudoxus Chron of the Late Kimmeridgian marking the development of still younger shallow-water carbonate platform in the uplifted areas in the north-eastern and possibly the south-western margins of the mountains, allegedly subdivided by a deeper area of sedimentation of marly deposits. The youngest Late Jurassic deposits of the Holy Cross Mts., are very fragmentarily preserved, mostly because of Early Cretaceous uplift and erosion. They suggest an initial episode of complete drowning of the carbonate platform which became covered by marly deposits during the Early Tithonian, and the subsequent restoration of shallow-water carbonate sedimentation at the end of the Early Tithonian.

Albian sedimentation in western Atlas, Morocco

Detailed study of field sections and extensive ammonite collection allowed to specify the sedimentary evolution and age of the Albian series of the Western Atlas (Morocco). After a significant hiatus of earliest Albian age, the Albian transgression began in the late Douvilleiceras leightonense Zone with partly clastic deposits. A transgressive pulse gave way to clayey marl deposits (Douvilleiceras mammillatum Zone), which evolved upward to partly carbonate, laminated deposits of late early Albian to earliest middle Albian age (Lyelliceras pseudolyelli to early Lyelliceras lyelli zones). A major hiatus that encompassed most of the middle Albian, was followed by a new transgression marked first by sandy deposits (Dipoloceras cristatum and Pervinquiria pricei zones), and then by clayey marl and limestone nodules (Pervinquieria inflata Zone). A sharp sea level fall (late Pervinquieria inflata to early Pervinquieria fallax zones) led to the development of a shallow marine carbonate shelf (Kechoula Formation). A last transgressive pulse allowed deposition of outer shelf clayey marls (Pervinquieria rostrata to Arrhaphoceras briacensis (?) zones), interrupted near the Albian-Cenomanian boundary by a sea level fall and hiatus. Anoxic to disoxic conditions are recorded in the latest early Albian and the late Albian, which correlate with the Leenhardt and Breistroffer levels, respectively. Correlations with Albian successions in North Africa and southern Europe suggest a mainly eustatic origin for the most important sedimentary discontinuities, although the late Albian sea-level drop may be tectonically enhanced.

Geological features of the Zn-Pb prospect in the Bou-Izourane district (Morocco)

The Zn-Pb mineralization in the Bou-Izourane district, located in the High Atlas Mountains of Morocco, contains estimated reserves of 40 200 tons of ore with an average grade of 20% Zn and 3.5% Pb. It is developed on N–S to NNW–SSE-trending faults that cut Liassic carbonate marl deposits. The paragenetic mineral sequence consists of galena, sphalerite and late-stage calcite. Oxidation phases of galena into cerussite and sphalerite into smithsonite are common in the Bou-Izourane ore, linked to the infiltration of meteoric waters and the oxidation of these sulphides. The Zn-Pb mineralization runs parallel to the fluorite veins associated with the igneous rocks of Tamazeght, but no petrographic or field relationship has been demonstrated between these two mineralizations (i.e., Zn-Pb and fluorite). The distribution of rare earth elements and yttrium (REY) in the Zn-Pb mineralization of Bou-Izourane shows a notable similarity with the Mississippi Valley Type (MVT) mineralization of the Central High Atlas of Morocco, although the concentrations more closely resemble those of REY in fluorite linked to the magmatic-hydrothermal activity of Tamazeght. However, the analysis of their distribution in post-fluorite calcite and post-Zn-Pb calcite reveals a strong concordance, suggesting that these two calcites are associated with the same phase and have a common origin. The classification of the Zn-Pb prospect in Bou-Izourane remains controversial, fluctuating between an MVT-type mineralization, similar to most Zn-Pb mineralizations in the Central High Atlas of Morocco, and a mineralization linked to the magmatic-hydrothermal activity of Tamazeght, which could provide heat and metallogenic material. Characterizing the Zn-Pb ore of Bou-Izourane is crucial for the future exploration of zinc and lead deposits in the High Atlas of Morocco and could advance the development of Zn-Pb mining in the region, from artisanal exploitation to professional mining

