Northwestern Tunisia Research Articles

Seasonal incidence of the leaf miner Liriomyza cicerina Rond (Diptera: Agromyzidae) in chickpea fields and effects of climatic parameters, chickpea variety, and planting date on the leaf miner infestation rate

In the last few years, chickpea yield losses in North Africa due to the chickpea leaf miner Liriomyza cicerina (Diptera: Agromyzidae) have exceeded 40%, especially for spring crops. However, the biology and ecology of this insect in Tunisia have not been studied. Thus, in the present work, the population dynamics of L. cicerina and the damage caused by this pest to both winter and spring chickpea crops (Cicer arietinum L.) in North Tunisia were investigated. The study was conducted according to a split plot design during the 2015, 2016, and 2017 crop seasons in Beja (northwestern Tunisia). Five chickpea varieties—three winter varieties (cv. Beja1, cv. Nour, and cv. Nayer) and two spring varieties (cv. Amdoun1 and an advanced line, X07TH106-A3)—were grown. Results showed that L. cicerina produces three annual generations and that the environmental conditions—especially climatic parameters—significantly influence the abundance and distribution of this pest on both winter and spring varieties of chickpea. Infestation with leaf miners was particularly prominent during the flowering and pod-setting stages, with mean infestation rates of 70.2% and 94.6% observed for winter and spring crops, respectively. The infestation rate increased when the sowing date was delayed. Furthermore, results revealed that agromorphological characteristics were significantly correlated with the infestation rate. This study provides important insights into the population biology of L. cicerina, the damage caused by this pest, and its ecology—information that is required to establish a robust and effective pest control program.

Gravity contribution to the Mejerda foreland basin, Northwestern region of Tunisia

The Mejerda basin in northwestern Tunisia is located between the Tell and Atlas Mountains and contains structures related to the complicated tectonic history of the study region. The Mejerda contains compressional structures related to the Cenozoic collision between Europe and Africa, and strike-slip faults related to extensional tectonics. As a result of the varied tectonic history, there has been numerous models of the basin formation ranging from simple grabens, pull-apart basins and foreland basins. In order to constrain the subsurface structure of the basin, a gravity analysis consisting of the construction of residual gravity anomaly maps, estimated depths from upward continuation and Euler deconvolution, and detailed two-dimensional forward models. The gravity analysis was constrained by a seismic reflection profile and a deep well. The map analysis indicated two separate basins, one called the Quaternary basin and another called the Pliocene basin. Based on the gravity depth analyses and the gravity forward modeling, and the residual gravity anomaly map, these basins were between 2.5 and 3 km thick, and separated by gravity maxima probably due to uplift of Triassic and Cretaceous sediments related to compressional tectonics and evaporitic movement. The Euler deconvolution analysis imaged a number of lineaments, interpreted to be faults, that trend in the NE and NW directions and these faults basically delineate the basins. Results confirm that the Mejerda basin is a wedge-top basin located in the foreland side of the Tellian thrust belt and consists of two separate basins whose origin was mostly determined by thin-skin compressional tectonics.

Flood mapping using hydraulic modeling and Sentinel-1 image: Case study of Medjerda Basin, northern Tunisia

In northwestern Tunisia, floods are the most widespread natural hazard. Indeed, this problem is posed seriously in the Medjerda basin. In fact, the plain of Jendouba - Bou Salem is the most affected area by this plague. It has the form of a shallows that collects runoff water and promotes flood extent and duration. So the main objective of this study is to determine the extent of the hydraulic hazard through the flood mapping of February 2015 event which has seriously affected the urban and peri-urban landscape of the plain. The hydraulic hazard extent mapping was determined through the HEC-RAS model. It's one of the most popular free hydraulic models developed by the Hydrological Engineers Center of the U.S. Army Corps. The new version (HEC-RAS v-5) is a two dimensional (2D) model based on the resolution of hydraulic Saint Venant which can simulate floodplain inundation, determine the water surface elevation and velocity distribution of floods. It allows modeling flow with permanent and non-permanent free surface by evaluating water flows and heights over the all sections of a river so it allows to integrate hydraulic works (bridge, dam …).The result showed that this flood reached heights of more than six (6) meters in flooded areas. The result from the HEC-RAS model was validated using the Sentinel-1 radar image acquired on February 28th, 2015.The study shows the applicability and the capabilities of the 2D HEC-RAS version for flood studies.

