Fluvial Origin Research Articles

New contributions to the knowledge of two riparian mosquitoes in northwestern Spain: Anopheles petragnani and Culex mimeticus (Diptera: Culicidae).

A study was carried out in 345 water ecosystems (rivers, streams, ditches, lagoons, ponds, puddles, rockpools, and artificial containers) throughout the autonomous community of Galicia (NW Spain) during different seasons between 2020 and 2023. The results revealed the first detections of Anopheles (Anopheles) petragnani Del Vechio, 1939 (n = 185) and Culex (Culex) mimeticus Noè, 1899 (n = 12) in the territory, allowing to update and expand the overall knowledge about their distribution and ecology. The breeding preferences of the species were analyzed considering habitat characteristics (land use, water body type, and degree of insolation), geographical variables (latitude, longitude, and altitude), and physical-chemical water parameters (temperature, pH, dissolved oxygen, electrical conductivity, salinity, total dissolved solids, and turbidity). In addition, the relationship between the occurrence of these species and other mosquitoes present in the study area was discussed. Anopheles petragnani is widely distributed in the region and shows breeding preferences for water bodies of fluvial origin, forest environments, and shaded situations. Culex mimeticus was detected sporadically breeding in a pond and in a river in the south of the region, both in industrial and agricultural land uses, and always exposed to the sun. Although the presence of these species may not currently pose a health risk in the region, it is important not neglecting their study since the adequate characterization of their larval biotopes is relevant regarding vector surveillance and control measures.

Quantitative facies analysis of a fluvio-aeolian system: Lower Triassic Buntsandstein Group, eastern France

Understanding the factors that control the temporal and spatial evolution of the Lower Triassic Buntsandstein Group, eastern France, is important not just for palaeoenvironmental reconstruction but also because it is an important reservoir for the lithium-rich geothermal brines in the Upper Rhine Graben region. The interval of interest in this study, the Lower Grès Vosgien Formation (LGV), is made up of c. 200 m of clastic deposits of mixed fluvial and aeolian origin. Given the proximity between the outcrops and the areas of mineral and heat exploration, this region offers a unique opportunity for quantitative analysis and correlation between outcrops and reservoirs. The LGV is the thickest Formation in the Buntsandstein Group. However, hitherto, no detailed architectural analysis has been published to reveal the controlling factors of its depositional elements. In this study, high-resolution facies analysis was applied to thirteen outcrops, and a core, to quantify fluvial and aeolian depositional architectures, and to comprehend palaeoenvironmental conditions during their deposition. Two facies associations were identified. The fluvial channel facies association, composed mainly of sandstones deposited in poorly confined, occasionally ephemeral channels, corresponds to 93 % of the total thickness. The analysis of >800 sets of strata characterised by lower-, transitional-, and upper-flow regime sedimentary structures, distributed within different architectural elements, enabled the distinction of temporal and spatial variabilities, and an estimate of fluvial palaeohydraulic characteristics. The wind- and water-laid facies association, which accounts for 7 % of the total thickness, records an architecture controlled by a fluctuating water-table level, and ephemeral floods. Results revealed that aeolian dunes and sand sheets accumulated in distinct temporal moments. The vertical trends, recorded in the core, indicate an upward increase in the frequency of intercalations between the two facies associations, and a decrease in the occurrences of thicker cross-bedded sandstone sets of fluvial origin, which, associated with the overall retrogradational stacking pattern of the LGV, is interpreted as the preserved record of a large distributive fluvial system (DFS). The occurrence of laterally extensive aeolian deposits, overlying fluvial deposits, is often associated by authors with periods of relatively more arid conditions at a regional scale. However, evidence indicates channel belt avulsion as an alternative interpretation for the establishment of the two facies associations. The findings enhance the knowledge about the depositional controlling factors in braided fluvial and aeolian systems, and improve predictive models that account for reservoir heterogeneity in accumulated successions of this type.

