This study investigates the possibility of Holocene glaciation on Mount Olympus (Greece) with a r... more This study investigates the possibility of Holocene glaciation on Mount Olympus (Greece) with a respective local temperature–precipitation equilibrium line altitude (TP-ELA) at c. 2200 m a.s.l., based on geomorphologic and paleoclimatic evidence. At present, the local TP-ELA is situated above the mountain’s summit (c. 2918 m a.s.l.), but permanent snowfields and ice bodies survive within Megala Kazania cirque between c. 2400 and c. 2300 m a.s.l., because of the cirque’s maritime setting that results from its close proximity (c. 18 km) to the Aegean Sea and of the local topographical controls. The snow and ice bodies occupied a considerably larger area and attained a stabilization phase between AD 1960 and 1980, also manifested from aerial photographs, a period characterized by increased winter precipitation (Pw) with subsequent TP-ELA depression to c. 2410 m a.s.l. Mid- to late-20thcentury Pw and TP-ELA variations exhibit negative correlations with the winter North Atlantic Oscillation index (NAOw) at annual and multidecadal (30 years) timescales. Late Holocene (AD 1680–1860) reconstructed summer mean temperatures were lower by Ts < 1.1°C in relation to the reference period between AD 1960 and 1980 and were also superimposed to negative NAOw phases, thus bracketing this time interval as a favorable one to glacial formation and/or advance. Millennial-scale annual precipitation reconstructions at the hypothesized TP-ELA (c. 2200 m a.s.l.) point the period between 8 and 4 kyr BP as another glacier-friendly candidate. The mid-Holocene rather simplistic sequence of potential glacial advance phase was disturbed by short-lived cold climatic deteriorations, well-documented over the northern Aegean region that may partly explain the multicrested shape of the highest (c. 2200 m a.s.l.) morainic complex of Megala Kazania cirque.
Using in-situ 36Cl cosmogenic exposure dating, we determine the earthquake slip release pattern o... more Using in-situ 36Cl cosmogenic exposure dating, we determine the earthquake slip release pattern over the last~ 14 kyrs along one of the major active normal fault systems in Central Italy. The~ 40 km-long Velino-Magnola fault (VMF) is located~ 20 km SW from the epicenter of the devastating April 2009 l'Aquila earthquake. We sampled the VMF at five well-separated sites along its length, and modeled the 36Cl concentrations measured in the 400 samples (Schlagenhauf et al. 2010). We find that the fault has broken in large earthquakes ...
ABSTRACT Chlorine-36 is a cosmogenic nuclide mainly produced in the atmosphere by interactions be... more ABSTRACT Chlorine-36 is a cosmogenic nuclide mainly produced in the atmosphere by interactions between energetic particles originating from the cosmic radiations and 40Ar. Because of its long half-life (T1-2 = 3.01 105 yr) and its high mobility, chlorine-36 is a critical radionuclide concerning radioactive waste repository sites. Moreover, it has been shown that inorganic chlorine could be enriched along the trophic chain due to its high solubility and bioavailability (Ashworth and Shaw, 2006). Additionally, many studies during the last decades have established that due to chlorination process, organic chlorine may account for a large proportion of the total soil chlorine pool (more than 80 % in surface soils of temperate ecosystems. Redon et al., 2012). The aim of this study is thus to measure chlorine-36 in all the compartments of the biogeochemical cycle, to better understand its recycling in the biosphere. The study site is the experimental beech forest site of the Andra long-term monitoring and testing system (OPE*). It is located at Montiers-sur-Saulx, North-East of France and is associated to the future radioactive waste repository site of Bure. Since March 2012, rainwater above (rainfall collected from a 45 m high tower built on purpose) and below (throughfall and stemflow) the canopy, has been collected monthly, as well as soil solutions (gravitational and bound waters) at four depths (0, 10, 30, 60 cm deep). Chlorine-36 and chlorine have been measured in the rainfall samples between March and July 2012 and in water solutions collected from all compartments of the biosphere using isotope dilution mass spectrometry at the french AMS national facility ASTER located at CEREGE. The results