Identification of winter moth (Operophtera brumata) refugia in North Africa and the Italian Peninsula during the last glacial maximum.

Numerous studies have shown that the genetic diversity of species inhabiting temperate regions has been shaped by changes in their distributions during the Quaternary climatic oscillations. For some species, the genetic distinctness of isolated populations is maintained during secondary contact, while for others, admixture is frequently observed. For the winter moth (Operophtera brumata), an important defoliator of oak forests across Europe and northern Africa, we previously determined that contemporary populations correspond to genetic diversity obtained during the last glacial maximum (LGM) through the use of refugia in the Iberian and Aegean peninsulas, and to a lesser extent the Caucasus region. Missing from this sampling were populations from the Italian peninsula and from North Africa, both regions known to have played important roles as glacial refugia for other species. Therefore, we genotyped field‐collected winter moth individuals from southern Italy and northwestern Tunisia—the latter a region where severe oak forest defoliation by winter moth has recently been reported—using polymorphic microsatellite. We reconstructed the genetic relationships of these populations in comparison to moths previously sampled from the Iberian and Aegean peninsulas, the Caucasus region, and western Europe using genetic distance, Bayesian clustering, and approximate Bayesian computation (ABC) methods. Our results indicate that both the southern Italian and the Tunisian populations are genetically distinct from other sampled populations, and likely originated in their respective refugium during the LGM after diverging from a population that eventually settled in the Iberian refugium. These suggest that winter moth populations persisted in at least five Mediterranean LGM refugia. Finally, we comment that outbreaks by winter moth in northwestern Tunisia are not the result of a recent introduction of a nonnative species, but rather are most likely due to land use or environmental changes.

GIS-based landslide susceptibility mapping using bivariate statistical methods in North-western Tunisia

AbstractThe Tunisian North-western region, especially Tabarka and Ain-Drahim villages, presents many landslides every year. Therefore, the landslide susceptibility mapping is essential to frame zones with high landslide susceptibility, to avoid loss of lives and properties. In this study, two bivariate statistical models: the evidential belief functions (EBF) and the weight of evidence (WoE), were used to produce landslide susceptibility maps for the study area. For this, a landslide inventory map was mapped using aerial photo, satellite image and extensive field survey. A total of 451 landslides were randomly separated into two datasets: 316 landslides (70%) for modelling and 135 landslides (30%) for validation. Then, 11 landslide conditioning factors: elevation, slope, aspect, lithology, rainfall, normalized difference vegetation index (NDVI), land cover/use, plan curvature, profile curvature, distance to faults and distance to drainage networks, were considered for modelling. The EBF and WoE models were well validated using the Area Under the Receiver Operating Characteristic (AUROC) curve with a success rate of 87.9% and 89.5%, respectively, and a predictive rate of 84.8% and 86.5%, respectively. The landslide susceptibility maps were very similar by the two models, but the WoE model is more efficient and it can be useful in future planning for the current study area.

Assessment of land management practices on soil erosion using SWAT model in a Tunisian semi-arid catchment

