Early to mid-Holocene lake high-stand sediments at Lake Donggi Cona, northeastern Tibetan Plateau, China

Abstract

19Lake high-stand sediments are found in three onshore terraces at Lake Donggi Cona, north-eastern 20Tibetan Plateau, and reveal characteristics of hydrological changes on lake shorelines triggered by 21 climate change, geomorphological processes, and neo-tectonic movements. The terraces consist of 22 fluvial, alluvial to littoral-lacustrine facies. End-member modeling of grain size distributions allowed 23 quantification of sediment transport processes and relative lake levels during times of deposition. 24Radiocarbon dating revealed higher than modern lake levels during the early and mid-Holocene. Lake 25 levels follow the trend of Asian monsoon dynamics, and are modified by local non-climatic drivers. 26Site-specific impacts explain fluctuations during the initial lake level rise ~11 cal ka BP. Maximum lake 27 extension reached ~9.2 cal ka BP, at ~16.5 m above present lake level (a.p.l.l.). Littoral and lacustrine 28 sediment deposition paused during a phase of fluvial activity and post-depositional cryoturbations at 29 ~8.5 cal ka BP, when the lake level fell to ~8 m a.p.l.l. After a second maximum at ~7.5 cal ka BP, lake 30 level declined slightly at ~6.8 cal ka BP, probably due to a non-climatic pulse that caused lake 31 opening. The level remained high until a transition towards drier conditions of ~4.7 cal ka BP. Though 32 discontinuous, high-stand sediments provide a unique, high-resolution archive.

Lake Qinghai sediment geochemistry linked to hydroclimate variability since the last glacial

“…During this deglacial period, the lake did not desiccate completely (Thomas et al, 2014) and was occupied occasionally by shallow water, in particular, during the B/A warm period. Wet conditions during the B/A warm period were also recorded by other nearby lake sediments, such as in Lakes Luanhaizi and Donggi Cona (Herzschuh et al, 2010;Dietze et al, 2013;Wang et al, 2014). The alternations of wet and dry periods are also reflected by fluctuating TOC, grain size, %CaCO 3 , and discontinuous preservation of ostracod shells (Fig.…”

“…Likewise, a high-resolution fossil pollen record from sedimentary cores at Barkol Lake (eastern Xinjiang) indicates that the lake was dried up until 8.9 ka (Tao et al, 2010). Similar to Lake Qinghai, a shift to lacustrine precipitates in Zhuyeze and Donggi Cona Lakes occurred at the beginning of the Holocene (Long et al, 2010;Dietze et al, 2013). It appears that, during the last glacial period, all these lake basins largely served as dust sinks.…”

Early to Mid-Holocene Lake High-Stand Sediments at Lake Donggi Cona, Northeastern Tibetan Plateau, China – Comment to the Paper Published by Dietze et al., Quaternary Research 79 (2013), 325-336

“…Dietze et al (2013) recently reported on the formation and age of deposits in the vicinity of Lake Donggi Cona regarded as lake high-stand sediments. They investigated sediments exposed as terraces at nine section sites near the lake.…”

“…Fine-grained carbonate-rich sediments of their Facies I were interpreted as lake sediments accumulated "below the wavedominated zone". Radiocarbon age data for the sediments of the sections were used for the reconstruction of higher lake levels of Donggi Cona in the early and mid-Holocene and the inference of low levels after~4700 cal yr BP (Dietze et al, 2013).…”

“…A single shell of Leucocythere dorsotuberosa was recorded in section P14 at 28 cm (not shown). Lithology simplified following Dietze et al (2013): fine-grained platy sediments regarded as lake sediments at the base and between 131 and 22 cm, low-energy fluvial/alluvial sediments in between, and soil on top. …”