yielded from the rainfall samples allow to study the temporal fluctuations of chlorine-36 in the atmosphere, which represents the main inflow of chlorine-36 in its biogeochemical cycle. The first results indicate a flow increase during the late spring-early summer. Santos et al., 2004 have also observed a similar pattern in southern Spain. This increase might be due to a tropopause break, a natural process which occurs in spring and in fall. This break implies an increase of the air masses exchange between the tropopause and the stratosphere and therefore could cause high chlorine-36 inflow. All together, those results allow to draw a profile of the evolution of chlorine-36 concentrations in the various pools of the biogeochemical cycle (from the upper rainfall through stemflow and throughfall to the lower soil). Both 36Cl and Cl concentrations in stemflow samples are 25-50% higher than in the rainfall and throughfall samples. In water solutions collected from the soil, chlorine-36 concentrations vary between 3 to 8 10 3 at/ml, with an increase in the concentration at 30 cm depth. To understand the chlorine-36 recycling in soil, the next step will be to isolate and measure the 36Cl concentrations in the inorganic and organic fractions of chlorine in a soil profile. * : OPE : Observatoire Pérenne de l&#39;Environnement (SOERE), French national long-term monitoring and experimental system for research in environment, www.andra-ope.fr Ashworth, D. J. and Shaw, G. (2006). A comparison of the soil migration and plant uptake of radioactive chlorine and iodine from contaminated groundwater. Journal of environmental radioactivity, 89(1) :61-80. Redon, P.-O., Jolivet, C., Saby, N. P. a., Abdelouas, A., and Thiry, Y. (2012). Occurrence of natural organic chlorine in soils for different land uses. Biogeochemistry (In press), doi : 10.1007/s10533- 012-9771-7. Santos, F., Lopez-Gutierrez, J., Garcia-Leon, M., Schnabel, C., Synal, H., and Suter, M. (2004). Analysis of 36Cl in atmospheric samples from Seville (Spain) by AMS. Nuclear Instruments and Methods in Physics Research Section B : Beam Interactions with Materials and Atoms, 223-224 :501-506.
ABSTRACT Located in central Europe between the southern Alps and the Dinarides, the≈ 100km long I... more ABSTRACT Located in central Europe between the southern Alps and the Dinarides, the≈ 100km long Idrija fault, striking N310 and dipping ≈ 80°NE is often considered as the potential source of the 1511 earthquake (estimated magnitude: 6.9). However, although continental earthquakes of similar size are almost invariably associated with surface faulting, no surface traces have been found. In Europe identifying the faults capable of producing large earthquakes is difficult due to dense vegetation covering their trace and strong anthropization and erosion smoothing it. This is particularly true in Slovenia where no detailed map of the active faults is available and where the amount of deformation absorbed in this region is unknown. Those are, however, a prerequisite to estimate the expected magnitude of future large events and slip rates. Using detailed topographical maps, satellite images (SPOT 5), 12.5m illuminated DEM and airborne Lidar data-derived 1m DEM, we examined in detail the Idrija fault trace along a 20 km long transect in the central portion of the fault. Combining those topographical and remote sensing data allow characterizing the recent activity along the Idrija fault and to estimate its cumulative displacement along strike. Between Tolmin and Godovic, the fault trace is mostly rectilinear but appears divided into four disconnected segments of 6-11km long that are right-stepping on the northern portion and left-stepping south, along the mean strike of the fault zone. Morphological evidences such as offset streams and ridges and major drainage abandonment suggest ongoing movement. At four sites along the fault, a quantitative analysis of the offset topography markers based on field observations, Lidar DEM and kinematic GPS-derived DEM allow better constraining the kinematics of the fault (horinzontal and vertical displacements). A cumulative dextral offset comprised between 40 and 60m was measured at most studied sites. We found two larger offsets of ≈ 170 m and ≈ 430m long within the southernmost site. The estimated vertical component is significant since it accounts for about 20-30% of the total fault movement.
