Article
Geology
Jonas Vanardois, Francoise Roger, Pierre Trap, Philippe Goncalves, Pierre Lanari, Jean-Louis Paquette, Didier Marquer, Florence Cagnard, Benjamin Le Bayon, Jeremie Melleton, Fabrice Barou
Summary: This study investigates mafic eclogite relics in the Aiguilles-Rouges massif of the Western Alps and suggests that they are remnants of continental lower crust exhumed and juxtaposed with lower-grade migmatites in crust-scale vertical transpressive shear zones.
JOURNAL OF METAMORPHIC GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Jonas Vanardois, Pierre Trap, Francoise Roger, Jeremie Melleton, Didier Marquer, Jean-Louis Paquette, Philippe Goncalves, Florence Cagnard, Benjamin Le Bayon
Summary: This study investigates the dynamics of a crustal-scale shear zone, the mechanisms of pluton emplacement, and the magma sources in the Aiguilles-Rouges and Mont-Blanc massifs in the East Variscan Shear Zone.
JOURNAL OF STRUCTURAL GEOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Kevin Freville, Pierre Trap, Jonas Vanardois, Jeremie Melleton, Michel Faure, Olivier Bruguier, Marc Poujol, Philippe Lach
Summary: This study provides a reappraisal of the Variscan tectono-metamorphic history of the Pelvoux Massif, proposing a new understanding of the flow pattern and kinematics of the Variscan crust and the Eastern Variscan Shear Zone. The results suggest a sinistral transpression and NW-SE shortening event, with the onset of crustal partial melting around 650 degrees C during the late Visean. The findings also indicate strain partitioning and horizontal crustal flow, as well as the southeastward motion of the partially molten crust.
BSGF-EARTH SCIENCES BULLETIN
(2022)
Article
Geochemistry & Geophysics
A. Mercier, P. H. Leloup, G. Courrioux, S. Caritg, S. Lopez, P. Grandjean, S. Passot, A. Kalifi
Summary: Although the Helvetic nappes of the Western Alps have been extensively studied, there is still controversy surrounding their style, amount, and timing of deformation during the Alpine orogeny. In this study, using new field data, microtectonics, and 3D geological modeling, we investigate the tectonic evolution of the Aiguilles Rouges and Mont-Blanc massifs and their relationship with the nappe stacking. Our findings reveal significant thrusting of the Helvetic Mesozoic sedimentary cover above the Aiguilles Rouges basement towards the WNW. We propose that the subalpine ranges are mostly klippes above the Helvetic Basal thrust (HBT), with estimated shortening of 13 to 32 km.
Article
Geosciences, Multidisciplinary
Veronique Gardien, Jean-Emmanuel Martelat, Philippe-Herve Leloup, Gweltaz Maheo, Benoit Bevillard, Pascal Allemand, Patrick Monie, Jean-Louis Paquette, Anne-Sabine Grosjean, Michel Faure, Cyril Chelle-Michou, Clementine Fellah
Summary: A leucogranite sill in the footwall of the extensional Pilat shear zone was emplaced and sheared between 301.8 +/- 3.1 and 303.0 +/- 1.6 Ma. The existence of a relief south of the shear zone and the filling of the St. Etienne Basin confirm the extensional phase. The rapid exhumation of the Velay dome was likely due to localized sub crustal lithospheric mantle dripping.
Article
Geology
Luc de Hoym de Marien, Pavel Pitra, Marc Poujol, Nathan Cogne, Florence Cagnard, Benjamin Le Bayon
Summary: Two eclogites from the French Massif Central underwent prograde evolution, heating, partial melting, and subsequent exhumation, revealing a complex tectonic history involving an Ordovician rifting event, Devonian subduction, and Carboniferous exhumation. The previously proposed Silurian age for the subduction has been definitively rejected. The petrochronological record of zircon shows a complex pattern of metamorphic ages, while apatite and rutile yield a well-defined age of about 350 Ma. Fractures filled with analcite, thomsonite, plagioclase, and biotite indicate late interaction with alkaline fluids at relatively low temperatures.
