scholarly journals The first luminescence dating of Tibetan glacier basal sediment

2018 ◽  
Vol 12 (1) ◽  
pp. 163-168 ◽  
Author(s):  
Zhu Zhang ◽  
Shugui Hou ◽  
Shuangwen Yi
Keyword(s):  
Ice Cores ◽  
Luminescence Dating ◽  
High Mountain ◽  
Mountain Glaciers ◽  
Ice Cap ◽  
The North ◽  
Basal Ice ◽  
Order Of Magnitude ◽  
Western Tibetan Plateau ◽  
Drilling Site

Abstract. Dating ice cores drilled in the high mountain glaciers is difficult because seasonal variations cannot be traced at depth due to rapid thinning of the ice layers. Here we provide the first luminescence dating of the basal sediment of the Chongce ice cap in the north-western Tibetan Plateau. Assuming the sediment is of similar (or older) age as the surrounding ice, the luminescence dating of 42 ± 4 ka provides an upper constraint for the age of the bottom ice at the drilling site. This result is more than 1 order of magnitude younger than the previously suggested age of the basal ice of the nearby Guliya ice cap (∼ 40 km in distance).

scholarly journals The first luminescence dating of Tibetan glacier basal sediment

2017 ◽  
Author(s):  
Zhu Zhang ◽  
Shugui Hou ◽  
Shuangwen Yi
Keyword(s):  
Tibetan Plateau ◽  
Seasonal Variations ◽  
Ice Cores ◽  
Older Age ◽  
Luminescence Dating ◽  
High Mountain ◽  
Mountain Glaciers ◽  
Ice Cap ◽  
Basal Ice ◽  
Upper Limit

Abstract. Dating of ice cores drilled in the high mountain glaciers is difficult because seasonal variations cannot be traced at depth due to rapid thinning of the ice layers. Here we provide the first luminescence dating of the basal sediment of the Chongce ice cap in the northwest Tibetan Plateau. Assuming the sediment is of similar (or older) age as the surrounding ice, the dating result of 42 ± 4 ka provides an upper limit for the age of the ice cap. This result is more than one magnitude younger than the previously suggested age of the basal ice of the nearby Guliya ice cap (~ 40 km in distance).

scholarly journals Age ranges of the Tibetan ice cores with emphasis on the Chongce ice cores, western Kunlun Mountains

2018 ◽  
Vol 12 (7) ◽  
pp. 2341-2348 ◽  
Author(s):  
Shugui Hou ◽  
Theo M. Jenk ◽  
Wangbin Zhang ◽  
Chaomin Wang ◽  
Shuangye Wu ◽  
...  
Keyword(s):  
Ice Core ◽  
Ice Cores ◽  
High Elevation ◽  
The Other ◽  
Ice Cap ◽  
The North ◽  
Kunlun Mountains ◽  
Guliya Ice Core ◽  
Western Kunlun ◽  
Drilling Site

Abstract. An accurate chronology is the essential first step for a sound understanding of ice core records. However, dating ice cores drilled from the high-elevation glaciers is challenging and often problematic, leading to great uncertainties. The Guliya ice core, drilled to the bedrock (308.6 m in length) along the western Kunlun Mountains on the north-western Tibetan Plateau (TP) and widely used as a benchmark for palaeoclimate research, is believed to reach >500 ka (thousand years) at its bottom. Meanwhile other Tibetan ice cores (i.e. Dasuopu and East Rongbuk in the Himalayas, Puruogangri in the central TP and Dunde in the north-eastern TP) are mostly of Holocene origin. In this study, we drilled four ice cores into bedrock (216.6, 208.6, 135.8 and 133.8 m in length, respectively) from the Chongce ice cap ∼30 km to the Guliya ice core drilling site. We took measurements of 14C, 210Pb, tritium and β activity for the ice cores, and used these values in a two-parameter flow model to establish the ice core depth–age relationship. We suggested that the Chongce ice cores might be of Holocene origin, consistent with the other Tibetan ice cores except Guliya. The remarkable discrepancy between the Guliya and all the other Tibetan ice core chronology implies that more effort is necessary to explore multiple dating techniques to confirm the age ranges of the TP glaciers, including those from Chongce and Guliya.

