ghanaopendata/ghanaian-research-english huggingface dataset:
Geochemistry and Sm–Nd isotopic composition of the Agou Igneous Complex (AIC) from the Pan-African orogen in southern Togo, West Africa: Geotectonic implications

Major, trace element concentrations and Nd, Sr isotopic data are reported for Neoproterozoic highpressure (HP) mafic granulites from the Agou Igneous complex (AIC), which marks the suture zone of the Pan-African Dahomeyide orogen in southwestern Togo. The main rock types consist of garnet-free and garnet-bearing metagabbronorites (GFM and GBM) that are cross cut by subordinate leucocratic to melanocratic veins and dykes of garnet-bearing microgabbroic rocks. Geochemical data suggest that the HP granulites may have preserved the geochemical imprints of their igneous protoliths. They display either cumulitic features or liquid compositions varying from primitive to evolved basalts and andesites and then to more differenciated dacitic magmas as supported by major and trace element contents. Primary basalts display LREE and LILE enriched patterns and no Eu anomaly, but are depleted in Y and Yb suggesting a slightly enriched mantle source or a weak crustal contamination. Mafic veins and dykes display REE flat patterns (LaN/YbN = 0.58–1.7) and a slightly negative Eu anomaly and PREE content ranging between 10 and 20. These features are consistent with protoliths of N- to E-MORB affinities. Mafic cumulates and andesitic basalts are characterized by various REE patterns which could be compared to those of the primary and/or the evolved basalts, probably identifying various igneous suites. The fractionated REE patterns (Ce/YbN 11.0–17.9) with slight LREE enrichment (Ce/SmN 3.1–3.8) and HREE depletion (Sm/YbN 3.6–4.8) could be induced by a garnet residue in the melt source. Neodymium isotopic data show that most mafic cumulative rocks have similar 143Nd/144Nd ratios between 0.5127 and 0.51289, corresponding to initial eNd(T) values between +2.26 and +6.33 that yielded TDM ages from 1.2 to 0.94 Ga. The mafic mesocratic vein displays 143Nd/144Nd values of 0.51227, corresponding to initial eNd(T) values of +6.87 that yielded TDM = 0.94 Ga, and constrains the minimum age. However primitive basalts samples A17 (GFM) and other mafic cumulate Ag224 (GBM) give an older depleted mantle source derivation age of 2.31 and 1.68 Ga respectively, suggesting crustal contamination by the surrounding gneissic Paleoproterozoic basement. The Nd isotopic compositions suggest that the parental magmas of the Agou Igneous Complex in southern Togo were derived from time-integrated depleted mantle source. Such geochemical features are consistent with an active continental margin environment and suggest that the AIC represents a magmatic body emplaced and cooled at the base of a continental crust above a subduction zone.

Source: UG
Geochemistry of Lower Cretaceous sediments, Inner Zone of Southwest Japan: Constraints on provenance and tectonic environment

A geochemical study was carried out on Lower Cretaceous sedimentary rocks of the Wakino Subgroup, Kenseki Formation, and Sasayama Group, distributed in the Inner Zone of Southwest Japan. The chemical characteristics of the Lower Cretaceous sediments indicate that these rocks are immature first-order sediments derived from igneous and/or meta-igneous rocks of predominantly felsic composition. The sediments from the Kenseki Formation and the Sasayama Group, however, show high Cr and Ni abundances, suggesting a significant contribution of detritus from ultramafic rocks. Weathering at the source areas was moderate. The high Th/U ratios (mostly >3.8), negative Eu anomalies (Eu/Eu(*) between 0.67 and 0.93) and Th/Sc ratios (mostly between 0.5 and 1) of the Lower Cretaceous sediments suggest their derivation dominantly from an old upper crust with minor amounts of young arc-derived detritus. The major, trace and rare earth element compositions imply that deposition took place in an active continental margin environment. The small amounts of young arc-derived material in the sediments support the inference by other workers that arc magmatism was not so prominent in Southwest Japan during the early Cretaceous.

