Montomoli C. -A multidisciplinary approach to the Crystalline Massifs of Western Alps: a cross-border geological link- Bando "Grant for Internationalization - GFI" - 2022
ProgettoState of the art
The External Crystalline Massifs (ECM) in Western Alps are fragments of the Variscan Belt well preserved within the Mediterranean area. The ECM recorded similar evolution and are composed of a high-to-medium grade metamorphic basement intruded by Permo-Carboniferous granoitoids. ECM have been strongly deformed during the Variscan orogeny and, together with their variably detached post-Variscan sedimentary cover, have been involved in the later Alpine tectonics, but only with localized and low-grade metamorphic overprint. Due to long-term structural geology constraints and recent tectonics and morphoclimatic conditions, ECMs show peculiar geodiversity and valuable geoheritage. We will focus on the Argentera-Mercantour Massif (AM), the southernmost ECM in the belt, at the boundary between Italy and France, where the components of both research units have a long working experience. The AM is constituted by two migmatite-bearing metamorphic complexes (Gesso-Stura-Vésubie and Tinée) (Compagnoni et al., 2010) separated by a Variscan ductile transpressive shear zone (Simonetti et al., 2018). Ferrando et al. (2008) recognized a polyphase Variscan metamorphic evolution starting from HP metamorphic conditions down to LT–LP amphibolite-facies imprint. An Alpine greenschist facies overprint has been related to the development of a system of shear zones affecting the whole AM (Sanchez et al., 2011). The complex shear zone network developed during Variscan and Alpine cycles covers a crucial role also for mining. Indeed, AM is one of the most promising European districts regarding probable “Critical Raw Materials” (CRMs) occurrences but still poorly explored and understood. Besides the area is well known for the occurrences of several hydrothermal mineralized veins, historically exploited for base metals (Cevales, 1961; Martina, 1967; Omenetto and Brigo., 1974), and for accessory Sc, V, Ni, and Co-bearing minerals within fluorite, and carbonate gangue, the relationships with mineralization and the complex structural architecture is still poorly understood. In this framework, the AM represents an invaluable archive of the geological history from Paleozoic to recent times, including the assembly and demise of Pangea and the latest glaciation phases in the Quaternary. The wide cultural heritage represented by a diversity of international known rock units, geological structures and landforms, testifies a very long history and gives the opportunity to identify and describe representative geosites for geo-tourism resources. The latter activities are crucial since the study area is within two National Parks (Parco Naturale Alpi Marittime, Parc National du Mercantour). Research design and objectives: The main goal of this study is to better define the stratigraphic and tectonic-metamorphic evolution of the AM and reconstruct the geological events also leading to the mobilization of metal-bearing fluids within the Variscan basement during Variscan and Alpine orogenic cycles. The CRMs occurrence within polymetallic hydrothermal vein systems hosted in the two different complexes and ductile, brittle-ductile shear zones and faults will also be investigated. In addition, we aim to define, according to international standards, candidate outcrops as suitable geosites for geoeducational activities addressed both to geological and-non geological audience.
In line with this purpose, the project will focus on eight specific tasks:
Task1. Refining the study of the control of structural inheritance of the Variscan architecture on the subsequent Alpine sedimentary cycle.
Task 2. Increasing the knowledge of the Variscan and post-Variscan tectono-metamorphic and magmatic evolution of the Massif, also by comparison between the Gesso-Stura-Vésubie and Tinée terranes.
Task 3. Understanding the structural relations among ductile and brittle -ductile shear zones and fault systems developed during the different orogenic cycles and their relations with the sedimentary Alpine covers.
Task 4. Definition of the geological and structural parameters controlling the hydrothermal fluids circulation and precipitation activity.
Task 5. Study of the hydrothermal veins’mineralogy, petrology, and geochemistry with major attention to CRMs deportment within gangue phases and accessory minerals associated with the main ore minerals.
Task 6: Definition of genetical parameters (pH, Salinity, T) governing the fluid precipitation and timing of mineral precipitation of the ore minerals and tectonic activity by analyzing suitable minerals and hosted fluid inclusions.
