Volcanic Centers of the Sunlight Area Park County, Wyoming

Parsons, Willard H.

doi:10.1086/624734

Cited by 18 publications

(6 citation statements)

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“…The basic shape of a radial dike is a thin blade, with the long axis horizontal and the intermediate axis vertical. A blade shape in this orientation is well documented for radial dikes elsewhere (parsons 1939;Fiske & Jackson 1972;Sanderson 1982). At the highest level now preserved, Lyttelton dikes generally thicken upwards, though it must be that dikes thinned upwards in central areas beneath the now eroded volcano summit (see below and progressively through the dikelflow or dome interface (see below).…”

Section: Shape Of Dikesmentioning

confidence: 75%

“…6) show a 180 0 range of flow directions, more or less evenly balanced between upwards and downwards, but with the vast majority in an outwards horizontal direction. Parsons (1939) and Smith (1978) have described essentially horizontal flow directions for ancient radial dikes in the U.S., and flow in the active Hawaiian and Etnaean radial dikes is also deduced to be mainly horizontal (Fiske & Jackson 1972;Sanderson et al 1983). It is likely that dike fractures propagate progressively by wedging outwards, downwards, and upwards (Fig.…”

Section: Flow Directions In the Dikesmentioning

confidence: 94%

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Radial dikes of Lyttelton Volcano — their structure, form, and petrography

Shelley

1988

New Zealand Journal of Geology and Geophysics

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Radial dikes of Lyttelton Volcano, Banks Peninsula, New Zealand, are mainly hawaiite, with basalt, mugearite, and trachyte next in abundance. Spatial distribution of compositional types is not regular, one interpretation being that the proportion of trachyte increased with time. Analysis of dike numbers suggests there were 2000 near the volcanic centre, and <500 at the level of the eroded crater rim. Dikes have a blade shape with the long axis horizontal. Flow directions are dominantly along that axis with significant deviations up to 90° either side. Dike traces are marked by bends and offsets of as much as 125 m. Most dikes are <1.5 m thick, but they range up to 20 m. Thickness changes slowly horizontally outwards, but quickly vertically; many dikes thicken upwards to the point where they feed flows and domes, or have been cut off by penecontemporaneous erosion. Dikes played a major role in the construction of the volcano, probably a continuous role. A modem analogue is Etna.

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Section: Shape Of Dikesmentioning

confidence: 75%

Section: Flow Directions In the Dikesmentioning

confidence: 94%

Radial dikes of Lyttelton Volcano — their structure, form, and petrography

Shelley

1988

New Zealand Journal of Geology and Geophysics

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“…A similar model has been proposed for the Sunlight volcanic center, an eroded stratovolcano in northwest Wyoming. Based on outcrop configurations and cross cutting relationships, Parsons (1939) speculated that magma flow in radial dikes at Sunlight volcano was steeply inclined within ∼800 m of the center of the volcano, but became subhorizontal towards the flanks of the edifice with increasing radial distance.…”

Section: Preferred Model For Radial Dike Intrusionmentioning

confidence: 99%

“…Our model, however, is based primarily on a detailed study of one eroded stratovolcano, and should be tested at other locations. Eroded volcanoes with exposed radial dike swarms that may be targeted for additional work include West Elk Peak in central Colorado (Gaskill et al 1981), Mount Taylor in central New Mexico (Lipman et al 1979), Sunlight volcano in western Wyoming (Parsons 1939), and San Francisco Mountain in northern Arizona (Holm 1988). If it proves accurate for other volcanic centers, the model presented in this paper could be used in support of hazards assessments of active composite volcanoes.…”

Section: Conclusion and Suggestions For Future Workmentioning

confidence: 99%

A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA

Poland

Moats²,

Fink

2007

Bull Volcanol

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“…GCRG is inferred to consist of a debris mantle overlying ice or a debris-ice mixture that, in turn, overlies bedrock. The source rocks for the debris cover on GCRG are predominantly Tertiary volcanic rocks (Parsons 1937(Parsons , 1939. Significant contrasts in seismic wave velocity might be expected given the varying composition of these materials.…”

Section: New Seismic Refraction Surveys Of Gcrgmentioning

confidence: 99%

Galena creek rock glacier revisited—new observations on an old controversy

Potter

Steig

Clark

et al. 1998

Geografiska Annaler: Series A, Physical Geography

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Galena Creek rock glacier (GCRG), northwest Wyoming, exhibits most of the classic characteristics of rock glaciers. Clean ice with silty bands was found beneath a c. 1 m thick debris mantle by Potter. He inferred that the ice is glacigenic, originating in the small snowfield in the cirque at the head of GCRG. This view was challenged by Barsch, who asserted that the ice in GCRG is of "permafrost" origin. Since then GCRG has become a lightning rod for opponents and proponents of the glacigenic ice model for rock glaciers. We review evidence for that model here.Movement marks emplaced on GCRG in the 1960s were resurveyed in 1995 for a 30+ year record of movement. Maximum surface velocity is 45 cm/yr on gentle slopes and 80 cm/yr in a steep reach where GCRG spills out of the cirque. The less active, downvalley third of GCRG is moving at a maximum 14 cm/yr, and lobes formed between the more and less active parts have complex movement and are advancing down-valley over adjacent lobes at a maximum of 6.5 cm/yr. New refraction seismic profiles on GCRG were used to determine the thickness of the debris mantle over ice. On the up-valley, active part of GCRG, the debris mantle is a relatively uniform c. 1 m thick. On the down-valley, less active part, the thickness of the debris mantle is much more variable, but it is generally thicker. We cannot tell, on the basis of seismic data alone, whether the frozen material beneath the debris mantle is ice or a debris-ice mixture, but the results are not inconsistent with the glacigenic model for the origin of the ice. Two long-profiles in the cirque may identify bedrock at about 20-25 m depth.

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Volcanic Centers of the Sunlight Area Park County, Wyoming

Cited by 18 publications

References 0 publications

Radial dikes of Lyttelton Volcano — their structure, form, and petrography

Radial dikes of Lyttelton Volcano — their structure, form, and petrography

A model for radial dike emplacement in composite cones based on observations from Summer Coon volcano, Colorado, USA

Galena creek rock glacier revisited—new observations on an old controversy

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