Clara Mangili - Academia.edu (original) (raw)

Papers by Clara Mangili

In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurr... more In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurred over a period of 9.3 kyr in the Piànico-Sèllere Basin (southern Alps) during an interglacial period in the Pleistocene (sometime from 780 to 393 ka) and analyse its correlation, clustering, and cyclicity properties. We first examine correlations, by applying power-spectral analysis and detrended fluctuation analysis (DFA) to a time series of the number of floods per decade, and find weak long-range persistence: a power-spectral exponent beta-PS approx. 0.39 and an equivalent power-spectral exponent from DFA, beta-DFA approx. 0.25. We then examine clustering using the one-point probability distribution of the inter-flood intervals and find that the palaeofloods cluster in time as they are Weibull distributed with a shape parameter kW = 0.78. We then examine cyclicity in the time series of number of palaeofloods per year, and find a period of about 2030 years. Using these characterizations of the correlation, clustering, and cyclicity in the original palaeoflood time series, we create a model consisting of the superposition of a fractional Gaussian noise (FGN) with a 2030-year periodic component and then peaks over threshold (POT) applied. We use this POTFGN+Period model to create 2 600 000 synthetic realizations of the same length as our original palaeoflood time series, but with varying intensity of periodicity and persistence, and find optimized model parameters that are congruent with our original palaeoflood series. We create long realizations of our optimized palaeoflood model, and find a high temporal variability of the flood frequency, which can take values of between 0 and > 30 floods century-1. Finally, we show the practical utility of our optimized model realizations to calculate the uncertainty of the forecasted number of floods per century with the number of floods in the preceding century. A key finding of our paper is that neither fractional noise behaviour nor cyclicity is sufficient to model frequ [...]

EGUGA, Apr 1, 2015

One of the most interesting morphological feature on the surface of Mars are paleolakes: time cap... more One of the most interesting morphological feature on the surface of Mars are paleolakes: time capsules and low-energy depositional settings that preserve hints on the ancient environment and, possibly, traces of life. On Earth, lakes host a huge diversity of habitats where life is flourishing; hence, on Mars, they may have once supported life too. In order to understand the paleohydrology of these basins, the estimation of the water discharge flowing into their tributary and/or outlets can give important clues on the water cycle on the planet. On Mars, the most common modeling used to reconstruct the hydraulic properties are based on the adaptation of terrestrial empirical relationship, less focusing on more sophisticated hydraulic models. The main objective of this study is to separately analyze the hydraulic characteristics of the tributary and the outlet of a paleolake located in the Menmonia quadrangle by using an hydraulic model based on the energy and momentum equations of the body of water enclosed in the channels. The lengths of the analyzed river reaches are ∼ 10 km and ∼ 19 km, the outlet and the tributary respectively. A Monte Carlo procedure coupled to geomorphological evidences of the paleowater surface (e.g. terraces levels) were used to constrain the hydraulic parameters of the system. The Mars Express High-resolution stereo camera digital elevation model, H31850000DA4 with a spatial resolution on 75 m, is hence used to characterize the geometry of the study area. In this contribution we provide estimates on the magnitude of the bankfull discharge and roughness coefficient of the tributary and the outlet of the paleolake; moreover, on the basis of these results, the probable water depth of the lake is inferred. Finally, a discussion on the possibility that the system inlet-lake-outlet was acting simultaneously is also presented. Consequently, a sensitivity analysis is performed to examine the accuracy of the results to the main sources of uncertainty concerning the methodology, as well as, the uncertainty in the geomorphological evidences used to constrain the hydraulic modelling. Given the comparable discharge estimates of the tributary and the outlet, as well as the coherent elevation and width of their mouths into the lake, the results suggest that both channels were most probably acting simultaneously during their last evolutionary phase, with a discharge equal to ∼ 6000 m 3 s −1 and a water surface elevation in the lake equal to ∼-1400 m. This contribution supports the hypothesis of an ancient and articulated hydrologic system acting in the study area.

In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurr... more In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurred over a period of 9.3 kyr in the Piànico-Sèllere Basin (southern Alps) during an interglacial period in the Pleistocene (sometime from 780 to 393 ka) and analyse its correlation, clustering, and cyclicity properties. We first examine correlations, by applying power-spectral analysis and detrended fluctuation analysis (DFA) to a time series of the number of floods per decade, and find weak long-range persistence: a power-spectral exponent beta-PS approx. 0.39 and an equivalent power-spectral exponent from DFA, beta-DFA approx. 0.25. We then examine clustering using the one-point probability distribution of the inter-flood intervals and find that the palaeofloods cluster in time as they are Weibull distributed with a shape parameter kW = 0.78. We then examine cyclicity in the time series of number of palaeofloods per year, and find a period of about 2030 years. Using these characterizati...

