A catalogue of late Cenozoic tephra beds in the Klondike goldfields and adjacent areas, Yukon Territory1Yukon Geological Survey Contribution 010.

2011 ◽  
Vol 48 (10) ◽  
pp. 1386-1418 ◽  
Author(s):  
S.J. Preece ◽  
J.A. Westgate ◽  
D.G. Froese ◽  
N.J.G. Pearce ◽  
W.T. Perkins
Keyword(s):  
Volcanic Field ◽  
Trace Element Composition ◽  
Element Composition ◽  
Yukon Territory ◽  
Late Cenozoic ◽  
Major Element Composition ◽  
Aleutian Arc ◽  
Tephra Beds ◽  
Cenozoic Sediments ◽  
Distinguishing Features

Many distal tephra beds exist in the late Cenozoic sediments of the Klondike goldfields and nearby areas. They come from volcanoes in the Wrangell volcanic field and the eastern Aleutian arc and represent large-magnitude eruptions. During the course of our tephrochronological studies in this region over the last 40 years, we have discovered 196 tephra occurrences and 50 distinctive tephra beds. The location of these sites and the distinguishing features of each of these tephra beds are presented in the form of a catalogue, which we hope will provide a stimulus for present and future tephrochronological studies in the Yukon Territory. These data are presented as a series of tables, as follows: location, stratigraphic context, petrography, geochemical characteristics, including major- and trace-element composition of glass shards, major-element composition of Fe–Ti oxides, classification, and age determinations. A new classification scheme is presented in which the rhyolitic and dacitic tephra beds are grouped into three classes: adakite, transitional, and typical arc.

Characterization, identity, distribution, and source of late Cenozoic tephra beds in the Klondike district of the Yukon, Canada

2000 ◽  
Vol 37 (7) ◽  
pp. 983-996 ◽  
Author(s):  
Shari J Preece ◽  
John A Westgate ◽  
Brent V Alloway ◽  
Michael W Milner
Keyword(s):  
Volcanic Field ◽  
Yukon Territory ◽  
Time Interval ◽  
Late Cenozoic ◽  
Stratigraphic Framework ◽  
Aleutian Arc ◽  
High Silica ◽  
Late Wisconsinan ◽  
Tephra Beds ◽  
First Time

A large number of distal, silicic tephra beds have been preserved in the late Cenozoic deposits of the Klondike region, Yukon Territory. Forty-one tephra samples, representing twelve distinctive beds, are detailed in this study. They range in composition from basaltic andesite to high-silica rhyolite, and were deposited during the late Pliocene to Late Wisconsinan time interval. Seven tephra beds are derived from volcanoes in the Wrangell volcanic field, and four come from the more distant eastern Aleutian arc - Alaska Peninsula region, but the source of the single andesitic tephra is unknown. The widespread and well known Old Crow and Sheep Creek tephra beds have been identified in the Klondike district, but all the other tephra units are characterized in detail for the first time. The ages of most tephra beds are poorly constrained, but will undoubtedly become better known with the application of recently developed glass fission-track methods. Hence, prospects are favourable for the eventual development of a comprehensive and reliable time-stratigraphic framework that will support on-going studies on the late Cenozoic geology, geomorphology, paleontology, and paleoenvironments of the Klondike area.

Dating Early and Middle (Reid) Pleistocene Glaciations in Central Yukon by Tephrochronology

2001 ◽  
Vol 56 (3) ◽  
pp. 335-348 ◽  
Author(s):  
John A. Westgate ◽  
Shari J. Preece ◽  
Duane G. Froese ◽  
Robert C. Walter ◽  
Amanjit S. Sandhu ◽  
...  
Keyword(s):  
Gulf Of Alaska ◽  
Supporting Evidence ◽  
Pleistocene Glaciations ◽  
Late Cenozoic ◽  
Aeolian Sand ◽  
Oxygen Isotope Stage ◽  
Aleutian Arc ◽  
Dawson City ◽  
Cordilleran Ice Sheet ◽  
Tephra Beds

AbstractThe late Cenozoic deposits of central Yukon contain numerous distal tephra beds, derived from vents in the Wrangell Mountains and Aleutian arc–Alaska Peninsula region. We use a few of these tephra beds to gain a better understanding on the timing of extensive Pleistocene glaciations that affected this area. Exposures at Fort Selkirk show that the Cordilleran Ice Sheet advanced close to the outer limit of glaciation about 1.5 myr ago. At the Midnight Dome Terrace, near Dawson City, exposed outwash gravel, aeolian sand, and loess, related to valley glaciers in the adjacent Ogilvie Mountains, are of the same age. Reid glacial deposits at Ash Bend on the Stewart River are older than oxygen isotope stage (OIS) 6 and likely of OIS 8 age, that is, about 250,000 yr B.P. Supporting evidence for this chronology comes from major peaks in the rates of terrigeneous sediment input into the Gulf of Alaska at 1.5 and 0.25 myr B.P.

