Variscan U-Th-Pb age for stratabound Pb-Zn mineralization in the Bossòst dome (Pyrenean Axial Zone)

Cugerone, Alexandre; Roger, Françoise; Cenki, Bénédicte; Oliot, Émilien; Paquette, Jean‐Louis

doi:10.1016/j.oregeorev.2021.104503

Cited by 7 publications

(10 citation statements)

References 123 publications

(253 reference statements)

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“…A channel flow progressing from the French Central Massif to the Pyrenees would necessitate synchronous extension setting in the hinterlands and compressional regime in the forelands (Rey et al, 2010;Whitney et al 2013), but our results rather suggest coeval extension in both hinterlands and forelands between 325-310 Ma. Considering the presence of a Visean Serpukhovian magmatism and metamorphism in the PAZ and NPZ (Mezger and Gerdes 2016;Schnapperelle et al 2020;Cugerone et al 2021; this study), it seems likely that the lower crust of the Variscan Pyrenees was already in high-temperature conditions at 325-310 Ma and probably molten. Therefore, we propose that the whole lower crust of the PAZ, NPZ and Montagne Noire melted at ca.…”

Section: Tectonic Implicationsmentioning

confidence: 64%

“…The Pyrenean Axial Zone (PAZ) and the North Pyrenean Zone (NPZ) are separated by the EW-striking North Pyrenean Fault (NPF). These two zones consist of Proterozoic to Paleozoic sedimentary rocks deformed and metamorphosed between the middle Carboniferous and the early Permian (Mezger and Gerdes 2016;Denèle et al 2014;Aguilar et al 2013;Schnapperelle et al 2020;Vacherat et al 2017;Cochelin et al 2021;Cugerone et al 2021;Vielzeuf et al 2021). In both PAZ and NPZ, the Variscan orogeny is associated with a widespread Carboniferous to Permian magmatism (e.g.…”

Section: Geological Settingmentioning

confidence: 99%

“…Similarly, monazite and zircon ages of 340-320 Ma have been reported in migmatites from the southern French Central Massif (Faure et al 2014), in migmatites and granites of the PAZ (Mezger and Gerdes 2016;Lopez-Sanchez et al, 2019;Schnapperelle et al 2020) and migmatites of the NPZ (Lemirre 2016). However, the origin of this Visean/Serpukhovian magmatic and metamorphic event in the foreland is still debated (Roger et al 2015;Schnapperelle et al 2020;Cugerone et al 2021). Thermobarometric estimates on the Montagne Noire (MN) gneiss dome suggest that, between 330 and 320 Ma, the continental crust was slightly overthickened with a partially molten lower-middle crust, at a depth between 30 and 40 km (Trap et al 2017;Whitney et al 2020).…”

Section: Middle Carboniferous Crustal Partial Melting and Magmatism E...mentioning

confidence: 99%

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Flow of the partially molten crust in the Variscan foreland revealed by U–Th–Pb dating of metamorphism, magmatism and deformation (Agly Massif, Eastern Pyrenees)

Vanardois

Trap

Roger

et al. 2022

Int J Earth Sci (Geol Rundsch)

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In this contribution, we investigate the spatial and temporal evolution of mid-crustal flow in the Agly massif (North Pyrenean Zone) that represents the southern foreland of the Variscan orogenic plateau.In the Agly massif, the middle crust is represented by an Ediacarian-Devonian series of metasedimentary rocks that recorded high-grade metamorphism synchronously with crustal thinning (D2) and dextral wrenching (D3) during Carboniferous. D2 crustal thinning formed a penetrative S2 flat-lying foliation and localized C2 extensional shear zones with a top-to-the-North kinematics. D2 planar fabrics are deformed by a D3 dextral transpression localized into a two-kilometers wide highstrain zone. We performed LA-ICPMS U-Th-Pb dating on zircon and monazite from small magmatic bodies and from metamorphic rocks showing strain features relative to D2 and/or D3. Our results, compiled with published data, argue that the middle crust of the Agly massif reached high-temperature and suprasolidus conditions at ca. 325-320 Ma and was partially molten until ca. 300 Ma. They also indicate that the D2 thinning and top-to-the north shearing was active from ca. 325 to 290 Ma. D2 extension and D3 transpression were synchronous from ca. 308 to 290 Ma. Making a comparison with the Pyrenean Axial Zone, the Montagne Noire and the French Central massif, we propose a two-step tectonic model for the mid-crustal flow with a horizontal flow towards South in both the orogenic plateau and the southern forelands between ca. 325 and 310 Ma and locally reoriented into an E-W longitudinal flow between 310 and 300 Ma in high-strain dextral strike-slip shearing domains.