Can palaeosols reveal palaeoenvironmental variability of fluvial systems? An example from the upper portion of the Bauru Group (Upper Cretaceous, SE Brazil)

Palaeosols are common in sedimentary successions of continental origin, and notably they comprise the majority of the thickness of some accumulated successions of fluvial origin. Yet, detailed investigation of palaeosols and evaluation of their palaeoenvironmental significance are not routinely undertaken in detail in many sedimentological studies. A careful analysis of palaeosols may, however, reveal that sedimentary units, which appear similar if based solely on the facies analysis, indeed show strongly distinct palaeoenvironmental and depositional characteristics.This is the case of the upper portion of the Bauru Group, a 100–190 m-thick Maastrichtian red sandstone unit of fluvial origin, present over an area of c. 180,000 km2 in south-eastern Brazil. In this study, the palaeosols of this unit, which constitute 25–92 % of the succession by thickness, are used to decipher palaeoenvironmental climate conditions, sediment source areas, and relationships between pedogenic and depositional processes. Through the combined study of macroscopic, micromorphological, and geochemical aspects of the palaeosols and of facies analysis of the deposits, the upper portion of the Bauru Group succession is separated into three sectors: north-western, north-eastern, and south-eastern. Although these three areas are all characterised by similar lithology types and lithofacies, indicative of deposition in alluvial systems, the palaeosol analysis highlights that they were each characterised by different climate, different clastic source areas and different dynamics and interaction of the pedogenic and sedimentary processes. This research reveals the critical significance of the palaeosols for discriminating otherwise apparently similar depositional units.

The Mangking Sandstone Formation of Kuala Tahan to Kampung Bantal: Sedimentology and Depositional Environment

The Mangking Sandstone of Tembeling Group in the Kuala Tahan region records part of the infill of the continental extensional basin formed at the end of the Triassic. Described facies of this formation include sandy matrix conglomerate (that shows evidence of pseudoplastic debris flow and traction-dominated deposition), sandstones with trough, tabular and horizontal stratification, laminated and massive mudstone. Groups of associated facies are arranged into six distinct architectural elements (channel, sandy bedform, crevasse splay, laminated sand sheet, downstream and lateral accretion and floodplain fines), which are constant with a fluvial origin for the succession. The types of architectural elements present and their relationship to each other demonstrate that the Mangking Sandstone preserves a record of a meandering river system.

The cryptic stratigraphic record of the syn‐ to post‐rift transition in the offshore Campos Basin, SE Brazil

AbstractRift basins typically comprise three main tectono‐stratigraphic stages; pre‐, syn‐ and post‐rift. The syn‐rift stage is often characterised by the deposition of asymmetric wedges of growth strata that record differential subsidence caused by active normal faulting. The subsequent post‐rift stage is defined by long‐wavelength subsidence driven by lithospheric cooling and is typified by the deposition of broadly tabular stratal packages that drape any rift‐related relief. The stratigraphic contact between syn‐ and post‐rift rocks is often thought to be represented by an erosional unconformity. However, the late syn‐rift to early post‐rift stratigraphic record is commonly far more complex since (i) the associated tectonic transition is not instantaneous; (ii) net subsidence may be punctuated by transient periods of uplift; and (iii) strain often migrates oceanward during rifting until continental breakup is achieved with crustal rupture. Previous publications on the Eastern Brazilian marginal basins have not historically used the tripartite scheme outlined above, with the post–pre‐rift interval instead being subdivided into rift, sag and passive margin tectono‐stratigraphic stages. In addition, the sag stage has been previously described as late syn‐rift, early post‐rift or as a transition between the two, with the passive margin stage being equivalent to the classically defined post‐rift, drift stage. Two (rather than one) erosional unconformities are also identified within the rift‐to‐sag succession. In this work, we use 2D and 3D seismic reflection and borehole data to discuss the expression of and controls on the syn‐ to post‐rift transition in the shallow and deep water domains of the south‐central Campos Basin, south‐east Brazil. We identified three seismic–stratigraphic sequences bounded by unconformities, named lower and upper pre‐salt and salt. The lower pre‐salt interval is characterised by wedge‐shaped packages of reflections that thicken towards graben and half‐graben‐bounding normal faults. This stage ends with the development of an angular unconformity, inferred to form as a result of the onset of the oceanward migration of deformation. The upper pre‐salt is typically defined by packages of subparallel and relatively continuous reflections that are broadly lenticular and thin towards fault‐bound basement highs, but that locally contain packages that thicken against faults. The pre‐salt to salt contact is defined by an erosional unconformity that is largely restricted to basement highs, and which is inferred to have formed due to base‐level fall and uplift associated with local fault reactivation, resulting in the formation of channels of possible fluvial origin. Based on its geometries and seismic facies, we conclude that the lower pre‐salt interval is syn‐rifting and syn‐tectonic, deposited during active continental extension and upper crustal faulting affecting the entire evolving margin, whereas the overlying upper pre‐salt is syn‐rifting and post‐tectonic in the Campos Basin, deposited when extension and faulting had migrated seaward to the future location of the spreading centre. The results of our study support the arising notion that the syn‐rift sequence does not only display syn‐tectonic sedimentary packages, and thus the tripartite tectono‐stratigraphic model for rift development is too simplistic and cannot be applied when assessing rifts in the context of the regional development of continental margins.

