Late quaternary rates of stream incision in northeast Peloponnese, Greece

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THE GEOMORPHOLOGICAL EVOLUTION IN AND AROUND THE ARGINE PLAIN SINCE THE QUATERNARY

THE PURPOSE OF THIS STUDY IS TO INTERPRET GEOMORPHOLOGICALLY THE PALEOGEOGRAPHICAL EVOLUTION OF THE BROADER AREA OF THE ARGIVE PLAIN DURING THE QUATERNARY. FOR THIS REASON GEOMORPHOLOGICAL MAPPING AND LITHOSTRATIGRAPHIC STUDY OF PHYSICALSECTIONS, ARCHEOLOGICAL EXCAVATION AND BONE HOLES WERE PERFORMED. THE GEOMORPHOLOGICAL EVOLUTION OF THE BROADER AREA OF THE ARGIVE PLAIN IS DISTINGUISHED INTO TWO MAIN CYCLES. THE FIRST AND OLDER ONE INFLUENCED THE ALPINE BEDROCK GIVINGTWO SHAPED VALLEYS AND KARSTIC FEATURES. THE LATTER IS RELATED TO POST-PLEIOCENE EVOLUTION. AFTER THE DEPOSITION OF THE PLIO-PLEISTOCENE, THE NORTHERN AREA OF THE ARGIVE PLAIN UPLIFTED DUE TO THE CONTINUED FAULT ACTIVITY WHILE THE CENTRAL PART SUBSIDED. DURING THE MIDDLE QUATERNARY A REJUVENATION OF THE PREVIOUS DRAINAGE SYSTEM OCCURED, TOGETHER WITH THE MAIN PHASE OF THE EVOLUTION OF GORGESAND THE FORMATION OF VALLEYS INTO THE PLIO- PLEISTOCENE SEDIMENTS . THE MAIN DEPOSITIONAL PHASE OF FANS HAVING TWO SOIL LEVELS IS ATTRIBUTED TO THE WURM PERIOD. THE OBSERVED EROSIONAL PHASE OF THESE FANS STARTED BEFORE THE MYCENEAN ERA AND CONTINUED AFTER IT CAUSING THE FORMATION OF A 20 M TERRACE. THE MOST RECENTDEPOSITIONAL PHASE OF THE MATERIAL OF THE INNER TERRACE, 2 M HIGH IS ASCRIBED TO THE POST ROMAN TIMES AND IT IS FOLLOWED BY THE MODERN PHASE OF EROSION. 