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New Investigations at Solunto (2022) ∙ The last fieldwork campaign in Solunto by the University of Palermo, in the sanctuary above the theatre and in the baths near the agora (the North Baths), obtained some relevant results concerning both the building sequences and the architectural configurations. In the sanctuary, a clearer picture is emerging of the oldest layout, dating from the 4th century B.C. (1st phase). After the first reshaping of the street grid and of the urban layout (2nd phase), in the second half of 2nd century B.C., an overall restyling (3rd phase) gave the whole sanctuary area an impressive organization into terraces linked through ramps and stairways. A striking feature, till now unnoticed, is the stairway aligned with the front of the temple with two cellae and forecourt, which enhances the theatre on its central axis; the theatre itself has a rectilinear analemma wall on the corresponding rear (W) part. In the baths, an eastern extension of the building has been discovered and some new evidence for the function of the complex has been obtained. At the same time, the virtual reconstruction project is being carried out, integrating the results from the fieldwork into the overall framework, with the twofold objective: to test the new acquisitions, and to create a virtual tour of the ancient city, allowing a “Solunto experience”.

The contribution concerns the study of Burri's famous work according to an archaeological approach.

In the second half of the second century BC, in the wake of the building renovation that affected the most important urban centers of northern Sicily, even the ancient city of Alesa Arconidea remodeled its monumental structure. The agora/forum, in particular, was restructured in a scenographic system, acquiring the architectural characteristics of a typical Hellenistic monumental complex, similar to those of Greece and Asia Minor, by which it was influenced. In planimetric terms, to date up to the present time, the agora represents a unicum in Sicily because of its Π shape with deep double columns of the arcade, which enclose a large square excluded to vehicular traffic. Recent researches and, above all, the survey of the architectural remains have provided new data that allow an updated reconstructive proposal. Fundamental, in this regard, was the contribution provided with the use of computer technologies through which the reconstructive study is no longer intended as a simple method of reconstruction and representation of an ancient artifact but as a methodology for confirmation and synthesis of analytic data related to the archaeological research.

The paper focuses on the strong connections between natural resources, environment, and urban development in the Hellenistic, Roman, and Byzantine city of Hierapolis of Phrygia (Pamukkale, Turkey). The ancient city was founded on a travertine terrace crossed by an active fault, responsible for impressive geothermal phenomena, i.e., flowing of thermal water, emission of gases, and frequent earthquakes, while the surrounding territory offered various stone qualities (travertine, alabaster, marbles, etc.). These environmental features affected the cultural identity of Hierapolis and its urban layout, conditioning also the construction techniques and the monumentalization of the city. In recent year, a multidisciplinary research has been performed, which saw the factual integration of archaeological, geo-archaeological, and archaeometric perspectives, in order to reconstruct how the natural resources and environmental phenomena impacted on the urban history of Hierapolis and the conservation of its monuments. The main methods for the reconstruction of the ancient landscape, the tectonic context, and the cityscape are discussed.

The contribution concerns the virtual reconstruction of the paintings of the Athlete's tomb in Ugento

This contribution presents the preliminary work, carried out over the past few months, concerning the reconstructive study of the paintings and mosaics of the Centennial House ", Insula IX-8, in Pompeii. In particular, the work focused on the decorated surfaces of 11 rooms located along the western part of the house, between the large central peristyle and the centenary alley. The different state of conservation of the paintings and mosaics made it necessary to use two different methods of digital intervention: the "virtual restoration" and the "virtual reconstruction". Both aim to reconstruct the initial condition of the appearance of the paintings at the time of their creation and use the tools of Information and Communication Technology (ICT) to obtain representations of the artefacts in their environmental context with extreme refinement of detail and consistency of the pictorial lexicon.

The contribution summarizes the activities of Archeology and Virtual Restoration carried out at the University of Salento between 2004 and 2018. In particular, the main research projects are illustrated: the Papyrological Museum of Lecce and the Soknopaiou Nesos Project, Dime es-Seba / Egypt (2013-2017); Hierapolis of Phrygia - Turkey (2005-2015) Virtual Hierapolis Project; Virtual restoration of the medieval paintings of Salento: knowledge-fruition-valorization (2004-2017).