ABSTRACT The right lateral transpressive, 200 km long, Sava fault in northern Slovenia is at the ... more ABSTRACT The right lateral transpressive, 200 km long, Sava fault in northern Slovenia is at the eastern part of the Periadriatic fault system. The fault strikes NW-SE to E-W and dips steeply towards the north. Upper Oligocene volcano-clastic rocks are apparently displaced by 25-70 km along strike (Placer, 1996) suggesting a long-term slip-rate between 1 and 5 mm/yr over the last 20 Ma (Jamšek Rupnik et al., 2012). On the other hand, GPS measurements yield a slip-rate of about 1 mm/yr (Vrabec et al., 2006). Moreover, no large earthquakes (M&gt;5) have been reported on this major fault over the last 1000 yrs. To constrain the seismic hazard in this densely populated region of Europe, we studied the western part of the Sava fault between Jesenice and Kamnik to identify geomorphic indicators of its Quaternary activity, to determine the organization and hierarchy of the overall fault network, and to quantitatively constrain the displacement on this portion of the fault. From Jesenice to Preddvor, the NW-striking fault trace is almost rectilinear. Southeastward, the fault splays into multiple E-W striking branches. The fault also appears divided into several disconnected segments that are both right-stepping and left-stepping along the mean strike of the fault zone. These geometrical arrangements suggest that the fault segments west of Preddvor have a vertical component of slip in addition to their dominant right lateral one, while the vertical component appears to be the dominant one southeast. The segments are 3.5 to 15.5 km long and according to scaling laws, they could produce earthquakes with magnitude 5.6 to 6.5. Dextral bending for 1.3 to 5.4 km of all major rivers crossing the fault are evidences of the fault activity over several thousands of years. Changes in river regime with incision north of the fault and active aggradation with inset terrace formation south of it also suggest ongoing vertical displacement which is yet to be quantified. Three sites near Tržič, Preddvor and Kamnik, where the fault trace is particularly sharp, have been investigated in detail. Fluvial terraces appear displaced and on the eastern portion of the fault, near Cerklje several parallel faults segments with a clear reverse component are observed. The southernmost segment offsets vertically the Kokra alluvial fan with a maximum displacement of 5 m. In the future we will date those alluvial surfaces and perform paleoseismological studies. References Jamšek Rupnik, P., Benedetti, L., Bavec, M. and Vrabec, M. 2012. Geomorphic indicators of Quaternary activity of the Sava fault between Golnik and Preddvor. RMZ - Material and Geoenvironment, Vol. 59, No. 2/3, pp. 299-314. Placer, L. 1996. Displacement along the Sava fault. Geologija, Vol. 39, pp. 283-287. Vrabec, M., Pavlovčič Prešeren, P. and Stopar, B. 2006. GPS study (1996-2002) of active deformation along the Periadriatic fault system in northeastern Slovenia: tectonic model. Geologica Carpathica, Vol. 57, No. 1, pp. 57-65.
This study investigates the possibility of Holocene glaciation on Mount Olympus (Greece) with a r... more This study investigates the possibility of Holocene glaciation on Mount Olympus (Greece) with a respective local temperature–precipitation equilibrium line altitude (TP-ELA) at c. 2200 m a.s.l., based on geomorphologic and paleoclimatic evidence. At present, the local TP-ELA is situated above the mountain’s summit (c. 2918 m a.s.l.), but permanent snowfields and ice bodies survive within Megala Kazania cirque between c. 2400 and c. 2300 m a.s.l., because of the cirque’s maritime setting that results from its close proximity (c. 18 km) to the Aegean Sea and of the local topographical controls. The snow and ice bodies occupied a considerably larger area and attained a stabilization phase between AD 1960 and 1980, also manifested from aerial photographs, a period characterized by increased winter precipitation (Pw) with subsequent TP-ELA depression to c. 2410 m a.s.l. Mid- to late-20thcentury Pw and TP-ELA variations exhibit negative correlations with the winter North Atlantic Oscillation index (NAOw) at annual and multidecadal (30 years) timescales. Late Holocene (AD 1680–1860) reconstructed summer mean temperatures were lower by Ts < 1.1°C in relation to the reference period between AD 1960 and 1980 and were also superimposed to negative NAOw phases, thus bracketing this time interval as a favorable one to glacial formation and/or advance. Millennial-scale annual precipitation reconstructions at the hypothesized TP-ELA (c. 2200 m a.s.l.) point the period between 8 and 4 kyr BP as another glacier-friendly candidate. The mid-Holocene rather simplistic sequence of potential glacial advance phase was disturbed by short-lived cold climatic deteriorations, well-documented over the northern Aegean region that may partly explain the multicrested shape of the highest (c. 2200 m a.s.l.) morainic complex of Megala Kazania cirque.
