Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics, 2015
In alpine environment, alluvial fan architecture can reveal important information about the lands... more In alpine environment, alluvial fan architecture can reveal important information about the landscape geomorphic evolution and the climate change. The information about alluvial fan morphology and sedimentology can be obtained by a high-resolution geophysical approach. In this work, we acquired and processed a ∼4 km long high-resolution seismic reflection profile across a representative transect of Val Venosta, over the Gadria fan, Eastern Alps, Italy, using non-conventional acquisition and processing approaches. We tested Dense-wide aperture arrays (DWA) and Common Reflection Surface stack (CRS) in a complex environment, in order to obtain seismic data with a quality and resolution adequate to: 1) study the internal reflective configuration of the fan; 2) image both the pattern of the bedrock below the valley and thickness of the sediment accumulation above it; 3) evaluate the geometrical relationships between the Gadria Fan and the Adige River sediments. By the analysis of our results, we can deduce that DWA seismic data in combination with high-resolution CDP/CRS processing can provide complimentary and low-cost information to aid the study of alluvial fans in alpine environments.
Studi di carattere meso-strutturale condotti nelle Dolomiti nord-orientali hanno permesso di rico... more Studi di carattere meso-strutturale condotti nelle Dolomiti nord-orientali hanno permesso di ricostruire la stratigrafia tettonica dell'area e, in particolare, di evidenziare la presenza di almeno quattro fasi deformative non coassiali fra loro e tutte di carattere compressivo. La cronologia relativa fra le diverse fasi, come ricavata direttamente in campagna utilizzando vari criteri di sovrapposizione fra strie e di antecedenza fra faglie, mostra una successione di eventi i cui assi di massima compressione hanno rispettivamente i seguenti orientamenti attuali: N58°E, N26°E, N346°E e N307°E (direzioni medie pesate). A causa dell'età delle rocce coinvolte (Permiano-Liassico), la cronologia assoluta è stata possibile soltanto per confronto con i risultati di simili ricerche condotte in altri settori della catena sudalpina. E' stato così possibile attribuire le seguenti età: tardo Cretaceo(?)-Paleogene (N58°E), Cattiano-Burdigaliano (N26°E), Serravalliano-Tortoniano (N346°E) e Messiniano superiore-Pliocene inferiore (N307°E). Le stesse ricerche hanno inoltre permesso di documentare l'evoluzione temporale dell'ellissoide degli sforzi la cui forma è variata da triassiale puramente compressionale (sigma3 subverticale), a triassiale trascorrente (sigma2 subverticale) attraverso uno stadio intermedio con geometria uniassiale (sigma2 = sigma3). Ulteriori indagini in questo settore delle Dolomiti, hanno poi messo in evidenza l'esistenza di un sistema regmatico, inaspettatamente complesso, che coinvolge l'area. Sono state riconosciute numerose strutture e, in base al comportamento cinematico prevalente, è stato possibile distinguere tre tipi principali: i) faglie trascorrenti, ii) faglie trastensive e iii) faglie contrazionali a basso e medio angolo. Il primo tipo è certamente quello maggiormente rappresentato e forma diversi set di piani paralleli che caratterizzano localmente interi settori della regione. Al contrario, le strutture trastensive sono sviluppate esclusivamente nel settore nordorientale e sono rappresentate da strutture a fiore negative, come la struttura della Croda dei Rondoi, e da graben, come quello di Croda dei Toni o delle Tre Cime di Lavaredo. Le faglie contrazionali a basso e medio angolo sono rappresentate da piani di taglio sia nord- che sud-vergenti, fra i quali il retroscorrimento di Dobbiaco, ma soprattutto l'Ansiei Thrust System, sono sicuramente le strutture più importanti. Quest'ultima, infatti, ha una estensione di oltre 30 km ed ha causato un raccorciamento di almeno 4-5 km. Tenendo conto sia della polifasicità della tettonica che del progressivo sollevamento e conseguente denudamento, viene infine tentata una ricostruzione dell'evoluzione generale di questo complesso sistema regmatico
The Calcari Grigi carbonate platform (Southern Alps, Italy) (size ~100km x 100km, up to 400m thic... more The Calcari Grigi carbonate platform (Southern Alps, Italy) (size ~100km x 100km, up to 400m thick) consists of several sub-environments (tidal flats, deep lagoons, oolitic shoals), now exhumed in the Southern Alps (Italy), a poorly deformed portion of the Mesozoic passive margin of Adria. Despite some alpine faulting and folding, lateral relationships between Jurassic units are still preserved. During Early Jurassic, the platform was affected by synsedimentary tectonics, testified by exposed structures, controlling sharp variations in the thickness of its units. Excellent outcrop continuity, extensive geological mapping and previousstudies provide a great wealth of field data that give the opportunity to produce a 3D model of a seismic-scale carbonate platform. 3D modeling was carried out with SKUA®. Main stratigraphic horizons and geometries of the sedimentary prisms were modeled. Spatial variability of the platform units’ thickness was studied with geostatistics to retrieve infor...