Source: UG
Geochemistry of Paleoproterozoic metasedimentary rocks from the Birim diamondiferous field, southern Ghana: Implications for provenance and crustal evolution at the Archean-Proterozoic boundary

Metagraywackes and metapelites from the Paleoproterozoic Birimian Supergroup in the Birim diamondiferous field, southern Ghana, were analyzed for their major and trace element contents. Compared to early Proterozoic crust, the metasedimentary rocks are enriched in ferromagnesian elements but depleted in rare earth elements (REE), high field strength elements (HFSE) (with exception of Zr), and Th. They show REE patterns similar to their Archean counterparts. The chemical data indicate that the sediments were derived from a local source of mixed felsic-mafic composition, with the latter dominating. The source rocks were the basaltic to dacitic volcanic rocks and granitoids within the Birimian greenstone belts. The chemical data further suggest their deposition in a tectonic setting comparable to modern island arcs, and that minimal old upper crust (i.e., pre-Birimian sources) was involved in their formation. The analyzed metasedimentary rocks have Eu-anomalies and GdN/YbN, Sm/Nd, Th/Sc, Cr/Sc and Cr/Th ratios that closely resemble those of their Archean counterparts, and therefore inconsistent with models suggesting abrupt compositional changes in upper crust at the Archean-Proterozoic boundary. © 2004 by The Geochemical Society of Japan.

Source: UG
Geochemistry Of Podiform Chromitite And Host Rocks Within The Buem Structural Unit, Northwestern Benin Republic: Implications For The Geodynamic Evolution Of The Dahomeyide Orogenic Belt.

The paper presents the geochemistry, origin and geodynamic setting of podiform chromitite and host rocks from the Buem Structural Unit (BSU) in the northwestern Benin Republic. Qualitative Scanning Electron Microscopy (SEM), quantitative Electron probe Micro Analysis (EPMA), and whole-rock geochemical investigation have been conducted on BSU chromite and mafic-ultramafic rocks. The BSU is the westernmost unit of the Dahomeyide orogenic belt. It consists mainly of metamorphosed mafic-ultramafic rock and clastic sedimentary rocks. Chromitites units are exposed within the mafic-ultramafic rocks. Qualitative SEM analyses indicated that chromitite is mainly composed of chromite and serpentine minerals. The qualitative EPMA data shows that Cr2O3 and MnO contents (wt%) of spinel of the BSU varying from 35.91 to 44.53 and from 0.05 to 0.16, respectively and are typical primary Cr-spinel. The calculated parental composition of melts (13.71–16.67 wt% Al2O3 and FeO/MgO values in the range 0.15–0.30) from which the BSU chromitites precipitated is very similar to MORB-type magma. The chemical composition of BSU chromites and its host rocks shows that these chromites were most likely crystallized from MORB. The magma originated as a partial melt that occurred in a Mid-Ocean Ridge environment, probably during the early stage of the Pan-African orogeny at the margin of the West African Craton.

Source: UG
Geochronologic-petrochemical studies of the Hongshishan mafic-ultramafic intrusion, Beishan area, Xinjiang (NW China): Petrogenesis and tectonic implications

