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Global warming over the past decades has resulted in desiccation of lakes in arid and semi-arid northern China. However, the mechanisms responsible for the sharp fluctuations in water levels for these lakes in this region are still unclear. The water level fluctuations in geological time can provide an analogue to better understand current lake levels' response to global warming. In this study, a combination of quartz and feldspar luminescence dating techniques was applied to establish the chronologies of two sedimentary sequences related to lake level in the catchment of Daihai Lake, located on the fringe of the East Asian summer monsoon (EASM) domain. Our objective is to reconstruct the late Quaternary history of lake level fluctuations and provide the interpretations of their causes. The results indicate that two lake-level highstands existed during 130–120 ka and 8-4 ka, at least ∼38 m and 40 m above the current lake level, respectively. We interpret that the lake level variations on multiple timescales in the monsoonal marginal area have primarily been regulated by the EASM intensity and corresponding monsoonal precipitation, while temperature changes may have played a minor role. Moreover, a compilation of existing lake level data reveals that EASM intensity has a complex response to changes in Northern Hemisphere summer insolation on millennial-orbital timescales. Combining precipitation records in central and southern China, the character of rainfall across East Asia during MIS 5 exhibits a dominant tripolar pattern. • Lake highstands existed during 130–120 ka (MIS 5) and 8-4 ka (MIS 1). • EASM intensity has a complex response to changes in Northern Hemisphere summer insolation on millennial-orbital timescales. • The character of rainfall across East Asia exhibits a dominant triple pattern during MIS 5. [ABSTRACT FROM AUTHOR]

The palaeo-shorelines around the lakes on the Tibetan Plateau can be used to reconstruct water level variations, which serve as sensitive indicators of hydroclimate change. Extensive studies have been carried out to constrain the Holocene lake level fluctuations by dating shorelines with a variety of methods (e.g., luminescence, 14C, 10Be and U–Th series). In comparison, the timing of the lake level variations during the last glacial and subsequent deglaciation periods has been rarely studied. The driving factors of such changes, therefore, remain elusive. In this study, we performed a detailed luminescence dating investigation on six samples taken from a nearshore sedimentary outcrop in the south of Selin Co basin. The post-IR IRSL signals measured at 225 °C (pIRIR 225) on sand-sized K-feldspar grains demonstrated a generally good behavior and yielded reliable chronologies, while the optically stimulated luminescence (OSL) signals of quartz showed systematical age underestimation, which was attributed to anomalous fading. Six pIRIR 225 ages ranging from 15 to 10 ka suggested that the lake level of Selin Co during the last deglaciation reached up to 40–45 m high above the modern lake level. In view of the regional precipitation and temperature proxy records, we consider that the glacier meltwater supply has likely been the primary contributor to the lake highstands during the last deglaciation. [ABSTRACT FROM AUTHOR]

Lakes over the inner Tibetan Plateau (TP) are very sensitive to the regional environmental transformations and climate changes. Well-preserved lake sediments around these lakes provide critical geomorphological and sedimentary evidence that can be used to infer the past hydroclimate changes. In this study, a lacustrine section from a sandy shoreline (∼74 m above the modern lake) situated to the northwest of modern Dawa Co in the inner TP was investigated using both luminescence and radiocarbon dating methods. Our results demonstrated: (1) the quartz optically simulated luminescence (OSL) dating yielded much younger ages (∼4 ka) than that of the post-infrared IRSL (pIRIR) dating of the K-feldspar fraction; (2) fading test showed g-values ranging between 1.34 and 4.46%/decade for quartz OSL signals, which is considered to be responsible for the underestimation of the corresponding ages; (3) the AMS 14C age of the charcoal sample from the section is in line with the K-feldspar pIRIR 225 ages, confirming the reliability of the pIRIR 225 dates and the underestimation of the quartz OSL ages. The anomalous fading of quartz OSL signals and the consequent age underestimation have been reported in several other lakes on the TP, we presented here for the first time firm evidence of the phenomenon with the help of a robust independent control of AMS 14C age of the charcoal. Based on the pIRIR 225 and AMS 14C ages, we conclude that Dawa Co underwent a prominent highstand during the early Holocene (∼9–7 ka), which was probably controlled by the large amounts of glacial meltwater input and the increased monsoonal precipitation. [ABSTRACT FROM AUTHOR]

