Pierre Lanari

Universität Bern | UniBe · Institute of Geological Sciences

XMapTools is a MATLAB©-based graphical user interface program for electron microprobe X-ray image processing, which can be used to estimate the pressure–temperature conditions of crystallization of minerals in metamorphic rocks. This program (available online at http://www.xmaptools.com) provides a method to standardize raw electron microprobe data...

We present a new thermodynamic activity-composition model for di-trioctahedral chlorite in the system FeO–MgO–Al2O3–SiO2–H2O that is based on the Holland–Powell internally consistent thermodynamic data set. The model is formulated in terms of four linearly independent end-members, which are amesite, clinochlore, daphnite and sudoite. These account...

Above subduction zones, magma production rate and crustal generation can increase by an order of magnitude during narrow time intervals known as magmatic flare-ups. However, the consequences of these events in the deep arc environment remain poorly understood. Here we use petrological and in-situ zircon dating techniques to investigate the root of...

The knowledge of the fractionation behaviour between phases in isotopic equilibrium and its evolution with temperature is fundamental to assist the petrological interpretation of measured oxygen isotope compositions. We report a comprehensive and updated internally consistent database for oxygen isotope fractionation. Internal consistency is of par...

This paper introduces the software solution Bingo‐Antidote for thermodynamic calculations at equilibrium based on iterative thermodynamic models. It describes a hybrid strategy combining the strength of Gibbs energy minimization (GEM) and inverse thermobarometry models based on the comparison between the modelled and observed mineral assemblage, mo...

Crystallization-differentiation of magmas and/or fluid migration in arc settings are important drivers of stable-isotope fractionation of elements like titanium and molybdenum. For both isotope systems, evolved magmas are heavier than average arc-basalts, which requires an isotopically light reservoir counterbalancing the heavy felsic lithologies....

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 under given P–T conditions. Some rock-forming minerals like quartz and feldspars have been intensively studied in terms of deforma...

Understanding mass transfer associated with fluids circultion and deformation in the Alpine orogeny is often complex due to common multistage crystallization. For example, in two emblematic and historic Pb-Ag deposits of the French Alps, Macôt-la Plagne (MP) and Peisey-Nancroix (PN), a sedimentary or orogenic origin is still debated. To discriminat...

Hydrothermal fluid-flow in orogenic belt is currently of great interest for the development of geothermal energy. Crustal-scale fluid-flow is related to deep fault-zones that localize deformation and fluid/rock interactions including mineralogical transformations and precipitations. Phyllosilicates are common minerals found in hydrothermal systems...

Hydrothermal fluid-flow in orogenic belt is currently of great interest for the development of geothermal energy. Crustal-scale fluid-flow is related to deep fault-zones that localize deformation and fluid/rock interactions including mineralogical transformations and precipitations. Phyllosilicates are common minerals found in hydrothermal systems...

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...

Mafic eclogites are found in many orogens as lenses embedded in quartzo‐feldspathic migmatites. These high‐pressure relics are interpreted either as remnants of ancient sutures and thus formed during oceanic subduction, or as fragments of lower crust exhumed from the root of orogenic thickened crust. It is critical to distinguish between these two...

We use a combination of several in situ techniques to assess the P‐T‐t path of high‐pressure granulites from the Passos Nappe in the Southern Brasília Orogen (SE ‐ Brazil). Quantitative element mapping and single‐element thermometers (Zr‐in‐rutile and Ti‐in‐quartz) are coupled with P–T pseudosections and monazite and rutile dating. Compositional an...

Dehydration reactions in the subducting slab liberate fluids causing major changes in rock density, volume and permeability. Although it is well known that the fluids can migrate and interact with the surrounding rocks, fluid pathways remain challenging to track and the consequences of fluid-rock interaction processes are often overlooked. In this...

Collisional orogens commonly include mono-metamorphic and poly-metamorphic units, and their different evolution can be difficult to recognise and reconcile. The Theodul Glacier Unit (TGU) in the Western Alps consists of an association of metasedimentary and metamafic rocks embedded within the Zermatt-Saas tectonic unit. In spite of recent petrologi...

The Cima Lunga unit in the Central Alps is dominated by quartzofeldspathic gneisses with subordinate mafic, ultramafic, and metacarbonate rocks. Only mafic and ultramafic lithologies were thought to preserve clear evidence of Alpine high-pressure metamorphism. This led to the questions of whether the different rock types were subducted and exhumed...

The Borborema Province (NE-Brazil) experienced widespread intracontinental deformation associated with low-pressure metamorphism during the Neoproterozoic-Cambrian assembly of West Gondwana. The widespread intracontinental deformation was driven by tectonic stresses derived from two continental collisions reported in the literature at ca. 630–610 M...