Questa iniziativa editoriale è stata promossa in una versione ridotta nel libro Il teatro di Augusta Bagiennorum. Dallo studio dei resti all’ipotesi ricostruttiva del progetto architettonico. Il DVD porta a conclusione l’intero progetto di ricerca finalizzato alla restituzione dei principali edifici che furono realizzati nell’antica città romana proposta da Maria Cristina Preacco, funzionario della Soprintendenza per i Beni Archeologici fino al 2013.

Studio ricostruttivo dell'anfiteatro romano di Rudiae (Lecce)

A distanza di sei anni dal simposio internazionale tenuto a Mersin e intitolato “Olive oil and wine production in Anatolia during Antiquity”, che per la prima volta faceva il punto sullo stato delle conoscenze archeologiche riguardanti le attività produttive vinarie e olearie in Turchia tra l’epoca ellenistica e quella bizantina, il prosieguo delle ricerche a Hierapolis e nel suo territorio impone un aggiornamento e, soprattutto, consente di elaborare una tipologia dei principali macchinari utilizzati nei torcularia, specialmente presse e macine Six years after the international symposium held in Mersin and entitled "Olive oil and wine production in Anatolia during Antiquity ”, which for the first time focused on the state of the archaeological knowledge concerning the wine and olive oil production activities in Turkey between the Hellenistic and the Byzantine era, the continuation of research in Hierapolis and its territory imposes an update and, above all, allows the processing of a typology of the main machinery used in torcularia, especially presses and millstones

This paper illustrates the pursuance of the studies, focused on the initial phases of the Flavian Temple in Leptis, until 2014. The reconstructive hypothesis by the arch. Paolo Mighetto, based on the old and new archaeological data as result of excavations and researches in recent years, allow to publish the first 3d virtual rendering of the Roman Complex, made by Dr. Massimo Limoncelli, member of the Italian-Libian Archaeological Mission

Il Piemonte romano ha conservato i segni manifesti della grandiosità del programma edilizio avviato dall’impero di Augusto in numerose città di nuova fondazione. La mole del progetto di un teatro e di un anfiteatro ha richiesto l’impiego di materiale, tecnologia e risorse artistiche, nel cantiere antico, in quantità tali da conservarne nei secoli le testimonianze più eclatanti. E ha inciso a tal punto sul disegno delle città che, nonostante la spoliazione dei marmi decorativi e dei materiali da costruzione, se ne riconoscono talvolta i tratti nelle stratificazioni delle epoche successive. Giuseppe Assandria e Giovanni Vacchetta avviarono gli scavi nella piana della Roncaglia, frazione poco lontana dal centro della città di Bene Vagienna, a partire dal 1892 e portarono alla luce i resti di Augusta Bagiennorum, ponendo fine alle controversie sull’esatta ubicazione della città romana e della cui esistenza si erano formulate ipotesi fin dalla metà del Settecento. Nel 1894 individuarono i resti del teatro che Vacchetta immaginò e disegnò con la stessa enfasi con cui la cultura ottocentesca ritraeva la romanità classica. Gli scavi e i restauri ripresi a partire dagli anni cinquanta del Novecento dalla Soprintendenza alle Antichità del Piemonte mirarono a consolidare le sostruzioni della cavea e a riqualificare l’edificio scenico con un moderno palcoscenico ligneo e l’installazione di finti portali in cemento a imitazione di quelli in marmo lunense, oggi conservati nel locale museo archeologico insieme ai frammenti della decorazione architettonica scolpita nelle pietre tra le più belle e pregiate dell’Antichità . In anni recenti, le nuove indagini della Soprintendenza e la collaborazione iniziata con l’allora funzionario responsabile dell’area archeologica Maria Cristina Preacco hanno fornito interessanti risultati sulla provenienza dei materiali che, unitamente ai recenti studi multidisciplinari sulle scaenae frontes dei teatri romani, hanno incoraggiato l’elaborazione di una ipotesi ricostruttiva della scena prima e dell’intero edificio poi. Questo volume vuole dare continuità a un progetto di Maria Cristina, dedicato alla restituzione dei singoli monumenti che verosimilmente qualificarono Augusta Bagiennorum. Ci si è avvalsi delle tecniche grafiche proprie della progettazione architettonica nell’intento di ricostruire, più che l’edificio, il processo ideativo, nel rispetto delle fonti e della realtà archeologica, consapevoli che gli strumenti tradizionali della rappresentazione architettonica per alcuni versi sembrano avere esaurito la loro funzione comunicativa.