Black Soils in the Eastern Mediterranean: Genesis and Properties

This study investigates the distribution, morphology, and properties of these soils, focusing on areas such as littoral plains, high hilly areas, and rift depression valleys. Black soils occur in the eastern Mediterranean with a limited distribution, and some of them meet the requirements for black soils according to the INBS (International Network of Black Soils), while others do not. Black soils can be categorized into three types based on their genesis and evolution: calcareous black soils (mainly raw rocky rendzina), hydromorphic black soils, and black soil on basalt. While black soils were found in various bioclimatic stages and parent materials, their presence was notably limited in certain areas, contrary to prior indications. A soil morphology analysis revealed distinct color variations and depths, influenced by the accumulation of organic matter for hydromorphic and calcareous black soils and basaltic parent material for black soils on basalt. A particle size analysis indicated texture variations from clay to loam, with no clear indication of illuviation. A chemical analysis showed alkaline pH levels, except in basalt-derived soils, which exhibited a slight acidity. Hydromorphic black soil is the most important in terms of expansion and agricultural use and is only found in limestone marl deposits and lakes in depressions emerging from Dead Sea rifts under conditions of saturation or poor drainage. These soils have a thick, dark moly horizon and a high organic matter content.

Use of Electrical Resistivity Tomography for Joint Geophysical and Geotechnical Landslide Characterization: A Case Study

Abstract Slope movement processes include complex soil and rock failure mechanisms. Their study benefits from a multidisciplinary approach based on a wide range of information including geological and geomorphological mapping, and geotechnical and geophysical investigations. This research paper focuses on the characterization of the Tamentout landslide that occurs in the southeast of Jijel province. The study area belongs to the Tellian domain in which the geological outcrops are dominated by Senonian formations, composed of marl deposits overlain by Numidian flysch of Aquitano-Burdigalian age, with a sloping topography ranging from 20° to 30°. The geophysical approach consists of processing the available geophysical data of resistivity, obtained by the Electrical Resistivity Tomography (ERT). This study aims to characterize the internal structure, and the changes in water saturation within the unstable mass and locate the depth of slip surface associated with this landslide. Through this work, we combined geological and geotechnical investigations with electrical resistivity tomography (ERT). This combination gave a more detailed image of the substrate geology and structure of the landslide zone. The 2D resistivity results show that the basement consists of two main formations. The first one is a highly conductive formation with a resistivity range between 2 and 25 Ωm, a depth of 0-8 m, and is interpreted as a saturated marl-clay overlaying. The second, a hard and compact formation with a resistivity range between 50 and 200 Ωm and a depth range of 8 to 40 m, was interpreted as a substrate of tellian marls. The presence of boulders of Numidian sandstone within the two formations is materialized by a very high resistivity value ranging from 500 to 1000 Ωm. The slip surface was located on the layer with low resistivity (2-25 Ωm). The precise determination of the depth of the shear zone is of vital use in implementing mitigation measures and carrying out the stabilization work of this unstable zone. Through this work, we will highlight the advantage of the combination of available results of the geological, geotechnical investigations and electrical resistivity tomography (ERT) carried out in the study area.

SIMPLE STRUCTURES AND COMPLEX STORIES: POTENTIAL MICROBIALLY INDUCED SEDIMENTARY STRUCTURES IN THE EDIACARAN SERRA DE SANTA HELENA FORMATION, BAMBUÍ GROUP, EASTERN BRAZIL

ABSTRACT Microbially induced sedimentary structures (MISS) are abundant in Ediacaran and lower Cambrian successions. However, the relationship between MISS distribution and facies has not been thoroughly explored in Ediacaran–Cambrian successions in South America. This study documents the occurrence of MISS and other potential biogenic structures from the late Ediacaran Serra de Santa Helena Formation in the Bambuí Group of eastern Brazil. This unit overlies the Cloudina-bearing Sete Lagoas Formation and is a mixed carbonate-siliciclastic succession devoid of macroscopic body fossils. Potential microbial structures include wrinkled structures such as “elephant-skin” and Kinneyia-like textures, as well as pustular structures and abundant positive epirelief discoidal structures. Another putative biogenic structure is a mm-wide meandering groove resembling a simple locomotion trail of a small vagile benthic metazoan. Microbial surface textures (i.e., “elephant skin” and Kinneyia-type wrinkles) were mainly observed in heterolithic deposits, usually at the interface between sandstone and siltstone/shale. On the other hand, discs show a facies-independent distribution, observed in heterolithic as well as carbonate and marl deposits. Petrographic analyses of these discs suggest that they have complex origins and some of them may be diagenetic structures. Thus, while facies may have strongly controlled the preservation of MISS-related structures and textures in the Serra de Santa Helena Formation, their abundance and diversity in tidal flat deposits indicate the wide distribution of matgrounds in these shallow marine paleoenvironments. Also, we demonstrate how detailed description and classification of simple features, such as discoidal structures, is an important task for paleoenvironmental reconstruction of marine ecosystems at the Ediacaran–Cambrian transition when the microbially bounded substrates played important roles in the dynamics of coastal environments.

