Modeling of the Hydro-Sedimentary Dynamics of the Coastal and Port Area of Pointe-Noire (Republic of Congo)

The Jurassic upper Smackover ooid-lime-grainstone of the central Gulf Coast has been a major hydrocarbon exploration target for nearly half a century. Study of the geologic and sedimentologic framework, petrography, two-phase fluid inclusions, and trace element and stable isotope chemistry indicates the following diagenetic history. The upper Smackover is a blanket ooid grainstone ranging in thickness from 300 to 400 ft (91 to 122 m), and covering at least 4,000 sq mi (10,400 sq km). In the northern part of the Arkansas shelf, a regional meteoric water system was established in the grainstone shortly after deposition, and prior to significant burial. This meteoric water system gave way to conditions which were increasingly more marine toward the south near the Louisiana-Arkansas state line. The fresh-to-marine hydrologic gradient is responsible for the strong precompaction regional diagenetic overprint that eventually controlled available diagenetic pathways for the unit during burial. Three diagenetic zones are present: (1) a northern zone, dominated by oomoldic porosity and preburial spar cementation; (2) a southern zone, characterized by compaction effects, late subsurface cement, primary porosity preservation, and late secondary subsurface porosity generation; and (3) a transitional zone having characteristics common to both the northern and southern zones. During the shallow burial phase, compaction became increasingly more important to the south in zones dominated by marine connate fluid, whereas rock integrity and a secondary oomoldic porosity system had already been established in the northern zone. As burial increased, brine originating in the underlying Louann salt reached the shelf grainstone and began to displace the original connate fluid. The brine triggered the inversion to calcite of remaining grains and cement composed of unstable mineralogy. When the Louann brine had displaced the original connate fluid, CaSO4 replacement as gypsum and anhydrite was common across all three diagenetic zones. Also, precompaction fine cement associated with oomoldic porosity was recrystallized and reequilibrated with the concentrated brine. Localized replacement dolomitization may well have developed throughout the burial history of the sequence, but was most commonly postcompactional. Postcompaction poikilitic calcite cement and baroque dolomite were precipitated from the Louann brine under conditions of elevated temperature and pressure. As subsidence continued, organic material from the basinward equivalents of the upper Smackover lime-grainstone arrived on the shelf and catalyzed SO4 reduction, resulting in pyrite and galena replacement in the southern and transitional zones. As hydrocarbon maturation continued in the fine-grained equivalents of the upper Smackover, H2S and CO2 by-products of these processes began to increase in the brine of the southern and transitional zones, ultimately causing regional dissolution of existing carbonate, and significantly enhancing preserved porosity. Porosity in the northern zone was established early, and preserved through moderate burial. Although porosity is well developed, permeability has been largely destroyed by recrystallization. Dolomitization is a prerequisite for economic reservoir development in the northern zone. Porosity in the southern zone is solution-enhanced, preserved, primary, intergranular porosity. Compaction is the most important porosity destruction process. Compaction in the absence of an early diagenetic overprint is affected primarily by grain type, and secondarily by size and sorting. Pellets and oncolites compact easily, yet destroy porosity during burial. Ooids and rhodolites resist compaction during burial, therefore are related to porosity preservation. Grain-type distribution, as well as size and sorting, are controlled by depositional environment processes, with the most favorable areas for porosity development (concentrations of ooids and rhodolites) associated with early salt-related structural movement. Porosity distribution in the southern zone, therefore, can be outlined with the aid of geophysical techniques. Porosity in the transitional zone is early secondary, or preserved primary intergranular, or a combination. Porosity in this zone, therefore, is highly unpredictable, and a strong potential exists for diagenetic traps unrelated to structure or original depositional environment. Documentation of significant deep-subsurface secondary porosity possibly associated with hydrocarbon maturation, opens the potential for hydrocarbon exploration in deeply buried, carbonate-dominated basins. This would include carbonate rocks heretofore thought to be well below the depth of carbonate porosity maintenance because of lithostatic load.