Paleoenvironmental reconstruction of Late Cretaceous rivers, Dinosaur Park Formation, Alberta, Canada

Dinosaur Provincial Park is a UNESCO World Heritage Site with one of the richest vertebrate fossil accumulations globally. The “badlands”-style topography exposes Upper Cretaceous (Campanian) meander-belt deposits of the Dinosaur Park Formation, providing an excellent opportunity for sedimentological and three-dimensional stratigraphic analysis. One of the main unknowns regarding the depositional environments of the Dinosaur Park Formation, specifically the proximity to the fluvial-to-marine transition zone, has been the subject of extensive debate. Our study aims to refine paleoenvironmental reconstructions of Late Cretaceous rivers through facies and facies associations analysis, meander-belt architecture characterization, and paleohydraulic parameter calculations.We investigate a ~7 m thick single-story meander-belt interval of the Dinosaur Park Formation. Six facies, four facies associations, and two architectural elements (both point bars) were identified from 20 stratigraphic sections. In addition, paleohydraulic reconstruction of the formative river channel was completed by estimating bankfull channel depth and width, paleoslope, and backwater length.Contrasting with previous interpretations of deposition (partially or wholly) influenced by tides, these data allow us to demonstrate that the meander-belt deposits of the Dinosaur Park Formation were deposited in a fluvial environment upstream of the fluvial–marine transition zone. Inclined heterolithic strata (IHS) present in the area are of fluvial origin, adding to the growing body of evidence for heterolithic bedding in fluvial point-bar environments. The newly inferred depositional setting for the studied portion of the Dinosaur Park Formation changes our understanding of the paleogeography of the Western Interior Seaway in western Canada and will allow paleontologists to revise the reconstructions of dinosaur habitats and better constrain the taphonomy of these globally significant fossil accumulations. Additionally, this study contributes to the validation and development of a systematic approach to the paleoenvironmental reconstruction of ancient river systems based on paleohydraulic analysis.

COMMON AND RARE LOWER PLIOCENE AGGLUTINATED FORAMINIFERS OF PIEDMONT (NORTHWESTERN ITALY): DISTRIBUTION, TAXONOMY AND PALEOENVIRONMENT

Agglutinated foraminiferal taxa from five stratigraphic sections and eightheen small outcrops of Lower Pliocene deposits were quantitatively analyzed for paleoenvironmental purposes. The studied area is located in Piedmont, northwestern Italy, and includes the northeastern Monferrato, the southern margins of the Turin Hill, the Astigiano, the Albese and part of the Langhe. Studied samples were mainly collected in the marine Argille Azzurre (AA) Formation, and cover a time interval ranging from the MPl1 zone to the MPl4a subzone in the Pliocene Mediterranean Foraminiferal Zonation. Most of the agglutinated assemblages are dominated, or exclusively made, by calc-agglutinated infaunal species of elongated tapered or subcylindrical shape, mainly represented by Bigenerina nodosaria and Martinottiella communis. The deep-water infaunal Cylindroclavulina rudis, Eggerella bradyi and Martinottiella perparva characterized the open-sea basinal facies deposited in the central part of the Piedmont region during the earliest Pliocene. These taxa progressively decreased in abundance until to disappear, and were replaced in the upper silty succession by shelf taxa, dominated by Bannerella gibbosa and Textularia aciculata. In particular, T. aciculata showed its highest abundances in infralittoral to shallow circalittoral muddy sediments of probable fluvial origin, widespread in the Astigiano area, and could be suggested as a typical species of shallow marine delta deposits. Among the 42 agglutinated species here determined, Cyclammina cancellata and Reophax scorpiurus were seldom reported in previous works, Ammobaculites agglutinans, Ammoscalaria spp., Cribrostomoides subglobosus subglobosus, Haplophragmoides canariensis, Psammosphaera spp., and Psammolingulina papillosa were not previously found. The occurrence of these rare taxa could be the proxy of particular sea-floor conditions during the MPl3 zone, characterized by a locally active bottom circulation and mesotrophic waters.

