Igor Maria Villa

Igor Maria Villa
Universität Bern | UniBe · Institute of Geological Sciences

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390
Publications
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Introduction
Igor Maria Villa currently works at the Institute of Geological Sciences, Universität Bern, and at the Centro Universitario Datazioni e Archeometria, Università di Milano Bicocca. Igor does research in Geochemistry and in Archeometry.
Skills and Expertise

Publications

Publications (390)
Article
An accurate record of preindustrial (pre-1900 CE) sea level is necessary to contextualize modern global mean sea level (GMSL) rise with respect to natural variability. Precisely dated phreatic overgrowths on speleothems (POS) provide detailed rates of Late Holocene sea-level rise in Mallorca. Statistical analysis indicates that sea level rose local...
Preprint
Deformation of polymineralic aggregates can be accommodated by viscous granular flow, a process mediated by the interplay among intracrystalline plasticity and dissolution–precipitation, each active in specific minerals at given P–T conditions. Common rock-forming minerals like quartz, feldspars and sheet silicates have been intensively studied in...
Article
Full-text available
Dating deformation is difficult, as textures and petrogenesis of deformed rocks are complex. Moreover, geochronometer categories are pursued by communities that often do not communicate. Hygrochronology dates the retrograde metasomatic/metamorphic reactions caused by aqueous fluid circulation events. Thermochronology models time-temperature histori...
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Radiogenic strontium isotopes (87 Sr/ 86 Sr) of vein carbonates play a central role in the tectono-metamorphic study of fold-and-thrust belts and accretionary wedges and have been used to document fluid sources and fluxes, for example, along major fault zones. In addition, the 87 Sr/ 86 Sr ratios of vein carbonates can trace the diagenetic to metam...
Article
The Bressanone (Brixen) pluton, cropping out at the culmination of the Southalpine indenter between the North Giudicarie and the Pustertal-Gailtal faults, is mainly composed of Permian granodiorite to granite, with minor gabbros and diorites in its southern part. New U–Pb SHRIMP zircon ages reveal two distinct crystallization episodes at 289.7 ± 3....
Article
This paper represents the first systematic Pb isotope investigation of Italian Medieval coins and aims to provide new parameters for a general historical interpretation of coin production and circulation in Medieval Europe. We collected more than one hundred specimens, minted in a period between 9th − 14th centuries AD and coming mostly from archae...
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Thirty-nine Neolithic and Early Bronze Age copper objects (primarily axe blades and daggers) from Central, southern and eastern Switzerland or eastern France were analysed typochronologically, chemically and with regard to their lead isotope ratios. This combination of methods allows for more differentiated and reliable conclusions about the proven...
Article
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Lead isotope compositions were determined for 18 metal objects from the archaeological site of Sant’Imbenia, NW Sardinia, dating to the end of the ninth century BCE onwards. The provenance of some objects is unambiguously traced to SW Sardinia; other objects could derive either from central Sardinia or the Iberian coastal ranges. The variety of the...
Article
Medieval pavements composed of lead-glazed tiles decorated with a variety of techniques continue to inspire questions about the organisation of glaze manufacture, and the supply and origin of lead materials. The tiles analysed in this study are from Suscinio I (a 13th-century pavement) and Suscinio II (a 14th-century pavement), at the Château of Su...
Article
The release of Ar during stepwise heating ³⁹Ar⁴⁰Ar dating experiments may be controlled by Fick's Law diffusion in an inert matrix, and/or by structural modifications of the host mineral. A ca. 1 mm³ irradiated cleavage fragment of a low sanidine crystal from Itrongay, Madagascar was degassed isothermally at 888 ± 2 °C for 264 h, acquiring 67 stepw...
Article
Multiple sulfur (δ³⁴Ssulfate, Δ³³Ssulfate, & Δ³⁶Ssulfate), nitrogen and oxygen (δ¹⁵Nnitrate & δ¹⁸Onitrate) and strontium (⁸⁷Sr/⁸⁶Sr) isotope compositions of precipitation collected from Seoul, South Korea were analyzed to study the sources, transportation and deposition of air pollutants in East Asia. The δ³⁴Ssulfate values (from 1.9 to 14.6‰ with...
Article
Dating structurally complex fault rocks often results in internally inconsistent ages, as several mineral generations are intergrown at scales << 10 µm and almost always altered to various degrees. Firstly, electron probe microanalysis is necessary to assess both inventory and spatial distribution of minerals and their retrogression/alteration phas...
Article
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Museum-grade mica megacrysts of the Phalaborwa phlogopite (ca. 2 Ga) and the Rubikon pegmatite (ca. 0.5 Ga) were screened for intra-grain compositional and chronological heterogeneities by electron probe microanalysis and ⁴⁰Ar/³⁹Ar dating, respectively. Both micas were known to have RbSr ages indistinguishable from UPb ages. Even though step heatin...
