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Abstract: Tectonic uplift and climate change play a key role in the evolution of sedimentary systems in terrestrial basins. The Qaidam Basin in the northeastern Tibetan Plateau is well suited for studying these processes because of its location and its thick, continuous sequence of Cenozoic sediments. Unfortunately, however, there is a lack of continuous, well‐dated sedimentary records from the region. In the present study, we combined grain‐size analyses of sediment cores and outcrop samples with structural analysis of seismostratigraphic data from the western Qaidam Basin. The results reveal dramatic shifts in the depositional environment at ~11.5–10 Ma, coeval with the topographic development of the area. Together with paleoclimatic analysis and a conceptual model, we conclude that tectonic movements, rather than climatic changes, were the dominant forcing factor. [ABSTRACT FROM AUTHOR]

Understanding the variations in temporal allergenic airborne pollen (AAP) distribution and the mechanisms of pollen release and dispersal during pollen season is fundamental for predicting respiratory allergies, as well as assessing the effects of meteorological conditions on vegetation. In this paper, we described the seasonal variations of in situ AAP for dominant taxa in samples obtained from 11 May 2019 to 31 March 2022, with uninterrupted quasi-monthly sampling time intervals (22–48 days). We also discussed how meteorological factors drive pollen variations in an arid region of Northwest China through correlation analysis and the HYSPLIT model. Results showed: (1) The three most prevalent AAP taxa were Artemisia (65.1% by average), Amaranthaceae (13.5% by average), and Poaceae (6.5% by average), with a high cumulative pollen concentration (CPC) value during July–September period. (2) The duration and total CPC in pollen season were shorter and lower in 2020 than that in 2019 and 2021, which were attributed to the lower precipitation and higher temperature from July to September 2020. In contrast, the wind was the dominant factor influencing each sample's CPC in the non-pollen season. (3) Both the predominant potential source area (PSA) and short transport pathways suggested AAP mainly comes from the local and regional areas. (4) There would be a serious risk of allergy to the three AAP types, especially Artemisia. Our results reveal that precipitation and temperature during July–September have an immediate effect on the characteristics of the AAP pollen season in arid regions. • Artemisia , Amaranthaceae, and Poaceae were the three most prevalent AAP types in the XiangRiDe area. • Precipitation and temperature were the dominant factors affecting the variations of the pollen season proxies. • Pollen potential source areas mainly came from local areas, as well as regional sources. • The potential threat of allergy to the three AAP in XiangRiDe would be more severe than in other northern regions. [ABSTRACT FROM AUTHOR]

Abstract: Thick Cenozoic deposits in the Qaidam Basin provide great potential for understanding the tectonic history, paleoclimatic changes, and evolution of the East Asian Monsoon. This study examines the pollen record from the KC-1 core for the interval covering the later Early to Late Miocene (18–5Ma). Thermophilic taxa percentages are high between 18 and 14Ma and decrease after this time, a pattern which fits well with the Middle Miocene Climatic Optimum (MMCO) between 18 and 14Ma and global climatic cooling after 14Ma. During the same period, xerophytic taxa percentages gradually increase and those of the conifers gradually decrease, suggesting an aridification process in the Qaidam region driven by the gradual strengthening of the East Asian winter monsoon (EAWM) and weakening of the East Asian summer monsoon (EASM). The global climate cooling process appears to have driven the climatic development of the Qaidam Basin region throughout the Miocene, but the uplift of the Tibetan Plateau also contributed. [ABSTRACT FROM AUTHOR]

Abstract Two competing factors, the global cooling and the uplift of Tibetan Plateau, have been proposed to drive the central Asian aridification, but their relative role has seldom been discriminated in paleoclimate and paleoenvironment records. Here, we reconstruct a 14-million-year-long record of paleohydrology and paleoecology in the western Qaidam Basin by applying the compound-specific hydrogen (δ2H) and carbon (δ13C) isotope analyses to terrestrial leaf wax long-chain n -alkanes. The δ2H values are low during the interval of 14.6 to 13.0 Ma. Then the δ2H increases from 13.0 to 12.2 Ma and maintains high values from 12.2 to 3.2 Ma with a peak high value of −156.1‰ at 8.0 Ma. After 3.2 Ma, the δ2H values are low and vary larger than 30‰. The δ13C values decrease from 14.6 to 13.0 Ma and are low from 13.0 to 3.2 Ma except a high value at 3.8 Ma. Then they decrease slightly after 3.2 Ma. Low δ2H values indicate relatively wet climate between 14.6 and 13.0 Ma. The decreasing δ13C values during the same time period support the ecologic shift with the decline of warm component of conifers after the Mid-Miocene Climatic Optimum. High δ2H values since 13.0 Ma are synchronous with the uplift of northern Tibetan Plateau, implying tectonics-driven aridity. Large-amplitude variation in δ2H values since ca. 3.2 Ma seen in East and West Qaidam and lower δ13C values reveal the climatic cyclic responses to the Northern Hemisphere Glaciation. Highlights • Decreasing δ13C since 14.6 Ma reflects the ecologic shift after the MMCO. • High δ2H values since ca. 13.0 Ma indicates aridity in central Asia. • The diachronous response of ecology and climate to MMCO indicates different driving factors. • Low δ2H and δ13C since ca. 3.2 Ma is synchronous with the Northern Hemisphere Glaciation. [ABSTRACT FROM AUTHOR]