Constraining ice core chronologies with 39Ar and 81Kr

2021 ◽  
Author(s):  
Florian Ritterbusch ◽  
Jinho Ahn ◽  
Ji-Qiang Gu ◽  
Wei Jiang ◽  
Giyoon Lee ◽  
...  
Keyword(s):  
Sample Size ◽  
Half Life ◽  
Earth Science ◽  
Noble Gas ◽  
Ice Core ◽  
Ice Cores ◽  
High Mountain ◽  
National Academy Of Sciences ◽  
Geophysical Research ◽  
Mountain Glaciers

<p>Paleoclimate reconstructions from ice core records can be hampered due to the lack of a reliable chronology, especially when the stratigraphy is disturbed and conventional dating methods cannot be readily applied. The noble-gas radioisotopes <sup>81</sup>Kr and <sup>39</sup>Ar can in these cases provide robust constraints as they yield absolute, radiometric ages. <sup>81</sup>Kr (half-life 229 ka) covers the time span of 50-1300 ka, which is particularly relevant for polar ice cores, whereas <sup>39</sup>Ar (half-life 269 a) with a dating range of 50-1800 a is suitable for high mountain glaciers. For a long time the use of <sup>81</sup>Kr and <sup>39</sup>Ar for dating of ice samples was hampered by the lack of a detection technique that can meet its extremely small abundance at a reasonable sample size.</p><p>Here, we present <sup>81</sup>Kr and <sup>39</sup>Ar dating of Antarctic and Tibetan ice cores with the detection method Atom Trap Trace Analysis (ATTA), using 5-10 kg of ice for <sup>81</sup>Kr and 2-5 kg for <sup>39</sup>Ar. Recent advances in further decreasing the sample size and increasing the dating precision will be discussed. Current studies include <sup>81</sup>Kr dating in shallow ice cores from the Larsen Blue ice area, East Antarctica, in order to retrieve climate signals from the last glacial termination. Moreover, an <sup>39</sup>Ar profile from a central Tibetan ice core has been obtained in combination with layer counting based on isotopic and visual stratigraphic signals. The presented studies demonstrate how <sup>81</sup>Kr and <sup>39</sup>Ar can constrain the age range of ice cores and complement other methods in developing an ice core chronology.</p><p> </p><p>[1] Z.-T. Lu, Tracer applications of noble gas radionuclides in the geosciences, Earth-Science Reviews 138, 196-214, (2014)<br>[2] C. Buizert, Radiometric <sup>81</sup>Kr dating identifies 120,000-year-old ice at Taylor Glacier, Antarctica, Proceedings of the National Academy of Sciences, <strong>111</strong>, 6876, (2014)</p><p>[3] L. Tian, <sup>81</sup>Kr Dating at the Guliya Ice Cap, Tibetan Plateau, Geophysical Research Letters, (2019)</p><p>http://atta.ustc.edu.cn</p>

scholarly journals Mass Balance and Thermal Regime of Laika Ice Cap, Coburg Island, N.W.T., Canada

1988 ◽  
Vol 34 (116) ◽  
pp. 102-110 ◽  
Author(s):  
Heinz Blatter ◽  
Giovanni Kappenberger
Keyword(s):  
Mass Balance ◽  
Temperature Measurements ◽  
Water Project ◽  
Ice Cap ◽  
The North ◽  
Basal Ice ◽  
Westerly Winds ◽  
North Water ◽  
History Of ◽  
Finite Layer

AbstractDuring the North Water Project of the late F. Müller, glaciological studies were carried out on Laika ice cap. In addition to the main climatological investigations, surveying, mapping, mass-balance studies, and englacial temperature measurements were carried out. The mass-balance distribution is strongly determined by the orography. Strong westerly winds erode and transport snow from exposed surfaces, whereas prevailing easterly winds, during precipitation, deposit snow on lee slopes. The balance is negative under the present climate. The history of the glacier-tongue geometry is reconstructed using geomorphological observations and photogrammetric mapping for 1959 and 1971. Englacial temperature measurements revealed a finite layer of temperate basal ice in the ablation zone. The temperature distribution in the accumulation area around the summit of the ice cap is not stationary.

scholarly journals Progress and prospect for research on mountain glaciers in China

1992 ◽  
Vol 16 ◽  
pp. 207-211
Author(s):  
Xie Zichu
Keyword(s):  
Soviet Union ◽  
Ice Core ◽  
Research Area ◽  
Tien Shan ◽  
High Mountain ◽  
Glacier Mass Balance ◽  
Mountain Glaciers ◽  
Ice Cap ◽  
Glacial Runoff ◽  
West Kunlun

In the past decade the interest of many scientists worldwide has been attracted to the central Asian area of China. A number of gaps in scientific knowledge have been closed, and many significant discoveries have been made.The most important achievement is the ice-core research by the Sino-American Joint Expedition to the Dunde Ice Cap, Qilian mountains, that established a record of ten thousand years of climatic and environmental change. In addition, in cooperation with scientists from Japan, Switzerland and the Soviet Union, studies have been carried out focusing on glacier mass balance, heat balance, the mechanism and formation of glacial runoff, and high mountain climates. This work has been done in the Tien Shan, west Kunlun, Tanggula, Nyaingentanglha and Gongga mountains.In addition, through joint efforts of scientists from China, Nepal and Canada, important advances have also been made in studies of glacier lake outburst floods and debris flows in the Karakoram and the Himalayas, and in mountainous areas in southeastern Tibet.The glaciers in central Asia will continue to be an important research area for glaciologists from all over the world in the coming decade.

