Localized intensive ductile and ductile-brittle extension of along-thearc orientation is prominent in Phyllite-Quartzite unit (PQU) rocks in Kythera and the adjacent southeastern Peloponnese but declines in prominence to the north and to the south along the Cretan-Peloponnese ridge. Using zircon and apatite fission track dating we find that this structural characteristic is correlated with the youngest zircon fission track cooling ages of 14 to 9 Ma, and with the highest pressure-temperature condition recorded in the metamorphic rocks below the structural detachment. The cooling ages of the high pressure Phyllite-Quartzite unit (PQU) rocks along the Hellenic forearc ridge show that exhumation migrated from both Crete and from the Peloponnese to the area with the youngest ages, in Kythera and the southeastern Peloponnese. Starting in the Early Miocene, and continuing to the present, trenchrollback and slab retreat expanded the Hellenic arc, and this bending of the arc from an initial more rectilinear geometry increased areas of oblique convergence and we suggest this localized the subsequent arc-parallel extension and local enhanced exhumation of HP-rocks. The Zircon FT exhumation ages from the arc-parallel stretching episode restrict the ductile part of this episode in exposed rocks to between about 14 and 9 Ma. Apatite FT ages suggest brittle along-arc extension continued to about 7 Ma. This episode is proposed to be the result of a temporary higher rate of rollback and slab retreat. Younger normal faults, including those which define the margins of the present Hellenic Arc, show return to arc-normal extension.

This research introduces a hybrid model for forecasting river flood events with an example of the Mohawk River in New York. Time series analysis and artificial neural networks are combined for the explanation and forecasting of the daily water discharge using hydrogeological and climatic variables. A low pass filter (Kolmogorov–Zurbenko filter) is applied for the decomposition of the time series into different components (long, seasonal, and short-term components). For the prediction of the water discharge time series, each component has been described by applying the multiple linear regression models (MLR), and the artificial neural network (ANN) model. The MLR retains the advantage of the physical interpretation of the water discharge time series. We prove that time series decomposition is essential before the application of any model. Also, decomposition shows that the Mohawk River is affected by multiple time scale components that contribute to the hydrologic cycle of the included watersheds. Comparison of the models proves that the application of the ANN on the decomposed time series improves the accuracy of forecasting flood events. The hybrid model which consists of time series decomposition and artificial neural network leads to a forecasting up to 96% of the explanation for the water discharge time series.

Detailed mapping and new structural observations on Kythera demonstrate that there is a major detachment fault, here termed the Potamos detachment fault (PDF), exposed on the northern part of the island and bordering the domed structure of a metamorphic core complex. The detachment forms the contact of contrasting metamorphic and nonmetamorphic units, and both ductile and brittle structures are found, related to its extensional development. The earliest Potamos mylonites, as well as some other early ductile structures near the mapped detachment fault, indicate initiation of the PDF under NE-trending extension, in mid-to late Miocene time. Later ductile, ductile-brittle, and some brittle structures in the metamorphic unit near the detachment indicate (in contrast) a significant NW-SE extension along the forearc ridge. The younger brittle structures indicate return to NE-SW extension. Late Miocene-Pliocene strata cover the detachment unconformably and are affected only by the late faults. Trench rollback and slab retreat of the subducting African lithosphere in the late Miocene requires expansion and increased curvature of the Hellenic (Crete-Peloponnese) forearc ridge. Differential movement between and vertical axis rotation of segments of the forearc ridge may have localized along-arc stretching. Cross-ridge strike-slip faults may be linked to the later parts of this process. Evidence of young E-W dextral faulting is seen in northern Kythera outcrops, related to a significant submarine fault of this type located between Kythera and the Peloponnese.

Radiation damage of natural and synthetic zircon grains is evaluated by Raman spectroscopy to understand annealing and stability of fission tracks. Analyses focus on a suite of 338 Paleozoic detrital zircon grains from metamorphosed strata in the Hellenic forearc that were variably annealed by a Miocene thermal event, as well as a suite of 97 synthetic zircon grains. The Raman wavenumber shift of ν 3 [SiO 4 ] reveals that radiation damage and damage distribution in this suite mainly depends on uranium concentration. In zircon with similar uranium concentration, the Raman wavenumber shift allows for the determination of radiation damage in different crystals, which is a function of effective accumulation time. Nine detrital zircons grains with moderate radiation damage were stepwise annealed at 1000 and 1400 °C, which resulted in progressive removal of radiation damage revealed in an increase of ν 3 [SiO 4 ] peak positions. For a partly reset sample that was brought to temperatures of ~350 °C in a geologic setting (Hellenic forearc), we use the Raman measurements and uranium determination to estimate a Zircon Damage Discrimination Factor (Z RDD ), which is our attempt to estimate only radiation damage in single grains by accounting for affects of the uranium atom in the Raman wavenumber. This discrimination allows for a separation of zircon fission track (ZFT) ages of single ages based on grains that have a low track retention (high damage, fully reset grain), thus refining the age determination of cooling in a rock that shows variable resetting.