Over the Tibetan Plateau (TP), lakes as paleoenvironmental archives have been the most extensively investigated for their sensitivities to climate change on different timescales. Well-preserved shoreline and terrace remains surrounding these lakes provide critical geomorphological and sedimentary evidence that can be used to infer past lake levels over geological timescales. These features can offer an analogue for understanding how future lake-levels respond to global warming. In this study, we investigated a series of water level-related depositional profiles around the Selin Co basin from the central TP, by dating 28 samples using K-feldspar luminescence techniques. Combining the obtained chronological data with sedimentological, stratigraphic evidence and differential GPS survey observations, the Holocene history of lake-level fluctuations in Selin Co was inferred. The results show a stable highstand between 10 ka and 7 ka but a striking subsequent lake-level decline. This pattern appears to follow the solar insolation-forced changes in the intensity of the Indian summer monsoon (ISM), particularly during the early Holocene. However, such gradual weakening of ISM intensity after the early Holocene may not interpret the dramatically rapid shrinking of Selin Co, implying other components are largely underrecognized driving factors accounting for the effective moisture of lakes in the early Holocene. Here, we argue that the increased meltwater input from glaciers and permafrost, together with increased precipitation, might have resulted in the high lake level at 10–7 ka, as the high summer temperature during the early Holocene induced massive melting water flow into the lake. By 7 ka, the abrupt lake-level drop is likely related to the decreased meltwater owing to decreasing regional temperatures documented from glacier landforms, ice cores and lacustrine sediments. Therefore, we highlight that meltwater from glaciers and permafrost poured into lakes on the central TP, particularly during warm periods on the millennial timescales, might also dominate the Holocene high lake levels. • Holocene lake-level history of Selin Co built using K-feldspar luminescence dating method. • The lake level experienced highstand between at 10–7 ka but a striking decline afterward. • Monsoonal rainfall might not be unique factor driving Holocene lake evolution. • Glacial meltwater highlighted as key influence on lake-levels. [ABSTRACT FROM AUTHOR]

Numerous studies have documented the sedimentary sequences of the Yangtze Delta in response to relative sea-level changes since the Last Glacial Maximum (LGM). However, the pre-LGM sedimentary history of the paleo-Yangtze Delta remains unknown, especially for the formation timing of the basal fluvial sedimentary succession in the paleo-Yangtze incised valley. Here, based on luminescence dating techniques, the sedimentary stratigraphy of three sediment cores (YD016, YD014 and YD006) were constrained and the sedimentary successions were analyzed. Combining with previously published sedimentary sequences, we infer spatiotemporal variation of the stratigraphic architectures over the Yangtze Delta through the time spanning from the late Pleistocene to the Holocene (∼50–0 ka). Our reconstruction for the paleogeography and environmental evolution of the paleo-Yangtze incised valley showed that the basal fluvial channel belts in the paleovalley associated with coeval laterally extensive paleosol-bearing stratigraphy at the interfluves occurred in the transition between marine isotope stage (MIS) 3 and MIS 2; the overlying sedimentary successions are characterized by the post-glacial floodplain deposits formed between 19 and 12 ka, and estuary to shallow marine deposits during early Holocene (11–8 ka); and then the upper most is the Yangtze Delta depositional systems dated to mid-to-late Holocene (since ∼8 ka). Correlations of the chronostratigraphy of sediment cores over the cross-sections in this region suggest that a superimposed compound fluvial channel complex has probably characterized the paleo-Yangtze incised valley systems since MIS 3. Apart from the post-LGM infilling of the LGM incised valley, the basal MIS 3 fluvial deposits might represent the earlier infilling over another incised valley, which might be formed during MIS 4 although our cores have not reached yet. Such hierarchical incised valley systems in the paleo-Yangtze Delta were likely related to the late Quaternary sea-level changes. In addition, the relict inherited topography since the last glacial period could have played an important role in the stacking patterns of the paleo-Yangtze incised valleys. • Luminescence ages constrained the basal fluvial deposits of the Yangtze incised valley in MIS3/2 • The paleo-Yangtze incised-valley complex might be existed in MIS 3 and lasted until to MIS 2 • A superimposed compound fill pattern probably have occurred in the Yangtze valley since MIS 3. • The hierarchical incised valley systems and inherited topography should be considered for the paleo-Yangtze Delta evolution. [ABSTRACT FROM AUTHOR]