14C DATING AND ARCHAEOLOGICAL EVIDENCE GAVE AN ESTIMATE OF THE RATE OF THE TERRESTRIAL SEDIMENTATION IN THE PLAIN.ΣΚΟΠΟΣ ΑΥΤΗΣ ΤΗΣ ΜΕΛΕΤΗΣ ΕΙΝΑΙ ΝΑ ΕΡΜΗΝΕΥΘΕΙ ΓΕΩΜΟΡΦΟΛΟΓΙΚΑ Η ΠΑΛΑΙΟΓΕΩΓΡΑΦΙΚΗ ΕΞΕΛΙΞΗ ΤΗΣ ΕΥΡΥΤΕΡΗΣ ΠΕΡΙΟΧΗΣ ΤΟΥ ΑΡΓΟΛΙΚΟΥ ΠΕΔΙΟΥ ΚΑΤΑ ΤΟ ΤΕΤΑΡΤΟΓΕΝΕΣ. ΠΡΟΣ ΤΟΥΤΟ ΕΓΙΝΕ ΓΕΩΜΟΡΦΟΛΟΓΙΚΗ ΧΑΡΤΟΓΡΑΦΗΣΗ ΤΗΣ ΠΕΡΙΟΧΗΣ ΚΑΙ ΛΙΘΟΣΤΡΩΜΑΤΟΓΡΑΦΙΚΗ ΜΕΛΕΤΗ ΦΥΣΙΚΩΝ ΤΟΜΩΝ, ΑΡΧΑΙΟΛΟΓΙΚΩΝ ΑΝΑΣΚΑΦΩΝ ΚΑΙ ΤΟΜΩΝ ΓΕΩΤΡΗΣΕΩΝ. Η ΓΕΩΜΟΡΦΟΛΟΓΙΚΗ ΕΞΕΛΙΞΗ ΤΗΣ ΠΕΡΙΟΧΗΣ ΔΙΑΚΡΙΝΕΤΑΙ ΣΕ ΔΥΟ ΧΡΟΝΙΚΕΣ ΠΕΡΙΟΔΟΥΣ. Η ΠΡΩΤΗ ΚΑΙ ΠΑΛΑΙΟΤΕΡΗ ΕΔΩΣΕ ΓΕΩΜΟΡΦΕΣ ΣΤΟ ΑΛΠΙΚΟ ΥΠΟΒΑΘΡΟ (ΕΠΙΦΑΝΕΙΕΣ ΙΣΟΠΕΔΩΣΗΣ ΚΑΡΣΤΙΚΕΣ ΜΟΡΦΕΣ, ΑΝΕΝΕΡΓΕΣ ΚΟΙΛΑΔΕΣ, Η ΔΕΥΤΕΡΗ ΚΑΙ ΝΕΩΤΕΡΗ ΣΥΣΧΕΤΙΖΕΤΑΙ ΜΕ ΤΗΝ ΜΕΤΑ- ΠΛΕΙΟΚΑΙΝΙΚΗ ΕΞΕΛΙΞΗ. ΜΕΤΑ ΤΗΝ ΑΠΟΘΕΣΗ ΤΩΝ ΠΛΕΙΟ-ΠΛΕΙΣΤΟΚΑΙΝΙΚΩΝ ΙΖΗΜΑΤΩΝ ΚΑΙ ΕΞ'ΑΙΤΙΑΣ ΤΗΣ ΣΥΝΕΧΙΖΟΜΕΝΗΣ ΤΕΚΤΟΝΙΚΗΣ ΔΡΑΣΤΗΡΙΟΤΗΤΑΣ ΤΟ ΒΟΡΕΙΟ ΤΜΗΜΑ ΤΗΣ ΠΕΡΙΟΧΗΣ ΑΝΥΨΩΘΗΚΕ ΕΝΩ ΤΟ ΚΕΝΤΡΙΚΟ ΒΥΘΙΣΤΗΚΕ. ΣΤΗΝ ΠΕΡΙΟΔΟ ΤΟΥ ΜΕΣΟΥ-ΤΕΤΑΡΤΟΓΕΝΟΥΣ ΑΠΟΔΙΔΕΤΑΙ Η ΑΝΑΓΕΝΝΗΣΗ ΤΩΝ ΚΛΑΔΩΝ ΤΟΥ ΠΑΛΑΙΟΥ ΥΔΡΟΓΡΑΦΙΚΟΥ ΔΙΚΤΥΟΥ, Η ΚΥΡΙΑ ΦΑΣΗ ΕΞΕΛΙΞΗΣ ΤΩΝ ΦΑΡΑΓΓΙΩΝ ΚΑΙ Η ΔΗΜΙΟΥΡΓΙΑ ΚΟΙΛΑΔΩΝ ΣΤΙΣ ΠΛΕΙΟΠΛΕΙΣΤΟΚΑΙΝΙΚΕΣ ΑΠΟΘΕΣΕΙΣ. Η ΚΥΡΙΑ ΦΑΣΗ ΑΠΟΘΕΣΗΣ ΤΩΝ ΡΙΠΙΔΙΩΝ ΜΕ ΔΥΟ ΕΔΑΦΙΚΟΥΣ ΟΡΙΖΟΝΤΕΣ ΑΠΟΔΙΔΕΤΑΙ ΣΤΗΝ ΠΕΡΙΟΔΟ ΤΟΥ WURM ΕΝΩ Η ΦΑΣΗ ΔΙΑΒΡΩΣΗΣ ΤΩΝ ΡΙΠΙΔΙΩΝ ΑΡΧΙΣΕ ΠΡΙΝ ΑΠΟ ΤΗΝ ΑΝΑΒΑΘΜΙΔΑ ΤΩΝ 20 Μ. Η ΝΕΑ ΦΑΣΗ ΑΠΟΘΕΣΗΣ ΤΟΥ ΥΛΙΚΟΥ ΤΗΣ ΕΣΩΤΕΡΙΚΗΣ ΑΝΑΒΑΘΜΙΔΑΣ ΤΩΝ 2 Μ ΑΠΟΔΙΔΕΤΑΙ ΣΤΟΥΣ ΜΕΤΑΡΩΜΑΙΚΟΥΣ ΧΡΟΝΟΥΣ ΕΝΩ Η ΦΑΣΗ ΔΙΑΒΡΩΣΗΣ ΑΥΤΗΣ ΕΙΝΑΙ ΣΥΓΧΡΟΝΗ. ΑΠΟ ΧΡΟΝΟΛΟΓΗΣΕΙΣ ΜΕ C14 ΚΑΙ ΑΠΟ ΑΡΧΑΙΟΛΟΓΙΚΕΣ ΚΑΤΑΣΚΕΥΕΣ ΥΠΟΛΟΓΙΣΘΗΚΕ Ο ΡΥΘΜΟΣ ΧΕΡΣΑΙΑΣ ΙΖΗΜΑΤΟΓΕΝΕΣΗΣ ΣΤΟ ΑΡΓΟΛΙΚΟ ΠΕΔΙΟ