scholarly journals Lake Ohrid’s tephrochronological dataset reveals 1.36 Ma of Mediterranean explosive volcanic activity

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Niklas Leicher ◽  
Biagio Giaccio ◽  
Giovanni Zanchetta ◽  
Roberto Sulpizio ◽  
Paul G. Albert ◽  
...  
Keyword(s):  
Volcanic Activity ◽  
Inductively Coupled Plasma ◽  
Trace Element Composition ◽  
Element Composition ◽  
Lake Ohrid ◽  
Central Mediterranean ◽  
Major Element Composition ◽  
Wavelength Dispersive Spectroscopy ◽  
Geochemical Fingerprint ◽  
Tephra Layers

AbstractTephrochronology relies on the availability of the stratigraphical, geochemical and geochronological datasets of volcanic deposits, three preconditions which are both often only fragmentary accessible. This study presents the tephrochronological dataset from the Lake Ohrid (Balkans) sediment succession continuously reaching back to 1.36 Ma. 57 tephra layers were investigated for their morphological appearance, geochemical fingerprint, and (chrono-)stratigraphic position. Glass fragments of tephra layers were analyzed for their major element composition using Energy-Dispersive-Spectroscopy and Wavelength-Dispersive Spectroscopy and for their trace element composition by Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. Radiometric dated equivalents of 16 tephra layers and orbital tuning of geochemical proxy data provided the basis for the age-depth model of the Lake Ohrid sediment succession. The age-depth model, in turn, provides ages for unknown or undated tephra layers. This dataset forms the basis for a regional stratigraphic framework and provides insights into the central Mediterranean explosive volcanic activity during the last 1.36 Ma.

scholarly journals Quaternary tephra from the Valles caldera in the volcanic field of the Jemez Mountains of New Mexico identified in western Canada

2018 ◽  
Vol 91 (2) ◽  
pp. 813-828 ◽  
Author(s):  
John A. Westgate ◽  
Giday WoldeGabriel ◽  
Henry C. Halls ◽  
Colin J. Bray ◽  
René W. Barendregt ◽  
...  
Keyword(s):  
New Mexico ◽  
Volcanic Field ◽  
Trace Element Composition ◽  
Early Pleistocene ◽  
Valles Caldera ◽  
Fine Grained ◽  
Jemez Mountains ◽  
Bandelier Tuff ◽  
Tephra Beds

AbstractA fine-grained, up to 3-m-thick tephra bed in southwestern Saskatchewan, herein named Duncairn tephra (Dt), is derived from an early Pleistocene eruption in the Jemez Mountains volcanic field of New Mexico, requiring a trajectory of northward tephra dispersal of ~1500 km. An unusually low CaO content in its glass shards denies a source in the closer Yellowstone and Heise volcanic fields, whereas a Pleistocene tephra bed (LSMt) in the La Sal Mountains of Utah has a very similar glass chemistry to that of the Dt, supporting a more southerly source. Comprehensive characterization of these two distal tephra beds along with samples collected near the Valles caldera in New Mexico, including grain size, mineral assemblage, major- and trace-element composition of glass and minerals, paleomagnetism, and fission-track dating, justify this correlation. Two glass populations each exist in the Dt and LSMt. The proximal correlative of Dt1 is the plinian Tsankawi Pumice and co-ignimbritic ash of the first ignimbrite (Qbt1g) of the 1.24 Ma Tshirege Member of the Bandelier Tuff. The correlative of Dt2 and LSMt is the co-ignimbritic ash of Qbt2. Mixing of Dt1 and Dt2 probably occurred during northward transport in a jet stream.