Abstract: Drying of the Asian interior has generally been linked to Tibetan Plateau uplift, retreat of the Para-Tethys Sea and global cooling. However, lack of detailed aridification records hinders elucidation of how drying is controlled by these factors and to what extent each factor contributes. In this study, a 600m deep core (SG-3) of lacustrine–playa deposits was obtained from the western Qaidam Basin, NE Tibetan Plateau for pollen analysis. Magnetostratigraphic dating of the core determines its age at ca. 3.1–0.01Ma. The palynologic compositions show that a steppe to desert vegetation predominates the core. Artemisia-dominated steppe representative of relative warm and wet climate before 2.6Ma changed to Chenopodiaceae-dominated steppe desert under drier climate conditions between 2.6Ma and 0.9Ma, interrupted by a short moister interval of Artemisia-dominated steppe at 1.8–1.2Ma. From 0.9Ma to 0.6Ma, Chenopodiaceae–Ephedraceae desert vegetation started to develop, and since 0.6Ma, Ephedraceae-dominated desert prevailed. This vegetation change in the western Qaidam Basin suggests a stepwise long-term aridification of the central Asia inland beginning at ca. 2.6Ma, 1.2Ma, 0.9Ma and 0.6Ma since the late Pliocene, most probably as a response to both long-term global cooling and Tibetan Plateau uplift at those times. [Copyright &y& Elsevier]

Abstract: A sporopollen record recovered from 5.3–1.83Ma sediments was obtained from the lacustrine Yahu section in the central Qaidam Basin of inner Asia. The results provide evidence for vertical zonation of vegetation on the mountains surrounding the basin during the Pliocene and development of forests on the mountains and grasslands around the lake basin. At 3.6Ma, herbaceous plants (especially xerophytic plants such as Artemisia, Chenopodiaceae and Ephedra) increased for a short time within the basin. Xerophytic plants increased continually after 2.6Ma in the basin, which exhibited steppe vegetation, and the climate became drier than before. These vegetation changes in the region of the Yahu section suggest a process of stepwise aridification in Central Asia''s interior since the Pliocene, and it may be related to global cooling and uplift of the Tibetan Plateau. [Copyright &y& Elsevier]

Abstract: The closed inland Qaidam Basin in the NE Tibetan Plateau contains possibly the world''s thickest (∼12,000 m) continuous sequence of Cenozoic fluviolacustrine sedimentary rocks. This sequence contains considerable information on the history of Tibetan uplift and associated climatic change. However, work within Qaidam Basin has been held back by a paucity of precise time constraints on this sequence. Here we report on a detailed paleomagnetic study of the well exposed 4570 m Huaitoutala section along the Keluke anticline in the northeastern Qaidam Basin, where three distinct faunas were recovered and identified from the middle Miocene through Pliocene. Constrained by these faunal ages, the observed thirty-three pairs of normal and reversed polarity zones can be readily correlated with chrons 2n-5Br of the GPTS. This study assigns the age of the section to the interval between ca. 15.7 Ma to 1.8 Ma. In addition, the widely used stratigraphic units the Xia Youshashan, Shang Youshashan, the Shizigou and Qigequan Formations were formed at >15.3 Ma, 15.3–8.1 Ma, 8.1–2.5 Ma and <2.5 Ma, respectively. We obtained a very high average sedimentation rate of ∼33 cm/ka over the entire interval 15.7 to 1.8 Ma. Furthermore, the average sedimentation rate is punctuated by three intervals of persistent rapid increases starting at about ∼14.7 Ma, 8.1 Ma and 3.6 Ma. These intervals are interpreted as times of rapid uplift and fast exhumation of the NE Tibetan Plateau. [Copyright &y& Elsevier]