Geochemical exploration studies in the Lavrion (laurium) area of greece.
thesisposted on 19.11.2015, 09:05 by Constantine. Fotakis-Tsipouras
Detailed geochemical studies of the dispersion patterns of selected elements (Cu, Pb, Zn, Ag, Mn, As, Fe, Ni, Co) were undertaken in the drainage sediments and soils in the Lavrion peninsula with the objective of demonstrating the application of geochemical techniques to the search for previously unknown mineral deposits. The study area comprises three geological units; the Anavissos, Kamareza and Plaka, each with its distinct stratigraphy and structural history. The Kamareza and Anavissos units are separated by the Legraina fault, while the overlying Plaka unit is separated from these underlying two units by an unconformity. Both geological and geochemical data indicate that karstic mixed sulphide mineralization is largely restricted in the Kamareza and Plaka units. An area of approximately 65 square kilometres was chosen for detailed stream sediment, soil, rock and bigeochemical studies. Digestion of 0.2 gms. Of minus 80-mesh material in 25% (HNO3 at 90C for 4 hours appeared to provide the optimum technique for dissolution of elements such as Cu, Pb, Zn, Mn, Fe and Ni. Analysis was performed by AAS for all these elements. Arsenic was also determined by the cold extraction method (James, 1957). The data obtained were treated by graphical, univariate and multivariate statistical techniques including histograms, bar-diagrams, graphs, frequency distribution analysis, moving averages, correlation coefficient, factor and regression analysis. Other properties including pH, conductivity, organic matter content and CaCO3, and both Fe-and Mn-oxide concentrations, were also investigated in order to establish their influence on the distribution patters of the various elements. It was demonstrated that within the study area mechanical dispersion dominates over chemical. In spite of contamination from extensive past mining activity, geochemical stream and soil surveys produce reliable distribution patterns in the Mediterranean environment of Lavrion. The occurrence of previously unknown mineralization was proven by trenching in target areas indicated by geochemical patterns. Biochemical surveys were also found to yield useful information, although they are time consuming and suffer from problems associated with the uneven distribution of plant species.