The north cycladic detachment system and associated mineralization, Mykonos, Greece: Insights on the evolution of the Aegean domain

International audienceIn the Aegean back-arc domain, some 30-35 Ma ago, an increase of the rate of slab retreat led to the initiation of post-orogenic extension, largely accommodated by large-scale structures such as the North Cycladic Detachment System (NCDS). Although this extension is still active nowadays, an E-W compressional regime developed in the Late Miocene with the propagation of the North Anatolian Fault. On Mykonos island (Cyclades), the NE-SW back-arc extension is particularly well expressed with the Livada and Mykonos detachments that belong to the NCDS and that are associated with NW-SE barite veins emplaced during the synkinematic cooling of the Mykonos intrusion. This study shows that the formation of the mineralization occurred when the pluton crossed the ductile-to-brittle transition during its exhumation below the NCDS at ~11-10 Ma. In addition, the kinematics of mineralized structures evolved with time: (1) most of the displacement was accommodated by the top-to-the-NE Livada and Mykonos detachments accompanied by the formation of mineralized normal faults that were (2) reworked in a strike-slip regime with an E-W direction of shortening and a persistent NE-SW stretching and (3) a latepost-mineralization E-W compressional stage with a minor reworking of shallow-dipping faults (locally including the detachments themselves). We interpret this increase of the E-W shortening component recorded during the mineraldeposition as a consequence of the initiation of the westward motion of Anatolia from 10 Ma, thus 4 Ma before the propagation of the North Anatolian Fault in the Dardanelles Strait and the localization of the strain on the Aegean Sea margins

METALLOGENY OF MASSIVE SULFIDES AND PETROLOGY OF THE EXTERNAL METAMORPHIC BELT OF THE HELLENIDES (S.E. PELOPONNESUS)