High-resolution sedimentological and stratigraphic framework for the Pehuen Co Paleoichnological site, late Pleistocene, Buenos Aires, Argentina

The Pehuen Co Paleoichnological site (Buenos Aires Province, Argentina) contains one of the more diverse and well-preserved mammal and bird fossil footprint assemblages from the Late Pleistocene. The purposes of this paper were a detailed paleoenvironmental assessment of the footprint-bearing unit (middle member of the Agua Blanca Sequence) and to date key stratigraphic surfaces to constraint the temporal development of the site. A total of twenty-two detailed sedimentological sections were measured and correlated and five sediment and fossil remain samples were dated by the Optically Stimulated Luminescence (OSL) and Electron Spin Resonance (ESR) methods, respectively. The lower part of the local sequence represents dense to dilute alluvial deposits that were pedogenized. The middle part contains an alternance of sandy sheet-flood and lacustrine mudflat deposits with sand patches of eolian origin. Most of the fossil footprints with better preservation quality were recorded in the mudflats of a shallow lake sourced by unconfined fluvial currents. The participation of eolian deposits increases up section. Locally, a sandy plain of fluvial origin is developed at the top of the section. The new OSL ages along with a previous radiocarbon date led us to propose that sedimentation of footprint-bearing levels would have extended approximately between 28.5 and 12.0 ka. Reworked marine shell remains from the lowermost levels of site with fossil footprints gave considerably older analytical ages in the range of 97.6–62.5 ka, which is probably the maximum age for the middle member of the Agua Blanca Sequence. The “marine levels of Pehuen Co”, which are exposed at very low tides and contains in situ specimens of Ophiomorpha nodosa, are dated 7.0 ± 0.4 ka (OSL method). They reflect a Middle Holocene sea level rise in the area.

Buried channels under the northern Bohai Sea: Evidence for a great Bohai Paleolake during the late MIS3

Buried channels are widespread on continental shelves and potentially record Quaternary glacial–interglacial environmental changes. The Bohai Sea, an epicontinental basin, is extraordinarily sensitive to such environmental changes, but the evolution of buried channels there remains poorly understood. Here, combined seismic and sedimentological data were used to investigate the evolution of buried channels in western Liaodong Bay, northern Bohai Sea. We identified over six sets of channels, up to 15 m thick and up to 4 km wide, at different horizons within a terrestrial bed formed during the late Marine Oxygen Isotope Stage (MIS) 3 between 35 and 30 kyr BP. Most of these channels are interpreted as incised valley systems of fluvial origin, with complex combinations of fill facies. They were truncated on their tops by transgressive ravinements, which formed during base-level rise. Our findings suggest that these incised valley systems formed and evolved over multiple cycles of incision/filling controlled by the alternation of subaerially exposed and drowned environments during the late MIS3, and the contemporaneous shoreline advanced and retreated repeatedly within our study area. Given that sea level during this period was ∼10–45 m lower than the buried channels in our study area, the evolution of the multiple channels appears to be dominated by lake level fluctuations rather than global eustasy. We hypothesize that during late MIS3, the Bohai Basin transformed into a great paleolake (>39000 km2) as a result of falling sea levels, separating it from the Pacific Ocean, which is also supported by the microfossils in a core collected from the more basinward location. Our stratigraphic evidence also suggests that lake level fluctuations were intensive and of different amplitudes (∼5 to >15 m), which is consistent with climate proxy records. These fluctuations in the paleolake level were presumably a response to and therefore could provide implications for reconstructing regional climate dynamics.

Stratigraphic architecture and fluvial interpretations of the Upper Cretaceous (Turonian?) Middendorf Formation, Chesterfield County, South Carolina, U.S.A.