Fission-track ages of late Cenozoic distal tephra beds in the Yukon Territory and Alaska

1982 ◽  
Vol 19 (11) ◽  
pp. 2167-2178 ◽  
Author(s):  
Nancy D. Naeser ◽  
John A. Westgate ◽  
Owen L. Hughes ◽  
Troy L. Péwé
Keyword(s):  
Fission Track ◽  
Yukon Territory ◽  
Late Cenozoic ◽  
Geologic History ◽  
Detailed Characterization ◽  
Track Method ◽  
History Of ◽  
Characterization Studies ◽  
Fission Track Ages ◽  
Tephra Beds

Six distal tephra beds from the Yukon Territory and Alaska have been dated by the fission-track method. Zircon and glass ages were determined for the Fort Selkirk and Lost Chicken tephra beds, but only glass ages for the others.Assuming that no track fading has occurred in the glass, Old Crow and Dawson tephra beds are younger than 120 000 and 52 000 years BP, respectively. Mosquito Gulch tephra is 1.22 Ma old, Fort Selkirk tephra is about 1 Ma old, the Ester Ash Bed is 0.45 Ma old, and the best estimate of the age of Lost Chicken tephra is the range 1.7–2.6 Ma.It is evident from these results and from the known abundance of tephra beds within late Cenozoic deposits of the Yukon Territory and Alaska that application of the fission-track method to distal tephra, in conjunction with detailed characterization studies, offers great potential for elucidation of the late Cenozoic geologic history of Alaska and the Yukon Territory.

scholarly journals Influence Of The Large Flood On The Element Composition Of Fluvisols In The Amur River Valley

2020 ◽  
Vol 13 (2) ◽  
pp. 52-64
Author(s):  
Alexander V. Martynov
Keyword(s):  
Trace Elements ◽  
Global Climate ◽  
Management Strategies ◽  
Total Content ◽  
Major Elements ◽  
Trace Element Composition ◽  
Element Composition ◽  
Major Element Composition ◽  
The Impact ◽  
Main Factor

Floodplain soils function as long-lasting stock or source of different substances, including pollutants. The main factor determining biochemical processes in fluvisols is flooding. Global climate change, which is causing more frequent and massive floods, is urging us to assess the potential environmental risks and create appropriate environmental management strategies. This study was performed to estimate the impact of a heavy flood on the total content of major elements and both total and mobile trace elements in fluvisols of one of the longest rivers in the world, the Amur. The study was conducted in field conditions by sampling from the same soil profiles before and after the flood. As a result, 10 major and 42 trace elements were distinguished. Major-element composition was determined with X-ray fluorescent method, trace-element composition - with the inductive coupled plasma mass spectroscopy. Maximum decrease of concentration was determined for CaO, MnO, P2O5 (up to 60%) and Sr, Cd, Ba, Tl and Pb (up to 40%). Significant increase was in concentration of Ni, Cu, and Mo (up to 160%). Among mobile trace elements, increase was observed in concentration of Sc, Ni and Th (up to 400%). With the correlation analysis, it was also established that the main causes of changes in elemental composition of the soils were decrease of pH, development of redox environment and washing out of organic matter. The main factor determining the influence of the flood on fluvisols was floodplain relief, which affected the length of the inundation, flood water velocity and the way allochthonic matter retained.

Major- and trace-element characterization, expanded distribution, and a new chronology for the latest Pleistocene Glacier Peak tephras in western North America

2009 ◽  
Vol 71 (2) ◽  
pp. 201-216 ◽  
Author(s):  
Stephen C. Kuehn ◽  
Duane G. Froese ◽  
Paul E. Carrara ◽  
Franklin F. Foit ◽  
Nicholas J.G. Pearce ◽  
...  
Keyword(s):  
North America ◽  
Trace Element ◽  
Late Pleistocene ◽  
Major Element ◽  
Element Composition ◽  
Western North America ◽  
Major Element Composition ◽  
Element Abundances ◽  
Southern Alberta ◽  
Tephra Beds

AbstractThe Glacier Peak tephra beds are among the most widespread and arguably some of the most important late Pleistocene chronostratigraphic markers in western North America. These beds represent a series of closely-spaced Plinian and sub-Plinian eruptions from Glacier Peak, Washington. The two most widespread beds, Glacier Peak ‘G’ and ‘B’, are reliably distinguished by their glass major and trace element abundances. These beds are also more broadly distributed than previously considered, covering at least 550,000 and 260,000 km2, respectively. A third bed, the Irvine bed, known only from southern Alberta, is similar in its major-element composition to the Glacier Peak G bed, but it shows considerable differences in trace element concentrations. The Irvine bed is likely considerably older than the G and B tephras and probably records an additional Plinian eruption, perhaps also from Glacier Peak but from a different magma than G through B. A review of the published radiocarbon ages, new ages in this study, and consideration in a Bayesian framework suggest that the widespread G and B beds are several hundred years older than widely assumed. Our revised age is about 11,600 14C yr BP or a calibrated age (at 2 sigma) of 13,710–13,410 cal yr BP.

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