Marta Della Seta

Morphological and geochemical evidence of neotectonics in the volcanic area of Monti Vulsini (Latium, Italy)

Interdisciplinary research has been carried out to contribute to the definition of the neotectonic arrangement of the eastern area of Monti Vulsini, affected by Upper Pleistocene volcanic activity. Particularly, geochemical and geomorphological inquiries have been performed to identify tectonic elements whose recent activity could be related to the volcanic history of this area. The morphological field evidence of tectonics, as well as the analysis of azimuthal distribution of stream channels and the statistical analysis of the amplitude of relief (Ar), revealed the eastern Monti Vulsini volcanic area to be controlled by different tectonic alignments. At the same time the geochemical contribution, focused on geostatistical elaboration of soil–gas data, has attempted to process unbiased criteria to define soil–gas anomalies and to infer correlation with their fault-related linear geometry. In particular, rose diagrams of anomalous gas concentration alignments and azimuthal distribution of stream channels, performed for each hierarchical order, were compared to obtain information about the location and orientation of tectonic elements, as well as about the possible reconstruction of their activity in recent times, by means of relative chronology.

Spatio-temporal evolution of intraplate strike-slip faulting: The Neogene–Quaternary Kuh-e-Faghan Fault, central Iran

Central Iran provides an ideal region in which to study the long-term morphotectonic response to the nucleation and propagation of intraplate faulting. In this study, a multidisciplinary approach that integrates structural and stratigraphic field investigations with apatite (U + Th)/He (AHe) thermochronometry is used to reconstruct the spatio-temporal evolution of the Kuh-e-Faghan Fault in northeastern central Iran. The Kuh-e-Faghan Fault is a narrow, ~80-km-long, deformation zone that consists of three main broadly left-stepping, E-W–trending, dextral fault strands that cut through the Mesozoic–Paleozoic substratum and the Neogene–Quaternary sedimentary cover. The AHe thermochronometry results indicate that the intrafault blocks along the Kuh-e-Faghan Fault experienced two major episodes of fault-related exhumation at ca. 18 Ma and ca. 4 Ma. The ca. 18 Ma faulting/exhumation episode is chiefly recorded by the structure and depositional architecture of the Neogene deposits along the Kuh-e-Faghan Fault. A source-to-sink scenario can be reconstructed for this time frame, where topographic growth caused the synchronous erosion/exhumation of the pre-Neogene units and deposition of the eroded material in the surrounding fault-bounded continental depocenters. Successively, the Kuh-e-Faghan Fault gradually entered a period of relative tectonic quiescence and, probably, of regional subsidence, during which a thick pile of fine-grained onlapping sediments was deposited. This may have caused resetting of the He ages of apatite in the pre-Neogene and the basal Neogene successions. The ca. 4 Ma faulting episode caused the final exhumation of the fault system, resulting in the current fault zone and topography. The two fault-related exhumation episodes fit with regional early Miocene collision-enhanced uplift/exhumation, and the late Miocene–early Pliocene widespread tectonic reorganization of the Iranian Plateau. The reconstructed long-term, spatially and temporally punctuated fault system evolution in intraplate central Iran during Neogene–Quaternary times may reflect states of far-field stress changes at the collisional boundaries.

Geomorphic signal of active faulting at the northern edge of Lut Block: Insights on the kinematic scenario of Central Iran