Terrestrial and extraterrestrial rocks exhibit significant mass-dependent Ti isotopic variations, with basalts being isotopically lighter than evolved lithologies. The observed trend from light to heavy Ti isotopic compositions from more primitive to more differentiated rocks agrees with theoretical predictions that light Ti isotopes are sequestere...

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...

Epidote – here defined as minerals belonging to the epidote–clinozoisite solid solution – is a low-μ (μ=238U/204Pb) 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−...

Modern-style plate tectonics, often characterised by subduction, is a fundamental dynamic process for planet Earth. Subduction related eclogites are widely used to indicate initiation of plate tectonics or whether different tectonic regimes dominated Earth history. However, such markers are commonly overprinted in ancient metamorphic terranes and r...

An amendment to this paper has been published and can be accessed via the original article.

Microscale dating of distinct domains in minerals that contain relics of multiple metamorphic events is a key tool to characterize the polyphase evolution of complex metamorphic terranes. Zircon and allanite from five metasediments and five metaintrusive high-pressure (HP) rocks from the Eclogite Micaschist Complex of the Sesia Zone were dated by S...

The pre-Alpine history of the Venaco-Ghisoni Unit, a continental unit belonging to the Alpine Corsica (France), was reconstructed on the basis of U–Pb dating of zircon and allanite. Zircon was separated from a metagranitoid and an epidote-bearing metagabbro and analyzed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). Magm...

Subduction zones represent one of the most critical settings for fluid recycling as a consequence of dehydration of the subducting lithosphere. A better understanding of fluid flows within and out of the subducting slab is fundamental to unravel the role of fluids during burial. In this study, major and trace element geochemistry combined with oxyg...

Metamorphic olivine formed by the reaction of antigorite + brucite is widespread in serpentinites that crop out in glacier-polished outcrops at the Unterer Theodulglacier, Zermatt. Olivine overgrows a relic magnetite mesh texture formed during ocean floor serpentinization. Serpentinization is associated with rodingitisation of mafic dykes. Metamorp...

Understanding equilibrium relationships between minerals is a fundamental goal of metamorphic petrology, especially for the quantification of metamorphic conditions recorded by crustal rocks. Information on pressure (P) and temperature (T) can be derived from mineral compositions based on the a priori assumption that frozen‐in assemblages reflect c...

Hydrothermal dolomitization is an important diagenetic process that occurs in tectonic environments worldwide and forms conventional reservoirs associated with ore deposits and hydrocarbon accumulation, while forming efficient reservoirs for carbon sequestration. However, the current state of knowledge about the availability and reaction rate of Mg...

Epidote/allanite–fluorapatite coronae around monazite and xenotime are investigated in Permian pegmatites deformed under greenschist-facies conditions during Alpine tectonometamorphism in the Austroalpine basement, Eastern Alps. The aim was to evaluate the replacement reactions involved in the formation of a corona microstructure, its age and relat...

Subduction zones represent one of the most critical settings for fluid recycling as a consequence of dehydration of the subducting lithosphere. A better understanding of fluid flows within and out of the subducting slab is fundamental to unravel the role of fluids during burial. In this study, major and trace element geochemistry combined with oxyg...

The process of meteorological lightning-induced modification of coherent volcanic rocks is examined by geochemical, textural, and experimental analysis of fulgurites from South Sister volcano, Oregon Cascades, USA. Lightning's effects on volcanic target rocks was simulated with an arc-welding device in order to reproduce the geochemical and textura...

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...

Quantitative compositional mapping is a key technique for imaging solids and, therefore, for trying to understand compositional zoning systematics in a broad range of geological materials. Compositional mapping requires an adapted analytical method for efficient data collection, a post-processing calibration stage to obtain elemental concentration...

To provide a better picture of the active geodynamics along the Variscan suture zones during the late collisional stage (particularly regarding the evolution of the orogenic system towards HT conditions), we focused here on vaugnerites, which consist of mafic ultra-potassic magmatic rocks, intrusive into the granite-gneiss sequences of the Variscan...

Garnet is one of the most robust and ubiquitous minerals that record element zoning during crustal metamorphism. In addition to major elements, zoning in trace elements can provide a wealth of information to document the changing conditions of garnet growth and modification. However, mapping trace elements at low concentrations, over large areas an...

Garnet is a nominally anhydrous mineral that can incorporate several hundreds of ppm H2O in the form of OH groups, where H+ substitutes for cations in the garnet structure. To understand the effect of such small amounts of H2O on the physical and chemical properties of garnet, it is essential to determine where and how the OH groups are incorporate...

