Shoreline displacement drainage diversion in NW...
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Shoreline displacement drainage diversion in NW Peloponnese (Greece) Shoreline displacement, drainage diversion in NW Peloponnese (Greece) as result of the geology active tectonics and human activity as result of the geology, active tectonics and human activity d i th l t 100k during the last 100ky during the last 100ky FOUNTOULIS I MAVROULIS S VASSILAKIS E FOUNTOULIS I., MAVROULIS S., VASSILAKIS E. National and Kapodistrian University of Athens Faculty of Geology and Geoenvironment National and Kapodistrian University of Athens, Faculty of Geology and Geoenvironment D fD i T i dA li dG l Department of Dynamic Tectonic and Applied Geology Panepistimiopoli Zografou 15784 Athens email: fountoulis@geol uoa gr smavroulis@yahoo gr evasilak@geol uoa gr Panepistimiopoli, Zografou 15784 Athens, email: [email protected], [email protected], [email protected] ABSTRACT d Pineios River is the 3 rd longer river in Peloponnese and flows in Kyllini wider area which is located close to the Hellenic Arc system and is one of the most active areas in Greece with a great number of changes in the morphogenetic procedures taking place during the neotectonic period, as well as the last 100ky . Pineios River downstream crosses the study area and today flows out south of the Kyllini peninsula in the Ionian Sea The Greek historian geographer and philosopher Strabo reported in his Geography (1st century A D VIII 3 5 1) that the mouth of Pineios River was situated during the ancient times to the Pineios River downstream crosses the study area and today flows out south of the Kyllini peninsula, in the Ionian Sea. The Greek historian, geographer and philosopher Strabo reported in his Geography (1st century A.D. – VIII, 3,5,1) that the mouth of Pineios River was situated during the ancient times to the north of the Kyllini peninsula and the river flowed out into the Ionian Sea southwest of the Kotichi Lagoon. Furthermore, already published data indicate that the Pineios River may have shifted north and south of the Kyllini peninsula throughout the Holocene, it was diverted southwards in the late the 18 th century north of the Kyllini peninsula and the river flowed out into the Ionian Sea southwest of the Kotichi Lagoon. Furthermore, already published data indicate that the Pineios River may have shifted north and south of the Kyllini peninsula throughout the Holocene, it was diverted southwards in the late the 18 century A.D. and the current delta has been evolving since then. The effects of the geological, tectonic and neotectonic structure and the impact of the human presence and activity on the drainage network are presented here in order to determine the causes of the diversion of the Pineios River and the shoreline displacements. For this reason, we used, analyzed and evaluated (a) geomorphological, geological, tectonic and neotectonic data of the study area, (b) historical information and archaeological findings from buried and eroded archaeological sites of the wider study area, (c) published data related to drill cores and di b dt d (d) t llit d il ht f diff t id ll l ti ki ti diff ti l GPS t f th d fi iti f th t h li li It i ldd th t th t di d h li di l t d d i di i th lt f th bi ti f ti t t i radiocarbon dates and (d) satellite and aerial photos of different periods, as well as real-time kinematic differential GPS measurements for the definition of the current shorelineline. It is concluded that the studied shoreline displacements and drainage diversions are the result of the combination of active tectonics and human activity during the last 100 kyrs and human activity during the last 100 kyrs. 2 1 2 Pi i FZ i f th t tl ti t t i NW Pl (M li t l 2010 11 th IAEG C A kl d N Z l d) It i l td SSW f Sk li Mt t di E W 1 Pineios FZ is one of the most recently active structures in NW Peloponnese (Mavroulis et al. , 2010, 11 th IAEG Congress, Auckland, New Zealand). It is located SSW of Skolis Mt, trending E- W, dipping S wards and displaces a Tyrrhenian marine terrace forming well preserved fault scarps and consecutive triangular facets across active hill front The minimum fault slip rate based on the dipping S-wards and displaces a Tyrrhenian marine terrace forming well-preserved fault scarps and consecutive triangular facets across active hill front. The minimum fault slip rate based on the basal facet height was calculated as 0,15 mm/yr, while the maximum slip rate based on the maximum throw of the fault zone was calculated as 0,48 mm/yr (Mavroulis, et al. , 2010). The calculated basal facet height was calculated as 0,15 mm/yr, while the maximum slip rate based on the maximum throw of the fault zone was calculated as 0,48 mm/yr (Mavroulis, et al. , 2010). The calculated slip rates of Pineios FZ do not differ substantially from the slip rates in other neotectonic macrostructures of Peloponnese obtained by Koukouvelas et al. (1996, J. Geol. Soc. London, 153) and The Pineios River development and history takes place in one of the most tectonically Papanikolaou et al. (2007, Quatern. Int. 171-172). and seismically active areas in Greece. The intense tectonic activity in the area