PURPOSE: Soil erosion is a widespread problem that has threatened the majority of Mediterranean countries. Land management practices are widely used to minimize runoff and sediment loads at the catchment scale. However, their effectiveness cannot be easily assessed. Thus, models have been applied to estimate their impact on runoff dynamics and soil erosion and to identify the optimal conservation measure that can be used for specific land uses. MATERIALS AND METHODS: This study applied the SWAT model to spatially predict soil erosion over the Sarrath River catchment (1491 km²) in northwestern Tunisia, and to evaluate the effectiveness of different land management practices in reducing runoff and soil erosion. Calibration and validation of the model were done at the monthly scale for the period 2001–2008. Seven scenarios of best management were proposed including three combined scenarios. Each scenario needed a modification of one or more input parameters in SWAT model. The baseline values, scenario 0, represent the existing conditions. RESULTS AND DISCUSSION: The SWAT model was successful in reproducing water flow, and a good correlation between simulated runoff and sediment yield was observed. Simulated average soil erosion rate for the baseline conditions was 5.1 t ha⁻¹ year⁻¹. It was found that only 10% of the total area can experience high and very high soil erosion risk, but disproportionately contribute to the maximum amount of the total soil loss (71%). Implementation of individual scenarios reduced runoff from 5 to 22% and sediment loads from 5 to 30% from the baseline scenario. Combining different scenarios resulted in greater reduction. The highest reductions were achieved when combining reforestation of degraded lands and bare lands with contour farming and parallel terraces on agricultural fields. CONCLUSIONS: Simulation results showed that land conservation measures could reduce sediment yield by about 5 to 43% and runoff by 5 to 32%. For individual scenarios, parallel terraces were the most effective both for runoff and for sediment loss, followed by forestation. The best results were obtained for combined scenarios. Targeting the prioritized sub-catchments, reductions reached 78% for runoff and 88% for sediment loss in sub-catchment 4.

Impacts of land use and topography on soil organic carbon in a Mediterranean landscape (north-western Tunisia)

Abstract. This study evaluates the impact of land use and topographic features (slope and aspect) on soil organic carbon (SOC) within the Wadi Beja watershed in north-western Tunisia. A soil spectral library was set up to assess the variation in the SOC for 1440 soil samples from four land use types (field crops, permanent crops, forest, and grazing land), three slope categories (flat, moderate, and steep) and two aspects (north- and south-facing). For field crops, only one factor – slope – significantly affected SOC, with SOC content in north-facing areas appearing to be higher in flat areas (0.75 %) than in hilly areas (0.51 %). However, in south-facing areas, SOC content was also higher in flat areas (0.74 %) than in hilly areas (0.50 %). For permanent crops, which were inter-planted with field crops, the slope significantly affected SOC content, which improved to 0.97 % in flat north-facing and 0.96 % in flat south-facing areas, scoring higher than hilly south- and north-facing areas (0.79 %). In the grazing land use system, both of the investigated factors – aspect and slope – significantly affected the SOC content, which was significantly higher in flat areas (north-facing: 0.84 %, south-facing: 0.77 %) than in hilly areas (north-facing: 0.61 %, south-facing: 0.56 %). For the forest, none of the factors had a significant effect on SOC content, which was higher in flat areas (north-facing: 1.15 %, south-facing: 1.14 %) than in steep areas (1.09 % in north-facing areas and 1.07 % in south-facing areas). This study highlights the ability of visible and near-infrared (VNIR) spectroscopy to quantify C in diverse soils collected over a large diverse geographic area in order to indicate that calibrations are feasible, and therefore, assessing the variation of SOC content under land use and topographic features (slope and aspect) will result in better sustainable land management planning.

Neogene-Quaternary structuring of the Kalaa Khesba Graben, northwestern Tunisia: A push-up inversion structure

Interpretation of lithostratigraphic, seismic and gravity data from Kalaa Khesba Graben shows (i) lateral and in-depth variation of the lithostratigraphic series, (ii) complex structuring of faulting. Reverse faults affected Paleocene to Quaternary horizons with a duplication of Eocene-Paleocene series occurred at subsurface evidenced within well W6. Isochron, isovelocity and isobath maps, combined with gravity data, show subsurface structures oriented predominantly NW-SE to NS and NE-SW to EW. Faults and horizons on the seismic lines, superimposed to gravity lineaments, reveal negative anomalies occurring at shallow depth. Such features may reflect the existence of low density Neogene-Quaternary series, strike-slips and thrust faults within Kalaa Khesba Graben. Depths deduced from Euler deconvolution solutions vary from 0.5 to 4 km. At subsurface, well log data located in the center of the graben, ensured the presence of Triassic bodies. A model of initiation of Kalaa Khesba Graben through a N160° σ1 transpression is proposed.

