Ο θεματικός πυρήνας του κεφαλαίου είναι η δομή της πλαστικής ζώνης διάτμησης του Φελλού στη Βορειοδυτική Άνδρο, η οποία μελετάται μέσα από την ανάλυση τομών. Η μελέτη αυτή είχε ως βασικούς στόχους (α) την κατανόηση της δομής και των κινηματικών χαρακτηριστικών της ζώνης διάτμησης, και (β) την καταγραφή των σταδίων κατασκευής του μυλωνιτικού ιστού. Κύριος σκοπός της μικροτεκτονικής ανάλυσης των μυλωνιτικών δειγμάτων είναι η παρουσίαση του προσανατολισμού του κινηματικού δείκτη σε σχέση με την φορά βύθισης γράμμωσης. / The core theme of the chapter is the structure of the plastic shear zone of Felloy in North Andros, which is studied through the analysis of sections.This study had as main objectives (a) the understanding of the structure and the kinematic characteristics of the shear zone, and (b) the recording of the construction stages of the tissue. The main purpose of the Microtectonics analyzing of the samples is the presentation of the orientation of the kinematic index in hense with the sink lineage.

Η γεωλογική εργασία αυτή έχει σκοπό τη χαρτογράφηση του Βορείου τμήματος, της νήσου Άνδρου μέσα από την αναγνώριση δομών. Ακόμη μέσα από την αναγνώριση των φάσεων παραμόρφωσης, αναλύονται τα εξελικτικά στάδια αυτής. Τέλος χρησιμοποιήθηκε το stereo 32 για την απεικόνιση δικτύων, όπου μέσα από αυτά οδηγηθήκαμε σε συμπεράσματα όσον αφορά τις διευθύνσεις στρωμάτων. / This geological paper has aim the mapping of Northern department,of the island Andros through the recognition of structures. Besides through the recognition of phases of deformity, are analyzed the evolutionary stages of the derfomity. Finally it was used stereo 32 for the depiction of networks, where through them we were led to conclusions with regard to the addresses of layers.

Η παρούσα πτυχιακή εργασία πραγματεύεται την κινηματική ανάλυση του καλύμματος των κυανοσχιστολίθων στην ευρύτερη περιοχή του Φελλού της νήσου Άνδρου. Ο σκοπός αυτής της εργασίας είναι να χαρτογραφηθεί η Βόρεια Άνδρος και να επέλθει μια βελτίωση στην ήδη υπάρχουσα χαρτογράφηση. Σύμφωνα λοιπόν με τα δεδομένα που συλλέχθηκαν, παρατηρήθηκαν οι εξής λιθολογίες: μαρμαρυγιακοί-χαλαζιακοί-χαλαζιαστριακοί σχιστόλιθοι, επιδοτιτικοί σχιστόλιθοι και τμήματα οφιολίθων. Τοπικά στους μαρμαρυγιακούς σχιστόλιθους παρεμβάλλονταν και τεφρά ασβεστιτικά μάρμαρα που όμως το ποσοστό τους είναι μικρό και δεν τα καθιστά χαρτογραφίσιμα. / This project deals with the kinematic analysis of the Blueschist unit of Andros island.

No description available.

A single-beam acoustic seabed classification system was used to map coral reef environments in the upper Florida Keys, USA, and the Bahamas. The system consisted of two components, both produced by the Quester Tangent Corporation. A QTCView Series V, operating with a 50 kHz sounder, was used for data acquisition, and IMPACT software was used for data processing and classification. First, methodological aspects of system performance were evaluated. Second, the system was applied to the assessment of grouper and snapper habitat. Two methodological properties were explored: transferability (i.e. mapping the same classes at multiple sites) and reproducibility (i.e. surveying one site multiple times). The transferability results showed that a two-class scheme of hard bottom and sediment could be mapped at four sites with overall accuracy ranging from 73% to 86%. The locations of most misclassified echoes had one of two characteristics: a thin sediment veneer overlying hard bottom or within-footprint relief on the order of 0.5 m or greater. Reproducibility experiments showed that consistency of acoustic classes between repeat transects over the same area on different days varied, for the most part, between 50% and 65%. Consistency increased to between 78% and 92% when clustering was limited to two acoustic classes, to between approximately 70% and 100% when only echoes acquired within two degrees of nadir in the pitch direction were used, and to between 81% and 87% when a limited set of features was used for classification. The assessment of grouper and snapper habitat addressed the question whether areas of high fish abundance were associated with characteristic acoustic or geomorphological signatures. The results showed, first, that the hard bottom / sediment classification scheme was a useful first step for stratifying survey areas to increase efficiency of grouper census efforts. Second, an index of acoustic variability complemented the hard bottom / sediment classification by further targeting areas of potential grouper habitat. Finally, five grouper and snapper spawning aggregation sites were all found to have similar associations with drowned shelf edge reefs in the upper Florida Keys.

