scholarly journals Secondary mineral formation in the White River tephra in grassland and forest soils in central Yukon Territory

2005 ◽  
Vol 85 (5) ◽  
pp. 637-648 ◽  
Author(s):  
A. J. Strickland ◽  
J. M. Arocena ◽  
P. Sanborn ◽  
C. A. S. Smith
Keyword(s):  
Forest Soils ◽  
Clay Mineralogy ◽  
Volcanic Glass ◽  
Yukon Territory ◽  
Sand Fraction ◽  
White River ◽  
Mineral Development ◽  
Scanning Electronmicroscopy ◽  
Secondary Mineral Formation ◽  
Rhyolitic Tephra

Selected surface horizons of grassland and forest soils formed under a cold, semi-arid climate were investigated to evaluate the formation of secondary minerals within the White River tephra, a Late Holocene rhyolitic tephra (~115014C yr BP) veneer that overlies the soil landscapes of central Yukon. Concentrations of extractable Fe (< 0.48%), Al (< 0.26%) and Si (< 0.082%) concentrations in surface tephra-contaning horizons of grassland and forest pedons are low. The high amount of exchangeable calcium in grassland soils is likely due to cycling by vegetation and perhaps, aeolian inputs of Ca and Mg carbonates. Al is incorporated into Al-humus complexes in forest pedons and allophane in grassland pedons. Allophane content is low (< 0.56%) in all soils as is ferrihydrite (< 0.34%). Mineral composition of the sand fraction from tephra horizons is dominated by volcanic glass, plagioclase feldspars, amphiboles, epidote, pyroxenes and very limited quantities of quartz and primary Fe oxides. Chlorite and an expanding phyllosilicate were also detected and are assumed to be of detrital origin. Clay mineralogy is dominated by volcanic glass, quartz, feldspars and minimal quantities of kaolinite and dehydrated halloysite in surficial horizons. Kaolinite is assumed to be of detrital origin while dehydrated halloysite is a product of a low leaching and dry environment where limited resilication occurs. Scanning electronmicroscopy (SEM) investigation indicates the presence of opaline silica in surface horizons from forest pedons which has likely formed due to freezing of the soil solution in combination with dehydration and resilication. Overall, the soil horizons formed within the veneer of White River tephra have experienced minimal weathering and very little silicate clay mineral development. Key words: Tephra, glass, Yukon, minerals (secondary), weathering

scholarly journals Pleistocene Geology of the South-West Yukon Territory, Canada

1965 ◽  
Vol 5 (40) ◽  
pp. 385-397 ◽  
Author(s):  
Daniel B. Krinsley
Keyword(s):  
Yukon Territory ◽  
River Valley ◽  
The South ◽  
North West ◽  
White River ◽  
North East ◽  
South West ◽  
M 12

Abstract A morainal sequence in south-west Yukon Territory, Canada, records at least four major, successively less extensive glaciations from ice fields in the St. Elias Mountains south of the glaciated area. The Nisling Moraine flanks the Klondike Plateau in a belt t km. wide to an altitude of 1,040 m., 12 km. north-east of Snag. The northernmost lobe of this moraine terminates at the junction of the Donjek and White Rivers, 120 km, from the nearest source of ice, Klutlan Glacier. 11 km. north-east of Snag, the prominent front of the Donjek Moraine lies 180 m. below the front of the Nisling Moraine. The northernmost lobe of the Donjek Moraine terminates 106 km. north of Klutlan Glacier and occupies the lower courses of canyons cut into the Nisling Moraine. The front of the Snag Moraine crosses the White River valley 210 m. below the front of the Donjek Moraine and 96 km. north of Klutlan Glacier. The Tchawsahmon Moraine, 38 km. north-west of Klutlan Glacier. consists of a series of concentric ridges, the oldest of which impounded Tchawsahmon Lake. Provisional correlations suggest that the Nisling Moraine is pre-Illinoian; the Donjek, Illinoian; the Snag, pre-classical Wisconsin; and the Tchawsahmon, classical Wisconsin.

