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.

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.

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.

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 Period-Life of a Branching Process with Migration and Continuous Time

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 868
Author(s):  
Khrystyna Prysyazhnyk ◽  
Iryna Bazylevych ◽  
Ludmila Mitkova ◽  
Iryna Ivanochko
Keyword(s):  
Random Process ◽  
Generating Function ◽  
Continuous Time ◽  
Branching Process ◽  
Probability Generating Function ◽  
Time Interval ◽  
The Moment ◽  
First Time ◽  
Critical Branching Process ◽  
Number Of Particles

The homogeneous branching process with migration and continuous time is considered. We investigated the distribution of the period-life τ, i.e., the length of the time interval between the moment when the process is initiated by a positive number of particles and the moment when there are no individuals in the population for the first time. The probability generating function of the random process, which describes the behavior of the process within the period-life, was obtained. The boundary theorem for the period-life of the subcritical or critical branching process with migration was found.

Pleistocene Mammals from Gold Run Creek, Yukon Territory

1973 ◽  
Vol 10 (5) ◽  
pp. 697-759 ◽  
Author(s):  
C. R. Harington ◽  
F. V. Clulow
Keyword(s):  
Yukon Territory ◽  
Radiocarbon Date ◽  
Common Elements ◽  
Radiocarbon Dates ◽  
Equus Asinus ◽  
Wild Ass ◽  
Pleistocene Mammals ◽  
First Time

Remains of thirteen species of mammals are reported from Pleistocene deposits at Gold Run Creek near Dawson, Yukon Territory. Eight of the thirteen species are extinct and two are no longer living in the Yukon. The most common elements of the fauna are Equus (Asinus) lambei (Yukon wild ass), and Bison crassicornis (large-horned bison). Taxidea (badger) and Bison alaskensis (Alaskan bison) are reported for the first time from the Yukon Pleistocene. A kiang-like horse is also reported from deposits at Gold Run Creek.These mammals may have inhabited a cool grassland or open parkland during late Wisconsin time. Bison crassicornis and mammoth bone from deposits at Gold Run Creek have yielded radiocarbon dates of 22 200 ± 1400 yr B.P. and 32 250 ± 1750 yr B.P. respectively. Bison alaskensis is evidently older than the remainder of the fauna as bone from the specimen yielded a radiocarbon date of over 39 900 yr B.P.

New Complexities in Zoogeography and Taxonomy of the Pygmy Whitefish (Prosopium coulteri)

1972 ◽  
Vol 29 (12) ◽  
pp. 1772-1775 ◽  
Author(s):  
C. C. Lindsey ◽  
W. G. Franzin
Keyword(s):  
River System ◽  
Yukon Territory ◽  
Hudson Bay ◽  
The South ◽  
Bristol Bay ◽  
River Drainage ◽  
Bay Area ◽  
First Time ◽  
Mackenzie River

Pygmy whitefish (Prosopium coulteri) are recorded for the first time from the Peel–Mackenzie river drainage (Elliott Lake, Yukon Territory) and from the Hudson Bay drainage (Waterton Lakes, Alberta, in the South Saskatchewan–Nelson river system). The morphology of specimens from both localities contradicts the previously known pattern of a southeastern "low-rakered" and a northwestern "high-rakered" form (with the two forms occurring sympatrically in some lakes of the Bristol Bay area). Specimens from Elliott Lake, the most northerly known locality, resemble the southeastern form and those from Waterton Lakes the northwestern form. Both Waterton and Elliott lakes lie close to unglaciated refugia, suggesting that the species may have survived Wisconsin glaciation and diverged in several different watersheds.