Oxygen isotope geochemistry is a powerful tool for investigating rocks that interacted with fluids, to assess fluid sources and quantify the conditions of fluid–rock interaction. We present an integrated modelling approach and the computer program PTLoop that combine thermodynamic and oxygen isotope fractionation modelling for multi-rock open syste...

A long-lived hydrothermal system at the Heyuan fault, South China, has led to the development of a giant quartz reef, now partially exhumed along its length for more than 40 km. Systematic analyses and focused microstructural studies have been undertaken to unravel a complex formation history of repeated fracturing, hydrothermal fluid flow and seal...

The concept of mineral assemblages is fundamental to the study of rocks, and this article portrays the evolution of thought and methods over the past 100 years. In metamorphic rocks, the locally coexisting minerals often reflect near-equilibrium states that were established at conditions of elevated pressure (P) and temperature (T). Most minerals a...

Oxygen isotope geochemistry is a powerful tool for investigating rocks that interacted with fluids, to assess fluid sources and quantify the conditions of fluid-rock interaction. We present an integrated modelling approach and the computer program PTLOOP that combine thermodynamic and oxygen isotope fractionation modelling for multi-rock open syste...

The Neogene evolution of the European Alps was characterized by the exhumation of crystalline basement, the so-called external crystalline massifs. Their exhumation presumably controlled the evolution of relief, distribution of drainage networks, and generation of sediment in the Central Alps. However, due to the absence of suitable proxies, the ti...

The Nevado-Filábride metamorphic complex (Betic Cordillera, Spain) exhibits a succession of Paleozoic and Mesozoic metasediments, orthogneisses and metabasites. The complex has been divided into three tectono-metamorphic units, from bottom to top: the Ragua, Calar-Alto and Bédar-Macael units. The petrochronological evolution of the complex is not w...

The Neogene evolution of the European Alps was characterized by the exhumation of crystalline basement, the so-called external crystalline massifs. Their exhumation presumably controlled the evolution of relief, distribution of drainage networks and generation of sediment in the Central Alps. However, due to the absence of suitable proxies, the tim...

The inherited localization model for shear zone development suggests that ductile deformation in the middle and lower continental crust is localized on mechanical anisotropies, like fractures, referred to as shear zone brittle precursors. In the Neves area (Western Tauern Window, Eastern Alps), although the structural control of these brittle precu...

Compositional mapping has greatly impacted mineralogical and petrological studies over the past half-century with increasing use of the electron probe micro-analyser. Many technical and analytical developments have benefited from the synergies of physicists and geologists and they have greatly contributed to the success of this analytical technique...

The astonishing progress of personal computer technology in the past 30 years as well as the availability of thermodynamic data and modeling programs have revolutionized our ability to investigate and quantify metamorphic processes. Equilibrium thermodynamics has played a central role in this revolution, providing simultaneously a physico-chemical...

Linking the timing of allanite growth to metamorphic conditions in metapelites is particularly challenging because of the large variety of allanite textures and chemical compositions. This study focuses on five garnet–biotite metapelites retrogressed to different extents, from the internal domain of the Longmen Shan (eastern Tibet) from which few p...

Eclogites are commonly seen as markers of subduction and thus their presence in Proterozoic and Archean orogenic provinces is crucial information for determining the initiation of modern plate tectonic. The Belomorian province hosts some of the oldest known eclogite-facies rocks. Here we present new garnet Lu–Hf geochronology that constrains the pr...

Sediment accumulation can occur in response to a change in either tectonic or climatic driving forces. Here, we explore these controls on the deposition of the Lima Conglomerate, Peru. We use a combination of quantitative methods to explore the age of sediment accumulation, the provenance of the material and the paleo‐erosion rates recorded by thes...

The investigation of ultrahigh temperature (UHT) metamorphic rocks, and their corresponding (pressure)-temperature-time (P-T-t) history is critical to distinguish between arc- or collision-related metamorphism. This is a very challenging task if mineral assemblages are highly retrogressed and isotopic systems are disturbed. Garnet-free granulites l...

The South Tien Shan (STS) belt results from the last collision event in the western Central Asian Orogenic Belt (CAOB). Understanding its formation is of prime importance in the general framework of the CAOB. The Atbashi Range preserves high‐pressure rocks along the South Tien Shan suture but still, its global metamorphic evolution remains poorly c...

Abstract EGU PICO session

The Earth crust is classically divided into (1) an upper crust characterized by brittle deformation, localized along frictional faults and (2) a mid-to lower crust with a viscous behavior, resulting in the development of ductile shear zones. This simplistic view is now challenged by many field observations, rock physics experiments and seismology,...