Subduction-related melt refertilisation and alkaline metasomatism in the Eastern Transylvanian Basin lithospheric mantle: Evidence from mineral chemistry and noble gases in fluid inclusions

Faccini, Barbara; Rizzo, Andrea Luca; Bonadiman, Costanza; Ntaflos, Theodoros; Seghedi, Ioan; Grégoire, Marilaure; Ferretti, Giacomo; Coltorti, Massimo

doi:10.1016/j.lithos.2020.105516

Cited by 14 publications

(22 citation statements)

References 104 publications

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“…We envisage this enrichment to have occurred during the ascent of primitive magmas through the lithosphere, which was previously metasomatised by LILE-rich fluids which precipitated hydrous phases such as amphibole. This is consistent with the amphibole-bearing lithospheric mantle xenoliths observed in Perșani, which clearly reflect enrichment by subduction-related hydrous metasomatic components (Faccini et al 2020;Falus et al 2008).…”

Section: Perșani: Interaction Of Asthenospheric Melts With Metasomatisupporting

confidence: 86%

“…Lithospheric mantle xenoliths brought up in close proximity, in Perșani (e.g. Faccini et al 2020;Vaselli et al 1995), provide evidence for just such a process beneath the area.…”

Section: Southern Harghita: Hydrous Metasomatic Phases In the Sourcementioning

confidence: 99%

“…Perșani lavas appear to reflect melt derivation from an OIB-like, asthenospheric source (Downes et al 1995;Seghedi et al 2004b. The ultramafic mantle xenoliths entrained in the magmas have been interpreted to reflect re-fertilisation of the lithospheric mantle by a subductionrelated melt and interaction with an alkaline metasomatic agent (Faccini et al 2020;Downes et al 1995;Vaselli et al 1995). Perșani basalts collectively exhibit minor, though distinct, compositional enrichments compared to other alkali basalts in the Pannonian Basin, a feature which has been ascribed to a subduction-related component beneath the area (Embey-Isztin et al 1993;Downes et al 1995;Embey-Isztin and Dobosi 1995;Seghedi et al 2004b).…”

Section: Na-alkaline Magmatism In Perșanimentioning

confidence: 99%

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Asthenosphere-induced melting of diverse source regions for East Carpathian post-collisional volcanism

Gartner

Seghedi

Nikogosian

et al. 2020

Contrib Mineral Petrol

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The occurrence of post-subduction magmatism in continental collision zones is a ubiquitous feature of plate tectonics, but its relation with geodynamic processes remains enigmatic. The nature of mantle sources in these settings, and their interaction with subduction-related components, are difficult to constrain using bulk rocks when magmas are subject to mixing and assimilation within the crust. Here we examine post-collisional magma sources in space and time through the chemistry of olivine-hosted melt inclusions and early-formed minerals (spinel, olivine and clinopyroxene) in primitive volcanic rocks from the Neogene-Quaternary East Carpathian volcanic range in Călimani (calc-alkaline; 10.1-6.7 Ma), Southern Harghita (calc-alkaline to shoshonitic; 5.3-0.03 Ma) and the Perșani Mountains (alkali basaltic; 1.2-0.6 Ma). Călimani calc-alkaline parental magma compositions indicate a lithospheric mantle source metasomatised by ~ 2% sediment-derived melts, and are best reproduced by ~ 2-12% melting. Mafic K-alkaline melts in Southern Harghita originate from a melt-and fluidmetasomatised lithospheric mantle source containing amphibole (± phlogopite), by ~ 5% melting. Intraplate Na-alkaline basalts from Racoș (Perșani) reflect small-degree (1-2%) asthenosphere-derived parental melts which experienced minor interaction with metasomatic components in the lithosphere. An important feature of the East Carpathian post-collisional volcanism is that the lithospheric source regions are located in the lower plate (distal Europe-Moesia), rather than the overriding plate (Tisza-Dacia). The volcanism appears to have been caused by (1) asthenospheric uprise following slab sinking and possibly south-eastward propagating delamination and breakoff, which induced melting of the subduction-modified lithospheric mantle (Călimani to Southern Harghita); and (2) decompression melting as a consequence of minor asthenospheric upwelling (Perșani).