The Hongshishan mafic-ultramafic intrusion (SIMS zircon U-Pb age 286.4 ± 2.8Ma) consists of dunite, clinopyroxene peridotite, troctolite, and gabbro. Major elements display systematic correlations. Trace elements have identical distribution patterns, including flat rare-earth element (REE) patterns with positive Eu anomalies and enrichments in large ion lithophile elements (LILE) but depletions in Nb and Ta, indicating fractional crystallization as a key factor in magmatic evolution. Petrologic and geochemical variations in drill core samples demonstrate that minor assimilation and progressive magma injections were closely associated with Ni-Cu mineralization. Mass balance estimates and Sr-Nd isotopes reveal that the Hongshishan parental magmas were high-Mg and low-Ti tholeiitic basalts and were derived from a lithospheric mantle source that had been modified by subducted slab metasomatism before partial melting. Southward subduction of the Palaeo-Tianshan-Junggar Ocean is further constrained by a compilation of inferred, subduction-induced modifications of mantle sources in mafic-ultramafic intrusions distributed in the eastern Tianshan-Beishan area. Integrating the regional positive εNd(t) granites, high-Mg and low-Ti basaltic magmas (mafic-ultramafic intrusions), and slightly later high-Ti basalts in NW China suggests that their petrogenesis could be attributed to Permian mantle plume activities. © 2012 Copyright Taylor and Francis Group, LLC.

Source: UG
Geographic accessibility to public health facilities providing tuberculosis testing services at point-of-care in the upper east region, Ghana

Background: In Ghana, limited evidence exists about the geographical accessibility to health facilities providing tuberculosis (TB) diagnostic services to facilitate early diagnosis and treatment. Therefore, we aimed to assess the geographic accessibility to public health facilities providing TB testing services at point-of-care (POC) in the Upper East Region (UER), Ghana. Methods: We assembled detailed spatial data on all 10 health facilities providing TB testing services at POC, and landscape features influencing journeys. These data were used in a geospatial model to estimate actual distance and travel time from the residential areas of the population to health facilities providing TB testing services. Maps displaying the distance values were produced using ArcGIS Desktop v10.4. Spatial distribution of the health facilities was done using spatial autocorrelation (Global Moran’s Index) run in ArcMap 10.4.1. We also applied remote sensing through satellite imagery analysis to map out residential areas and identified locations for targeted improvement in the UER. Results: Of the 13 districts in the UER, 4 (31%) did not have any health facility providing TB testing services. In all, 10 public health facilities providing TB testing services at POC were available in the region representing an estimated population to health facility ratio of 125,000 people per facility. Majority (60%) of the health facilities providing TB testing services in the region were in districts with a total population greater than 100,000 people. Majority (62%) of the population resident in the region were located more than 10 km away from a health facility providing TB testing services. The mean distance ± standard deviation to the nearest public health facility providing TB testing services in UER was 33.2 km ± 13.5. Whilst the mean travel time using a motorized tricycle speed of 20 km/h to the nearest facility providing TB testing services in the UER was 99.6 min ± 41.6. The results of the satellite imagery analysis show that 51 additional health facilities providing TB testing services at POC are required to improve geographical accessibility. The results of the spatial autocorrelation analysis show that the spatial distribution of the health facilities was dispersed (z-score = − 2.3; p = 0.02).Conclusion: There is poor geographic accessibility to public health facilities providing TB testing services at POC in the UER of Ghana. Targeted improvement of rural PHC clinics in the UER to enable them provide TB testing services at POC is highly recommended.

Source: UG
Geographic mobility and potential bridging for sexually transmitted infections in Agbogbloshie, Ghana.

Short-term mobility can significantly influence the spread of infectious disease. In order for mobile individuals to geographically spread sexually transmitted infections (STIs), individuals must engage in sexual acts with different partners in two places within a short time. In this study, we considered the potential of mobile individuals as bridge populations - individuals who link otherwise disconnected sexual networks and contributed to ongoing STI transmission. Using monthly retrospective panel data, we examined associations between short-term mobility and sexual partner concurrency in Agbogbloshie, Ghana. We also examined bridging by the location of sex acts and the location of sexual partners in concurrent triads, and whether mobile individuals from our sample were more likely to be members of geographic bridging triads. Although reported rates of sexual partnership concurrency were much higher for men compared to women, mobility was only associated with increased concurrency for women. Additionally, this association held for middle-distance mobility and short-duration trips for women. Taking into account the location of sex acts and the location of sexual partners, about 22% of men (21.7% and 22.4% for mobile and non-mobile men, respectively) and only 3% of women (1.4% and 3.3% for mobile and non-mobile women, respectively) were potential bridges for STIs over the last year. Our results highlight the gendered nature of mobility and sexual risk behavior, reflecting the normative social context that encourages women to conceal certain types of sexual behavior.