The virtual restoration, which focused only on the frescos of the southern wall, enabled to better understand the whole composition of the Genesis scenes and to formulate several hypothesis on the colours and their function as means of indirect lighting of the cave setting, scarcely lit itself

Il restauro virtuale è l’insieme di metodologie informatiche integrate di Computer Graphic, sia bidimensionali che tridimensionali,finalizzate alla restituzione di un bene archeologico, architettonico o artistico nella sua completa, o quasi, integrità. Questa nuova disciplina, che sta progressivamente affermandosi in ambito accademico, coniuga le attività e le metodologie di ricerca proprie delle cosiddette hard sciences con quelle più tradizionali di estrazione umanistica. Il virtuale è entrato a far parte della ricerca archeologica dapprima con un ruolo didattico-divulgativo (ricostruzioni ideali di edifici, città, territori ecc.), e, solo più recentemente, con fini conoscitivi, costituendo un aggiornamento dei tradizionali studi rivolti alla ricostruzione dei manufatti antichi. Per cui, in ambito archeologico, il restauro virtuale non deve essere inteso come modalità di ricostruzione ideale di un manufatto, bensì come metodologia per la verifica e la sintesi dei dati analitici. Il libro si rivolge a studenti di Archeologia, Storia dell’Arte e Restauro che intendano applicare le tecnologie informatiche ai propri settori di ricerca, introducendoli in maniera agile all’interno del vasto mondo del virtuale secondo un percorso metodologico comune.

Garbology, the science of finding stuff out about someone or something by digging through their trash, was invented in September 1970 by Alan Jules Weberman, a gadfly journalist who tried to unveil private secrets of Bob Dylan and his wife, the ex-bunny girl Sarah Lowndes, by searching the trash outside their Greenwich Village home in New York. Garbological applications to the Earth Sciences (“provenance analysis”) provide unique information on the hidden secrets of orogenic belts by scrutinizing the detritus they produce (“waste” in old geomorphological literature). This daring and exciting task requires painstaking dedication. First, we need to determine end-member signatures of “waste” shed by the diverse tectonic units incorporated in the mountain belt. This can be done only in modern settings and climatic conditions that grant minimum chemical weathering. Distortions of the original compositional signals by hydrodynamic processes need to be carefully checked and corrected for. Next, by combining the end-member signals as thus determined using forward modelling, we get a grasp of compositions expected to be found in the orogen’s garbage cans (“sedimentary basins”). The comparison between the expected and the observed may eventually lead us to decrypt the garbological record preserved in stratigraphic successions, and to unravel events the traces of which have long been erased by erosion from bedrock exposed in the thrust-belt. Simple statistical procedures allow us to interpret with a good amount of confidence information stored in recent deposits of the Pleistocene, but inferences become more and more uncertain when we try to extrapolate our knowledge of the present backwards in time to reconstruct sceneries of the remote past. By carefully checking diverse alternative hypotheses, however, garbologists may be of help to serious bedrock geologists to reconstruct with unsuspected precision the orogenic history of the Alps since the very beginning of convergence between Africa-Adria and Europe.

Detrital zircon fission-track analysis on modern sands is a valuable approach to constrain the pattern of erosional exhumation in orogenic source areas (e.g. Bernet et al., 2004). In order to constrain the short-term and long-term erosion pattern in the Alps-Apennines orogenic couple, we have collected samples of modern sands in selected sites of the Po River Delta, as well as along the Po River main trunk and in most of its tributaries. Zircon concentrates were separated according to a specific quantitative procedure coupled with sedimentological analyses, which allows an evaluation of zircon content in source rocks, of hydraulic sorting effects, and related intersample/intrasample zircon variability (Garzanti et al. 2008, 2009). Such analyses are the key point to perform sediment budgets and erosion-rate calculations starting from the identification of specific age population within grain-age distributions, and to constrain the short-term evolution of the belt thanks to the information stored in modern sediments.

