The relationship between potassic, calc-alkaline and Na-alkaline magmatism in South Italy volcanoes: A melt inclusion approach

2004 ◽  
Vol 220 (1-2) ◽  
pp. 121-137 ◽  
Author(s):  
Pierre Schiano ◽  
Robert Clocchiatti ◽  
Luisa Ottolini ◽  
Alessandro Sbrana
Keyword(s):  
Melt Inclusion ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
South Italy ◽  
The Relationship

scholarly journals 207Pb-206Pb dating of magnetite, monazite and allanite in the central and northern Nagssugtoqidian orogen, West Greenland

2006 ◽  
Vol 11 ◽  
pp. 101-114 ◽  
Author(s):  
Henrik Stendal ◽  
Karsten Secher ◽  
Robert Frei
Keyword(s):  
Hydrothermal Activity ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
Isotopic Data ◽  
Sulphide Deposit ◽  
Late Archaean ◽  
West Greenland ◽  
Isotopic Signatures ◽  
Source Characteristics ◽  
Isotopic Measurements

Pb-isotopic data for magnetite from amphibolites in the Nagssugtoqidian orogen, central West Greenland, have been used to trace their source characteristics and the timing of metamorphism. Analyses of the magnetite define a Pb-Pb isochron age of 1726 ± 7 Ma. The magnetite is metamorphic in origin, and the 1726 Ma age is interpreted as a cooling age through the closing temperature of magnetite at ~600°C. Some of the amphibolites in this study come from the Naternaq supracrustal rocks in the northern Nagssugtoqidian orogen, which host the Naternaq sulphide deposit and may be part of the Nordre Strømfjord supracrustal suite, which was deposited at around 1950 Ma ago. Pb-isotopic signatures of magnetite from the Arfersiorfik quartz diorite in the central Nagssugtoqidian orogen are compatible with published whole-rock Pb-isotopic data from this suite; previous work has shown that it is a product of subduction-related calc-alkaline magmatism between 1920 and 1870 Ma. Intrusion of pegmatites occurred at around 1800 Ma in both the central and the northern parts of the orogen. Pegmatite ages have been determined by Pb stepwise leaching analyses of allanite and monazite, and source characteristics of Pb point to an origin of the pegmatites by melting of the surrounding late Archaean and Palaeoproterozoic country rocks. Hydrothermal activity took place after pegmatite emplacement and continued below the closure temperature of magnetite at 1800– 1650 Ma. Because of the relatively inert and refractory nature of magnetite, Pb-isotopic measurements from this mineral may be of help to understand the metamorphic evolution of geologically complex terrains.

Fluids composition in the mantle beneath the Eastern Transylvanian Basin inferred from mineral chemistry and noble gases in fluid inclusions of ultramafic xenoliths

2021 ◽  
Author(s):  
Andrea Luca Rizzo ◽  
Barbara Faccini ◽  
Costanza Bonadiman ◽  
Theodoros Ntaflos ◽  
Ioan Seghedi ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Noble Gases ◽  
Mineral Chemistry ◽  
Mantle Xenoliths ◽  
Alkaline Magmatism ◽  
Volcanic Area ◽  
Crustal Material ◽  
Calc Alkaline ◽  
Depleted Mantle ◽  
Magmatic Gases