This work presents an example of lacustrine and fluvial terraces correlation, a useful approach f... more This work presents an example of lacustrine and fluvial terraces correlation, a useful approach for the understanding and reconstruct past changes in landscape evolution not only on Earth but also on Mars

Quaternary Science Reviews, 2007

The palaeolake record from Piànico (Southern Alps) comprises a sequence of 15,500 continuous calc... more The palaeolake record from Piànico (Southern Alps) comprises a sequence of 15,500 continuous calcite varves formed during peak interglacial conditions around 400 ka ago. The varved nature of these deposits allows precise sub-sampling of five varve year intervals for stable isotope analyses. All samples consist of calcite precipitated in the epilimnion of the lake, with contents of detrital carbonate below 4%. Four significant negative δ 18 O oscillations occurred during the upper half of the interglacial. The most prominent of these oscillations has an amplitude of-1.1% and lasted 780 varve years. The three other oscillations are shorter (125-195 varve years) and of lower amplitude (0.4-0.9‰). An additional major drop in δ 18 O occurs 315 varve years before the end of continuous calcite precipitation in the lake. This shift marks the end of long interglacial conditions and the beginning of harsher climate conditions and glacier advances in the Southern Alps. In contrast, the four δ 18 O oscillations within the period of continuous formation of calcite varves reflect natural intra-interglacial climate dynamics.

Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomo... more Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomorphic features. The ancient major Martian water fluxes vanished about 3.5 Ga. Meteoritic impacts, wind-erosion, gravity-related phenomena, tectonic deformations and volcanic activities deeply altered the landforms during the ages. Hence, the reconstruction of water-shaped landscapes is often complicated. Fluvial and lacustrine terraces analysis and correlation is a useful approach to understand and reconstruct the past changes in Martian landscape evolution. These features are commonly used as reference for the top of water bodies on Earth, since they are void of the uncertainties or errors deriving from erosional or slumping processes that could have acted on the valley flanks or in the plateau, where the hydrological network was carved in. The study area is located in the western hemisphere of Mars, in the Memnonia quadrangle, between latitude 9˚10'-9˚50'South and longitude 167˚0'-167˚30' West and it constitutes a transition region between the southern highlands of Terra Sirenum and the northern lowlands of Lucus Planum. Many water-shaped features have already been described near the study area, the most prominent of them being the Ma'adim Vallis and the Mangala Valles system. Our results derive from the observations and the analysis of HRSC images (12.5 m spatial resolution) and Digital Elevation Models (DEMs) derived from the MEX-HRSC (75 m resolution), that allow the identification of elevation differences up to the tens of meter scale. We were able to reconstruct six main evolutionary stages of a complex hydrologic systems consisting of two main palaeorivers (up to 5 km wide) connected one another by a palaeolake that formed within a meteor crater (∼20 km diameter). On the basis of Earth analogs, these stages/terraces should have evolved during a long period of time, at least thousands years long. Furthermore, crater counting date back the deactivation of the system to ca 3.5±0.1 Ga ago, suggesting the presence of a stable environment with subaerial water fluxes during the Late Hesperian, very close to the liquid-water disappearance. Apart from the above mentioned reasons, the increasing interest and ongoing programs of on-site Martian exploration are additional reasons to study fluviolacustrine depositional environments. Together with the technology improvements that lead to more flexible safety constraints for landing/exploring, the possibility to focus on specific and more detailed scientific aspects is enhanced.

ROVER. M. Pajola 1 , J. Carter 2 , S. Rossato 3 , E. Baratti 4 , C. Mangili 5 , K. S. McBride 6 a... more ROVER. M. Pajola 1 , J. Carter 2 , S. Rossato 3 , E. Baratti 4 , C. Mangili 5 , K. S. McBride 6 and M. Coradini 7,8 , 1 CISAS “G. Colombo”, University of Padova, 15 Via Venezia, 35131 Padova, Italy (maurizio.pajola@studenti.unipd.it; maurizio.pajola@gmail.com), 2 IAS, Paris-Sud University, France, 3 Geosciences Dept., University of Padova, Italy, 4 DICAM Dept., University of Bologna, Italy, 5 EES, University of Geneva, Switzerland, 6 IGPP-UCLA, USA, 7 ESA, France, 8 JPL-CALTECH, USA.