We reconstruct the post-Last Glacial Maximum (LGM) evolution of the upper Adige River floodplain,... more We reconstruct the post-Last Glacial Maximum (LGM) evolution of the upper Adige River floodplain, Eastern Italian Alps. In particular, we are interested in constraining the time scales associated with fan building and understanding how the relevant sediment supply at tributary confluences has interacted with the Adige River to form the present landscape configuration. By combining high-resolution seismic imaging with drillhole data and radiocarbon dating, we show (i) that similar to 80 % of the valley fill was deposited in post-LGM times, (ii) that sediment evacuation from tributaries began with local deglaciation at the end of the Younger Dryas; and (iii) that tributary basin aspect and size, by controlling the local pattern of deglaciation, may have delayed fan building by up to two millennia. Debris-flow sediment supply from the Gadria-Strimm system drove the evolution of this valley segment between 12 and 6.25 k.y. B.P., first deflecting, then damming the course of the Adige River, forming a lake, and affecting the shape and size of the neighboring fans. Our data show an anisotropic development of the Gadria fan, with growth focused on the central and eastern portion of the fan between 10 and 8.5 k.y. B.P., followed by gradual lateral shifting toward west for about the next two millennia. The estimated sediment yield associated with the fan formation describes a debris flow-driven paraglacial sedimentary wave that conforms to the conceptual model originally proposed by Church and Ryder (1972), but never tested before in upland basins with empirical data. The wave lasted for similar to 4 k.y. and around 9 k.y. B.P. peaked at similar to 390,000 m(3) yr(-1). At the valley profile scale, results suggest that similar fans functioned as effective sediment traps, which prevented, and still limit, fluvial reworking and valley floor incision. We argue that these geomorphic barriers, which have enhanced fragmentation of the valley long profile, with knickpoints located at major tributary fans, have delayed postglacial landscape recovery until today
This paper summarizes a project seminar in analytical chemistry that includes a method comparison... more This paper summarizes a project seminar in analytical chemistry that includes a method comparison approach and collaborative learning. In this project seminar, 12 students worked in four groups, ea...
Despite increased application of subsurface datasets below the limits of seismic resolution, reco... more Despite increased application of subsurface datasets below the limits of seismic resolution, reconstructing near‐surface deformation of shallow key stratigraphic markers beneath modern alluvial and coastal plains through sediment core analysis has received little attention. Highly resolved stratigraphy of Upper Pleistocene to Holocene (Marine Isotope Stage 5e to Marine Isotope Stage 1) alluvial, deltaic and coastal depositional systems across the southern Po Plain, down to 150 m depth, provides an unambiguous documentation on the deformation of previously flat‐lying strata that goes back in time beyond the limits of morphological, historical and palaeoseismic records. Five prominent key horizons, accurately selected on the basis of their sedimentological characteristics and typified for their fossil content, were used as highly effective stratigraphic markers (M1 to M5) that can be tracked for tens of kilometres across the basin. A facies‐controlled approach tied to a robust chronology (102 radiocarbon dates) reveals considerable deformation of laterally extensive nearshore (M1), continental (M2 and M3) and lagoon (M4 and M5) marker beds originally deposited in a horizontal position (M1, M4 and M5). The areas where antiformal geometries are best observed are remarkably coincident with the axes of buried ramp anticlines, across which new seismic images reveal substantially warped stratal geometries of Lower Pleistocene strata. The striking spatial coincidence of fold crests with the epicentres of historic and instrumental seismicity suggests that deformation of marker beds M1 to M5 might reflect, in part at least, syntectonically generated relief and, thus, active tectonism. Precise identification and lateral tracing of chronologically constrained stratigraphic markers in the 14C time window through combined sedimentological and palaeoecological data may delineate late Quaternary subsurface stratigraphic architecture at an unprecedented level of detail, outlining cryptic stratal geometries at the sub‐seismic scale. This approach is highly reproducible in tectonically active Quaternary depositional systems and can help to assess patterns of active deformation in the subsurface of modern alluvial and coastal plains worldwide.