Small benthic foraminiferal biostratigraphy and palaeoecology during the Campanian-Maastrichtian transition in north-western Tunisia

Campanian-Maastrichtian (C-M) sediments in the Kalâat Senan area (north-western Tunisia) include rich microfauna. Small benthic foraminifera (SBF) analysis at the Wadi Necham (ON) section reveals significant biostratigraphic and palaeoecological changes during the C-M transition. A progressive evolutionary trend within the Bolivinoides lineage allowed us to establish the late Campanian B. decoratus Interval Range Zone (IRZ) and two successive zones in the early Maastrichtian, namely the B. miliaris IRZ and the B. draco Total Range Zone (TRZ), which span the standard planktonic foraminifera Gansserina gansseri IRZ. Foraminiferal semiquantitative data from the C-M transition interval at the studied section yield high values of planktonic/benthic (P/B) ratios (92%-98%) suggesting an upper to middle bathyal depositional palaeoenvironment. Assemblages of such a deep environment comprise diversified epibenthic and endobenthic taxa indicating major changes across and above the C-M transition. During the late Campanian (Bolivinoides decoratus Zone) endobenthic morphogroups dominate (71%) the assemblages as compared to epibenthic morphogroups, which reach 29%. In contrast, the abundance of epibenthic morphogroups increases to 40% just above the C/M boundary (Bolivinoides miliaris Zone) and suggests cooler and more oxygenated conditions on the sea floor. Epibenthic and endobenthic abundances fluctuate in opposite trends (40%-60%) throughout the early Maastrichtian (B. draco TRZ). These variations are interpreted to reflect mesotrophic conditions intermittently interrupted by eutrophic shifts associated with the early Maastrichtian cooling event. The relative proportion of endobenthics increased (60%-80%) again towards the late Maastrichtian (upper part of the B. draco TRZ), showing a particular increase in EnA morphogroups prevailing in the SBF assemblages. Moreover, test morphology analyses of SBF assemblages allowed us to distinguish six epibenthic (M1 to M6) and seven endobenthic (M7 to M13) morphogroups based on their mode of coiling. This classification reveals the flourishing of EpC M4 and M5 morphogroups during the early Maastrichtian due to more oxygenated conditions on the sea floor.

Campanian carbon isotope calibrated paleofertility estimates from northwestern Tunisia: Inferences from calcareous nannofossils

Abstract The δ13C calibrated Campanian (upper part of CC17/UC13 to CC23a/UC16 zones) calcareous nannofossil assemblages were analyzed to reconstruct paleofertility, paleoenvironment, and sea–level changes from the Jebil section, north–western Tunisia. Seven globally–recognized δ13C events are noted: three positive [Santonian–Campanian Boundary Event (SCBE); Early–Campanian Event (ECE); Mid–Campanian Event (MCaE)] and four negative excursions (Pillula Event; Conica Event; Late–Campanian Event (LCE); Epsilon Event or the C1– Event). The nannofossil assemblage is dominated by Watznaueria barnesae (28%), Lucianorhabdus cayeuxii (8%), Micula decussata (6%), Cyclagelosphaera reinhardtii (5%) and Micula concava (4%). In spite of the dominance of W. barnesiae (range: 33–46.5%), the signal given by the nannofossil assemblage is primary. All species–based proxies (the percentage abundances of stressed/opportunistic taxa, high and low fertility taxa, cool and warm watermass taxa, and Nannoconus spp.) along with the inferred Paleotemperature Index, suggests a cooling trend for the Campanian. Data suggests that oligotrophy was a greater influencing factor than paleotemperature, for the observed changes within the nannofossil assemblage. As a result of this extreme oligotrophy, a distinct assemblage is recorded that is marked by the absence of Biscutum, reduced % abundances of Prediscosphaera (0.7%), Retecapsa (2.3%), and Zeugrhabdotus (1.8%), but with the dominance of W. barnesiae.