is due to its l ti th t l t f th H ll i d l t th t b d h One of the most characteristic effects of the Pineios FZ on the Pineios drainage network is the asymmetrical development of the western part of the Pineios drainage basin, where the Lower (alluvial) Pineios River shifts northwards and flows close and parallel to the northern drainage divide which is formed and determined by the Pineios FZ This asymmetry is clearly reflected in the location on the external part of the Hellenic arc and close to the convergent boundary where African plate is subducted beneath the European one as well as the diapirism of the evaporates (alluvial) Pineios River shifts northwards and flows close and parallel to the northern drainage divide, which is formed and determined by the Pineios FZ. This asymmetry is clearly reflected in the number size and order of the tributaries and subbasins on either side of the main river Especially north of the Lower Pineios River the 1 st and 2 nd order drainage basins prevail while higher order African plate is subducted beneath the European one as well as the diapirism of the evaporates. The recorded highest seismicity levels in Greece (Hatzfeld et al. , 1990, Geophys. J. Int. , 101) as number, size and order of the tributaries and subbasins on either side of the main river . Especially, north of the Lower Pineios River, the 1 and 2 order drainage basins prevail, while higher order drainage basins are absent. In contradiction, the 3 rd order drainage basins prevail covering an extended area south of the Lower Pineios River . The recorded highest seismicity levels in Greece (Hatzfeld et al. , 1990, Geophys. J. Int. , 101) as well as the generation of many strong earthquakes confirm the neotectonic studies, which show drainage basins are absent. In contradiction, the 3 order drainage basins prevail covering an extended area south of the Lower Pineios River . that the area is undergoing intense tectonic deformation. 4 5 The main neotectonic macrostructures of the wider study area are (a) the Erymanthos Mts horst (b) the Pyrgos Olympia basin and (c) the Kyllini horst These structures result from 4 5 Mts horst, (b) the Pyrgos - Olympia basin and (c) the Kyllini horst. These structures result from ongoing vertical movements and are faulted and/or bounded by fault zones ongoing vertical movements and are faulted and/or bounded by fault zones. The geological formations can be divided into alpine and post -alpine. The alpine formations belong to Pindos, Gavrovo - Tripolis and Ionian units. The post - alpine formations belong to the Pyrgos - Olympia basin, are of Pliocene and Quaternary age and lie f bl th li b t Th i hi l di t ib ti d th it f f i unconformably on the alpine basement. Their geographical distribution and the variety of facies (marine lagoonal lacustrine and terrestrial) clearly reflect vertical movements during the (marine, lagoonal, lacustrine and terrestrial) clearly reflect vertical movements during the neotectonic period and ongoing active tectonics neotectonic period and ongoing active tectonics. The most important fault zones in the study area are the Panopoulo fault zone (Panopoulo FZ), Pineios fault zone (Pineios FZ) and the strike - slip fault zone that gave rise to the Andravida earthquake (08-06-2008, ML=6,5). These major faults form several neotectonic bl k i th td i l di th G t i b (h i ll f Pi i f lt ) th Lower Pineios River flows between banks and on a bed composed of sediment that is blocks in the study area including the Gastouni graben (hangingwall of Pineios fault zone), the uplifted area of Varda (footwall of Pineios fault zone) and the Kyllini horst transported by the river and is very sensitive to changes of the valley floor slope. Therefore, the i ti t t i f th td d i ll Pi i f lt tt uplifted area of Varda (footwall of Pineios fault zone) and the Kyllini horst. on going active tectonics of the study area and especially Pineios fault zone causes pattern change The most significant pattern change in Lower Pineios River due to the active tectonics change. The most significant pattern change in Lower Pineios River due to the active tectonics of the area is the change of the valley floor slope as it is shown in the above longitudinal of the area is the change of the valley floor slope as it is shown in the above longitudinal profile, the abandonment of its former northward courses and canals and the southward diversion. In order to determine whether or not 3a 3b In order to determine whether or not progradation or retrogradation took place in 6 3a 3b progradation or retrogradation took place in Pineios former and current deltas in recent years, 6 we initially mapped the shorelines at different times in the 27-year-period from 1972 to 1999 using (a) topographic maps at 1:5 000 scale using (a) topographic maps at 1:5.000 scale (1972) (b) aerial photos (1987 1996) (c) (1972), (b) aerial photos (1987 , 1996), (c) satellite images (1999). Then, these data were compared with the present shoreline (2011), which was traced with the use of real-time ki ti diff ti l GPS kinematic differential GPS. Our results have shown that both the former and the current delta fronts of Pineios River are divided into various sub-areas characterized by different type, phase and rate of shoreline displacement. Moreover, there is no systematic progradation or retrogradation in these delta fronts according to the data covering the last 40 year period from 1972 to 2011 delta fronts according to the data covering the last 40-year-period from 1972 to 2011. 