The inter‐decadal variation of autumn rain of west China (ARWC) and its relationship with atmospheric circulation and sea surface temperature anomalies (SSTAs) was analysed. The intensity of ARWC shows significant inter‐decadal variability. The year 1990 is one of the abrupt change points of ARWC in both the southern and northern zone, and the year 2000 is another one in the northern zone. The inter‐annual correlation between the intensity of ARWC in the northern (southern) zone and the El Niño–Southern Oscillation continuously weakens (strengthens) from 1961. The relationship between the intensity of ARWC in the northern zone and atmospheric circulation of September–October mean significantly weakens after 2000, so does the relationship with the SSTAs in the equatorial central Pacific. On the contrary, the relationship between the intensity of ARWC in the southern zone and atmospheric circulation of September–October mean significantly strengthens after 1990, so does the relationship with the east–west contrast pattern of SSTAs in the equatorial central–western Pacific. The positive phase of the east–west contrast pattern of SSTAs in the equatorial central–western Pacific (i.e., when the tropical central [western] Pacific is colder [warmer] than normal) gradually strengthening and maintaining from the preceding spring to September–October is favourable for a stronger western Pacific subtropical high, which further facilitates northwards transportation of water vapour and provides better dynamic conditions for ARWC in the southern zone by strengthening the local Hadley circulation.

The pink cusk-eel (Genypterus blacodes), a benthic-demersal fish confined to the southern hemisphere, supports an important commercial fishery in Chile where it is exploited over an extensive geographic area. Although the fishery was originally divided into a northern (41o28′–47o00′S) and southern (47o00′–57o00′S) zone for the purposes of fisheries management, recent studies have reported significant differences in life history parameters between these zones. Individuals from the southern zone reached larger asymptotic sizes and possessed higher survival rates compared to the northern zone. We estimate and compare the gonadosomatic index (GSI), shape of the maturity ogive, and length at 50 % maturity (L50%) of female G. blacodes between management zones and across time using biological data collected from the industrial fleet between 1985 and 2009. Females in the northern zone had higher monthly mean GSI than females in the southern zone. Our analyses also revealed L50% to be significantly higher in the southern zone than in the northern zone from 1985 to 2009. The significant differences in life-history traits between fishery management zones agree with the trade-offs predicted by Charnov’s life history theory. Together these results provide additional support for the hypothesis that two separate stocks exist and suggest that females from the northern zone have developed a life-history strategy, which favours early maturation and a proportionally greater investment in reproduction than females from the southern zone.

The Eastern Pontide active continental margin extends along the eastern part of the Black Sea with an E–W trend and comprises the parallel oriented northern, southern and axial zones. Each zone is fault bound and distinguished by distinctive magmatism, lithofacies and stratigraphy. In the northern zone, from the coast of the Black Sea to Torul, the cessation of Liassic bimodal volcanism and accumulation of anoxic carbonates of the Valanginian–Barremian was followed by bimodal volcanism which evolved from a tholeiitic (TH)–calc-alkaline (CA) to high K–CA composition. These volcanics erupted sporadically in asymmetric deep basins until the end of the Senonian. In the southern zone, around Torul and Gümüşhane, Liassic bimodal volcanism and the accumulation of the Malm–Cenomanian platform carbonate was succeeded by Campanian volcanism, i.e. much later than volcanism in the northern zone. A second epoch of CA–high K–CA andesitic volcanism occurred in the southern zone and is intercalated with a Campanian red pelagic limestone which is also widespread in the northern zone, and known as the marker lithologic unit in the eastern Pontides. South of the southern zone, in the Bayburt–Maden area, the pelagic limestone of the Early Cretaceous and overlying ophiolitic olistostromal mélange (which contains Cenomanian MOR, WP and IA basaltic pillow lavas) are overlain by high–K calc-alkaline Campanian andesitic volcanic rocks, implying that the ophiolitic mélange was formed in a back-arc environment. The major and trace element geochemistry and REE patterns of the Upper Cretaceous volcanic rocks suggest a variation from hydrous IA to anhydrous back-arc melting conditions on the subduction zone and the migration of arc magmatism laterally from the northern to the southern zones during the Senonian. This change to dehydration melting and the migration of the subduction-related Late Cretaceous volcanism towards the south in the eastern Pontide Magmatic arc, requires a south-dipping subduction polarity during the Senonian. Copyright © 1999 John Wiley & Sons, Ltd.

