Metamorphic history of garnet-rich gneiss at Ktiš in the Lhenice shear zone, Moldanubian Zone of the southern Bohemian Massif, inferred from inclusions and compositional zoning of garnet

Kobayashi, Tomoyuki; Hirajima, Tsuyoshi; Kawakami, Tetsuo; Svojtka, Martin

doi:10.1016/j.lithos.2010.11.003

Cited by 16 publications

(4 citation statements)

References 78 publications

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“…The peak temperatures estimated by Faryad (2009) are slightly lower compared with temperatures estimated for the eclogites in this study, but the preservation of prograde zoning in garnet at 900 °C also suggests a relatively short duration of heating (Faryad, 2009). Prograde garnet zoning has also been found in high-P granulite from the Gföhl Unit (e.g., Carswell and O'Brien, 1993) and in garnet-rich gneiss at Ktiš from the Lhenice shear zone of the southern Bohemian Massif (Kobayashi et al, 2011). The garnet-rich gneiss also underwent high-T metamorphism of approximately 800-900 °C.…”

Section: Residence Time At the Peak Metamorphic Stagecontrasting

confidence: 53%

Multiple origins of UHP eclogites in a garnet peridotite block (Nové Dvory, Czech Republic) and short duration of heating

ITAMI

Nakamura

Yasumoto

et al. 2022

Journal of Mineralogical and Petrological Sciences

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The origins of eclogite associated with garnet peridotite in continent-continent collision belts are still debated. We performed petrological studies of eclogites collected from a garnet peridotite block from Nové Dvory in the Gföhl Unit of the Moldanubian Zone in the Variscan orogenic belt, Czech Republic. The eclogite was divided into three types: one kyanite (Ky)-bearing and two Ky-free types. Garnet and omphacite in the Ky-bearing eclogite have lower Fe contents than those in the Ky-free eclogite. Furthermore, the Ky-free eclogite was divided into two types on the basis of Ca content in garnet: Ca-rich (X grs > 0.32) and Ca-poor (X grs < 0.32) types, except for Ca-poor rim compositions. Application of conventional geothermobarometers to the Ky-bearing type and the Ky-free type with Ca-rich garnet yielded similar pressure-temperature (P-T ) conditions (3.2-4.8 GPa and 920-1160 °C) to those of previous studies, whereas the Ky-free type with Ca-poor garnet yielded slightly lower P-T conditions (3.1-3.4 GPa and 950-990 °C) than the other two types. The observed chemical variation of garnet is probably due to the difference in origins, whereby, according to our new results and previous findings, the Kybearing eclogite was derived from plagioclase-bearing crustal gabbro, whereas the Ky-free eclogite with Ca-rich garnet was derived from a crystal cumulate possibly in the mantle wedge. In the Ky-free eclogite samples with Ca-poor garnet, chemical compositions of garnet and omphacite are different from those in the other Ky-free samples, and those samples with Ca-poor garnet would have a different origin from the others. One of the Kyfree type with Ca-poor garnet retains garnet grains with chemical zonings probably created during the prograde history, although the eclogite underwent the extremely high temperature (~1000 °C) metamorphism. Calculated diffusion distances in garnet reach 0.5 mm during 2 million years, even if we adopted a low value of diffusion coefficient data. Thus, the residence time of the eclogite at the peak meatamorphic conditions would have been shorter than at least 2 million years. The subsequent decompression and cooling after the peak metamorphism were also probably very fast to avoid the chemical homogenization of garnet.

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Section: Residence Time At the Peak Metamorphic Stagecontrasting

confidence: 53%

Multiple origins of UHP eclogites in a garnet peridotite block (Nové Dvory, Czech Republic) and short duration of heating

ITAMI

Nakamura

Yasumoto

et al. 2022

Journal of Mineralogical and Petrological Sciences

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“…Therefore it is possible that the garnet only experienced a limited diffusion modification during retrograde metamorphism. In fact, many studies demonstrated that garnets in HT (N 800°C and even up to 900°C) granulites have partially or completely preserved their prograde growth zoning, characterized by decreasing grossular and spessartine contents, accompanied by an increasing pyrope content, during late cooling and exhumation (e.g., Anczkiewicz et al, 2007;Kobayashi et al, 2011;Nahodilova et al, 2014).…”