<p>The investigation of noble gases (He, Ne, Ar) and CO<sub>2</sub> in fluid inclusions (FI) of mantle-derived rocks from the Sub Continental Lithospheric Mantle (SCLM) is crucial for constraining its geochemical features and evolution as well as the volatiles cycle, and for better evaluating the information arising from the study and monitoring of volcanic and geothermal gases. Eastern Transylvanian Basin in Romania is one of the places in Central-Eastern Europe where mantle xenoliths are brought to the surface by alkaline magmatism, offering the opportunity for applying the above-mentioned approach. Moreover, this locality is one of the few places on Earth where alkaline eruptions occurred contemporaneously with calc-alkaline activity, thus being a promising area for the investigation of subduction influence on the magma sources and volatiles composition.</p><p>In this work, we studied petrography, mineral chemistry and noble gases in FI of mantle xenoliths found in Perşani Mts. alkaline volcanic products. Our findings reveal that the local mantle recorded two main events. The first was a pervasive, complete re-fertilization of a previously depleted mantle by a calc-alkaline subduction-related melt, causing the formation of very fertile, amphibole-bearing lithotypes. Fluids involved in this process and trapped in olivine, opx and cpx, show <sup>4</sup>He/<sup>40</sup>Ar* ratios up to 1.2 and among the most radiogenic <sup>3</sup>He/<sup>4</sup>He values of the European mantle (5.8 ± 0.2 Ra), reflecting the recycling of crustal material in the local lithosphere. The second event is related to a later interaction with an alkaline metasomatic agent similar to the host basalts, that caused slight LREE enrichment in pyroxenes and crystallization of disseminated amphiboles, with FI showing <sup>4</sup>He/<sup>40</sup>Ar* and <sup>3</sup>He/<sup>4</sup>He values up to 2.5 and 6.6 Ra, respectively, more typical of magmatic fluids.</p><p>Although volcanic activity in the Perşani Mts. is now extinct, strong CO<sub>2</sub> degassing (8.7 × 10<sup>3</sup> t/y) in the neighbouring Ciomadul volcanic area may indicate that magma is still present at depth (Kis et al., 2017; Laumonier et al., 2019). The gas manifestations present from Ciomadul area are the closest to the outcrops containing mantle xenoliths for comparison of the noble gas composition in FI. <sup>3</sup>He/<sup>4</sup>He values from Stinky Cave (Puturosul), Doboşeni and Balvanyos are up to 3.2, 4.4 and 4.5 Ra, respectively, indicating the presence of a cooling magma (Vaselli et al., 2002 and references therein). In the same area and more recently, Kis et al. (2019) measured <sup>3</sup>He/<sup>4</sup>He ratios up to 3.1 Ra, arguing that these values indicate a mantle lithosphere strongly contaminated by subduction-related fluids and post-metasomatic ingrowth of radiogenic <sup>4</sup>He. Our findings consider more likely that magmatic gases from Ciomadul volcano are not representative of the local mantle but are being released from a cooling and aging magma that resides within the crust. Alternatively, crustal fluids contaminate magmatic gases while they are rising to the surface.</p><p> </p><p>Kis et al. (2017). Journal of Volcanology and Geothermal Research 341, 119–130.</p><p>Kis et al. (2019) Geochem. Geophys. Geosyst. 20, 3019-3043.</p><p>Laumonier et al. (2019) Earth and Planetary Science Letters, 521, 79-90.</p><p>Vaselli et al. (2002) Chemical Geology 182, 637–654.</p>

scholarly journals A step towards unraveling the paleogeographic attribution of pre-Mesozoic basement complexes in the Western Alps based on U–Pb geochronology of Permian magmatism

2020 ◽  
Vol 113 (1) ◽  
Author(s):  
Michel Ballèvre ◽  
Audrey Camonin ◽  
Paola Manzotti ◽  
Marc Poujol
Keyword(s):  
Early Stage ◽  
Western Alps ◽  
Geochemical Data ◽  
Alkaline Magmatism ◽  
Low Grade ◽  
Calc Alkaline ◽  
Alpine Orogeny ◽  
History Of ◽  
External Part ◽  
The One

Abstract The Briançonnais Domain (Western Alps) represented the thinned continental margin facing the Piemonte-Liguria Ocean, later shortened during the Alpine orogeny. In the external part of the External Briançonnais Domain (Zone Houillère), the Palaeozoic basement displays microdioritic intrusions into Carboniferous sediments and andesitic volcanics resting on top of the Carboniferous sediments. These magmatic rocks are analysed at two well-known localities (Guil volcanics and Combarine sill). Geochemical data show that the two occurrences belong to the same calc-alkaline association. LA-ICP-MS U–Pb ages have been obtained for the Guil volcanics (zircon: 291.3 ± 2.0 Ma and apatite: 287.5 ± 2.6 Ma), and the Combarine sill (zircon: 295.9 ± 2.6 Ma and apatite: 288.0 ± 4.5 Ma). These ages show that the calc-alkaline magmatism is of Early Permian age. During Alpine orogeny, a low-grade metamorphism, best recorded by lawsonite-bearing veins in the Guil andesites, took place at about 0.4 GPa, 350 °C in the External Briançonnais and Alpine metamorphism was not able to reset the U–Pb system in apatite. The Late Palaeozoic history of the Zone Houillère is identical to the one recorded in the Pinerolo Unit, located further East in the Dora-Maira Massif, and having experienced a garnet-blueschist metamorphism during the Alpine orogeny. The comparison of these two units allows for a better understanding of the link between the Palaeozoic basements, mostly subducted during the Alpine convergence, and their Mesozoic covers, generally detached at an early stage of the convergence history.

Magnetite–apatite intrusions and calc-alkaline magmatism, Camsell River, N.W.T.

