Preprints

Filtering by Subject: Volcanology

The shape of volcanic conduits inferred from bubble size distributions

Sahand Hajimirza, Helge M. Gonnermann, James E. Gardner

Published: 2020-11-28
Subjects: Earth Sciences, Volcanology

The most intense known explosive volcanic eruptions on Earth are Plinian eruptions of silicic magma. Geospeedometers indicate that Plinian magma erupts from high pressure within the magma chamber at average speeds of 0.001-1 MPa/s. Concurrently dissolved magmatic volatiles, predominantly water, nucleate about one quadrillion bubbles per cubic meter of melt, preserved as vesicles within tephra. [...]

Boron isotopic signatures of melt inclusions from North Iceland reveal recycled material in the Icelandic mantle source

Margaret Hartley, Oliver Shorttle, Cees-Jan de Hoog

Published: 2020-11-13
Subjects: Earth Sciences, Geochemistry, Geology, Physical Sciences and Mathematics, Volcanology

Trace element and volatile heterogeneity in the Earth's mantle is inuenced by the recycling of oceanic lithosphere through subduction. Oceanic island basalts commonly have high concentrations of volatiles compared to mid-ocean ridge basalts, but the extent to which this enrichment is linked to recycled mantle domains remains unclear. Boron is an ideal tracer of recycled subducted material, [...]

Segment tip geometry of sheet intrusions, II: Field observations of tip geometries and a model for evolving emplacement mechanisms

Tara Louise Stephens, Richard J Walker, David Healy, Alodie Bubeck

Published: 2020-11-03
Subjects: Earth Sciences, Geology, Volcanology

Igneous sheet intrusions are segmented across several orders of magnitude, with segment tip geometry commonly considered indicative of the propagation mechanism (brittle or non-brittle). Proposed propagation mechanisms are inferred to represent host rock mechanical properties during initial magma emplacement; typically, these models do not account for segment sets that show a range of tip [...]

Studying the initiation of volcanic eruptions: Time for a petrological perspective.

Adam J Kent, Christy B Till, Kari M Cooper

Published: 2020-10-28
Subjects: Earth Sciences, Volcanology

Volcano monitoring is essential for mitigating the risks associated with volcanic activity. As monitoring becomes more sophisticated and widespread, there is a growing need for understanding the relationship between different monitoring records and magmatic processes occurring at depth. This is particularly relevant to the processes that initiate eruptions after the extended periods of repose and [...]

Salt-magma interactions influence intrusion distribution and salt tectonics in the Santos Basin, offshore Brazil

Craig Magee, Leonardo Muniz Pichel, Amber Madden-Nadeau, Christopher Aiden-Lee Jackson, Webster Mohriak

Published: 2020-10-25
Subjects: Earth Sciences, Geology, Tectonics and Structure, Volcanology

Many sedimentary basins host thick evaporite (salt) deposits. Some of these basins also host extensive igneous intrusion networks. It thus seems inevitable that, in some locations, magma will interact with salt. Yet how interaction between these materials may influence salt tectonics or magma emplacement, particularly at the basin-scale, remains poorly understood. We use 3D seismic reflection [...]

Was the Kalkarindji continental flood basalt province a driver of environmental change at the dawn of the Phanerozoic?

Peter Marshall, Luke E Faggetter, Mike Widdowson

Published: 2020-10-22
Subjects: Paleobiology, Volcanology

The Kalkarindji continental flood basalt province of Northern Australia is the oldest basaltic LIP in the Phanerozoic having erupted in the mid Cambrian. At this time, during the Cambrian Explosion, the global environment suffered a series of mass extinctions and biotic turnover. Kalkarindji had the potential to release 1.65 x 106 Tg of CO2, approximately 1.72% of the total Cambrian atmospheric [...]

Global Systematics of Copper in Arc Magmas: A Big Data Approach

Nicholas Dewitt Barber, Marie Edmonds, Frances Jenner, Andreas Audétat, Helen Williams

Published: 2020-10-21
Subjects: Earth Sciences, Geochemistry, Geology, Volcanology

Copper, sourced from porphyry deposits formed in arc settings, is an increasingly scarce yet critical resource. The processes that shape the copper contents of magmas remain poorly understood. One theory is that magmas must be copper-rich in order to form porphyry deposits. Mature arcs have up to now played an outsized role in shaping existing models of copper systematics in magmas. Here we take [...]

