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Tracking Volatile Behaviour in Sub-volcanic Plumbing Systems Using Apatite and Glass: Insights into Pre-eruptive Processes at Campi Flegrei, Italy (2019)

Stock, Michael J. ; Humphreys, Madeleine C. S ; Smith, Victoria C. ; [weitere]

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Publikationsdatum: 2020-12-02

Beschreibung: Volatile elements play an important role in many aspects of the physicochemical architecture of sub-volcanic plumbing systems, from the liquid line of descent to the dynamics of magma storage and eruption. However, it remains difficult to constrain the behaviour of magmatic volatiles on short timescales before eruption using established petrological techniques (e.g. melt inclusions); specifically, in the final days to months of magma storage. This study presents a detailed model of pre-eruptive volatile behaviour in the Campi Flegrei system (Italy), through combined analyses of apatite crystals and glass. The deposits of eight eruptions were examined, covering the full spectrum of melt compositions, eruptive styles and periods of activity at Campi Flegrei in the past 15 kyr. Measured apatite compositions are compared with thermodynamic models that predict the evolution of the crystal compositions during different fractional crystallization scenarios, including (1) volatile-undersaturated conditions, (2) H2O-saturated conditions and (3) varying P–T conditions. The compositions of clinopyroxene-hosted and biotite-hosted apatite inclusions are consistent with crystallization under volatile-undersaturated conditions that persisted until late in magmatic evolution. Apatite microphenocrysts show significantly more compositional diversity, interpreted to reflect a mixed cargo of crystals derived from volatile-undersaturated melts at depth and melts that have undergone cooling and degassing in discrete shallow-crustal magma bodies. Apatite microphenocrysts from lavas show some re-equilibration during cooling at the surface. Clinopyroxene-hosted melt inclusions within the samples typically contain 2–4 wt % H2O, indicating that they have been reset during temporary magma storage at 1–3km depth, similar to the depth of sill emplacement during recent seismic crises at Campi Flegrei. Comparable apatite compositional trends are identified in each explosive eruption analysed, regardless of volume, composition or eruption timing. However, apatites from the different epochs of activity appear to indicate subtle changes in the H2O content of the parental melt feeding the Campi Flegrei system over time. This study demonstrates the potential utility of integrated apatite and glass analysis for investigating pre-eruptive volatile behaviour in apatite-bearing magmas

Beschreibung: Published

Beschreibung: 2463-2491

Beschreibung: 2V. Struttura e sistema di alimentazione dei vulcani

Beschreibung: JCR Journal

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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Late-stage volatile saturation as a potential trigger for explosive volcanic eruptions (2018)

Stock, Michael J. ; Humphreys, Madeleine C. S ; Smith, Victoria C. ; [weitere]

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Publikationsdatum: 2021-03-18

Beschreibung: Magma reservoirs are thought to grow relatively slowly, assembling incrementally under volatile-saturated conditions. Eruptions may be triggered by injections of volatile-rich melt, or generation of over-pressure due to protracted crystallization. Here, we analyse fluorine, chlorine and water in apatite crystals trapped at di erent stages of magma evolution, and in melt inclusions from clinopyroxene and biotite crystals expelled during an explosive eruption of the Campi Flegrei caldera, Italy, about 4,000 years ago. We combine our geochemical analyses with thermodynamic modelling to reconstruct the evolution of magmatic volatile contents leading up to the explosive eruption. We find that the magma reservoir remained persistently water-undersaturated throughout most of its lifetime. Even crystals in contact with the melt shortly before eruption show that the magma was volatile-undersaturated. Our models suggest that the melt reached volatile saturation at low temperatures, just before eruption.We suggest that late-stage volatile saturation probably triggered the eruption, and conclude that ‘priming’ of the magma system for eruption may occur on timescales much shorter than the decadal to centennial timescales thought typical for magma reservoir assembly. Thus, surface deformation pulses that record magma assembly at depth beneath Campi Flegrei and other similar magmatic systems may not be immediately followed by an eruption; and explosive eruptions may begin with little warning.

Beschreibung: Published

Beschreibung: 249-255

Beschreibung: 4V. Dinamica dei processi pre-eruttivi

Beschreibung: JCR Journal

Schlagwort(e): explosive volcanic eruptions ; magma evolution ; volatile saturation

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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Tephra dispersal during the Campanian Ignimbrite (Italy) eruption: implications for ultra-distal ash transport during the large caldera-forming eruption (2018)

Smith, Victoria C. ; Isaia, Roberto ; Engwell, Sam L. ; [weitere]

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Publikationsdatum: 2020-11-19

Beschreibung: The Campanian Ignimbrite eruption dispersed ash over much of the central eastern Mediterranean Sea and eastern Europe. The eruption started with a Plinian phase that was followed by a series of pyroclastic density currents (PDCs) associated with the collapse of the Plinian column and the caldera. The glass compositions of the deposits span a wide geochemical range, but the Plinian fallout and PDCs associated with column collapse, the Lower Pumice Flow, only erupted the most evolved compositions. The later PDCs, the Breccia Museo and Upper Pumice Flow, erupted during and after caldera collapse, tap a less evolved component, and intermediate compositions that represent mixing between the end-members. The range of glass compositions in the Campanian Ignimbrite deposits from sites across the central and eastern Mediterranean Sea allow us to trace the dispersal of the different phases of this caldera-forming eruption. We map the fallout from the Plinian column and the plumes of fine material associated with the PDCs (co-PDCs) across the entire dispersal area. This cannot be done using the usual grain-size methods as deposits in these distal regions do not retain characteristics that allow attribution to either the Plinian or co- PDC phases. The glass compositions of the tephra at ultradistal sites (〉1500 km from the vent) match those of the uppermost PDC units, suggesting that most of the ultra-distal dispersal was associated with the late co-PDC plume that was generated during caldera collapse.