1976 ◽  
Vol 13 (2) ◽  
pp. 348-354 ◽  
Author(s):  
J. P. N. Badham ◽  
R. D. Morton
Keyword(s):  
Volcanic Rocks ◽  
Orogenic Belt ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
Immiscible Liquids ◽  
Intermediate Composition ◽  
Andean Type

The Camsell River area comprises a roof pendant of volcanic rocks within an Aphebian (~1800 m.y.) orogenic belt. Magnetite–apatite intrusions and related bodies are common and are closely associated with plutons of intermediate composition. The magnetitic intrusions are interpreted as immiscible liquids that separated from a magma of intermediate composition. The immiscible fractions were predominantly crystalline when they reached their present higher levels, and final emplacement was facilitated by volatile-streaming and fluidization. Their presence in the orogenic belt is taken as further support for the hypothesis that the orogen was of Andean type.

Representations of Greek Tragedy in Ancient Pottery: a Theatrical Perspective

2008 ◽  
Vol 24 (3) ◽  
pp. 229-245
Author(s):  
Christian M. Billing
Keyword(s):  
Fourth Century ◽  
Fifth Century ◽  
Literary Texts ◽  
Extensive Experience ◽  
Ancient Pottery ◽  
South Italy ◽  
The Usa ◽  
The Uk ◽  
The University ◽  
The Relationship

In this article, Christian M. Billing considers the relationship between representations of mythic narratives found on ancient pottery (primarily found at sites relating to the Greek colonies of south Italy in the fourth century BC, but also to certain vases found in Attica) and the tragic theatre of the fifth century BC. The author argues against the current resurgence in critical accounts that seek to connect such ceramics directly to performance of tragedies by the major tragedians: Aeschylus, Sophocles, and Euripides. Using five significant examples of what he considers to be errors of method in recent philologically inspired accounts of ancient pottery, Billing argues for a more nuanced approach to the interpretation of such artefacts – one that moves beyond an understanding of literary texts and art history towards a more performance-conscious approach, while also acknowledging that a multiplicity of spheres of artistic influence, drawn from a variety of artistic media, operated in the production and reception of such artefacts. Christian M. Billing is an academic and theatre practitioner working in the fields of ancient Athenian and early modern English and European drama. He has extensive experience as a director, designer, and actor, and has taught at a number of universities in the UK and the USA. He is currently Lecturer in Drama at the University of Hull.

Suture zones and importance of strike-slip faulting for Variscan geodynamic reconstructions of the External Crystalline Massifs of the western Alps

2009 ◽  
Vol 180 (6) ◽  
pp. 483-500 ◽  
Author(s):  
Stéphane Guillot ◽  
Silvia di Paola ◽  
René-Pierre Ménot ◽  
Patrick Ledru ◽  
Maria Iole Spalla ◽  
...  
Keyword(s):  
Shear Zone ◽  
Bohemian Massif ◽  
Western Alps ◽  
Alkaline Magmatism ◽  
Calc Alkaline ◽  
Geodynamic Evolution ◽  
Central European ◽  
Back Arc ◽  
Eastern Domain ◽  
Geodynamic Reconstructions

Abstract This paper reviews the geodynamic evolution of the Belledonne, Grandes Rousses and Oisans massifs in the western Alps from Early Ordovician to Permian times. Three domains are distinguished. The eastern domain, which includes the NE Belledonne massif and the inner Oisans massif, records the subduction of the Central-European ocean along a NW dipping subduction zone. The western domain is marked by Cambro-Ordovician back-arc rifting (Chamrousse ophiolite) initiating the opening of the Rheic ocean. It was followed by Mid-Devonian obduction of the back-arc Chamrousse ophiolite, towards the NW in relation with the SE dipping subduction of the Saxo-Thuringian ocean. The central domain, including the SW part of the Belledonne massif, the Grandes Rousses massif and the outer Oisans massif, records the Devonian to Carboniferous orogenic activity that produced calc-alkaline magmatism, Mg-K granite intrusions and syn-collisional sedimentation related to Visean nappe stacking that we relate to the closure of the Saxo-Thuringian ocean. Based on tectonostratigraphic correlations we propose that these domains initially correspond to the northeastward extension of the Bohemian massif. During the late Carboniferous, the External Crystalline Massifs including Sardinia and Corsica were stretched towards the SW along the > 600 km long dextral External Crystalline Massifs shear zone. Offset of the Saxo-Thuringian and eo-Variscan suture zones from the Bohemian massif to the ECM suggests a possible dextral displacement of about 300 km along the ECM shear zone.

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