ABSTRACT The Upper Cretaceous (Turonian?) Middendorf Formation is a sand-rich stratigraphic unit of fluvial origin that forms a large aquifer in the U.S. Atlantic Coastal Plain. In Chesterfield County (South Carolina), which is the site of the type locality, the formation ranges in thickness from 66.5 to > 119.7 meters. The base of the formation is an unconformity above Paleozoic metasiltstone, and the upper contact is an unconformity above which lies sand of the Quaternary Pinehurst Formation. Outcrops display the following five facies assemblages: 1) sandstone to conglomeratic sandstone (fluvial bar and channel deposits), 2) beds of alternating laminae of sandstone and mudstone (fluvial overbank or floodplain deposits), 3) ≥ 1 m-thick beds of clay (swamp deposits, floodplain deposits, and/or sediment that accumulated in abandoned fluvial channels), 4) 0.2–0.5 m-thick planar to slightly undulatory beds of framework-supported sandstone with a mud matrix (traction-dominated current deposits at the top of fluvial bars, upper-flow-regime bedform deposits in subsidiary fluvial channels, or coarse-grained overbank deposits), and 5) sandstone to conglomeratic sandstone cemented by iron (interpreted as fluvial bar and channel deposits, with the iron cement being a diagenetic “groundwater ferricrete” that formed via the circulation of shallow groundwater and the oxidation of iron-bearing minerals). Kaolinite in various forms is pervasive throughout the formation and is interpreted as an early diagenetic phenomenon that formed by prolonged postdepositional weathering and flushing by meteoric water under a warm and humid paleoclimate. The fluvial system that formed the Middendorf Formation prograded into the area from the west or northwest from uplifted margins of Mesozoic rift basins and/or the Appalachian Mountains. This progradation was a response to a base-level fall and the sediment accumulated during base-level lowstand and subsequent early transgression. In Chesterfield County, the Middendorf Formation can be subdivided into three fining-upward sequences. Each sequence consists predominantly of medium to coarse sand with a greater abundance of gravel in the lower part of the sequence and a greater abundance of clay and silt beds in the upper part. Each sequence is interpreted as either a response to autogenic processes or a response to allogenic sea-level changes, specifically a higher-order (higher-frequency) progression from relative lowstand conditions to early transgression whereby coarse sand and gravel (e.g., fluvial bar and channel deposits) were preserved during initial lowstand conditions and a greater proportion of mud and finer-grained sand (floodplain deposits) were preserved during subsequent early transgression. The Middendorf Formation is correlative with several other kaolinite-rich fluvial sandstones in North America including the Raritan Formation in New Jersey, the Tuscaloosa Formation of the eastern Gulf of Mexico (Alabama, Mississippi, Louisiana), the Woodbine Formation of the central Gulf of Mexico (Texas), and the Frontier Formation of Wyoming. The accumulation and preservation of these formations occurred in response to a Turonian eustatic sea-level fall and subsequent transgression, and the early diagenetic kaolinite in these formations is attributed to similar warm and humid paleoclimate conditions.

Suspended particulate matter dynamics in the inner sector of a Ría under fair-weather conditions: A synthetic model

In this work, we analyse the sediment particulate matter (SPM) dynamics. This subject is poorly understood in the Rías Baixas system (NW Iberian Peninsula), thus the bottom sediment dynamics of the inner sector of a ría is investigated for the first time. The current, turbidity, temperature and salinity were measured from 15 June to 17 July 2009, in the Ría de Muros-Noia, the northernmost embayment of the Rías Baixas. The parameters were measured by two moorings placed in the central axis of the inner sector; one equipped with two current meters, at 0.4 m and 1 m above the bottom (mab), and the second mooring equipped with one current meter at 0.4 mab. The wave data inside the ría during the survey was obtained using a numerical model (SWAN) computed from available wave data in open waters (provided by Organismo Público Puertos del Estado, OPPE). The survey was characterized by upwelling and downwelling events and punctual precipitation periods. The mooring data revealed the alternation of different subtidal processes; deep-water upwelling, relaxation periods and a large downwelling. SPM of fluvial origin was transferred to the bottom from the surface under downwelling conditions, whilst the arriving of oceanic water under upwelling conditions showed lowest turbidity values. The subtidal circulation of the water masses inside the ría controlled mainly the bottom turbidity dynamics in the inner sector. The SW waves were likely to produce punctual resuspension in the shallowest areas, and the tidal currents only transported locally the SPM clouds when the subtidal circulation made it available in the bottom.

Change of sediment transport direction within the Rio Jaguaribe estuary, NE Brazil, by means of clay mineralogical analyses

The estuary of the Rio Jaguaribe (NE Brazil) is filled by a sediment sequence of more than 23 m and characterised by estuarine plains that – today - extend 30 km upstream.We investigated the sedimentary dynamics in the Rio Jaguaribe estuary since the early Holocene by means of clay mineralogical analyses, as well as sediment analyses from 11 sediment cores. The clay mineralogical approach proves to provide the most robust results. A transition of the illite/kaolinite peak area ratio from 0.3 to 1.8 within the vertical depositional record suggests a change of sediment transport direction over time. Whereas in the lower sequence marine influence dominates, characterised by the relatively high kaolinite content originating from the weathered Barreira formation at the coast, in the upper sequence sediments of fluvial origin dominate, which are characterised by the relatively high illite content originating from the crystalline rocks in the source area of the Jaguaribe river. The depositional architecture of the Holocene sediments of the Jaguaribe estuary shows a seawards prograding infill, assumed to have occurred since the mid-Holocene and supports studies suggesting a stagnating or slightly falling relative sea level (RSL) since ∼7000 BP.