Section: Petrology and Mineral Chemistrymentioning

confidence: 99%

Long-lived high-temperature granulite-facies metamorphism in the Eastern Himalayan orogen, south Tibet

Zhang

Xiang

Dong

et al. 2015

Lithos

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“…Fluid inclusions with CO 2 are commonly reported from high grade metamorphic rocks in the world (e.g., Kobayashi et al, 2011) and also from mantle rocks (e.g., Yamamoto et al, 2007). H 2 O-NaCl-CH 4 fluid are reported as the peak metamorphic stage fluid of the chlorite zone of the Sanbagawa belt (Nishimura et al, 2008) Nevertheless, detailed discussion on the evolutional changes of carbon and other volatile species is beyond the purpose of this paper.…”

Section: Volatile Component Of Fluid Inclusionsmentioning

confidence: 99%

Geochemical features and relative B–Li–Cl compositions of deep-origin fluids trapped in high-pressure metamorphic rocks

Yoshida

Hirajima

Ohsawa

et al. 2015

Lithos

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The relationships between the relative B-Li-Cl compositions of deep fluids and their entrapment depth were investigated by means of geochemical studies of fluid inclusions in foliation-parallel quartz veins using the crush-leach method and conventional petrology. Investigated samples were collected from the Sanbagawa metamorphic belt, SW Japan, covering the metamorphic grade from the pumpellyite-actinolite facies (300 ºC/ 0.5 GPa) to the quartz-eclogite facies (550-650 ºC/ 1.5-2.5 GPa). We took a special care on the relationship between arrangements of fluid inclusions and grain fabric of their host quartz to evaluate the entrapment timing of fluid inclusions. Our results show that quartz veins can be classified into three groups based on their fabrics: polygonal type (P-type), deformed-interlobate-grain type (DI-type) and pervasively-deformed-domain type (DD-type). P-type fabrics in the studied samples indicate textural development under the conditions of very low differential stress with relatively high temperature and free from subsequent brittle deformation, thus, the corresponding fluid inclusions should have been trapped during the peak metamorphic stage or in the early stage of exhumation. On the other hand, fabrics of DI-and DD-type, such as largely 2 deformed lamellae and undulatory extinction, are thought to be formed under high differential stress and low temperatures (<400 ºC) during the later stage of exhumation. Fluid inclusions in DI-/DDtype veins are thought to be trapped in association with the later-stage deformation event and corresponding fluid infiltration. P-type veins tend to contain relatively high saline aqueous fluids (5-10 mass% NaCleq) and their compositions are mainly Na-Cl dominated. DI-/DD-type veins contain dilute aqueous fluid (<5 mass% NaCleq) and some of them are characterized by the dominance of HCO 3 in anions. The relative B-Li-Cl compositions of the studied fluids are characterized by high (B+Li)/Cl ratio, which is characteristics of the Arima-type hydrothermal fluids, thought to be directly derived from the subducting-slab at the present fore-arc region of the Japanese island chain. The Li/B ratios of the studied fluids show a large variation from a low value of 0.02 in the pumpellyiteactinolite facies/ DD-type sample to a high value of 1.99 in the eclogite facies/ P-type sample. These results suggest that high-saline and B-Li-enriched fluids are supplied from subducting slabs to the hanging wall mantle wedge in the subduction zone.

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Metamorphic history of garnet-rich gneiss at Ktiš in the Lhenice shear zone, Moldanubian Zone of the southern Bohemian Massif, inferred from inclusions and compositional zoning of garnet

Cited by 16 publications

References 78 publications

Multiple origins of UHP eclogites in a garnet peridotite block (Nové Dvory, Czech Republic) and short duration of heating

Multiple origins of UHP eclogites in a garnet peridotite block (Nové Dvory, Czech Republic) and short duration of heating

Long-lived high-temperature granulite-facies metamorphism in the Eastern Himalayan orogen, south Tibet

Geochemical features and relative B–Li–Cl compositions of deep-origin fluids trapped in high-pressure metamorphic rocks

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