The Lami pyroclastic succession (Lipari, Aeolian Islands): A clue for unravelling the eruptive dynamics of the Monte Pilato rhyolitic pumice cone

Davì, M.; Rosa, R. De; Donato, Paola; Sulpizio, Roberto

doi:10.1016/j.jvolgeores.2010.09.010

Cited by 30 publications

(23 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Compositionally the lava is calc-alkaline, and contains approximately 74 wt.% SiO 2 , 5 wt.% K 2 O and b1 wt.% H 2 O (Pichler, 1980;Gottsman & Dingwell, 2001;Davì et al, 2010;Lanzo et al, 2010). A high alkali content and an eruptive temperature of N850°C (Cas & Wright, n.d.;Davì, 2007) have been used to explain the anomalous length of the RR, as these factors lower magma viscosity and increase mobility of obsidian flows (Davì et al, 2011;Forni et al, 2013).…”

Section: Rocche Rosse Flow Descriptionmentioning

confidence: 99%

“…It is thought that the lava is the result of fractional crystallisation of a latitic magma, with a degree of crustal assimilation (Davì et al, 2009;Davì et al, 2010;Davì et al, 2011). These authors infer that an injection of a more mafic melt was the trigger for the explosive phase of the eruption (Davì et al, 2011).…”

Section: Rocche Rosse Flow Descriptionmentioning

confidence: 99%

“…Rather shear deformation processes occurring down to microscopic scales during weeks of surface flow (Gottsman & Dingwell, 2001) overprint any flow-scale morphology. The dominant effect of surface deformation on observed textures may be a symptom of the high-alkali calc-alkaline composition and high eruptive temperature, which produce a less viscous and more mobile obsidian lava, prolonging viscous flow (Davì, 2007;Davì et al, 2011;Forni et al, 2013). Using the model of (Giordano et al, 2008), RR composition data from (Gottsman & Dingwell, 2001) and an eruptive temperature of 850 C (Cas & Wright, n.d.;Davì, 2007), a melt viscosity on the order of 10 8 -10 9 Pa s is calculated for the RR.…”

Section: Role Of Heterogeneities On Structural Evolution Of An Obsidimentioning

confidence: 99%

See 2 more Smart Citations

Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

Shields

Mader

Caricchi

et al. 2016

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

Obsidian flow emplacement is a complex and understudied aspect of silicic volcanism. Of particular importance is the question of how highly viscous magma can lose sufficient gas in order to erupt effusively as a lava flow. Using an array of methods we study the extreme textural heterogeneity of the Rocche Rosse obsidian flow in Lipari, a 2 km long, 100 m thick,~800 year old lava flow, with respect to outgassing and emplacement mechanisms. 2D and 3D vesicle analyses and density measurements are used to classify the lava into four textural types: 'glassy' obsidian (b15% vesicles), 'pumiceous' lava (N 40% vesicles), high aspect ratio, 'shear banded' lava (20-40% vesicles) and low aspect ratio, 'frothy' obsidian with 30-60% vesicles. Textural heterogeneity is observed on all scales (m to μm) and occurs as the result of strongly localised strain. Magnetic fabric, described by oblate and prolate susceptibility ellipsoids, records high and variable degrees of shearing throughout the flow. Total water contents are derived using both thermogravimetry and infrared spectroscopy to quantify primary (magmatic) and secondary (meteoric) water. Glass water contents are between 0.08-0.25 wt.%. Water analysis also reveals an increase in water content from glassy obsidian bands towards 'frothy' bands of 0.06-0.08 wt.%, reflecting preferential vesiculation of higher water bands and an extreme sensitivity of obsidian degassing to water content. We present an outgassing model that reconciles textural, volatile and magnetic data to indicate that obsidian is generated from multiple shear-induced outgassing cycles, whereby vesicular magma outgasses and densifies through bubble collapse and fracture healing to form obsidian, which then re-vesiculates to produce 'dry' vesicular magma. Repetition of this cycle throughout magma ascent results in the low water contents of the Rocche Rosse lavas and the final stage in the degassing cycle determines final lava porosity. Heterogeneities in lava rheology (vesicularity, water content, microlite content, viscosity) play a vital role in the structural evolution of an obsidian flow and overprint flow-scale morphology. Post-emplacement hydration also depends heavily on local strain, whereby connectivity of vesicles as a result of shear deformation governs sample rehydration by meteoric water, a process previously correlated to lava vesicularity alone.

show abstract

Section: Rocche Rosse Flow Descriptionmentioning

confidence: 99%

Section: Rocche Rosse Flow Descriptionmentioning

confidence: 99%

Section: Role Of Heterogeneities On Structural Evolution Of An Obsidimentioning

confidence: 99%

See 1 more Smart Citation

Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

Shields

Mader

Caricchi

et al. 2016

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

show abstract

“…The morphologies of volcanic ash with sizes ranging between 90 and 125 μm (i.e., 3.5 b ϕ b − 3) are thought to give details on magma fragmentation processes, and on the post-fragmentation history of juvenile fragments (e.g., Heiken and Wohletz, 1985;Dellino and La Volpe, 1995;Davì et al, 2011). They reflect fragmentation by thermohydraulic explosion processes purely based on the physics of Molten Fuel-Coolant Interaction (MFCI) (e.g., Zimanowski et al, 1997;Büttner et al, 2002).…”