Reviews of Geophysics, 2015

In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurr... more In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurred over a period of 9.3 kyr in the Piànico-Sèllere Basin (southern Alps) during an interglacial period in the Pleistocene (sometime from 780 to 393 ka) and analyse its correlation, clustering, and cyclicity properties. We first examine correlations, by applying power-spectral analysis and detrended fluctuation analysis (DFA) to a time series of the number of floods per decade, and find weak long-range persistence: a power-spectral exponent beta-PS approx. 0.39 and an equivalent power-spectral exponent from DFA, beta-DFA approx. 0.25. We then examine clustering using the one-point probability distribution of the inter-flood intervals and find that the palaeofloods cluster in time as they are Weibull distributed with a shape parameter kW = 0.78. We then examine cyclicity in the time series of number of palaeofloods per year, and find a period of about 2030 years. Using these characterizations of the correlation, clustering, and cyclicity in the original palaeoflood time series, we create a model consisting of the superposition of a fractional Gaussian noise (FGN) with a 2030-year periodic component and then peaks over threshold (POT) applied. We use this POTFGN+Period model to create 2 600 000 synthetic realizations of the same length as our original palaeoflood time series, but with varying intensity of periodicity and persistence, and find optimized model parameters that are congruent with our original palaeoflood series. We create long realizations of our optimized palaeoflood model, and find a high temporal variability of the flood frequency, which can take values of between 0 and > 30 floods century-1. Finally, we show the practical utility of our optimized model realizations to calculate the uncertainty of the forecasted number of floods per century with the number of floods in the preceding century. A key finding of our paper is that neither fractional noise behaviour nor cyclicity is sufficient to model frequ [...]

EGUGA, Apr 1, 2015

One of the most interesting morphological feature on the surface of Mars are paleolakes: time cap... more One of the most interesting morphological feature on the surface of Mars are paleolakes: time capsules and low-energy depositional settings that preserve hints on the ancient environment and, possibly, traces of life. On Earth, lakes host a huge diversity of habitats where life is flourishing; hence, on Mars, they may have once supported life too. In order to understand the paleohydrology of these basins, the estimation of the water discharge flowing into their tributary and/or outlets can give important clues on the water cycle on the planet. On Mars, the most common modeling used to reconstruct the hydraulic properties are based on the adaptation of terrestrial empirical relationship, less focusing on more sophisticated hydraulic models. The main objective of this study is to separately analyze the hydraulic characteristics of the tributary and the outlet of a paleolake located in the Menmonia quadrangle by using an hydraulic model based on the energy and momentum equations of the body of water enclosed in the channels. The lengths of the analyzed river reaches are ∼ 10 km and ∼ 19 km, the outlet and the tributary respectively. A Monte Carlo procedure coupled to geomorphological evidences of the paleowater surface (e.g. terraces levels) were used to constrain the hydraulic parameters of the system. The Mars Express High-resolution stereo camera digital elevation model, H31850000DA4 with a spatial resolution on 75 m, is hence used to characterize the geometry of the study area. In this contribution we provide estimates on the magnitude of the bankfull discharge and roughness coefficient of the tributary and the outlet of the paleolake; moreover, on the basis of these results, the probable water depth of the lake is inferred. Finally, a discussion on the possibility that the system inlet-lake-outlet was acting simultaneously is also presented. Consequently, a sensitivity analysis is performed to examine the accuracy of the results to the main sources of uncertainty concerning the methodology, as well as, the uncertainty in the geomorphological evidences used to constrain the hydraulic modelling. Given the comparable discharge estimates of the tributary and the outlet, as well as the coherent elevation and width of their mouths into the lake, the results suggest that both channels were most probably acting simultaneously during their last evolutionary phase, with a discharge equal to ∼ 6000 m 3 s −1 and a water surface elevation in the lake equal to ∼-1400 m. This contribution supports the hypothesis of an ancient and articulated hydrologic system acting in the study area.

In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurr... more In this paper, we present a unique 9.5 m palaeolacustrine record of 771 palaeofloods which occurred over a period of 9.3 kyr in the Piànico-Sèllere Basin (southern Alps) during an interglacial period in the Pleistocene (sometime from 780 to 393 ka) and analyse its correlation, clustering, and cyclicity properties. We first examine correlations, by applying power-spectral analysis and detrended fluctuation analysis (DFA) to a time series of the number of floods per decade, and find weak long-range persistence: a power-spectral exponent beta-PS approx. 0.39 and an equivalent power-spectral exponent from DFA, beta-DFA approx. 0.25. We then examine clustering using the one-point probability distribution of the inter-flood intervals and find that the palaeofloods cluster in time as they are Weibull distributed with a shape parameter kW = 0.78. We then examine cyclicity in the time series of number of palaeofloods per year, and find a period of about 2030 years. Using these characterizati...