Ancient Ponds, Marl Deposits, and Native American Archaeology in the Ridge and Valley Province of Maryland and Pennsylvania

Ponds of early to middle Holocene age are identified in the Ridge and Valley Province of Maryland and Pennsylvania through the occurrence of marl deposits associated with the floodplains of low order streams. A 2-sigma calibrated radiocarbon date indicates that marl formation began no later than 7812–7326 BC. The ponds and associated wetlands are one focus of native settlement movements in the region. Excavations and borings into marl, marl-related sediments and adjacent deposits reveal sequences of marl, produced during periods of ponded and still water, alternating with strata of organic, alluvial silts. These profiles represent the shrinking, swelling, and periodic disappearance of ponds. Changes in stream dynamics and climate are explored as explanations for these physical changes. Archaeological data is useful for understanding the timing of these paleo environmental changes. In turn, an understanding of the nature of the pond environments enhances reconstructions of Indian settlement and subsistence strategies.

X-ray fluorescence (XRF) fingerprinting of Palaeogene deposits in Denmark

In this study, we test if cost-efficient X-ray fluorescence (XRF) analyses can be used to fingerprint Palaeogene clay and marl deposits in Denmark. A total of 67 samples from key sites in Denmark have been analysed. Our preliminary results indicate that it is possible locally within 10–30 km to distinguish between most of the Palaeogene units, but on a regional scale across Denmark, the units are not unique, and this probably reflects variations in clay mineralogy, grain size and calcareous content. Accordingly, we suggest that a comprehensive reference database is now needed if the full potential of the method is to be utilised, and this will ultimately result in more reliable geological models.

Eocene to middle Miocene contourite deposits in Cyprus: A record of Indian Gateway evolution

Bottom current deposits (contourites) form in association with modern-day or ancient oceanic gateways. A paucity of examples in the ancient record and the lack of consensus on diagnostic criteria for differentiating them from other deepwater deposits limit our understanding of how they may record past global oceanic circulation, tectonic events and gateway evolution. This work describes an exceptional example of Eocene to middle Miocene deep-marine deposits located both onshore and offshore deepwater environments around the island of Cyprus. Multidisciplinary approaches were used to discriminate contourite facies associations, propose a sedimentary model, and interpret the relations with regional tectonics and the evolution of the nearby Indian Gateway. Contourite deposits appear in late Eocene to middle Miocene intervals interstratified with pelagic/hemipelagic sediments, turbidites and mass-transport deposits (MTDs). These deepwater deposits developed along a slope basin located on the upper plate of an active margin, evolving from a wide basin formed during a period of tectonic quiescent into a series of shallowing-upward, segmented sub-basins affected by compressional stress. The present study proposes a sedimentary model in which two contourite depositional systems developed: first in the Eocene (dominated by finer-grained contourites), and then during the latest Oligocene to middle Miocene (dominated by coarser-grained contourites). Both systems were buried by extensive marl deposits and record the respective influence of deep (circulating NW) and intermediate (circulating SE) water masses. The long-term evolution of the contourites reflects tectonic events that enhanced subduction processes south of Cyprus as well as exchange between the Neotethys Ocean and the Indian and Atlantic Oceans —until the final closure of the Indian Gateway by the end of the middle Miocene, when a new circulation pattern was established with the formation of the Mediterranean Sea.

A mud-dominated coastal plain to lagoon with emerged carbonate mudbanks: The imprint of low-amplitude sea level cycles (mid-Upper Cretaceous, South Iberian Ramp)

