The formation of circular littoral cones from tube-fed p?hoehoe: Mauna Loa, Hawai'i

Jurado-Chichay, Z.; Rowland, Scott K.; Walker, G. P. L.

doi:10.1007/bf00304433

Cited by 20 publications

(33 citation statements)

References 16 publications

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“…4). The resulting paired half-cone morphology is also common among channel-fed littoral cones (Jurado-Chichay et al 1996;Mattox and Mangan 1997).…”

Section: Aligned Rootless Conesmentioning

confidence: 97%

“…Along coastlines, littoral explosions typically generate radial distributions of tephra with approximately half of the material falling into the sea and the other half constructing crescent-shaped ridges on stable landward surfaces (Fisher 1968;Fisher and Schmincke 1984). Radially symmetric cones can also form in near-coastal environments where tephra is deposited onto stable lava surfaces due to explosive interactions between water-saturated hyaloclastite deltas and overlying lava tubes (Jurado-Chichay et al 1996). If littoral explosions occur in association with lava channels, then tephra may be deposited onto the moving lava surface and rafted to sea, thereby forming paired half-cone deposits on either side of active channels, or paired quarter-cone deposits if the seaward halves of the cones are not preserved (Fisher 1968;Mattox and Mangan 1997).…”

Section: Review Of Previous Researchmentioning

confidence: 99%

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Explosive lava–water interactions I: architecture and emplacement chronology of volcanic rootless cone groups in the 1783–1784 Laki lava flow, Iceland

2010

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To determine the relationships between rootless cone emplacement mechanisms, morphology, and spatial distribution, we mapped the Hnúta and Hrossatungur groups of the 1783-1784 Laki lava flow in Iceland. We based our facies maps on Differential Global Positioning System (DGPS) measurements, photogeological interpretations, and supporting field observations. The study area covers 2.77 km 2 and includes 2216 explosion sites. To establish the timing of rootless cone formation we incorporated tephrochronological constraints from eighty-eight stratigraphic sections and determined that the Hnúta and Hrossatungur groups are composite structures formed by the emplacement of six geographically and chronologically discrete domains. Rootless eruptions initiated in domain 1 on the first day of the Laki eruption (June 8, 1783) and lasted 1-2 days. The second episode of rootless activity began in domain 2 on June 11 and lasted 1-3 days. The four domains of the Hrossatungur group dominantly formed after June 14 and exhibit a complex emplacement sequence that reflects interactions between the Laki lava, contemporaneously emplaced rootless cones, and an existing topographic ridge. In the study area, we identify three distinct rootless cone archetypes (i.e., recurring morphological forms) that are related to tube-, channel-, and broad sheet lobe-fed eruptions. We assert that emplacement of lava above compressible substrates (e.g., unconsolidated sediments) may trigger rootless eruptions by causing subsidence-induced flexure and failure of the basal crust, thereby allowing molten lava (fuel) to come into direct contact with groundwater (coolant) and initiating analogs to explosive molten fuel-coolant interactions (MFCIs).

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“…4). The resulting paired half-cone morphology is also common among channel-fed littoral cones (Jurado-Chichay et al 1996;Mattox and Mangan 1997).…”

Section: Aligned Rootless Conesmentioning

confidence: 97%

Section: Review Of Previous Researchmentioning

confidence: 99%

Explosive lava–water interactions I: architecture and emplacement chronology of volcanic rootless cone groups in the 1783–1784 Laki lava flow, Iceland

2010

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“…In the gap between the crust and the flowing lava the trapped water is heated, and steam blasts and bubbles emanate (Kjargaard 1990). For limu to form, vigorous magma-water intermingling in the surf zone is required (Thordarson and Self 1991;Jurado-Chichay et al 1996). High lava flow rates may result in tephra jets 10s of metres high, formed by the interaction of lava and seawater.…”

Section: Lava Delta and Partial Bench Collapsementioning

confidence: 99%

“…Limu-forming lava is confined to tubes or open channels, with no limu formation observed during advance of pahoehoe tongues over water-saturated sediment at the shoreline, nor during violent, littoral cone-forming seawater interaction with 'a'a lava (Jurado-Chichay et al 1996). Bubble formation sometimes alternates with more violent magma-water interactions, e.g.…”