Variations in andean andesite compositions and their petrogenetic significance

: This work unit develops, validates, and implements advanced numerical wave modeling technologies which provide the USACE reliable and accurate wave estimates, and evaluates wave processes affecting navigation projects, coastal inlets and channels, ports and harbors and coastal beaches. It conducts basic research on coupling these wave models with flow and sediment transport models to calculate waves and currents for design and operation of channels, jetties, ports/harbors, and coastal morphology change. This work unit develops capabilities for meteorological and oceanographic data analyses that are necessary for short- and long-term simulations of coastal inlet hydrodynamics and navigation processes, and implements these technologies in the form of web-based tools, WaveNet and TideNet. It continually upgrades the Coastal Modeling System s (CMS) wave model CMS-Wave, a phase-averaged spectral wave model, and BOUSS-2D, a Boussinesq-type nonlinear wave model. These models are required for calculation of waves over shallow reefs and porous structures with variable roughness, infra-gravity waves, runup/overtopping, and wave asymmetry. Functional performance of USACE navigation projects can be evaluated with these models when coupled to flow and sediment transport models. Using laboratory and field measurements, the work unit verifies and validates the upgraded models for release to users. The work unit is developing WaveNet and TideNet, two web-based tools to access, visualize, and process wind, wave, and tide data for USACE project applications and R&D needs.

To better understand the nutrient distributions in the hyporheic zone of a large shallow eutrophic lake (Lake Taihu) and the potential drivers, the total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) were investigated in March and December 2016. Spatial differences in the TN and TP contents existed in the hyporheic zone, particularly between the eastern and southern zones and the western and northern zones. The TOC/TN ratios in the western, northern, and central zones were mostly <8 and even reached 4, indicating that organic matter originated from aquatic organisms and algae, whereas those in the southern and eastern zones exhibited wide ranges, indicating complex pollution sources. The chloride depth profiles suggested that upwelling hyporheic flow potentially occurred in the southern, western, and northern zones, while alternating flow directions occurred in the eastern zone and no flow or weak flow occurred in the central zone. Compared to the 1st investigation, the TOC, TN, and TP in sediments in the 2nd investigation increased by 13%, 41%, and 87%, respectively, and these changes were mostly due to large hyporheic fluxes with high nutrient concentrations from shallow groundwater. The behavior of the hyporheic zone as an active pollution source/sink due to hyporheic flow should be considered in the comprehensive management of Lake Taihu. PRACTITIONER POINTS: Depth profiles of nutrients differed between sampling sites and between zones of Lake Taihu due to different pollution sources. Nutrients in sediment increased largely during winter compared to spring due to potential groundwater pollution through upwelling flow. No significant difference in sediment total organic carbon and ratios of C/N indicates a similar internal pollution source lake wide.

To assess the inter-laboratory comparability and intra-assay reproducibility of full blood count (FBC) results. Exploratory cross-sectional study. Three and two selected medical laboratories in the northern and southern zones, respectively. Forty-nine individuals per zone; 16 type 2 diabetes mellitus, 16 with HbAS haemoglobin type and 17 normal samples. Each sample was run eleven times through the analysers in the participating laboratories to evaluate intra-laboratory reproducibility and comparability of FBC results. Intra-laboratory reproducibility was evaluated using %coefficient variation (%CV). Interlaboratory comparisons were assessed through t-test or One-Way ANOVA for two-sample and three-sample tests. All statistical testing was undertaken using the two-tailed assumption. Statistically significantly different haemoglobin levels were estimated in both northern and southern zones (mean difference 0.00 g/dL to 3.75 g/dL vs 0.18 g/dL to 1.92 g/dL respectively). Also, total WBC counts significantly differed across laboratories in both northern and southern zones (mean difference 0.15 ×109/L - 3.86 ×109/L vs 0.02 ×109/L to 1.39 ×109/L respectively). Furthermore, platelet counts significantly differed across the participating laboratories in the northern and southern zones (mean difference 0.40 ×109/L to 299.76 ×109/L vs 5.7 ×109/L to 76.9 ×109/L respectively). Moreover, there was evidence of non-reproducibility of results within the respective laboratories in each zone as the respective %CV were outside the acceptable limits. The intra-laboratory non-reproducibility and inter-laboratory non-comparability of FBC results highlight the need to establish a national quality assessment scheme to harmonise laboratory practices nationwide. This study was funded by the University of Cape Coast Individual-Led Research Support Grant (RSG-INDI-CoHAS-2019-107).

