Gli effetti antropici nell’evoluzione storica della costa “Picena”

The historical evolution of the southern Marche shoreline (between the Conero promontory and the Tronto R. mouth) has been investigated comparing it with both natural and anthropic changes. The study started searching, georeferencing and digitizing in a GIS environment all the available historical maps and the observations deriving from archeological and documental findings, in order to reconstruct the position of the shoreline at different times, mostly for fluvial mouths. This allowed us to highlight that for the last two millennia anthropic interventions influenced coastal dynamics more than climate variations. For all the investigated sites a close relation between shoreline fluctuations and forestation/deforestation processes was clearly revealed. Among others, it emerged that river mouths progradation continued up to 1930, well after the end of the “Little Ice Age” (around 1850). The above relation is particularly striking for the last two centuries, for which we have both accurate maps and census of forested areas. During the XIX century, notwithstanding the warm climate favored slope protection, widespread deforestation resulted in a regular advance of shorelines (average rate about 4.95 m/y for the first half of the century and 1.08 m/y for the second half). The XX century featured a more irregular behavior with substantial retreat after the ‘30s: this derives almost exclusively from anthropic interventions in the river basins (construction of dams, river bed quarrying, river reshaping, abandonment of crops etc.) leading to a severe decrease of solid load. For the last few decades and at present, the most important factors driving the behavior of coastlines resulted to be the various interventions carried out along the beaches and in front of them to reduce erosion. Keywords: antropogenic impact, historical evolution, coastline, central-southern Marche, Adriatic Se

Tendenza evolutiva della spiaggia della Riserva Naturale della Sentina (San Benedetto del Tronto, AP)

Abstract The Regional Natural Reserve “Sentina” stretches itself for some 1.7 km along the southernmost end of the littoral area of San Benedetto del Tronto (AP) at the boundary with Abruzzo; it hosts one of the very few costal dunes still preserved in the Marche Region. Its gravelly-sandy beach in still natural, but is bound to the north by a long series of emerged barriers and to the south by a long (more than 300 m) pier; these structures noteworthy influence the retreat of the shoreline. In the area, a long monitoring (starting from 2000) has been carried out in order to interpret and quantify the modification occurred on both the emerged and submerged beach. During this time span, the shoreline retreated every year: up to 2006 its retreat has been evaluated in 27.7 m, with a local maximum of 33.5 m, whilst for the following 6 years (notwithstanding an artificial nourishment in 2008) it continued to retreat by 22.2, as an average. Therefore, in 12 years wave erosion resulted in some 50 m of backing; this also implied the loss of about 42’000 m2 of coastal dunes. Therefore, it is logical to assume that if no relevant intervention will be carried out, standing the almost absent nourishment deriving from the solid load of the Tronto R., in the next future the Sentina area will suffer progressive coastal erosion, with severe backing of the shoreline and distruction of the coastal dunes. Keywords: coastal erosion, monitoring, “Sentina” Reserve, coastal dune

Stratigraphic framework of the late Miocene Pisco Formation at Cerro Los Quesos (Ica Desert, Peru)

The enormous concentration of marine vertebrates documented within the Pisco Formation is unique for Peru and South America and places this unit among the prime fossil Lagerstätten for Miocene to Pliocene marine mammals worldwide. In order to provide a robust stratigraphic framework for the fossil-bearing locality of Cerro Los Quesos, this study presents a 1:10,000 scale geological map covering an area of about 21 km2, a detailed measured section spanning 290 m of strata, and a refined chronostratigraphy for the studied succession well constrained by diatom biostratigraphy and high-resolution 40Ar/39Ar isotopic dating of three interbedded ash layers. Within the apparently monotonous, diatomite-dominated sedimentary section, the Pisco Formation has been subdivided into six local members, with stratigraphic control over the different outcrops facilitated by the establishment of a detailed marker bed stratigraphy based on fifteen readily distinguishable sediment layers of different nature

Sequence response to syndepositional regional uplift: insights from high-resolution sequence stratigraphy of late Early Pleistocene strata, Periadriatic Basin, central Italy.

