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.

CLIMATE@COA project: Climate and human adaptation during the Last Glacial Period in the Côa Valley region (Portugal)

2021 ◽  
Author(s):  
Luca Dimuccio ◽  
Thierry Aubry ◽  
Lúcio Cunha ◽  
Nelson Rodrigues
Keyword(s):  
Late Pleistocene ◽  
Interdisciplinary Approach ◽  
Evolutionary Model ◽  
Depositional Environments ◽  
Glacial Period ◽  
Upper Palaeolithic ◽  
Last Glacial Period ◽  
Last Glacial ◽  
North East ◽  
The Last Glacial

<p>In Portugal, climate fluctuations of Late Pleistocene are well-known from marine record on the western Iberian continental margin, particularly of Marine Isotope Stages 4, 3 and 2, and they include various events of secular abrupt climate changes. During cooling phases the Heinrich Events (HE) occurred, corresponding to episodes of massive ice-discharges from Northern Hemisphere ice sheets. Furthermore, several climate phases with relatively warmer conditions, known as Dansgaard-Oeschger (D-O) cycles, characterized by an abrupt warming (D-O event) followed by a more gradual cooling, took place in-between HE. This pronounced climate instability that characterizes the Last Glacial Period between ca. 80-12 ka is recorded in a variety of marine and terrestrial archives worldwide. It had a recognized impact on the bioclimatic zones and, possibly, on the Neanderthal and Anatomically Modern Human (AMH) settlements of Iberia.</p><p>Based mainly on the study of geoarchaeological records preserved in caves and rock-shelters of Iberia, a correlation framework with climate shifts has been proposed to explain the observed discontinuities between sequences containing late Middle and early Upper Palaeolithic remains. Moreover, a climate driven model has been advanced to explain the chronological differences between northern and southern Pyrenean data by a later dispersion of AMH and the persistence of last Neanderthals in Southern Iberia, which were interpreted as a direct impact of HE4 (40-38 ka) in the distribution of large ungulate populations.</p><p>Despite all these data, the exact impact of HE on terrestrial systems, the evaluation of the latitudinal differentiation of their impact and time-gap, as well as the correlation between periods of relative stabilization/soil formation and the D-O events remain to be clearly established. In addition, the whole framework relating to the Middle-to-Upper Palaeolithic transition has been excessively dependent on karst archives and it should be investigated in other geomorphological settings - among these the fluvial and Iberian plateau (“Meseta”), both present in the Côa Valley region (Douro Basin, north-east of Portugal). Alluvial and colluvial deposits preserved in the Côa Valley (e.g. at the Cardina-Salto do Boi, Quinta da Barca Sul, Penascosa, Fariseu, Olga de Ervamoira sites) have demonstrated to be a valuable record of information about Late Pleistocene sedimentary processes, depositional environments, and hunter-gatherer’s behaviour at local and regional scales.</p><p>In this context, the CLIMATE@COA project (COA/CAC/0031/2019), funded by the Fundação para a Ciência e Tecnologia (FCT), proposes an integrated multi/interdisciplinary approach based on the stratigraphical, sedimentological, geochemical, geomorphological, geoarchaeological, and geochronological analyses of terrestrial record (natural and cultural) preserved in the Côa Valley and surrounding plateau areas, with the aim to develop an evolutionary model for the region and to deduce the environmental forcing factors for such evolution - namely climate and ecosystem changes. In addition, the project’s data will allow to define better the chronology of the transition between Neanderthal and AMH and to infer on land use and social organization in its environmental context.</p>

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.

scholarly journals Supplemental Material: Thermodynamic evaporation and freshwater mixing models to test salinity proxies for late Pleistocene lake levels, Mono Lake, California

2021 ◽  
Author(s):  
Rahul Sahajpal
Keyword(s):  
Late Pleistocene ◽  
Computer Code ◽  
Mono Lake ◽  
Geochemical Evolution ◽  
Mixing Models ◽  
Glacial Period ◽  
Lake Levels ◽  
Last Glacial Period ◽  
Lake Waters ◽  
The Last Glacial