Using in-situ 36Cl cosmogenic exposure dating, we determine the earthquake slip release pattern o... more Using in-situ 36Cl cosmogenic exposure dating, we determine the earthquake slip release pattern over the last~ 14 kyrs along one of the major active normal fault systems in Central Italy. The~ 40 km-long Velino-Magnola fault (VMF) is located~ 20 km SW from the epicenter of the devastating April 2009 l'Aquila earthquake. We sampled the VMF at five well-separated sites along its length, and modeled the 36Cl concentrations measured in the 400 samples (Schlagenhauf et al. 2010). We find that the fault has broken in large earthquakes ...
ABSTRACT Chlorine-36 is a cosmogenic nuclide mainly produced in the atmosphere by interactions be... more ABSTRACT Chlorine-36 is a cosmogenic nuclide mainly produced in the atmosphere by interactions between energetic particles originating from the cosmic radiations and 40Ar. Because of its long half-life (T1-2 = 3.01 105 yr) and its high mobility, chlorine-36 is a critical radionuclide concerning radioactive waste repository sites. Moreover, it has been shown that inorganic chlorine could be enriched along the trophic chain due to its high solubility and bioavailability (Ashworth and Shaw, 2006). Additionally, many studies during the last decades have established that due to chlorination process, organic chlorine may account for a large proportion of the total soil chlorine pool (more than 80 % in surface soils of temperate ecosystems. Redon et al., 2012). The aim of this study is thus to measure chlorine-36 in all the compartments of the biogeochemical cycle, to better understand its recycling in the biosphere. The study site is the experimental beech forest site of the Andra long-term monitoring and testing system (OPE*). It is located at Montiers-sur-Saulx, North-East of France and is associated to the future radioactive waste repository site of Bure. Since March 2012, rainwater above (rainfall collected from a 45 m high tower built on purpose) and below (throughfall and stemflow) the canopy, has been collected monthly, as well as soil solutions (gravitational and bound waters) at four depths (0, 10, 30, 60 cm deep). Chlorine-36 and chlorine have been measured in the rainfall samples between March and July 2012 and in water solutions collected from all compartments of the biosphere using isotope dilution mass spectrometry at the french AMS national facility ASTER located at CEREGE. The results yielded from the rainfall samples allow to study the temporal fluctuations of chlorine-36 in the atmosphere, which represents the main inflow of chlorine-36 in its biogeochemical cycle. The first results indicate a flow increase during the late spring-early summer. Santos et al., 2004 have also observed a similar pattern in southern Spain. This increase might be due to a tropopause break, a natural process which occurs in spring and in fall. This break implies an increase of the air masses exchange between the tropopause and the stratosphere and therefore could cause high chlorine-36 inflow. All together, those results allow to draw a profile of the evolution of chlorine-36 concentrations in the various pools of the biogeochemical cycle (from the upper rainfall through stemflow and throughfall to the lower soil). Both 36Cl and Cl concentrations in stemflow samples are 25-50% higher than in the rainfall and throughfall samples. In water solutions collected from the soil, chlorine-36 concentrations vary between 3 to 8 10 3 at/ml, with an increase in the concentration at 30 cm depth. To understand the chlorine-36 recycling in soil, the next step will be to isolate and measure the 36Cl concentrations in the inorganic and organic fractions of chlorine in a soil profile. * : OPE : Observatoire Pérenne de l&#39;Environnement (SOERE), French national long-term monitoring and experimental system for research in environment, www.andra-ope.fr Ashworth, D. J. and Shaw, G. (2006). A comparison of the soil migration and plant uptake of radioactive chlorine and iodine from contaminated groundwater. Journal of environmental radioactivity, 89(1) :61-80. Redon, P.-O., Jolivet, C., Saby, N. P. a., Abdelouas, A., and Thiry, Y. (2012). Occurrence of natural organic chlorine in soils for different land uses. Biogeochemistry (In press), doi : 10.1007/s10533- 012-9771-7. Santos, F., Lopez-Gutierrez, J., Garcia-Leon, M., Schnabel, C., Synal, H., and Suter, M. (2004). Analysis of 36Cl in atmospheric samples from Seville (Spain) by AMS. Nuclear Instruments and Methods in Physics Research Section B : Beam Interactions with Materials and Atoms, 223-224 :501-506.