Section: Morphoscopic Analysismentioning

confidence: 99%

Towards the reconstruction of the shallow plumbing system of the Barombi Mbo Maar (Cameroon) Implications for diatreme growth processes of a polygenetic maar volcano

Tchamabé

Ohba

Keresztúri

et al. 2015

Journal of Volcanology and Geothermal Research

View full text Add to dashboard Cite

a b s t r a c tUnderstanding the mechanisms involved in the formation of maars and their diatreme growth processes has been a subject of contention. While there is no direct evidence of the presence of diatremes beneath most of the young maars, their existence is inferred based on the amount and type of country rocks excavated at different depths and deposited as pyroclastic ejecta around their craters. Properly tracing fragmented country rocks in ejecta to interpret their depths of origin and thus the depths of phreatomagmatic explosions require good and detailed information on the substrate geology that is generally lacking at many maars. As an alternative, this paper explores the role of juvenile components in deposits of a maar for understanding the cratering and growth of diatremes during maar-forming eruptions. Based on field investigations, pyroclast distribution, componentry and grain morphology examinations this study reports on the eruptive mechanisms that led to the formation of the Barombi Mbo Maar (BMM), a polygenetic maar volcano in Cameroon. The BMM consists of three diatremes that formed during distinct eruptive events and coalesced to produce an "amalgamated maar-diatreme". Two end-member types of eruption styles from the "dry" magmatic to the "wet" phreatomagmatic explosions governed the formation of the maar. In total, a minimum of~0.0658 km 3 of magma (Dense Rock Equivalent corrected) was ejected based on calculation by applying interpolation techniques on digital elevation models obtained from SRTM30m data corrected by rock textural data collected from the field. The distribution of juvenile clasts throughout the stratigraphic sequence suggests a complex subsurface eruptive process, which originated probably within the uppermost part of the diatreme. From the distribution and morphology of juvenile clasts in the deposits, it is inferred that cratering and country rock excavation during the growth of each of the small diatremes developed mainly from shallow level explosions, sometimes with lateral and vertical variations in the position of the explosion loci. A prospective juvenile-based conceptual model is proposed for the formation of the BMM. The model suggests that, during maar-forming eruptions, explosions taking place at a deeper position might entrain extensive amount of lithics from the mostly lithic-dominated upper crater infill to deposit juvenile-poor (b10 vol.%) tephra beds. Layers with a juvenile content of 10-60 vol.%, for example, might result from deep to shallow-seated explosions, with a common entrainment of lithics from the crater infill region, and with much of the remobilized tephra being transported to the ejecta ring sequence. In contrast, explosions occurring at shallower positions will produce mainly juvenile-rich beds (juvenile N 90 vol.%).

show abstract

“…For example, arrival of gas rich magma in a magmatic system or magma evolution within the chamber itself are usually claimed for explaining transitions from effusive to explosive eruptions, even in cases in which the geological evidences are lacking (i.e., the erupted material is poorly vesicular, as in the case of many basaltic eruptions; Fink et al, 1992;Wylie et al, 1999). In other cases, the arrival of fresh magma into a magma chamber is postulated as trigger magma chamber rupture and eventually fed an eruption, even in the absence of petrological evidences (i.e., mingling and mixing; e.g., Davì et al, 2011). All these considerations claim for discussion about the state of the art and perspectives about the interplay between volcanic activity and changes in the stress field.…”

Section: Introductionmentioning

confidence: 99%

Influence of Stress Field Changes on Eruption Initiation and Dynamics: A Review

Sulpizio

Massaro

2017

Front. Earth Sci.

View full text Add to dashboard Cite

We review here three main (first-order) mechanisms of stress variation able to influence the triggering of volcanic eruptions and the possible impact on eruption dynamics. They are short-and long-term unloading, seismic energy effects, and changes in far field stress due to geodynamic processes. We present an equilibrium equation for rupture of magma chamber and opening of a dyke up to the surface, taking into account the contribution of each mechanism within the equation. The equation considers the effect of possible superimposition of the three mechanisms with internal processes to the magmatic system, and it is also used for discussing the possible influence on eruption dynamics. The different possible contribution to the eruption triggering are discussed for each mechanism, highlighting how, in many cases, a single mechanism alone is not sufficient for driving eruptive activity if the magmatic system is not close to eruptive conditions.

show abstract

The Lami pyroclastic succession (Lipari, Aeolian Islands): A clue for unravelling the eruptive dynamics of the Monte Pilato rhyolitic pumice cone

Cited by 30 publications

References 54 publications

Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

Unravelling textural heterogeneity in obsidian: Shear-induced outgassing in the Rocche Rosse flow

Towards the reconstruction of the shallow plumbing system of the Barombi Mbo Maar (Cameroon) Implications for diatreme growth processes of a polygenetic maar volcano

Influence of Stress Field Changes on Eruption Initiation and Dynamics: A Review

Contact Info

Product

Resources

About