Article
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Epidote-here defined as minerals belonging to the epidote-clinozoisite solid solution-is a low-µ (µ = 238 U/ 204 Pb) mineral occurring in a variety of geological environments and participating in many metamorphic reactions that is stable throughout a wide range of pressure-temperature conditions. Despite containing fair amounts of U, its use as a U...
Article
The degree of early Archean terrestrial differentiation into mantle and crust is long debated. A number of studies rely on bulk rock Hf and Nd isotope data to gain further insight. Here we present HfNd data from two igneous basements suites of Barberton Mountain Land, namely a tonalite-trondhjemite-granodiorite (TTG) and granodiorite-granite-monzog...
Article
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The systematics of Ar release during in vacuo stepwise heating of hydrous minerals is examined. By means of common-denominator three-isotope correlation diagrams, in use for 60 years, it is possible to recognize the presence of polymineralic mixtures in a step-heated mineral separate and characterize their components. This data presentation, when a...
Article
The study of a huge repertory of sparse glazed ware from Donoratico (Livorno, Italy) dated back to the 9th century was carried out to investigate the production technology via petrographic, chemical and isotopic investigations. The mineralogical and chemical evidence suggested the application of a lead oxide flux to an unfired non‐calcareous cerami...
Preprint
Full-text available
Monoclinic epidote is a low-µ (µ = 283U / 204Pb) mineral occurring in a variety of geological environments, participating in many metamorphic reactions and stable throughout a wide range of pressure–temperature conditions. Despite containing fair amounts of U, its use as a U–Pb geochronometer has been hindered by the commonly high contents of initi...
Article
Two-mica—biotite and muscovite—volcanics are particularly rare in the geological record. One of the several dozen volcanic ash layers from Central Andes volcanoes found in the upper Miocene marine succession of the Pisco Formation (Ica Desert, Peru) contains juvenile biotite and muscovite, sillimanite/andalusite, feldspars, and rhyolitic glass. 39A...
Article
The IUPAC-IUGS joint Task Group “Isotopes in Geosciences” recommends a value of (106.25 ± 0.38) Ga for the half-life of ¹⁴⁷Sm, and a corresponding decay constant λ147 = (6.524 ± 0.024) × 10⁻¹² a⁻¹, both with a coverage factor k = 2. For the extinct radionuclide ¹⁴⁶Sm two very different half-lives are used in the scientific community (c. 68 and 103...
Article
The Janggun lead-zinc-(silver) deposit in South Korea was formed by hydrothermal-metasomatic processes. We collected 12 samples over a 100m transect in one of the five orebodies recognized in the deposit and analyzed a total of 68 sulfide minerals. Detailed mineralogical observations show successive modifications and overprint of pristine sulfide b...
Chapter
The mass balance of molybdenum (Mo) was studied in the Strengbach catchment. Monitoring of rainfall, vegetation, and soil characteristics in this 0.8 km2 catchment was started decades ago. We present Mo concentrations and isotope compositions of about 60 samples including bedrock types, perennial springs, soil profiles, roots and leaves, and the ou...
Article
Strata of Chilcatay and Pisco formations exposed in the Ica Desert (East Pisco Basin, southern Peru) preserve one of the most complete and rich records of Miocene marine vertebrates of the world. Despite its exceptional importance, the chronostratigraphy of these fossil-bearing deposits has been only sporadically studied in the literature until rec...
Article
Vorticity estimates based on porphyroclasts analysis is limited by the extrapolation to three dimensions of two-dimensional data. We describe an 3D approach based on the use of X-ray micro-computed tomography that better reflects the real 3D geometry of the porphyroclasts population. This new approach for kinematic vorticity analysis in the Munsiar...
Cover Page
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GSL481 on Crustal Architecture and evolution of Himalaya-Karakoram-Tibet Orogen is a new book release of Geological Society of London, Special Publication
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Microscale oxygen isotope analysis (¹⁸O/¹⁶O) of minerals can identify distinct events of fluid-rock interaction. This method is, however, still limited to a few major and accessory minerals of which most are anhydrous minerals. We present the systematic study of oxygen isotope distribution in white mica by Secondary Ion Mass Spectrometry (SIMS). Te...
Conference Paper
Tephra fingerprinting is a unique tool for reconstructing a high resolution stratigraphy (Lowe, 2011; Smith et al., 2011). In the upper Miocene succession of the Pisco Formation (East Pisco Basin, Peru) the presence of distal volcanic ashes from the Central Andes represents a great opportunity for dating and correlating stratigraphic sections at di...