A Python-based computer code used for automating the simulation used to predict the geochemical evolution of Mono Lake waters since the last glacial period.<br>

scholarly journals Ostracods as ecological and isotopic indicators of lake water salinity changes: the Lake Van example

2019 ◽  
Vol 16 (10) ◽  
pp. 2095-2114 ◽  
Author(s):  
Jeremy McCormack ◽  
Finn Viehberg ◽  
Derya Akdemir ◽  
Adrian Immenhauser ◽  
Ola Kwiecien
Keyword(s):  
Lake Water ◽  
Lake Level ◽  
Water Salinity ◽  
Glacial Period ◽  
Lake Van ◽  
Faunal Assemblage ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Hydrological Changes ◽  
The Last Glacial

Abstract. Ostracods are common lacustrine calcitic microfossils. Their faunal assemblage and morphological characteristics are important ecological proxies, and their valves are archives of geochemical information related to palaeoclimatic and palaeohydrological changes. In an attempt to assess ostracod ecology (taxonomic diversity and valve morphology) combined with valve geochemistry (δ18O and δ13C) as palaeosalinity indicators, we analysed sedimentary material from the International Continental Scientific Drilling Program (ICDP) Ahlat Ridge site from a terminal and alkaline lake, Lake Van (Turkey), covering the last 150 kyr. Despite a low species diversity, the ostracod faunal assemblage reacted sensitively to changes in the concentration of total dissolved salts in their aquatic environment. Limnocythere inopinata is present throughout the studied interval, while Limnocythere sp. A is restricted to the Last Glacial period and related to increased lake water salinity and alkalinity. The presence of species belonging to the genus Candona is limited to periods of lower salinity. Valves of Limnocytherinae species (incl. L. inopinata) display nodes (hollow protrusions) during intervals of increased salinity. Both the number of noded valves and the number of nodes per valve appear to increase with rising salinity, suggesting that node formation is related to hydrological changes (salinity and/or alkalinity). In contrast to Lake Van's bulk δ18O record, the δ18O values of ostracod valves do record relative changes of the lake volume, with lower values during high lake level periods. The δ13C values of different species reflect ostracod habitat preferences (i.e. infaunal vs. epifaunal) but are less sensitive to hydrological changes. However, combined with other proxies, decreasing Holocene δ13C values may indicate a freshening of the lake water compared to the low lake level during the Last Glacial period. The Lake Van example underscores the significance and value of coupling ostracod ecology and valve geochemistry in palaeoenvironmental studies of endorheic lake basins.

Late Pleistocene and Early Holocene aeolian deposits of Tasmania and their climatic implications

2020 ◽  
pp. 1-24
Author(s):  
Peter D. McIntosh ◽  
Christina Neudorf ◽  
Olav B. Lian ◽  
Adrian J. Slee ◽  
Brianna Walker ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Cold Climate ◽  
Sediment Supply ◽  
Early Holocene ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Aeolian Deposits ◽  
Semi Arid ◽  
The Last Glacial

Abstract Late Pleistocene and Early Holocene aeolian deposits in Tasmania are extensive in the present subhumid climate zone but also occur in areas receiving >1000 mm of rain annually. Thermoluminescence, optically stimulated luminescence, and radiocarbon ages indicate that most of the deposits formed during periods of cold climate. Some dunes are remnants of longitudinal desert dunes sourced from now-inundated continental shelves which were previously semi-arid. Others formed near source, often in the form of lunettes east of seasonally-dry lagoons in the previously semi-arid Midlands and southeast of Tasmania, or as accumulations close to floodplains of major rivers, or as sandsheets in exposed areas. Burning of vegetation by the Aboriginal population after 40 ka is likely to have influenced sediment supply. A key site for determining climate variability in southern Tasmania is Maynes Junction which records three periods of aeolian deposition (at ca. 90, 32 and 20 ka), interspersed with periods of hillslope instability. Whether wind speeds were higher than at present during the last glacial period is uncertain, but shells in the Mary Ann Bay sandsheet near Hobart and particle size analysis of the Ainslie dunes in northeast Tasmania suggest stronger winds during the last glacial period than at present.

scholarly journals Ostracods as ecological and isotopic indicators of lake water salinity changes: The Lake Van example