JOURNAL OF METAMORPHIC GEOLOGY
(2023)
Article
Geochemistry & Geophysics
Mariana Werle, Gary Stevens, Jean-Francois Moyen, Oscar Laurent, Chris Harris, Cristiano C. Lana, Philip E. Janney
Summary: The processes of crustal growth by addition of new mantle-derived material to the crust and recycling of crustal components remain poorly understood in collisional orogens due to the introduction of crustal components during subduction events. A study of lamprophyric-granitic composite dykes from the Variscan Aigoual granite in the French Massif Central reveals co-magmatic lamprophyres and granites with similar characteristics. The isotopic signatures of both rock types indicate a dual crust/mantle origin, suggesting partial melting of an enriched mantle metasomatised by subducted sediments.
Article
Geology
Florent Cheval-Garabedian, Eric Marcoux, Hugues Raimbourg, Michel Faure
Summary: By studying the La Lucette deposit in the French Armorican Massif, the relationship between Sb-Au-W and the metallogenic processes of the deposit were revealed. The deposit is characterized by four ore deposition stages with different mineral assemblages. The formation of the deposit is closely related to the temperature and mixing processes of the fluids, and does not require significant burial or involvement of late magmatic events.
ORE GEOLOGY REVIEWS
(2023)
Article
Geochemistry & Geophysics
Stacy E. E. Phillips, Tom W. W. Argles, Clare J. J. Warren, Nigel B. W. Harris, Barbara E. E. Kunz
Summary: The morphology, cathodoluminescence response and trace element composition of kyanite in migmatite from Eastern Bhutan were studied to distinguish between sub-solidus kyanite and kyanite crystallized directly from partial melt. The findings have significant implications for the interpretation of kyanite-bearing migmatites as representing early stages of melting during Himalayan evolution.
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
(2023)
Article
Geochemistry & Geophysics
Jean-Baptiste Jacob, Emilie Janots, Stephane Guillot, Daniela Rubatto, Kevin Freville, Jeremie Melleton, Michel Faure
Summary: The Oisans-Pelvoux massif in the Western Alps records high temperature metamorphism and intense migmatization during the Variscan orogeny. New findings of high pressure mafic granulites provide insights into the early evolution of the unit, with relics of Mn-rich garnet cores revealing prograde stages and HP assemblages indicating peak-P conditions and subsequent decompression to HT granulite-facies conditions.
Article
Geography, Physical
Nezha Lazreq, Peter Koenigshof, Abderrahim Essaifi, Ali Bouari, Abdelhak Outigua
Summary: The Sarhlef Formation in the Moroccan Meseta region has been reevaluated to Late Devonian in age based on new biostratigraphic data, which is more compatible with the radiometric data of intrusive magmatic rocks in the region. This provides new insights into the geological evolution and stratigraphy of the area.
PALAEOGEOGRAPHY PALAEOCLIMATOLOGY PALAEOECOLOGY
(2021)
Article
Geology
Jean-Baptiste Jacob, Stephane Guillot, Daniela Rubatto, Emilie Janots, Jeremie Melleton, Michel Faure
Summary: The study confirms the age of Variscan high-pressure metamorphism in the Palaeozoic basement of the western Alps, with ages of 456 ± 4 Ma and 448 ± 6 Ma obtained from eclogites. The peak pressure stage in the retrogressed eclogites was estimated to be >1.4 GPa at 690-740 degrees C, followed by decompression. Metamorphic zircon rims yield U-Pb dates scattering between 340 and 310 Ma, representing late stages of melt crystallization. The development of a mylonitic S2 foliation correlates with retrogression in the amphibolite facies during the mid-late Carboniferous, indicating exhumation of eclogites mixed with mid-crustal felsic lithologies.
JOURNAL OF METAMORPHIC GEOLOGY
(2021)
Article
Geochemistry & Geophysics
Lois Monnier, Jeremie Melleton, Olivier Vanderhaeghe, Stefano Salvi, Philippe Lach, Olivier Bruguier, Anissa Benmammar, Laurent Bailly, Didier Beziat, Eric Gloaguen
Summary: Monazite and rutile in the French Massif Central were dated using U-Pb isotopic systematics, revealing evidence of multiple mineralizing fluid percolation events over 50 Ma. These findings, when compared to other major W provinces, suggest an original geodynamic-metallogenic scenario in the context of the Variscan belt evolution.