Source: UG
Geographical access to care at birth in Ghana: a barrier to safe motherhood

Abstract Background Appropriate facility-based care at birth is a key determinant of safe motherhood but geographical access remains poor in many high burden regions. Despite its importance, geographical access is rarely audited systematically, preventing integration in national-level maternal health system assessment and planning. In this study, we develop a uniquely detailed set of spatially-linked data and a calibrated geospatial model to undertake a national-scale audit of geographical access to maternity care at birth in Ghana, a high-burden country typical of many in sub-Saharan Africa. Methods We assembled detailed spatial data on the population, health facilities, and landscape features influencing journeys. These were used in a geospatial model to estimate journey-time for all women of childbearing age (WoCBA) to their nearest health facility offering differing levels of care at birth, taking into account different transport types and availability. We calibrated the model using data on actual journeys made by women seeking care. Results We found that a third of women (34%) in Ghana live beyond the clinically significant two-hour threshold from facilities likely to offer emergency obstetric and neonatal care (EmONC) classed at the &#8216;partial&#8217; standard or better. Nearly half (45%) live that distance or further from &#8216;comprehensive&#8217; EmONC facilities, offering life-saving blood transfusion and surgery. In the most remote regions these figures rose to 63% and 81%, respectively. Poor levels of access were found in many regions that meet international targets based on facilities-per-capita ratios. Conclusions Detailed data assembly combined with geospatial modelling can provide nation-wide audits of geographical access to care at birth to support systemic maternal health planning, human resource deployment, and strategic targeting. Current international benchmarks of maternal health care provision are inadequate for these purposes because they fail to take account of the location and accessibility of services relative to the women they serve.

Source: UG
Geographical Accessibility to Glucose-6-Phosphate Dioxygenase Deficiency Point-of-Care Testing for Antenatal Care in Ghana

Background: Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency screening test is essential for malaria treatment, control, and elimination programs. G6PD deficient individuals are at high risk of severe hemolysis when given anti-malarial drugs such as primaquine, quinine, other sulphonamide-containing medicines, and chloroquine, which has recently been shown to be potent for the treatment of coronavirus disease (COVID-19). We evaluated the geographical accessibility to POC testing for G6PD deficiency in Ghana, a malaria-endemic country. Methods: We obtained the geographic information of 100 randomly sampled clinics previously included in a cross-sectional survey. We also obtained the geolocated data of all public hospitals providing G6PD deficiency testing services in the region. Using ArcGIS 10.5, we quantified geographical access to G6PD deficiency screening test and identified clinics as well as visualize locations with poor access for targeted improvement. The travel time was estimated using an assumed speed of 20 km per hour. Findings: Of the 100 clinics, 58% were Community-based Health Planning and Services facilities, and 42% were sub-district health centers. The majority (92%) were Ghana Health Service facilities, and the remaining 8% were Christian Health Association of Ghana facilities. Access to G6PD deficiency screening test was varied across the districts, and G6PD deficiency screening test was available in all eight public hospitals. This implies that the health facility-to-population ratio for G6PD deficiency testing service was approximately 1:159,210 (8/1,273,677) population. The spatial analysis quantified the current mean distance to a G6PD deficiency testing service from all locations in the region to be 34 ± 14 km, and travel time (68 ± 27 min). The estimated mean distance from a clinic to a district hospital for G6PD deficiency testing services was 15 ± 11 km, and travel time (46 ± 33 min). Conclusion: Access to POC testing for G6PD deficiency in Ghana was poor. Given the challenges associated with G6PD deficiency, it would be essential to improve access to G6PD deficiency POC testing to facilitate administration of sulphadoxine-pyrimethamine to pregnant women, full implementation of the malaria control program in Ghana, and treatment of COVID-19 patients with chloroquine in malaria-endemic countries. To enable the World Health Organization include appropriate G6PD POC diagnostic tests in its list of essential in-vitro diagnostics for use in resource-limited settings, we recommend a wider evaluation of available POC diagnostic tests for G6PD deficiency, particularly in malaria-endemic countries.