ABSTRACT Located in central Europe between the southern Alps and the Dinarides, the≈ 100km long I... more ABSTRACT Located in central Europe between the southern Alps and the Dinarides, the≈ 100km long Idrija fault, striking N310 and dipping ≈ 80°NE is often considered as the potential source of the 1511 earthquake (estimated magnitude: 6.9). However, although continental earthquakes of similar size are almost invariably associated with surface faulting, no surface traces have been found. In Europe identifying the faults capable of producing large earthquakes is difficult due to dense vegetation covering their trace and strong anthropization and erosion smoothing it. This is particularly true in Slovenia where no detailed map of the active faults is available and where the amount of deformation absorbed in this region is unknown. Those are, however, a prerequisite to estimate the expected magnitude of future large events and slip rates. Using detailed topographical maps, satellite images (SPOT 5), 12.5m illuminated DEM and airborne Lidar data-derived 1m DEM, we examined in detail the Idrija fault trace along a 20 km long transect in the central portion of the fault. Combining those topographical and remote sensing data allow characterizing the recent activity along the Idrija fault and to estimate its cumulative displacement along strike. Between Tolmin and Godovic, the fault trace is mostly rectilinear but appears divided into four disconnected segments of 6-11km long that are right-stepping on the northern portion and left-stepping south, along the mean strike of the fault zone. Morphological evidences such as offset streams and ridges and major drainage abandonment suggest ongoing movement. At four sites along the fault, a quantitative analysis of the offset topography markers based on field observations, Lidar DEM and kinematic GPS-derived DEM allow better constraining the kinematics of the fault (horinzontal and vertical displacements). A cumulative dextral offset comprised between 40 and 60m was measured at most studied sites. We found two larger offsets of ≈ 170 m and ≈ 430m long within the southernmost site. The estimated vertical component is significant since it accounts for about 20-30% of the total fault movement.
ABSTRACT The right lateral transpressive, 200 km long, Sava fault in northern Slovenia is at the ... more ABSTRACT The right lateral transpressive, 200 km long, Sava fault in northern Slovenia is at the eastern part of the Periadriatic fault system. The fault strikes NW-SE to E-W and dips steeply towards the north. Upper Oligocene volcano-clastic rocks are apparently displaced by 25-70 km along strike (Placer, 1996) suggesting a long-term slip-rate between 1 and 5 mm/yr over the last 20 Ma (Jamšek Rupnik et al., 2012). On the other hand, GPS measurements yield a slip-rate of about 1 mm/yr (Vrabec et al., 2006). Moreover, no large earthquakes (M&gt;5) have been reported on this major fault over the last 1000 yrs. To constrain the seismic hazard in this densely populated region of Europe, we studied the western part of the Sava fault between Jesenice and Kamnik to identify geomorphic indicators of its Quaternary activity, to determine the organization and hierarchy of the overall fault network, and to quantitatively constrain the displacement on this portion of the fault. From Jesenice to Preddvor, the NW-striking fault trace is almost rectilinear. Southeastward, the fault splays into multiple E-W striking branches. The fault also appears divided into several disconnected segments that are both right-stepping and left-stepping along the mean strike of the fault zone. These geometrical arrangements suggest that the fault segments west of Preddvor have a vertical component of slip in addition to their dominant right lateral one, while the vertical component appears to be the dominant one southeast. The segments are 3.5 to 15.5 km long and according to scaling laws, they could produce earthquakes with magnitude 5.6 to 6.5. Dextral bending for 1.3 to 5.4 km of all major rivers crossing the fault are evidences of the fault activity over several thousands of years. Changes in river regime with incision north of the fault and active aggradation with inset terrace formation south of it also suggest ongoing vertical displacement which is yet to be quantified. Three sites near Tržič, Preddvor and Kamnik, where the fault trace is particularly sharp, have been investigated in detail. Fluvial terraces appear displaced and on the eastern portion of the fault, near Cerklje several parallel faults segments with a clear reverse component are observed. The southernmost segment offsets vertically the Kokra alluvial fan with a maximum displacement of 5 m. In the future we will date those alluvial surfaces and perform paleoseismological studies. References Jamšek Rupnik, P., Benedetti, L., Bavec, M. and Vrabec, M. 2012. Geomorphic indicators of Quaternary activity of the Sava fault between Golnik and Preddvor. RMZ - Material and Geoenvironment, Vol. 59, No. 2/3, pp. 299-314. Placer, L. 1996. Displacement along the Sava fault. Geologija, Vol. 39, pp. 283-287. Vrabec, M., Pavlovčič Prešeren, P. and Stopar, B. 2006. GPS study (1996-2002) of active deformation along the Periadriatic fault system in northeastern Slovenia: tectonic model. Geologica Carpathica, Vol. 57, No. 1, pp. 57-65.