The middle Santonian-lower Campanian carbonate-mud dominated succession deposited in the northeastern margin of the South Iberian Ramp (La Cañadilla Fm, NE Spain) shows a complex set of interfingered facies developed in a low-energy and low-gradient shallow-marine to coastal environment. Three facies belts characterize the environment reconstructed in this work: (1) a low-energy shallow marine lagoon dominated by radiolitid rudist limestones and miliolid-rich facies with variable carbonate-mud content; (2) a transitional belt with a patchy distribution of ponds and mudbanks. This belt mostly consists of miliolid-rich limestones with variable amount of fenestral porosity, which are interfingered with charophytes and gastropod marls and limestones usually mixed with miliolids; (3) a coastal plain with strong freshwater influence characterized by the sedimentation of marls and limestones with charophytes, gastropods and root traces and intraclastic/black pebble limestones. The studied succession is arranged in high-frequency sequences, including meter-scale parasequences bounded by widespread flooding surfaces, which stack in five larger-scale shallowing-upward sequences (6–20 m thick). The time calibration of these sequences obtained from strontium isotopes and biostratigraphic data (benthic foraminifera) suggests a major control in the sedimentation by climate-driven low-amplitude sea level oscillations formed in tune with the long- and short-eccentricity orbital cycles. Cyclic sea level rises controlled the existence of widespread flooding events in the low-gradient carbonate ramp at the onset of parasequences, which in the studied marginal areas of the South Iberian Ramp were mostly sourced from the southern Tethyan realm. Therefore, the La Cañadilla Fm provides an example of a complex shallow marine to coastal system giving rise to a mosaic distribution of carbonate-mud dominated facies, with sedimentation mostly influenced by external factors resulting in a well-defined stratigraphic architecture. The similarities with modern analogous systems such as the Ten Thousand Islands of the Florida Bay are discussed in this paper.

Environmental conditions during the deposition of the diatomite –organic-rich marl alternation of the lower Messinian of the Lower Chelif Basin (Algeria) interpreted from microfossil assemblages and geochemistry

The lower Messinian diatomites and organic-rich deposits of the Lower Chelif Basin (North Algeria) constitute a record of the early stages of Mediterranean restrictions, i.e. when connections with the Atlantic were limited. Geochemical proxies and microfossil assemblages from the Ouilis section allowed us to discern three members and to confirm oxygen-depleted conditions for bottom waters during alternative deposition of diatomites and organic-rich marls. The high TOC and content of redox sensitive elements as well as the absence of benthic foraminifera during the deposition of members 1 and 2 point to oxygen-depleted conditions at the bottom. Water stagnation and anoxic conditions were more intense during deposition of Member 2, when enrichments of Mo and U were the highest. U/Th and authigenic U confirm anoxic conditions in this stratigraphic interval. These environmental conditions also affected oxygenation in the water column —the composition of radiolarian assemblage is altered in conjunction with an increased relative abundance of Nassellaria, especially Stychocorys. An increase in geochemical productivity proxies (Ba/Al and TOC) and Stychocorys is related to high productivity in the upper parts of the photic zone. Moreover, high diatom content in members 1 and 2 is congruent with eutrophic conditions in the Lower Chelif Basin.A noteworthy change occurred during the deposition of Member 3, indicated by higher CO3Ca content and a decrease in TOC and redox sensitive elements, probably related to the end of seawater stagnation and re-oxygenation of the sea bottom. The record of infaunal benthic foraminifera confirms oxygen availability at the sea bottom and in the sediment pore water. Infaunal benthic foraminifera such as Bulimina, Bolivina and Uvigerina, adapted to oxygen-depleted pore waters and mesotrophic to eutrophic conditions, prevail over typical epifaunal taxa such as Anomalinoides, Cibicidoides, Hanzawaia and Heterolepa, which prefer oxic and oligotrophic environments. Therefore, the colonizers of the sea bottom after anoxic conditions were benthic foraminifera that tolerated oxygen-depleted conditions and high nutrient content. The end of seawater stagnation and the re-oxygenation of the sea bottom could be attributed to a current that mixed deep and shallow waters, favouring upwelling processes, which is congruent with the dominance of buliminids.In the upper part of Member 3, planktic forms are represented exclusively by foraminifera, while the radiolarians disappear. Planktic foraminifera are dominated by intermediate dwellers such as Orbulina, Neogloboquadrina and Globigerina, whereas deep-dweller forms such as Globorotalia are secondary. This assemblage confirms a re-oxygenation of the water column in Member 3, being congruent with upwelling processes.