Constraining ice core chronologies with 39Ar and 81Kr

2020 ◽  
Author(s):  
Florian Ritterbusch ◽  
Yan-Qing Chu ◽  
Ilaria Crotti ◽  
Xi-Ze Dong ◽  
Ji-Qiang Gu ◽  
...  
Keyword(s):  
Half Life ◽  
Earth Science ◽  
Noble Gas ◽  
Ice Core ◽  
Ice Cores ◽  
High Mountain ◽  
National Academy Of Sciences ◽  
Geophysical Research ◽  
Bottom Part ◽  
Mountain Glaciers

<p>Paleoclimate reconstructions from ice core records can be hampered due to the lack of a reliable chronology, especially when the stratigraphy is disturbed and conventional dating methods are not readily applied. The noble gas radioisotopes <sup>81</sup>Kr and <sup>39</sup>Ar can in these cases provide robust constraints as they yield absolute, radiometric ages. <sup>81</sup>Kr (half-life 229 ka) covers the time span from 50-1300 ka, which is particularly relevant for polar ice cores, whereas <sup>39</sup>Ar (half-life 269 a) with a dating range of 50-1400 a is suitable for high mountain glaciers. For a long time the use of <sup>81</sup>Kr and <sup>39</sup>Ar for dating of ice samples was hampered by the lack of a detection technique that can meet its extremely small abundance at a reasonable sample size. Here, we report on <sup>81</sup>Kr and <sup>39</sup>Ar dating of Antarctic and Tibetan ice cores with the detection method Atom Trap Trace Analysis (ATTA), using 5-10 kg of ice for <sup>81</sup>Kr and 2-5 kg for <sup>39</sup>Ar. Among others, we measured <sup>81</sup>Kr in the lower section of Taldice ice core, which is difficult to date by conventional methods, and in the meteoric bottom of the Vostok ice core in comparison with an age scale derived from hydrate growth. Moreover, we have obtained an <sup>39</sup>Ar profile for an ice core from central Tibet in combination with a timescale constructed by layer counting. The presented studies demonstrate how the obtained <sup>81</sup>Kr and <sup>39</sup>Ar ages can complement other methods in developing an ice core chronology, especially for the bottom part.</p><p>[1] Z.-T. Lu, Tracer applications of noble gas radionuclides in the geosciences, Earth-Science Reviews 138, 196-214, (2014)</p><p>[2] C. Buizert, Radiometric <sup>81</sup>Kr dating identifies 120,000-year-old ice at Taylor Glacier, Antarctica, Proceedings of the National Academy of Sciences, <strong>111</strong>, 6876, (2014)</p><p>[3] L. Tian, <sup>81</sup>Kr Dating at the Guliya Ice Cap, Tibetan Plateau, Geophysical Research Letters, (2019)</p><p>[4] http://atta.ustc.edu.cn</p>

scholarly journals Reliability analysis for design of stake networks to measure glacier surface velocity

1999 ◽  
Vol 45 (149) ◽  
pp. 154-164 ◽  
Author(s):  
C. David Chadwell
Keyword(s):  
Ice Cores ◽  
Maximum Size ◽  
Surface Velocity ◽  
Internal Reliability ◽  
Glacier Surface ◽  
Flow Models ◽  
Ice Caps ◽  
Ice Cap ◽  
The North ◽  
Least Squares Adjustment

Abstract Measurement of glacier surface velocity provides some constraint on glacier flow models used to date ice cores recovered near the flow divide of remote high-altitude ice caps. The surface velocity is inferred from the change in position of a network of stakes estimated from the least-squares adjustment of geodetic observations – terrestrial and/or spaced-based – collected approximately 1 year apart. The lack of outliers in and the random distribution of the post-fit observation residuals are regarded as evidence that the observations contain no blunders. However, if the network lacks sufficient geometric redundancy, the estimated stake positions can shift to fit erroneous observations. To determine the maximum size of these potential undetected shifts, given the covariance of the observations and the approximate network geometry, expressions are developed to analyze a network for redundancy number and marginally detectable blunders (internal reliability), and the position shifts from marginally detectable blunders (external reliability). Two stake networks, one on the col of Huascar–n (9°–07'S, 77°–37'W; 6050 m a.s.l.) in the north-central Andes of Peru and one on the Guliya ice cap (35°–17'N, 81°–29'E; 6200 m a.s.l.) on the Qinghai–Tibetan Plateau in China, are examined for precision and internal and external reliability.

