Tachylyte in Cenozoic basaltic lavas from the Czech Republic and Iceland: contrasting compositional trends

Ulrych, Jaromír; Krmíček, Lukáš; Teschner, Claudia; Řanda, Z.; Skála, Roman; Jonášová, Šárka; Fediuk, Ferry; Adamović, Jiří; Pokorný, Richard

doi:10.1007/s00710-016-0483-x

Cited by 3 publications

(2 citation statements)

References 43 publications

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“…Amphibole samples show a trend towards EM1-type mantle which can be partly shifted towards HIMU. Plotted for comparison are the fields for the Cenozoic volcanics of the Bohemian Massif (Haase and Renno, 2008;Lustrino and Wilson, 2007;Ulrych et al, 2008Ulrych et al, , 2013Ulrych et al, , 2016Ulrych et al, , 2017; for Urach and Hegau (Alibert et al, 1983;Hegner et al, 1995;Wilson et al, 1995); for the Rhön area (Mayer et al, 2013amphibole-bearing lavas;Mayer et al, 2014amphibole samples); for the Loučná-Oberwiesenthal Volcanic Centre (LOVC; Ulrych et al, 2005clinopyroxene samples) and for the Massif Central/Vosges (Alibert et al, 1983) are plotted for comparison. BSE = Bulk Silicate Earth; CHUR = Chondritic Uniform Reservoir; DMM = Depleted MORB Mantle; EAR = European Asthenospheric Reservoir; HIMU = high μ ( 238 U/ 204 Pb); EM1 = Enriched Mantle 1; EM2 = Enriched Mantle 2 (Cebrià and Wilson, 1995;Granet et al, 1995;Hart, 1988;Zindler and Hart, 1986).…”

Section: Sr-nd Isotope Signature Of Amphibolesmentioning

confidence: 99%

Chemistry and Sr-Nd isotope signature of amphiboles of the magnesio-hastingsite–pargasite–kaersutite series in Cenozoic volcanic rocks: Insight into lithospheric mantle beneath the Bohemian Massif

Ulrych

Krmíček

Teschner

et al. 2018

Lithos

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Amphibole phenocrysts, xenocrysts and cumulate xenoliths from Cenozoic volcanic rocks of the Bohemian Massif (BM) belong to the magnesio-hastingsite-pargasite-kaersutite series. Their host rocks are mostly basaltic lavas, stocks, dykes and breccia pipe fills, less commonly also felsic rocks. Felsic rocks with amphibole cumulate xenoliths represent differentiated magmas which have undergone polybaric fractionation of the mafic minerals. The calculated p-T conditions suggest that almost all amphiboles crystallized in a relatively narrow temperature range (1020-1100°C) at depths of~20-45 km (0.7-1.2 GPa) during the magma ascent. These p-T estimates are compatible with the published experimental data on the stability of kaersutite. We therefore suggest the presence of a deep magma chamber situated close to the crust-mantle boundary where amphibole xenoliths to megacrysts could have formed. Nevertheless, crystallization of rare amphibole rims during the magma ascent was observed in a hornblendite cumulate in sodalite syenite from "Giegelberg". The lowest concentration of incompatible elements in the amphiboles was found in xenocrysts in alkaline basaltic rocks and mantle xenoliths and megacrysts, followed by phenocrysts/xenocrysts in lamprophyric rocks, xenocrysts of cumulates in felsic rocks, and phenocrysts in subvolcanic rocks. Amphibole compositional and Sr-Nd isotope characteristics resemble those of amphiboles from metasomatic clinopyroxene/amphibole veins in mantle peridotites. The initial 143 Nd/ 144 Nd and 87 Sr/ 86 Sr ratios of amphiboles (0.51266-0.51281 and 0.70328-0.70407, respectively) are similar to those of their whole rocks (0.51266-0.51288 and 0.70341-0.70462, respectively). Amphiboles of the magnesio-hastingsite-pargasite-kaersutite series of the BM are mostly chemically homogeneous, with no pronounced Mg-Fe fractionation and zoning. The amphiboles are characterized by relatively homogeneous εNd (i) = +1.4 to +3.8 values: only a single sample from the České Středohoří Volcanic Complex (CSVC) yielded a negative εNd (i) (−0.6). This testifies to locally elevated proportions of recycled Variscan crustal material during melting of mantle peridotites rich in clinopyroxene-amphibole veins. These veins were formed by metasomatic fluids enriched in High Field Strength Elements (HFSE) and are isotopically similar to Enriched Mantle1 (EM1)-type mantle. Amphibole host rocks occur in areas with a significant concentration of basaltic magmas in rift zones along lithospheric block boundaries of the BM. Lithospheric mantle beneath such zones was probably strongly influenced by metasomatic fluids during the formation of clinopyroxene-amphibole veins in mantle peridotite that facilitated the generation of basaltic magma with amphibole.