Breve presentazione dei risultati del progetto storico ed archeologico presso il castello Carlo V di Lecce.

The contribution concerns the archaeological excavations conducted inside the church of Santa Maria della Strada in Taurisano (LE) carried out in May 2004 by the University of Lecce

Introduction to the pubblication: the idea of ​​the work was in fact that to reconnect objects, contexts and approaches to archeology e of contemporary art under the given common denominator from the belonging of the respective "types" of cultural assets to the contextualized heritage

Il testo, partendo da un inedito calco in gesso patinato della prima metà del ‘900 rinvenuto sul mercato antiquario, analizza il gruppo bronzeo con Eracle e la cerva di Cerinea del Museo Archeologico “A. Salinas” di Palermo da cui è tratto (fine I sec. a.C. – I sec. d.C.), descrivendone il tipo iconografico e individuandone l’archetipo lisippeo, attraverso il raffronto con esempi di età imperiale, tardo-antica e medievale. L’opera, ritrovata a Pompei nel 1805, fu donata al Museo dell’Università di Palermo nel 1831 per la munificenza dei Borbón/Farnese, di cui si approfondiscono almeno due episodi di illuminata committenza artistica per la città durante il soggiorno di Ferdinando I re delle Due Sicilie, riferiti all’iconografia erculea di tradizione familiare (Fontana con copia dell’Ercole Farnese “in riposo” alla Favorita [1802-1803] e decorazioni della “Sala d’Ercole” nel Palazzo Reale [1811-1812]). Noto tramite disegni e incisioni, il gruppo fin da subito riscosse un successo internazionale tra archeologi e conoscitori, tanto da richiedere calchi e riproduzioni in scala 1:1 o ridotta, alcuni dei quali oggi ancora rintracciati in gipsoteche e collezioni pubbliche e private in Italia e all’estero, o in vendita sul mercato dell’arte. The text, starting from an unpublished plaster cast of the first half of the '900 found on the antiquities market, analyzes the bronze group with Heracles and the Cerinea hind of the Archaeological Museum "A. Salinas" of Palermo from which it is taken (end of the first century BC - first century AD), describing the iconographic type and identifying the archetype by Lysippus, through the comparison with examples of imperial age, late antiquity and medieval. The work, found in Pompeii in 1805, was donated to the Museum of the University of Palermo in 1831 for the munificence of the Borbón/Farnese family, of which at least two episodes of enlightened artistic patronage for the city during the stay of Ferdinand I, King of the Two Sicilies, are explored, referred to the Herculean iconography of family tradition (Fountain with a copy of the Hercules Farnese "at rest" at the Favorita [1802-1803] and decorations of the "Hall of Hercules" in the Royal Palace [1811-1812]). Known through drawings and engravings, the group immediately enjoyed international success among archaeologists and connoisseurs, so as to require casts and reproductions on a 1:1 or reduced scale, some of which are still found today in gypsotheques and public and private collections in Italy and abroad, or for sale on the art market.

The aim of this paper is to compare different perceptions of cultural landscapes: the landscape of a Hellenistic-Roman city, Halaesa, reconstructed through archaeological surveys, and the contemporary landscape – natural and cultural – that characterizes the Tusa river, so-called “Fiumara d’arte”, where some installations of modern art have been made. Here the modern art is integrated with the landscape, in which it seems to emphasize some peculiar aspects, result of complex interactions. This analysis allow us to use the archaeological data to understand the relationship between human activities the symbolic aspects which connect ancient and modern communities to their territories.

The article puts in a sequence the ideas of wall, picture, frame, window, veil, screen and balcony in order to describe the process of "close range" spectacularisation whereby the gaze gives up the ancient landscape because it loves too much the modernity of "panorama".