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Section: Perșani: Interaction Of Asthenospheric Melts With Metasomatisupporting

confidence: 86%

“…Lithospheric mantle xenoliths brought up in close proximity, in Perșani (e.g. Faccini et al 2020;Vaselli et al 1995), provide evidence for just such a process beneath the area.…”

Section: Southern Harghita: Hydrous Metasomatic Phases In the Sourcementioning

confidence: 99%

Section: Na-alkaline Magmatism In Perșanimentioning

confidence: 99%

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Asthenosphere-induced melting of diverse source regions for East Carpathian post-collisional volcanism

Gartner

Seghedi

Nikogosian

et al. 2020

Contrib Mineral Petrol

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“…Figure 8a compares the mineral mode of the source, calculated for a spinel peridotite whose bulk composition is the same as that of the source used in the inversions (Ol 0.58 Opx 0.27 Cpx 0.12 Sp 0.03 ), to the average of that observed in the nodules. In addition, Figure 8b compares the average composition of “LREE‐depleted” clinopyroxenes in nodules from the NW (Dobosi et al., 2010; Embey‐Isztin et al., 2014), N (Liptai et al., 2017), and SE (Faccini et al., 2020)—which are thought to represent the unmetasomatized, or “precursor,” mantle beneath their respective regions—with that calculated for clinopyroxene in the source, also at depths where spinel is stable. Both the expected mineral mode and the clinopyroxene composition of the basalt source closely resemble that of the nodule suites and are consistent with their representing the basalt source rock.…”

Section: Resultsmentioning

confidence: 99%

“…The dashed line in Figure 5m shows the concentration ratios resulting from such a model, which can accurately reproduce the observed pattern for Perşani. Mantle nodules brought up in Perşani show that lithospheric domains have undergone just such an evolution (Downes et al., 1992; Faccini et al., 2020; Vaselli et al., 1995).…”

Section: Resultsmentioning

confidence: 99%

Estimates of the Temperature and Melting Conditions of the Carpathian‐Pannonian Upper Mantle From Volcanism and Seismology

Gartner

McKenzie

2020

Geochem Geophys Geosyst

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What drives the formation of basaltic melts beneath intraplate volcanoes not associated with extensive thermal anomalies or lithospheric extension? Detailed constraints on the melting conditions and source region are imperative to resolve this question. Here we model the geochemistry of alkali basalts and mantle nodules brought up by young (12-0.1 Ma) intraplate volcanoes distributed across the Carpathian-Pannonian region and combine the results with geophysical observations. Rare earth element inversion and forward calculation of elemental concentrations show that the basalts require the mantle to have undergone less than 1% melting in the garnet-spinel transition zone, at depths of about 63-72 km. The calculated melt distributions correspond to a mantle potential temperature of ∼1257°C, equivalent to a real temperature of 1290°C at 65 km beneath the Pannonian Basin. The composition, modal mineralogy, and clinopyroxene geochemistry of some of the entrained mantle nodules closely resemble the basalt source, though the latter equilibrated at greater depths. The gravity anomalies and topography of the Basin reveal no large-scale features that can account for the post-extensional volcanism. Instead, the lithospheric thickness and geotherm show that melting occurs because the base of the lithosphere, at ∼50-km depth, is close to or at the solidus temperature over a large part of the Basin. Hence, only a small amount of upwelling is required to produce minor volumes (up to a few cubic kilometers) of melt. We conclude that the Pannonian volcanism originates from upwelling in the asthenosphere just below thinned lithosphere, which is likely to be driven by thermal buoyancy. Plain Language Summary On Earth's continents, there are surprising instances of basaltic volcanism that are not related to plate stretching or hotspots. To understand just such activity in the Carpathian-Pannonian region, in eastern central Europe, during the last 12 million years, we studied the chemical composition of the erupted lavas. Using a computer code that takes as input the concentrations of elements in basaltic rocks, we calculated the fraction of melt and the depth at which it formed within Earth's mantle. We find that the mantle has undergone less than 1% melting in the garnet-spinel transition zone-a region at about 63-to 72-km depth where these minerals both occur. Using a model of mantle melting, we find that the temperature of the mantle at 65 km below the Pannonian Basin is about 1290°C. The plate's thickness and the temperature variations with depth tell us that the magma source region is at a temperature close to that at which melting begins (the solidus). This means that if mantle material is moved upwards just slightly, it will produce small volumes of melt that can rise to the surface. The most likely cause of such upward movement is convection in the mantle below the rigid plate.

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The composition of fluids stored in the central Mexican lithospheric mantle: Inferences from noble gases and CO2 in mantle xenoliths

et al. 2021

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Subduction-related melt refertilisation and alkaline metasomatism in the Eastern Transylvanian Basin lithospheric mantle: Evidence from mineral chemistry and noble gases in fluid inclusions

Cited by 14 publications

References 104 publications

Asthenosphere-induced melting of diverse source regions for East Carpathian post-collisional volcanism

Asthenosphere-induced melting of diverse source regions for East Carpathian post-collisional volcanism

Estimates of the Temperature and Melting Conditions of the Carpathian‐Pannonian Upper Mantle From Volcanism and Seismology

The composition of fluids stored in the central Mexican lithospheric mantle: Inferences from noble gases and CO2 in mantle xenoliths

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