Late-Middle Pleistocene Sedimentary Environment and Climate Variation in North Hebei Plain, China: Evidence from the SHBZK-1 Core

Thick Quaternary alluvial and floodplain sediments in north Hebei Plain provide important information for understanding local paleoenvironmental and paleoclimatic variations. A 120.8 m drilled core (SHBZK-1) was recovered to determine the late Pleistocene climatic fluctuations, sedimentary environment and their coevolutionary relationship. Laboratory analysis, including grain size distribution, magnetic susceptibility, and optical stimulated luminescence dating, was carried out. Lithofacies and grain size showed that the sediments are of fluvial origin and contain two subfaces: river sand bar and flood plain. The good correlation between magnetic susceptibility and grain size show that climate change is the main factor controlling the variation of sedimentary environment in Hebei Plain, rather than tectonic factors. Furthermore, variations of the magnetic susceptibility and lithofacies reflect the intensity and fluctuations of Asian monsoons and couple well with glacial-interglacial cycles, suggesting that the variation of ice volume in the Northern Hemisphere drives climate change in the Hebei Plain, which, in turn, regulates the variation of the sedimentary environment and facies through controlling precipitation changes, as well as the input amount of magnetic minerals. This research provides a useful continental archive for understanding the late Pleistocene environmental and climatic variation and suggests the prevalence of climate-driven environmental change.

Morphometric, hydrological characteristics and genesis of Lakes of the Povolzhskij section of the projected National Park Nizhegorodskoe Zavolzh'e

The article presents the results of researching of the morphometric and hydrological characteristics of a number of lakes in the territory of the Povolzhskij section of the projected National Park Nizhegorodskoe Zavolzh'e (Nizhny Novgorod region). The researched territory is located in the central part of the Nizhny Novgorod region in the left-bank part of the Volga River valley. Lakes are the landscape-forming framework of this territory. To date, reliable data, reflecting the features of the relief of the bottom of the lakes and their hydrological characteristics have been absent. During the research, a bathymetric survey of the lakes of the researched territory was carried out from the board of a boat, using an echo sounder, combined with a navigator. The results of field research were processed, using the geoinformation program QGIS, digital models of the relief of the basins of the researched lakes were created and their main morphometric and hydrological characteristics were calculated. Based on the analysis of morphometric characteristics of lakes and data on landscape features of their surroundings, were made conclusions about the fluvial origin of lake basins. The results of the research have both scientific significance, allowing detailed knowledge about the morphology and genesis of the lakes of the Middle Volga valley, and practical – being the centers of attraction of recreants in the projected national park, the lakes require a detailed research of morphological and hydrological parameters in order to effectively organize recreation.

Climate and Atlantic sea-level recorded in Southwestern Spain from 6.3 to 5.2 Ma. Inferences on the Messinian Crisis in the Mediterranean.

