Mapping and new structural observations on Kythera demonstrate the presence of a major detachment fault, which borders the domed structure of a metamorphic core complex. A three stage extensional context accompanied the exhumation of HP-rocks in Kythera. Early ductile structures near the mapped detachment fault indicate its initiation under NE-trending extension. Later ductile, ductile-brittle and some brittle structures, in the metamorphic unit near the detachment, indicate a significant NW-SE extension along-the-arc. The youngest brittle structures indicate return to NE-SW extension. Thermochronological and structural data show the intensive extension along-the-arc in the Kythera area fades out in both directions along the Cretan-Peloponnese ridge. The exhumation of HP-rocks in the Hellenic forearc ridge and arc-parallel extension in the Hellenic forearc ridge are tectonic episodes resulting from simultaneously high rates of trench rollback and slab retreat and consequent expansion of the arc of the overriding Aegean plate and simultaneously, the bending of the arc from a more rectilinear shape. Local arc-parallel extension occurred where stretching was a maximum, and occurred in a position of oblique late convergence along the arc.
Determination of radiation damage (RD) in zircon using Raman spectroscopy and annealing experiments shows wavenumber shifts to correlate strongly with uranium concentration of zircon (Uz). Consequently, Raman spectroscopy of v3[SiO4] can potentially determine the Uz. There is a progressively increasing range of wavenumber shift due to Uz increase, which reflects the ratio of intact versus distorted crystallinity. The time since crystallization or last annealing of the zircon will control the amount of radiation damage and the Raman wavenumber shift for zircons with a given Uz. A longer time is required for a low-uranium zircon to reach the same amount of alpha and fission damage events of a high-uranium zircon, in order for both to show equal wavenumber shift. Time distinguishes zircons of same Uz, which show differences in the Raman wavenumber. The correlation of the Raman wavenumber range and Uz may permit the development of a new chronometer using Raman measurements only for determining U concentration.
Marsellos, A.E., 2008. Extension and exhumation of the Hellenic
forearc; and radiation damage in zircons. Unpublished PhD
dissertation, State University of New York at Albany. 754 pp.,
+xix; 4 plates/folded maps.
University at Albany Science Library call number: SCIENCE MIC Film QE 40 Z899 2008 M37
Copies of this PhD dissertation can be ordered from Proquest UMI (this is available as a pdf file with all pages as greyscale images; 116MB file!)
Front matter (title, table of contents, abstract, acknowledgements) - 0.2MB pdf file
Figure pages in dissertation (colour and greyscale photos and figures, with captions): - 14.3MB pdf file
Plate A - Structural
map of the Phyllite-Quartzite Unit of central Peloponnese
(coloured map of structural and cooling age data on topographic base; scale 1:126,500) - 3.2MB pdf file
Plate B - Structural map of the Phyllite-Quartzite Unit of southern Peloponnese
(coloured map of structural and cooling age data on topographic base; scale 1:46,000) - 1.3MB pdf file
Plate C - Geological map of northern Kythera Island with structural and cooling age data
(coloured geological map with structural and cooling age data on topographic base; scale 1:15,000) - 4.3MB pdf file
Plate D - Structural map of the Phyllite-Quartzite Unit of western Crete
(coloured map of structural and cooling age data on topographic base; scale 1:68,000) - 1.9MB pdf file