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Panagiotis Tsombos, Institute of Geology and Mineral Exploration (Greece)
Konstantinos Nikolakopoulos, Institute of Geology and Mineral Exploration (Greece)
Dimitrios Mitropoulos, Institute of Geology and Mineral Exploration (Greece)
Bernhard Grasemann, University of Vienna (Austria)
Christoph Iglseder, University of Vienna (Austria)
Konstantin Petrakakis, University of Vienna (Austria)
Monica Müller, University of Vienna (Austria)
Alexander Hugh Rice, University of Vienna (Austria)
Klaus Voit, University of Vienna (Austria)
Andras Zámolyi, University of Vienna (Austria)
Erich Draganits, Vienna University of Technology (Austria)
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Greece is covered by 325 geological map sheets at a 1/50.000 scale. Field work for these maps was undertaken during the last six decades, by both Greek and other geologists. As a result of this procedure, there are still significant problems regarding the standardisation of geological terms and about where the stratigraphic and tectonic boundaries lie within Greece.
In many regions, adjacent geological maps show marked inconsistencies at their boundaries. These have arisen because the different geologists, working at different times, have interpreted their mapping with different geological and geotectonic models.
The Institute of Geological and Mineral Exploration of Greece (I.G.M.E), acting within Community Support Framework 2000-2006, has been implementing a project called "Collection, codification and documentation of geothematic information for urban and suburban areas in Greece - pilot applications". The sixth sub-project has been concerned with updating fifty 1:50,000 geological map sheets, using GIS and remote sensing techniques. Within that framework, a new geological map of KEA Island is being produced by IGME, in collaboration with the University of Vienna.
Field work on Kea, updating the previous 1972-73 work, has shown that two major geotectonic units are present on the island. An autochthonous greenschist metamorphic grade footwall and an overlying fault zone, seen as numerous minor klippen, formed during top-to-SSW extension. No hangingwall has been unequivocally identified.
The metamorphic footwall, which dominates the island, with a tectonic thickness of >380 m, has two major units:
Marbles, 0.1-30m thick, medium to very finely crystalline, mostly monomineralic, thin laminated, of a whitish, bluish or grey colour, often intensely folded and boudinaged on both small- and large-scales. This is a calcite (ultra)-mylonite. Thin quartzofeldspathic layers may occur within the marbles.
Chloritic schists with lithologically lensoid variations in quartz, carbonate, epidote, actinolite, biotite and talc. These schists predominate, except along the eastern and southern margins of the island, where marbles are very common.
The fault-rock zone comprises ultra-mylonitic calcitic marbles and dolostone breccias. The former have a white to light grey colour whilst the latter are pale buff coloured. In some instances, the dolostone breccia has been ankeritised, giving it a dark rust colour. These low-angled fault-rocks are common in the northern (Korisia-Chalara) and southern (Petroussa) parts of the island and also on hill tops in the central-SE part of the island (e.g. Agios Simeon, Kefala). Middle resolution satellite data were used for the detection and mapping of the tectonic features. Extended field work, including new geological mapping, GPS measurements and field data collection was undertaken in September 2007 and April 2008. All the collected data will be compiled and stored in the IGME integrated geographic database.
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