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Section: Tectonic Implicationsmentioning

confidence: 64%

Section: Geological Settingmentioning

confidence: 99%

Section: Middle Carboniferous Crustal Partial Melting and Magmatism E...mentioning

confidence: 99%

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Flow of the partially molten crust in the Variscan foreland revealed by U–Th–Pb dating of metamorphism, magmatism and deformation (Agly Massif, Eastern Pyrenees)

Vanardois

Trap

Roger

et al. 2022

Int J Earth Sci (Geol Rundsch)

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“…Type (i) sphalerite is part of the epigenetic stratabound stage and is synchronous to the main Variscan magmatic event (Cugerone et al 2021b; Fig. 1C).…”

Section: )mentioning

confidence: 99%

Plastic deformation and trace element mobility in sphalerite

Cugerone,

Oliot,

Munoz

et al. 2024

American Mineralogist

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Sphalerite (ZnS) is a sulfide found in a large variety of ore deposits and is frequently hosted in metamorphic terranes that have undergone deformation and related recrystallization.However, deformation mechanisms of sphalerite are still poorly understood because recrystallization evidence is barely visible under the optical microscope and may reflect complex and frequently multistage mechanisms. Furthermore, sphalerite may host up to a few thousands ppm of critical metals such as gallium (Ga), germanium (Ge), and indium (In).Metamorphic conditions and dynamic recrystallization may have induced local or total redistribution of these elements. Modern techniques such as electron backscattered diffraction analyses (EBSD) and laser induced breakdown spectroscopy (LIBS) applied on sphalerite allow to detect grain boundaries, crystal-plastic deformation and internal chemical diffusion, which classically reflect active deformation mechanisms. In this study, a microstructural and in-situ chemical comparison between four sphalerite types (type i, ii, iii, iv) is made for the first time. The four sphalerite types present different deformation imprints although they are hosted in a similar geological setting: the Pyrenean Axial Zone and the Montagne Noire Variscan massifs (France). Based on EBSD and LIBS mapping, we describe two regional sphalerite growth stages composed of dark red crystals with polygonal shape (type i; Bentaillou-Liat deposit) and light to dark-brown euhedral crystals (type iii; Saint Salvy deposit). New investigation at microscale on sphalerite grains from the Saint-Salvy deposit shows late Cu-Ge-Ga enrichment not only in specific sector zonings, but also in grain boundaries, growing crystal edges and in low angle misorientation or twin boundaries.Following a deformation event that probably occurred during the Pyrenean-Alpine orogeny, these two sphalerite mineralizations have both endured plastic deformation in a dislocation creep regime and dynamically recovered by subgrain rotation (SGR) mechanism. Two mechanisms of Cu-Ga-Ge spatial redistribution are observed and are key processes for the

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“…They are located in the same litho-structural context in Permo-Triassic phyllitic quartzite of the External Briançonnais domain of the Internal Alps. In the absence of ages or mineralizing conditions (P, T, speciation), metallogenic models are still debated because of the stratiform or vein-like type mineralizations that could either result from sedimentary or orogenic processes [3][4][5][6][7][8]13], as for other worldwide Pb-Zn(-Ag-Cu) deposits in several mountain belts (e.g., Pyrenees, Mount Isa region, and North China craton) mainly considered initially as sedimentary but revealed in fact to be orogen-driven [14][15][16][17][18]. This study proposes for the first time a multitechnique investigation on these two deposits, coupling field observations, microstructure and mineral paragenesis identification, and thermobarometry and geochronology.…”

Section: Introductionmentioning

confidence: 99%

A New Alpine Metallogenic Model for the Pb-Ag Orogenic Deposits of Macôt-la Plagne and Peisey-Nancroix (Western Alps, France)

et al. 2022

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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 discriminate between the metallogenic models of the two deposits, an integrative methodology combining field, microstructural, mineralogical, thermobarometrical, and geochronological data was here applied for establishing detailed Pressure–Temperature–Time–Deformation (P-T-t-d) mineralization conditions. Both deposits are located in Permo-Triassic quartzite of the External Briançonnais domain along the Internal Briançonnais Front (Internal Western Alps). The ore mainly occurs as veins and disseminated textures containing galena, pyrite, and variable content of tetrahedrite–tennantite and chalcopyrite. Quartz porphyroclasts and sulfide microstructures indicate a dynamic recrystallization of the quartzite during the main fluid mineralization episode. Chlorites and K-white micas (phengite) chemical analysis and thermodynamic modeling from compositional maps indicate an onset of the mineralization at 280 °C, with a main precipitation stage at 315 ± 35 °C and 6.25 ± 0.75 kbar. In situ U-Pb dating on monazite, cogenetic with sulfides, gives ages around 35 Ma for both deposits. The integrative dataset converges for a cogenetic MP-PN Alpine Pb-Ag mineralization during deformation in relation to the thrusting of the “Nappe des Gypses” and the Internal Briançonnais at the metamorphic peak.

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Variscan U-Th-Pb age for stratabound Pb-Zn mineralization in the Bossòst dome (Pyrenean Axial Zone)

Cited by 7 publications

References 123 publications

Flow of the partially molten crust in the Variscan foreland revealed by U–Th–Pb dating of metamorphism, magmatism and deformation (Agly Massif, Eastern Pyrenees)

Flow of the partially molten crust in the Variscan foreland revealed by U–Th–Pb dating of metamorphism, magmatism and deformation (Agly Massif, Eastern Pyrenees)

Plastic deformation and trace element mobility in sphalerite

A New Alpine Metallogenic Model for the Pb-Ag Orogenic Deposits of Macôt-la Plagne and Peisey-Nancroix (Western Alps, France)

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