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Section: Sr-nd Isotope Signature Of Amphibolesmentioning

confidence: 99%

Chemistry and Sr-Nd isotope signature of amphiboles of the magnesio-hastingsite–pargasite–kaersutite series in Cenozoic volcanic rocks: Insight into lithospheric mantle beneath the Bohemian Massif

Ulrych

Krmíček

Teschner

et al. 2018

Lithos

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“…Relatively uniform distribution of interstitial tachylyte is indicative of rapid cooling during the dyke emplacement without dramatic changing of P-T-X conditions (e.g. Kuboušková et al 2016;Ulrych et al 2017). Petrographic thin sections made from marginal pseudo-hieroglyphs revealed that they do not texturally or compositionally deviate from the host basaltic rock (Fig.…”

Section: Pseudo-hieroglyphs-definition Morphology Petrography and Omentioning

confidence: 99%

Basaltic Dyke with Specific Volcanogenic Structures and Its Geomorphic Evolution: Unique Geoheritage of the Faroe Islands (North Atlantic Ocean)

et al. 2018

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Volcanic landforms resulting from Cenozoic volcanism represent the most peculiar features of global geodiversity and provide eminent narratives for geoeducation. Among them, however, relict volcanic forms and site-specific landforms in remote areas have received less attention. In this paper, we provide the first description of unique volcanogenic features (hereinafter referred to as pseudo-hieroglyphs) developed on a summit rock wall at the Sandfelli ridge near the village of Gjógv in the N Eysturoy Island (Faroe Islands). The geomorphic evolution of the ridge and rock wall during the Quaternary is described and detailed petrographic analyses of the volcanogenic features are provided. Based on observed petrographical features, we interpret the pseudohieroglyphs to probably represent unique examples of chaotic horizontal columnar jointing. Following the geomorphological and petrographic examination of the study site, we analyse current Faroese legislation aiming at nature conservation and use this case to discuss broader implications of geoheritage conservation and geotourism in distant regions.

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Petrogenesis of Cenozoic high-Mg (picritic) volcanic rocks in the České středohoří Mts. (Bohemian Massif, Czech Republic)

et al. 2021

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Tachylyte in Cenozoic basaltic lavas from the Czech Republic and Iceland: contrasting compositional trends

Cited by 3 publications

References 43 publications

Chemistry and Sr-Nd isotope signature of amphiboles of the magnesio-hastingsite–pargasite–kaersutite series in Cenozoic volcanic rocks: Insight into lithospheric mantle beneath the Bohemian Massif

Chemistry and Sr-Nd isotope signature of amphiboles of the magnesio-hastingsite–pargasite–kaersutite series in Cenozoic volcanic rocks: Insight into lithospheric mantle beneath the Bohemian Massif

Basaltic Dyke with Specific Volcanogenic Structures and Its Geomorphic Evolution: Unique Geoheritage of the Faroe Islands (North Atlantic Ocean)

Petrogenesis of Cenozoic high-Mg (picritic) volcanic rocks in the České středohoří Mts. (Bohemian Massif, Czech Republic)

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