Il contributo riflette sul ruolo cruciale della relazione tra antico e contemporaneo nella ricerca di Alberto Burri e si focalizza sul Grande Cretto di Gibellina come esempio di archeologia del futuro . A Gibellina Burri ricalca l’antico percorso della citt distrutta dal terremoto attuando un processo affine al restauro archeologico e conserva una traccia della topografia originaria attraverso le forme espressive contemporanee. Il suo approccio da archeologo va dunque inteso come presenza attiva dell’antico, capace di suggerire il dialogo tra la persistenza della storia, affidata alle aree archeologiche di Segesta e Selinunte, e la sua ferita, riscattata dall’arte contemporanea attraverso un’inedita risemantizzazione delle rovine. The contribution reflects on the crucial role of the relationship between ancient and contemporary in Alberto Burri's research and focuses on the Great Cretto of Gibellina as an example of the archeology of the future. In Gibellina Burri follows the ancient path of the city destroyed by the earthquake by implementing a process similar to archaeological restoration and preserves a trace of the original topography through contemporary expressive forms. His approach as an archaeologist must therefore be understood as an active presence of the ancient, capable of suggesting the dialogue between the persistence of history, entrusted to the archaeological areas of Segesta and Selinunte, and its wound, redeemed by contemporary art through an unprecedented resemantization of the ruins.

La ben nota statua seduta dell'«Aristotele» di Palazzo Spada (Roma) viene citata da Antonio Ciseri in una rappresentazione pittorica di un esule, che il pittore ticinese mette in scena come pensatore immerso in un paesaggio deserto. L'articolo ripercorre l'iconografia romantica del veggente in solitudine, mettendo le immagini in relazione con testi letterari e riflessioni sul ruolo politico che gli esuli svolgono nel giovane Regno d'Italia. The well-known seated statue of "Aristotle" in Palazzo Spada (Rome) is cited by Antonio Ciseri in a pictorial representation of an exile, which the Ticino painter depicts as a thinker immersed in a deserted landscape. The article retraces the Romantic iconography of the solitary seer, relating the images to literary texts and reflections on the political role played by exiles in the young Kingdom of Italy.

Dopo la conclusione della Prima Guerra Mondiale, tutti i comuni italiani cominciarono a erigere monumenti celebrativi in onore dei soldati morti nell’immane conflitto. Un aspetto meritevole di speciale attenzione, in queste opere commemorative, è l’utilizzo molto rilevante di forme ed elementi derivati dall’antichità greca e romana. Singole iconografie e singoli schemi tipologici, opportunamente rielaborati, potevano infatti adattarsi anche ai nuovi contesti celebrativi e ne rafforzavano il significato. La Sicilia sembra essere un buon case study per mostrare le potenzialità di un’analisi di questo genere: nei centri abitati di questa regione, come in tutto il territorio nazionale, sono presenti tantissimi monumenti dove appaiono introdotti motivi figurativi desunti dal mondo classico. Risultano di speciale interesse alcuni casi nei quali furono rielaborati non solo motivi generici, comuni a molti altri monumenti italiani, ma anche elementi tratti direttamente dalle testimonianze materiali dell’antichità conservate nell’isola. After the end of World War I, all the Italian municipalities began to raise commemorative monuments to the soldiers dead in the immense conflict. An aspect deserving of special attention, in these memorials, is the very considerable use of forms and elements derived from the Greek and Roman antiquity. Single iconographies and typological patterns, properly refashioned, could well fit these new celebratory contexts too and strengthen their meaning. Sicily seems to be a good case study to show the potential of such an analysis: in the towns of this region, as in the entire national territory, there is a great many monuments where we can recognize figurative motifs drawn from the classical world. Of special interest are some cases, in which not only generic motifs shared by many other Italian memorials were refashioned, but also elements directly derived from the material vestiges of the antiquities of the island.