3 3d 7 3c 3d 7 In order to determine the effect of the ongoing active tectonics on the Pineios River di i d i th lt 18 th th l 19 th t l ltd l ti lift t f diversion during the late 18 th or the early 19 th century, we calculated relative uplift rates for several sites of the study area based on 230 Th/ 238 U dating of corals made by Stamatopulos et al several sites of the study area based on 230 Th/ 238 U dating of corals made by Stamatopulos et al. (1988 Geogr Fis Din Quat 11) and dating of marine deposits in Kyllini peninsula estimated (1988, Geogr . Fis. Din. Quat. , 11) and dating of marine deposits in Kyllini peninsula estimated by Mariolakos et al. (1988, Research project of the University of Athens): Shoreline displacements in the study area during the last 8 kyrs are always related to the a. 0,39 mm/yr for Psari area (103 kyrs) the tectonic instability and the longshore redistribution of sediments from the Pineios delta. (3b) Th l d lt f Pi i Ri d l d N f K lli i i l bf d b. 0,50 mm/yr for Neapoli area (118 kyrs) 0 67 / f Al t ik (209 k ) (3b) The palaeo-delta of Pineios River was developed N of Kyllini peninsula before and during Neolithic period The Neolithic and Helladic shoreline was located 3 5 km onshore from c. 0,67 mm/yr for Aletreika area (209 kyrs) d 0 16 to 0 48 mm/yr for the eastern (inland) part of Kyllini peninsula (125 kyrs) during Neolithic period. The Neolithic and Helladic shoreline was located 3,5 km onshore from the present shoreline. d. 0,16 to 0,48 mm/yr for the eastern (inland) part of Kyllini peninsula (125 kyrs) the present shoreline. (3c) During the Roman period, Pineios River flowed directly S of the Kotychi lagoon We concluded that: forming a levee, which is now abandoned, eroded and stands as a low sea cliff. An acceleration a. The maximum relative uplift rate (0,67 mm/yr) characterizes an area (Aletreika) located on h f ll d d l h of coastal deposition and consequently delta propagation took place. The Roman shoreline was 1 5 km seaward from the present shoreline the footwall side and very close to the Pineios FZ. b The relative uplift rate of the Gastouni graben (hangingwall of Pineios FZ 0 19 mm/yr) is 1,5 km seaward from the present shoreline. (3d) During the Othoman period Pineios occupied the channel 5 km S of Kotychi lagoon Subsidence Relative uplift rates (in mm/yr) during the last 100 kyrs b. The relative uplift rate of the Gastouni graben (hangingwall of Pineios FZ, 0,19 mm/yr) is less even than the lowest value of the Pineios FZ footwall relative uplift rate (0 39 mm/yr) (3d) During the Othoman period, Pineios occupied the channel 5 km S of Kotychi lagoon forming another levee standing well above the floodplain at the shoreline and indicating coastal Subsidence Relative uplift rates (in mm/yr) during the last 100 kyrs less even than the lowest value of the Pineios FZ footwall relative uplift rate (0,39 mm/yr). c. The northeastern part of Kyllini peninsula has higher relative uplift rate (0,48 mm/yr) than forming another levee standing well above the floodplain at the shoreline and indicating coastal retreat. This channel is now in the process of filling. The minimum age of this levee is about the southeastern part (0,30 mm/yr) 200 yrs BP . The shore has retreated since Roman times. Th Pi i di i t th th f K lli i i l t k l d i th lt 18 th 0,16 - 0,19 0,1901 - 0,39 0,3901 - 0,50 0,5001 - 0,67 d. The maximum relative uplift rate of the footwall of Pineios FZ is significantly higher than th i l ti t f th t t f K lli i i l d th G t i b The Pineios diversion to the south of Kyllini peninsula took place during the late 18 th century Following this diversion the pre 18 th century A D Pineios River delta shoreline in now 0,16 0,19 0,1901 0,39 0,3901 0,50 0,5001 0,67 CONCLUSIONS the maximum relative rates of the eastern part of Kyllini peninsula and the Gastouni graben. century . Following this diversion, the pre-18 th -century- A.D. Pineios River delta shoreline in now undergoing marine transgression and intense coastal erosion as is to be expected in a former The study area is undergoing intense and differential tectonic deformation which has i d i Pli It is obvious that the western part of Pineios drainage basin is developed in an area undergoing marine transgression and intense coastal erosion, as is to be expected in a former delta now essentially starved of new sediment. The pre-18 th -century- A.D. northern channels of continued since Pliocene. It is obvious that the western part of Pineios drainage basin is developed in an area (Gastouni graben), which is uplifted with lower relative uplift rate in comparison with the other Pineios River and few smaller streams can still be seen in their courses to the northwest, now The areas of maximum thickness are constantly subsiding during the sedimentation surrounding areas. Hence, the Lower Pineios River was and is forced to flow in this graben, dry . The dominant geomorphic processes in the modern delta of Pineios River have been d ti d d ti ith l l f i di t The areas of maximum thickness are constantly subsiding during the sedimentation phase and strictly related to the Pineios delta and river sediment loads and transport. Moreover, close and parallel to Pineios FZ. Furthermore the age of Pineios FZ initiation progressively decreases from E to W A progradation and aggradation with large volumes of river sediment. the southern area presents higher subsidence rates than the northern one. Furthermore, the age of Pineios FZ initiation progressively decreases from E to W . A similar decrease from E to W is also observed in the throw of Pineios FZ The throw of the Based on the palaeogeographic reconstructions developed by Kraft et al. (2005, Hesperia Th td i l di id d t th b th t lift ith diff t t (i) th similar decrease from E to W is also observed in the throw of Pineios FZ. The throw of the western part was gradually increased until a critical point in time (probably during 18 th century Based on the palaeogeographic reconstructions developed by Kraft et al. (2005, Hesperia 74) and the late Holocene environmental changes from Kotychi Lagoon recorded by The study area is also divided to three subareas that uplift with different rates: (i) the footwall of Pineios fault zone (0 39-0 67 mm/yr) (ii) the Gastouni graben (0 19 mm/yr) (iii) the western part was gradually increased until a critical point in time (probably during 18 century A.D.) when the relative uplift rate of the Pineios FZ footwall was larger than the relative uplift Kontopoulos and Koutsios (2010, Quatern. Int., 225) we concluded that: h h l h dl d d b k h h d footwall of Pineios fault zone (0,39-0,67 mm/yr), (ii) the Gastouni graben (0,19 mm/yr), (iii) the eastern (inland) part of Kyllini peninsula (0,36-0,48 mm/yr). rate of the hangingwall. Since then, Pineios River was blocked, not able to flow N-wards and h hl f d b h f l d l f d hif S a. the shoreline in the Pineios delta advanced by 3,5 km into the sea in the 6.350 yrs period from Neolithic (8 500 yrs BP) to Roman (2 150 yrs BP) period eastern (inland) part of Kyllini peninsula (0,36 0,48 mm/yr). over the morphology escarpment formed by the fault and consequently enforced to shift S- wards Moreover the combined uplift movement of the footwall of Pineios FZ in the E and the from Neolithic (8.500 yrs BP) to Roman (2.150 yrs BP) period. b the shoreline in the Pineios delta retreated by 1 75 km in the 2 150 yrs period from Roman The western part of Pineios basin is corresponding to the subarea with the lowest wards. Moreover, the combined uplift movement of the footwall of Pineios FZ in the E and the northeastern (inland) part of the Kyllini peninsula in the W resulted in the slightly uplifted b. the shoreline in the Pineios delta retreated by 1, 75 km in the 2.150 yrs period from Roman period (2.150 yrs BP) to present. relative uplift rate (0,19 mm/yr, Gastouni graben). northeastern (inland) part of the Kyllini peninsula in the W resulted in the slightly uplifted margin of the northwestern part of Gastouni graben, the block of the northwards flow of Pineios The diversion of Pineios River to the south of Kyllini peninsula during the 18 th century is a River and the initiation of the southwards flow of the river. Based on the previous shoreline displacements we estimated: tl d ti t 0 55 / f N lithi t R id d The diversion of Pineios River to the south of Kyllini peninsula during the 18 century is a case of fluvial antecedence upon the slightly uplifted margin of the Gastouni graben and is the This natural trend of Pineios southward diversion during 18 th century was supported and f d b th h ti it i th td d i ll b th t ti f th c. a coastal progradation rate as 0,55 m/yr from Neolithic to Roman period and d a coastal retrogradation rate as 0 81 m/yr from Roman period to present result of the gradually increase of the throw along the western part of the Pineios fault zone enforced by the human activity in the study area and especially by the construction of the ancient retaining wall of Pineios River (Papaconstantinou 1991 First International Symposium d. a coastal retrogradation rate as 0,81 m/yr from Roman period to present. during historic times marked by strong and destructive earthquakes during the late 18 th or early 19 th t A D Thi t l d t d i td d f d b th h ancient retaining wall of Pineios River (Papaconstantinou, 1991, First International Symposium on Achaia and Elis in Antiquity, Athens, Greece) during the Hellenistic period (2.330-2.150 B.C. ) 19 th century A.D. This natural process and trend is supported and enforced by the human activity in the study area during historic times as it is revealed by significant human on Achaia and Elis in Antiquity, Athens, Greece) during the Hellenistic period (2.330 2.150 B.C. ) in order to protect the northern banks from the destructive river action. Geomorphology 2011 Athens, June 1-4 activity in the study area during historic times as it is revealed by significant human constructions in the area Fluvial and coastal systems in tectonic active areas constructions in the area.
Transcript of Shoreline displacement drainage diversion in NW...
