Mobility of trace elements and oxygen in zircon during metamorphism: Consequences for geochemical tracing

Martin, Laure; Duchêne, Stéphanie; Deloule, Étienne; Vanderhaeghe, Olivier

doi:10.1016/j.epsl.2007.11.029

Cited by 126 publications

(65 citation statements)

References 47 publications

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“…Migmatite crystallization has been dated at ca. 17 Ma [Keay et al, 2001;Martin et al, 2006Martin et al, , 2008; therefore, the temporal framework of core complex formation, doming, and partial melting on Naxos is well documented.…”

Section: Geological Contextmentioning

confidence: 99%

“…[47] Structural relationships, microstructural characteristics, and previous geochronology [e.g., Keay et al, 2001;Martin et al, 2006Martin et al, , 2008 all suggest that deformation in the Naxos migmatites took place in the presence of melt that was coeval with Oligocene-Miocene extensional tectonics, and the upwelling and emplacement of the Naxos dome core. The correspondence of structural and magnetic data over scales ranging from the specimen to dome scale, in migmatites of variable composition, are interpreted to suggest that the apparent complexity of migmatites may mask a Figure 11.…”

Section: Bulk Viscoplastic Flow In Migmatitesmentioning

confidence: 99%

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Viscoplastic flow in migmatites deduced from fabric anisotropy: An example from the Naxos dome, Greece

et al. 2010

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[1] Many migmatites represent crystallized partially molten crust and therefore record the mechanisms and pathways of orogenic crustal flow. Field and microstructural methods may be insufficient to characterize the planar and linear elements of rock fabric in migmatites due to obscured flow fabrics or protracted deformation. In the Naxos dome (Greece), we test the anisotropy of magnetic susceptibility (AMS) as a tool for recovering mineral fabric symmetry and the kinematic axes of flow in migmatites. Measurements of 155 migmatite samples yield dominantly low values (<300 × 10 −6 [SI]) of bulk magnetic susceptibility (K m ) consistent with biotite being the dominant carrier of the AMS. Higher values of K m , thermomagnetic, hysteresis, and microstructural data, however, suggest a ferromagnetic contribution from magnetite in a subset of samples (N = 15). Using electron backscatter diffraction (EBSD) analysis, we establish the correspondence of the biotite subfabric with the AMS and structural fabric of the Naxos migmatites. EBSD data from biotite suggests that magnetic lineation in these dominantly paramagnetic migmatites arises from a zone axis orientation of biotite crystals organized about the direction of viscoplastic flow. Over a range of spatial scales, migmatitic foliation and magnetic foliation are well correlated. The magnetic lineation recovered by AMS displays a coherent organization despite the heterogeneous structure and composition of the Naxos migmatites. These data suggest that the apparent complexity of migmatites masks a simpler flow regime controlled by bulk viscoplastic flow. Furthermore, our study demonstrates the utility of the AMS method for studying the dynamics of partially molten orogenic crust.

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Section: Geological Contextmentioning

confidence: 99%

Section: Bulk Viscoplastic Flow In Migmatitesmentioning

confidence: 99%

Viscoplastic flow in migmatites deduced from fabric anisotropy: An example from the Naxos dome, Greece

et al. 2010

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“…The high LREE concentrations of this type of zircon were not attributed to the theoretical partition coefficients of LREE between zircon and melt (Thomas et al 2002;Hanchar and Westrenen 2007), instead they are considered to be the result of LREE-rich inclusions in zircon or dramatically different behavior of LREE in highly evolved magmatic systems (Bakker and Elburg 2006). Generally, zircon from highly evolved granitic rocks is commonly porous and may contain U, Th, Nb, and Tarich inclusions when the host rocks experienced mineralization or alteration (Thomas et al 2003;Tomaschek et al 2003;Geisler et al 2007;Martin et al 2008;Hay and Dempster 2009;Van Lichtervelde et al 2009). However, the time-resolved LA-ICPMS spectra and element distribution maps (Electronic Supplementary Material Fig.…”

