K-feldspar phenocrysts in microgranular magmatic enclaves: A cathodoluminescence and geochemical study of crystal growth as a marker of magma mingling dynamics

Słaby, Ewa; Götze, Jens; Wörner, Gerhard; Simon, Klaus; Wrzalik, R.; Śmigielski, Michał

doi:10.1016/j.lithos.2008.02.006

Cited by 79 publications

(54 citation statements)

References 43 publications

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“…9a-e). Slaby et al (2008) explain the different blue CL colours by variation in the defect density. The alkali-feldspar matrix crystals (type 2) also often grew Fig.…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 88%

“…The mainly greenish-blue to purple CL colours of these intergrown (cross-shaped) plagioclases (Fig. 9f) display twin lamellae, whereas the greenish-blue colour might indicate a higher defect density in these crystals (Slaby et al 2008). The pinkish CL colour, which is often seen in the core, points to the occurrence of Al 3?…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 95%

“…The pinkish CL colour, which is often seen in the core, points to the occurrence of Al 3? substitution (EMS data, Drachenfels 2004), or iron atoms that have acted as an activator (Götze et al 2000;Slaby et al 2002Slaby et al , 2008. The zoning is irregular and discordant.…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 98%

“…The alkali-feldspars also possess defect centres (healing and redistribution) similar to quartz minerals (see above; Figs. 8, 9;Slaby et al 2008).…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 99%

“…Different blue CL colours in alkali-feldspar may point to chemical variation during crystallization (Drachenfels pers. comm., printed with permission) or varying defect densities (Slaby et al 2008). d Corroded and resorbed (arrow) and altered plagioclase crystals with lath-shaped grain mantle (Drachenfels pers.…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 99%

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Multi-stage emplacement of the Götemar Pluton, SE Sweden: new evidence inferred from field observations and microfabric analysis, including cathodoluminescence microscopy

Friese

Vollbrecht

Tanner

et al. 2011

Int J Earth Sci (Geol Rundsch)

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The emplacement of the Mesoproterozoic Götemar Pluton into Paleoproterozoic granitoid host rocks of the Transscandinavian Igneous Belt is re-examined by microfabric analysis, including cathodoluminescence microscopy. Field data on the pluton-host rock system are used to strengthen the model. The Götemar Pluton, situated on the Baltic Shield of SE Sweden, is a horizontally zoned tabular structure that was constructed by the intrusion of successive pulses of magma with different crystal/melt ratios, at an estimated crustal depth of 4-8 km. Initial pluton formation involved magma ascent along a vertical dike, which was arrested at a mechanical discontinuity within the granitoid host rocks; this led to the formation of an initial sill. Subsequent sill stacking and their constant inflation resulted in deformation and reheating of existing magma bodies, which also raised the pluton roof. This multi-stage emplacement scenario is indicated by complex dike relationships and the occurrence of several generations of quartz (Si-metasomatism). The sills were charged by different domains of a heterogeneous magma chamber with varying crystal/melt ratios. Ascent or emplacement of magma with a high crystal/melt ratio is indicated by syn-magmatic deformation of phenocrysts. Complex crystallization fabrics (e.g. oscillatory growth zoning caused by high crystal defect density, overgrowth and replacement features, resorbed and corroded crystal cores, rapakivi structure) are mostly related to processes within the main chamber, that is repeated magma mixing or water influx.

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“…9a-e). Slaby et al (2008) explain the different blue CL colours by variation in the defect density. The alkali-feldspar matrix crystals (type 2) also often grew Fig.…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 88%

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 95%

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 98%

“…The alkali-feldspars also possess defect centres (healing and redistribution) similar to quartz minerals (see above; Figs. 8, 9;Slaby et al 2008).…”

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 99%

Section: Characteristics Of Alkali-feldspar and Plagioclasementioning

confidence: 99%

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Multi-stage emplacement of the Götemar Pluton, SE Sweden: new evidence inferred from field observations and microfabric analysis, including cathodoluminescence microscopy

Friese

Vollbrecht

Tanner

et al. 2011

Int J Earth Sci (Geol Rundsch)

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Multistage magma emplacement and progressive strain accumulation in the shallow‐level Krkonoše‐Jizera plutonic complex, Bohemian Massif

et al. 2013

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[1] Field relationships combined with new U-Pb zircon geochronology suggest that the shallow-level Krkonoše-Jizera plutonic complex, northern Bohemian Massif, was assembled successively from bottom to top, starting with emplacement of the separately evolved S-type Tanvald granite (317.3 ± 2.1 Ma), followed by at least two voluminous batches of the I-type porphyritic Liberec (319.5 ± 2.3 Ma) and Jizera (320.1 ± 3.0 Ma and 319.3 ± 3.7 Ma) granites. The intrusive sequence was completed by uppermost, minor intrusions of the equigranular Harrachov (315.0 ± 2.7 Ma) and Krkonoše granites. The I-type granites exhibit an unusually complex pattern of superposed feldspar phenocryst and magnetic fabrics as revealed from the anisotropy of magnetic susceptibility (AMS). The outer Liberec granite preserves margin-parallel foliations and lineations, interpreted to record emplacement-related strain captured by cooling from the pluton floor and walls. In contrast, the inner Jizera, Harrachov, and Krkonoše granites were overprinted by synmagmatic strain resulting from dextral movements along regional strike-slip faults cutting the opposite ends of the plutonic complex. Late-stage felsic dikes in the Liberec and Jizera granites reorient from horizontal to vertical (lineation-perpendicular) attitude in response to changing the least principal stress direction, whereas mafic schlieren do not do so, representing only randomly oriented small-scale thermal-mechanical instabilities in the phenocryst framework. In general, this case example challenges the common approach of inferring pluton-wide magma flow from interpolated foliation, lineation, and schlieren patterns. More likely, magmatic fabrics in large plutons record complex temporal succession of superposed strains resulting from diverse processes at multiple scales.

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Magma Mixing: History and Dynamics of an Eruption Trigger

Morgavi

Arienzo

Montagna

et al. 2017

Advances in Volcanology

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The most violent and catastrophic volcanic eruptions on Earth have been triggered by the refilling of a felsic volcanic magma chamber by a hotter more mafic magma. Examples include Vesuvius 79 AD, Krakatau 1883, Pinatubo 1991, and Eyjafjallajökull 2010. Since the first hypothesis, plenty of evidence of magma mixing processes, in all tectonic environments, has accumulated in the literature allowing this natural process to be defined as fundamental petrological processes playing a role in triggering volcanic eruptions, and in the generation of the compositional variability of igneous rocks. Combined with petrographic, mineral chemistry and geochemical investigations, isotopic analyses on volcanic rocks have revealed compositional variations at different length scales pointing to a complex interplay of fractional crystallization, mixing/mingling and crustal contamination during the evolution of several magmatic feeding systems. But to fully understand the dynamics of mixing and mingling

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K-feldspar phenocrysts in microgranular magmatic enclaves: A cathodoluminescence and geochemical study of crystal growth as a marker of magma mingling dynamics

Cited by 79 publications

References 43 publications

Multi-stage emplacement of the Götemar Pluton, SE Sweden: new evidence inferred from field observations and microfabric analysis, including cathodoluminescence microscopy

Multi-stage emplacement of the Götemar Pluton, SE Sweden: new evidence inferred from field observations and microfabric analysis, including cathodoluminescence microscopy

Multistage magma emplacement and progressive strain accumulation in the shallow‐level Krkonoše‐Jizera plutonic complex, Bohemian Massif

Magma Mixing: History and Dynamics of an Eruption Trigger

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