Shoreline displacement drainage diversion in NW Peloponnese (Greece)Shoreline displacement, drainage diversion in NW Peloponnese (Greece) p g p ( )as result of the geology active tectonics and human activityas result of the geology, active tectonics and human activity as esu o e geo ogy, ac e ec o cs a d u a ac y
d i th l t 100kduring the last 100kyduring the last 100kyFOUNTOULIS I MAVROULIS S VASSILAKIS EFOUNTOULIS I., MAVROULIS S., VASSILAKIS E., ,
National and Kapodistrian University of Athens Faculty of Geology and GeoenvironmentNational and Kapodistrian University of Athens, Faculty of Geology and GeoenvironmentD f D i T i d A li d G lDepartment of Dynamic Tectonic and Applied Geologyp y pp gy
Panepistimiopoli Zografou 15784 Athens email: fountoulis@geol uoa gr smavroulis@yahoo gr evasilak@geol uoa grPanepistimiopoli, Zografou 15784 Athens, email: [email protected], [email protected], [email protected]
ABSTRACTdPineios River is the 3rd longer river in Peloponnese and flows in Kyllini wider area which is located close to the Hellenic Arc system and is one of the most active areas in Greece with a great number of changes in the morphogenetic procedures taking place during the neotectonic period, as well as the last 100ky.
Pineios River downstream crosses the study area and today flows out south of the Kyllini peninsula in the Ionian Sea The Greek historian geographer and philosopher Strabo reported in his Geography (1st century A D VIII 3 5 1) that the mouth of Pineios River was situated during the ancient times to thePineios River downstream crosses the study area and today flows out south of the Kyllini peninsula, in the Ionian Sea. The Greek historian, geographer and philosopher Strabo reported in his Geography (1st century A.D. – VIII, 3,5,1) that the mouth of Pineios River was situated during the ancient times to thenorth of the Kyllini peninsula and the river flowed out into the Ionian Sea southwest of the Kotichi Lagoon. Furthermore, already published data indicate that the Pineios River may have shifted north and south of the Kyllini peninsula throughout the Holocene, it was diverted southwards in the late the 18th centurynorth of the Kyllini peninsula and the river flowed out into the Ionian Sea southwest of the Kotichi Lagoon. Furthermore, already published data indicate that the Pineios River may have shifted north and south of the Kyllini peninsula throughout the Holocene, it was diverted southwards in the late the 18 centuryA.D. and the current delta has been evolving since then. The effects of the geological, tectonic and neotectonic structure and the impact of the human presence and activity on the drainage network are presented here in order to determine the causes of the diversion of the Pineios River and the shorelinedisplacements. For this reason, we used, analyzed and evaluated (a) geomorphological, geological, tectonic and neotectonic data of the study area, (b) historical information and archaeological findings from buried and eroded archaeological sites of the wider study area, (c) published data related to drill cores and
di b d t d (d) t llit d i l h t f diff t i d ll l ti ki ti diff ti l GPS t f th d fi iti f th t h li li It i l d d th t th t di d h li di l t d d i di i th lt f th bi ti f ti t t iradiocarbon dates and (d) satellite and aerial photos of different periods, as well as real-time kinematic differential GPS measurements for the definition of the current shorelineline. It is concluded that the studied shoreline displacements and drainage diversions are the result of the combination of active tectonicsand human activity during the last 100 kyrsand human activity during the last 100 kyrs.
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2Pi i FZ i f th t tl ti t t i NW P l (M li t l 2010 11th IAEG C A kl d N Z l d) It i l t d SSW f Sk li Mt t di E W
1Pineios FZ is one of the most recently active structures in NW Peloponnese (Mavroulis et al., 2010, 11th IAEG Congress, Auckland, New Zealand). It is located SSW of Skolis Mt, trending E-W,
dipping S wards and displaces a Tyrrhenian marine terrace forming well preserved fault scarps and consecutive triangular facets across active hill front The minimum fault slip rate based on thedipping S-wards and displaces a Tyrrhenian marine terrace forming well-preserved fault scarps and consecutive triangular facets across active hill front. The minimum fault slip rate based on thebasal facet height was calculated as 0,15 mm/yr, while the maximum slip rate based on the maximum throw of the fault zone was calculated as 0,48 mm/yr (Mavroulis, et al., 2010). The calculatedbasal facet height was calculated as 0,15 mm/yr, while the maximum slip rate based on the maximum throw of the fault zone was calculated as 0,48 mm/yr (Mavroulis, et al., 2010). The calculatedslip rates of Pineios FZ do not differ substantially from the slip rates in other neotectonic macrostructures of Peloponnese obtained by Koukouvelas et al. (1996, J. Geol. Soc. London, 153) and
The Pineios River development and history takes place in one of the most tectonicallyp y p p y ( , , )
Papanikolaou et al. (2007, Quatern. Int. 171-172).and seismically active areas in Greece. The intense tectonic activity in the area is due to itsl ti th t l t f th H ll i d l t th t b d h
One of the most characteristic effects of the Pineios FZ on the Pineios drainage network is the asymmetrical development of the western part of the Pineios drainage basin, where the Lower(alluvial) Pineios River shifts northwards and flows close and parallel to the northern drainage divide which is formed and determined by the Pineios FZ This asymmetry is clearly reflected in thelocation on the external part of the Hellenic arc and close to the convergent boundary where
African plate is subducted beneath the European one as well as the diapirism of the evaporates(alluvial) Pineios River shifts northwards and flows close and parallel to the northern drainage divide, which is formed and determined by the Pineios FZ. This asymmetry is clearly reflected in thenumber size and order of the tributaries and subbasins on either side of the main river Especially north of the Lower Pineios River the 1st and 2nd order drainage basins prevail while higher orderAfrican plate is subducted beneath the European one as well as the diapirism of the evaporates.
