P-T conditions of Pan-African orogeny in southeastern Nigeria

Abstract Different rock types from the area northeast of Obudu, southeastern Nigeria were investigated in order to place constraints on their metamorphic conditions. Detailed petrographic studies indicate four main rock groups in the studied area, namely migmatitic gneiss, migmatitic schist, granite gneiss and a minor amount of amphibolite, metagabbro and dolerite. The chemistry of minerals in these rocks is used to estimate metamorphic pressure and temperature (P-T) using appropriate geothermometers and geobarometers. The estimated temperature for migmatitic gneiss of the area is ∼600–625 °C and 600–650 °C for migmatitic schist; the pressure is ∼ 8 kbar. For amphibolite the temperature is ∼600–700 °C and pressure is 8–12 kbar. The estimated pressures and temperatures for the northeast Obudu rocks correspond to upper amphibolite to lower granulite facies metamorphism. The metamorphism occurred due to continent-continent collision during the Pan-African orogeny, most likely during the D1 deformational phase of the area. The recorded high pressures possibly resulted from crustal thickening in the area. P-T conditions for Pan-African orogeny in northeast Obudu area are in good agreement with P-T estimations for the Pan-African event in adjacent areas

Rare Earth Element Geochemistry And Protoliths Of Schists In Southeast Lokoja, Central Nigeria

The Nigerian schist belts constitute the most important lithologic units necessary for the unravelling of the geochemical and geodynamic evolution of the basement complex. The schists have however undergone extensive alterations owing to weathering and metamorphism. REE abundance and distribution patterns of Lokoja schists indicate that the schist belts are metamorphosed shale-greywacke sequence. Their provenance possibly contained volcanogenic debris and the passive margin of the West African craton provided most of the materials. The reworking and metamorphism of the sediments took place during the Pan-African Orogeny ca. 687 Ma ago. KEY WORDS: Schists, Provenance, Reworking, Rare Earth Element, Evolution Global Journal of Geological Sciences Vol.3(1) 2005: 9-1

Preliminary investigation of pegmatites in Obudu Area, Southeastern Nigeria, using stream sediments geochemistry

Stream sediments of Obudu Plateau were investigated with a view to elucidating their geochemical features, mineralization potentials and element concentrations. Stream sediment samples were collected from Southern Obudu Plateau area and analyzed for 22 elements, comprising major and trace elements, using Inductively Coupled Plasma – Mass Spectrometry (ICP-MS). The data obtained were statistically treated. Ba, Sr, Nb, Co, Pb, Ta and Na show moderate to high concentrations, when compared with threshold values of these elements. The concentrations of these elements in sediments of Southern Obudu show low mineralization potentials of pegmatites of the Obudu Plateau. The elements in Obudu stream sediments show perfect, strong, moderate and weak correlations among themselves, indicative of variations in their mobility.Keywords: Correlation matrix, Major and Trace Elements, Stream sediments, Threshol

Adaptation of the Wound Healing Questionnaire universal-reporter outcome measure for use in global surgery trials (TALON-1 study): mixed-methods study and Rasch analysis

BackgroundThe Bluebelle Wound Healing Questionnaire (WHQ) is a universal-reporter outcome measure developed in the UK for remote detection of surgical-site infection after abdominal surgery. This study aimed to explore cross-cultural equivalence, acceptability, and content validity of the WHQ for use across low- and middle-income countries, and to make recommendations for its adaptation.MethodsThis was a mixed-methods study within a trial (SWAT) embedded in an international randomized trial, conducted according to best practice guidelines, and co-produced with community and patient partners (TALON-1). Structured interviews and focus groups were used to gather data regarding cross-cultural, cross-contextual equivalence of the individual items and scale, and conduct a translatability assessment. Translation was completed into five languages in accordance with Mapi recommendations. Next, data from a prospective cohort (SWAT) were interpreted using Rasch analysis to explore scaling and measurement properties of the WHQ. Finally, qualitative and quantitative data were triangulated using a modified, exploratory, instrumental design model.ResultsIn the qualitative phase, 10 structured interviews and six focus groups took place with a total of 47 investigators across six countries. Themes related to comprehension, response mapping, retrieval, and judgement were identified with rich cross-cultural insights. In the quantitative phase, an exploratory Rasch model was fitted to data from 537 patients (369 excluding extremes). Owing to the number of extreme (floor) values, the overall level of power was low. The single WHQ scale satisfied tests of unidimensionality, indicating validity of the ordinal total WHQ score. There was significant overall model misfit of five items (5, 9, 14, 15, 16) and local dependency in 11 item pairs. The person separation index was estimated as 0.48 suggesting weak discrimination between classes, whereas Cronbach's α was high at 0.86. Triangulation of qualitative data with the Rasch analysis supported recommendations for cross-cultural adaptation of the WHQ items 1 (redness), 3 (clear fluid), 7 (deep wound opening), 10 (pain), 11 (fever), 15 (antibiotics), 16 (debridement), 18 (drainage), and 19 (reoperation). Changes to three item response categories (1, not at all; 2, a little; 3, a lot) were adopted for symptom items 1 to 10, and two categories (0, no; 1, yes) for item 11 (fever).ConclusionThis study made recommendations for cross-cultural adaptation of the WHQ for use in global surgical research and practice, using co-produced mixed-methods data from three continents. Translations are now available for implementation into remote wound assessment pathways