Structural framework and deformation episodes in the igarra schist belt, southwestern nigeria

The structural framework of the Igarra schist belt consists of brittle (mainly fractures) and ductile (foliation, cleavage, folds, lineations, strain markers) structures. The geometry of these structures reveals two major occurrences of transpressional deformation affected the schist belt. These are an older dominantly ductile deformation with NW–SE λ1 which developed foliations, cleavage, folds, and mineral/stretching lineations deforming only the metasediments and a younger brittle–ductile, E-W tectonic shortening deformation which closed deformations in the Igarra schist belt, deforming both the metasediments and granitoids, producing almost all the brittle structures in the belt. Minor fracture trends which are not associated with any of the major episodes of deformation and E-W transposition foliation in marble and gneisses constitute a relic of an unconfirmed possibly older episode of deformation. Ductile and semi-brittle shear zones in the Igarra schist belt are few and usually occur on small scale (outcrop scale), hence, they do not constitute a major episode of deformation. Mineralizations in the Igarra schist belt are pegmatite and quartz which are emplaced mainly in fractures with industrial minerals like marbles

Pyrolytic and provenance evaluation of organic matter from the tertiary niger delta basin, nigeria: implication on hydrocarbon generation.

The present work deals with evaluation of organic matter based on detailed Rock-Eval pyrolysis techniques studies to evaluate hydrocarbon generation potential of source rocks by collecting twenty- nine shale samples from well cuttings in the Tertiary Formations of the Niger Delta, Nigeria. The values of vitrinite reflectance (0.57–0.74%Ro) and maximum (Tmax: 420–445°C) confirmed that samples are at early maturity to matured stage enough to generate liquid and gaseous hydrocarbon. The cross-plot between hydrogen index (HI) and oxygen index (OI) atomic ratio indicates that samples were predominant in the bituminous rank and having kerogen Type III makes it suitable for hydrocarbon generation. Rock-Eval pyrolysis analysis (Types II-III and Type III kerogen) on shale samples from the Niger Delta reveals organic matter of predominantly terrestrial origin based on type III kerogen. The organic matter (OM) assemblages suggests a marine setting but dominated by terrestrial inputs likely related to fluvial processes which is function of most delta system. Based on high total organic carbon (TOC) value of 5.42wt% and Type III kerogen made the shale an excellent source rock, with gas-prone kerogen. The high OI, low total sulphur (TS) suggests terrestrially derived OM and deposition in an oxic and dysoxic shallow marine environment. In addition, HI and Tmax values describe the samples as a characteristic Type III dominant kerogen and potential to generate oil and gases while the Tmax, consistently indicate an immature to mature on the shale organic matter

REFUGEE INFLUX: A SOCIOLOGICAL INSIGHT AND EMPIRICAL ANALYSIS OF ITS CONCOMITANT EFFECT ON FOOD SECURITY IN ETUNG CROSS RIVER STATE, NIGERIA

The study examines the impact of Cameroun refugee influx and its impact on food security in Etung Local Government Area of Cross River State, Nigeria. The study adopted the survey research method in eliciting information from 400 samples from two political wards in Etung Local Government Area of Cross River State, Nigeria, using the purposive and random sampling technique. a self-administered structured questionnaire was the instrument of Data collection. Data gathered from the field was meticulously collated, coded and analyzed using simple percentages, frequency distribution, figures and simple lineal regression at 0.05 confidence level. Result revealed that there is a significant relationship between refugee influx and Food Security in Etung Local Government Area of Cross River State, Nigeria. The study recommends That the Cross-River state synergizes with the relevant agencies of the Federal Government as well as other international Agencies to stimulate production in Etung through agricultural programs such as farmers smallholders schemes, cassava, banana, yam, plantain plantations schemes, animal husbandry, cottage industries etc. to promote aggressive food revolution within affected areas to avert serious food crisis amongst others.  Article visualizations

Research Article. A new gravity laboratory in Ny-Ålesund, Svalbard

The Norwegian Mapping Authority (NMA) has recently established a new gravity laboratory in Ny-Ålesund at Svalbard, Norway. The laboratory consists of three independent pillars and is part of the geodetic core station that is presently under construction at Brandal, approximately 1.5 km north of NMA’s old station. In anticipation of future use of the new gravity laboratory, we present benchmark gravity values, gravity gradients, and final coordinates of all new pillars. Test measurements indicate a higher noise level at Brandal compared to the old station. The increased noise level is attributed to higher sensitivity to wind.We have also investigated possible consequences of moving to Brandal when it comes to the gravitational signal of present-day ice mass changes and ocean tide loading. Plausible models representing ice mass changes at the Svalbard archipelago indicate that the gravitational signal at Brandal may differ from that at the old site with a size detectable with modern gravimeters. Users of gravity data from Ny-Ålesund should, therefore, be cautious if future observations from the new observatory are used to extend the existing gravity record. Due to its lower elevation, Brandal is significantly less sensitive to gravitational ocean tide loading. In the future, Brandal will be the prime site for gravimetry in Ny-Ålesund. This ensures gravity measurements collocated with space geodetic techniques like VLBI, SLR, and GNSS

Combining altimetric/gravimetric and ocean model mean dynamic topography models in the GOCINA region

Initially, existing mean dynamic topography (MDT) models were collected and reviewed. The models were corrected for the differences in averaging period using the annual anomalies computed from satellite altimetry. Then a composite MDT was derived as the mean value in each grid node together with a standard deviation to represent its error. A new synthetic MDT was obtained from the new mean sea surface (MSS) KMS04 combined with a regional geoid updated using GRACE gravity and gravimetric data from a recent airborne survey. Compared with the composite MDT the synthetic MDT showed very similar results. Then combination methods were tested for the computation of MDT models from gravity data and MSS data. Both a rigorous and an iterative combination method have been tested in the GOCINA region. At this stage, the iterative combination method with its efficient handling of large data sets covering the whole region appears to give the best solution. Naturally, the errors associated with the MDT can be obtained using the rigorous method onl

Blast wave mitigation by dry aqueous foams

International audienceThis paper presents results of experiments and numerical modeling on the mitigation of blast waves using dry aqueous foams. The multiphase formalism is used to model the dry aqueous foam as a dense non-equilibrium two-phase medium as well as its interaction with the high explosion detonation products. New experiments have been performed to study the mass scaling effects. The experimental as well as the numerical results, which are in good agreement , show that more than an order of magnitude reduction in the peak overpressure ratio can be achieved. The positive impulse reduction is less marked than the overpressures. The Hopkinson scaling is also found to hold particularly at larger scales for these two blast parameters. Furthermore, momentum and heat transfers, which have the main dominant role in the mitigation process, are shown to modify significantly the classical blast wave profile and thereafter to disperse the energy from the peak overpressure due to the induced relaxation zone. In addition, the velocity of the fireball, which acts as a piston on its environment, is smaller than in air. Moreover , the greater inertia of the liquid phase tends to project the aqueous foam far from the fireball. The created gap tempers the amplitude of the transmitted shock wave to the aqueous foam. As a consequence, this results in a lowering of blast Communicated by O. Igra. wave parameters of the two-phase spherical decaying shock wave