Spatiotemporal evolution of aeolian sedimentary landscapes on the southern Tibetan Plateau during the late Quaternary: A review and recent advances

Abstract

The aeolian deposits on the southern Tibetan Plateau (TP) are one of the most important environmental archives preserved at the highest altitudes worldwide, containing extensive information about both the current and past landscapes and environments of Earth's Third Pole. Over the past three decades, these deposits have attracted considerable attention in Quaternary paleoclimate research. Nevertheless, our understanding of these high-altitude aeolian deposits is significantly less than that for similar deposits in the low-altitude regions of the Eurasian continent. To better comprehend this important archive, it is essential to integrate knowledge from various perspectives. However, there is a lack of consensus regarding their formation, distribution, chronology, provenance, and paleoclimatic history across different timescales. Here, based on our recent field investigations and new data, along with previously published data, we present the results of a systematic analysis of aeolian deposits on the southern TP. Our principal results and findings are: (1) We present up-to-date maps of the aeolian deposits, consisting of an overview map of the overall spatial distribution, and six high-resolution regional maps highlighting details of the depositional areas. Loess and sand dunes have accumulated within the six subdomains, following the global pattern of dust accumulation along rivers in arid and semi-arid regions. (2) Based on paleomagnetic and ESR dating, the oldest aeolian sediments were formed during the middle Pleistocene. The probability density of 220 OSL and AMS ¹⁴C ages reveals that 98.7 % of the young sediments accumulated since the last interglacial, with the majority (66.4 %) forming during the Holocene. A comparison of age clusters with records of ice volume, temperature, precipitation, vegetation, and paleolakes revises previous hypotheses regarding the factors influencing dust deposition, emphasizing the dominant control of climate change. (3) The aeolian sediments are of local origin and their sources remained relatively stable over time. Quantitative analysis of 48 samples using geochemical fingerprinting showed that the aeolian sediments are a mixture of various clastic materials derived from upstream areas, with the predominant contribution from sand dunes (58.7 %). (4) We examined the climatic evolution of this region and its driving mechanisms during the middle to late Pleistocene and the Holocene. This analysis suggests that changes in cold and warm season insolation were the primary external drivers of moisture and dust activity on both orbital and sub-orbital scales. The winter mid-latitude Westerlies and the Indian summer monsoon, which are influenced by these seasonal insolation variations, regulated the moisture evolution, while the near-surface winds, primarily driven by cold season insolation and influenced by ice volume and oscillations in North Atlantic climate, played a significant role in modulating dust activity. Accordingly, we present a comprehensive conceptual model to illustrate the theoretical framework of aeolian sedimentary landscapes and their impacts and responses to regional and global climate changes. Overall, this review contributes to an improved understanding of the late Quaternary evolution of dust deposition and the environment on the southern TP.