The recorded highest seismicity levels in Greece (Hatzfeld et al., 1990, Geophys. J. Int., 101) asnumber, size and order of the tributaries and subbasins on either side of the main river. Especially, north of the Lower Pineios River, the 1 and 2 order drainage basins prevail, while higher orderdrainage basins are absent. In contradiction, the 3rd order drainage basins prevail covering an extended area south of the Lower Pineios River.The recorded highest seismicity levels in Greece (Hatzfeld et al., 1990, Geophys. J. Int., 101) as
well as the generation of many strong earthquakes confirm the neotectonic studies, which showdrainage basins are absent. In contradiction, the 3 order drainage basins prevail covering an extended area south of the Lower Pineios River.
g y g q ,that the area is undergoing intense tectonic deformation.
4 5The main neotectonic macrostructures of the wider study area are (a) the ErymanthosMts horst (b) the Pyrgos Olympia basin and (c) the Kyllini horst These structures result from
4 5Mts horst, (b) the Pyrgos - Olympia basin and (c) the Kyllini horst. These structures result fromongoing vertical movements and are faulted and/or bounded by fault zonesongoing vertical movements and are faulted and/or bounded by fault zones.
The geological formations can be divided into alpine and post-alpine. The alpinee geo og ca o at o s ca be d ded to a p e a d post a p e e a p eformations belong to Pindos, Gavrovo - Tripolis and Ionian units. The post - alpine formationsbelong to the Pyrgos - Olympia basin, are of Pliocene and Quaternary age and lie
f bl th l i b t Th i hi l di t ib ti d th i t f f iunconformably on the alpine basement. Their geographical distribution and the variety of facies(marine lagoonal lacustrine and terrestrial) clearly reflect vertical movements during the(marine, lagoonal, lacustrine and terrestrial) clearly reflect vertical movements during theneotectonic period and ongoing active tectonicsneotectonic period and ongoing active tectonics.
The most important fault zones in the study area are the Panopoulo fault zonep y p(Panopoulo FZ), Pineios fault zone (Pineios FZ) and the strike - slip fault zone that gave rise tothe Andravida earthquake (08-06-2008, ML=6,5). These major faults form several neotectonicbl k i th t d i l di th G t i b (h i ll f Pi i f lt ) th
Lower Pineios River flows between banks and on a bed composed of sediment that isblocks in the study area including the Gastouni graben (hangingwall of Pineios fault zone), theuplifted area of Varda (footwall of Pineios fault zone) and the Kyllini horst
transported by the river and is very sensitive to changes of the valley floor slope. Therefore, thei ti t t i f th t d d i ll Pi i f lt ttuplifted area of Varda (footwall of Pineios fault zone) and the Kyllini horst. on going active tectonics of the study area and especially Pineios fault zone causes pattern
change The most significant pattern change in Lower Pineios River due to the active tectonicschange. The most significant pattern change in Lower Pineios River due to the active tectonicsof the area is the change of the valley floor slope as it is shown in the above longitudinalof the area is the change of the valley floor slope as it is shown in the above longitudinalprofile, the abandonment of its former northward courses and canals and the southwardp ,diversion.
In order to determine whether or not
3a 3bIn order to determine whether or not
progradation or retrogradation took place in63a 3b progradation or retrogradation took place inPineios former and current deltas in recent years,6 y ,we initially mapped the shorelines at differenttimes in the 27-year-period from 1972 to 1999using (a) topographic maps at 1:5 000 scaleusing (a) topographic maps at 1:5.000 scale(1972) (b) aerial photos (1987 1996) (c)(1972), (b) aerial photos (1987, 1996), (c)satellite images (1999). Then, these data weresate te ages ( 999) e , t ese data e ecompared with the present shoreline (2011),which was traced with the use of real-timeki ti diff ti l GPSkinematic differential GPS.
Our results have shown that both the former and the current delta fronts of PineiosRiver are divided into various sub-areas characterized by different type, phase and rate ofshoreline displacement. Moreover, there is no systematic progradation or retrogradation in thesedelta fronts according to the data covering the last 40 year period from 1972 to 2011delta fronts according to the data covering the last 40-year-period from 1972 to 2011.
