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Monazite behaviour in polycyclic rocks: a tool for better constraining the thermo-tectonic evolution of the Alpine belt

Applicant Manzotti Paola
Number 161202
Funding scheme Ambizione
Research institution Institut des sciences de la Terre Université de Lausanne
Institution of higher education University of Lausanne - LA
Main discipline Geochronology
Start/End 01.01.2016 - 31.12.2018
Approved amount 418'172.00
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All Disciplines (4)

Discipline
Geochronology
Other disciplines of Earth Sciences
Geochemistry
Geology

Keywords (3)

thermo-tectonic models; petrology; geochronology

Lay Summary (Italian)

Lead
Comportamento della monazite nelle rocce policicliche: uno strumento per meglio comprendere l'evoluzione termo-tettonica della catena alpina.
Lay summary

Lo scopo di questo progetto è quello di migliorare la conoscenza dei processi responsabili della formazione delle catene montuose, utilizzando un approccio quantitativo per determinare dei parametri chiave, come i tassi di riscaldamento/raffreddamento e di seppellimento ed esumazione delle rocce. Al fine di determinare questi parametri, sono necessarie età geocronologiche molto precise e solide. Tali età possono essere ottenute datando un minerale che è presente in piccole quantità in molte rocce: la monazite. Questo progetto vuole dunque studiare il comportamento della monazite nelle rocce policicliche provenienti dalle Alpi Occidentali.

Gli scopi principali del progetto comprendono:

  • Caratterizzare le relazioni tra la monazite e altri minerali in rocce che si sono formate in diversi condizioni di pressione e di temperatura;
  • Studiare gli scambi chimici tra la monazite e gli altri minerali maggiori che costituiscono la roccia studiata;
  • Stimare le traiettorie P-T (di pressione e temperatura) seguiti dai campioni di roccia, selezionati per lo studio del comportamento della monazite;
  • Datare i diversi domini di crescita della monazite , utilizzando diverse tecniche analitiche;
  • Correlare le età ottenute sui diversi domini di crescita della monazite a specifici stadi metamorfici per i quali saranno determinate le condizioni di P e T;
  • Derivare stime quantitative dei tassi di riscaldamento/raffreddamento e di seppellimento/esumazione delle rocce.

Gli scopi sopra descritti saranno perseguiti utilizzando un approccio multidisciplinare, che combina lo studio geologico di terreno con l’analisi dei minerali ad una scala microscopica e con la geocronologia.

L’importanza di questo progetto risiede nel fatto che la determinazione di parametri come i tassi di riscaldamento/raffreddamento o di seppellimento/esumazione delle rocce costituisce un vincolo chiave per i modelli numerici, che hanno come scopo la simulazione dell’evoluzione termo-meccanica delle catene montuose.

Direct link to Lay Summary Last update: 02.09.2015

Responsible applicant and co-applicants

Employees

Publications

Publication
Exhumation rates in the Gran Paradiso Massif (Western Alps) constrained by in situ U-Th-Pb dating of accessory phases (monazite, allanite and xenotime)
Manzotti Paola, Bosse Valérie, Pitra Pavel, Robyr Martin, Schiavi Federica, Ballèvre Michel (2018), Exhumation rates in the Gran Paradiso Massif (Western Alps) constrained by in situ U-Th-Pb dating of accessory phases (monazite, allanite and xenotime), in Contributions to Mineralogy and Petrology, 173(3), 24.
Pre-Alpine (Variscan) inheritance: a key for the location of the future Valaisan ocean (Western Alps)
BallevreMichel, ManzottiPaola, Dal PiazGiorgio Vittorio (2018), Pre-Alpine (Variscan) inheritance: a key for the location of the future Valaisan ocean (Western Alps), in Tectonics, 37, 786-817.
Tectonic history of the Dent Blanche. Field guide of the Swiss Tectonic Studies Group (Valpelline, August 2016)
Manzotti Paola, Ballévre Michel (2017), Tectonic history of the Dent Blanche. Field guide of the Swiss Tectonic Studies Group (Valpelline, August 2016), in Geological Field Trips, 9(1.2), 1-73.
Permian high temperature metamorphism in the Western Alps (NW Italy)
Kunz Barbara, Manzotti Paola, von Niederhäusern Brigitte, Engi Martin, Giuntoli Francesco, Lanari Pierre (2017), Permian high temperature metamorphism in the Western Alps (NW Italy), in International Journal of Earth Sciences, 203-229.
Continental gabbros in the Dent Blanche Tectonic System (Western Alps): from the pre-Alpine crustal structure of the Adriatic palaeo-margin to the geometry of an alleged subduction interface.
Paola Manzotti, Michel Ballèvre, Giorgio Vittorio Dal Piaz (2017), Continental gabbros in the Dent Blanche Tectonic System (Western Alps): from the pre-Alpine crustal structure of the Adriatic palaeo-margin to the geometry of an alleged subduction interface., in Journal of the Geological Society, London, 174, 541-556.
Permian magmatism and metamorphism in the Dent Blanche nappe: constraints from field observations and geochronology
Manzotti Paola, Rubatto Daniela, Zucali Michele, El Korh Afifé, Cenki-Tok Bénédicte, Ballèvre Michel, Engi Martin (2017), Permian magmatism and metamorphism in the Dent Blanche nappe: constraints from field observations and geochronology, in Swiss Journal of Geosciences, 111, 79-97.