CONSIDERATION OF THE GEOLOGICAL, MINERALOGICAL, GEOCHEMICAL AND STRATIGRAPHIC CHARACTERISTICS OF THE STUDIED SEGMENT OF THE EXTERNAL METAMORPHIC BELT OF THEHELLENIDES IN SE PELOPONNESUS, LEAD TO THE FOLLOWING CONCLUSIONS: 1. THE ROCKS OF THE "TYROS BEDS" HAVE SUFFERED A VERY LOW GRADE METAMORPHISM. THE TEMPERATURE OF METAMORPHISM IS ESTIMATED TO HAVE BEEN ABOUT 320-350 C AND THE PRESSURE ABOUT 2 KB. 2. THE VOLCANIC ROCKS OF THE "TYROS BEDS" ARE CALC-ALKALINE AND RANGE FROM BASALTIC ANDESITES TO ANDESITES. THEY ARE PRODUCTS OF VOLCANISM CLOSELY RELATED TO A SUBDUCTION ZONE. THE PYROCLASTICS ARE WIDESPEAD WHEREAS THELAVAS-OFTEN PORPHYRITIC-ARE NOT. 3. THE VOLCANIC ROCKS OF THE "TYROS BEDS" WERE HYDROTHERMALLY ALTERED DURING THE VOLCANISM. THIS ALTERATION WAS SIMILAR TOTHAT OF HYDROTHERMAL TERRAINS AT SITES OF SUBMARINE VOLCANISM, WHICH IS A RESULT OF THE INTERACTION BETWEEN SEA WATER AND VOLCANIC ROCK. 4. THE ORE OCCURRENCES IN THE STUDIED AREA, HOSTED IN THE "TYROS BEDS", CAN BE DIVIDED ACCORDINGTO THEIR MINERALOGY, MODE OF OCCURRENCE AND TYPE OF ENVELOPING ROCKS INTO TWOMAIN GROUPS: THE FIRST GROUP INCLUDES PB-ZN-FE-CU SULFIDE ASSEMBLAGES IN VOLCANIC ROCKS AND IS CONSIDERED TO BE OF EPIGENETIC ORIGIN. THE SECOND GROUP INCLUDES GALENA AND BARITE IN CARBONATE ROCKS. THE FIRST GROUP CAN BE FURTHER SUBDIVIDED INTO TWO MORPHOLOGICAL TYPES: THE FIRST INCLUDES DISSEMINATED CU WITH MINOR FE SULFIDE ASSEMBLAGES IN PORPHYRITIC VOLCANIC ROCKS, WHEREAS THE SECONDTYPE INCLUDES PB-ZN-FE- CU SULFIDE ASSEMBLAGES IN STOCKWORK FORM SPATIALLY RELATED TO QUARTZ- CHLORITE-SERICITE ALTERED BRECCIAS. (SHORTENED)ΤΑ ΚΥΡΙΑ ΣΥΜΠΕΡΑΣΜΑΤΑ, ΠΟΥ ΠΡΟΕΚΥΨΑΝ ΑΠΟ ΤΗΝ ΠΕΤΡΟΛΟΓΙΚΗ ΚΑΙ ΜΕΤΑΛΛΟΓΕΝΕΤΙΚΗ ΜΕΛΕΤΗ ΣΕ ΤΜΗΜΑ ΤΗΣ ΕΞΩΤΕΡΙΚΗΣ ΜΕΤΑΜΟΡΦΙΚΗΣ ΖΩΝΗΣ ΤΩΝ ΕΛΛΗΝΙΔΩΝ ΣΤΗΝ ΝΑ ΠΕΛΟΠΟΝΝΗΣΟ, ΣΥΝΟΨΙΖΟΝΤΑΙ ΣΤΑ ΕΞΗΣ: 1. ΤΑ "ΣΤΡΩΜΑΤΑ ΤΥΡΟΥ" ΠΟΥ ΘΕΩΡΟΥΝΤΑΙ ΥΠΟΒΑΘΡΟ ΤΗΣ ΕΝΟΤΗΤΑΣ ΤΡΙΠΟΛΕΩΣ, ΕΧΟΥΝ ΥΠΟΣΤΕΙ ΓΕΝΙΚΗ ΜΕΤΑΜΟΡΦΩΣΗ ΠΟΛΥ ΧΑΜΗΛΟΥ ΒΑΘΜΟΥ (VERY LOW GRADE). Η ΘΕΡΜΟΚΡΑΣΙΑ ΜΕΤΑΜΟΡΦΩΣΗΣ ΕΚΤΙΜΑΤΑΙ ΟΤΙ ΗΤΑΝ ΠΕΡΙ ΤΟΥΣ 320-350C ΚΑΙ Η ΠΙΕΣΗ ΠΕΡΙ ΤΑ 2 KB. 2. ΟΙ ΗΦΑΙΣΤΙΤΕΣ ΤΩΝ "ΣΤΡΩΜΑΤΩΝ ΤΥΡΟΥ" ΕΧΟΥΝ ΑΣΒΕΣΤΑΛΚΑΛΙΚΑ ΧΑΡΑΚΤΗΡΙΣΤΙΚΑ ΚΑΙ ΕΙΝΑΙ ΟΡΟΓΕΝΕΤΙΚΟΙ ΑΝΔΕΣΙΤΕΣ ΕΩΣ ΒΑΣΑΛΤΑΝΔΕΣΙΤΕΣ, ΑΠΟΤΕΛΕΣΜΑ ΜΙΑΣ ΑΣΒΕΣΤΑΛΚΑΛΙΚΗΣ ΗΦΑΙΣΤΕΙΟΤΗΤΑΣ ΣΤΟ ΧΩΡΟ ΜΙΑΣ ΖΩΝΗΣ ΚΑΤΑΒΥΘΙΣΗΣ. ΠΥΡΟΚΛΑΣΤΙΚΑ ΑΝΑΠΤΥΣΣΟΝΤΑΙ ΣΕ ΜΕΓΑΛΗ ΕΚΤΑΣΗ, ΕΝΩ ΟΙ ΛΑΒΕΣ, ΣΥΧΝΑ ΠΟΡΦΥΡΙΤΙΚΕΣ, ΕΧΟΥΝ ΜΙΚΡΟΤΕΡΗ ΑΝΑΠΤΥΞΗ. 3. ΚΑΤΑ ΤΟ ΣΤΑΔΙΟ ΤΗΣ ΗΦΑΙΣΤΕΙΟΤΗΤΑΣ ΣΥΝΕΒΗ ΥΔΡΟΘΕΡΜΙΚΗ ΕΞΑΛΛΟΙΩΣΗ ΤΩΝ ΗΦΑΙΣΤΙΤΩΝ, ΑΝΑΛΟΓΗ ΜΕ ΤΗΝ ΕΞΑΛΛΟΙΩΣΗ ΠΟΥ ΠΑΡΑΤΗΡΕΙΤΑΙ ΣΕ ΣΥΓΧΡΟΝΑ ΓΕΩΘΕΡΜΙΚΑ ΠΕΔΙΑ ΣΕ ΘΕΣΕΙΣ ΥΠΟΘΑΛΑΣΣΙΑΣ ΗΦΑΙΣΤΕΙΟΤΗΤΑΣ, ΣΑΝ ΑΠΟΤΕΛΕΣΜΑ ΑΛΛΗΛΕΠΙΔΡΑΣΗΣ ΘΑΛΑΣΣΙΝΟΥ ΝΕΡΟΥ ΜΕ ΤΟ ΗΦΑΙΣΤΕΙΑΚΟ ΠΕΤΡΩΜΑ. 4. Η ΜΕΤΑΛΛΟΦΟΡΙΑ ΔΙΑΣΠΑΡΤΩΝ ΘΕΙΟΥΧΩΝ CU(-FE) ΚΑΙ STOCKWORK ΘΕΙΟΥΧΩΝ PB-ZN- FE-CU, ΑΝΑΠΤΥΣΣΕΤΑΙ ΜΕΣΑ ΣΕ ΗΦΑΙΣΤΕΙΑΚΑ ΠΕΤΡΩΜΑΤΑ, ΕΝΩ Η ΣΤΡΩΜΑΤΟΕΙΔΗΣ ΜΕΤΑΛΛΟΦΟΡΙΑ ΓΑΛΗΝΙΤΗ-ΒΑΡΙΤΗ ΑΝΩ ΤΥΡΟΥ ΦΙΛΟΞΕΝΕΙΤΑΙ ΣΕ ΑΝΘΡΑΚΙΚΟ ΠΕΤΡΩΜΑ. ΤΟ ΜΕΤΑΛΛΕΥΜΑ ΘΕΙΟΥΧΩΝ PB-ZN-FE-CU - ΑΠΟ ΤΑ ΥΠΑΡΧΟΝΤΑ ΔΕΔΟΜΕΝΑ - ΦΑΙΝΕΤΑΙ ΟΤΙ ΕΙΝΑΙ ΕΠΙΓΕΝΕΤΙΚΟ ΚΑΙ ΣΥΝΔΕΕΤΑΙ ΓΕΝΕΤΙΚΑ ΜΕ ΕΞΑΛΛΟΙΩΣΗ "ΧΑΛΑΖΙΑΚΟΥ-ΧΛΩΡΙΤΙΚΟΥ-ΣΕΡΙΚΙΤΙΚΟΥ" ΤΥΠΟΥ ΗΦΑΙΣΤΕΙΑΚΩΝ ΤΟΦΦΩΝ. Η ΥΠΑΡΞΗ ΔΥΟ ΔΙΑΦΟΡΕΤΙΚΩΝ ΤΥΠΩΝ ΜΕΤΑΛΛΟΦΟΡΙΑΣ, ΑΦΕΝΟΣ ΔΙΑΣΠΑΡΤΩΝ ΘΕΙΟΥΧΩΝ CU(-FE) ΚΑΙ ΑΦΕΤΕΡΟΥ STOCKWORK PB-ZN-FE-CU, ΑΠΟΔΙΔΕΤΑΙ ΣΤΗ ΔΙΑΦΟΡΕΤΙΚΗ ΔΙΑΛΥΤΟΤΗΤΑ CU-FE ΚΑΙ PB-ZN ΣΕ ΘΕΡΜΑ ΧΛΩΡΙΟΥΧΑ ΔΙΑΛΥΜΑΤΑ ΚΑΙ ΣΤΗ ΜΙΚΡΗ ΑΝΑΛΟΓΙΑ ΝΕΡΟΥ/ΠΕΤΡΩΜΑΤΟΣ, ΠΟΥ ΥΠΑΡΧΕΙ ΣΕ ΒΑΘΥΤΕΡΟΥΣ ΟΡΙΖΟΝΤΕΣ ΤΟΥ ΗΦΑΙΣΤΕΙΑΚΟΥ ΣΧΗΜΑΤΙΣΜΟΥ. (ΠΕΡΙΚΟΠΗ