Beschreibung: Published

Beschreibung: 45

Beschreibung: 3V. Proprietà dei magmi e dei prodotti vulcanici

Beschreibung: JCR Journal

Schlagwort(e): Caldera-forming eruption ; Ash dispersal ; Plinian ; Tephra

Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)

Materialart: article

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Refining the Late Quaternary tephrochronology for southern South America using the Laguna Potrok Aike sedimentary record (2019)

Smith, Rebecca E. ; Smith, Victoria C. ; Fontijn, Karen ; [weitere]

PERGAMON-ELSEVIER SCIENCE LTD

In: EPIC3Quaternary Science Reviews, PERGAMON-ELSEVIER SCIENCE LTD, 218, pp. 137-156, ISSN: 0277-3791

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Publikationsdatum: 2019-12-22

Beschreibung: This paper presents a detailed record of volcanism extending back to ~80 kyr BP for southern South America using the sediments of Laguna Potrok Aike (ICDP expedition 5022; Potrok Aike Maar Lake Sediment Archive Drilling Project - PASADO). Our analysis of tephra includes the morphology of glass, the mineral componentry, the abundance of glass-shards, lithics and minerals, and the composition of glass- shards in relation to the stratigraphy. Firstly, a reference database of glass compositions of known eruptions in the region was created to enable robust tephra correlations. This includes data published elsewhere, in addition to new glass-shard analyses of proximal tephra deposits from Hudson (eruption units H1 and H2), Aguilera (A1), Reclus (R1, R2-3), Mt Burney (MB1, MB2, MBx, MB1910) and historical Lautaro/Viedma deposits. The analysis of the ninety-four tephra layers observed in the Laguna Potrok Aike sedimentary sequence reveals that twenty-five tephra deposits in the record are the result of pri- mary fallout and are sourced from at least three different volcanoes in the Austral Andean Volcanic Zone (Mt Burney, Reclus, Lautaro/Viedma) and one in the southernmost Southern Volcanic Zone (Hudson). One new correlation to the widespread H1 eruption from Hudson volcano at 8.7 (8.6e9.0) cal ka BP during the Quaternary is identified. The identification of sixty-five discrete deposits that were pre- dominantly volcanic ashes (glass and minerals) with subtle characteristics of reworking (in addition to three likely reworked tephra, and one unknown layer) indicates that care must be taken in the analysis of both visible and invisible tephra layers to decipher their emplacement mechanisms.

Repository-Name: EPIC Alfred Wegener Institut

Materialart: Article , isiRev

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Geochemical characterisation of the Late Quaternary widespread Japanese tephrostratigraphic markers and correlations to the Lake Suigetsu sedimentary archive (SG06 core) (2019)

Albert, Paul G. ; Smith, Victoria C. ; Suzuki, Takehiko ; [weitere]

Elsevier

In: Quaternary Geochronology, 52 . pp. 103-131.

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Publikationsdatum: 2022-01-07

Beschreibung: Large Magnitude (6–8) Late Quaternary Japanese volcanic eruptions are responsible for widespread ash (tephra) dispersals providing key isochrons suitable for the synchronisation and dating of palaeoclimate archives across East Asia, the NW Pacific and beyond. The transfer of geochronological information using these eruption deposits demands robust tephra correlations underpinned by detailed and precise volcanic glass geochemical data. Presented here is a major (electron microprobe; EMP) and trace element (Laser ablation inductively coupled plasma mass spectrometry; LA-ICP-MS) characterisation of near-source deposits from a series of large magnitude Japanese eruptions spanning approximately the last 150 ka. These data offer new insights into diagnostic compositional variations of the investigated volcanic sources spanning the Japanese islands. Whilst in the case of the highly productive Aso caldera (Kyushu), we are able to explore compositional variations through successive large magnitude eruptions (50–135 ka). These near-source volcanic glass data are used to validate and refine the visible tephrostratigraphy of the intensely dated Lake Suigetsu sedimentary record (SG06 core), Honshu Island, whilst also illustrating key tephrostratigraphic tie points to other East Asian palaeoclimate records (e.g. Lake Biwa). The identification of widespread Japanese tephrostratigraphic markers in the SG06 sediment record enables us to place chronological constraints on these ash dispersals, and consequently explosive volcanism at source volcanoes situated along the Kyushu Arc, including Kikai, Ata and Aso calderas. The proximal Aso-4 Ignimbrite (Magnitude 7.7) deposit is dated here by 40Ar/39Ar at 86.4 ± 1.1 ka (2σ), and provides a chronological anchor (SG06-4963) for the older sediments of the Lake Suigetsu record. Finally, trace element glass data verify visible ash fall layers derived from other compositionally distinct source regions of Japanese volcanism, including activity along the northern Izu-Bonin arc and North East Japan Arcs. These findings underline the Lake Suigetsu record as central node in the Japanese tephrostratigraphic framework. Highlights • Near-source and distal (Lake Suigetsu) characterisation of Late Quaternary widespread Japanese Tephrostratigraphic markers. • Grain-specific major and trace element volcanic glass analyses (EMP & LA-ICP-MS). • Chemical discrimination of Japanese volcanic source regions for the purposes of Tephrochronology. • Unlocking the Lake Suigetsu (SG06 core) visible tephra layers for reliable archive synchronisation. • Proximal 40Ar/39Ar age of 86.4 ± 1.1 ka (2σ) for the Magnitude 7.7 caldera forming Aso-4 eruption.

Materialart: Article , PeerReviewed

Format: text

DOI: 10.1016/j.quageo.2019.01.005

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