3 3d 73c 3d 7
In order to determine the effect of the ongoing active tectonics on the Pineios Riverdi i d i th l t 18th th l 19th t l l t d l ti lift t fdiversion during the late 18th or the early 19th century, we calculated relative uplift rates forseveral sites of the study area based on 230Th/238U dating of corals made by Stamatopulos et alseveral sites of the study area based on 230Th/238U dating of corals made by Stamatopulos et al.(1988 Geogr Fis Din Quat 11) and dating of marine deposits in Kyllini peninsula estimated(1988, Geogr. Fis. Din. Quat., 11) and dating of marine deposits in Kyllini peninsula estimatedby Mariolakos et al. (1988, Research project of the University of Athens):Shoreline displacements in the study area during the last 8 kyrs are always related to the y ( , p j y )a. 0,39 mm/yr for Psari area (103 kyrs)the tectonic instability and the longshore redistribution of sediments from the Pineios delta.
(3b) Th l d lt f Pi i Ri d l d N f K lli i i l b f d b. 0,50 mm/yr for Neapoli area (118 kyrs)0 67 / f Al t ik (209 k )
(3b) The palaeo-delta of Pineios River was developed N of Kyllini peninsula before andduring Neolithic period The Neolithic and Helladic shoreline was located 3 5 km onshore from c. 0,67 mm/yr for Aletreika area (209 kyrs)
d 0 16 to 0 48 mm/yr for the eastern (inland) part of Kyllini peninsula (125 kyrs)during Neolithic period. The Neolithic and Helladic shoreline was located 3,5 km onshore fromthe present shoreline. d. 0,16 to 0,48 mm/yr for the eastern (inland) part of Kyllini peninsula (125 kyrs)the present shoreline.
(3c) During the Roman period, Pineios River flowed directly S of the Kotychi lagoonWe concluded that:
( ) g p , y y gforming a levee, which is now abandoned, eroded and stands as a low sea cliff. An acceleration
a. The maximum relative uplift rate (0,67 mm/yr) characterizes an area (Aletreika) located onh f ll d d l h
of coastal deposition and consequently delta propagation took place. The Roman shoreline was1 5 km seaward from the present shoreline the footwall side and very close to the Pineios FZ.
b The relative uplift rate of the Gastouni graben (hangingwall of Pineios FZ 0 19 mm/yr) is1,5 km seaward from the present shoreline.
(3d) During the Othoman period Pineios occupied the channel 5 km S of Kotychi lagoon SubsidenceRelative uplift rates (in mm/yr) during the last 100 kyrsb. The relative uplift rate of the Gastouni graben (hangingwall of Pineios FZ, 0,19 mm/yr) isless even than the lowest value of the Pineios FZ footwall relative uplift rate (0 39 mm/yr)
(3d) During the Othoman period, Pineios occupied the channel 5 km S of Kotychi lagoonforming another levee standing well above the floodplain at the shoreline and indicating coastal
Subsidence Relative uplift rates (in mm/yr) during the last 100 kyrs
less even than the lowest value of the Pineios FZ footwall relative uplift rate (0,39 mm/yr).c. The northeastern part of Kyllini peninsula has higher relative uplift rate (0,48 mm/yr) than
forming another levee standing well above the floodplain at the shoreline and indicating coastalretreat. This channel is now in the process of filling. The minimum age of this levee is about p y p g p ( , /y )
the southeastern part (0,30 mm/yr)200 yrs BP. The shore has retreated since Roman times.Th Pi i di i t th th f K lli i i l t k l d i th l t 18th 0,16 - 0,19 0,1901 - 0,39 0,3901 - 0,50 0,5001 - 0,67
d. The maximum relative uplift rate of the footwall of Pineios FZ is significantly higher thanth i l ti t f th t t f K lli i i l d th G t i b
The Pineios diversion to the south of Kyllini peninsula took place during the late 18th
century Following this diversion the pre 18th century A D Pineios River delta shoreline in now
0,16 0,19 0,1901 0,39 0,3901 0,50 0,5001 0,67
CONCLUSIONSthe maximum relative rates of the eastern part of Kyllini peninsula and the Gastouni graben.century. Following this diversion, the pre-18th-century-A.D. Pineios River delta shoreline in nowundergoing marine transgression and intense coastal erosion as is to be expected in a former
The study area is undergoing intense and differential tectonic deformation which hasi d i PliIt is obvious that the western part of Pineios drainage basin is developed in an area
undergoing marine transgression and intense coastal erosion, as is to be expected in a formerdelta now essentially starved of new sediment. The pre-18th-century-A.D. northern channels of
continued since Pliocene.It is obvious that the western part of Pineios drainage basin is developed in an area(Gastouni graben), which is uplifted with lower relative uplift rate in comparison with the other
y p yPineios River and few smaller streams can still be seen in their courses to the northwest, now
The areas of maximum thickness are constantly subsiding during the sedimentation
( g ), p p psurrounding areas. Hence, the Lower Pineios River was and is forced to flow in this graben,dry. The dominant geomorphic processes in the modern delta of Pineios River have been
d ti d d ti ith l l f i di t The areas of maximum thickness are constantly subsiding during the sedimentationphase and strictly related to the Pineios delta and river sediment loads and transport. Moreover,close and parallel to Pineios FZ.