A museum, whatever kind it is, is a complex machine machine that operates on a multiplicity of dimensions. A object of total communication one could define it, meaning that that if on the one hand it is built to show something and give show something and give information about what it shows, at the same time it is at the same time it is itself an entity that communicates. Not by chance contemporary museums are often ultra-expensive projects, housed in prestigious buildings designed by important architects and they are managed in every way as machines to produce profit, real places of hyper-consumption. It is perhaps the most strident contrast in the case of the museum: on the one hand, it is a cultural institution. on the one hand, it is a cultural institution dedicated to knowledge, on the other, a business. In both cases it is in competition, that is, it acts against something, be it another cultural institution or cultural institution or - more importantly - a body of widespread knowledge, with respect to which it produces some innovation.

The contribution concerns digital reconstruction as a method for the study of theatrical spaces from the archaic age to the imperial age. After some preliminary observations on the characteristics Structures of Greek and Roman scenic buildings, some case studies are presented, examples of an experienced working method. Case studies include ikria and ekklesiasteria of Metaponto (7th-5th century BC), the Greek theater of Metaponto (4th century BC), the Greek theater of Tindari (III-II century BC), the Roman theater of Augusta Bagiennorum (1st century AD), with an interesting status quaestionis on the state of the findings and the added value of accurate 3D reconstructions.

Detrital studies that utilize zircon U–Pb geochronology and fission-track (FT) thermochronometry are subject to a range of potential sources of bias that should be properly evaluated and minimized. Some of them are common to any single-grain mineral analysis (e.g., variable bedrock mineral fertility, hydraulic sorting during transport, selective grain loss during sample processing), whereas others are intrinsic to zircon, and are related to radiation damage and age discordance. In this article, we quantify the impact of intrinsic bias on detrital studies thanks to the analysis of modern detritus shed from the European Alps, and illustrate the general implications on geological interpretations. We show that detrital zircon U–Pb age distributions based on statistically robust datasets are highly reproducible and representative of the parent bedrock ages in the catchment. Arbitrary or selective removal of discordant grain ages can be minimized by using the Kolmogorov–Smirnov test to identify an appropriate cutoff level. Loss of metamict (α-damaged) zircon has a minor impact on data representativeness, and is mainly controlled by regional metamorphism rather than by mechanical abrasion during river transport. Zircon FT grain-age distributions were found to have poor reproducibility, although age spectra are consistent with bedrock data. However, unlike the U–Pb datasets, U-rich zircon grains (> 1000 ppm) are systematically missed, and undatable grains may exceed 50%. We identify two major sources of distribution bias specific to zircon FT datasets: (i) sediment sources dominated by U-rich zircon grains are markedly underrepresented in the detrital record, because such grains often have uncountable high densities of fission tracks (“U concentration bias”); (ii) sediment sources that shed zircon grains with high levels of α-damage are underrepresented, because these grains are lost during chemical etching for FT revelation (“etching bias”). In the case of multimethod dating on the same grains (e.g., FT and U–Pb double dating), bias affecting detrital zircon FT dating propagates to the entire dataset. These effects may not impact on exhumation-rate studies that utilize the youngest grain ages (i.e., lag-time approach). However, they represent a limiting factor for conventional provenance studies, and generally preclude application of zircon FT dating to sediment budget calculations.

