Sedimentary evidence and luminescence and ESR dating of Early Pleistocene high lake levels of Megalake Tengger, northwestern China

2020 ◽  
Vol 35 (8) ◽  
pp. 994-1006
Author(s):  
Fan Yuxin ◽  
Li Zhenjun ◽  
Yang Guangliang ◽  
Yi Shuangwen ◽  
Zhang Qingsong ◽  
...  
Keyword(s):  
Northwestern China ◽  
Early Pleistocene ◽  
Esr Dating ◽  
Lake Levels ◽  
High Lake Levels

scholarly journals Intraspecific divergences and phylogeography of Panzerina lanata (Lamiaceae) in Northwest China

2018 ◽  
Author(s):  
Yanfen Zhao ◽  
Hongxiang Zhang ◽  
Borong Pan ◽  
Mingli Zhang
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
Population Genetic ◽  
Divergence Time ◽  
Northwest China ◽  
Northwestern China ◽  
Intraspecific Diversity ◽  
Early Pleistocene ◽  
Helan Mountains ◽  
The Impact

Climactic fluctuations during the Quaternary played a crucial role in genetic diversity and population genetic structure of many plant species in northwestern China. In order to understand the impact of climate change on herbaceous plants, we studied Panzerina lanata (Lamiaceae), a widely distributed species. Two chloroplast DNA intergenic spacers (trnH-psbA and rpoB-trnC) were used to sequence 269 individuals from 27 populations and seven haplotypes were identified. Genetic structure and demographic characteristics were estimated using AMOVA, neutrality tests, and mismatch distribution analyses. The divergence times between the seven haplotypes were estimated using Beast. Our results revealed high levels of total genetic diversity (HT = 0.673±0.0869) and low levels of average within-population genetic diversity (HS = 0.033±0.0214). The analysis of molecular variance indicated major genetic differentiation among the three groups: northern, central, and eastern group. The species distribution modeling and demographic analysis indicated that P. lanata has not experience a recent range expansion. The divergence time within P. lanata occurred between the early Pleistocene and the late Pleistocene, which coincides with aridification and the expansion of the deserts in northwestern China that resulted in species diversification and habitat fragmentation. In addition, we speculate that the deserts and the Helan Mountains acted as effective geographic barriers that led to intraspecific diversity.

scholarly journals Glacial and lake fluctuations in the area of the west Kunlun mountains during the last 45 000 years

1992 ◽  
Vol 16 ◽  
pp. 79-84 ◽  
Author(s):  
Liu Chaohai ◽  
Li Shijie ◽  
Shi Yafeng
Keyword(s):  
Lacustrine Sediments ◽  
Southern Slope ◽  
Lake Levels ◽  
Humid Climate ◽  
The West ◽  
Kunlun Mountains ◽  
West Kunlun ◽  
High Lake Levels ◽  
The Last Glacial Maximum ◽  
The Last Glacial

There appear to have been several important glacial advances on the southern slope of the west Kunlun mountains, Tibetan Plateau, since 45 000 a BP. Based on the record of alternating till and lacustrine sediments and 14C determinations, these advances are dated to 23 000–16 000, 8500–8000, and 4000–2500 a BP, and to the 16th–19th century AD, with regional variations occurring during each of the advances. The glaciation of 23 000–16 000 a BP is equivalent to the last glacial maximum (LGM) and its scope and scale were much larger than any of the others. Lake changes are a response to both tectonic uplift of the plateau and global climatic change. With regard to the latter, both changes in precipitation and changes in the extent of glaciation can affect lake levels. High lake levels occurred during interstadial conditions between 40 000 and 30 000 a BP, when the area experienced a relatively warm and humid climate, and during the LGM, between 21 000 and 15 000 a BP. During the Holocene, lakes have been shrinking gradually, coincident with the dry climate of this period of time.

scholarly journals Glacial and lake fluctuations in the area of the west Kunlun mountains during the last 45 000 years

1992 ◽  
Vol 16 ◽  
pp. 79-84 ◽  
Author(s):  
Liu Chaohai ◽  
Li Shijie ◽  
Shi Yafeng
Keyword(s):  
Lacustrine Sediments ◽  
Southern Slope ◽  
Lake Levels ◽  
Humid Climate ◽  
The West ◽  
Kunlun Mountains ◽  
West Kunlun ◽  
High Lake Levels ◽  
The Last Glacial Maximum ◽  
The Last Glacial

There appear to have been several important glacial advances on the southern slope of the west Kunlun mountains, Tibetan Plateau, since 45 000 a BP. Based on the record of alternating till and lacustrine sediments and 14C determinations, these advances are dated to 23 000–16 000, 8500–8000, and 4000–2500 a BP, and to the 16th–19th century AD, with regional variations occurring during each of the advances. The glaciation of 23 000–16 000 a BP is equivalent to the last glacial maximum (LGM) and its scope and scale were much larger than any of the others.Lake changes are a response to both tectonic uplift of the plateau and global climatic change. With regard to the latter, both changes in precipitation and changes in the extent of glaciation can affect lake levels. High lake levels occurred during interstadial conditions between 40 000 and 30 000 a BP, when the area experienced a relatively warm and humid climate, and during the LGM, between 21 000 and 15 000 a BP. During the Holocene, lakes have been shrinking gradually, coincident with the dry climate of this period of time.