2019 ◽  
Author(s):  
Jeremy McCormack ◽  
Finn Viehberg ◽  
Derya Akdemir ◽  
Adrian Immenhauser ◽  
Ola Kwiecien
Keyword(s):  
Lake Water ◽  
Lake Level ◽  
Water Salinity ◽  
Glacial Period ◽  
Lake Van ◽  
Faunal Assemblage ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Hydrological Changes ◽  
The Last Glacial

Abstract. Ostracods are common lacustrine calcitic microfossils. Their faunal assemblage and morphological characteristics are important ecological proxies, while their valves are archives of geochemical information related to palaeoclimatic and palaeohydrological changes. In an attempt to assess ostracod ecology (taxonomic diversity and valve morphology) combined with valve geochemistry (δ18O and δ13C) as palaeosalinity indicators, we analysed material from terminal and alkaline Lake Van (Turkey) covering the last 150 kyr. Despite a low species diversity, the ostracod faunal assemblage reacted sensitive to changes in the concentration of total dissolved salts in their aquatic environment. Limnocythere inopinata is present throughout the studied interval, while Limnocythere sp. A is restricted to the Last Glacial period and related to increased lake water salinity and alkalinity. The presence of species belonging to the genus Candona is limited to periods of lower salinity. Valves of limnocytherinae species (incl. L. inopinata) display nodes (hollow protrusions) during intervals of increased salinity. Both the amount of noded valves and the number of nodes per valve appear to increase with rising salinity, suggesting that node formation is related to hydrological changes (salinity and/or alkalinity). In contrast to Lake Van's inorganic δ18O record, the δ18O values of ostracod valves do record relative changes of the lake volume, with lower values during high lake level periods. The δ13C values of different species reflect ostracod habitat preferences (i.e., infaunal versus epifaunal) but are less sensitive to hydrological changes. However, combined with other proxies, decreasing Holocene δ13C values may indicate a freshening of the lake water compared to the low lake level during the Last Glacial period. The Lake Van example underscores the significance and value of coupling ostracod ecology and valve geochemistry in palaeoenvironmental studies of endorheic lakes basins.

scholarly journals Supplemental Material: Thermodynamic evaporation and freshwater mixing models to test salinity proxies for late Pleistocene lake levels, Mono Lake, California

2021 ◽  
Author(s):  
Rahul Sahajpal
Keyword(s):  
Late Pleistocene ◽  
Computer Code ◽  
Mono Lake ◽  
Geochemical Evolution ◽  
Mixing Models ◽  
Glacial Period ◽  
Lake Levels ◽  
Last Glacial Period ◽  
Lake Waters ◽  
The Last Glacial

A Python-based computer code used for automating the simulation used to predict the geochemical evolution of Mono Lake waters since the last glacial period.<br>

scholarly journals Mineralogical Record for Stepwise Hydroclimatic Changes in Lake Qinghai Sediments Since the Last Glacial Period

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 963
Author(s):  
Yougui Song ◽  
Xiulan Zong ◽  
Linbo Qian ◽  
Huifang Liu ◽  
Jibao Dong ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Lake Level ◽  
East Asian Monsoon ◽  
Asian Summer Monsoon ◽  
Glacial Period ◽  
Lake Qinghai ◽  
Last Glacial Period ◽  
Last Glacial ◽  
Mineral Assemblages ◽  
The Last Glacial