This work presents an example of lacustrine and fluvial terraces correlation, a useful approach f... more This work presents an example of lacustrine and fluvial terraces correlation, a useful approach for the understanding and reconstruct past changes in landscape evolution not only on Earth but also on Mars

Quaternary Science Reviews, 2007

The palaeolake record from Piànico (Southern Alps) comprises a sequence of 15,500 continuous calc... more The palaeolake record from Piànico (Southern Alps) comprises a sequence of 15,500 continuous calcite varves formed during peak interglacial conditions around 400 ka ago. The varved nature of these deposits allows precise sub-sampling of five varve year intervals for stable isotope analyses. All samples consist of calcite precipitated in the epilimnion of the lake, with contents of detrital carbonate below 4%. Four significant negative δ 18 O oscillations occurred during the upper half of the interglacial. The most prominent of these oscillations has an amplitude of-1.1% and lasted 780 varve years. The three other oscillations are shorter (125-195 varve years) and of lower amplitude (0.4-0.9‰). An additional major drop in δ 18 O occurs 315 varve years before the end of continuous calcite precipitation in the lake. This shift marks the end of long interglacial conditions and the beginning of harsher climate conditions and glacier advances in the Southern Alps. In contrast, the four δ 18 O oscillations within the period of continuous formation of calcite varves reflect natural intra-interglacial climate dynamics.

Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomo... more Liquid water was flowing on the surface of Mars in the past, leaving behind a wide range of geomorphic features. The ancient major Martian water fluxes vanished about 3.5 Ga. Meteoritic impacts, wind-erosion, gravity-related phenomena, tectonic deformations and volcanic activities deeply altered the landforms during the ages. Hence, the reconstruction of water-shaped landscapes is often complicated. Fluvial and lacustrine terraces analysis and correlation is a useful approach to understand and reconstruct the past changes in Martian landscape evolution. These features are commonly used as reference for the top of water bodies on Earth, since they are void of the uncertainties or errors deriving from erosional or slumping processes that could have acted on the valley flanks or in the plateau, where the hydrological network was carved in. The study area is located in the western hemisphere of Mars, in the Memnonia quadrangle, between latitude 9˚10'-9˚50'South and longitude 167˚0'-167˚30' West and it constitutes a transition region between the southern highlands of Terra Sirenum and the northern lowlands of Lucus Planum. Many water-shaped features have already been described near the study area, the most prominent of them being the Ma'adim Vallis and the Mangala Valles system. Our results derive from the observations and the analysis of HRSC images (12.5 m spatial resolution) and Digital Elevation Models (DEMs) derived from the MEX-HRSC (75 m resolution), that allow the identification of elevation differences up to the tens of meter scale. We were able to reconstruct six main evolutionary stages of a complex hydrologic systems consisting of two main palaeorivers (up to 5 km wide) connected one another by a palaeolake that formed within a meteor crater (∼20 km diameter). On the basis of Earth analogs, these stages/terraces should have evolved during a long period of time, at least thousands years long. Furthermore, crater counting date back the deactivation of the system to ca 3.5±0.1 Ga ago, suggesting the presence of a stable environment with subaerial water fluxes during the Late Hesperian, very close to the liquid-water disappearance. Apart from the above mentioned reasons, the increasing interest and ongoing programs of on-site Martian exploration are additional reasons to study fluviolacustrine depositional environments. Together with the technology improvements that lead to more flexible safety constraints for landing/exploring, the possibility to focus on specific and more detailed scientific aspects is enhanced.

ROVER. M. Pajola 1 , J. Carter 2 , S. Rossato 3 , E. Baratti 4 , C. Mangili 5 , K. S. McBride 6 a... more ROVER. M. Pajola 1 , J. Carter 2 , S. Rossato 3 , E. Baratti 4 , C. Mangili 5 , K. S. McBride 6 and M. Coradini 7,8 , 1 CISAS “G. Colombo”, University of Padova, 15 Via Venezia, 35131 Padova, Italy (maurizio.pajola@studenti.unipd.it; maurizio.pajola@gmail.com), 2 IAS, Paris-Sud University, France, 3 Geosciences Dept., University of Padova, Italy, 4 DICAM Dept., University of Bologna, Italy, 5 EES, University of Geneva, Switzerland, 6 IGPP-UCLA, USA, 7 ESA, France, 8 JPL-CALTECH, USA.

Reviews of Geophysics, 2015