scholarly journals Pleistocene Geology of the South-West Yukon Territory, Canada

1965 ◽  
Vol 5 (40) ◽  
pp. 385-397 ◽  
Author(s):  
Daniel B. Krinsley
Keyword(s):  
Yukon Territory ◽  
River Valley ◽  
The South ◽  
North West ◽  
White River ◽  
North East ◽  
South West ◽  
M 12

AbstractA morainal sequence in south-west Yukon Territory, Canada, records at least four major, successively less extensive glaciations from ice fields in the St. Elias Mountains south of the glaciated area.The Nisling Moraine flanks the Klondike Plateau in a belt t km. wide to an altitude of 1,040 m., 12 km. north-east of Snag. The northernmost lobe of this moraine terminates at the junction of the Donjek and White Rivers, 120 km, from the nearest source of ice, Klutlan Glacier. 11 km. north-east of Snag, the prominent front of the Donjek Moraine lies 180 m. below the front of the Nisling Moraine. The northernmost lobe of the Donjek Moraine terminates 106 km. north of Klutlan Glacier and occupies the lower courses of canyons cut into the Nisling Moraine. The front of the Snag Moraine crosses the White River valley 210 m. below the front of the Donjek Moraine and 96 km. north of Klutlan Glacier. The Tchawsahmon Moraine, 38 km. north-west of Klutlan Glacier. consists of a series of concentric ridges, the oldest of which impounded Tchawsahmon Lake.Provisional correlations suggest that the Nisling Moraine is pre-Illinoian; the Donjek, Illinoian; the Snag, pre-classical Wisconsin; and the Tchawsahmon, classical Wisconsin.

scholarly journals Discovery of halloysite books in altered silicic Quaternary tephras, northern New Zealand

Clay Minerals ◽  
2016 ◽  
Vol 51 (3) ◽  
pp. 351-372 ◽  
Author(s):  
M.J. Cunningham ◽  
D.J. Lowe ◽  
J.B. Wyatt ◽  
V.G. Moon ◽  
G. Jock Churchman
Keyword(s):  
New Zealand ◽  
Volcanic Glass ◽  
Low Permeability ◽  
Tephra Deposits ◽  
Highly Porous ◽  
Rhyolitic Tephra

AbstractHydrated halloysite was discovered in books, a morphology previously associated exclusively with kaolinite. From ∼1.5 to ∼1500 μm in length, the books showed significantly greater mean Fe contents (Fe2O3= 5.2 wt.%) than tubes (Fe2O3= 3.2 wt.%), and expanded rapidly with formamide. They occurred, along with halloysite tubes, spheroids and plates, in highly porous yet poorly permeable, silt-dominated, Si-rich, pumiceous rhyolitic tephra deposits aged ∼0.93 Ma (Te Puna tephra) and ∼0.27 Ma (Te Ranga tephra) at three sites ∼10–20 m stratigraphically below the modern landsurface in the Tauranga area, eastern North Island, New Zealand. The book-bearing tephras were at or near saturation, but have experienced intermittent partial drying, favouring the proposed changes: solubilized volcanic glass + plagioclase→halloysite spheroids→halloysite tubes→halloysite plates→ halloysite books. Unlike parallel studies elsewhere involving both halloysite and kaolinite, kaolinite has not formed in Tauranga presumably because the low permeability ensures that the sites largely remain locally wet so that the halloysite books are metastable. An implication of the discovery is that some halloysite books in similar settings may have been misidentified previously as kaolinite.