The sequence and correlation of Early Ordovician (Arenig) graptolite faunas in the Richardson Trough and Misty Creek Embayment, Yukon Territory and District of Mackenzie, Canada

2006 ◽  
Vol 43 (12) ◽  
pp. 1791-1820 ◽  
Author(s):  
D E Jackson ◽  
A C Lenz
Keyword(s):  
Northwest Territories ◽  
Deep Water ◽  
Yukon Territory ◽  
Early Ordovician ◽  
The Road ◽  
Bedded Chert ◽  
First Occurrence ◽  
Mackenzie Mountains ◽  
First Time

Four graptolite biozones are recorded from the Arenig portion of the Road River Group in the Richardson and Mackenzie mountains in the Yukon and Northwest Territories. In ascending order, these zones are Tetragraptus approximatus, Pendeograptus fruticosus, Didymograptus bifidus, and Parisograptus caduceus australis (new). The Castlemainian stage may be represented by nongraptolitic massive bedded chert. The Arenig–Llanvirn boundary is drawn below the first occurrence of Undulograptus austrodentatus. Fifty-four graptolite taxa are present, and 16 of these species and subspecies are recorded for the first time in this deep-water biotope, namely, Didymograptus? cf. adamantinus, D. asperus, D. dilatans, D. cf. kurcki, D. validus communis, Holmograptus aff. leptograptoides, H. sp. A, Isograptus? sp. nov. A, I. ? dilemma, Keblograptus geminus, Pseudisograptus manubriatus harrisi, Ps. m. koi, Ps. m. janus, Ps. cf. tau, Xiphograptus lofuensis, and Zygograptus cf. abnormis.

Late Cenozoic uplift of western Turkey: Improved dating of the Kula Quaternary volcanic field and numerical modelling of the Gediz River terrace staircase

2006 ◽  
Vol 51 (3-4) ◽  
pp. 131-171 ◽  
Author(s):  
Rob Westaway ◽  
Hervé Guillou ◽  
Sema Yurtmen ◽  
Anthony Beck ◽  
David Bridgland ◽  
...  
Keyword(s):  
Numerical Modelling ◽  
Volcanic Field ◽  
River Terrace ◽  
Late Cenozoic ◽  
Western Turkey ◽  
Gediz River

Emmons Lake Volcanic Center, Alaska Peninsula: source of the Late Wisconsin Dawson tephra, Yukon Territory, Canada

2003 ◽  
Vol 40 (7) ◽  
pp. 925-936 ◽  
Author(s):  
Margaret T Mangan ◽  
Christopher F Waythomas ◽  
Thomas P Miller ◽  
Frank A Trusdell
Keyword(s):  
Compositional Data ◽  
Late Quaternary ◽  
Yukon Territory ◽  
Volcanic Center ◽  
Pyroclastic Deposits ◽  
Alaska Peninsula ◽  
Aleutian Arc ◽  
Pumice Flow ◽  
North And South ◽  
The Bering Sea

The Emmons Lake Volcanic Center on the Alaska Peninsula of southwestern Alaska is the site of at least two rhyolitic caldera-forming eruptions (C1 and C2) of late Quaternary age that are possibly the largest of the numerous caldera-forming eruptions known in the Aleutian arc. The deposits produced by these eruptions are widespread (eruptive volumes of >50 km3 each), and their association with Quaternary glacial and eolian deposits on the Alaska Peninsula and elsewhere in Alaska and northwestern Canada enhances the likelihood of establishing geochronological control on Quaternary stratigraphic records in this region. The pyroclastic deposits associated with the second caldera-forming eruption (C2) consist of loose, granular, airfall and pumice-flow deposits that extend for tens of kilometres beyond Emmons Lake caldera, reaching both the Bering Sea and Pacific Ocean coastlines north and south of the caldera. Geochronological and compositional data on C2 deposits indicate a correlation with the Dawson tephra, a 24 000 14C BP (27 000 calibrated years BP), widespread bed of silicic ash found in loess deposits in west-central Yukon Territory, Canada. The correlation clearly establishes the Dawson tephra as the time-stratigraphic marker of the last glacial maximum.

Geochemical constraints on the origin of late Cenozoic basalts in the Mt. Changbai volcanic field, NE China: evidence for crustal recycling

2019 ◽  
Vol 62 (17) ◽  
pp. 2125-2145 ◽  
Author(s):  
Ming Lei ◽  
Zhengfu Guo ◽  
Yutao Sun ◽  
Maoliang Zhang ◽  
Lihong Zhang ◽  
...  
Keyword(s):  
Volcanic Field ◽  
Late Cenozoic ◽  
Ne China ◽  
Crustal Recycling ◽  
Geochemical Constraints
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