Mobilisation of rare earth elements in shear zones: Insights from the Tabouchent granodioritic pluton (Jebilet massif, Variscan Belt, Morocco)
| Autor: | Michel Corsini, Amal El Arbaoui, Alicja Lacinska, Kathryn Goodenough, Rachid Zayane, Abderrahim Essaifi |
|---|---|
| Přispěvatelé: | Université Cadi Ayyad [Marrakech] (UCA), British Geological Survey [Keyworth], British Geological Survey (BGS), Géoazur (GEOAZUR 7329), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Sud]), British Geological Survey [Edinburgh] |
| Rok vydání: | 2021 |
| Předmět: |
fluid flow
020209 energy Pluton Metamorphic rock Geochemistry 02 engineering and technology engineering.material 010502 geochemistry & geophysics Feldspar 01 natural sciences Variscan Geochemistry and Petrology 0202 electrical engineering electronic engineering information engineering Rare earth elements [SDU.STU.AG]Sciences of the Universe [physics]/Earth Sciences/Applied geology 0105 earth and related environmental sciences geography geography.geographical_feature_category Geology Massif Morocco Leucogranite 13. Climate action visual_art Monazite metal zonation visual_art.visual_art_medium engineering shear zones Economic Geology Shear zone Biotite [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy |
| Zdroj: | Ore Geology Reviews Ore Geology Reviews, In press, ⟨10.1016/j.oregeorev.2021.103996⟩ Ore Geology Reviews, Elsevier, In press, ⟨10.1016/j.oregeorev.2021.103996⟩ |
| ISSN: | 0169-1368 |
| Popis: | In the Jebilet massif (Variscan belt, Morocco), two peraluminous granodioritic plutons (the Eastern and Central Jebilet plutons) are spatially associated with a regional shear zone. The Central Jebilet pluton includes the Tabouchent, Bramram and Bamega intrusions, which represent variably eroded portions of an arcuate apical part of the pluton. The intrusions are composed of biotite ± cordierite-bearing granodiorite that is crosscut by tourmaline-bearing leucogranite, which is greisenized in the Bramram cupola. Fluorine, Sn-W (Au) mineralization is present in the pluton while Cu-Au and Pb-Zn-Ag-Au mineralizations are present in the contact metamorphic aureole around the intrusion. Deformation is more homogeneous in the Bramram and Bamega than in the Tabouchent granodioritic intrusion where deformation is very heterogeneous and concentrated within conjugate subvertical meter-scale ductile shear zones that crosscut the intrusion. In the shear zones the breakdown of feldspar and biotite resulted in the transformation of the granodiorite to phyllonites composed of quartz + muscovite ± chlorite. 40Ar/39Ar dating on white mica allowed us to date the regional shearing event to 305.9 ± 0.9 Ma. Fluid-rock interaction in the shear zones resulted in mobilization of rare earth elements (REE) and other major and trace elements. Na and Ca are typically leached from the shear zones while K and volatiles are gained. REE mobilisation was decoupled from that of the major elements and was accompanied by fractionation between light and heavy REE. It was mainly controlled by the alteration of magmatic accessory REE-bearing phases, predominantly monazite, followed by the reprecipitation of syntectonic monazite, xenotime, Th + Ca ± REE phosphate, Ce oxide and REE fluorocarbonates. Other typical changes in the shear zones are enrichments in Sn, W, As and Sb. The mineralogical and chemical changes recorded in the shear zones that crosscut the granodiorite are similar to those associated with the greisenization that affected the Bramram leucogranite. They indicate that the shear zones provide pathways for rising acidic magmatic fluids exsolved from S-type leucogranites. |
| Databáze: | OpenAIRE |
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