Neogene indentation of the Adriatic plate into Europe led to major modifications of the Alpine or... more Neogene indentation of the Adriatic plate into Europe led to major modifications of the Alpine orogenic structures and style of deformation in the Eastern Alps. Especially, the offset of the Periadriatic Fault by the Northern Giudicarie Fault marks the initiation of strike-slip faulting and lateral extrusion of the Eastern Alps. Questions remain on the exact role of this fault zone in changes of the Alpine orogen at depth. This necessitates quantitative analysis of the shortening, kinematics and depth of decoupling underneath the Northern Giudicarie Fault and associated fold-and thrust belt in the Southern Alps. Tectonic balancing of a network of seven cross sections through the Giudicarie Belt parallel to the local shortening direction reveals that it comprises two kinematic domains with different amounts and partly overlapping ages of shortening. This data publication provides the cross sections that were not shown within Verwater et al. (2021, submitted to Solid Earth) (see figur...
Although the Cordillera de la Sal, close to San Pedro de Atacama (Chile), is one of the driest pl... more Although the Cordillera de la Sal, close to San Pedro de Atacama (Chile), is one of the driest places on Earth, it contains extensive cave systems that have developed in halite. A detailed morphological study of these caves, combined with 16 AMS radiocarbon ages on wood and bone fragments recovered from cave ceilings and diamictons, have allowed us to define when these systems formed and when sediments were emplaced. The sometimes huge cave passages appear to have formed in less than 2000 years by a succession of short-lived flash floods, probably after single extreme rain events.
Near Surface Geoscience 2015 - 21st European Meeting of Environmental and Engineering Geophysics, 2015
In alpine environment, alluvial fan architecture can reveal important information about the lands... more In alpine environment, alluvial fan architecture can reveal important information about the landscape geomorphic evolution and the climate change. The information about alluvial fan morphology and sedimentology can be obtained by a high-resolution geophysical approach. In this work, we acquired and processed a ∼4 km long high-resolution seismic reflection profile across a representative transect of Val Venosta, over the Gadria fan, Eastern Alps, Italy, using non-conventional acquisition and processing approaches. We tested Dense-wide aperture arrays (DWA) and Common Reflection Surface stack (CRS) in a complex environment, in order to obtain seismic data with a quality and resolution adequate to: 1) study the internal reflective configuration of the fan; 2) image both the pattern of the bedrock below the valley and thickness of the sediment accumulation above it; 3) evaluate the geometrical relationships between the Gadria Fan and the Adige River sediments. By the analysis of our results, we can deduce that DWA seismic data in combination with high-resolution CDP/CRS processing can provide complimentary and low-cost information to aid the study of alluvial fans in alpine environments.