The Mio-Pliocene succession of Andalusia on the Atlantic coast (Guadalquivir Basin) is known as one of the former stratotype candidate for the Andalusian Stage, proposed during the seventies as the last stage of the Miocene. Its type section is located in Carmona, east of Seville. Our investigation includes the drilling of three cored boreholes, which provide bio- and magnetic-stratigraphic data in complement to pre-existing industrial information, and a high-resolution palynological analysis (pollen grains, spores and dinoflagellate cysts). The pollen flora and its climatic quantification provide the mean to correlate the section to the oxygen isotope curve from the Montemayor-1 borehole, located about 80 km to the West of Carmona. The variations in the ratio between dinoflagellate cysts and pollen grains are used to identify high and low oceanic levels, consistently with a recent paleobathymetric reconstruction based on foraminifera: the two lowest levels being successively marked by the deposit of a littoral calcarenite (the Calizza Tosca Formation) then by a subaerial erosive episode. Based on the correlation with the Montemayor-1 regional drilling, the two major lowerings in oceanic level observed at Carmona are linked with the two episodes of the Messinian Crisis. The interlocking position of the high-energy sandstone deposits inscribed in the Messinian valley leads to an assessment of a drop in the global oceanic level of about 114 m at the beginning of the paroxysm of the Messinian Crisis, amplitude to be moderated with respect to the potential effect of isostatic readjustements due to the Messinian Crisis. Comparisons are discussed with the amplitude of the Messinian Erosional Surface in the West-Alboran Basin which potentially remained suspended and fed with Atlantic waters during the height of the crisis and isolated from the rest of the almost totally dried Mediterranean Basin. The quantified climate constructed from the pollen records confirms that dry conditions existed before the Messinian Crisis in Southern Mediterranean latitudes including the Atlantic side, making the Mediterranean Sea climatically predisposed to desiccation. Atlantic sea-level variations observed in the Guadalquivir region and measured at Carmona suggest that global glacio-eustatism somewhat facilitated the onset and completion of the Messinian Crisis in the Mediterranean Basin. At last, this work allows to discriminate two regional erosive events: the first one, dated at 5.60 Ma, of fluvial origin in relation with global eustasy; the second one, submarine, occurred just before 5.33 Ma, and referred to the strain exerted by the Guadalquivir olistostrome.

Geomorphological Analysis and Distribution of Landform of Erbil Masterplan Layout, 2030

The detailed geomorphological study and mapping were done for Erbil Masterplan layout 2030, in order to be useful in planning urban development and various land uses to be in harmony with the instant expansion of Erbil city. The geomorphological map was constructed a scale1:320000 according to the basic geomorphic processes; structural, denudational, and fluvial origin. Erbil city Urban area is situated in the Low Folded Zone, surrounded from the north by Pirmam anticline –Bastora stream and from the south by Dimeer anticline -Shamamk plain and from the west bordered by Greater Zab River and from the east by hills and badlands of Shalgha-Bestana area. The pattern of processes divided the study area into three main landscapes that are different in rock exposure,topography,tectonics, and drainage pattern:Hilly and mountainous landscape zone; Mound and High Land Zone and; Alluvial plain landscape zone. The most complex landscape and landform of structural and erosional origin occupied the north, north-eastern, and western because of endogentic and exogenitic activity (uplifting, folding, faulting, high rate of rainfall and dense drainage pattern). The other area mostly contains landform of fluvial origin like alluvial plain, alluvial fan, and river terraces. Generally, the slope directions are towards the south and southwest, therefore the urban area mostly faced flood hazards during strong rainfall. For the first time in detail geomorphological map with different significant landforms are plotted using field data and various satellite images and digital elevation models,such as Aster, Quick Bird and google earth.

DEPOSITIONAL ENVIRONMENT OF THE TERTIARY KERRI – KERRI FORMATION IN THE GONGOLA SUB-BASIN, NORTHERN BENUE TROUGH: PEBBLES MORPHOMETRIC AND GRAIN SIZE ANALYSIS APPROACH

Pebbles have been reported in the Sandstones units of the Kerri - Kerri Formation, but their application as a tool for interpreting the depositional environment is limited. In this context, 510 quartz pebbles and 16 sandstone samples were collected for pebble morphometric and grain size analyses in order to assess the depositional environment of the formation. For the pebble morphometric study, the long (L), intermediate (I), and short (C) axes of each pebble were measured. For each pebble, four geometrical parameters related to depositional environmental studies were computed, these are: Maximum Projection Sphericity, Oblate Prolate Index, Coefficient of Flatness, and Disk - Road - Index. The standard sieving method was used to sieve the sandstone samples. Mean grain size (Mz), sorting (I), skewness (SKI), and kurtosis (KG) were determined as statistical parameters of the grain size. The mean value of the computed pebble shape parameters for the pebbles of the Kerri – Kerri Formation indicates that the pebbles were deposited in a fluvial environment. Based on the grain size analysis, the sediments were deposited by fluvial action with moderate to low energy of deposition setting closer to the source of the sediments. The bivariate plots show that all the pebbles and sandstone samples lie clearlywithin the river field, which suggests fluvial origin

Late Messinian submarine channel systems in the Levant Basin: Challenging the desiccation scenario