Assessment of trace metallic element contamination in sediment and water of the Bou Grine District, North-western Tunisia: concentrations, sources and environmental implications

The present investigation was conducted in the vicinities of the Bou Grine abandoned mine in order to assess the presence and the spatial distribution of trace metallic elements (TME) or trace metals in soil, surface water and groundwater. Water and sediment samples were collected and analysed to determine the principal physicochemical properties of the TME. High level contamination of soil by Pb, Zn and Cu was detected, with maximum concentrations of 14,149 mg/kg, 14,691 mg/kg and 165.7 mg/kg, respectively. These relatively high concentrations bring insight to the anthropogenic impact related to the erosion of dump deposits, which represent the principal source of metal contamination in the soil. The distribution of trace elements concentrations in water (surface or groundwater) shows that the high values, which largely exceed the World Health Organization (WHO) standards for drinking water, occur downstream the abandoned mine. This finding confirms the assumption that the abandoned mine site constitutes the main source of metal pollution, which needs its urgent rehabilitation in order to avoid the undesirable interaction with agricultural and urban areas.

Assessment of trace metallic element contamination in sediment and water of the Bou Grine District, North-western Tunisia: concentrations, sources and environmental implications

The present investigation was conducted in the vicinities of the Bou Grine abandoned mine in order to assess the presence and the spatial distribution of trace metallic elements (TME) or trace metals in soil, surface water and groundwater. Water and sediment samples were collected and analysed to determine the principal physicochemical properties of the TME. High level contamination of soil by Pb, Zn and Cu was detected, with maximum concentrations of 14,149 mg/kg, 14,691 mg/kg and 165.7 mg/kg, respectively. These relatively high concentrations bring insight to the anthropogenic impact related to the erosion of dump deposits, which represent the principal source of metal contamination in the soil. The distribution of trace elements concentrations in water (surface or groundwater) shows that the high values, which largely exceed the World Health Organization (WHO) standards for drinking water, occur downstream the abandoned mine. This finding confirms the assumption that the abandoned mine site constitutes the main source of metal pollution, which needs its urgent rehabilitation in order to avoid the undesirable interaction with agricultural and urban areas.

First report of the rare tooth fungus Hericium erinaceus in North African temperate forests

The rare fungus Hericium erinaceus (Bull.) Pers. was collected from temperate forests in northwestern Tunisia and described for the first time in Africa. In this paper, we report data about the distribution, ecology, morphology and molecular identification of H. erinaceus. Collected data may help expand our knowledge on this critically endangered rare species worldwide.

Chemical properties, antioxidant activities and in vitro fermentation profiles of some shrubs of North Western Tunisia

The main aims of this study were to analyze the chemical composition and total phenolic, and to evaluate the in vitro fermentation and antioxidant activities from some shrubs (Erica arborea, Myrtus communis, Arbutus unedo and Phillyrea latifolia). The determination of the chemical composition, total phenolic, flavonoid contents and the antioxidant activity were investigated by using in vitro methods. The in vitro gas production and ruminal parameters were determined in the presence of goat rumen juice. Total nitrogen content was significantly high with Myrtus communis (p less than 0.01). Total phenolic and flavonoid content vary by species and season (p less than 0.01). It can be concluded that all parameters were significantly affected by the seasonal period and the shrubs nature. Expect the OM that was similar regardless the seasonal period.