Article
Full-text available
To address the problems pertaining to the geodynamic evolution of the Himalaya-Karakoram-Tibet (HKT) system, and of its past and present orogenesis, the present volume includes a broad selection of contributions, which use both field and laboratory approaches to multiple disciplines such as structural geology, tectonics, petrology, mineralogy, petr...
Article
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Eocene dykes extending over 50 km along the southern margin of the Ladakh batholith (NW India) fall into two main groups showing different orientations, as well as different isotope and trace element geochemistry. Both dyke families formed in the same tectonic setting over a time span of approximately 4 Ma. However, each family is far from monolith...
Article
U-Th-Pb petrochronology is based on the incontrovertible fact that the diffusion of radiogenic Pb is negligibly small relative to retrograde reaction rates. Multi-element maps demonstrate that patchy textures tightly correspond to (U + Th)-Pb age variations, requiring that fluid-induced dissolution/ reprecipitation is the principal cause of Pb mobi...
Article
The timing of shearing along the Vaikrita Thrust, the upper structural boundary of the Main Central Thrust Zone in the Garhwal Himalaya, was constrained by combined microstructural, microchemical and geochronological investigations. Three different biotite–muscovite growth and recrystallization episodes were observed: a relict mica-1; mica-2 along...
Article
Tephra layers are a unique tool for stratigraphy. Their geologically instantaneous deposition across wide areas makes them a powerful instrument for dating and correlating distant localities. In this paper, we apply tephra fingerprinting for high-resolution stratigraphic purposes in the upper Miocene portion of the Pisco Formation, which crops out...
Chapter
The Colline Metallifere district (near Massa Marittima, southern Tuscany) hosts a number of Cu-Pb-Zn (Ag) vein deposits which fed a long-living mining and metallurgical industry. According to archaeological and historical documents, in the Middle Ages (11th–14th century) metal production in the district was mainly purposed for coinage. In this comm...
Article
Mass spectrometers are designed to measure ratios between isotopes and elements. Current archeometric research employs various instrumental designs: gas mass spectrometers, thermal ionization mass spectrometers, accelerator mass spectrometers, and plasma source mass spectrometers. Design features go hand in hand with the specific class of problems...
Article
Full-text available
This paper is the first integrated account of the sedimentology, stratigraphy, and vertebrate paleontology for the marine strata of the Chilcatay Formation exposed at Ullujaya, Pisco basin (southern Peru). An allostratigraphic framework for the investigated strata was established using geological mapping (1:4000 scale) and conventional sedimentary...
Article
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An unusual cave is located in the hills southeast of the town of Thabazimbi in the Limpopo Province. This cave, a V-shaped shallow chamber measuring 110 × 40 m, was discovered serendipitously when an adit was driven into the hill in connection with iron ore mining. It has no natural entry point and no externally derived sediment is found in it. It...
Article
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The taphonomy and palaeoecology of the early Miocene (Burdigalian) vertebrate assemblage of Ullujaya (East Pisco Basin, Peru) is here described. Vertebrate remains are concentrated in marine facies (Ct1a association) of the exposed Chilcatay Formation (dated 19–18 Ma) deposited within a 30–40 m deep, semi-enclosed, offshore environment. Coupled wit...
Article
Protohistoric metal objects coming from the archaeological sites of Pontecagnano (Salerno, Italy) and Striano (Naples, Italy), preserved in the Pontecagnano National Archaeological Museum and the Paleontological Museum of Naples University “Federico II” have been studied by means of an archaeometric approach. A multi-analytical procedure including...
Article
The Etruscan site of Populonia-Baratti (Southern Tuscany, Italy) became in the first millennium BCE one of the most important iron metalworking sites in the Mediterranean region thanks to the exploitation of nearby Elba Island iron ores. Recent studies, however, have demonstrated that, before iron, copper was smelted therein (9th–8th century BCE)....
Article
The Jurassic clay-rich aquitard sequence underlying the Swiss Molasse Basin is locally penetrated by unusually frequent veins consisting of calcite ± celestite, in particular in the Schlattingen-1 and Oftringen drill cores. The veins are linked to extensional brittle structures, with shear senses ranging between dip-slip and strike-slip. Deformatio...
Article
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The South Asian river dolphin (Platanista gangetica) is the only extant survivor of the large clade Platanistoidea, having a well-diversified fossil record from the Late Oligocene to the Middle Miocene. Based on a partial skeleton collected from the Chilcatay Formation (Chilcatay Fm; southern coast of Peru), we report here a new squalodelphinid gen...
Article
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In the Garhwal Himalaya, the Malari granite, a small pluton, intrudes the upper portion of the Greater Himalayan Sequence (GHS) and is deformed in the South Tibetan Detachment System (STDS) shearing. In the present work, we undertook a multidisciplinary approach involving microstructural, chemical and geochronological analyses of the samples in ord...
