ABSTRACT
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 Unpublished PhD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