The morphotectonic evolution of southern half of Kythira Island (Ionian sea, Greece) during the Quaternary

Kythira island is located between Peloponnese and Crete along the Hellenic island arc. The morpho tectonic study of this island could provide useful clues about the evolution of this area. The study focused on the southern part of the island where most of the characteristic landforms of uplift are found (terraces, gorges and notches). Large scale geomorphological mapping was performed in order to determine the most significant landforms of the area such as planation surfaces, marine terraces, gorges, knick points, cliffs and notches. It is concluded that the general morphology and evolution of the southern part of the island is depended primarily on the tectonic regime of the area which is exemplified by characteristic landforms in a series of well distinguished eight uplifted marine terraces on the eastern and six in the western part, marine notches and inclined planation surfaces, gorges and knick points indicating a continuous uplift of the island during the Quaternary. Finally, an average uplift rate of about 0.13 mm/yr for the Quaternary period is determined for the study area

Μorphometric Analysis for the Assessment of Relative Tectonic Activity in Evia Island, Greece

The aim of this study is to evaluate the relative tectonic activity in the north part of the Evia Island, located in Central Greece, and to investigate the contribution of neotectonic processes in the development of the fluvial landscape. Five morphometric parameters, including Drainage Basin Slope (Sb), Hypsometric Integral (Hi), Asymmetry Factor (Af), Relief Ratio (Rh), and Melton’s Ruggedness Number (M), were estimated for a total of 189 drainage basins. The catchments were classified into two groups, according to the estimated values of each morphometric parameter, and maps showing their spatial distribution were produced. The combination of the calculated morphometric parameters led to a new single integrated Index of relative tectonic activity (named Irta). Following this indexing, the basins were characterized as of low, moderate, or high relative tectonic activity. The quantitative analysis showed that the development of the present drainage systems and the geometry of the basins of the study area have been influenced by the tectonic uplift caused by the activity of two NW-SE trending offshore active normal fault systems: the north Gulf of Evia fault zone (Kandili-Telethrion) and the Aegean Sea fault zone (Dirfis), respectively. The spatial distribution of the values of the new integrated index Irta showed significant differences among the drainage basins that reflect differences in relative tectonic activity related to their location with regard to the normal fault systems of the study area