Downstream changes of the geochronological signature in the Po drainage allow to assess the relative sediment contributions shed from the orogenic source areas, in order to constrain the short-term (100 to 10000 years) erosion pattern in the Alps-Apennines orogenic couple. In this perspective, we collected modern sands in selected tributaries draining the major tectonic units exposed in the orogen, as well as along the Po River trunk and in different sites of the Po Delta. Zircon concentrates were separated according to specific quantitative procedures coupled with grain-size and grain-density analyses, which provide an evaluation of zircon content in source rocks, of hydraulic sorting effects, and related intersample/intrasample zircon variability. Our methodological approach allows to perform sediment budgets and evaluate mineral content in diverse sediment sources (mineral fertility). Budget calculations were performed by investigating geochronological signals upstream and downstream of major confluences. We employed, LA-ICPMS U-Pb geochronology on detrital zircons, because this technique allows a full control of zircon populations during separation procedures and data analysis; we found, instead, that fission track dating on detrital zircon is affected and biased by selective grain loss. Results of U-Pb analysis performed on single grains show that all samples from the Po Delta yield similar grain-age distributions, and include grain-age populations that are rather constant both in age and size. Major peaks are found at ca. 30 Ma, ca. 280 Ma, and 400-500 Ma. Peaks in these distributions can be traced upstream up to their sources. The bulk of the geochronological signature of the Po Delta sands is displayed already upstream of the confluence of the Northern Apennines rivers, suggesting that short-term erosion rates were much lower in the Northern Apennine than in the Western and Central Alps. Age peaks typical of the eastern Lepontine dome also characterize the Apenninic tributaries, reflecting Oligo-Miocene sedimentary transfer from the Central Alps to the Adriatic foredeep, and next tectonic accretion of turbidite wedges to the Apennine belt. U-Pb analyses were complemented by zircon typology of the whole dataset, integrated by SEM observations on selected samples. Major typological groups can be traced from entry points in the Po Plain down to the Po Delta. Euhedral zircons are largely shed from the External Massifs (Mont Blanc and Argentera) and the Periadriatic plutons. Zircon grains showing signs of chemical abrasion, possibly acquired under high-grade metamorphic conditions, were detected in tributaries draining the Lepontine area.; Dans le bassin versant du Pô les modifications vers l'aval de la signature géochronologique permettent d'établir les contributions relatives des zones orogéniques sources, afin d'apprécier l'érosion à court terme (100 à 10000 ans) dans les Alpes et l'Apennin. Des sables ont été échantillonnés dans divers affluents du Pô, choisis selon les unités tectoniques qu'ils drainent, et le long du cours principal du Pô jusqu'à son delta. Les concentrés de zircon ont été extraits suivant des procédures définies, couplées à des analyses granulométriques et densimétriques de façon à évaluer la teneur en zircon des sources, les effets du tri hydraulique, comme les variabilités intra-échantillon et inter-échantillons. Cette approche méthodologique permet de réaliser des budgets sédimentaires et d'évaluer le contenu minéralogique des diverses sources (fertilité minéralogique). Les calculs de budgets ont été réalisés par la détermination du signal géochronologique à l'amont et à l'aval des confluents majeurs. Nous avons utilisé la géochronologie U-Pb par sonde à ablation laser couplée à un spectromètre de masse (LA-ICPMS) sur zircons détritiques, parce que cette technique permet un contrôle complet des populations de zircon pendant les procédures de séparation et autorise l'analyse des données; nous avons pu constater que la datation par traces de fission du zircon détritique, trop affectée par les pertes sélectives de grains, n'est pas adaptée à ce contrôle. Les résultats d'analyses U-Pb sur grains individuels montrent des distributions d'âges similaires pour tous les sables du delta du Po. Les pics majeurs de ces distributions, observés vers 30 Ma, 280 Ma et 400-500 Ma, peuvent être suivis vers l'amont jusqu'à leurs sources. L'essentiel de cette signature géochronologique existe déjà à l'amont de la confluence avec les rivières drainant l'Apennin septentrional. Ceci montre que l'érosion à court terme a été bien moindre dans l'Apennin que dans les Alpes occidentales et centrales. Les pics d'âges typiques de l'Est du dôme lépontin se retrouvent en outre dans les affluents issus de l'Apennin, reflétant un transfert sédimentaire ancien, à l'Oligo-Miocène, des Alpes centrales vers la paléo-fosse adriatique, suivi de l'accrétion de ces prismes turbiditiques à la chaîne de l'Apennin. Outre les analyses U-Pb, la typologie morphologique des zircons a été estimée grâce à des observations par microscopie électronique à balayage. Des groupes morphologiques peuvent être suivis depuis leur point d'entrée dans la plaine du Pô jusqu'au delta. Les zircons automorphes proviennent principalement du Mont Blanc, de l'Argentera (massifs cristallins externes) et des plutons périadriatiques. Des zircons portant des traces de corrosion chimique, peut-être acquises lors du métamorphisme de haute température, ont été trouvés dans les affluents issus du domaine lépontin.

