Igneous intrusions exercise great influence on the geodynamics of the remobilized belts, and the study of the chemical characteristics of the intrusions provides valuable information on the geotectonic development of the area. The Bansara area is underlain by the Pan-African high-grade metagreywacke-pelite sequence, metagranites and post-Pan-African rift-generated enderbites, adamellites and granites. In the paper, "Trace and Rare Earth Element Geochemical Fingerprints on the Petrogenesis and Geotectonics of the Enderbite-Adamellite-Granite Complex in Parts of Bansara (Sheet 304 NE and SE), Southeastern Nigeria", the authors, Egesi N and Ukaegbu V U, have analyzed the geochemical data of a set of igneous rock samples from parts of Bemenda Massif of Southeastern Nigeria and evaluated their petrogenetic and geotectonic features. The analysis suggests that the upper mantle derivation of the enderbites of the Bansara area is consistent with the view that most of the late-stage Pan-African magmas are mantle derived, whereas the progressive enrichment of the granites in LREE, which is normal and in the pattern of HREE with negative Eu anomaly, the adamellites and granites, may have formed by partial melting. The authors conclude that the granites and adamellites probably formed at the crustal level from the differentiating enderbitic melt of mantle origin in a setting dominated by rifting and post-collision uplift, probably due to mantle plume and mantle-crust mingling that characterized the geothermal history of the area in the post-Pan-African.

The stratigraphic sequence and analysis of major and minor facies cycle provide information regarding environments of deposition of the sedimentary sequence in a region. Sitakund hill range in Bangladesh is one of the most prominent structures situated in Bengal foredeep of the Bengal basin, and the studies on the stratigraphy of the Surma group of rocks in the region are essential for an effective exploration and exploitation of gas from the group. In the paper, "Sequence Stratigraphy of the Surma Group, Sitakund Anticline, Chittagong, Bangladesh", the authors, Mrinal Kanti Roy, Md. Moniruzzaman, Md. Masidul Haque, Partha Jit Roy, Sudip Saha and Md. Azizul Alam, have carried out a detailed study to delineate various lithounits sequentially. Their study identifies eleven facies with lithosuccession of the Surma group and recognizes genetically related five parasequence sets. The study infers that the tidal processes were the dominant driving force during the deposition, and based on the repetitive nature of the facies associations, the Boka Bil formation is interpreted to be a succession of deltaic and marginal marine tidal sediments of estuary, tidal creeks and tidal flats.

Earthquakes cannot be prevented in the earthquake-prone areas, but the damages due to an impending earthquake could be reduced considerably with the knowledge of the historical seismicity in a region. In recent times, one of the worst earthquake disasters in Africa was the 1960 Morocco earthquake, where more than 15,000 people were killed by an earthquake of only moderate magnitude5.7. Several researchers have analyzed the earthquake data of the region. In the paper, "An Analysis of Earthquake Focal Depths in Africa (1900-2000)", the authors, Ugwu Sylvester A and Onuoha K Mosto, have analyzed the depth-wise distribution of earthquakes in different regions of the continent during the last century. Among all the regions studied, they infer two types of earthquake return periods in Ethiopia55 and 32 years.

Exploration and exploitation of various rock types, such as granites, marbles and sand stones, for use in the construction industry have attracted the attention of business sector due to the aesthetic beauty of these rocks. The selection of a suitable rock type depends on the mineralogical, chemical, physical and mechanical properties. In the paper, "Evaluation of Physicomechanical Properties of Granites in Warangal District, AP, as Dimensional and Decorative Stones", the authors, G Prabhakar, Ishrath and A P Siva Kumar, have analyzed the suitability of various rock types for the purpose, based on a study of physicomechanical parameters of a suite of granites.

The physical and geological characteristics of groundwater aquifers are greatly influenced by various parameters, including land-use activities. In the paper, "Environmental Control of Groundwater Resources in Siliguri Subdivision of Darjeeling District, India", the authors, Khondoker Emamul Haque and M M Jana, have evaluated the influence of various parameters on the physicochemical characteristics of groundwater resources from different lithological units in the Siliguri subdivision of Darjeeling district. Soil erosion, deforestation and climate were found to be contributing to the low concentration of chemical constituents such as Ca, Mg and F ions, whereas the presence of iron ore deposits is the principal reason for the maximum concentration of Fe in the groundwater. The study suggests afforestation of the shifting cultivated areas and management of the existing forests, which decrease rapid soil erosion and water runoff, as long-term measures to increase the concentration of chemical constituents in the groundwater.

Attempts to establish fish ponds in the prohibited area (till the fifth contour) of Kolleru freshwater lake in Andhra Pradesh are an ongoing problem ever since the Government of Andhra Pradesh declared the area as a wildlife sanctuary in 1999. The constant monitoring of the area and getting rid of unauthorized setting up of fish ponds can be effectively done by remote sensing and GIS. In this backdrop, the paper, "CBD 2010 Target: A Case Study of Kolleru Wetland (Ramsar Site), India Using Remote Sensing and GIS", by the authors, Chiranjibi Pattanaik, S Narendra Prasad, Nidhi Nagabhatla and S S Sellamuttu, has demonstrated the use of remote sensing and GIS for effective Land Use Land Cover (LULC) and for generating baseline information.

-- S V Srirama Rao,
Consulting Editor