Furthermore the age of Pineios FZ initiation progressively decreases from E to W Aprogradation and aggradation with large volumes of river sediment.
p y p ,the southern area presents higher subsidence rates than the northern one.Furthermore, the age of Pineios FZ initiation progressively decreases from E to W. A
similar decrease from E to W is also observed in the throw of Pineios FZ The throw of theBased on the palaeogeographic reconstructions developed by Kraft et al. (2005, Hesperia
Th t d i l di id d t th b th t lift ith diff t t (i) th
similar decrease from E to W is also observed in the throw of Pineios FZ. The throw of thewestern part was gradually increased until a critical point in time (probably during 18th century
Based on the palaeogeographic reconstructions developed by Kraft et al. (2005, Hesperia74) and the late Holocene environmental changes from Kotychi Lagoon recorded by
The study area is also divided to three subareas that uplift with different rates: (i) thefootwall of Pineios fault zone (0 39-0 67 mm/yr) (ii) the Gastouni graben (0 19 mm/yr) (iii) the
western part was gradually increased until a critical point in time (probably during 18 centuryA.D.) when the relative uplift rate of the Pineios FZ footwall was larger than the relative uplift
) g y g yKontopoulos and Koutsios (2010, Quatern. Int., 225) we concluded that:
h h l h d l d d b k h h d footwall of Pineios fault zone (0,39-0,67 mm/yr), (ii) the Gastouni graben (0,19 mm/yr), (iii) theeastern (inland) part of Kyllini peninsula (0,36-0,48 mm/yr).rate of the hangingwall. Since then, Pineios River was blocked, not able to flow N-wards and
h h l f d b h f l d l f d hif Sa. the shoreline in the Pineios delta advanced by 3,5 km into the sea in the 6.350 yrs period
from Neolithic (8 500 yrs BP) to Roman (2 150 yrs BP) period eastern (inland) part of Kyllini peninsula (0,36 0,48 mm/yr).over the morphology escarpment formed by the fault and consequently enforced to shift S-wards Moreover the combined uplift movement of the footwall of Pineios FZ in the E and the
from Neolithic (8.500 yrs BP) to Roman (2.150 yrs BP) period.b the shoreline in the Pineios delta retreated by 1 75 km in the 2 150 yrs period from Roman
The western part of Pineios basin is corresponding to the subarea with the lowestwards. Moreover, the combined uplift movement of the footwall of Pineios FZ in the E and thenortheastern (inland) part of the Kyllini peninsula in the W resulted in the slightly uplifted
b. the shoreline in the Pineios delta retreated by 1,75 km in the 2.150 yrs period from Romanperiod (2.150 yrs BP) to present.
relative uplift rate (0,19 mm/yr, Gastouni graben).northeastern (inland) part of the Kyllini peninsula in the W resulted in the slightly upliftedmargin of the northwestern part of Gastouni graben, the block of the northwards flow of Pineios
p ( y ) p
The diversion of Pineios River to the south of Kyllini peninsula during the 18th century is a
g p g ,River and the initiation of the southwards flow of the river.Based on the previous shoreline displacements we estimated:
t l d ti t 0 55 / f N lithi t R i d d The diversion of Pineios River to the south of Kyllini peninsula during the 18 century is acase of fluvial antecedence upon the slightly uplifted margin of the Gastouni graben and is theThis natural trend of Pineios southward diversion during 18th century was supported and
f d b th h ti it i th t d d i ll b th t ti f thc. a coastal progradation rate as 0,55 m/yr from Neolithic to Roman period andd a coastal retrogradation rate as 0 81 m/yr from Roman period to present case o u a a tecede ce upo t e s g t y up ted a g o t e Gastou g abe a d s t e
result of the gradually increase of the throw along the western part of the Pineios fault zoneenforced by the human activity in the study area and especially by the construction of theancient retaining wall of Pineios River (Papaconstantinou 1991 First International Symposium
d. a coastal retrogradation rate as 0,81 m/yr from Roman period to present.
during historic times marked by strong and destructive earthquakes during the late 18th or early19th t A D Thi t l d t d i t d d f d b th h
ancient retaining wall of Pineios River (Papaconstantinou, 1991, First International Symposiumon Achaia and Elis in Antiquity, Athens, Greece) during the Hellenistic period (2.330-2.150 B.C.) 19th century A.D. This natural process and trend is supported and enforced by the human
activity in the study area during historic times as it is revealed by significant human
on Achaia and Elis in Antiquity, Athens, Greece) during the Hellenistic period (2.330 2.150 B.C.)in order to protect the northern banks from the destructive river action.Geomorphology 2011 Athens, June 1-4
activity in the study area during historic times as it is revealed by significant humanconstructions in the area
pp gyFluvial and coastal systems in tectonic active areas constructions in the area.y