Climate change and variability pose significant threats to agricultural production, particularly in regions heavily dependent on rainfed agriculture like Senegal. The problem addressed in this study revolves around the impact of climate-related risks on agricultural yields in the Senegalese Groundnut Basin as a key agricultural region. Daily rainfall, temperatures, and yield over 1991–2020 were used. The data were analyzed using multiple regression, trend analysis, and correlation approaches. The results indicate that the overall seasonal precipitation increases over time (98 mm in the north and 103 mm in the south). However, we found that the south Groundnut Basin has a much slower seasonal precipitation rate than the northern zone. Our results also show that the northern zone exhibits a more consistent and predictable growing season, with onset and offset, in contrast with the southern zone, which shows higher variability. The analysis further reveals that both the northern and southern zones are experiencing a warming trend, with the southern zone showing a more pronounced increase in maximum temperatures (+0.7 °C) than to the northern zone (+0.4 °C). Estimates from the regression analysis revealed that total seasonal precipitation and maximum temperature positively and significantly influence groundnut, millet, and maize yields in the northern and southern zones. All the other weather-related parameters have different influences depending on the zone. These findings highlight the heterogeneous nature of the study area and the significant role climatic factors play in crop yield variability in the Groundnut Basin. Understanding these influences is crucial for developing targeted agricultural strategies and climate adaptation measures to mitigate risks and enhance regional productivity. The study provides valuable insights for policymakers and farmers aiming to improve crop resilience and sustain agricultural outputs amidst changing climatic conditions.

This article presents the results of groundwater site evaluation scheme and quality assessment of coastal aquifers in Calabar, South-eastern Nigeria based on ground water potential index (GWPI) scale, developed for this study. The GWPI consists of ten input parameters, namely: lithofacies (L), aquifer thickness (b), transmissivity (T), storativity (S), specific capacity (SC), static water level (SWL), formation resistivity (FR), chloride (Cl) contents, total dissolved solids (TDS) and Escherichia coli (E-coli). The groundwater potential index (GWPI) is computed as the sum of the products of weights and ratings assigned to each of the input parameters. The GWPI index varying between 20 and 60, is divided into three classes: high (> 40), medium (30-40), and low (< 30). The GWPI index, is then used to demarcate the study area into three hydrogeologic ground water potential zones. These are: (i) Northern zone 1 (transitional, low GWPI) (ii) Central zone 2 (coastal plain sands, high GWPI) (iii) Southern zone 3 (coastal alluvium, medium GWPI). The central zone 2 has the highest GWPI rating. The implication of this rating is that the aquifers in the central and southern zones 2 and 3 are more prolific water bearing than the transitional zone 1 that lies between the Coastal Plain Sands and the argillaceous sediments of the Calabar Flank. This is in agreement with the mean specific capacity (SC) and transmissivity (T) recorded for the central (355.6 m3/d/m, 2640 m2/d); southern (150.0 m3/d/m; 2150 m2/d) and northern (52.1 m3/d/m, 750 m2/d) zones respectively. Lithofacies, saturated thickness of the aquifer, static water level, transmissivity and storativity are the most important parameters which influence ground water availability in the study area. The GWPI results further reveal that E-coli (3-50counts/100ml), chloride (Cl-) (2.5-21.0mg/l) and static water level (SWL) (2.3-28.7m) remain the most significant parameters that contribute to groundwater pollution particularly in the southern zone of the study area. In the near future, water quality in aquifer will be affected due to poor management of human waste-disposal/salt water intrusion, thereby limiting the availability of potable water for domestic and industrial uses.