Geochemistry and organofacies characteristics of organic-rich chalky marl deposits, northern Jordan: Insights into Type II-S source rock

This study deals with organic matter in chalky marls of the Wadi Shallala Formation in northern Jordan. We report geochemical analyses (Total organic carbon, programmed pyrolysis, bitumen extraction, and pyrolysis–gas chromatography) for the chalky marls from 17 samples to provide information on the quantity, quality, the thermal maturity of the organic matter, their potential as petroleum source rocks. The chalky marl samples contain a significant amount of total organic carbon (TOC, max = 6.53%) and hydrogen index (HI) ranging from 300 to 702 mg HC/g TOC. The organic facies are mainly Types-II and -I kerogen with a potential to generate high amounts of oil. The dominance of such kerogen is consistent with significant amounts of fluorescent alginite macerals, observed under ultraviolet light microscopy. These organic facies are also confirmed by the Py-GC investigation, showing sulfur-rich Type II-S kerogen. The presence of weak carbon–sulfur (C-S) bounds in the kerogen molecules, however, suggests the generation of sulfur-rich oil at the early stages during the oil-generation window as reported by earlier works. Both geochemical maturity indicators (i.e., Tmax and PI) and the fluorescence color of the liptinite macerals indicate that the studied chalky marls in the outcropped section of the study area are still thermally immature, and maturity did not alter the organic-rich intervals to generate suitable oil for commercial production. Therefore, these organic-rich sediments in the locations having relatively deeper stratigraphic sections are likely to be promising source rocks and recommend for petroleum exploration and production in northern Jordan.

Sarmatian and Pannonian mollusks from Pécs-Danitzpuszta, southern Hungary: a unique local faunal succession

As the almost 200-year palaeontological research revealed, the geographical distribution of various fossil mollusk faunas in deposits of the late Neogene Lake Pannon displays a regular pattern. The lake basin was filled by lateral accretion of sediments, resulting in condensed sedimentary successions in the distal parts of the basin and successively younger shallow-water deposits from the margins towards the basin center. Exposed intra-basin basement highs, however, broke this strict pattern when they acted as sediment sources during the lake’s lifetime. The Mecsek Mts in southern Hungary was such an island in Lake Pannon during the early late Miocene. Deposition of the 200 m thick Sarmatian–Pannonian sedimentary succession in Pécs-Danitzpuszta at the foot of the Mecsek Mts was thus controlled by local tectonic and sedimentary processes, resulting in a unique succession of facies and mollusk faunas. A typical, restricted marine Sarmatian fauna is followed by a distinct freshwater or oligohaline interval, which, according to micropalaeontological evidence, still belongs to the Sarmatian. Although poor preservation of fossils does not allow firm conclusions, it seems that freshwater Sarmatian snails were the ancestors of the brackish-water-adapted early Pannonian pulmonate snail taxa. The successive “Sarmatian-type” dwarfed cockle fauna is similar to those widely reported from the Sarmatian–Pannonian boundary in various parts of the Pannonian Basin; however, a thorough taxonomic study of its species is still lacking. The bulk of the sedimentary succession corresponds to the sublittoral to profundal “white marls,” which are widespread in the southern Pannonian Basin. In Croatia and Serbia, they are divided into the Lymnocardium praeponticum or Radix croatica Zone (11.6–11.4 Ma) below, and the Congeria banatica Zone (11.4–9.7 Ma) above; this division can be applied to the Pécs-Danitzpuszta succession as well. Sedimentation of the calcareous marl, however, ceased at Pécs-Danitzpuszta at about 10.5–10.2 Ma ago (during the younger part of the Lymnocardium schedelianum Chron), when silt was deposited with a diverse sublittoral mollusk fauna. Similar faunas are known from the Vienna Basin, southern Banat, and other marginal parts of the Pannonian Basin System, but not from Croatia and Serbia, where deposition of the deep-water white marls continued during this time. Finally, the Pécs-Danitzpuszta succession was capped with a thick, coarse-grained sand series that contains mollusk molds and casts representing a typical littoral assemblage. This littoral fauna is well-known from easternmost Austria, northern Serbia, and northwestern Romania, but never directly from above the sublittoral L. schedelianum Zone. The fauna is characteristic for the upper part of the Lymnocardium conjungens Zone and has an inferred age of ca. 10.2–10.0 Ma. The Pécs-Danitzpuszta succession thus allows to establish the chronostratigraphic relationship between mollusk faunas that have not been observed in one succession nor in close proximity to each other in other parts of the Pannonian Basin.