Holocene Glacial and Tree-Line Variations in the White River Valley and Skolai Pass, Alaska and Yukon Territory

1977 ◽  
Vol 7 (1) ◽  
pp. 63-111 ◽  
Author(s):  
George H. Denton ◽  
Wibjörn Karlén
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
Yukon Territory ◽  
Summer Temperature ◽  
River Valley ◽  
Ice Age ◽  
The Arctic ◽  
Tree Line ◽  
White River ◽  
Glacier Recession

Complex glacier and tree-line fluctuations in the White River valley on the northern flank of the St. Elias and Wrangell Mountains in southern Alaska and Yukon Territory are recognized by detailed moraine maps and drift stratigraphy, and are dated by dendrochronology, lichenometry,14C ages, and stratigraphic relations of drift to the eastern (123014C yr BP) and northern (198014C yr BP) lobes of the White River Ash. The results show two major intervals of expansion, one concurrent with the well-known and widespread Little Ice Age and the other dated between 2900 and 210014C yr BP, with a culmination about 2600 and 280014C yr BP. Here, the ages of Little Ice Age moraines suggest fluctuating glacier expansion between ad 1500 and the early 20th century. Much of the 20th century has experienced glacier recession, but probably it would be premature to declare the Little Ice Age over. The complex moraine systems of the older expansion interval lie immediately downvalley from Little Ice Age moraines, suggesting that the two expansion intervals represent similar events in the Holocene, and hence that the Little Ice Age is not unique. Another very short-lived advance occurred about 1230 to 105014C yr BP. Spruce immigrated into the valley to a minimum altitude of 3500 ft (1067 m), about 600 ft (183 m) below the current spruce tree line of 4100 ft (1250 m), at least by 802014C yr BP. Subsequent intervals of high tree line were in accord with glacier recession; in fact, several spruce-wood deposits above current tree line occur bedded between Holocene tills. High deposits of fossil wood range up to 76 m above present tree line and are dated at about 5250, 3600 to 3000, and 2100 to 123014C yr BP. St. Elias glacial and tree-line fluctuations, which probably are controlled predominantly by summer temperature and by length of the growing and ablation seasons, correlate closely with a detailed Holocene tree-ring curve from California, suggesting a degree of synchronism of Holocene summer-temperature changes between the two areas. This synchronism is strengthened by comparison with the glacier record from British Columbia and Mt. Rainier. Likewise, broad synchronism of Holocene events exists across the Arctic between the St. Elias Mountains and Swedish Lappland. Finally, two sequences from the Southern Hemisphere show similar records, in so far as dating allows. Hence, we believe that a preliminary case can be made for broad synchronism of Holocene climatic fluctuations in several regions, although further data are needed and several areas, particularly Colorado and Baffin Island, show major differences in the regional pattern.

A two-stage model for the formation of clay minerals from tephra-derived volcanic glass

Clay Minerals ◽  
1990 ◽  
Vol 25 (3) ◽  
pp. 313-327 ◽  
Author(s):  
A. P. W. Hodder ◽  
B. E. Green ◽  
D. J. Lowe
Keyword(s):  
Clay Minerals ◽  
Late Quaternary ◽  
Volcanic Glass ◽  
Chemical Processes ◽  
Diffusion Controlled ◽  
Tephra Layers ◽  
Clay Formation ◽  
Kinetics Of ◽  
Calculated Activation ◽  
Rhyolitic Tephra

AbstractThe kinetics of clay formation in buried paleosols developed from late Quaternary rhyolitic tephra layers near Rotorua, New Zealand, can be described in terms of a combination of parabolic and linear kinetics, reflecting the hydration of glass, and the formation of clay minerals, respectively. Such a model is consistent with the formation of clay minerals showing an Arrhenian temperature dependence and suggests, on the basis of calculated activation energies, that the process of formation of Al-rich allophane (imogolite) is diffusion controlled, whereas the rate of formation of Si-rich allophane is controlled by the chemical processes at the site of reaction.