Studi di carattere meso-strutturale condotti nelle Dolomiti nord-orientali hanno permesso di rico... more Studi di carattere meso-strutturale condotti nelle Dolomiti nord-orientali hanno permesso di ricostruire la stratigrafia tettonica dell'area e, in particolare, di evidenziare la presenza di almeno quattro fasi deformative non coassiali fra loro e tutte di carattere compressivo. La cronologia relativa fra le diverse fasi, come ricavata direttamente in campagna utilizzando vari criteri di sovrapposizione fra strie e di antecedenza fra faglie, mostra una successione di eventi i cui assi di massima compressione hanno rispettivamente i seguenti orientamenti attuali: N58°E, N26°E, N346°E e N307°E (direzioni medie pesate). A causa dell'età delle rocce coinvolte (Permiano-Liassico), la cronologia assoluta è stata possibile soltanto per confronto con i risultati di simili ricerche condotte in altri settori della catena sudalpina. E' stato così possibile attribuire le seguenti età: tardo Cretaceo(?)-Paleogene (N58°E), Cattiano-Burdigaliano (N26°E), Serravalliano-Tortoniano (N346°E) e Messiniano superiore-Pliocene inferiore (N307°E). Le stesse ricerche hanno inoltre permesso di documentare l'evoluzione temporale dell'ellissoide degli sforzi la cui forma è variata da triassiale puramente compressionale (sigma3 subverticale), a triassiale trascorrente (sigma2 subverticale) attraverso uno stadio intermedio con geometria uniassiale (sigma2 = sigma3). Ulteriori indagini in questo settore delle Dolomiti, hanno poi messo in evidenza l'esistenza di un sistema regmatico, inaspettatamente complesso, che coinvolge l'area. Sono state riconosciute numerose strutture e, in base al comportamento cinematico prevalente, è stato possibile distinguere tre tipi principali: i) faglie trascorrenti, ii) faglie trastensive e iii) faglie contrazionali a basso e medio angolo. Il primo tipo è certamente quello maggiormente rappresentato e forma diversi set di piani paralleli che caratterizzano localmente interi settori della regione. Al contrario, le strutture trastensive sono sviluppate esclusivamente nel settore nordorientale e sono rappresentate da strutture a fiore negative, come la struttura della Croda dei Rondoi, e da graben, come quello di Croda dei Toni o delle Tre Cime di Lavaredo. Le faglie contrazionali a basso e medio angolo sono rappresentate da piani di taglio sia nord- che sud-vergenti, fra i quali il retroscorrimento di Dobbiaco, ma soprattutto l'Ansiei Thrust System, sono sicuramente le strutture più importanti. Quest'ultima, infatti, ha una estensione di oltre 30 km ed ha causato un raccorciamento di almeno 4-5 km. Tenendo conto sia della polifasicità della tettonica che del progressivo sollevamento e conseguente denudamento, viene infine tentata una ricostruzione dell'evoluzione generale di questo complesso sistema regmatico
The Calcari Grigi carbonate platform (Southern Alps, Italy) (size ~100km x 100km, up to 400m thic... more The Calcari Grigi carbonate platform (Southern Alps, Italy) (size ~100km x 100km, up to 400m thick) consists of several sub-environments (tidal flats, deep lagoons, oolitic shoals), now exhumed in the Southern Alps (Italy), a poorly deformed portion of the Mesozoic passive margin of Adria. Despite some alpine faulting and folding, lateral relationships between Jurassic units are still preserved. During Early Jurassic, the platform was affected by synsedimentary tectonics, testified by exposed structures, controlling sharp variations in the thickness of its units. Excellent outcrop continuity, extensive geological mapping and previousstudies provide a great wealth of field data that give the opportunity to produce a 3D model of a seismic-scale carbonate platform. 3D modeling was carried out with SKUA®. Main stratigraphic horizons and geometries of the sedimentary prisms were modeled. Spatial variability of the platform units’ thickness was studied with geostatistics to retrieve infor...
We reconstruct the post-Last Glacial Maximum (LGM) evolution of the upper Adige River floodplain,... more We reconstruct the post-Last Glacial Maximum (LGM) evolution of the upper Adige River floodplain, Eastern Italian Alps. In particular, we are interested in constraining the time scales associated with fan building and understanding how the relevant sediment supply at tributary confluences has interacted with the Adige River to form the present landscape configuration. By combining high-resolution seismic imaging with drillhole data and radiocarbon dating, we show (i) that similar to 80 % of the valley fill was deposited in post-LGM times, (ii) that sediment evacuation from tributaries began with local deglaciation at the end of the Younger Dryas; and (iii) that tributary basin aspect and size, by controlling the local pattern of deglaciation, may have delayed fan building by up to two millennia. Debris-flow sediment supply from the Gadria-Strimm system drove the evolution of this valley segment between 12 and 6.25 k.y. B.P., first deflecting, then damming the course of the Adige River, forming a lake, and affecting the shape and size of the neighboring fans. Our data show an anisotropic development of the Gadria fan, with growth focused on the central and eastern portion of the fan between 10 and 8.5 k.y. B.P., followed by gradual lateral shifting toward west for about the next two millennia. The estimated sediment yield associated with the fan formation describes a debris flow-driven paraglacial sedimentary wave that conforms to the conceptual model originally proposed by Church and Ryder (1972), but never tested before in upland basins with empirical data. The wave lasted for similar to 4 k.y. and around 9 k.y. B.P. peaked at similar to 390,000 m(3) yr(-1). At the valley profile scale, results suggest that similar fans functioned as effective sediment traps, which prevented, and still limit, fluvial reworking and valley floor incision. We argue that these geomorphic barriers, which have enhanced fragmentation of the valley long profile, with knickpoints located at major tributary fans, have delayed postglacial landscape recovery until today
This paper summarizes a project seminar in analytical chemistry that includes a method comparison... more This paper summarizes a project seminar in analytical chemistry that includes a method comparison approach and collaborative learning. In this project seminar, 12 students worked in four groups, ea...