Source: UG
Geographical distribution of complement receptor type 1 variants and their associated disease risk

The main research focus of the Electron Microscopy and Histopathology Department in the past 20 years has been in the areas of enteric diarrhoeas with special emphasis on rotavirus. Through its diarrhoea surveillance studies, the Department has helped to firmly establish rotaviruses as a major cause of diarrhoea in children, and document the circulation of unusual rotavirus genotypes in Ghana. The Department has also recently expanded its diagnostic repertoire to include the identification and characterization of noroviruses, astroviruses, and other enteric viruses.

Source: UG
Geographical Distribution of Diurnal and Semidiurnal Parametric Subharmonic Instability in a Global Ocean Circulation Model

The evidence for, baroclinic energetics of, and geographic distribution of parametric subharmonic instability (PSI) arising from both diurnal and semidiurnal tides in a global ocean general circulation model is investigated using 1/12.5° and 1/25° simulations that are forced by both atmospheric analysis fields and the astronomical tidal potential. The paper examines whether PSI occurs in the model, and whether it accounts for a significant fraction of the tidal baroclinic energy loss. Using energy transfer calculations and bispectral analyses, evidence is found for PSI around the critical latitudes of the tides. The intensity of both diurnal and semidiurnal PSI in the simulations is greatest in the upper ocean, consistent with previous results from idealized simulations, and quickly drops off about 5° from the critical latitudes. The sign of energy transfer depends on location; the transfer is positive (from the tides to subharmonic waves) in some locations and negative in others. The net globally integrated energy transfer is positive in all simulations and is 0.5%–10% of the amount of energy required to close the baroclinic energy budget in the model. The net amount of energy transfer is about an order of magnitude larger in the 1/25° semidiurnal simulation than the 1/12.5° one, implying the dependence of the rate of energy transfer on model resolution.

Source: UG
Geographical inequalities and social and environmental risk factors for under-five mortality in Ghana in 2000 and 2010: Bayesian spatial analysis of census data.

Background Under-five mortality is declining in Ghana and many other countries. Very few studies have measured under-five mortality—and its social and environmental risk factors—at fine spatial resolutions, which is relevant for policy purposes. Our aim was to estimate under-five mortality and its social and environmental risk factors at the district level in Ghana. Methods and Findings We used 10% random samples of Ghana’s 2000 and 2010 National Population and Housing Censuses. We applied indirect demographic methods and a Bayesian spatial model to the information on total number of children ever born and children surviving to estimate under-five mortality (probability of dying by 5 y of age, 5q0) for each of Ghana’s 110 districts. We also used the census data to estimate the distributions of households or persons in each district in terms of fuel used for cooking, sanitation facility, drinking water source, and parental education. Median district 5q0 declined from 99 deaths per 1,000 live births in 2000 to 70 in 2010. The decline ranged from <5% in some northern districts, where 5q0 had been higher in 2000, to >40% in southern districts, where it had been lower in 2000, exacerbating existing inequalities. Primary education increased in men and women, and more households had access to improved water and sanitation and cleaner cooking fuels. Higher use of liquefied petroleum gas for cooking was associated with lower 5q0 in multivariate analysis. Conclusions Under-five mortality has declined in all of Ghana’s districts, but the cross-district inequality in mortality has increased. There is a need for additional data, including on healthcare, and additional environmental and socioeconomic measurements, to understand the reasons for the variations in mortality levels and trends.

Source: UG