At the Lavrion mine, area, near the village of Kamariza, an oxidized mineralization unusually rich in bismuth, gold, antimony and copper has been studied. Three different parageneses have been recognized and described: a) a copper-rich assemblage, containing chalcopyrite, chalcocine, digenite, covelline, azurite, malachite and georgeite, b) a bismuth-gold-rich assemblage, consisting of native bismuth, bismuthinite, native gold, bismite, bismutite, beyerite, kettnerite, preisingerite, rooseveltite and mixité and c) an antimony-rich one, comprising stibiconite, bindheimite, mimetite and gartrellite. The mineral study suggests that the primary mineralization should consist of pyrite ± arsenopyrite, chalcopyrite, bismuthinite (and/or bismuth sulphosalts), native bismuth, maldonite (which has been exsoluted to gold and bismuth) and bournonite. The oxidation of this primary mineralization and the reac ion with supergene solutions containing significant amounts of HCO3" and HAsCV2 - H2ASO4", caused the formation of 17 secondary minerals.
The porphyry Cu-Mo mineralizations at Kassiteres and Pagoni Rachi are genetically related with dioritic to dacitoandesitic subvolcanic rocks that were and preliminary microthermometric data indicate that the hypogene mineralizations were introduced during albitic / potassic alteration of the intrusives and temperatures about 400°C from boiling magmatic-hydrothermal fluids. Electron microprobe major element analyses are presented for magmatic and hydrothermal biotites and amphiboles from both occurences. Hydrothermal biotites in the albitic / potassic zones are more magnesian than their magmatic counterparts and therefore close to phlohopite end - member composition. The amphiboles from Kassiteres range from magnesio - hornblende to actinolite, commonly within the same grain. Moreover the chemical data in both magmatic and hydrothermal biotites and amphiboles from the above two occurences indicate a Mg - and Si - enrichment and a Ti - depletion during crustallization and cooling from magmatic to late magmatic - early hydrothermal conditions. It is likely that an increase in oxyzen fugacity accompanied their chemical evolution. This oxidation trend is associated with the fluid exsolution of the magmas resulting in the development of the studied porphyry type mineralizations. Elements, which are also depleted from Mg - rich (more oxidized) amphiboles and biotites (K, Na, Fe and Ti) are partitioned in the magmatic - hydrothermal fluid phase and are responsible for the albitic / potassic altaration of both occurences.
A new skarn, near Therapio village, in the Evros prefecture, is described in terms of mineralogy and petrogenesis. The skarn is developed in amphibolites in close relation with pegmatite veins. It is constituted of garnet, magnetite and quartz, while retrograde minerals are actinolite, and chlorite, along with sulfides and hematite, some of them also found in the host rock. The mode of skarn growth and its close relation with the pegmatite veins indicate the genetic relation between them. At the same time, the cataclastic structure of the garnets and the magnetite as well as the brittle structures, imply later tectonism. According to the field observations and the results of the laboratory study, the Therapio skarn is a result of the metasomatism due to the intrusion of the pegmatite veins into the protolite amphibolite.
Idiomorphic quartz crystals, up to 50 cm long, have been developed on massive, milky quartz substrate, within veins hosted by orthogneisses of the polymetamorphic system of the Pentelikon Mt. The veins fill NE-SW or/and NW-SE trending en-echelon fissures associated with the DfP deformation phase of Alpine age. Quartz-hosted fluid inclusions have been studied in order to decipher the physicochemical conditions of deposition and the relationship to the geotectonic evolution of the area. Homogenization temperatures (Th) to the liquid phase range between 175 and 240 °C clustering at 180-200 °C. Final ice melting temperatures (Tmjce) range between -0.1 and -14.5 °C corresponding to salinities between 0.2 and 23 wt% NaCI equiv. in the system HìO-NaCI. Thsalinity relationships indicate quartz crystallization under boiling conditions at temperatures 150-220 °C and pressures <1.5 Kbar. The results of this study indicate that quartz was deposited from hydrothermal fluids with a meteoric water component in the latest stages of retrograde metamorphism and regional decompressive uplift of the Pentelicon Mt metamorphic complex
Significant changes in the groundwater radon concentration, were observed on the 29/7/2003, at Kammena Vourla. The radon concentration changes can be attributed to the temporary enrichment of the groundwater by radon from the surrounding rocks due to the action of stress release or stress accumulation prior an earthquake. EPPO was immediately informed for the existence of these changes. On the 3/8/2003, a significant number of earthquakes in Northern Evia were recorded in an interval of a few hours. The epicentres of the earthquakes were located in the conceivable line between the epicentre of the strong earthquake of Skyros island (July 2001) and the site of the station of radon measurement at Kammena Vourla, on the extension of the Northern Aegean fault. In the 23/1/2003, in the same station, 3 significant changes of radon concentration were measured EPPO was immediately informed for impending seismic activity in Northern Evia. On the 29th of January three earthquakes were recorded. Their epicentres were located in N. Evia, close to the radon measurement, station. On the 2/2/2003, a new significant radon change occurred at Kammena Vourla followed by an earthquake (7/2/2003). In the 12/2/2003 in a letter that we addressed to the EPPO administration, the beginning of a new radon change was reported which also led to an earthquake with the same epicentre. The changes that are recorded in the system of radon measurement of Kammena Vourla are precursors of earthquakes, related to the extension of the N. Aegean fault towards the Sterea Hellas and have their epicentre in N. Evia. It seems that the method can be an important tool for local, short term earthquake prediction.
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