This paper deals with the depositional sequences that occur within the uppermost part of the Plio–PleistocenePeriadriaticbasin fill in the southern Marche region, centralItaly. The succession is an EarlyPleistocene, easterly dipping clastic wedge showing an overall shallowing trend from slope clays to shallow-marine and non-marine deposits comprising two major sequences, namely Qmb and Qmc. Analysis has provided new insights into: (i) the nature of sedimentary facies and facies associations occurring within the upper part of Qmb and Qmc; (ii) the gradual contact within Qmb between regressive littoral deposits (RLD) and underlying deep-marine blue clays; (iii) the composite origin of the Emilian surface, which is a widespread erosional unconformity separating Qmb from Qmc; (iv) the cyclothemic pattern of Qmc, composed of downstepping, small-scale depositional sequences; (v) the role played by synsedimentary uplift on the stacking pattern of small-scale sequences and their internal architecture.Up to three small-scale depositional sequences have been recognised within Qmc. They are up to 50 m thick and defined by previously unrecorded. High-frequency sequences display a distinctive stacking pattern and form a tectonically induced forced regressive sequence set underlain by a composite, tectonically enhanced regressive surface of marine erosion formed by the lateral connection of lower-rank sequence boundaries

Considerazioni sull’utilizzo delle sabbie dragate al largo di Civitanova Marche (Adriatico centrale) per il ripascimento delle spiagge.

Sono state analizzate le principali caratteristiche dei sedimenti dragati al largo di Civitanova Marche (Adriatico centrale), confrontandole con quelle degli arenili delle Marche meridionali al fine di evidenziare la lor compatibilità. Particolare attenzione è stata dedicata all'analisi del sito di Marina Palmense (Comune di Fermo) in cui nel luglio 2007 il materiale dragato è stato utilizzato per un primo ripascimento. Dallo studio è risultata l'incompatibilità dei materiali dragati con la dinamica costiera lungo quasi tutto il tratto investigato, compreso quello già sottoposto a rifluimento, dimostratosi inefficace

External controls on internal organization and vertical stacking pattern of Pleistocene shallow-marine and fluvial depositional sequences

The complex interaction of regional uplift, glacio-eustasy, local tectonics, and sediment supply has a significant impact on the internal architecture and vertical arrangement of shallow-marine and fluvial depositional sequences and can be documented in well-exposed successions of Pleistocene strata cropping out along the uplifted margins of Ecuador, northern Chile, and eastern central Italy. The results stemming from these sediments have important implications for sequence stratigraphic models in tectonically active areas and lead to the following general conclusions: (i) given that rates of syndepositional regional tectonic uplift were substantially less than rates of contemporaneous eustatic changes in sea level in all of the study areas, glacio-eustasy appears to have played the main control on development of high-frequency sequences; (ii) stratal geometries, sedimentary facies, and genetic complexity of sequence bounding unconformities of these cyclic successions indicate that the internal organization of individual depositional sequences is directly controlled by the rates of sediment supply and by the occurrence of intrabasinal, short-term normal faults striking obliquely with respect to paleo-shoreline trends; (iii) the effects of the regional tectonic uplift on these eustatic sequences is on longer term, at sequence set scale, and is responsible for their distinctive stacking pattern; owing to the progressive, tectonically driven reduction of accommodation space, high-frequency sequences are nested within a forced regressive sequence set, where each successively younger sequence is displaced basinward and downward respect to the last

Off-shelf sedimentary record of recurring global sea-level changes during the Plio-Pleistocene: evidence from the cyclic fills of exhumed slope systems in central Italy

The markedly cyclic sedimentary successions of four late Pliocene to early Pleistocene slope turbidite systems exposed in eastern central Italy have been resolved into 31 high-frequency sequences. Chronological constraints from biostratigraphy and magnetostratigraphy indicate that these successions form a composite, partially overlapping stratigraphic record and sequence-bounding surfaces can be convincingly correlated with glacial oxygen isotope stages G2–60 (c. 2.65–1.7 Ma) inclusive. The studied successions, therefore, preserve an extraordinary and legible record of recurring, orbitally dictated glacio-eustatic sea-level fluctuations and provide an unprecedented opportunity to examine the deep-water sedimentary response to such high-frequency changes from an outcrop perspective