scholarly journals Luminescence dating of lacustrine sediments from CUOE Lake on the central Tibetan Plateau

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Yandong Hou ◽  
Hao Long ◽  
Lei Gao ◽  
Ji Shen
Keyword(s):  
Tibetan Plateau ◽  
Lacustrine Sediments ◽  
Water Reservoir ◽  
Hard Water ◽  
Luminescence Dating ◽  
Coarse Grained ◽  
The Tibetan Plateau ◽  
Sediment Layer ◽  
Central Tibetan Plateau ◽  
Dating Method

AbstractLuminescence dating technology has been used for chronological constraints on lacustrine sediments due to the ubiquitous materials (e.g., quartz and feldspar) as dosimeters, and a relatively long dating range, compared with the commonly used radiocarbon dating method. However, quartz dating on the Tibetan Plateau may suffer from dim and unstable luminescence signals. In the current study, we investigate a lake-related outcrop from the shore of Cuoe Lake on the central Tibetan Plateau. Both coarse-grained quartz and K-feldspar fractions were extracted, and OSL and post-IR IRSL signals were measured from these fractions, respectively. Combining the stratigraphy analysis and dating results, this study shows that: (1) quartz appears to be unsuitable for dating because of very dim natural signals and even anomalous fading (average g-value: 4.30 ± 2.51 %/decade). The suitability of the applied pIRIR protocol measured at 150°C (pIRIR150) for K-feldspar samples was confirmed by a set of luminescence tests; (2) compared with the luminescence-based chronology, the 14C age of shells from the same sediment layer yielded older age by ~7 ka, which is likely attributed to hard water reservoir effect in Cuoe Lake; (3) the lake level reached its peak and maintained high-stand during the early Holocene (~9.4–7.1 ka). This study highlights the applicability of K-feldspar luminescence dating when the counterpart quartz OSL is insensitive and encounters anomalous fading.

scholarly journals Radiocarbon and Luminescence Dating of Lacustrine Sediments in Zhari Namco, Southern Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Lu Cong ◽  
Yixuan Wang ◽  
Xiying Zhang ◽  
Tianyuan Chen ◽  
Donglin Gao ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
Lacustrine Sediments ◽  
Lacustrine Sediment ◽  
Luminescence Dating ◽  
Complex Nature ◽  
The Tibetan Plateau ◽  
Paleoenvironmental Changes ◽  
Bulk Organic Matter ◽  
Osl Age

There are more than 1,000 lakes within the Tibetan Plateau (TP), all of which are sensitive to changes in regional climate and local hydrology. Lacustrine sediments within these lakes preserve a good record of these changes. However, determining their precise ages is difficult due to the complex nature of lake reservoir effects (LRE), which limit our understanding of paleoenvironmental changes. Focusing on an exposed 600 cm thick lacustrine sediment profile located in western Zhari Namco, we used a combination of both radiocarbon and optically stimulated luminescence (OSL) dating methods in order to evaluate the carbon reservoirs of bulk organic matter (BOM) and aquatic plant remnants (APR), and to explore the age differences between 14C and OSL and their respective reliability. We demonstrated that (i) OSL ages were changed in stratigraphic order, and the OSL age just below the beach gravel layer was consistent with previously reported paleoshoreline ages; (ii) 14C ages were divergent between BOM and grass leaves; (iii) 14C ages of BOM were older than 14C ages of APR; and (iv) all 14C ages were older than OSL ages. This could be attributed to changing LRE in the past, causing the 14C ages to appear unstable during the deposition period. Although the 14C ages of terrestrial plant remnants (TPR) were not affected by LRE, an analyzed twig nonetheless returned a 14C age older than its respective layer’s OSL age, suggesting it may have been preserved on land prior to transportation into the lake. Our study suggests that OSL ages are more reliable than 14C ages with respect to Zhari Namco lacustrine sediments. We recommend caution when interpreting paleoenvironmental changes based on lacustrine sediment 14C ages alone.