Effects of clay properties in the landslides genesis in flysch massif: Case study of Aïn Draham, North Western Tunisia

Heavy rainfall in Aïn Draham province in the North-Western of Tunisia lead to the formation of some landslides which could poses danger to lives and properties. The geological outcrops of the region mainly consist of Numidian flysch rocks. In this study, field based 15 undisturbed samples were taken, from 11 boreholes drilled in 4 landslide points, to understand the real behaviour of soils when landslides occur. For this purpose, the geotechnical characterization of all samples was carried out. The grain size distribution shows that the clay and silt fractions prevail. The clay fraction ranges between 4% and 64% with an average of 40.4%, the silt fraction ranging from 19% to 71% averaging 39.8% and the sand fraction was between 6% and 44% with an average of 19.8%. The Casagrande plasticity chart indicates that 33.3% of samples were in the high plasticity group (CH group) and 66.6% having a medium to low plasticity. The water content varies between 12% and 31%. The direct shear strength test shows that the cohesions values range from 41 KPa to 77 KPa and the internal friction angle values range widely from 12° to 27°. A statistical approach was taken to determine the most important factors responsible for the decrease of the cohesion and friction angle which are in charge of slope failure. For this, a correlation matrix of all soil properties was done. The coefficients of correlation show that the clay fraction is the most correlated parameter to the cohesion with an index of −0.872. Unfortunately, the internal friction angle is very low correlated to all geotechnical parameters. The clay fraction, as the most correlated to the cohesion, and the water content, which depends on rainfall (landslide triggering factor), were considered as two independent parameters for the establishment of a multiple linear and non-linear regression models of the cohesion. The multiple linear model showed that the cohesion decrease with the increase of water content and especially the increase of clay fraction with coefficients of −0.083 and −0.441, respectively. The non linear model showed that the cohesion decrease exponentially and linearly with the increase of the clay fraction and water content, respectively. The statistical study of the effect of geotechnical parameters on the landslide triggering, shows that the clay formations and also the increases of soils clay fraction by alteration phenomena is the crucial factor in landslides genesis. During rainfall the increase of the water content of clayey soils decreases the shear strength of soils more and more.

Occurrence of Septoria tritici blotch (Zymoseptoria tritici) disease on durum wheat, triticale, and bread wheat in Northern Tunisia.

Wheat (Triticum aestivum L.) is the most important cereal crop in Tunisia, nonetheless production is highly affected by drought and diseases mainly Septoria tritici blotch (STB) caused by Zymoseptoria tritici (Roberge ex Desm.) Quaedvl. & Crous anamorph and Mycosphaerella graminicola (Fuckel) J. Schrot. 1894 teleomorph; that has become an inherent disease of durum wheat (Triticum turgidum L. subsp. durum (Desf.) van Slageren) but rarely observed on bread wheat (Triticum aestivum L. subsp. aestivum) and on triticale (×Triticosecale spp.) The main objective of this work was to study the prevalence and geographical distribution of Z. tritici on triticale, durum wheat and particularly on bread wheat in different cereal growing regions of North and Northwestern Tunisia to confirm its presence/absence on bread wheat. For this study, 126 wheat fields were surveyed in North and Northwestern Tunisia during 2015-2016 and 2016-2017 cropping seasons. STB on durum wheat was present in the majority of inspected durum wheat fields, where high mean incidence (60%) and severity (40%) were recorded at Jendouba, Bizerte, Beja, and Kef. The survey data revealed low risk on bread wheat with an incidence of 23% and 29% at Bizerte and Beja, respectively. However high incidence of 84% and 52% was recorded at Cap Bon in 2016 and 2017, respectively and mainly at El Haouaria where STB severity was relatively high on bread wheat landrace of unknown origin but called by local farmers as ‘Farina arbi’. Sporadic incidence was recorded on Triticale of 100% at Jendouba (in 2016), and 33% at Bizerte (in 2016 and 2017) and absence at all other surveyed sites; likewise for severity at same locations where 13% and 42% were recorded in 2016. The survey data revealed low risk on bread wheat except at El Haouaria where STB severity was relatively high on a bread wheat landrace; while it was considered as high risk at all durum wheat fields in Beja, Bizerte, Jendouba, Zaghouan and Kef regions, such distinct occurrence could lead to clarify host specificity in Z. tritici.

