The Dorothy bentonite: an extraordinary case of secondary thickening in a late Campanian volcanic ash fall in central Alberta

2002 ◽  
Vol 39 (12) ◽  
pp. 1745-1754 ◽  
Author(s):  
J F Lerbekmo
Keyword(s):  
British Columbia ◽  
Refractive Index ◽  
Volcanic Ash ◽  
Red Deer ◽  
Silica Content ◽  
River Valley ◽  
Ash Fall ◽  
Isopach Map ◽  
Thickness Measurements ◽  
Glass Shards

The late Campanian (~73 Ma) Dorothy bentonite outcrops in the marine Bearpaw Shale for 20 km along the Red Deer River valley east of Drumheller, Alberta, and is up to 13.5 m thick. An isopach map based upon 230 sub surface and surface thickness measurements illustrates an elongated southwest–northeast lobe with maximum dimensions of about 300 km by 50 km. The volume is ~57 km3 distributed within an area of ~11 000 km2. This bentonite is the altered product of what is believed to be a short-lived Plincan-type eruption from part of the Howell Creek Instrusives in southeastern British Columbia. Fortuitous preservation of the original ash in an up to 2.5 m thick calcite-cemented tuffaceous zone near the middle of the bentonite shows the original ash to have been >99% glass shards and pumice. The remainder of the ash is a crystal component consisting mostly of plagioclase and biotite. The silica content of the isotropic glass shards of about 77%, and a refractive index of 1.503 ± 0.001, suggest a magma of rhyolitic composition.

scholarly journals Landslides in weakly cemented glaciolacustrine sediments, Morkill River valley, British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 889-900 ◽  
Author(s):  
Corey R Froese ◽  
David M Cruden
Keyword(s):  
British Columbia ◽  
River Valley ◽  
Carbonate Content ◽  
Canadian Rocky Mountains ◽  
Density Profiles ◽  
Frost Action ◽  
Dominant Component ◽  
Freeze And Thaw ◽  
Calcite Cement ◽  
The Relationship

Slopes in weakly cemented glaciolacustrine sediments in the Morkill River valley in the Canadian Rocky Mountains stand at up to 70°. Based on field and laboratory observations it appears that a contributing factor to instability is the softening of the soils by frost action and the leaching of calcite cement. Field density profiles demonstrated increased density and carbonate content with an increase in depth. Laboratory tests of carbonate content indicated a positive correlation between calcium carbonate and density in the glaciolacustrine sediments. The relationship was strongest in sands, in which leaching and dissolution were important components of softening. In clays, frost action was the dominant component of softening. Freeze-thaw tests showed a 50% decrease in strength after one cycle of freeze and thaw in the silts and clays.Key words: landslide, cemented, glaciolacustrine sediments, British Columbia.

Simultaneous refractive index and thickness measurements of bio tissue by optical coherence tomography

2002 ◽  
Vol 7 (4) ◽  
pp. 628 ◽  
Author(s):  
Xinyu Wang ◽  
Chunping Zhang ◽  
Lianshun Zhang ◽  
Lingling Xue ◽  
Jianguo Tian
Keyword(s):  
Optical Coherence Tomography ◽  
Refractive Index ◽  
Optical Coherence ◽  
Thickness Measurements

New Lower Jurassic ammonite faunas from the Fernie Formation, southern Canadian Rocky Mountains

1987 ◽  
Vol 24 (8) ◽  
pp. 1688-1704 ◽  
Author(s):  
Russell L. Hall
Keyword(s):  
British Columbia ◽  
North American ◽  
Rocky Mountains ◽  
Red Deer ◽  
First Record ◽  
Lower Jurassic ◽  
Canadian Rocky Mountains ◽  
Poker Chip

New ammonite faunas are described from sections along Bighorn and Scalp creeks in central-western Alberta where Lower Jurassic parts of the Fernie Formation are exposed. The first record of the upper Sinemurian Obtusum Zone from the Fernie is based on the occurrence of Asteroceras cf. stellare and Epophioceras cf. breoni in the basal pebbly coquina on Bighorn Creek. The overlying Red Deer Member has yielded Amaltheus cf. stokesi, representing the upper Pliensbachian Margaritatus Zone; in immediately superjacent strata the first North American examples of ?Amauroceras occur together with Protogrammoceras and ?Aveyroniceras. In the basal parts of the overlying Poker Chip Shale a fauna including Harpoceras cf. falciferum, Harpoceratoides, Polyplectus cf. subplanatus, Hildaites cf. serpentiniformis, and Dactylioceras cf. athleticum is correlated with the lower Toarcian Falciferum Zone.The upper parts of the Poker Chip Shale on Fording River in southeastern British Columbia contain a fauna representing some part of the upper Toarcian, but owing to poor preservation, generic identifications are only tentatively made.