Section: Distinct Ree Compositions Of Magmatic and Hydrothermal Zirconmentioning

confidence: 99%

Geochemistry of magmatic and hydrothermal zircon from the highly evolved Baerzhe alkaline granite: implications for Zr–REE–Nb mineralization

et al. 2013

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The Baerzhe alkaline granite pluton hosts one of the largest rare metal (Zr, rare earth elements, and Nb) deposits in Asia. It contains a geological resource of about 100 Mt at 1.84 % ZrO 2 , 0.30 % Ce 2 O 3 , and 0.26 % Nb 2 O 5 . Zirconium, rare earth elements (REE), and Nb are primarily hosted by zircon, yttroceberysite, fergusonite, ferrocolumbite, and pyrochlore. Three types of zircon can be identified in the deposit: magmatic, metamict, and hydrothermal. Primary magmatic zircon grains occur in the barren hypersolvus granite and are commonly prismatic, with oscillatory zones and abundant melt and mineral inclusions. The occurrence of aegirine and fluorite in the recrystallized melt inclusions hosted in the magmatic zircon indicates that the parental magma of the Baerzhe pluton is alkali-and F-rich. Metamict zircon grains occur in the mineralized subsolvus granite and are commonly prismatic and murky with cracks, pores, and mineral inclusions. They commonly show dissolution textures, indicating a magmatic origin with later metamictization due to deuteric hydrothermal alteration. Hydrothermal zircon grains occur in mineralized subsolvus granite and are dipyramidal with quartz inclusions, with murky CL images. They have 608 to 2,502 ppm light REE and 787 to 2,521 ppm Nb, much higher than magmatic zircon. The texture and composition of the three types of zircon indicate that they experienced remobilization and recrystallization during the transition from a magmatic to a hydrothermal system. Large amounts of Zr, REE, and Nb were enriched and precipitated during the transitional period to form the giant low-grade Baerzhe Zr-REE-Nb deposit.

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“…Large-scale isoclinal folds and other deformation structures formed during D1 were overprinted by top-to-north shearing of D2, starting at the onset of crustal thinning and post-orogenic extension in the early Miocene (Mercier et al, 1976;Ring et al, 2010;Urai et al, 1990). As a consequence of crustal thinning and extension of the Aegean domain, the rocks of Naxos were overprinted by regional-scale greenschist metamorphism at ∼ 25 Ma (M2 a ), and more localized high-temperature, lowpressure metamorphism (M2 b ) with thermal dome formation and partial anatexis at ∼ 16 Ma (Duchene et al, 2006;Keay et al, 2001;Martin et al, 2006Martin et al, , 2008. The metamorphic grade of M2 b decreases from a high-grade migmatitic core down to greenschist facies along its fringes (Jansen and Schuiling, 1976).…”

Section: Geological Settingmentioning

confidence: 99%

Multiphase boudinage: a case study of amphibolites in marble in the Naxos migmatite core

2018

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Abstract. In multiply deformed terrains multiphase boudinage is common, but identification and analysis of these is difficult. Here we present an analysis of multiphase boudinage and fold structures in deformed amphibolite layers in marble from the migmatitic centre of the Naxos metamorphic core complex. Overprinting between multiple boudinage generations is shown in exceptional 3-D outcrop. We identify five generations of boudinage, reflecting the transition from high-strain high-temperature ductile deformation to medium-to low-strain brittle boudins formed during cooling and exhumation. All boudin generations indicate E-W horizontal shortening and variable direction of bedding parallel extension, evolving from subvertical extension in the earliest boudins to subhorizontal N-S extension during exhumation. Two phases of E-W shortening can be inferred, the first associated with lower crustal synmigmatic convergent flow and the second associated with exhumation and N-S extension, possibly related to movement of the North Anatolian Fault.

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Mobility of trace elements and oxygen in zircon during metamorphism: Consequences for geochemical tracing

Cited by 126 publications

References 47 publications

Viscoplastic flow in migmatites deduced from fabric anisotropy: An example from the Naxos dome, Greece

Viscoplastic flow in migmatites deduced from fabric anisotropy: An example from the Naxos dome, Greece

Geochemistry of magmatic and hydrothermal zircon from the highly evolved Baerzhe alkaline granite: implications for Zr–REE–Nb mineralization

Multiphase boudinage: a case study of amphibolites in marble in the Naxos migmatite core

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