Coastal deposits are ideal archives to decipher the history of terrestrial-marine interactions in response to sea-level changes. Over the last decades, numerous investigations have been implemented to uncover the stratigraphic framework and the paleoenvironment evolution of the Jiangsu coastal plain (JCP), China. However, there have been limited studies on the sedimentary history over the glacial-interglacial timescales because of the lack of reliable chronostratigraphy. Here, we selected a 30-m-long sediment core in the northern JCP for luminescence dating, and carried out comprehensive sedimentological and paleontological analyses to ascertain the sedimentary history. Multiple luminescence dating techniques, including quartz optically-stimulated luminescence (OSL) and feldspar (polymineral) post-infrared (IR) IR stimulated luminescence (pIRIR) dating, were applied to determine the chronology of the sediment core. The obtained chronostratigraphy of core JCP01 spanning ~130 ka reveals that terrestrial deposition occurred in Marine Isotope Stage (MIS) 6, MIS 4–2 and the late stage of MIS 1. In contrast, marine influenced deposition is identified in MIS 5e and early MIS 1. The terrestrial interval of core JCP01 mainly consists of stiff clay and floodplain facies occurring at depths of 30–24 m, 12–5 m and 2–1 m, formed in relation to sea-level lowstands; whereas marine-influenced sediments at depths of 24–12 m and 5–2 m correspond to sea-level highstands, respectively. Our results highlight two sets of marine influenced sedimentary stratigraphy (T1, T2) dated to ~7 ka and around 130–120 ka, but no obvious MIS 3 transgression recorded in this core. In general, the conclusion is consistent with previous studies in East Asia and beyond, but not with previous work in this region that relied on radiocarbon dating. This suggests that re-dating with luminescence techniques is required for deposits correlated with the MIS 3 transgression in the northern JCP. Our reconstructed terrestrial-marine alternation sedimentary history of the northern JCP also shows a strong linkage with changes in the relative sea-level over the glacial-interglacial cycles. • A ~130 ka sedimentary history of the northern Jiangsu coastal plain is revealed by luminescence dating. • Marine influenced sedimentary stratigraphy only occurred in MIS 5 and MIS 1 in our coring area since the last interglacial. • Further application of luminescence dating to the chronostratigraphy where MIS 3 marine sediments were found is necessary. [ABSTRACT FROM AUTHOR]

Dating of sediments in the tidal-dominated Yangtze River delta remains a challenge because of extremely complicated processes during sediment transport and deposition in such a fluvial-marine transition zone. To better understand the late Quaternary sedimentary history of the Yangtze River delta, we explore the applicability of K-feldspar luminescence dating techniques to deposits through a case study on a 60-m-long borehole core (YZ07) in the delta and then establish a spanning ~50,000-year-long chronological sequence. A series of luminescence pre-tests, including dose recovery tests and determination of residual dose and fading rates, were implemented using the modified single-aliquot-regenerative dose (SAR) protocol for post-infrared (IR) IR stimulated luminescence (IRSL) measured at 150 °C after prior IRSL at 50 °C (pIRIR 150), respectively. Luminescence characteristics of the prior IRSL (IR 50) and pIRIR 150 were then analyzed to check their validity. Two fading-correction models were utilized to correct apparent ages obtained from IR 50 and pIRIR 150 signals. The newly obtained K-feldspar luminescence ages were compared with quartz OSL ages and 14C ages. Our results indicate that most of ages derived from pIRIR 150 signals were overestimated due to incomplete bleaching; in contrast, the fading-corrected ages from IR 50 measured in pIRIR 150 protocol are robust as they are consistent with quartz OSL ages and 14C ages as well as the stratigraphy. Additionally, IR 50 ages are characterized by negligible residual dose, and thus used for defining chronology of the investigated sequence over the past 50 ka. In combination with sedimentological and paleontological analyses of core YZ07, we find that fluvial to tide-influenced fluvial deposits were emplaced during the period 30–50 ka, which were then overlain by post-glacial tidal-river (13–11.5 ka), and Holocene estuarine-shelf, delta system, and tidal flat deposits in the Yangtze River delta. Together with other chronostratigraphy from the selected cores, we confirm the existence of Marine Isotope Stage (MIS) 3 depositional units along the marginal coast of the Yangtze River delta in relation to the interstadial sea-level highstand. Our stratigraphic correlation based on the refined chronology reveals offshore transition of the MIS 3 unit into facies deposited in deeper and offshore marine environments. • Testing the applicability of the K-feldspar pIRIR 150 dating methods for the late Quaternary Yangtze River delta deposits. • K-feldspar corrected IR 50 ages serve as robust age control for the late Quaternary deposits in the Yangtze River delta. • This study reveals that tide-influenced fluvial and fluvial channel environments occurred in the MIS 3 Yangtze River delta [ABSTRACT FROM AUTHOR]