Task 7: Relevant steps in the stratigraphic, structural, metamorphic evolution of the AM and its most recent geomorphological history.
Task 8: Knowledge transfer and sharing with master’s and PhD students, from both Universities, through a “Field-based" summer school.
The main applied methods will be:
-Geological-structural mapping and collection of oriented samples.
-Petrographic and microstructural analyses of collected samples using optical and SEM-EDS microscopy and CIP (Computer Integrated Polarization Microscopy) to constrain the mineral assemblages (magmatic, metamorphic and hydrothermal) and their relations with the deformation mechanisms.
-Definition of P-T-d-t-X conditions of the collected samples through Electron Microprobe analyses, including high-resolution X-Ray chemical mapping, micro Raman spectroscopy, geothermobarometry and pseudosection modeling, , high quality state-of-art LA-ICP-MS petrochronology, geochemistry (trace elements, stable isotopes) and fluid inclusion study.
-Selection of geoheritage areas for further remote sensing and field based analyses of the geodiversity, targeted to geosite identification, selection, description and assessment Scientific outputs, grade of novelty, importance of the project, and dissemination
The project promotes an interdisciplinary approach to the study of tectono-metamorphic and stratigraphic evolution of AM, also related to primary raw materials, contributing to the personal and professional growth of the researchers and students involved, who will have the opportunity to acquire transversal skills in their academic/ professional careers. The project will benefit of collaboration with the Université Savoie Mont Blanc partner of the UNITA Montium. This joint project will favor interchanges between stakeholders, promoting the development of a multicultural research environment. Hence, the current proposal represents a unique and valuable opportunity to promote internationalization between the UNITA's partners. Dissemination of the research activities will be promoted by using international peer-review journals and international conferences. Seminars, workshops, and summer school between UNITA's Institutions will be organized to promote mobility between students/researchers and enhance internationalization.
The main expected outcomes are:
1) Modern multidisciplinary study on the stratigraphic, tectonic and petrologic evolution of the AM
2) New mineralogical, petrological and geochemical characterization of hydrothermal mineralization
3) Geochemistry, quantification, and deportment of CRMs within accessory minerals or gangue minerals. Definition of the genetical and age constrains
4) Redefining main ore minerals and definition of their economic potential gangue phases aimed to define their economic potential
5) Geosite identification, selection, description and assessment
References
Cevales G., 1961. Ind.Min., 12, (11), 677-684.
Compagnoni et al., 2010. J. Virtual Expl 36, 4
Ferrando et al. 2008. Eur J Mineral 20, 777–790
Martina E. 1967.Boll.Soc.Geol.It., 86, 797-807
Sanchez et al., 2011. Lithos 125, 521–536
Simonetti et al. 2018. Int. J. Earth Sci 107, 2163–2189
Omenetto & Brigo, 1974. Mem.Soc.Geol.It., 13/1, 339-362
• Cronoprogramma delle attività (2000 caratteri) *
The project will cover only 1 year, during which we will try to achieve preliminary results on some Working Packages (WPs).
• WP1: Bibliographical research regarding the study area.
• WP2: Field activity. The Field activity will be planned in both the Italian and French parts of the AM in collaboration with international partners. Field activities will consist of: i) geological structural mapping and structural characterization of the high strain zones, ductile to brittle ones, developed during the different orogenic cycles and their reciprocal relations; ii) detailed geological mapping of key area for the understanding of the evolution of the AM basement ; iii) study of the progressive deformation and definition of the different vein systems respect to the main tectonic phases and hydrothermal events; iii) collection of oriented samples for microstructural and petrological analyses and mineralized specimens;
• WP3: sample preparation for microstructural, petrographic, and fluid inclusions analyses (powders, polished blocks, thin sections, doubly polished sections).
• WP4: Wet chemical bulk geochemical ICP/MS-AES analyses and XRD analyses.
• WP5: in situ SEM-EDS and EMPA analyses and LA-ICP-MS datings.
• WP6: selection of suitable outcrops for geosites
• WP7: organization of a field-based summer school addressed to both master’s and Ph.D. students selected from both Universities
The data acquired will be elaborated on and discussed on light of the main research objectives for dissemination.