The Volcanic & Magmatic Studies Group Equality, Diversity and Inclusion Report 2020

Sally A Gibson, Samantha Engwell, Janine Kavanagh

Published: 2020-07-24
Subjects: Earth Sciences, Education, Physical Sciences and Mathematics, Volcanology

The Volcanic and Magmatic Studies Group (VMSG) takes equality, diversity and inclusion (EDI) seriously and we recognise that the under-representation and/or unconscious marginalisation of any group impacts on our ability to fulfill our mission to serve the volcanology, petrology and geochemistry community. The following report summarises the findings from both the 2016-2020 VMSG annual meetings [...]

Volcanic and Magmatic Studies Group Members Survey 2020

Sally A Gibson, Janine Kavanagh

Published: 2020-07-24
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology

The Volcanic & Magmatic Studies Group (VMSG) is a joint Special Interest Group of the Geological Society of London and Mineralogical Society. In January 2020 we conducted an online questionnaire to establish if (and how) VMSG fulfils its mission to serve the volcanology, petrology and geochemistry community. The survey was distributed via the VMSG mailing list, publicised at the VMSG annual [...]

Rapid heat discharge during deep-sea eruptions generates megaplumes and disperses tephra

Samuel Pegler, David Ferguson

Published: 2020-07-16
Subjects: Earth Sciences, Fluid Dynamics, Geology, Oceanography, Oceanography and Atmospheric Sciences and Meteorology, Other Physical Sciences and Mathematics, Physical Sciences and Mathematics, Physics, Volcanology

Deep-marine volcanism drives Earth’s most energetic transfers of heat and mass between the crust and the oceans. Seafloor magmatic activity has been correlated in time with the appearance of massive enigmatic plumes of hydrothermal fluid, known as megaplumes, yet little is known of the primary source and intensity of the hydrothermal energy release that occurs during [...]

Turbulent flow effects in a slickwater fracture propagation in permeable rock

Evgenii Kanin, Dmitry Garagash, Andrei A. Osiptsov

Published: 2020-06-18
Subjects: Earth Sciences, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Volcanology

This work is devoted to an analysis of the near-tip region of a hydraulic fracture driven by slickwater in a permeable saturated rock. We consider a steady-state problem of a semi-infinite fracture propagating with constant velocity. The host rock is elastic and homogeneous, and fracture propagates according to linear elastic fracture mechanics. The fluid exchange between the fracture and [...]

Deformation controlled Long-Period seismicity in low cohesion volcanic sediments

Pete Rowley, Philip Benson, Christopher Bean

Published: 2020-06-18
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology

Volcano seismicity is an important tool in remotely monitoring and forecasting activity at volcanoes around the world. Volcanic earthquakes show diverse spectral characteristics, with shallow Long Period (Low Frequency) seismicity and long duration tremor generally interpreted as indicators of fluid migration, and as potential precursors to eruption. Here we show that a common low-cohesion [...]

Heat does not physically flow in the ways assumed by greenhouse-warming theory

Peter L Ward

Published: 2020-06-06
Subjects: Climate, Earth Sciences, Oceanography and Atmospheric Sciences and Meteorology, Physical Sciences and Mathematics, Volcanology

Heat is currently defined as an amount of thermal energy flowing each second per unit area. Temperature is assumed to result from the net amount of heat flowing—the sum of all radiative forcings. Yet direct and unambiguous observations of Nature show that macroscopic temperature of solid matter results from a very broad spectrum of sub-microscopic oscillations of all the bonds holding matter [...]

Eruptive dynamics in Plinian silicic eruptions

Sahand Hajimirza, Helge M. Gonnermann, James E. Gardner

Published: 2020-06-04
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology

Plinian eruptions are characterized by high magma discharge rates and pyroclastic material containing extraordinary large numbers of bubbles. Upon ascent to the surface magma decompresses and volatiles become supersaturated, causing bubbles to nucleate with a rate dependent on the degree of supersaturation. Thus, the conventional view is that the number of bubbles nucleating within the erupting [...]

New understanding of hybrid pyroclastic processes revealed from proximal deposits: implications for uncertainty in volcanic hazard assessment

Natasha Joanne Dowey, Rebecca Williams

Published: 2020-05-25
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology

The deposits of Plinian and sub-Plinian eruptions provide critical insights into the behaviour and magnitude of past volcanic events, and inform numerical models that aim to mitigate against future volcanic hazards. However, pyroclastic deposits are often considered from either a fallout or flow perspective, with relatively little attention given to the complex spectrum of hybrid processes that [...]

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