A lake-level chronology based on feldspar luminescence dating of beach ridges at Tangra Yum Co (Southern Tibet)

2015 ◽  
Vol 83 (3) ◽  
pp. 469-478 ◽  
Author(s):  
Eike F. Rades ◽  
Sumiko Tsukamoto ◽  
Manfred Frechen ◽  
Qiang Xu ◽  
Lin Ding
Keyword(s):  
Tibetan Plateau ◽  
Lake Level ◽  
Environmental Changes ◽  
Luminescence Dating ◽  
Rapid Decline ◽  
The Tibetan Plateau ◽  
Southern Tibet ◽  
Beach Ridges ◽  
Slow Decline ◽  
Fast Decline

Many lakes on the Tibetan Plateau exhibit strandplains with a series of beach ridges extending high above the current lake levels. These beach ridges mark former lake highstands and therefore dating their formation allows the reconstruction of lake-level histories and environmental changes. In this study, we establish a lake-level chronology of Tangra Yum Co (fifth largest lake on the Tibetan Plateau) based on luminescence dating of feldspar from 17 beach-ridge samples. The samples were collected from two strandplains southeast and north of the lake and range in elevation from the current shore to 140 m above the present lake. Using a modified post-infrared IRSL protocol at 170°C we successfully minimised the anomalous fading in the feldspar IRSL signal, and obtained reliable dating results. The luminescence ages indicate three different stages of lake-level decline during the Holocene: (1) a phase of rapid decline (~ 50 m) from ~ 6.4 to ~ 4.5 ka, (2) a period of slow decline between ~ 4.5 and ~ 2.0 ka (~ 20 m), and (3) a fast decline by 70 m between ~ 2 ka and today. Our findings suggest a link between a decrease in monsoonal activity and lake-level decline since the early Holocene.

scholarly journals <sup>10</sup>Be systematics in the Tsangpo-Brahmaputra catchment: the cosmogenic nuclide legacy of the eastern Himalayan syntaxis

2017 ◽  
Author(s):  
Maarten Lupker ◽  
Jérôme Lavé ◽  
Christian France-Lanord ◽  
Marcus Christl ◽  
Didier Bourlès ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Sediment Flux ◽  
Coarse Grained ◽  
The Tibetan Plateau ◽  
Data Set ◽  
Denudation Rate ◽  
Cosmogenic Nuclide ◽  
Denudation Rates ◽  
The Impact ◽  
Eastern Himalayan Syntaxis

Abstract. The Tsangpo-Brahmaputra River drains the eastern part of the Himalayan range, flowing from the Tibetan Plateau through the eastern Himalayan syntaxis and downstream to the Indo-Gangetic floodplain. As such it is a unique natural laboratory to study how denudation and sediment production processes are transferred to river detrital signals. In this study, we present a new 10Be data set to constrain denudation rates across the catchment and to quantify the impact of rapid erosion within the syntaxis region on cosmogenic nuclide budgets and signals. 10Be denudation rates span around two orders of magnitude across the catchments (ranging from 0.03 mm/yr to > 4 mm/yr) and sharply increase as the Tsangpo-Brahmaputra flows across the eastern Himalaya. The increase in denudation rates however occurs ~ 150 km downstream of the Namche Barwa-Gyala Peri massif (NBGPm), an area which has been previously characterized by extremely high erosion and exhumation rates. We suggest that this downstream lag is mainly due to the physical abrasion of coarse grained, low 10Be concentration, landslide material produced within the syntaxis that dilutes the upstream high concentration 10Be flux from the Tibetan Plateau only after abrasion has transferred sediment to the studied sand fraction. A simple abrasion model produces typical lag distances of 50 to 150 km compatible with our observations. Abrasion effects reduce the spatial resolution over which denudation can be constrained in the eastern Himalayan syntaxis. In addition, we also highlight that denudation rate estimates are dependent on the sediment connectivity, storage and quartz content of the upstream Tibetan Plateau part of the catchment which tends to lead to an overestimation of downstream denudations rates. Taking these effects into account we estimate a denudation rates of ca. 2 to 5 mm/yr for the entire syntaxis and ca. 4 to 28 mm/yr for the NBGPm, which is significantly higher than other to other large catchments. Overall, 10Be concentrations measured at the outlet of the Tsangpo-Brahmaputra in Bangladesh suggest a sediment flux between 780 and 1430 Mt/yr equivalent to a denudation rate between 0.7 and 1.2 mm/yr for the entire catchment.