On the Validity and Evolution of Assilina Species during the Ypresian–Lutetian: Example from Bir Dakhl, Eastern Desert, Egypt

AbstractThe genus Assilina is a taxon within the Nummulitacea that appeared early in the Ypresian (Early Eocene) and continued until the end of the Lutetian (Middle Eocene). Thus, this taxon could be useful for the chronostratigraphy of this time interval. Lower Eocene rocks in southern Galala, Egypt are exposed at Bir Dakhl. This section includes marl sediments with debris flow shallow‐marine facies deposits laid down during early Eocene times and includes fossils of large foraminifera: Assilina placentula Deshayes, 1838 and Nummulites burdigalensis de la Harpe, 1926. These are systematically treated, described and illustrated. Nummulites burdigalensis belongs to the N. burdigalensis group, and Assilina placentula belongs to the group of Assilina exponens. This assumption is based on qualitative morphology and quantitative measurements. Both species, together with Operculina libyca Schwager, 1883, enable the assignment of the Bir Dakhl (D5‐40 Section) to the Early Eocene, Ypresian (SBZ10 of Serra‐ Kiel et al., 1998) supporting an earlier opinion that Assilina placentula belongs to that zone in the calibrated larger foraminiferal biostratigraphic zonation.

GEOTECHNICAL PROPERTIES AND AGGREGATE QUALITY ASSESSMENT OF MARL DEPOSIT IN AFIKPO AREA, SOUTHEASTERN NIGERIA

Purpose: Marl is an impure limestone that is generally not good for cement production because of its low calcium carbonate content. Aggregates derived from marl deposit in Afikpo Area, Southeastern Nigeria, are currently being used in construction of concrete structures and highway pavements by construction companies and individuals. There is no published information on the suitability of the aggregates for such uses. The purpose of this study was to determine the suitability of the aggregates as components of concrete and highway pavements in terms of satisfying the non-swelling and acceptable strength characteristics / requirements.
 Methodology: Geotechnical tests including Atterberg limits (liquid limit, plastic limits and plasticity index), linear shrinkage and free swell were used to evaluate the swelling characteristics; while physico- mechanical tests including specific gravity, water absorption. Aggregate Crushing Values (ACV), Aggregate Impact Value (AIV) and Los Angele Abrasion Value (LAAV) were used to evaluate the strength characteristics. The field studies indicate that the marl deposit is associated with Ezeaku Formation of Lower Benue Trough. Results: Results of geotechnical tests indicate liquid limit, plasticity index, linear shrinkage and free swell values of 29.50%, 4.60%, 0.36% and 10.00%, respectively. Similarly, results of physico-mechanical tests indicate specific gravity, water absorption, ACV, AIV and LAAV values of 2.58%, 1.90%. 23.50% 29.45% and 42.70%, respectively.
 Unique contribution to theory, practice and policy: Since the results satisfy the non-swelling characteristics (plasticity index < 12%, linear shrinkage < 8% and free swell < 50%) and acceptable strength characteristics (water absorption < 3%, ACV < 30%, AIV < 30% and LAAV < 45%) requirements for good concrete and highway pavement aggregates, aggregates derived from marl deposit in Afikpo Area, Southeastern Nigeria, are strongly recommended to be used as aggregates in concrete and highway pavement construction.

Investigation of the Transformation of the Plant Ecosystem in the Vicinity of the Tsemesskaya Bay in the Black Sea Based on Remote Sensing Data

A brief description of the industrial and logistics center operating in the city of Novorossiysk on the coast of the Tsemesskaya Bay in the Black Sea is presented. According to remote sensing data, the area of open pit mining of rock dumps dumped during the development of three marl deposits for use at four cement plants was determined. According to the results of satellite imagery and analytical calculations, downward trends in changes in the density of vegetation cover in territories with natural landscapes adjacent to the territory of industrial facilities located on the coast of the Tsemesskaya Bay were revealed.

Tracking a drowning unconformity up to the peritidal zone: Proximal expression of the early Bajocian carbonate crisis in Morocco

The early Bajocian environmental crisis is marked by floral and faunal turnovers, and a positive carbon excursion recognized in both marine and continental archives. In the basinal setting of the Central High Atlas Basin, it is concomitant to a drastic drop of carbonate content, interpreted as a result of a severe carbonate demise event in neritic settings. In order to provide a carbonate platform perspective of this demise event, we have investigated a proximal–distal transect consisting of five sections of the Errachidia Platform, which represents upper neritic settings on the southern margin of the basin. New nannofossils and brachiopod findings, supported by organic matter carbon isotope chemostratigraphy, allow for the establishment of a high-resolution chronostratigraphic framework of the Errachidia Platform and a detailed reconstruction of carbonate factory evolution during the late Aalenian to middle Bajocian interval. The early Bajocian (Propinquans Zone) environmental crisis triggered a severe demise event which restricted carbonate production to supra-to intertidal settings, where microbial and peloidal limestones are the only trace of carbonate production. As a consequence, most of the platform is dominated by extended marl deposits that are usually interpreted as hemipelagic deposits. This observation demonstrates that caution must be exerted when interpreting the depositional environments of marl-dominated successions during time of neritic carbonate factory demise.