scholarly journals Reliability analysis for design of stake networks to measure glacier surface velocity

1999 ◽  
Vol 45 (149) ◽  
pp. 154-164 ◽  
Author(s):  
C. David Chadwell
Keyword(s):  
Ice Cores ◽  
Maximum Size ◽  
Surface Velocity ◽  
Internal Reliability ◽  
Glacier Surface ◽  
Flow Models ◽  
Ice Caps ◽  
Ice Cap ◽  
The North ◽  
Least Squares Adjustment

AbstractMeasurement of glacier surface velocity provides some constraint on glacier flow models used to date ice cores recovered near the flow divide of remote high-altitude ice caps. The surface velocity is inferred from the change in position of a network of stakes estimated from the least-squares adjustment of geodetic observations – terrestrial and/or spaced-based – collected approximately 1 year apart. The lack of outliers in and the random distribution of the post-fit observation residuals are regarded as evidence that the observations contain no blunders. However, if the network lacks sufficient geometric redundancy, the estimated stake positions can shift to fit erroneous observations. To determine the maximum size of these potential undetected shifts, given the covariance of the observations and the approximate network geometry, expressions are developed to analyze a network for redundancy number and marginally detectable blunders (internal reliability), and the position shifts from marginally detectable blunders (external reliability). Two stake networks, one on the col of Huascar–n (9°–07'S, 77°–37'W; 6050 m a.s.l.) in the north-central Andes of Peru and one on the Guliya ice cap (35°–17'N, 81°–29'E; 6200 m a.s.l.) on the Qinghai–Tibetan Plateau in China, are examined for precision and internal and external reliability.

scholarly journals Mass Balance and Thermal Regime of Laika Ice Cap, Coburg Island, N.W.T., Canada

1988 ◽  
Vol 34 (116) ◽  
pp. 102-110 ◽  
Author(s):  
Heinz Blatter ◽  
Giovanni Kappenberger
Keyword(s):  
Mass Balance ◽  
Temperature Measurements ◽  
Water Project ◽  
Ice Cap ◽  
The North ◽  
Basal Ice ◽  
Westerly Winds ◽  
North Water ◽  
History Of ◽  
Finite Layer

AbstractDuring the North Water Project of the late F. Müller, glaciological studies were carried out on Laika ice cap. In addition to the main climatological investigations, surveying, mapping, mass-balance studies, and englacial temperature measurements were carried out. The mass-balance distribution is strongly determined by the orography. Strong westerly winds erode and transport snow from exposed surfaces, whereas prevailing easterly winds, during precipitation, deposit snow on lee slopes. The balance is negative under the present climate. The history of the glacier-tongue geometry is reconstructed using geomorphological observations and photogrammetric mapping for 1959 and 1971. Englacial temperature measurements revealed a finite layer of temperate basal ice in the ablation zone. The temperature distribution in the accumulation area around the summit of the ice cap is not stationary.

scholarly journals Glacial Stage Ice-Core Records from the Subtropical Dunde Ice Cap, China

1990 ◽  
Vol 14 ◽  
pp. 288-297 ◽  
Author(s):  
L.G. Thompson ◽  
E. Mosley-Thompson ◽  
M.E. Davis ◽  
J.F. Bolzan ◽  
J. Dai ◽  
...  
Keyword(s):  
Accumulation Rate ◽  
Ice Core ◽  
Ice Cores ◽  
Major Change ◽  
Late Glacial ◽  
Ice Cap ◽  
The North ◽  
Glacial Stage ◽  
Isotope Record ◽  
Temperature Proxy

The first ice-core record of both the Holocene and Wisconsin/Würm Late Glacial Stage (LGS) from the subtropics has been extracted from three ice cores to bedrock from the Dunde ice cap on the north-central Qinghai-Tibetan Plateau. Ice thicknesses at the ice-cap summit average 138 m, the bedrock surface is relatively flat, surface and basal temperatures are −7.3 and −4.7°C, respectively and the ice cap exhibits radial flow away from the summit dome. These records reveal a major change in the climate of the plateau ∼10 000 years ago and suggest that LGS conditions were colder, wetter and dustier than Holocene conditions. This is inferred from the more negative δ18O ratios, increased dust content, decreased soluble aerosol concentrations, and reduced ice-crystal sizes, which characterize the LGS part of the cores. Total β radioactivity from shallow ice cores indicates that over the last 24 years the average accumulation rate has been ∼400 mm a−1 at the summit. The ice cores have been dated using a combination of annual layers in the insoluble dust and δ18O in the upper sections of core, visible dust layers which are annual, and ice-flow modeling. The oxygen-isotope record which serves as a temperature proxy indicates that the last 60 years have been the warmest in the entire record.

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