Stratigraphic, isotopic, and mineralogical evidence for an early Holocene thaw unconformity at Mayo, Yukon Territory

1986 ◽  
Vol 23 (6) ◽  
pp. 794-803 ◽  
Author(s):  
C. R. Burn ◽  
F. A. Michel ◽  
M. W. Smith
Keyword(s):  
Oxygen Isotope ◽  
Average Rate ◽  
Climatic Conditions ◽  
Yukon Territory ◽  
Mackenzie Delta ◽  
Delta Area ◽  
The Holocene ◽  
Oxygen Isotope Ratios ◽  
Abrupt Changes ◽  
Mineralogical Evidence

Ice-rich glaciolacustrine sediments near Mayo, Yukon Territory, reveal a thaw unconformity in the form of truncated ice wedges and abrupt changes in cryotexture. The unconformity has been radiocarbon dated at 8870 ± 200 years BP, which is within the Holocene period of optimal climatic conditions in northern Yukon and the Mackenzie Delta area reported by other workers. Analysis of the mineralogy of the sediments indicates that the material above the unconformity is enriched in minerals that are the products of a more intense weathering environment than those deeper in the profile. Oxygen-isotope ratios of ground ice in the sediments suggest the presence of two genetically distinct ice units above and below the unconformity. An average rate of upward permafrost growth in this area of 0.1–0.2 mm year−1 is calculated for the period since the climatic optimum.

Atmospheric circulation and the differentiation of precipitation sources during the Holocene inferred from five stalagmite records from Demänová Cave System (Central Europe)

The Holocene ◽  
2020 ◽  
Vol 30 (6) ◽  
pp. 834-846
Author(s):  
Helena Hercman ◽  
Michał Gąsiorowski ◽  
Jacek Pawlak ◽  
Marcin Błaszczyk ◽  
Michał Gradziński ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Central Europe ◽  
Precipitation Amount ◽  
Climatic Conditions ◽  
Black Sea Region ◽  
The Holocene ◽  
Cave System ◽  
Oxygen Isotope Ratios ◽  
Stable Isotopic ◽  
Rayleigh Distillation

Five stalagmites from the Demänová Cave System (DCS, Western Carpathians, Slovakia), spanning the period from 13,000 to 500 a BP, were analyzed for their oxygen and carbon stable isotopic composition of the calcite. The isotopic data obtained from several stalagmites located in one cave system allow us to separate the changes of regional/global importance from the local changes. Oxygen isotope ratios point to dynamic changes in the environment at the onset of the Holocene. Despite the local differences, carbon isotope data express the gradual and steady development of vegetation on the surface above the cave from the beginning of the Holocene until 6,000 a BP. The oxygen isotope values in the DCS stalagmites are higher than that derived from the Rayleigh distillation model until approximately 9,000 a BP, suggesting (1) an increase in the isotopic gradient to the east of Europe, probably caused by a different seasonality in precipitation amount or (2) different sources of meteoric water, transported from the Mediterranean and Black Sea region, in Central and Eastern Europe compared to the Western, circum-Atlantic part of the continent. The younger part of the DCS records falls in the range described by the model and points to the increasing role of the westerlies in the determination of the climatic conditions of Central Europe during middle- and late-Holocene.

Secular changes in the oxygen isotope ratios of mollusc shells during the Holocene of Central Japan

1987 ◽  
Vol 61 ◽  
pp. 155-166 ◽  
Author(s):  
Kiyotaka Chinzei ◽  
Hiroko Koike ◽  
Tadamichi Oba ◽  
Yoshiaki Matsushima ◽  
Hiroshi Kitazato
Keyword(s):  
Oxygen Isotope ◽  
Isotope Ratios ◽  
Central Japan ◽  
The Holocene ◽  
Secular Changes ◽  
Oxygen Isotope Ratios ◽  
Mollusc Shells

Cryostratigraphy of the Klondike "muck" deposits, west-central Yukon Territory

2000 ◽  
Vol 37 (6) ◽  
pp. 849-861 ◽  
Author(s):  
E Kotler ◽  
C R Burn
Keyword(s):  
Abrupt Change ◽  
Late Quaternary ◽  
Yukon Territory ◽  
Valley Bottom ◽  
Glacial Sediments ◽  
The Holocene ◽  
Oxygen Isotope Ratios ◽  
Bottom Deposits ◽  
Late Wisconsinan ◽  
Lower Contact