First mid-ocean ridge-type ophiolite from the Meso-Tethys suture zone in the north-central Tibetan plateau

2020 ◽  
Vol 132 (9-10) ◽  
pp. 2202-2220 ◽  
Author(s):  
Yue Tang ◽  
Qing-Guo Zhai ◽  
Sun-Lin Chung ◽  
Pei-Yuan Hu ◽  
Jun Wang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ocean Basin ◽  
Suture Zone ◽  
The Tibetan Plateau ◽  
Spreading Ridge ◽  
North Central ◽  
The North ◽  
Central Tibetan Plateau ◽  
Mid Ocean Ridge ◽  
Ocean Ridge

Abstract The Meso-Tethys was a late Paleozoic to Mesozoic ocean basin between the Cimmerian continent and Gondwana. Part of its relicts is exposed in the Bangong–Nujiang suture zone, in the north-central Tibetan Plateau, that played a key role in the evolution of the Tibetan plateau before the India-Asia collision. A Penrose-type ophiolitic sequence was newly discovered in the Ren Co area in the middle of the Bangong–Nujiang suture zone, which comprises serpentinized peridotites, layered and isotropic gabbros, sheeted dikes, pillow and massive basalts, and red cherts. Zircon U-Pb dating of gabbros and plagiogranites yielded 206Pb/238U ages of 169–147 Ma, constraining the timing of formation of the Ren Co ophiolite. The mafic rocks (i.e., basalt, diabase, and gabbro) in the ophiolite have uniform geochemical compositions, coupled with normal mid-ocean ridge basalt-type trace element patterns. Moreover, the samples have positive whole-rock εNd(t) [+9.2 to +8.3], zircon εHf(t) [+17 to +13], and mantle-like δ18O (5.8–4.3‰) values. These features suggest that the Ren Co ophiolite is typical of mid-ocean ridge-type ophiolite that is identified for the first time in the Bangong–Nujiang suture zone. We argue that the Ren Co ophiolite is the relic of a fast-spreading ridge that occurred in the main oceanic basin of the Bangong–Nujiang segment of Meso-Tethys. Here the Meso-Tethyan orogeny involves a continuous history of oceanic subduction, accretion, and continental assembly from the Early Jurassic to Early Cretaceous.

Acricotopus indet. morphotype incurvatus: Description and genetics of a new Orthocladiinae (Diptera: Chironomidae) larval morphotype from the Tibetan Plateau

Zootaxa ◽  
2019 ◽  
Vol 4656 (3) ◽  
pp. 535-544
Author(s):  
ANDREAS LAUG ◽  
LADISLAV HAMERLÍK ◽  
STEN ANSLAN ◽  
STEFAN ENGELS ◽  
FALKO TURNER ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Mitochondrial Coi ◽  
Mountain Ranges ◽  
Central Tibetan Plateau ◽  
Peculiar Form ◽  
Close Proximity ◽  
Coi Sequences ◽  
Complex Formations

High mountain ranges such as the Tibetan Plateau with an average altitude above 4500 m are topographically complex formations. Elevational gradients, physiographic diversity and climatic heterogeneity have led to highly biodiverse ecosystems in these regions. Mountain ranges can be seen as cradles of evolution and harbour, due to their unique characteristics, a high number of highly adapted species. At the same time these areas are hard to access and therefore taxonomic information is limited. Here we describe a new Acricotopus (Diptera: Chironomidae: Orthocladiinae) larval morphotype occurring in lakes and ponds of differing salinity and water depths located on the Southern and Central Tibetan Plateau. The description is based on larvae and their genetics (ribosomal 18S, 28S and mitochondrial COI sequences) collected from a shallow pond in close proximity to the large saline lake Selin Co. Larvae of Acricotopus indet. morphotype incurvatus are characterized by a mentum with a cluster of lateral teeth, partially folded inwards, a mandible with a toothed lobe in addition to four inner teeth and a sclerotized plate positioned behind the mentum. Up to now, these morphological features have only been found in early instars of other Acricotopus species. The proposed morphotype name is inspired by the peculiar form of the mentum. 

scholarly journals Summer Atmospheric Heat Sources over the Western–Central Tibetan Plateau: An Integrated Analysis of Multiple Reanalysis and Satellite Datasets

2019 ◽  
Vol 32 (4) ◽  
pp. 1181-1202 ◽  
Author(s):  
Zhiling Xie ◽  
Bin Wang
Keyword(s):  
Tibetan Plateau ◽  
Integrated Analysis ◽  
Mountain Range ◽  
The Tibetan Plateau ◽  
Heat Sources ◽  
Central Tibetan Plateau ◽  
New Finding ◽  
Highly Correlated ◽  
Atmospheric Heat ◽  
Heat Released