scholarly journals Estimating building vulnerability to volcanic ash fall for insurance and other purposes

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
R. J. Blong ◽  
P. Grasso ◽  
S. F. Jenkins ◽  
C. R. Magill ◽  
T. M. Wilson ◽  
...  
Keyword(s):  
Volcanic Ash ◽  
Building Vulnerability ◽  
Ash Fall

scholarly journals Optical, microphysical and compositional properties of the Eyjafjallajökull volcanic ash

2014 ◽  
Vol 14 (9) ◽  
pp. 13271-13300 ◽  
Author(s):  
A. Rocha-Lima ◽  
J. V. Martins ◽  
L. A. Remer ◽  
N. A. Krotkov ◽  
M. H. Tabacniks ◽  
...  
Keyword(s):  
Refractive Index ◽  
Volcanic Ash ◽  
Fine Particles ◽  
Absorption Efficiency ◽  
Particle Sizes ◽  
Air Volume ◽  
Automatic Software ◽  
Compositional Properties ◽  
Size Distribution Of Particles ◽  
Mass Absorption Efficiency

Abstract. Microphysical, optical, and compositional properties of the volcanic ash from the April–May (2010) Eyjafjallajökull volcanic eruption are presented. Samples of the volcanic ash were taken on the ground in the vicinity of the volcano. The material was sieved, re-suspended, and collected on filters, separating particle sizes into coarse and fine modes. The spectral mass absorption efficiency αabs [m2 g−1] was determined for coarse and fine particles in the wavelength range from 300 to 2500 nm. Size distribution of particles on filters was obtained using a semi-automatic software to analyze images obtained by Scanning Electron Microscopy (SEM). The grain density of the volcanic ash was determined as 2.16(13) g cm−3 by measuring the variation of air volume in a system with volcanic ash and air under compression. Using Mie–Lorenz and T-matrix theories, the imaginary part of the refractive index was derived. Results show the spectral imaginary refractive index ranging from 0.001 to 0.005. Fine and coarse particles were analyzed by X-Ray fluorescence for elemental composition. Fine and coarse mode particles exhibit distinct compositional and optical differences.

scholarly journals Optimal ash particle refractive index model for simulating the brightness temperature spectrum of volcanic ash clouds from satellite infrared sounder measurements

2021 ◽  
Author(s):  
Hiroshi Ishimoto ◽  
Masahiro Hayashi ◽  
Yuzo Mano
Keyword(s):  
Refractive Index ◽  
Brightness Temperature ◽  
Volcanic Ash ◽  
Satellite Measurements ◽  
Temperature Spectrum ◽  
Index Model ◽  
Rock Types ◽  
Volcanic Events ◽  
Atmospheric Sounding ◽  
Using Data

Abstract. Using data from the Infrared Atmospheric Sounding Interferometer (IASI) measurements of volcanic ash clouds and radiative transfer calculations, we identify the optimal refractive index model for simulating the measured brightness temperature spectrum of volcanic ash material. We assume that the optimal refractive index model has the smallest root mean square of the brightness temperature difference between measurements and simulations for channels in the wavenumber range of 750–1400 cm−1 and compare 21 refractive index models for optical properties of ash particles, including recently published models. From the results of numerical simulations for 164 pixels of IASI measurements for ash clouds from 11 volcanoes, we found that the measured brightness temperature spectrum could be well simulated using certain newly established refractive index models. In the cases of Eyjafjallajökull and Grímsvötn ash clouds, the optimal refractive index models determined through numerical simulation correspond to those deduced from the chemical composition of ash samples for the same volcanic eruption events. This finding suggests that infrared sounder measurement of volcanic ash clouds is an effective approach to estimating the optimal refractive index model. However, discrepancies between the estimated refractive index models based on satellite measurements and the associated volcanic rock types were observed for some volcanic events.

Sign in / Sign up

Export Citation Format

Share Document