The White River Ash: largest Holocene Plinian tephra

2008 ◽  
Vol 45 (6) ◽  
pp. 693-700 ◽  
Author(s):  
J. F. Lerbekmo
Keyword(s):  
Grain Size ◽  
Far East ◽  
Yukon Territory ◽  
Square Root ◽  
Eruption Rate ◽  
Present Evidence ◽  
White River ◽  
The North ◽  
Bear Lake ◽  
Straight Line

The White River Ash is a bi-lobate tephra in eastern Alaska, Yukon Territory, and western Northwest Territories. Plinian-type eruptions produced the north lobe ∼1900 years BP and the larger east lobe ∼1250 years BP (14C years). Present evidence favors the vent for the east lobe to be beneath the Klutlan Glacier. East lobe pumice is not present atop Mt. Churchill, so the pumice there must belong to the north lobe and is also likely to have come from a vent beneath the Klutlan Glacier. Isopachs of the east lobe, now known to stretch as far east as Great Bear Lake, indicate an east lobe volume of ∼47 km3. Thickness and grain size of the east lobe decay in exponential fashion, producing straight line plots when the thickness half-distance and clast half-distance are plotted against the square root of the isopach area, the proximal slope being steeper than the distal. The east lobe eruption is indicated to have been into a wind of about 10 m/s and to have produced an eruptive cloud height of ∼45 km. The eruption rate was at least 2.8 × 108 kg/s.

Halloysite in late pleistocene rhyolitic tephra beds near Opotiki, coastal Bay of Plenty, North Island, New Zealand

Soil Research ◽  
1978 ◽  
Vol 16 (1) ◽  
pp. 1 ◽  
Author(s):  
JH Kirkman ◽  
WA Pullar
Keyword(s):  
New Zealand ◽  
Late Pleistocene ◽  
Clay Mineralogy ◽  
Time Period ◽  
Cylindrical Form ◽  
Long Time ◽  
Coastal Bay ◽  
Tephra Beds ◽  
Rhyolitic Tephra

Investigation of the clay mineralogy of 14 rhyolitic tephra beds with a suggested age of 125000 to 220000 years revealed that the squat cylindrical form of halloysite is the dominant crystalline mineral. This mineral has probably crystallized from allophane over a long time period, excess silica being precipitated as a weakly hydrated phase. The squat cylindrical crystals perhaps characterize halloysite formation in rhyolitic tephras.

Distribution, composition, and source of the White River Ash, Yukon Territory

1969 ◽  
Vol 6 (1) ◽  
pp. 109-116 ◽  
Author(s):  
J. F. Lerbekmo ◽  
F. A. Campbell
Keyword(s):  
Chemical Composition ◽  
Yukon Territory ◽  
Aerial Photographs ◽  
Average Chemical Composition ◽  
Large White ◽  
X Ray ◽  
White River ◽  
Significant Difference ◽  
Target Source ◽  
Distribution Composition

The White River Ash is a bi-lobate 1500 year old deposit occupying at least 6 cubic miles and covering some 125 000 square miles of southern Yukon and eastern Alaska. Sixty-six samples were collected at 5-mile intervals, principally along two traverses 120 miles apart across the main lobe, and subjected to X-ray fluorescence and petrographic analysis.The ash is a rhyodacite composed of glass (n = 1.502), andesine, hornblende, hypersthene, and magnetite. The average chemical composition is SiO2 = 67.4, Al2O3 = 15.1, TiO2 = 0.5, MgO = 2.0, FeO = 2.0, Fe2O3 = 2.2, Na2O = 4.1, K2O = 2.5 and CaO = 4.1, but there is a significant difference between the two traverses owing to the increase in glass relative to crystal components downwind.A synthesis of the distribution of the ash permitted the drawing of a 5 by 12 miles 'target' source rectangle in the St. Elias Range between Mts. Natazhat and Bona in Alaska. Aerial photographs revealed a suspect mound 0.4 miles in diameter beside the Klutlan Glacier. Access by helicopter showed the mound to be a flat cone of large White River pumice fragments. It is believed that the vent lies beneath the glacier next to the cone.

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