Effect of thinning on Pinus pinea L. development and physico-chemical soil characteristics in northwestern Tunisia: modeling of radial growth under thinning intensity

Effect of thinning on Pinus pinea L. development and physico-chemical soil characteristics in northwestern Tunisia: modeling of radial growth under thinning intensity

Resistance development and insecticide susceptibility in Culex pipiens pipiens, an important vector of human diseases, against selection pressure of temephos and its relationship to cross-resistance towards organophosphates and pyrethroids insecticides.

Culex pipiens pipiens is an important vector of human diseases. To determine the insecticide resistance development in Culex pipiens pipiens against selection pressure of temephos.. A field population of Culex pipiens pipiens was collected from Northwestern Tunisia with a medium level of temephos resistance (LC50 = 0.0069). It was subjected to six generations of temephos pressure selection to evaluate its relationship to cross-resistance towards organophosphates (OPs) and pyrethroids (PYR) insecticides. The selection was initiated at the dose 0.0266, 0.0748 and 0.0069 which were increased during successive generations up to 0.1488, 3.8747 and 0.0086 after sixth generation for temephos, chlorpyrifos and permethrin insecticides, respectively. It is important to noted that high cross-resistance to chlorpyrifos insecticide (OP) was detected (51.88×). However, little or no cross-resistance to the pyrethroid permethrin (PYR) was recorded (1.24×). Contrary to metabolic resistance, it seemed that acetylcholinesterases AChE 1 was fixed under pressure selection. The high cross-resistance to temephos and chlorpyrifos is reasonable because they belong to the same class of insecticide (OP). However, the little cross-resistance to the pyrethroid permethrin could support its use alternately for Culex pipiens pipiens control.

An efficient knowledge-based approach for random variation interpretation in NDVI time series

Nowadays, detecting and interpreting random variation extracted from satellite image time series is a far-reaching real-world issue. A more adequate approach should be designed to deal with this challenge. In this paper, we propose an efficient knowledge-based approach for vegetation monitoring using normalized derivation vegetation index time series. First, a decomposition process is designed to separate seasonal, trend and remainder components. Then, a genetic based schema is proposed to generate association rules. The extracted knowledge is intended to interpret the remainder component extracted during the previous phase by discovering the hidden link between random variation and climate observations. For validation purpose, a database covering the regions in Northwestern Tunisia is used for a period starting from 2000 to 2012. The data have been derived from Moderate resolution Imaging Spectroradiometer and fused with ground climate data (temperature and precipitation) in the form of fuzzy association rules. The obtained results show the efficiency of the proposed approach by reducing the non-stationarity effect.

Mineralogical and geochemical criteria to identify the origin and the depositional environment of the upper Numidian babouchite siliceous rocks, northwestern Tunisia

The lower Miocene babouchite siliceous rocks from the Numidian Formation were widely deposited in the Northwestern of Tunisia, with a total thickness ranging from 20 to 50 m. The samples are principally composed of quartz and clay minerals (smectite, illite and kaolinite), with total lack of amorphous silica. The bulk chemical composition of the babouchite siliceous rocks is represented by high SiO2 (73.60–91.45%) and Al2O3 (5.78–10.55%) with negligible amounts of CaO, MgO, K2O and TiO2. The enrichment of these cherts by Mn and Cu, and the low content of the other trace elements are indicators of oxic condition in the water column. The ratio of Al/(Al + Fe + Mn) (0.65–0.87) is > 0.6 which is typical of a biogenic origin. Furthermore, the high ratios of Si/(Si + Al + Fe) justify the biogenic origin. All the analyzed samples from Babouch member fall into the non-hydrothermal sediment field of the Al-Fe-Mn diagram. Moreover, according to the environment discriminating diagrams, such as Al2O3/(100-SiO2) vs. Fe2O3/(100-SiO2), Al2O3/SiO2 vs. Fe2O3/SiO2 and Al2O3/(Al2O3+Fe2O3) vs. Fe2O3/TiO2, the babouchite siliceous rocks were deposited on a passive continental margin. The δ18O value of the chert, range from 24.9‰ to 27.9‰. The forming temperature determined by oxygen isotopic composition indicates formation at a slightly high temperature, about 65 °C.