Textural characterization, major and volatile element quantification and Ar–Ar systematics of spherulites in the Rocche Rosse obsidian flow, Lipari, Aeolian Islands: a temperature continuum growth model

Clay, P. L.; O’Driscoll, Brian; Gertisser, Ralf; Busemann, H.; Sherlock, Sarah C.; Kelley, Simon P.

doi:10.1007/s00410-012-0813-x

Cited by 24 publications

(18 citation statements)

References 68 publications

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“…Spherulites are radial fibrous crystallites, considered to progressively nucleate as a down temperature continuum during syn-and post-emplacement cooling (Lofgren 1971;Swanson 1977;McArthur et al 1998;Gardner et al 2012;Breitkreuz 2013;Clay et al 2013;Bullock et al 2017). Differences in spherulite abundance (often manifested as trails), crystallinity, vesicularity and glass chemistry can all define flow foliation in rhyolite (Gonnermann and Manga 2005;Clay et al 2013;Bullock et al 2017).…”

Section: Lithofacies Of Rhyolitic Lava Flowsmentioning

confidence: 99%

“…The arrangement of spherulites, microlites and vesicles defines the foliation in the obsidian lithofacies of the flow (Clay et al 2013;Bullock et al 2017), making it possible to recognise and measure planar structures (Figs. 5, 6 and 7; Table 1, Electronic supplementary material 1).…”

Section: Flow Foliationsmentioning

confidence: 99%

“…5, 6 and 7; Table 1, Electronic supplementary material 1). Flow foliations are generally continuous across several metres, although they may be truncated or disrupted by small brittle faults that have a few centimetres of displacement (Clay et al 2013). Throughout the flow, foliations are disrupted by flow-wide conjugate fracturing and tension gashes, both up to 10 cm in length.…”

Section: Flow Foliationsmentioning

confidence: 99%

“…Strain localisation affects the rheological behaviour of lavas, and rheological contrasts between layers, such as differences in viscosity, capillary number and yield strength (Castro and Cashman 1999;Gonnerman and Manga 2005;Shields et al 2016), can promote shear zonation. Due to the high viscosity of flowing rhyolitic lavas, the last increments of flow-related strain are recorded in the structures that are evident in the final solidified flow (Clay et al 2013).…”

Section: Crust Formationmentioning

confidence: 99%

“…Previous work on the Rocche Rosse has focused on fragmentation and transport mechanisms of the associated pyroclastic sequence (Dellino and La Volpe 1995), the thermal history of flow frontal ramps, i.e. ridges of fold structures extending downward into the flow by tens of metres (Gottsmann and Dingwell 2001), magmatic history (Gioncada et al 2003(Gioncada et al , 2005Davì et al 2009Davì et al , 2010 and textural heterogeneity (Gonnermann and Manga 2003;Clay et al 2013;Shields et al 2016). Ramp structures of the Rocche Rosse were also documented by Hall (1978) and Cas and Wright (1987), inferring a compressive regime and build-up of lava behind a brecciated flow front, hindering flow advance.…”

Section: Introductionmentioning

confidence: 99%

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Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

2018

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The Rocche Rosse lava flow marks the most recent rhyolitic extrusion on Lipari island (Italy), and preserves evidence for a multi-stage emplacement history. Due to the viscous nature of the advancing lava (10 8 to 10 10 Pa s), indicators of complex emplacement processes are preserved in the final flow. This study focuses on structural mapping of the flow to highlight the interplay of cooling, crust formation and underlying slope in the development of rhyolitic lavas. The flow is made up of two prominent lobes, small (< 0.2 m) to large (> 0.2 m) scale folding and a channelled geometry. Foliations dip at 2-4°over the flatter topography close to the vent, and up to 30-50°over steeper mid-flow topography. Brittle faults, tension gashes and conjugate fractures are also evident across flow. Heterogeneous deformation is evident through increasing fold asymmetry from the vent due to downflow cooling and stagnation. A steeper underlying topography mid-flow led to development of a channelled morphology, and compression at topographic breaks resulted in fold superimposition in the channel. We propose an emplacement history that involved the evolution through five stages, each associated with the following flow regimes: (1) initial extrusion, crustal development and small scale folding; (2) extensional strain, stretching lineations and channel development over steeper topography; (3) compression at topographic break, autobrecciation, lobe development and medium scale folding; (4) progressive deformation with stagnation, large-scale folding and refolding; and (5) brittle deformation following flow termination. The complex array of structural elements observed within the Rocche Rosse lava flow facilitates comparisons to be made with actively deforming rhyolitic lava flows at the Chilean volcanoes of Chaitén and Cordón Caulle, offering a fluid dynamic and structural framework within which to evaluate our data.

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Section: Lithofacies Of Rhyolitic Lava Flowsmentioning

confidence: 99%

Section: Flow Foliationsmentioning

confidence: 99%

Section: Flow Foliationsmentioning

confidence: 99%

Section: Crust Formationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Emplacement of the Rocche Rosse rhyolite lava flow (Lipari, Aeolian Islands)

2018

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Subaqueous felsic volcanic sequence and its contribution to the ancient alkaline lacustrine deposits in the Mahu Sag, Junggar Basin, NW China

Zhang

et al. 2023

Geological Journal

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Subaqueous eruptions alter the chemical conditions of the lake by intensifying the interaction between hot volcanic rocks and water, resulting in the exchange of alkalis. The lower part of the Fengcheng Formation in the Mahu Sag, NW China, has abundant rhyolitic welded tuff and related pyroclastic deposits, which were deposited under ancient alkaline lacustrine deposits of the Fengcheng Formation. Despite this, the effect of the eruption process on the formation of the alkali lake remains unclear. To gain a better understanding of the eruptive behaviour and emplacement processes, detailed drilling core descriptions, microscopic observations, and interpretations of textural characteristics of rhyolitic welded tuff units and adjacent volcano‐sedimentary associations have been conducted. The rhyolitic welded tuff can be categorized into seven lithofacies units based on the degree of welding, devitrification characteristics, pore development, and filling characteristics. The age of eruption was determined through zircon U–Pb dating of the rhyolitic welded tuff, revealing it to be approximately 300 Ma, thereby providing constraints on the deposition time of alkaline lacustrine deposits. Mudstones that encase the welded tuff unit and quenched structures such as perlitic fractures, quench cracks of spherulite and lithophysae, and chalcedony spherules indicate that the welded tuff unit was formed through subaqueous eruption. Alkali fractionation (sodium and potassium) occurs in the spherulite and lithophysae zone and at the top condensation boundary, demonstrating that the subaqueous eruption process significantly enhanced devitrification and hydration, causing sodium to escape from the welded tuff and released into the lake water as sodium ions. The rhyolitic welded tuff provides evidence of the evolution of a subaqueous felsic eruption where the water‐rock reaction played a fundamental role in alkalizing the lake by providing the lake with sodium ions in Mahu Sag.

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