Recent works documented Neogene to Quaternary dextral strike-slip tectonics along the Kuh-e-Sarhangi and Kuh-e-Faghan intraplate strike-slip faults at the northern edge of the Lut Block of Central Iran, previously thought to be dominated by sinistral strike-slip deformation. This work focuses on the evidence of Quaternary activity of one of these fault systems, in order to provide new spatiotemporal constraints on their role in the active regional kinematic scenario. Through geomorphological and structural investigation, integrated with optically stimulated luminescence dating of three generations of alluvial fans and fluvial terraces (at ~53, ~25, and ~6 ka), this study documents (i) the topographic inheritance of the long-term (Myr) punctuated history of fault nucleation, propagation, and exhumation along the northern edge of Lut Block; (ii) the tectonic control on drainage network evolution, pediment formation, fluvial terraces, and alluvial fan architecture; (iii) the minimum Holocene age of Quaternary dextral strike-slip faulting; and (iv) the evidence of Late Quaternary fault-related uplift localized along the different fault strands. The documented spatial and temporal constraints on the active dextral strike-slip tectonics at the northern edge of Lut Block provide new insights on the kinematic model for active faulting in Central Iran, which has been reinterpreted in an escape tectonic scenario.

Quantification and analysis of geomorphic processes on a recultivated iron ore mine on the Italian island of Elba using long-term ground-based lidar and photogrammetric SfM data by a UAV

This study focuses on the quantification and analysis of geomorphic processes on the barely vegetated slopes of a recultivated iron ore mine on the Italian island of Elba using photographs from terrestrial laser scanning (TLS) and digital photogrammetry by an unmanned aerial vehicle (UAV) over a period of 5 1/2 years. Beside this, the study tried to work out the potential and the limitations of both methods to detect surface changes by geomorphic process dynamics within a natural environment. Both UAV and TLS show the pattern of the erosion and accumulation processes on the investigated slope quite well, but the calculated amounts differ clearly between the methods. The reasons for these differences could be found in the different accuracies (variable level of detections) of the methods and the different viewing geometries. Both effects have an impact on the detectable process dynamics over different timescales on the slope and their calculated amounts, which in both cases can lead to an underestimation of erosion and accumulation by fluvial processes.

Stream Length-Gradient Index Mapping as a Tool for Landslides Identification

The Stream Length-Gradient (SL) index is used to detect knickpoints potentially related to surface and sub-surface deformation processes. In this work, the SL index has been calculated along streams draining the southern sector of the Emilia-Romagna Region within the Northern Apennines (Italy), to detect knickpoints associated with active landslides. The methodology allowed the rapid analysis of an area of ca. 2300 km\(^{2}\). Approximately thirty hillslopes potentially affected by landslides were identified studying the SL index outlier values. Field survey confirmed the presence of large deep-seated landslides associated with 90 % of the observed anomalies. This study illustrates that stream profiles metrics may have a high potential in different geological studies covering wide areas in a short time and investing limited resources.

Relief, Intermontane Basins and Civilization in the Umbria-Marche Apennines: Origin and Life by Geological Consent

The landscape of the Umbria-Marche Apennines (Central Italy) shows a rhythmic sequence of “whaleback” anticlinal ridges separated by longitudinal synformal valleys. In this topographic arrangement, flat-floored tectonic depressions appear which enclose a wide range of landforms, and witness the continuous balance between tectonic forces, Quaternary climatic phases and drainage network adjustment. Fault scarps and triangular facets characterize the bordering slopes where thick talus deposits and landslides highlight the gravitational component. Karstic landforms as dolines and caves and fluvial features testify to the action of water. The resulting landscape is, for a visitor, like an incomparable geological handbook.

High-resolution geological model of the gravitational deformation affecting the western slope of Mt. Epomeo (Ischia)

The recent geological history of Ischia Island is characterized by slope-scale gravitational deformations closely related to volcano-tectonic dynamics of the Mt. Epomeo resurgent caldera. This study focuses on the gravitational deformation that involves alkali-trachytic lava and trachytic ignimbrite flow-units of Mt. Nuovo, located in the western portion of Mt. Epomeo. A preliminary, high-resolution engineering-geological model was obtained through geological, geomorphological and geophysical surveys and reveals a complex morpho-structure with geomorphological evidence of gravitational instability. The complexity of the ongoing slope deformations is confirmed by field geo-structural evidences that led to the identification of a multiple compound mechanism with a main rupture surface which is about 200 m deep. This geometry was better constrained by passive seismic investigations consisting in noise measurements, focused on resonance frequencies of the soil (i.e. based on H/V Nakamura approach). In addition, a close relationship between the outcrop of Mt. Epomeo Green Tuff breccia layers and the distribution of hydrothermal emissions and gas vent can be inferred, as it is related to the higher permeability of the breccia layers with respect to the main Mt. Epomeo Green Tuff flow unit, where the ascent path of deep hydrothermal fluids developed along faults and fracture networks.

