Nucleation rates of spherulites in natural rhyolitic lava

2016 ◽  
Vol 101 (11) ◽  
pp. 2367-2376 ◽  
Author(s):  
James E. Gardner ◽  
Kenneth S. Befus ◽  
James M. Watkins ◽  
Travis Clow
Keyword(s):  
Rhyolitic Lava

scholarly journals Facies architecture and origin of a submarine rhyolitic lava flow-dome complex, Ponza, Italy

1998 ◽  
Vol 103 (B11) ◽  
pp. 27551-27566 ◽  
Author(s):  
C. R. Scutter ◽  
R. A. F. Cas ◽  
C. L. Moore ◽  
D. de Rita
Keyword(s):  
Lava Flow ◽  
Facies Architecture ◽  
Rhyolitic Lava

Cristobalite in a rhyolitic lava dome: evolution of ash hazard

2009 ◽  
Vol 72 (2) ◽  
pp. 249-253 ◽  
Author(s):  
Claire J. Horwell ◽  
Jennifer S. Le Blond ◽  
Sabina A. K. Michnowicz ◽  
Gordon Cressey
Keyword(s):  
Lava Dome ◽  
Rhyolitic Lava

scholarly journals Eruption mechanisms and short duration of large rhyolitic lava flows of Yellowstone

2017 ◽  
Vol 458 ◽  
pp. 80-91 ◽  
Author(s):  
Matthew W. Loewen ◽  
Ilya N. Bindeman ◽  
Oleg E. Melnik
Keyword(s):  
Short Duration ◽  
Lava Flows ◽  
Rhyolitic Lava

scholarly journals Microstructure Investigation of Oil-Bearing Rhyolites: A Case Study from the Hailar Basin, NE China

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 699
Author(s):  
Anqi Mao ◽  
Han Zheng ◽  
Xiaomeng Sun
Keyword(s):  
Hydrocarbon Reservoirs ◽  
Hydrocarbon Exploration ◽  
Porous Rocks ◽  
Ne China ◽  
Fluorescence Image ◽  
Crystal Dissolution ◽  
Rhyolitic Lava ◽  
Hailar Basin ◽  
Quantitative Analyses

Understanding the microstructure of rhyolites may greatly promote exploration efforts on rhyolitic hydrocarbon reservoirs; however, related studies are sparse. In this contribution, the microstructure and related porosity of oil-bearing rhyolitic lavas from the Hailar Basin (NE China) were investigated using a combination of optical microscopy, fluorescence image analysis, and scanning electron microscopy. The direct visual and quantitative analyses show that the rhyolites are heterogeneous and porous rocks and have complex microstructures. Phenocryst-rich rhyolitic lava, perlitic lava, and spherulitic rhyolite may be favorable targets for rhyolitic hydrocarbon exploration. For the phenocryst-rich rhyolitic lavas, embayment pores, cleavages, cavitational and shear fractures, and intracrystalline sieve pores are commonly observed in the phenocrysts; while flow-parallel laminar and micropores are ubiquitous in the groundmass. Perlitic lavas are characterized by the occurrence of numerous perlitic fractures which can also be produced in the glassy groundmass of other lavas. Spherulitic rhyolites mainly consist of small-sized (<1 mm) clustered or large-sized (>1 mm) isolated spherulites. Clustered spherulites are characterized by the development of interspherulite pores. Isolated spherulites contain numerous radiating micropores. Both types of spherulites may have water expulsion pores formed in the spherulite–glass border. The formation of the microstructure and related porosity of rhyolites is controlled by pre-, syn- (e.g., deuteric crystal dissolution, cavitation, ductile–brittle deformation, and high-T devitrification), and post-volcanic (e.g., hydration and low-T devitrification) processes. Although pores with diameters > 50 μm are often observed, small pores dominate in pore-size distribution. Small (<15 μm) and large (>300 μm) pores give the most volumetric contribution in most cases. Medium-sized pores with diameters ranging from ~150–300 μm are the least developed and contribute the least to the total volume. The results of this paper can be beneficial to further the understanding of the microstructure and pore system of rhyolites and may be applied to rhyolitic lava hydrocarbon reservoirs elsewhere.

Devitrification of cracked and brecciated Obsidian

1891 ◽  
Vol 9 (44) ◽  
pp. 272-274 ◽  
Author(s):  
Grenville A. J. Cole
Keyword(s):  
Lava Flow ◽  
Royal College ◽  
Convex Surfaces ◽  
Black Glass ◽  
Chilling Effect ◽  
Rhyolitic Lava ◽  
Fractured Surface

In examining a specimen of the rhyolitic lava-flow of the Rocehe Rosse, Lipari, in the collection of the Royal College of Science, London, I was struck by tile fact that the areas of pure black glass visible upon the fractured surface were each bordered by a band of spherulitic matter, the convex surfaces of the spherulites being directed inwards towards tile glassy area. The specimen, collected by Prof. J. W. Judd, F.R.S., evidently comes from a portion of the flow which has become breceiated during movement of the viscid mass; intermingling of glassy and hemicrystalline matter has occurred, and an approach to the structure of the well-known "Piperno" of Naples has resulted. But the irregular little lumps of obsidian have not received their spherulitic crust from any chilling effect that they may have had upon the surrounding groundmass; the spherulites belong to the glass-fragments themselves, and are not deposited upon their surfaces.

The rhyolitic lava flows of the Lebombos (SE-Africa)

1973 ◽  
Vol 37 (4) ◽  
pp. 515-529 ◽  
Author(s):  
H. Wachendorf
Keyword(s):  
Lava Flows ◽  
Rhyolitic Lava
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