Ostracod‐based reconstruction of Late Quaternary lake level changes within the Tangra Yumco lake system (southern Tibetan Plateau)

Abstract

Tangra Yumco, a large saline lake located in the central-southern part of the Tibetan Plateau, lies in a hydrologically closed basin and is part of a cascade lake system including Tangqung Co, Tangra Yumco and Xuru Co. The extension and position of this lake system makes it valuable for reconstructing palaeoclimatic variations through the lake history and to compare both with the adjacent lake systems. We reconstructed Late Quaternary lake level changes based on data from two lacustrine sediment cores. A micropalaeontological analysis focusing on Ostracoda was carried out combined with dating ( 14 C, 210 Pb, 137 Cs), sedimentology and stable isotope data from bulk sediment. Ostracod analysis involves the quantitative documentation of associations. An ostracod-based transfer function for specific conductivity was applied to assess and refine lake level changes and to compare the results with other lake level reconstructions from the Tibetan Plateau for evaluating inter-regional climatic patterns. Seven ostracod species were detected, with Leucocytherella sinensis dominating the associations followed by Leucocythere? dorsotuberosa, Limnocythere inopinata and Tonnacypris gyirongensis. Fabaeformiscandona gyirongensis, Candona candida and Candona xizangensis were found in only a few samples and at low percentages. The synthesis of ostracod-based environmental reconstruction and chronology for samples from Tangra Yumco reveals the evolution of the lake system during the past 17 ka. A low lake level around 17 cal ka BP is followed by a recovering until the reaching of a high stand around 8-9 cal ka BP. Subsequently, between 7.7 and 2.5 cal ka BP, it remained relatively stable with a subsequent short-living lowstand-highstand cycle at around 2 ka. Thereafter, the ostracod-based conductivity transfer function shows an increase of conductivity corresponding to a lake level rising phase at around 0.4 ka. The recorded changes are indicators of past climatic conditions and refine the palaeoclimatic models in this area. Figure 2. Composite profile (without turbiditic layers) of the two cores with age-depth model and sedimentation rates as published by Henkel et al. (2016).

A Late Miocene – Early Pliocene Paratethyan Type Ostracod Fauna From the Denizli Basin (Sw Anatolia) and Its Palaeogeographic Implications

“…Moreover, they are easily preserved in the sedimentary archives of Pontocaspian basins, allowing the reconstruction of the palaeoenvironment they once dwelt in. A number of studies have used ostracod assemblages to redraw limnological conditions in a large spectrum of lake environments (De Deckker and Forester, 1988;Martens, 1994;Boomer et al, 1996;Horne et al, 2002;De Deckker and Lord, 2017;Alivernini et al, 2018;Rausch and Stoica, 2019). The Denizli Basin in SW Anatolia (Turkey) ( Fig.…”

Introductory Chapter: An Introduction to the Stratigraphic Setting of Paleozoic to Miocene Deposits Based on Paleoecology, Facies Analysis, Chemostratigraphy, and Chronostratigraphy - Concepts and Meanings

“…The high resolution chronostratigraphy of the paleo-lakes is a main research topic, which has been deeply studied by several authors [17][18][19][20][21][22][23][24][25][26][27]. In particular, the Ibate paleolake has shown a distal lacustrine environment with low-oxygen conditions in its bottom waters [17].…”

“…An age model was constructed based on radiocarbon dating, allowing to interpret the environmental changes during the Late Glacial and the post-glacial [21]. Another representative paleolake is the Tangra Yumco, represented by a wide saline paleolake located on the Tibetan Plateau, which has been recently studied as a valuable example in order to reconstruct the climatic variations [23]. Micropaleontologic and sedimentologic data have been integrated with isotopic stratigraphy.…”

“…Micropaleontologic and sedimentologic data have been integrated with isotopic stratigraphy. Integrated stratigraphic information has allowed to reconstruct the geologic evolution of the paleolake during the last 17 ky [23]. The lake level was low at 17 ky BP, followed by a highstand phase at 8-9 ky BP.…”

ICDP workshop on scientific drilling of Nam Co on the Tibetan Plateau: 1 million years of paleoenvironmental history, geomicrobiology, tectonics and paleomagnetism derived from sediments of a high-altitude lake

“…During the past 10 years, transect studies focusing on paleoclimate on the Tibetan Plateau, including Nam Co, have been carried out (Ahlborn et al, 2017;Alivernini et al, 2018;Dietze et al, 2014). In addition, physical and chemical limnological seasonal processes as well as climate parameters at Nam Co have been monitored.…”