Lake Qinghai is sensitive to climatic changes because of its pivotal location between mid-latitude Westerlies and the low-latitude East Asian monsoon. An 18.6 m long drilling core (1Fs) from Lake Qinghai provides new information on the hydroclimatic dynamics since the last glacial period. Here, we present the results of bulk mineral assemblages of this core. X-ray diffraction (XRD) results showed that the bulk minerals of the core sediments consist of major clastic minerals (e.g., quartz, feldspar, muscovite), carbonates (e.g., calcite, aragonite, dolomite), and minor clay minerals (e.g., chlorite). Quartz as an exogenous detrital mineral in lake sediments, its abundance is related to lake level changes resulting from regional climate changes via fluvial/aeolian transportation. Aragonite was precipitated from water solutions or chemical alteration of pre-existing minerals or biogenic mediation, closely related to lake hydroclimate change. Mineral assemblages revealed remarkable stepwise hydroclimatic changes. High quartz content and low calcite without aragonite suggested a cold-wet climate condition under predominant westerlies during the last glacial period from 35 to 25.3 ka. Afterward, quartz decreased and aragonite occasionally appeared, indicating an unstable hydroclimatic condition during the last deglaciation. Since the Early Holocene (11.9–8.2 ka), predominant minerals shifted from terrigenous quartz to authigenic carbonates, suggesting an increasing lake level, possibly due to intensified Asian summer monsoon with increased effective moisture. Aragonite became the primary carbonate mineral, implying a warming and humid hydroclimate environment with a relatively higher lake-level. During the Middle Holocene (8.2–4.2 ka), aragonite showed a decreasing trend indicating a higher lake level with weak evaporation. During the Late Holocene since 4.2 ka, there were lower quartz and aragonite, suggesting a deep lake with a weak summer monsoon. Our quartz and carbonate minerals record provided essential clues to reconstruct hydroclimate change in Lake Qinghai since the last glacial period.

The diatom flora of Lake Lisan (Israel): a preliminary investigation

2020 ◽  
Author(s):  
Hannah Hartung ◽  
Jane M. Reed ◽  
Thomas Litt
Keyword(s):  
Lake Level ◽  
Eastern Mediterranean ◽  
Sediment Cores ◽  
Dead Sea ◽  
Glacial Period ◽  
Last Glacial Period ◽  
Diatom Flora ◽  
Last Glacial ◽  
The Dead ◽  
The Last Glacial

&lt;p&gt;The Eastern Mediterranean, and the southern Levant in particular, is a key region for palaeoclimatological and palaeoenvironmental research due to its highly complex topography and climatic variability. Our understanding of environmental variability and its possible drivers, and the interaction with migration processes of modern &lt;em&gt;Homo sapiens&lt;/em&gt; from a source area in Africa to Europe, is still limited. This is partly because continuous sediment records of sufficient age are rare across the Mediterranean Basin. The deposits of the Dead Sea represent an ideal archive to investigate palaeoenvironmental conditions during human migration phases in the Last Glacial period (MIS 4-2).&amp;#160;&lt;/p&gt;&lt;p&gt;Diatoms (single-celled siliceous algae, Bacillariophyceae) have well-recognised potential to generate high-quality palaeolimnological data, especially in closed-basin saline lakes, but they remain one of the least-exploited proxies in Eastern Mediterranean palaeoclimate research. Here, we present preliminary results of a low-resolution diatom study derived from analysis of sediment deposits of Lake Lisan, the last glacial precursor of the Dead Sea. Sediment cores were recovered during an ICDP campaign in 2010/2011 from the centre of the modern Dead Sea. 18 sediment samples were analysed to investigate (a) the preservation of diatom valves in various evaporitic deposits (b) possible shifts in diatom species composition of Lake Lisan during the Last Glacial period, and (c) if diatoms can be used as proxy indicator for lake-level and, thus, palaeoclimate reconstruction. We focus on a prominent lake-level high stand of Lake Lisan at around 28-22 ka BP, which resulted in the merging Lake Lisan and freshwater Lake Kinneret.&lt;/p&gt;&lt;p&gt;First results show that the diatom preservation is exceptionally good in evaporitic deposits of the sediment cores from Lake Lisan, which is contradictory to the available literature. In contrast to Holocene deposits from the Dead Sea, diatoms are abundant in all analysed samples from laminated deposits from Lake Lisan: the diatom flora is dominated by halophilous benthic diatoms, such as &lt;em&gt;Amphora&lt;/em&gt; spp., &lt;em&gt;Halamphora&lt;/em&gt; spp. and &lt;em&gt;Nitzschia&lt;/em&gt; spp. In phases of lake-level high stands of Lake Lisan, the diatom flora shifts towards a more plankton-dominated freshwater flora containing &lt;em&gt;Aulacoseira&lt;/em&gt; spp. and taxa from the &lt;em&gt;Cyclotella-ocellata-&lt;/em&gt;species complex.&lt;/p&gt;

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