Late Permian-Early Triassic igneous activity in the Attic Cycladic Belt (Attica): New geochronological data and geodynamic implications

Igneous rocks of the Attic Cycladic Belt (ACB) formed prior to the Alpine orogeny have received relatively little attention, especially regarding their crystallisation age. New U-Pb SHRIMP zircon data from mylonitised metagranitoid rocks within metapelit

Origin and timing of barite, base-metal and gold deposits on Mykonos island in the Aegean back-arc domain (Greece)

International audienc

Origin and timing of barite, base-metal and gold deposits on Mykonos island in the Aegean back-arc domain (Greece)

International audienc

Characterization of the siliceous rocks at Stelida, an early prehistoric lithic quarry (Northwest Naxos, Greece), by petrography and geochemistry: A first step towards chert sourcing

International audienceThis article presents the results of a combined petrographic and geochemical characterization study of raw materials from the early prehistoric chert source of Stelida, on Naxos (Cyclades, Greece). The project represents the first step in a larger provenience studies programme dedicated to documenting which communities exploited this source during the Lower Palaeolithic to Mesolithic (>= 250,000-9000 BP). Field-and lab-based studies conclude that the cherts originated by pervasive silicification of the upper part of a clastic sedimentary sequence by hydrothermal fluids moving along a detachment fault separating them from the underlying Naxos granodioritic intrusive. Quartz is the dominant mineral, while zircon, anatase, hematite and barite are accessories. Petrographic features that are considered characteristic of the Stelida raw materials (e.g. colour and lustre, massive microcrystalline texture, abundant cavities, quartz crystals projecting into cavities and thin quartz veinlets crosscutting bedding planes) are described. The cherts are strongly depleted in trace and Rare Earth elements. The petrographic and geochemical study of any stone tool made of chert showing similar macro-and microtextures, mineralogical features, and geochemical signature indicates a potential Stelida origin

Early Holocene Interaction in the Aegean Islands: Mesolithic Chert Exploitation at Stélida (Naxos, Greece) in Context

International audienceThis paper details the Mesolithic component (potential date 9000-7000 cal. BC) of a recent geo-archaeological survey of Stélida, a chert source and associated stone tool making workshops on Naxos, the largest of the Cycladic islands (southern Greece). The history of research is provided, followed by a precis of the survey methods, and the results of the geological study. The techno-typological attributes of the Mesolithic chipped stone artefacts are detailed, and the material’s intraite distribution discussed, followed by an in-depth comparison with Early Holocene material from elsewhere in the southern Aegean, both insular and continental, concluding that the assemblage can be situated within an “island lithic tradition”. Stélida is then located within the wider context of the Aegean Mesolithic to consider issues of chronology and the site’s significance within broader debates concerning the nature of Early Holocene insular activity and colonization. While the Mesolithic activity at Stélida forms part of an increasing data-set of Early Holocene sites in the Cyclades, Crete, Dodecanese and Sporades, it remains unclear as to whether (a) this evidence attests to perennial island habitation, or (b) to what extent these sites form part of a “slow-fuse” colonisation process, or simply a period of intensified maritime activity and/or the remnants of failed long-term settlement

Early Holocene Interaction in the Aegean Islands: Mesolithic Chert Exploitation at Stélida

This paper details the Mesolithic component (potential date 9000-7000 cal. BC) of a recent geo-archaeological survey of Stélida, a chert source and associated stone tool making workshops on Naxos, the largest of the Cycladic islands (southern Greece). The history of research is provided, followed by a precis of the survey methods, and the results of the geological study. The techno-typological attributes of the Mesolithic chipped stone artefacts are detailed, and the material’s intra-site distribution discussed, followed by an in-depth comparison with Early Holocene material from elsewhere in the southern Aegean, both insular and continental, concluding that the assemblage can be situated within an “island lithic tradition”. Stélida is then located within the wider context of the Aegean Mesolithic to consider issues of chronology and the site’s significance within broader debates concerning the nature of Early Holocene insular activity and colonization. While the Mesolithic activity at Stélida forms part of an increasing data-set of Early Holocene sites in the Cyclades, Crete, Dodecanese and Sporades, it remains unclear as to whether (a) this evidence attests to perennial island habitation, or (b) to what extent these sites form part of a “slow-fuse” colonisation process, or simply a period of intensified maritime activity and/or the remnants of failed long-term settlement

Environmental characterisation of the Kirki (NE Greece) flotation tailings

Δημοσίευση σε επιστημονικό περιοδικόSummarization: This article presents the first thorough geochemical study of the tailings produced after processing and disposal of the Agios Filippos (Kirki, northeast Greece) high sulfidation epithermal deposit. The acid generation potential of the tailings was determined with the use of the acid/base accounting technique, and their toxicity was assessed with the toxicity characteristics leaching procedure (TCLP). The data derived from this study may be used: 1) in future geo-environmental modeling of high-sulfidation epithermal-type mineralization, 2) in forensic investigations aiming at identification of pollution sources, migration routes, mobility, fate and bio-available fractions of the most hazardous contaminants, and 3) during screening and selection of feasible remediation schemes in waste disposal sites.Παρουσιάστηκε στο: Environmental Forensic