The Neogene–Quaternary Albegna basin (southern Tuscany, central Italy), located to the south of the active geothermal field of Monte Amiata, hosts fossil and active thermogene travertine deposits, which are used in this study to... more
The Neogene–Quaternary Albegna basin (southern Tuscany, central Italy), located to the south of the active geothermal field of Monte Amiata, hosts fossil and active thermogene travertine deposits, which are used in this study to reconstruct the spatio-temporal evolution of the feeding hydrothermal system. Travertine deposition is controlled by regional tectonics that operated through distributed N-S– and approximately E-W–striking transtensional fault arrays. The geochronological data set (230Th/234U, uranium-series disequilibrium) indicates a general rejuvenation (from >350 to <40 ka) of the travertine deposits moving from north to south and from higher to lower elevations. Negative d13C and positive d18O trends with younger deposition ages and lower depositional elevations provide evidence for a change in space and time of the hydrothermal fluid supply, suggesting a progressive dilution of the endogenic fluid sources by increasing meteoric water inputs. Comparison with paleoclimate records suggests increased travertine deposition during humid interglacial periods characterized by highstands of the water table. Travertine deposits of the Albegna basin record the interactions and feedbacks among tectonics, hydrothermalism, and paleoclimate within a region of positive geothermal anomaly during the Quaternary. Our study also sheds light on the neotectonic evolution of the Tyrrhenian margin of central Italy, where hydrothermalism has been distributed along margin-transverse structures during the Pleistocene and Holocene. It is hypothesized that originally upper-crustal, margin-transverse faults have evolved to through-going crustal features during the Quaternary, providing structurally controlled pathways for hydrothermal fluids. We suggest that this was the consequence of a change in the relative magnitude of the principal stress vectors along the Tyrrhenian margin that occurred under a regional stress field dominated by a continuous extensional regime.
In the present study landscape information viz. lineament, drainage, altimetric and hypsometric analysis has been worked out. The study area is a coastal tract which lies between Jaigarh Creek in the North to Pavas Creek in the South from... more
In the present study landscape information viz. lineament, drainage, altimetric and hypsometric analysis has been worked out. The study area is a coastal tract which lies between Jaigarh Creek in the North to Pavas Creek in the South from Maharashtra State, India. The area covered during present investigation is drained by the streams which originate in the Sahyadri ranges of the Western Ghats and follow short tumultuous courses. Majority of streams follow East - West course, some follow NW - SE and NE - SW courses. Most of the streams are characterised by straight segments with acute angle turns, indicative of structural control. This structural control has given rise to drainage anomalies. Most of the streams in their upper reaches exhibit the presence of rapids, which occur, generally at elevations of 60 - 70m amsl. Their height ranges from 1m to 15m. From topographic sheets and LANDSAT - I imageries inferred that the majority of the streams have been controlled by lineaments. Satellite imagery reveals that major streams like Kajavi have been controlled by NW - SE lineament, while river Shastri has been controlled by NE - SW lineament. From the hypsometric values it is inferred that the higher order streams show Monadnock phase, whereas, the hypsometric values indicate maturity stage. It can be said that the area under investigation indicates Monadnock phase of aeration which represents the residual hills.
En los años 60 del pasado siglo, las metrópolis de occidente han sufrido ya importantes mutaciones en un proceso de desarrollo lanzado después de la Segunda Guerra Mundial, que ya apunta los rasgos de la ciudad contemporánea. La nueva... more
En los años 60 del pasado siglo, las metrópolis de occidente han sufrido ya importantes mutaciones en un proceso de desarrollo lanzado después de la Segunda Guerra Mundial, que ya apunta los rasgos de la ciudad contemporánea. La nueva realidad urbana, frente a la compacidad de la ciudad histórica, contiene nuevas áreas, nuevos tejidos que junto a los conjuntos residenciales basados en la vulgarización de los presupuestos del Movimiento Moderno, presentan la incidencia de grandes elementos infraestructurales, zonas industriales etc., en muchos casos ya en proceso de obsolescencia producto de la aceleración de la técnica, generando así un conjunto altamente heterogéneo y desestructurado.