Assessment of Neotectonic Landscape Deformation in Evia Island, Greece, Using GIS-Based Multi-Criteria Analysis

This study deals with the assessment and mapping of neotectonic landscape deformation in the northern part of the Evia Island (Central Greece). Multi-Criteria Decision Analysis (MCDA) utilizing Analytic Hierarchy Process (AHP) and Weighted Linear Combination (WLC) procedures were conducted for the calculation of the Neotectonic Landscape Deformation Index (NLDI). The study is based on the combination of morphotectonic, geomorphological and geological parameters. The GIS-based spatial MCDA led to the classification of the study area into five classes of neotectonic deformation (from very low to very high) and to a neotectonic deformation map. The results were compared with the outputs of a relative tectonic activity classification approach based on quantitative geomorphic analysis at a regional scale, including site-specific field observations. Areas of high and very high deformation are related to the major active faults of Dirfis, Kandili and Gregolimano–Telethrio. Other minor active normal faults of medium to high seismic risk level, affecting the northern and northeastern parts of the island, are also associated with areas of intense landscape neotectonic deformation

Soil Loss Potential Assessment for Natural and Post-Fire Conditions in Evia Island, Greece

A devastating forest fire in August 2021 burned about 517 km2 of the northern part of Evia Island, affecting vegetation, soil properties, sediment delivery and the hydrological response of the catchments. This study focuses on the estimation of the annual soil loss in the study area under natural (pre-fire) and post-fire conditions. The assessment of the soil loss potential was conducted with the application of the Universal Soil Loss Equation (USLE), which is an empirical equation and an efficient way to predict soil loss. The USLE factors include rainfall erosivity (R), soil erodibility (K), the slope and slope length factor (LS), the cover management factor (C) and the erosion control practice factor (P). The USLE quantified the annual soil erosion (in t/ha/year) for both pre- and post-wildfire conditions, and the study area has been classified into various soil loss categories and soil erosion intensity types. The results showed that the annual soil loss before the forest fires ranged from 0 to 1747 t/ha, with a mean value of 253 t/ha, while after the fire the soil loss significantly increased (the highest annual soil loss was estimated at 3255 t/ha and the mean value was 543 t/ha). These values demonstrate a significant post-fire change in mean annual soil loss that corresponds to an increase of 114% compared to the pre-fire natural condition. The area that is undergoing high erosion rates after the extreme wildfire event increased by approximately 7%, while the area of moderate rates increased by 2%. The calculated maximum potential of soil erosion, before and after the 2021 extreme wildfire event, has been visualized on spatial distribution maps of the average annual soil loss for the study area. The present study underlines the significant post-fire increase in soil loss as part of the identification of the more vulnerable to erosion areas that demand higher priority regarding the protective/control measures

Soil Loss Potential Assessment for Natural and Post-Fire Conditions in Evia Island, Greece

A devastating forest fire in August 2021 burned about 517 km2 of the northern part of Evia Island, affecting vegetation, soil properties, sediment delivery and the hydrological response of the catchments. This study focuses on the estimation of the annual soil loss in the study area under natural (pre-fire) and post-fire conditions. The assessment of the soil loss potential was conducted with the application of the Universal Soil Loss Equation (USLE), which is an empirical equation and an efficient way to predict soil loss. The USLE factors include rainfall erosivity (R), soil erodibility (K), the slope and slope length factor (LS), the cover management factor (C) and the erosion control practice factor (P). The USLE quantified the annual soil erosion (in t/ha/year) for both pre- and post-wildfire conditions, and the study area has been classified into various soil loss categories and soil erosion intensity types. The results showed that the annual soil loss before the forest fires ranged from 0 to 1747 t/ha, with a mean value of 253 t/ha, while after the fire the soil loss significantly increased (the highest annual soil loss was estimated at 3255 t/ha and the mean value was 543 t/ha). These values demonstrate a significant post-fire change in mean annual soil loss that corresponds to an increase of 114% compared to the pre-fire natural condition. The area that is undergoing high erosion rates after the extreme wildfire event increased by approximately 7%, while the area of moderate rates increased by 2%. The calculated maximum potential of soil erosion, before and after the 2021 extreme wildfire event, has been visualized on spatial distribution maps of the average annual soil loss for the study area. The present study underlines the significant post-fire increase in soil loss as part of the identification of the more vulnerable to erosion areas that demand higher priority regarding the protective/control measures