Multiple bias-corrected top-quality reanalysis datasets, gauge-based observations, and selected satellite products are synthetically employed to revisit the climatology and variability of the summer atmospheric heat sources over the Tibetan Plateau (TP). Verification-based selection and ensemble-mean methods are utilized to combine various datasets. Different from previous works, this study pays special attention to estimating the total heat source (TH) and its components over the data-void western plateau (70°–85°E), including the surface sensible heat (SH), latent heat released by precipitation (LH), and net radiation flux (RD). Consistent with previous studies, the climatology of summer SH (LH) typically increases (decreases) from southeast to northwest. Generally, LH dominates TH over most of the TP. A notable new finding is a minimum TH area over the high-altitude region of the northwestern TP, where the Karakoram mountain range is located. We find that during the period of 1984–2006, TH shows insignificant trends over the eastern and central TP, whereas it exhibits an evident increasing trend over the western TP that is attributed to the rising tendency of LH before 1996 and to that of RD after 1996. The year-to-year variation of TH over the central–eastern TP is highly correlated with that of LH, but that is not the case over the western TP. It is also worth noting that the variations of TH in each summer month are not significantly correlated with each other, and hence study of the interannual variation of the TP heat sources should consider the remarkable subseasonal variations.

Late Holocene Varve Chronology and High-Resolution Records of Precipitation in the Central Tibetan Plateau

2020 ◽  
Author(s):  
Kejia Ji ◽  
Erlei Zhu ◽  
Guoqiang Chu ◽  
Juzhi Hou
Keyword(s):  
Tibetan Plateau ◽  
Lake Sediment ◽  
Sediment Cores ◽  
Coarse Grained ◽  
The Tibetan Plateau ◽  
Past Climate ◽  
Environment Changes ◽  
The Past ◽  
Varve Chronology ◽  
Past 2000 Years

&lt;p&gt;Precise age controls are fundamental prerequisites for reconstructing past climate and environment changes. Lakes on the Tibetan Plateau are one of the important archives for studying past climate and environment changes. However, radiocarbon ages for lake sediment core are subject to old radiocarbon reservoir effects, which caused severe problems in constructing age controls for lake sediment cores, especially on the Tibetan Plateau (TP). Here we present a varve chronology over the past 2000 years at Jiang Co on the central TP. The clastic-biogenic varves comprise of a coarse-grained layer and a fine-grained layer observed by petrographic microscope and Electron Probe Micro Analyzer. Varve chronology is supported by measurements of &lt;sup&gt;210&lt;/sup&gt;Pb and &lt;sup&gt;137&lt;/sup&gt;Cs, which is further used to determine the radiocarbon reservoir ages in the past ~2000 years. The percentage of coarse-grain layer thickness within single varves was considered as proxy for precipitation as the coarse grains were mainly transported by runoff, which is highly correlated with local meteorological observation. During the past 2000 years, the precipitation records show centennial-scale fluctuations that are consistent with regional records. The varve chronology at Jiang Co provides a valuable opportunity to examine variation in reservoir ages on the TP and a robust chronology for reconstructing paleoclimate.&lt;/p&gt;

Recent seismic events preserved in lacustrine sediments from the SE Tibetan Plateau

2020 ◽  
Author(s):  
Yongbo Wang ◽  
Xuezhi Ma ◽  
Zhenyu Ni
Keyword(s):  
Grain Size ◽  
Tibetan Plateau ◽  
Sediment Cores ◽  
Lacustrine Sediments ◽  
Size Composition ◽  
Recurrence Time ◽  
Seismic Events ◽  
Lake Basin ◽  
The Tibetan Plateau ◽  
Fine Clay

&lt;p&gt;Large earthquakes are regarded as important contributors to long-term erosion rates and considerable hazard to infrastructure and society, which were difficult to track because of the long recurrence time exceeding the time span of historical records. Geological records, especially the continuously accumulated lacustrine sediments, hold the potential to capture signals of prehistoric seismic events, which has been barely reported from the Tibetan Plateau. Here we present lacustrine sediment records recovered from Basom Tso in Southeastern Tibetan Plateau, in which two seismic events were preserved. Sediment lithology, grain size composition, magnetic susceptibility and XRF scanning induced element compositions showed dramatic variations in two turbidite-like sediment segments. Particularly, the grain size showed an abrupt increase at the bottom of the Turbidites which was followed by a fining-up pattern and covered by a fine clay cap, expressing similar sedimentary processes caused by the seiche effect triggered by seismic events. Consistent patterns were recorded in the element contents as well, i.e. obvious bias in the counts of Fe, Zr, Ti, Ca. In addition, scuh pattern were preserved in sediment cores from different part of the lake basin, indicating a basin wide event layer. Finally, according to the dating results from &lt;sup&gt;137&lt;/sup&gt;Cs and &lt;sup&gt;14&lt;/sup&gt;C, the two Turbidites were formed around 1950 A.D. and during the late18&lt;sup&gt;th&lt;/sup&gt;/early 19&lt;sup&gt;th&lt;/sup&gt; century respectively. Such information was further confirmed by historical earthquake records that Chayu Earthquake (M=8.6, 1950 A.D.) and Nyingchi Earthquake (M=6.75, 1845 A.D.) have possibly responsible for the slump of underwater sediments and the formation of these two turbidites.&lt;/p&gt;