Article
The Cristal Zn prospect consists of a mixed sulfide and nonsulfide mineralization located in the Bongará province (Amazonas region, northern Peru). The mineralization is hosted by carbonate rocks of the Pucará Group, deposited in a Mesozoic extensional basin on the western margin of the Brazilian-Guyana shield. Zinc sulfides at Cristal occur in the...
Article
We present a new interpretation of the Bashgumbaz Complex (BSC), a fragment of a large mafic-ultramafic nappe exposed along the Alichur Valley in the Pamir, whose significance is of paramount importance for the understanding of the Cimmerian orogeny in South Pamir. The BSC is exposed along the contact between the SE and SW Pamir and consists of a l...
Article
A literature survey reveals that the K-Ar chronometer gives ages that are ca. 1% younger than U-Pb ages. This offset is generally attributed to an inaccurate 40K decay constant. Three geological samples selected from a shortlist of eight with known U-Pb ages were investigated using detailed petrological methods and subsequently the Rb-Sr and K-Ca c...
Article
Full-text available
Observations of discordant ages, meaning that an age given by one mineral geochronometer is different from the age given by another geochronometer from the same rock, began in the early days of geochronology. In the late 1950s and 1960s, discordant U-Pb zircon ages were unquestioningly attributed to Pb diffusion at high temperature. Later, the mine...
Data
This paper presents a study carried out on the origins of two groups of lead sling projectiles accidentally recovered in the Dobrudja territory, attributed to the Macedonian and Roman armies, respectively. The analytical methods used were Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for trace element analyses and Multi Collector Inductivel...
Article
At active volcanoes, petrological studies have been proven to be a reliable approach in defining the depth conditions of magma transport and storage in both the mantle and the crust. Based on fluid inclusion and mineral geothermobarometry in mantle xenoliths, we propose a model for the magma plumbing system of the Island of El Hierro (Canary Island...
Conference Paper
Full-text available
The paper reports a chemical and minera¬logical characterization of some metallic artefacts from two Campanian protohistoric archaeological sites. The first group of samples, mainly dated to Iron Age, is preserved in the Archaeological Museum of Pontecagnano (Salerno, Italy). A second group of coeval metallic objects, preserved at the Paleontologic...
Article
The Mio-Pliocene Pisco Formation, Peru, is a world renowned Konservat-Lagerstätte. Beside its potential in preserving important information on the history of the Pacific Ocean during the Miocene, the Pisco Fm. provides palaeontologists with the unique opportunity to study in detail the evolution of marine vertebrate fauna during the Neogene. Becaus...
Article
The Sangdong scheelite-molybdenite deposit in northeast South Korea consists of strata-bound orebodies in intercalated carbonate-rich layers in the Cambrian Myobong slate formation. Among them, the M1 layer hosts the main orebody below which lie layers of F1-F4 host footwall orebodies. Each layer was first skarnized with the formation of a wollasto...
Conference Paper
The Singhbhum Craton in eastern India has extensive occurrences of Paleoarchean crust and is of potential geological significance for Archean crust-mantle evolution studies. The granites and TTG show enriched LREE and depleted HREE pattern which is typical for Archean upper crust. Lead isotopes from leached K-feldspar mineral separates from differe...
Article
Detrital thermochronology is often employed to assess the evolutionary stage of an entire orogenic belt using the lag-time approach, i.e., the difference between the cooling and depositional ages of detrital mineral grains preserved in a stratigraphic succession. The impact of different eroding sources to the final sediment sink is controlled by se...
Conference Paper
Full-text available
The Main Central Thrust (MCT) is a first-order tectonic discontinuity that divides the Greater Himalayan Sequence, the metamorphic core of the belt, in the hanging-wall, from the Lesser Himalayan Sequence in the footwall. Contrasting criteria have been proposed to define the location of the MCT and to study its evolution [1-3]. As different studies...
Article
Full-text available
25 years after the discovery in theÖtztal Italian Alps, the 5,300-year-old mummy keeps providing key information on human biological and medical conditions, aspects of everyday life and societal organization in the Copper Age. The hand axe found with the body of the Alpine Iceman is one of the rare copper objects that is firmly dated to the early C...
Conference Paper
Full-text available
Geodynamic models of the lithosphere require quantitative data from natural samples. Time is a key parameter: it allows to calculate rates and duration of geological processes and provides informations about the involved physical processes (Vance et al. 2003). Large-scale orogenic models require linking geochronological data with other parameters:...
Conference Paper
The upper Miocene Pisco Formation (Peru) represents a world-known fossil Lagerstätte containing abundant and exceptionally well-preserved marine vertebrates. A detailed chronostratigraphic reconstruction is indispensable to study this fossil record and to understand the evolution of marine vertebrates. Recent work (Bianucci et al., 2016; Di Celma e...