Provenance studies based on detrital geochronological techniques are useful to investigate the present-day pattern of erosion in mountain belts (e.g. Carter and Bristow, 2000). In particular, LA-ICPMS U-Pb geochronology allows rapid generation of large datasets, and laser offers high spatial resolution for grains with complex age structure. The aim of this work is to investigate the downstream changes of detrital zircon U-Pb ages in the Po drainage, in order to constrain the short-term (10e2-10e4 a) erosion pattern in the Alps-Apennines orogenic couple. We collected samples of modern sands in selected tributaries draining the major tectonic units exposed in the orogen, as well as along the Po River main trunk and in different sites of the Po River Delta. Zircon concentrates were separated according to a specific quantitative procedure coupled with grain-size and grain-density analyses, which allows an evaluation of zircon content in source rocks, of hydraulic sorting effects, and related intersample/ intrasample zircon variability. Such analyses are crucial to perform sediment budgets and erosion-rate calculations based on single-mineral budgets. Preliminary results show that all samples from the Po Delta yield similar grain-age distributions, and include grain-age populations that are rather constant both in age and size. Peaks in the distribution can be traced upstream up to their source. Major peaks are found at ca. 30 Ma, ca. 280 Ma, and 400-500 Ma. Ages defining minor peaks cluster at 100-200 Ma and 500-700 Ma. The geochronological signature of the Po delta sands is essentially displayed already upstream of the confluence of the Northern Appennine rivers, suggesting lower short-term erosion rates in the Northern Apennine than in the Western and Central Alps. Age peaks typical of the eastern Lepontine dome characterize Apenninic tributaries, reflecting Oligo-Miocene sedimentary transfer from the Central Alps to the Adriatic foredeep, and next tectonic accretion of turbidite wedges to the Apennine belt. U-Pb analyses were complemented by zircon typology for the whole dataset, integrated by SEM observation on selected samples. Major typological groups can be traced from entry points in the plain down to the delta. Euhedral zircons are largely shed from the External Massifs and Periadriatic plutons. Zircon grains showing chemical abrasion, possibly acquired under high-grade metamorphic conditions, were detected in tributaries draining the Lepontine area. Carter A., and Bristow C., 2000. Detrital zircon geochronology: enhancing the quality of sedimentary source information through improved methodology and combined U-Pb and fission-track techniques. Basin Research, v. 12, 47-57.

This study examines the role of erosion on tectonic exhumation and deformation history of accretionary orogens. Our focus is on Taiwan, where interaction between active tectonics, earthquakes and cyclonic storms, are responsible for the highest erosion and deformation rates in the world. Two experiments are used to investigate the effects of erosion in the active bivergent orogenic wedge of Taiwan. The first model of thrust wedge without erosion is used as reference model. The second has been submitted to erosion under flux steady state conditions (1), to simulate an erosion pattern close to what is expected in Taiwan. First model shows the structure, morphology and evolution of classical high friction thrust wedges. Analytical measurements of the second model with high basal friction submitted to erosion, outline that the presence of weak layers (made with glass microbeads) that mimic décollements in the entering sequence, favors strain partitioning. Basal accretion of thrust units develops an antiformal nappe stack, whose growth and location is enhanced by erosion. A rapid uplift of underplated material occurs in the rear part of the wedge whereas frontal accretion characterizes the front of the growing prism. A zone of high exhumation develops in the retrowedge and migrates toward the backstop with continued shortening. This model is compared to the recent morphostructural evolution of Taiwan. In Taiwan, underplating characterizes the core of the orogenic wedge, where continental units from the subducting eurasian margin develops a regional scale antiformal nappe stack (in the Central Range), (2). Here, metamorphic rocks have been rapidly exhumed (in less than 4 Ma.) from depth of about 15 km due to combined effects of basal accretion and erosion. Our results emphasize the role of crustal décollements the internal dynamics of thrust wedge and how the coupling between tectonics and surface processes controls this dynamics, particularly the exhumation processes. References 1 – S.D. Willett, Brandon, M.T., 2002. Geological Society of America, v.30, no. 2, p. 175-178 2 – C.Y. Lu and Malavieille J., 1994. Earth Planet. Sc. Lett., v.121, p.477–494