Extending the paleoglaciological record of the southeastern Tibetan Plateau by combining geochronological and high-resolution remote sensing techniques

2020 ◽  
Author(s):  
Arjen P. Stroeven ◽  
Ramona A.A. Schneider ◽  
Robin Blomdin ◽  
Natacha Gribenski ◽  
Marc W. Caffee ◽  
...  
Keyword(s):  
High Resolution ◽  
Tibetan Plateau ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Luminescence Dating ◽  
The Tibetan Plateau ◽  
Exposure Dating ◽  
Southeastern Margin ◽  
Downstream Communities

&lt;p&gt;Paleoglaciological data is a crucial source of information towards insightful paleoclimate reconstructions by providing vital boundary conditions for regional and global climate models. In this context, the Third Pole Environment is considered a key region because it is highly sensitive to global climate change and its many glaciers constitute a diminishing but critical supply of freshwater to downstream communities in SE Asia. Despite its importance, extents of past glaciation on the Tibetan Plateau remain poorly documented or controversial largely because of the lack of well define glacial chronostratigraphies and reconstructions of former glacier extent. This study contributes to a better documentation of the extent and improved resolution of the timing of past glaciations on the southeastern margin of the Tibetan Plateau. We deploy a high-resolution TanDEM-X Digital Elevation Model (12 m resolution) to produce maps of glacial and proglacial fluvial landforms in unprecedented detail. Geomorphological and sedimentological field observations complement the mapping while cosmogenic nuclide exposure dating of quartz samples from boulders on end moraines detail the timing of local glacier expansion. Additionally, samples for optically stimulated luminescence dating were taken from extensive and distinct terraces located in pull-apart basins downstream of the end moraines to determine their formation time. We compare this new dataset with new and published electron spin resonance ages from terraces. Temporal coherence between the different chronometers strengthens the geochronological record while divergence highlights limitations in the applicability of the chronometers to glacial research or in our conceptual understanding of landscape changes in tectonic regions. Results highlight our current understanding of paleoglaciation, landscape development, and paleoclimate on the SE Tibetan Plateau.&lt;/p&gt;

scholarly journals OSL Chronology of the Siling Co Paleolithic Site in Central Tibetan Plateau

2021 ◽  
Vol 9 ◽  
Author(s):  
Lan Luo ◽  
Zhongping Lai ◽  
Wenhao Zheng ◽  
Yantian Xu ◽  
Lupeng Yu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ground Surface ◽  
Early Holocene ◽  
Archaeological Sites ◽  
Stratigraphic Correlation ◽  
The Tibetan Plateau ◽  
Paleolithic Site ◽  
Humid Climate ◽  
Climate Conditions ◽  
Central Tibetan Plateau

When and how was the Tibetan Plateau (TP), one of the least habitable regions on Earth, occupied by humans are important questions in the research of human evolution. Among tens of Paleolithic archaeological sites discovered over the past decades, only five are considered coeval with or older than the Last Glacial Maximum (LGM, ∼27–19 ka). As one of them, the Siling Co site in the central TP was previously announced to be ∼40–30 ka based on radiocarbon dating and stratigraphic correlation. Given the loose chronological constraint in previous studies, we here re-examined the chronology of the Siling Co site with the optically stimulated luminescence (OSL) dating technique. Four sections from the paleo-shoreline at an elevation of ∼4,600 m in southeastern Siling Co were investigated, with stone artifacts found from the ground surface. Dating results of nine samples delineated the age of ∼4,600 m paleo-shoreline to be ∼10–7 ka (∼8.54 ± 0.21 ka in average). This age indicates that the Siling Co site is not earlier than the early Holocene, much younger than the former age. The revised age of the Siling Co site is consistent with the wet and humid climate conditions on the TP during the early Holocene.

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