Tectonic and sedimentary evolution of the Gulf of Aden continental margins: new structural and stratigraphic data

The purpose of this work is to reconstruct the tectonic and stratigraphic evolution of the eastern sectors of these young margins. New structural and stratigraphic data were collected for the two continental margins facing the Gulf of Aden, in northern Somalia and southern Yemen, by integrating field work, aerial photo analysis and satellite multispectral data processing. A detailed stratigraphic correlation of pre-rift, Mesozoic to Eocene strata was constructed through north-eastern Somalia (Migiurtinia region), and selected sections were correlated between the two sides of the Gulf. The analysis of the deformation of these strata leads to the recognition of west-north-west-east-south-east trending half-graben and tectonic depressions, separated by structural highs interpreted as transfer zones. The transfer zones appear to be located on the landward extension of transform faults in the oceanic setting of the Gulf, and the tectonic depressions are approximately parallel to the oceanic ridge. Oligo-Miocene syn-tectonic basins developed within the depressions, and their patterns reflect their tectonic evolution of the eastern sector of the Gulf of Aden. The age of the deposits sealing the faults cutting Eocene strata confirm a early-middle Oligocene age for the beginning of rifting. The restoration of the pre-drift setting leads to a matching of the continental structures, such as basins and transfer zones, on the two sides of the Gulf. The comparison between the tectonic and stratigraphic features of both continental margins and the oceanic setting of the Gulf of Aden, indicates that a progressive crustal extension brought about the formation of oceanic spreading centres which correspond to the pre-existing syn-rift basins

Old recipes, new strategies: Paleoenvironment, georesources, building materials, and trade networks in Roman Tuscany (Italy)

© 2020 Wiley Periodicals, Inc. The Grosseto plain has undergone extensive morphological changes. The shoreline progression has been taking place during the last millennium and has deeply affected settlement, infrastructural, and socioeconomic dynamics. Consequently, this study aims to (a) localize the raw materials exploited during the Roman period for building materials production, (b) reconstruct the production technology, and (c) provide a meaningful reconstruction of the commercial dynamics between local “municipal” productions and “urban” imports. The chemical, mineralogical, and petrographic investigations performed on 34 stamped bricks from the Roman territories of Vetulonia, Rusellae, Heba (Aia Nova), and Saturnia supported the following major achievements: (a) Most of the Rusellan producers used the continental deposits outcropping along the Ombrone River while a few of them exploited the coastal or marine deposits. Aia Nova and Saturnia producers used the Zanclean marine deposits. (b) Brick-making technology involved very little or no preparation of the paste and firing temperatures ranging between ~650°C and 900°C. Calcite temper was found in Rusellan bricks while decantation was hypothesized for Saturnia bricks only. (c) Commercial dynamics changed abruptly after the the mid 1st century AD when local productions, run by local aristocracies, started declining in favor of urban imports, until being completely supplanted during the Trajan age

Integrazione tra tecniche di Fotogrammetria Digitale Terrestre e Laser Scanning per la caratterizzazione dei volumi di roccia instabili

Aim of the study is the analysis of brittle structures for the exploitation and the evaluation of rock slopes stability by deterministic approach. This is achieved through both photogrammetric and laser scanning techniques in order to obtain a detailed geometrical survey of jointing systems, slopes and potential blocks and wedges. Based on these techniques, detailed digital elevation models and orthophotos can be created and then they can be used as data source for studying the rocky slope stability. Considering the inaccessibility of most part of the rocky slopes, the photogrammetric equipment has been mounted on an aerostatic balloon or an helicopter. The laser scanned the surfaces from the ground thanks to its wide range working methods

Rock slope stability and runout analysis for geological risk mapping in the Marina Piccola bay (Capri Island, Italy)

Thanks to modern geotechnologies, recent studies reveal that many urbanized areas are sited by rock fall hazard of high degree. Due to their particular location, buildings and houses in such areas are often exposed to high risk caused by the overhead presence of potentially unstable blocks. In this paper, the case study of “Grotta delle Felci” cliff (Solaro Mountain, Naples – Italy) is presented. With the aim of updating the existing geological risk map of the Marina Piccola bay, a study of the rock slope stability was performed using traditional geological surveys, Digital Terrestrial Photogrammetry (DTP), Laser Scanning (LS) and topo-graphic GPS and Total Station measurements. The use of DTP is recommended especially in inaccessible sites such as, quarries, mountain slopes and natural cliffs. From LS points cloud and oriented stereo-images, re-spectively the Digital Dense Surface Model (DDSM) and the cliff orthophoto were produced. The analysis of DDSM and stereopairs allowed to derive fundamental data for studying the slope stability such as the geometrical characteristics of joints (position, attitude, spacing and persistence), the blocks shape and volume and the local morphology dip and dip direction. Then, a runout analysis of unstable blocks and wedges was performed with the goal of highlighting the most dangerous areas at the bottom of the cliff and of defining the kinetic energy of possible blocks along their falling paths. Following a deterministic approach, the geometrical information, combined with data from traditional engineering-geological survey, was used to study the slope stability both by the limit equilibrium conventional method and distinct elements numerical analysis. Final results about cliff stability and runout analysis, combined with the vulnerability of buildings and roads, allowed to propose the updated geological risk map and to advise the most suitable protection works to mitigate the hazard