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line altitude (TP-ELA) at c. 2200 m a.s.l., based on geomorphologic and paleoclimatic evidence. At present, the local TP-ELA is situated above the
mountain’s summit (c. 2918 m a.s.l.), but permanent snowfields and ice bodies survive within Megala Kazania cirque between c. 2400 and c. 2300 m a.s.l.,
because of the cirque’s maritime setting that results from its close proximity (c. 18 km) to the Aegean Sea and of the local topographical controls. The
snow and ice bodies occupied a considerably larger area and attained a stabilization phase between AD 1960 and 1980, also manifested from aerial
photographs, a period characterized by increased winter precipitation (Pw) with subsequent TP-ELA depression to c. 2410 m a.s.l. Mid- to late-20thcentury
Pw and TP-ELA variations exhibit negative correlations with the winter North Atlantic Oscillation index (NAOw) at annual and multidecadal
(30 years) timescales. Late Holocene (AD 1680–1860) reconstructed summer mean temperatures were lower by Ts < 1.1°C in relation to the reference
period between AD 1960 and 1980 and were also superimposed to negative NAOw phases, thus bracketing this time interval as a favorable one to glacial
formation and/or advance. Millennial-scale annual precipitation reconstructions at the hypothesized TP-ELA (c. 2200 m a.s.l.) point the period between
8 and 4 kyr BP as another glacier-friendly candidate. The mid-Holocene rather simplistic sequence of potential glacial advance phase was disturbed by
short-lived cold climatic deteriorations, well-documented over the northern Aegean region that may partly explain the multicrested shape of the highest
(c. 2200 m a.s.l.) morainic complex of Megala Kazania cirque.
line altitude (TP-ELA) at c. 2200 m a.s.l., based on geomorphologic and paleoclimatic evidence. At present, the local TP-ELA is situated above the
mountain’s summit (c. 2918 m a.s.l.), but permanent snowfields and ice bodies survive within Megala Kazania cirque between c. 2400 and c. 2300 m a.s.l.,
because of the cirque’s maritime setting that results from its close proximity (c. 18 km) to the Aegean Sea and of the local topographical controls. The
snow and ice bodies occupied a considerably larger area and attained a stabilization phase between AD 1960 and 1980, also manifested from aerial
photographs, a period characterized by increased winter precipitation (Pw) with subsequent TP-ELA depression to c. 2410 m a.s.l. Mid- to late-20thcentury
Pw and TP-ELA variations exhibit negative correlations with the winter North Atlantic Oscillation index (NAOw) at annual and multidecadal
(30 years) timescales. Late Holocene (AD 1680–1860) reconstructed summer mean temperatures were lower by Ts < 1.1°C in relation to the reference
period between AD 1960 and 1980 and were also superimposed to negative NAOw phases, thus bracketing this time interval as a favorable one to glacial
formation and/or advance. Millennial-scale annual precipitation reconstructions at the hypothesized TP-ELA (c. 2200 m a.s.l.) point the period between
8 and 4 kyr BP as another glacier-friendly candidate. The mid-Holocene rather simplistic sequence of potential glacial advance phase was disturbed by
short-lived cold climatic deteriorations, well-documented over the northern Aegean region that may partly explain the multicrested shape of the highest
(c. 2200 m a.s.l.) morainic complex of Megala Kazania cirque.