The Aegean is a classic setting for studying exhumation of high-pressure (HP) metamorphic rocks. Two end-member models are proposed to explain the uplift of these rocks: core-complex style extension along low-angle normal faults and extrusion-wedge uplift. Extrusion-wedge underplating is the mechanism that exhumed HP rocks on Evia whereas Tinos hosts several detachments varying in age from 30-9 Ma. Andros, situated between them, may be the geological manifestation of the interplay of these processes and provides an opportunity to test these models. Detachments on NW Tinos and on Andros and the enigmatic low-angle Makrotantalon Unit contact on Andros were insufficiently dated prior to this study. Geo- and thermochronometrycombined with structural observations from sampling transects in the transport direction from (1) lower plate Cycladic Blueschist Unit on Andros and Tinos, (2) middle plate Makrotantalon Unit on Andros, and (3) hanging wall Upper Unit address these issues. Maximum depositional ages from detrital zircon U-Pb geochronometry and structures reveal Paleocene-Eocene syn-HP metamorphism thrusting resulted in an inversed-age relationship between the Permian Makrotantalon Unit and the underlying Triassic-Eocene Cycladic Blueschist Unit on Andros. The Makrotantalon Unit has an internal inversed stratigraphy whereas the Cycladic Blueschist Unit on Andros and Tinos appear stratigraphically intact. Structures and zircon and apatite (U-Th)/He ages in transects from NW Tinos (~12-8 Ma) and central Andros Cycladic Blueschist Unit (~13-7 Ma) indicate rapid cooling due to exhumation associated with the Livada Detachment. Older cooling ages (~16-10 Ma) and structures in the Makrotantalon Unit indicate later brittle strain localization on the Makrotantalon Thrust contact is accommodated by rheologically weaker serpentinites and calc-schists, resulting in slivering of the footwall under the Livada Detachment on Andros. Estimated mean cooling slip rates of the Livada Detachment on Andros of ~3.8 (+1.2/-1.3) km/Myr and 2.1 (+0.2/-0.2) km/Myr on NW Tinos resulted in minimum vertical exhumations of 15 km and 4 km, respectively. The NCDS here accommodated ~12-25% of 60 km of HP-rock exhumation from ~30-7 Ma. We present a tectonic model to elucidate the evolution of the Makrotantalon Unit and the magnitude, temporal, and spatial variability of exhumation via detachments on these islands. / text

The Aegean is a classic setting for studying exhumation of high-pressure (HP) metamorphic rocks. Two end-member models are proposed to explain the uplift of these rocks: core-complex style extension along low-angle normal faults and extrusion-wedge uplift. Extrusion-wedge underplating is the mechanism that exhumed HP rocks on Evia whereas Tinos hosts several detachments varying in age from 30-9 Ma. Andros, situated between them, may be the geological manifestation of the interplay of these processes and provides an opportunity to test these models. Detachments on NW Tinos and on Andros and the enigmatic low-angle Makrotantalon Unit contact on Andros were insufficiently dated prior to this study. Geo- and thermochronometrycombined with structural observations from sampling transects in the transport direction from (1) lower plate Cycladic Blueschist Unit on Andros and Tinos, (2) middle plate Makrotantalon Unit on Andros, and (3) hanging wall Upper Unit address these issues. Maximum depositional ages from detrital zircon U-Pb geochronometry and structures reveal Paleocene-Eocene syn-HP metamorphism thrusting resulted in an inversed-age relationship between the Permian Makrotantalon Unit and the underlying Triassic-Eocene Cycladic Blueschist Unit on Andros. The Makrotantalon Unit has an internal inversed stratigraphy whereas the Cycladic Blueschist Unit on Andros and Tinos appear stratigraphically intact. Structures and zircon and apatite (U-Th)/He ages in transects from NW Tinos (~12-8 Ma) and central Andros Cycladic Blueschist Unit (~13-7 Ma) indicate rapid cooling due to exhumation associated with the Livada Detachment. Older cooling ages (~16-10 Ma) and structures in the Makrotantalon Unit indicate later brittle strain localization on the Makrotantalon Thrust contact is accommodated by rheologically weaker serpentinites and calc-schists, resulting in slivering of the footwall under the Livada Detachment on Andros. Estimated mean cooling slip rates of the Livada Detachment on Andros of ~3.8 (+1.2/-1.3) km/Myr and 2.1 (+0.2/-0.2) km/Myr on NW Tinos resulted in minimum vertical exhumations of 15 km and 4 km, respectively. The NCDS here accommodated ~12-25% of 60 km of HP-rock exhumation from ~30-7 Ma. We present a tectonic model to elucidate the evolution of the Makrotantalon Unit and the magnitude, temporal, and spatial variability of exhumation via detachments on these islands.