Article
Geochemistry & Geophysics
Cristina Accotto, Antonio Azor, David Martinez Poyatos, Antonio Pedrera, Francisco Gonzalez Lodeiro
Summary: The Ossa-Morena Zone is a Gondwana-related terrane composed mainly of Cambrian rocks. U-Pb dating of zircon grains from 15 samples revealed the absence of a significant Stenian-early Tonian population in the Cambrian Ossa-Morena rocks, in contrast to the results from middle Ordovician-Lower Devonian rocks in the same area. This suggests a change in the paleogeographic/paleotectonic evolution of the Ossa-Morena Zone during the late Ediacaran-early Ordovician period, possibly involving an eastward displacement and a reorganization of drainage systems.
Article
Geochemistry & Geophysics
Matthieu Harlaux, Christian Marignac, Patrick A. Carr, Julien Mercadier, Christophe Ballouard, Yujin Jegal, Kalin Kouzmanov, Yann Foucaud, Alfredo Camacho, Jean Cauzid, Michel Cuney
Summary: This study unveils the origin of Sn-W mineralization in the southeastern French Massif Central and its relation to regional metamorphism, partial melting, and granite emplacement. The results indicate that the mineralization occurred during a regional low-pressure-medium-temperature metamorphism at around 320-315 Ma, along with magmatic-hydrothermal activity; further research is needed to confirm the temporal and spatial decoupling of W and Sn mineralization. The emplacement of granitic dikes occurred during a regional high-temperature metamorphism, possibly linked to lower crustal metamorphism.
MINERALIUM DEPOSITA
(2023)
Article
Geology
Evangelos Moulas, Stefan M. Schmalholz, Yury Podladchikov, Lucie Tajcmanova, Dimitrios Kostopoulos, Lukas Baumgartner
JOURNAL OF METAMORPHIC GEOLOGY
(2019)
Article
Geochemistry & Geophysics
J. Pape, K. Mezger, A. -S. Bouvier, L. P. Baumgartner
GEOCHIMICA ET COSMOCHIMICA ACTA
(2019)
Article
Geography
Nicolas Buchs, Jean-Luc Epard
Article
Geochemistry & Geophysics
D. G. Cisneros-Lazaro, J. A. Miller, L. P. Baumgartner
CONTRIBUTIONS TO MINERALOGY AND PETROLOGY
(2019)
Article
Geochemistry & Geophysics
Anne-Sophie Bouvier, Melina Manzini, Estelle F. Rose-Koga, Alexander R. L. Nichols, Lukas P. Baumgartner
EARTH AND PLANETARY SCIENCE LETTERS
(2019)
Article
Geosciences, Multidisciplinary
Romain Lafay, Lukas P. Baumgartner, Benita Putlitz, Guillaume Siron
Article
Geochemistry & Geophysics
Melina Manzini, Anne-Sophie Bouvier, Lukas P. Baumgartner, Estelle F. Rose-Koga, Pierre Schiano, Nobumichi Shimizu
Article
Geochemistry & Geophysics
Katharina Marger, Matthieu Harlaux, Andrea Rielli, Lukas P. Baumgartner, Andrea Dini, Barbara L. Dutrow, Anne-Sophie Bouvier
GEOSTANDARDS AND GEOANALYTICAL RESEARCH
(2020)
Article
Geochemistry & Geophysics
Florian Humair, Arthur Bauville, Jean-Luc Epard, Stefan M. Schmalholz
Article
Geochemistry & Geophysics
Benjamin Malvoisin, Chang Zhang, Othmar Muntener, Lukas P. Baumgartner, Peter B. Kelemen
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2020)
Article
Geosciences, Multidisciplinary
Adrien Pantet, Jean-Luc Epard, Henri Masson
SWISS JOURNAL OF GEOSCIENCES
(2020)
Article
Geochemistry & Geophysics
Guillaume Siron, Robert Bodner, Lukas Baumgartner, Benita Putlitz, Torsten Vennemann
Summary: The metamorphic rocks from the Torres del Paine contact aureole in Patagonia, Chile, exhibit evidence of infiltration by igneous fluids, as indicated by changes in hydrogen isotope ratios and relatively low fluid flux. Oxygen isotope ratios did not show systematic changes, suggesting that oxygen loss or exchange was not significant. The presence of minor fluid infiltration was supported by chlorine content in biotite crystals, with high concentrations near the intrusion.