Four late Quaternary cryostratigraphic units are recognized in the unconsolidated valley-bottom deposits of the Klondike area, Yukon Territory. Three of the units, in ice-rich, loessal sediments of pre-Wisconsinan or Wisconsinan age, collectively compose the King Solomon Formation. They are overlain by a Holocene organic unit. The units are distinguished by their cryostratigraphic characteristics and oxygen-isotope ratios of included ground ice. The basal unit is the Last Chance Creek Member, a pre-Late Wisconsinan deposit, containing preserved ice wedges δ18O ~ -28 to -26‰; δD ~ -225 to -209‰). The overlying Quartz Creek Member, a Late Wisconsinan unit, is dominated by organic-rich loess. Massive ice is noticeably absent, although the sediments are ice rich. The isotopic composition of ice in this unit is characteristic of full-glacial conditions (δ18O ~ -32 to -29‰; δD ~ -234 to -257‰). An abrupt change to warmer and wetter conditions at the end of glaciation, prior to the Holocene, is recorded by the ice-rich, colluviated Dago Hill Member (δ18O ~ -28 to -21‰; δD ~ -164 to -225‰), which began accumulating by 11.62 14C ka BP. Large ice wedges originate in this unit, and, in places, penetrate the underlying full-glacial sediments. Even higher δ18O and δD values occur for ice in the Holocene organic unit (δ18O ~ -25 to -20‰; δD ~ -164 to -189‰). The majority of the massive icy bodies in the King Solomon Formation are ice wedges, but pool ice and aggradational ice are also exposed, especially in the Dago Hill Member. Massive icy beds formed by groundwater intrusion into permafrost occur at the lower contact of the Quartz Creek Member.

scholarly journals Spring-summer temperatures since AD 1780 reconstructed from stable oxygen isotope ratios in white spruce tree-rings from the Mackenzie Delta, northwestern Canada

2013 ◽  
Vol 42 (3-4) ◽  
pp. 771-785 ◽  
Author(s):  
Trevor J. Porter ◽  
Michael F. J. Pisaric ◽  
Robert D. Field ◽  
Steven V. Kokelj ◽  
Thomas W. D. Edwards ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Tree Rings ◽  
White Spruce ◽  
Isotope Ratios ◽  
Mackenzie Delta ◽  
Stable Oxygen Isotope ◽  
Oxygen Isotope Ratios ◽  
Summer Temperatures ◽  
Stable Oxygen

Sequence stratigraphy, biotic change, 87Sr/86Sr record, paleoclimatic history, and sedimentation rate change across a regional late Cenozoic unconformity in Arctic Canada

2001 ◽  
Vol 38 (2) ◽  
pp. 309-331 ◽  
Author(s):  
D H McNeil ◽  
A Duk-Rodkin ◽  
J Dixon ◽  
J R Dietrich ◽  
J M White ◽  
...  
Keyword(s):  
Late Miocene ◽  
Fold Increase ◽  
Climatic Conditions ◽  
The Arctic ◽  
Mackenzie Delta ◽  
Arctic Canada ◽  
Deep Basin ◽  
Delta Area ◽  
Biotic Change ◽  
Richardson Mountains

Eustasy, tectonics, and climate contributed to a remarkable Miocene–Pliocene regional unconformity in the Beaufort–Mackenzie area of Arctic Canada. The unconformity extends from beneath deep basin turbidites on the continental rise, upslope across an erosional paleocontinental shelf, onto the cratonic margin as a regional paleosurface (peneplain) in the Mackenzie Delta area, and into pediment surfaces cut into the orogenic highlands of the Richardson Mountains. The unconformity was initiated by shelf exposure during latest Messinian or earliest Pliocene eustatic lowstand and was accentuated by tectonic uplift from the culmination of a major Late Miocene compressional pulse on the basin margin. Palynomorph, benthic foraminiferal, strontium isotopic, paleomagnetic, and radiometric data document the climatic and chronological events surrounding the unconformity. A widespread hardground (K-59 limestone) occurs at the unconformity and caps the Late Miocene Akpak Sequence. The hardground yields the benthic foraminifera Cibicides grossus, a regional marker in the Arctic Pliocene, and the bryozoan Adeonella sp. aff. A. polystomella, previously known from temperate North Atlantic environments. The 87Sr/86Sr data and new biostrati gra phic data indicate that the C. grossus Zone in the Beaufort–Mackenzie area may be younger than previously estimated, ranging into the earliest Pleistocene. Late Miocene regional uplift across the cratonic margin, coupled with eustatic lowstand followed by Early Pliocene tectonic quiescence and dry cool climatic conditions, combined to produce widespread erosion (pediments and peneplanation). Rapid erosion contributed to the >4 km-thick, Pliocene–Pleistocene Iperk Sequence and a 23-fold increase in sedimentation rates relative to the Early and Middle Miocene.

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