SEDIMENTOLOGICAL AND GEOPHYSICAL OBSERVATIONS IN THE DELTA PLAIN OF SELINOUS RIVER, ANCIENT HELIKE, NORTHERN PELOPONNESUS GREECE

Fine and coarse grained lithofacies and depositional environments were distinguished in Selinous River delta plain, from sediment cores using an Eijkelkamp percussion corer with barrel windows. The sedimentary sequence of deltaic plain deposits of Selinous River mostly consists of fine lithofacies interbedded occasionally with conglomerate facies. Fine grained lithofacies based on sediment types, structure, color, as well as contact depths and bed characteristics were interpreted as floodplain, crevasse splay, back swamp / fresh water swamp, permanent shallow fresh water lake and ephemeral fresh water lake facies. The coarse grained lithofacies consists of pebble - conglomerates and were interpreted as paleochannels. The Time-Domain Electromagnetic technique, (TEM) was applied in order to define the spatial distribution of lenses of conglomerates, palaeochannels and fine grained sedimentary material to be recognised, at a depth up to 35m. Both the sedimentological and geophysical approaches, in combination with the available geological and geomorphological data of the area, can provide information about the evolution, existence and the geometry of paleochannels of the Selinous River flood plain, and the paleoenvironment of the area of the ancient Helike

Geophysical and geochemical study of geropotamos aquifer in the north-central coast of crete

The geological setting of Geropotamos aquifer on the north-central coast of Crete, Greece, is considered complex, while the local tectonic regime of the study area is characterized by two sets of faults orientated NW-SE and NE-SW. Investigation of the aquifer using the Transient ElectroMagnetic method (TEM) has resulted initially in 1D models of geoelectric structures and a final 3D geoelectrical model was constructed, depicting the zones of salination of groundwater in the aquifer. Groundwater samples were analysed and the most important chemical parameters were determined to provide an independent dataset for comparison with the TEM results, while Groundwater Quality Maps were produced. TEM and geochemical data correspond and provide verification of the TEM approach. As a result, saline intrusion is likely to occur along fractures in a fault zone through bedrock, and this work emphasises the critical role of fracture pathways in salination problems of coastal aquifers

Environmental geophysics: Techniques, advantages and limitations

The rapid development of industrial and urban areas in the last decades caused a significant amount of environmental degradation with serious consequences to human life, ecosystems, natural resources, land utilization, as well as to human and natural heritage. Thus, the role of site restoration and rehabilitation projects, in the context of the Management Environmental degradation, is crucial for the modern society. Environmental Geophysics comprises a relative modern part of the Geophysics discipline, aimed at determining the physical properties of the shallow sub-surface by using non invasive high-resolution geophysical techniques. The detailed knowledge of the subsurface structure is valuable for a variety of disciplines involved in the study of the shallow earth’s crust, which is directly related with human activities. In particular, Environmental Geophysics efficiently deals with technical problems arising during construction works such as karst collapse, evaporite sinkholes, landslides, mine subsidence and fault zones. Furthermore, it is involved in investigations concerning the detection of buried or abandoned waste, the location of the aquifer and part of its related properties to identify the possible presence of contaminants in the subsurface and finally, the mapping of archaeological sites. The aim of this work is to present the most familiar and robust techniques used in environmental geophysics and new methodologies of data processing and interpretation. Extensive literature research and examples from case studies are presented and analyzed. Special emphasis is given to the limitations of all applied techniques