AMERICAN MINERALOGIST
(2021)
Article
Geochemistry & Geophysics
Cindy Luisier, Lukas P. Baumgartner, Anne-Sophie Bouvier, Benita Putlitz
Summary: This study investigates the interplay between metamorphism and fluid events in a metasomatic whiteschist and its granite protolith in the Monte Rosa nappe, Western Alps, using in situ oxygen isotope compositions of white mica and quartz. The results reveal complete recrystallization of the whiteschist protolith during intense fluid-rock interaction, with multiple events of fluid infiltration and expulsion identified. The findings also provide insights into the metamorphic evolution of the whiteschist, from late Permian intrusion to Alpine subduction. The isotopic compositions of the whiteschist and the metagranites show significant differences, indicating different fluid-rock interactions and metamorphic processes.
AMERICAN MINERALOGIST
(2022)
Article
Geosciences, Multidisciplinary
Adrien Pantet, Jean-Luc Epard, Henri Masson, Claudia Baumgartner-Mora, Peter Oliver Baumgartner, Lukas Baumgartner
Summary: The Schistes Lustres represent a large and complex unit in the Alpine belt, composed mainly of calcschists of Late Cretaceous age. The origin of the Schistes Lustres has been debated, and this study provides new evidence suggesting that they consist of sediments deposited on either oceanic crust or a hyper-extended continental margin. Structural and stratigraphic observations, as well as Raman graphite thermometry data, support this interpretation.
SWISS JOURNAL OF GEOSCIENCES
(2023)
Article
Geochemistry & Geophysics
Huichuan Liu, Alan R. Hastie, Chiara Maria Petrone
Summary: This study conducted isotope analyses on two ocean island basalt (OIB)-associated enriched mafic intrusions in the Yunnan-Burma region, and found that these rocks may have originated from the subduction recycling of marine sediments and altered oceanic crust.
Article
Geochemistry & Geophysics
L. Notini, M. Scambelluri, A. Tommasi, A. Zanetti, F. Ferri, A. Rodriguez-Vargas, E. Rampone
Summary: This study provides important petrologic information on the mantle wedge above an active subduction zone in Southern Colombia. The researchers analyzed a unique suite of rock samples and found evidence of hydration, metasomatism, and partial melting in the mantle wedge. They also observed variations in lithotypes, textures, and mineral abundance, indicating different interactions with melts and fluids. This study sheds light on the complex petrological processes occurring in the mantle wedge and contributes to our understanding of subduction zone dynamics.
Article
Geochemistry & Geophysics
Sourav Bhattacharjee, Aniket Chakrabarty, Roger H. Mitchell, Suresh Chandra Patel, Evgeniy N. Kozlov, Ekaterina N. Fomina, Monojit Dey, Supratim Pal
Summary: The Hogenakkal complex in India consists of silicate-rich and silicate-poor carbonatites and clinopyroxenites. The formation of carbonatite is influenced by silicate minerals. The carbohydrothermal mineralization in the carbonatites is induced by magma-derived fluids and interactions with the surrounding rocks.
Article
Geochemistry & Geophysics
Jia-Min Wang, Kyle Patrick Larson, Jin-Jiang Zhang, Liang Zhao, Fu-Yuan Wu
Summary: The role of collisional belts in the global carbon budget is controversial. This study reveals a previously unrecognized carbon source in the collisional orogen of the Himalayas, where metamorphism of carbonate-bearing rocks in the hanging wall resulted in significant CO2 degassing.
Article
Geochemistry & Geophysics
Joseph Martial Akame, Elson Paiva Oliveira, Vinciane Debaille, Marc Poujol, Bernhard Schulz, Dieudonnee Bisso, Fabien Humbert, Serge Parfait Koah Na Lebogo, Philmont Zo'o Zame
Summary: Archean granitoids play key roles in the crustal evolution and can provide important insights into early geologic processes.
Article
Geochemistry & Geophysics
Xiguang Huang, Jun He, Jingxin Zhao, Jingzhao Dou, Weiyong Li, Aimin Hu, Ge Liu, Yiru Ji, Fukun Chen, Shuangqing Li
Summary: This study investigates the zircon ages and whole-rock geochemical data of Late Paleozoic magmatic rocks in the Western Yunnan Tethyan belt to identify the origin and mechanism of mantle melting. The results suggest that these magmatic rocks may originate from different mantle domains that were metasomatized by slab-derived fluids and sediment-derived melts.