The External Crystalline Massifs (ECM) in Western Alps are fragments of the Variscan Belt well preserved within the Mediterranean area. The ECM recorded similar evolution and are composed of a high-to-medium grade metamorphic basement intruded by Permo-Carboniferous granoitoids. ECM have been strongly deformed during the Variscan orogeny and, together with their variably detached post-Variscan sedimentary cover, have been involved in the later Alpine tectonics, but only with localized and low-grade metamorphic overprint. Due to long-term structural geology constraints and recent tectonics and morphoclimatic conditions, ECMs show peculiar geodiversity and valuable geoheritage. We will focus on the Argentera-Mercantour Massif (AM), the southernmost ECM in the belt, at the boundary between Italy and France, where the components of both research units have a long working experience. The AM is constituted by two migmatite-bearing metamorphic complexes (Gesso-Stura-Vésubie and Tinée) (Compagnoni et al., 2010) separated by a Variscan ductile transpressive shear zone (Simonetti et al., 2018). Ferrando et al. (2008) recognized a polyphase Variscan metamorphic evolution starting from HP metamorphic conditions down to LT–LP amphibolite-facies imprint. An Alpine greenschist facies overprint has been related to the development of a system of shear zones affecting the whole AM (Sanchez et al., 2011). The complex shear zone network developed during Variscan and Alpine cycles covers a crucial role also for mining. Indeed, AM is one of the most promising European districts regarding probable “Critical Raw Materials” (CRMs) occurrences but still poorly explored and understood. Besides the area is well known for the occurrences of several hydrothermal mineralized veins, historically exploited for base metals (Cevales, 1961; Martina, 1967; Omenetto and Brigo., 1974), and for accessory Sc, V, Ni, and Co-bearing minerals within fluorite, and carbonate gangue, the relationships with mineralization and the complex structural architecture is still poorly understood. In this framework, the AM represents an invaluable archive of the geological history from Paleozoic to recent times, including the assembly and demise of Pangea and the latest glaciation phases in the Quaternary. The wide cultural heritage represented by a diversity of international known rock units, geological structures and landforms, testifies a very long history and gives the opportunity to identify and describe representative geosites for geo-tourism resources. The latter activities are crucial since the study area is within two National Parks (Parco Naturale Alpi Marittime, Parc National du Mercantour). Research design and objectives: The main goal of this study is to better define the stratigraphic and tectonic-metamorphic evolution of the AM and reconstruct the geological events also leading to the mobilization of metal-bearing fluids within the Variscan basement during Variscan and Alpine orogenic cycles. The CRMs occurrence within polymetallic hydrothermal vein systems hosted in the two different complexes and ductile, brittle-ductile shear zones and faults will also be investigated. In addition, we aim to define, according to international standards, candidate outcrops as suitable geosites for geoeducational activities addressed both to geological and-non geological audience.
In line with this purpose, the project will focus on eight specific tasks:
Task1. Refining the study of the control of structural inheritance of the Variscan architecture on the subsequent Alpine sedimentary cycle.
Task 2. Increasing the knowledge of the Variscan and post-Variscan tectono-metamorphic and magmatic evolution of the Massif, also by comparison between the Gesso-Stura-Vésubie and Tinée terranes.
Task 3. Understanding the structural relations among ductile and brittle -ductile shear zones and fault systems developed during the different orogenic cycles and their relations with the sedimentary Alpine covers.
Task 4. Definition of the geological and structural parameters controlling the hydrothermal fluids circulation and precipitation activity.
Task 5. Study of the hydrothermal veins’mineralogy, petrology, and geochemistry with major attention to CRMs deportment within gangue phases and accessory minerals associated with the main ore minerals.
Task 6: Definition of genetical parameters (pH, Salinity, T) governing the fluid precipitation and timing of mineral precipitation of the ore minerals and tectonic activity by analyzing suitable minerals and hosted fluid inclusions.
Task 7: Relevant steps in the stratigraphic, structural, metamorphic evolution of the AM and its most recent geomorphological history.