This study aimed to assess the prevalence and levels of aflatoxin B1 in broiler meat and feed samples from various zones of Sindh, Pakistan, conducted at Sindh Agriculture University, Tandojam, during 2022-2023. A total of 360 broiler meat and feed samples, with 120 from southern, central, and northern zones, were collected from retail shops and poultry farms. All samples were screened for aflatoxin B1 using the ELISA Bio-Shield Total Extra Sensitive Kit. Negative samples were spiked with 5 and 10g/kg aflatoxin B1 for validation. The southern zone had the highest contamination of aflatoxin B1 in broiler meat (58.33%; 36.50±2.08 µg/Kg) and feed (67.50%; 66.20±1.15 µg/Kg), followed by the central zone (40.00%; 32.60±1.64 µg/Kg) and the northern zone (25.00%; 20.90±2.82 µg/Kg). Contamination levels in feed samples were also higher in the southern zone compared to central (48.30%; 56.25±0.87µg/Kg) and northern (28.30%; 47.55±1.50 µg/Kg) zones. The aflatoxin B1 levels in both meat and feed samples exceeded the FDA-recommended limit of 20 µg/Kg, posing a significant risk to food safety. These findings highlight the urgent need for a monitoring plan to mitigate aflatoxin contamination in broiler meat, poultry products, and feedstuffs across Sindh, Pakistan, to ensure safer food production.

This report documents a numerical modeling investigation for dredged material from nearshore borrow areas and placed on Folly Beach adjacent to Stono Inlet, South Carolina. Historical and newly collected wave and hydrodynamic data around the inlet were assembled and analyzed. The datasets were used to calibrate and validate a coastal wave, hydrodynamic and sediment transport model, the Coastal Modeling System. Sediment transport and morphology changes within and around the immediate vicinity of the Stono Inlet estuarine system, including sand borrow areas and nearshore Folly Beach area, were evaluated. Results of model simulations show that sand removal in the borrow areas increases material backfilling, which is more significant in the nearshore than the offshore borrow areas. In the nearshore Folly Beach area, the dominant flow and sediment transport directions are from the northeast to the southwest. Net sediment gain occurs in the central and southwest sections while net sediment loss occurs in the northeast section of Folly Island. A storm and a 1-year simulation developed for the study produce a similar pattern of morphology changes, and erosion and deposition around the borrow areas and the nearshore Folly Beach area.

Magnetic and petrofabric studies in the multiply deformed Thomson Formation, east-central Minnesota

The Southern Dabieshan Terrane (SDT) has previously been divided into high‐pressure (HP) and ultrahigh‐pressure (UHP) terranes, and its regional extent and the tectonic nature of its boundaries are hotly debated topics. In this study, an eclogite‐bearing area of 100 km2 near Taihu is mapped in detail, and divided into Northern, Middle and Southern Zones on the basis of lithological characteristics. The Northern Zone consists of epidote‐biotite gneiss and eclogite blocks, the Middle Zone includes granitic gneiss, biotite gneiss, eclogites and amphibolite, and the Southern Zone is composed mainly of garnet‐bearing mica schist. The eclogites occur mainly as lens or blocks in the Northern and Middle Zones. The peak P–T conditions for 61 eclogite samples across the area are estimated using the Grt‐Cpx Fe2+‐Mg thermometers and the Grt‐Cpx‐Phe barometers. The results indicate three different P–T regions: 2.82–4.09 GPa/759–942 °C in the Northern Zone, and 2.00–3.54 GPa/641–839 °C in the granitic gneiss and 1.38–2.36 GPa/535–768 °C in the biotite gneiss from the Middle Zone. Combined with the spatial distribution of eclogites across the area, the P–T values for eclogites increase continuously from the south to the north, defining a reference ‘geotherm’ of 5 °C km−1. However, some unreasonable apparent gradients can be established along two south–north profiles across the area, and display a P–T difference between the Northern and Middle zones. On the basis of the average P–T data for eclogites across the area, a gap of at least 0.3 GPa/20 °C exists between the Northern and Middle zones. By contrast, the P–T values of eclogites from the Middle zone show a coherent pattern with transitional characteristics from HP in the south to UHP in the north. We suggest that the SDT was a coherent slab during subduction, and was broken up by a major fault during exhumation, which was formed under UHP metamorphic conditions.

The role of ridge subduction in determining the geochemistry and Nd–Sr–Pb isotopic evolution of the Kodiak batholith in southern Alaska