Despite increased application of subsurface datasets below the limits of seismic resolution, reco... more Despite increased application of subsurface datasets below the limits of seismic resolution, reconstructing near‐surface deformation of shallow key stratigraphic markers beneath modern alluvial and coastal plains through sediment core analysis has received little attention. Highly resolved stratigraphy of Upper Pleistocene to Holocene (Marine Isotope Stage 5e to Marine Isotope Stage 1) alluvial, deltaic and coastal depositional systems across the southern Po Plain, down to 150 m depth, provides an unambiguous documentation on the deformation of previously flat‐lying strata that goes back in time beyond the limits of morphological, historical and palaeoseismic records. Five prominent key horizons, accurately selected on the basis of their sedimentological characteristics and typified for their fossil content, were used as highly effective stratigraphic markers (M1 to M5) that can be tracked for tens of kilometres across the basin. A facies‐controlled approach tied to a robust chronology (102 radiocarbon dates) reveals considerable deformation of laterally extensive nearshore (M1), continental (M2 and M3) and lagoon (M4 and M5) marker beds originally deposited in a horizontal position (M1, M4 and M5). The areas where antiformal geometries are best observed are remarkably coincident with the axes of buried ramp anticlines, across which new seismic images reveal substantially warped stratal geometries of Lower Pleistocene strata. The striking spatial coincidence of fold crests with the epicentres of historic and instrumental seismicity suggests that deformation of marker beds M1 to M5 might reflect, in part at least, syntectonically generated relief and, thus, active tectonism. Precise identification and lateral tracing of chronologically constrained stratigraphic markers in the 14C time window through combined sedimentological and palaeoecological data may delineate late Quaternary subsurface stratigraphic architecture at an unprecedented level of detail, outlining cryptic stratal geometries at the sub‐seismic scale. This approach is highly reproducible in tectonically active Quaternary depositional systems and can help to assess patterns of active deformation in the subsurface of modern alluvial and coastal plains worldwide.
Neogene indentation of the Adriatic plate into Europe led to major modifications of the Alpine or... more Neogene indentation of the Adriatic plate into Europe led to major modifications of the Alpine orogenic structures and style of deformation in the Eastern Alps. Especially, the offset of the Periadriatic Fault by the Northern Giudicarie Fault marks the initiation of strike-slip faulting and lateral extrusion of the Eastern Alps. Questions remain on the exact role of this fault zone in changes of the Alpine orogen at depth. This necessitates quantitative analysis of the shortening, kinematics and depth of decoupling underneath the Northern Giudicarie Fault and associated fold-and thrust belt in the Southern Alps. Tectonic balancing of a network of seven cross sections through the Giudicarie Belt parallel to the local shortening direction reveals that it comprises two kinematic domains with different amounts and partly overlapping ages of shortening. This data publication provides the cross sections that were not shown within Verwater et al. (2021, submitted to Solid Earth) (see figur...
Although the Cordillera de la Sal, close to San Pedro de Atacama (Chile), is one of the driest pl... more Although the Cordillera de la Sal, close to San Pedro de Atacama (Chile), is one of the driest places on Earth, it contains extensive cave systems that have developed in halite. A detailed morphological study of these caves, combined with 16 AMS radiocarbon ages on wood and bone fragments recovered from cave ceilings and diamictons, have allowed us to define when these systems formed and when sediments were emplaced. The sometimes huge cave passages appear to have formed in less than 2000 years by a succession of short-lived flash floods, probably after single extreme rain events.
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