Testing geomorphic signal of active normal faulting: The case of the Cittanova Fault (Calabria, southern Italy): Testing geomorphic signal of active normal faulting (Cittanova Fault)

Extracting tectonic signals from the landscape is an important challenge for constraining the style and rate of deformation associated with active faults, especially where their displacement history cannot be independently determined. Based on previous paleoseismological data coupled with new geomorphological field work and C dating of geomorphic markers, we analysed the geomorphic signal of the along-strike differential throw of the Cittanova Fault in southern Calabria (Italy), the recent activity of which is already well documented and constrained. Through DTM-derived stream power law parameters (SL and χ), we provide evidence of drainage network disequilibrium and reorganization in response to fault growth and deformation style. Furthermore, a methodological test of the reliability of the χmetric as a proxy for the differential throw along the strike of active normal faults provided good preliminary results, consistent with a strong inverse linear correlation with fault throw. Copyright

The Role of Lithology

Abstract Badlands can develop on bedrock and/or weathered material, the characteristics of which play a key role on hillslope processes in a range of climate conditions. Therefore, fundamental attention should be given to badland materials, the main features of which are grain size, clay mineralogy and physico-chemical characteristics. The typical weathering profile consists of crust, subsurface and unweathered material, but depending on climatic, lithological, topographic and hydrological factors, the properties and appearance of both surface and subsurface materials change over time. Through time, regolith formed on erodible and dispersive bedrock materials tends to stabilize, again as a function of slope and climate conditions because prolonged precipitation can cause decrease in surface strength and runoff and reduce the dispersivity of the surface. Vegetation also has distinct role in stabilizing the clayey sediments due to lowering the dispersivity in the upper horizon of the badland material, even though such stabilization is often not permanent and erosion processes can sometimes reoccur. Finally, all the above cited factors and properties of badland materials play a complex and key role in the development of different geomorphic processes and related landforms.

The use of the slope-area function to analyse process domains in complex badland landscapes: Process domains in complex badland landscape

This paper explores the effectiveness of the widely-used functional relationship between drainage area (A in m) and slope (S in m/m) to identify local process domains and aid interpretation of process interactions in a complex badland landscape. In order to perform this investigation, a series of sub-basins tributary to the Formone River in the Orcia catchment (central Italy) were selected as a suitable study area within which to explore our questions, given these basins’ general representativeness of local terrain, the availability of a high resolution digital terrain model and previous extensive geomorphological research. Eroding basins containing both calanchi and landslides are common in the sub-humid badland landscape of central Italy, where field observation identifies a complex pattern of erosive processes associated with a history of uplift, despite which parts of the local landscape appear disconnected. Results reveal that the shape of all S–A curves (plotted using S data binned on log A) is comparable with that described in the literature, although sub-basins containing calanchi generally plot with higher S values than non-calanchi ones, except in the ‘fluvial’ section of the plots. Second, when viewed on total data (non-binned) S–A plots, landslide source area domains and calanchi domains are entirely coincident in all basins, supporting a cause–effect relationship. Additional plotting of the frequency characteristics of the raw data in a new way supports the interpretation that calanchi frequently initiate in landslide scars. In general though, although the S–A plots can contribute to the disentanglement of geomorphological behaviour in some complex erosional landscapes, it became apparent that in this landscape, process domains do not separate out with clarity along the A axis as suggested by theory. Despite this, an alternative, broader-scale morphoevolutive model can be proposed for the development of within-landslide calanchi, driven by changes to basin connectivity to the base channel.