Section: Initiation and Growth Of Bubblesmentioning

confidence: 99%

The formation of deep-sea Limu o Pele

Maicher

White

2001

Bulletin of Volcanology

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Deep-sea sheet hyaloclastite consists mostly of sand-sized blocky and splinter-shaped shards, but also contains subordinate mm-to cm-sized thin, curved, and wrinkled plates and sheets of sideromelane. This latter type of shard, termed Limu o Pele, has been observed forming subaerially on Kilauea by entrapment of water in flowing lava followed by expansion of steam to form large bubbles which burst into thin fragments. Deepmarine limu has been inferred, from comparative morphological studies and assessment of physical bubbleforming conditions, to form in a similar way but with the increased ambient pressure and the higher viscosity of water reducing bubble expansion. Differing mechanisms of heat transfer and rates of magma chilling also modify the limu-forming process in the deep sea. This paper evaluates a variety of deep-sea limu-forming processes and develops a new and quantitatively supported model, based on observed limu-forming processes and criteria derived from dive samples and observations at Seamount Six, Cocos Plate. It is inferred that water and/or watersaturated sediment was trapped in extremely thin, fluid and rapidly advancing lava flows by various processes. Bubble formation might also occur during small-scale magma-fountaining driven by magmatic volatile exsolution and extreme vent constriction or during collapse of pillows and rapid drainage of the magma, but we found no deposits clearly resulting from these processes.

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“…Volcanic rootless cones (VRCs) are the products of explosive lava-water interactions and are commonly associated with the flow of lava into marshes, lacustrine basins, and littoral environments, as well as over glacial outwash plains, snow, and ice (Thorarinsson 1951(Thorarinsson , 1953Moore and Ault 1965;Fisher 1968;Jurado-Chichay et al 1996;Thordarson et al 1998;Fagents et al 2002;Fagents and Thordarson 2007;Reynolds et al 2015). Terrestrial rootless cone groups cover areas of up to~150 km 2 and generally include numerous cratered cones ranging from 1 to 35 m in height and 2 to 450 m in diameter (Fagents and Thordarson 2007).…”

Section: Introductionmentioning

confidence: 99%

Rootless tephra stratigraphy and emplacement processes

et al. 2017

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Volcanic rootless cones are the products of thermohydraulic explosions involving rapid heat transfer from active lava (fuel) to external sources of water (coolant). Rootless eruptions are attributed to molten fuel-coolant interactions (MFCIs), but previous studies have not performed systematic investigations of rootless tephrostratigraphy and grain-size distributions to establish a baseline for evaluating relationships between environmental factors, MFCI efficiency, fragmentation, and patterns of tephra dispersal. This study examines a 13.55-m-thick vertical section through an archetypal rootless tephra sequence, which includes a rhythmic succession of 28 bed pairs. Each bed pair is interpreted to be the result of a discrete explosion cycle, with fine-grained basal material emplaced dominantly as tephra fall during an energetic opening phase, followed by the deposition of coarsergrained material mainly as ballistic ejecta during a weaker coda phase. Nine additional layers are interleaved throughout the stratigraphy and are interpreted to be dilute pyroclastic density current (PDC) deposits. Overall, the stratigraphy divides into four units: unit 1 contains the largest number of sediment-rich PDC deposits, units 2 and 3 are dominated by a rhythmic succession of bed pairs, and unit 4 includes welded layers. This pattern is consistent with a general decrease in MFCI efficiency due to the depletion of locally available coolant (i.e., groundwater or wet sediments). Changing conduit/ vent geometries, mixing conditions, coolant and melt temperatures, and/or coolant impurities may also have affected MFCI efficiency, but the rhythmic nature of the bed pairs implies a periodic explosion process, which can be explained by temporary increases in the water-to-lava mass ratio during cycles of groundwater recharge.

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The formation of circular littoral cones from tube-fed p?hoehoe: Mauna Loa, Hawai'i

Cited by 20 publications

References 16 publications

Explosive lava–water interactions I: architecture and emplacement chronology of volcanic rootless cone groups in the 1783–1784 Laki lava flow, Iceland

Explosive lava–water interactions I: architecture and emplacement chronology of volcanic rootless cone groups in the 1783–1784 Laki lava flow, Iceland

The formation of deep-sea Limu o Pele

Rootless tephra stratigraphy and emplacement processes

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