Global Maps of Lake-Level Fluctuations since 30,000 yr B.P.

1979 ◽  
Vol 12 (1) ◽  
pp. 83-118 ◽  
Author(s):  
F. Alayne Street ◽  
A. T. Grove
Keyword(s):  
Lake Level ◽  
Ice Sheets ◽  
Literature Survey ◽  
Sea Surface ◽  
Lake Levels ◽  
Lake Level Fluctuations ◽  
Average Abundance ◽  
The Tropics ◽  
High Lake Levels ◽  
Precipitation And Temperature

This paper presents selected world maps of lake-level fluctuations since 30,000 yr B.P. These are based on a literature survey of 141 lake basins with radiocarbon-dated chronologies. The resulting patterns are subcontinental in scale and show orderly variations in space and time. They reflect substantial changes in continental precipitation, evaporation, and runoff, which are due to glacial/interglacial fluctuations in the atmospheric and oceanic circulations. In the tropics, high lake levels are essentially an interglacial or interstadial phenomenon, although there are important exceptions. Since extensive lakes during the Holocene corresponded with relatively high sea-surface temperatures, and therefore presumably with high evaporation rates on land, they are interpreted as the result of higher precipitation. Tropical aridity culminated in most areas at, or just after, the glacial maximum, although the present day is also characterized by a below-average abundance of surface water. In extratropical regions the mapped patterns are more complex. They vary markedly with latitude and proximity to major ice sheets. In these areas, evidence is at present insufficient to evaluate the relative contributions of precipitation and temperature to the observed lake-level record.

Holocene Fluctuations of a Meromictic Lake in Southern British Columbia

1997 ◽  
Vol 48 (1) ◽  
pp. 100-113 ◽  
Author(s):  
David J. Lowe ◽  
John D. Green ◽  
Tom G. Northcote ◽  
Ken J. Hall
Keyword(s):  
Saline Lake ◽  
Basal Layer ◽  
Climatic Changes ◽  
Depositional Environments ◽  
Laminated Sediments ◽  
Lake Depth ◽  
Lake Levels ◽  
Short Term ◽  
Northwestern North America ◽  
High Lake Levels

Holocene deposits of Mahoney Lake, a meromictic saline lake located in a closed basin in the semi-arid Okanagan Valley, contain evidence of frequent and marked changes in lake depth (up to >12 m/10014C yr) probably caused by short-term changes in effective precipitation. We studied a 5.45-m-long core comprising a basal layer of inorganic mud overlain by a succession of layers of calcareous laminated and nonlaminated organic mud, marl, and sand. We used Mazama tephra to adjust nine radiocarbon ages for the hardwater effect. Meromixis developed ca. 900014C yr B.P., and the lake has been episodically meromictic for about half the time since. Because of close linkages between sediments and depositional environments in meromictic and saline lakes, we infer that laminated sediments indicate meromictic conditions and high lake levels (>ca. 12 m water depth), whereas thick marl layers and nonlaminated sediments indicate nonmeromictic conditions and thus low lake levels (<ca. 8 m depth). Many of the inferred short-term climatic changes have not been identified in previous studies in northwestern North America, perhaps because of insensitive climatic proxies, inadequate temporal resolution, or discounting of anomalous findings.

scholarly journals Late Pleistocene lake level, glaciation and climate change in the Mongolian Altai deduced from sedimentological and palynological archives

2020 ◽  
pp. 1-22
Author(s):  
Michael Klinge ◽  
Frank Schlütz ◽  
Anja Zander ◽  
Daniela Hülle ◽  
Ochirbat Batkhishig ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Lake Level ◽  
Lacustrine Sediments ◽  
Glacial Period ◽  
Lake Levels ◽  
Apparent Contradiction ◽  
Last Glacial ◽  
Mongolian Altai ◽  
High Lake Levels ◽  
The Last Glacial

Abstract Glacial and lacustrine sediments from the Mongolian Altai provide paleoclimatic information for the late Pleistocene in Mongolia, for which only a few sufficiently studied archives exist. Glacial stages referred to global cooling events are reported for the last glacial maximum (27–21 ka) and the late glacial period (18–16 ka). Sedimentary archives from the first part of the last glacial period are infrequent. We present proxy data for this period from two different archives (88–63 and 57–30 ka). Due to the limitation of effective moisture, an increase of precipitation is discussed as one trigger for glacier development in the cold-arid regions of central Asia. Our pollen analysis from periods of high paleolake levels in small catchments indicate that the vegetation was sparse and of dry desert type between 42–29 and 17–11 ka. This apparent contradiction between high lake levels and dry landscape conditions, the latter supported by intensified eolian processes, points to lower temperatures and cooler conditions causing reduced evaporation to be the main trigger for the high lake levels during glacier advances. Rising temperatures that cause melting of glacier and permafrost ice and geomorphological processes play a role in paleolake conditions. Interpreting lake-level changes as regional or global paleoclimate signals requires detailed investigation of geomorphological settings and mountain–basin relationships.

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