Results of hydrological and geological investigations in Benin

Focus of this study is the analysis of a local hydrogeological system in the subhumid outer tropics in the western African country of Benin. The aim was to characterize, qualify and quantify the hydrogeological and hydrological properties of the approx. 30 km2 big study area and to develop a conceptual hydrogeological model. This model should provide the basis for further studies on a regional scale. The main goal was to obtain the process knowledge of the hydrogeological system and to determine the process and the quantity of the groundwater recharge in the working area. According to the objectives, a broad hydrogeological approach was chosen. In a spacious network on the local scale TDR probes, suction cups and groundwater observation bores were installed. Also in a multidisciplinary cooperation with hydrology, geography, soil science, biology, meteorology and plant nutrition sciences, instruments like discharge gauging stations, tensiometers, lysimeter, climate stations, runoff plots and erosion pins were installed in the test site for the investigation of the relevant parameters of the hydrological cycle.

Composition of alkali picrites from the southwestern Greenland continental margin

The Labrador Sea is a basin with oceanic crust in its deep part. Bottom morphology of the Labrador Sea is rather complicated. Data of seismic profiling in this region indicate presence of numerous submarine mountains and hills, which are dominated by volcanic rocks. Some chemical and mineral characteristics of the rocks, in particular, high concentrations of alkalis and phosphorus, and presence of high-titanium augite, ilmenite, and devitrified glass enriched in K and Na, allow us to attribute them to K-Na subalkaline picrites typical for ocean islands, seamounts, and oceanic plateaus. Rocks of the K-Na subalkaline series usually form submarine basements and subaerial volcanoes of ocean islands, seamounts, and oceanic plateaus. Thus, the suggestion on formation of the highs on the continental crust is not confirmed by petrographic data, which require a refinement of the tectonic model of the northern part of the Labrador Sea.