Abstract The question of whether the Mediterranean Sea desiccated during the Messinian salinity crisis (MSC) has been strongly debated for decades. In the Levant Basin, this debate was recently reignited in relation to the latest stage of the crisis after cessation of salt deposition. The desiccation supporters argue that salt truncation—and its subsequent burial by a latest Messinian, clastic-rich evaporitic unit—occurred subaerially on a desiccated seafloor. However, we show that this latest Messinian unit contains a dense net of channels with meanders, levees, and overspill deposits and is very similar to the turbidite channels observed on the modern seafloor. The aggradation characteristics of these buried channels (levee height, channel depth, and channel-floodplain coupling) indicate a marine rather than fluvial origin. Our conclusion adds to the findings of a previous study that salt truncation occurred in deep waters by dissolution. In a wider perspective, we suggest that the flush of clastics into the basin during the last stage of the MSC indicates a combination of wet climate and sea-level rise that started before the Zanclean (earliest Pliocene).

Sedimentological, mineralogical and geochemical investigation of Chichaoua’s bassin depot system: potential origin and provenance

High Atlas Rivers are common along the Atlas Mountains of Morocco and result from the combined effectof river flow, winds, vegetation and other meteorological conditions. In this paper, we study the texturaland compositional parameters of fluvial deposits, from the Chichaoua catchment across the Seksaoua riverbanks, and their provenance. Morphologically, they are in the form of current active river, Paleozoic deposits.To study the provenance of the grains, we opted for laboratory analyses including grain size, mineralogy,micro textures and micro morphology. Sands from active deposits showed very fine to medium averagegrain size and moderate sorting, while those from fluvial deposits showed fine to very fine average grainsize and very low sorting. The deposits studied showed the dominance of grain forms ranging from angularto freshly angular. As far as mineralogy is concerned, calcite is predominant in the sands on the right bankof the river, whilequartz is more abundant in the deposits on the left bank. In the active streams on the leftbank, other carbonates were also detected in the bioclasts such as aragonite, dolomite and magnesian calcite,suggesting a fluvial origin. The siliciclastic grains of the studied stream generations are likely to be ofTriassic, Jurassic and Quaternary units origin crossed by the Seksaoua River. Indeed, the results revealedthe presence of minerals such as albite, plagioclase, microcline and illite which could come from Triassic asalts which is often associated with Jurassic evaporates associated with Jurassic evaporite rocks. This studyhas suggested the probable origin of the sands that form these deposits based on the detailed study of theirgrains, which has not been studied in previous research in the area. Furthermore, this research is particularlyrelevant as it is part of the current research trend related to the understanding of the evolution of Plio-Quaternary atlasic fluvial systems in the world and may be applicable to other fluvial systems in the mountainranges of Morocco in the future.

Revisiting subglacial hydrology as an origin for Mars' valley networks

Although the nature of the early Martian climate is a matter of considerable debate, the presence of valley networks (VN) provides unambiguous evidence for the presence of liquid water on Mars' surface. A subaerial fluvial origin of VN is at odds with the expected phase instability of near-surface water in the cold, dry Late Noachian climate. Furthermore, many geomorphic properties of VN (e.g., deep U-shaped valleys with constant widths; longitudinal profile reversals) are inconsistent with surface water flow. Conversely, subglacial channels exhibit many of these characteristics and could have persisted beneath ice sheets even in a cold climate. Here we model basal melting beneath a Late Noachian Icy Highlands ice sheet and map subglacial hydrological flow paths to investigate the distribution and geomorphometry of subglacial channels. We show that subglacial processes produce enough melt water to carve Mars' VN; that predicted channel distribution is consistent with observations; and corroborate reversed channel gradient measurements of VN consistent with subglacial formation mechanisms. We suggest that, given a sufficient historical global water inventory and Late Noachian geothermal heat flux, subglacial hydrology may have played a significant role in the surface modification of Mars.Plain language summary. Thousands of valley networks on Mars appear to have been carved by flowing water, and exhibit branching characteristics akin to river networks on Earth. Their origins, however, remain enigmatic for two primary reasons. First, ancient Mars was potentially cold, dry, and unable to support liquid water on its surface. Second, many physical characteristics of the valleys are inconsistent with features formed by precipitation and runoff. On Earth, water flowing beneath ice sheets produces channels with similar characteristics to Mars' valley networks. Here we model the deposition and evolution of Martian ice sheets and show that melting at the ice sheet base is likely even under cold and dry surface conditions. The volume, regional distribution, and flow patterns of melt are consistent with the volume and dynamics needed to carve the observed valley networks. A subglacial origin for Mars' valley networks accounts for their formation in a cold, dry climate and produces valley characteristics that match observations.