Late Quaternary Marine Terraces and Tectonic Uplift Rates of the Broader Neapolis Area (SE Peloponnese, Greece)

Marine terraces are geomorphic markers largely used to estimate past sea-level positions and surface deformation rates in studies focused on climate and tectonic processes worldwide. This paper aims to investigate the role of tectonic processes in the late Quaternary evolution of the coastal landscape of the broader Neapolis area by assessing long-term vertical deformation rates. To document and estimate coastal uplift, marine terraces are used in conjunction with Optically Stimulated Luminescence (OSL) dating and correlation to late Quaternary eustatic sea-level variations. The study area is located in SE Peloponnese in a tectonically active region. Geodynamic processes in the area are related to the active subduction of the African lithosphere beneath the Eurasian plate. A series of 10 well preserved uplifted marine terraces with inner edges ranging in elevation from 8 ± 2 m to 192 ± 2 m above m.s.l. have been documented, indicating a significant coastal uplift of the study area. Marine terraces have been identified and mapped using topographic maps (at a scale of 1:5000), aerial photographs, and a 2 m resolution Digital Elevation Model (DEM), supported by extensive field observations. OSL dating of selected samples from two of the terraces allowed us to correlate them with late Pleistocene Marine Isotope Stage (MIS) sea-level highstands and to estimate the long-term uplift rate. Based on the findings of the above approach, a long-term uplift rate of 0.36 ± 0.11 mm a−1 over the last 401 ± 10 ka has been suggested for the study area. The spatially uniform uplift of the broader Neapolis area is driven by the active subduction of the African lithosphere beneath the Eurasian plate since the study area is situated very close (~90 km) to the active margin of the Hellenic subduction zone

Late Quaternary Marine Terraces and Tectonic Uplift Rates of the Broader Neapolis Area (SE Peloponnese, Greece)

Marine terraces are geomorphic markers largely used to estimate past sea-level positions and surface deformation rates in studies focused on climate and tectonic processes worldwide. This paper aims to investigate the role of tectonic processes in the late Quaternary evolution of the coastal landscape of the broader Neapolis area by assessing long-term vertical deformation rates. To document and estimate coastal uplift, marine terraces are used in conjunction with Optically Stimulated Luminescence (OSL) dating and correlation to late Quaternary eustatic sea-level variations. The study area is located in SE Peloponnese in a tectonically active region. Geodynamic processes in the area are related to the active subduction of the African lithosphere beneath the Eurasian plate. A series of 10 well preserved uplifted marine terraces with inner edges ranging in elevation from 8 ± 2 m to 192 ± 2 m above m.s.l. have been documented, indicating a significant coastal uplift of the study area. Marine terraces have been identified and mapped using topographic maps (at a scale of 1:5000), aerial photographs, and a 2 m resolution Digital Elevation Model (DEM), supported by extensive field observations. OSL dating of selected samples from two of the terraces allowed us to correlate them with late Pleistocene Marine Isotope Stage (MIS) sea-level highstands and to estimate the long-term uplift rate. Based on the findings of the above approach, a long-term uplift rate of 0.36 ± 0.11 mm a−1 over the last 401 ± 10 ka has been suggested for the study area. The spatially uniform uplift of the broader Neapolis area is driven by the active subduction of the African lithosphere beneath the Eurasian plate since the study area is situated very close (~90 km) to the active margin of the Hellenic subduction zone