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

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.

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Contrasting Patterns in Abrupt Asian Summer Monsoon Changes in the Last Glacial Period and the Holocene

Paleoceanography and Paleoclimatology ◽

10.1002/2017pa003294 ◽

2018 ◽

Vol 33 (2) ◽

pp. 214-226 ◽

Cited By ~ 5

Author(s):

Dianbing Liu ◽

Yongjin Wang ◽

Hai Cheng ◽

R. L. Edwards ◽

Xinggong Kong ◽

...

Keyword(s):

Summer Monsoon ◽

Asian Summer Monsoon ◽

Glacial Period ◽

Last Glacial Period ◽

The Holocene ◽

Last Glacial ◽

Asian Summer ◽

The Last Glacial

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Potential influence of temperature changes in the Southern Hemisphere on the evolution of the Asian summer monsoon during the last glacial period

Quaternary International ◽

10.1016/j.quaint.2015.05.068 ◽

2016 ◽

Vol 392 ◽

pp. 239-250 ◽

Cited By ~ 18

Author(s):

Li-Yin Han ◽

Ting-Yong Li ◽

Hai Cheng ◽

R. Lawrence Edwards ◽

Chuan-Chou Shen ◽

...

Keyword(s):

Southern Hemisphere ◽

Summer Monsoon ◽

Asian Summer Monsoon ◽

Glacial Period ◽

Potential Influence ◽

Last Glacial Period ◽

Temperature Changes ◽

Influence Of Temperature ◽

Asian Summer ◽

The Last Glacial

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

Biogeosciences ◽

10.5194/bg-16-2095-2019 ◽

2019 ◽

Vol 16 (10) ◽

pp. 2095-2114 ◽

Cited By ~ 2

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.

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Causes and climatic influence of centennial-scale denitrification variability in the southeastern Arabian Sea since the last glacial period

Quaternary Research ◽

10.1017/qua.2020.118 ◽

2021 ◽

pp. 1-13

Author(s):

Sidhesh Nagoji ◽

Manish Tiwari

Keyword(s):

Arabian Sea ◽

Asian Summer Monsoon ◽

Intermediate Water ◽

Glacial Period ◽

South Asian Summer Monsoon ◽

Last Glacial Period ◽

The Holocene ◽

Last Glacial ◽

Southeastern Arabian Sea ◽

The Last Glacial

Abstract Denitrification occurring in the oxygen minimum zone of the Arabian Sea produces nitrous oxide, a powerful greenhouse gas. Therefore, it is important to understand the mechanisms controlling denitrification's intensity and evaluate its influence on the global climate at various timescales. We studied multiple geochemical and isotopic proxies in a sediment core from the southeastern Arabian Sea (SEAS) at a high (centennial-scale) resolution. We find that since the last glacial period, both the ventilation and the productivity caused by the South Asian summer monsoon played a major role in controlling the denitrification variability in SEAS. During the Last Glacial Maximum (LGM) and since the Holocene, denitrification increased in SEAS despite reduced monsoon-induced productivity. During the LGM, weakened thermohaline circulation resulted in reduced ventilation of the intermediate waters of SEAS, causing increased denitrification. During the Holocene, the increase in denitrification is caused by an enhanced inflow of oxygen-depleted Red Sea and Persian Gulf waters into the intermediate depth of SEAS owing to a rising sea level that prohibited ventilation by the Antarctic Intermediate Water. We further find millennial-scale synchronicity between denitrification in SEAS, global monsoons, and the North Atlantic climate, implying systematic linkages via greenhouse gases abundance.

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Southern Hemisphere imprint for Indo-Asian summer monsoons during the last glacial period as revealed by Arabian Sea productivity records

Biogeosciences ◽

10.5194/bg-10-7347-2013 ◽

2013 ◽

Vol 10 (11) ◽

pp. 7347-7359 ◽

Cited By ~ 15

Author(s):

T. Caley ◽

S. Zaragosi ◽

J. Bourget ◽

P. Martinez ◽

B. Malaizé ◽

...

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Arabian Sea ◽

Asian Monsoon ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

Asian Summer ◽

Asian Monsoons ◽

The Last Glacial

Abstract. The monsoon is one of the most important climatic phenomena: it promotes inter-hemispheric exchange of energy and affects the economical prosperity of several countries exposed to its seasonal seesaw. Previous studies in both the Indian and Asian monsoon systems have generally suggested a dominant northern hemispheric (NH) control on summer monsoon dynamics at the scale of suborbital–millennial climatic changes, while the forcing/response of Indian and Asian monsoons at the orbital scale remains a matter of debate. Here, six marine sediment cores distributed across the whole Arabian Sea are used to build a regional surface marine productivity signal. The productivity signal is driven by the intensity of Indian summer monsoon winds. Our results demonstrate the existence of an imprint of suborbital southern hemispheric (SH) temperature changes (i.e. Antarctica) on the Indian summer monsoon during the last glacial period that is generally not recognized. During the last deglaciation, the NH played a more significant role. This suggests that fluctuations in the Indian monsoon are better explained in a bipolar context. The δ18O signal recorded in the Asian monsoon speleothem records could be exported by winds from the Indian summer monsoon region, as recently proposed in modelling exercise, explaining the SH signature observed in Asian cave speleothems. Contrary to the view of a passive response of Indian and Asian monsoons to NH anomalies, the present results appear to suggest that the Indo-Asian summer monsoon plays an active role in amplifying millennial inter-hemispheric asymmetric patterns. Additionally, this study confirms previously observed differences between Indian and Asian speleothem monsoonal records at the orbital-precession scale.

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Changes of Clay Mineral Assemblages in the Northern Part of the Aleutian Basin in the Bering Sea during the Last Glacial Period

Journal of the Mineralogical Society of Korea ◽

10.9727/jmsk.2011.24.1.019 ◽

2011 ◽

Vol 24 (1) ◽

pp. 19-29 ◽

Cited By ~ 1

Author(s):

Sung-Han Kim ◽

Hyen-Goo Cho ◽

Boo-Keun Khim

Keyword(s):

Clay Mineral ◽

Bering Sea ◽

Glacial Period ◽

Last Glacial Period ◽

Last Glacial ◽

Mineral Assemblages ◽

Aleutian Basin ◽

The Bering Sea ◽

The Last Glacial

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

10.5194/bg-2018-476 ◽

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.

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

10.5194/egusphere-egu2020-8414 ◽

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

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 Homo sapiens 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).&#160;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.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 Amphora spp., Halamphora spp. and Nitzschia spp. In phases of lake-level high stands of Lake Lisan, the diatom flora shifts towards a more plankton-dominated freshwater flora containing Aulacoseira spp. and taxa from the Cyclotella-ocellata-species complex.

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