Task 8: Knowledge transfer and sharing with master’s and PhD students, from both Universities, through a “Field-based" summer school.
The main applied methods will be:
-Geological-structural mapping and collection of oriented samples.
-Petrographic and microstructural analyses of collected samples using optical and SEM-EDS microscopy and CIP (Computer Integrated Polarization Microscopy) to constrain the mineral assemblages (magmatic, metamorphic and hydrothermal) and their relations with the deformation mechanisms.
-Definition of P-T-d-t-X conditions of the collected samples through Electron Microprobe analyses, including high-resolution X-Ray chemical mapping, micro Raman spectroscopy, geothermobarometry and pseudosection modeling, , high quality state-of-art LA-ICP-MS petrochronology, geochemistry (trace elements, stable isotopes) and fluid inclusion study.
-Selection of geoheritage areas for further remote sensing and field based analyses of the geodiversity, targeted to geosite identification, selection, description and assessment Scientific outputs, grade of novelty, importance of the project, and dissemination
The project promotes an interdisciplinary approach to the study of tectono-metamorphic and stratigraphic evolution of AM, also related to primary raw materials, contributing to the personal and professional growth of the researchers and students involved, who will have the opportunity to acquire transversal skills in their academic/ professional careers. The project will benefit of collaboration with the Université Savoie Mont Blanc partner of the UNITA Montium. This joint project will favor interchanges between stakeholders, promoting the development of a multicultural research environment. Hence, the current proposal represents a unique and valuable opportunity to promote internationalization between the UNITA's partners. Dissemination of the research activities will be promoted by using international peer-review journals and international conferences. Seminars, workshops, and summer school between UNITA's Institutions will be organized to promote mobility between students/researchers and enhance internationalization.
The main expected outcomes are:
1) Modern multidisciplinary study on the stratigraphic, tectonic and petrologic evolution of the AM
2) New mineralogical, petrological and geochemical characterization of hydrothermal mineralization
3) Geochemistry, quantification, and deportment of CRMs within accessory minerals or gangue minerals. Definition of the genetical and age constrains
4) Redefining main ore minerals and definition of their economic potential gangue phases aimed to define their economic potential
5) Geosite identification, selection, description and assessment
References
Cevales G., 1961. Ind.Min., 12, (11), 677-684.
Compagnoni et al., 2010. J. Virtual Expl 36, 4
Ferrando et al. 2008. Eur J Mineral 20, 777–790
Martina E. 1967.Boll.Soc.Geol.It., 86, 797-807
Sanchez et al., 2011. Lithos 125, 521–536
Simonetti et al. 2018. Int. J. Earth Sci 107, 2163–2189
Omenetto & Brigo, 1974. Mem.Soc.Geol.It., 13/1, 339-362
• Cronoprogramma delle attività (2000 caratteri) *
The project will cover only 1 year, during which we will try to achieve preliminary results on some Working Packages (WPs).
• WP1: Bibliographical research regarding the study area.
• WP2: Field activity. The Field activity will be planned in both the Italian and French parts of the AM in collaboration with international partners. Field activities will consist of: i) geological structural mapping and structural characterization of the high strain zones, ductile to brittle ones, developed during the different orogenic cycles and their reciprocal relations; ii) detailed geological mapping of key area for the understanding of the evolution of the AM basement ; iii) study of the progressive deformation and definition of the different vein systems respect to the main tectonic phases and hydrothermal events; iii) collection of oriented samples for microstructural and petrological analyses and mineralized specimens;
• WP3: sample preparation for microstructural, petrographic, and fluid inclusions analyses (powders, polished blocks, thin sections, doubly polished sections).
• WP4: Wet chemical bulk geochemical ICP/MS-AES analyses and XRD analyses.
• WP5: in situ SEM-EDS and EMPA analyses and LA-ICP-MS datings.
• WP6: selection of suitable outcrops for geosites
• WP7: organization of a field-based summer school addressed to both master’s and Ph.D. students selected from both Universities
The data acquired will be elaborated on and discussed on light of the main research objectives for dissemination.