Collaboration

Group / person Country
Types of collaboration
Isotope Geology/ Institute of Geological Sciences/University of Bern/ Dr. Daniela Rubatto Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Géosciences Rennes, Université de Rennes1, Prof. M. Ballèvre France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Équipe de Géochimie, Laboratoire Magmas et Volcans, Dr. F. Schiavi France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Géosciences Rennes, Université de Rennes1, Dr. G. Ruffet France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Géosciences Rennes, Université de Rennes1, Dr. P. Pitra France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Isotope Geology /Institute of Earth Sciences, Lausanne/ Dr. Florence Begue, Dr. Anne-Sophie Bouvier Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Isotope Geology/Institute of Earth Sciences, Lausanne/Dr. Alexey Ulianov Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Research Infrastructure
Stable isotopes / Institute of Earth Sciences, Lausanne / Dr. B. Putlitz Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Igneous and metamophic petrology/Institute of Earth Sciences, Lausanne/Prof. Baumgartner, Müntener Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Équipe de Géochimie, Laboratoire Magmas et Volcans, Dr. Valérie Bosse France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Metamorphic petrology/Institute of Earth Sciences, Lausanne / Dr. M. Robyr Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
16th Swiss Geoscience Meeting Poster Sodic amphibole and sodic clinopyroxene in the Dent Blanche (Western Alps): new constraints for an old question 30.11.2018 Bern, Switzerland Manzotti Paola;
EGU Talk given at a conference Timing of detachment and rates of exhumation constrained by in situ U-Th-Pb dating (monazite, allanite, xenotime): the Gran Paradiso case 07.04.2018 Vienna, Austria Manzotti Paola;
15th Swiss Geoscience Meeting Talk given at a conference Permian magmatism and metamorphism in the Dent Blanche nappe: constraints from field observations and geochronolog 17.11.2017 Davos, Switzerland Manzotti Paola;
13th Workshop on Alpine Geological Studies (EGU) Talk given at a conference Timing of detachment of continental slices from the downgoing slab in a subduction zone 07.09.2017 Zlatibor, Serbien Manzotti Paola;
13th Workshop on Alpine Geological Studies (EGU) Poster Permian high-temperature metamorphism in the Western Alps (NW Italy) 07.09.2017 Zlatibor, Serbien Manzotti Paola;
Goldschmidt Talk given at a conference Rate of detachment of continental slices from the downgoing slab in a subduction zone 13.08.2017 Paris, France Manzotti Paola;


Abstract

The aim of this project is to improve our understanding of the dynamics of processes leading to mountain belts, using a quantitative approach to constrain key parameters like heating/cooling rates, and burial/exhumation rates. For this, we need very precise and reliable age data, that can be obtained by dating a mineral present in small amounts in many rocks i.e. monazite. This project will explore the behaviour of monazite in polycyclic rocks from the Western Alps and utilize the robust age data in orogenic analysis.The project will include the following main steps:-Characterizing monazite phase relations in rocks formed over a wide range of P-T conditions, with particular focus on the monazite behaviour at high pressure conditions;-Studying the exchange of Rare Earth Elements (REE) between monazite (and other accessory REE-phases) and major silicates in high-pressure / medium-temperature rocks;-Determining the survival mechanisms of monazite through successive orogenic cycles;-Deriving P-T paths for specific samples, selected for monazite geochronology-Dating monazite growth domains by Th-Pb and U-Pb isotopy, using LA-ICP-MS in situ analysis and SIMS (for particularly small monazite domains);-Relating monazite ages (i.e. time, t) to specific metamorphic stages for which pressure (P) and temperature (T) conditions have been estimated, thus constraining specific parts of the PTt-paths;-Testing the reliability of ages when several generations of monazite occur in a single rock sample;-Deriving quantitative estimates of the heating/cooling rates, burial/exhumation rates, and of the rates of displacement along crustal-scale thrusts, by the integration of the monazite ages with all the other age data, and the P-T-t paths constructed in this study.The aims of this project will be achieved using a multidisciplinary approach that combines geological fieldwork, petrological and microstructural analysis, in situ geochronology, and REE-geochemistry.In a more general and wider context, determining these parameters is of major importance as they serve as key constraints for numerical models that aim to simulate the thermo-mechanical evolution of mountains belts.
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