The Late Quaternary sediment successions of Llangorse Lake, south Wales

The last British-Irish Ice Sheet (BIIS) created a landscape with many sedimentary basins that preserve archives of paleoenvironmental and paleoclimatic change during the Last Glacial-Interglacial Transition (LGIT; ~18-8 ka BP). The typical lithostratigraphic succession of these archives is composed of minerogenic/allogenic sediments formed during cold climatic conditions and organic-rich/authigenic sediments during warmer climates. This paper presents a multi-core lithostratigraphy compiled from the extant lake and surrounding basin at Llangorse Lake, south Wales, a basin lying within the southernmost limits of the last BIIS. This lake contains one of the longest continuous terrestrial sediment successions in the UK. Uncertainty previously existed concerning the presence and distribution of sediments at the site related to the Windermere Interstadial (~14.7 to ~12.9 ka BP) and Loch Lomond Stadial (~12.9 to 11.7 ka BP). A new borehole survey demonstrates that LGIT-age sediments are present at the site with nekron mud (gyttja), corresponding to the Lateglacial Interstadial, deposited in the deeper part of the lake waters and that these deposits are equivalent in age to marl deposits found at shallower depths at the margins of the basin. These deposits are associated with warmer conditions experienced during the Windermere Interstadial and Holocene, whilst minerogenic-rich sediments were deposited during the colder climatic conditions of the Dimlington Stadial and the Loch Lomond Stadial with rangefinder radiocarbon dates confirming this attribution. A model of lake level changes shows that drainage of the Dimlington Stadial glacial lake caused the largest fall, but there was also a further, smaller lake level fall at the end of the Windermere Interstadial and/or the start of the Loch Lomond Stadial, before the level rose in the early Holocene. The lithostratigraphic results presented here form the framework for further paleoenvironmental and paleoclimatic research at Llangorse Lake.

Spatial distribution, controlling factors and failure mechanisms of the large-scale landslides in the urban area of Azazga city (northern Algeria)

The city of Azazga is facing extensive and damaging landslide hazard. The aim of this study was to investigate the inventory mapping, the deformation characteristics, the controlling factors and the failure mechanisms of the landslides in the urban area of Azazga based on field surveys, aerial photographs/satellite images interpretation and the exploitation of available data including rainfall database, boreholes, piezometers, inclinometers and laboratory tests. The prepared landslide inventory map indicates that the unstable urban perimeter covers an area of 281.6 ha which represents about 31% of the urban area. Analysis of the inventory data highlighted the action of two types of conditioning factors: (i) susceptibility factors represented by the presence of clay, marl deposits with low mechanical resistance characteristics, the presence of shallow aquifers, the morphology and steep slope, the tectonic features network and a dense hydrographic network; (ii) the triggering factors corresponds to the high intensity rainfall and the uncontrolled human activity. Statistical analysis of the relationship between the landslide occurrence and the landslide-conditioning factors shows that the highest density of landslides occur in quaternary scree and cretaceous clay flysch located on slopes ranging between 5° to 20°. The statistical results indicate that the highest concentration of landslides occurred in the highest rainfall classes ranging between 950 to 1050 mm. Additionally, the results showed the important role of the fluvial incision with more of the landslides occur at a distance of 50 m from the nearest rivers. These data also indicated that the high density of the landslides is concentrated in the farming and urban zones. The inclinometer measurement results reveal a deep rupture surfaces between 4 and 28 m located at the scree–flysch bedrock interface. According to the mechanism modes, landslides are controlled by the following: (i) the dip of the flysch formation layers, the schistosity planes and fractures downward slope direction; and (iii) the interface contact between the quaternary scree and flysch substratum. This work presents an exhaustive understanding of the causes, deformation characteristics and failure mechanisms of the large-scale landslides as a useful information for landslide hazard and risk mitigation.