Xuefeng Wang

Marine Isotope Stage (MIS) 5e, the last interglacial maximum, featured global temperatures ∼2°C higher than present. However, the timing and structure of MIS 5e termination remain poorly constrained with respect to the East Asian Summer Monsoon (EASM). Here, we present two coeval stalagmite δ ¹⁸ O records from North China spanning 125.0–117.7 ka BP, with inter‐decadal resolution and robust ²³⁰ Th dating (±0.3 kyr). The EASM weakening that marks the MIS 5e/5d transition occurred between 121.4 ± 0.4 and 119.8 ± 0.3 ka BP, a period lacking clear evidence for a pronounced Atlantic Meridional Overturning Circulation (AMOC) slowdown, which challenges the view that abrupt AMOC weakening was the primary driver. Instead, this EASM weakening was likely driven by low‐latitude processes, linked to the reduced Indo‐Pacific Warm Pool upper ocean heat content and southward shift of Intertropical Convergence Zone resulting from the diminished meridional summer insolation gradient. In contrast, a pronounced EASM weakening between 125.0 ± 0.3 and 123.1 ± 0.3 ka BP broadly coincides with a North Atlantic cooling event within MIS 5e associated with freshwater‐induced AMOC slowdown, underscoring climatic instability during the warmer interglacial. Together, these findings demonstrate that fundamentally different mechanisms governed EASM weakening during MIS 5e and its termination.

The impact of rapid climate change on civilizations is of global concern. The Western Zhou (1045–771 BC) was ancient China’s third dynasty and one of the most powerful empires of its time. After a 274-year reign, the dynasty collapsed, accompanied by significant population migration. Various factors have been proposed to explain its fall, while the role of climate change has been largely ignored. Here we present well-dated, high-resolution stalagmite records from Northeast and Southeast China, along with other paleoclimatic and archaeological evidence, to demonstrate the critical role of the 2.8 ka climatic event in the dynasty’s collapse and subsequent migration. Our results indicate a “north dry–south wet” dipolar pattern in the Chinese monsoon region during this event. The drought and cold severely affected the Western Zhou core areas and exacerbated invasions by northern nomads, contributing to its collapse. The resulting environmental stresses and conflicts likely triggered substantial southward migration.

The elemental compositions of deep‐sea corals are invaluable proxies in high‐resolution reconstructions of deep‐sea paleo‐oceanographic conditions, but the incorporation of minor and trace elements into their skeletons and associated biomineralization are poorly understood. In this study, multielement (Cd, P, Ba, K, S, Co, Mn, Fe, Sr, Na, and Mg) and fluorescence imaging of skeletal cross‐sections of a subapical branch and middle‐basal trunk of a deep‐sea bamboo coral, Jasonisis sp. (collected from the seafloor in front of the Mariana arc (11.95355°N, 141.47446°E) at a depth of 1,385.9 m in October 2019) were undertaken using femtosecond laser ablation‐inductively coupled plasma time‐of‐flight mass spectrometry and laser scanning confocal microscopy, respectively. The spatial associations of minor and trace elements and their organic compositions, and associated growth patterns (cyclic rings) of early‐ (the subapical branch and the near‐core region of the middle and basal trunk) and late‐stage (the middle‐basal trunk excluding near‐core regions) coral skeletons were determined simultaneously. The consistent distribution patterns of most elements and the presence of distinct rings correspond to growth patterns associated with nutrient‐like elements such as Cd, P, and Ba and organic components within the late skeleton. This likely suggest a significant role of nutrients in the biomineralization process during the late stage. The distinct elemental patterns, exhibiting positive correlation among specific elements (e.g., P, S, Mn, Co, and Cd) and negative correlations with others (e.g., Na and Mg), along with the lower organic content observed in the early skeleton, suggest a unique mineralization mechanism during the initial growth stage, with kinetic processes playing a dominant role. Therefore, combined multielement and organic composition mapping of different parts of coral skeletons provides comprehensive insight into coral growth and the incorporation of trace elements.

Gypsum is a common evaporate mineral in a wide variety of geological settings, especially in arid and semi-arid areas. It often precipitated from the natural brine systems with trace amounts of U and almost no Th, rendering it a potentially valuable U-Th geochronometer. However, U-Th dating of gypsum is often challenging, such as how to quickly and completely digest gypsum into solution, and avoid the re-crystallization of gypsum particles during the digestion and chromatography process. Here we present a rapid and practical method for high-precision U-Th dating of gypsum using the (NH4)2CO3 exchange reaction and double-spike method by MC-ICPMS. Our developed protocol addresses these conventional challenges by using the chemical reaction between calcium sulfate and carbonate, resulting in the (NH4)2SO4 solution and CaCO3 precipitate. Then the CaCO3 could be easily digested by diluted acid. With the solid-liquid separation, Ca2+ and SO42- ions are also effectively separated, minimizing the recrystallization of gypsum. The (NH4)2CO3 median, the gypsum/carbonate molar ratio of 1: 4, and the exchange reaction duration of 1.5 ~ 2 hours are suggested in this protocol. Since there is no gypsum U-Th dating reference materials to validate the accuracy of different approaches and ensure methods are repeatable across laboratories. We also prepared and characterized two natural gypsum U-Th dating reference materials (PXCG-1, PXCG-2) from PiXiao Cave, southwest China. Data from three different laboratories exhibit good agreement with both 238U content, δ234U, 230Th/238U activity ratio, and the 230Th ages. The 230Th ages of PXCG-1, PXCG-2 RMs proposed are 66.97 ± 0.31 ka, 260.82 ± 3.39 ka, respectively.

Gypsum is a widespread mineral in various sedimentary deposits. It precipitates from natural aqueous systems with trace amounts of U but almost no Th, rendering it a potentially valuable U–Th geochronometer. However, no gypsum RM for U–Th dating has been available. In this work, two natural gypsum reference materials (PXCG-1, PXCG-2) from the PiXiao cave, southwest China were prepared and characterized for U–Th dating. U–Th contents and isotope ratios were measured on a multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) using the isotope dilution technique. Data from three different laboratories show good agreement in ²³⁸U content, δ²³⁴U (²³⁴U/²³⁸U relative to secular equilibrium value), ²³⁰Th/²³⁸U activity ratio, and ²³⁰Th ages (corrected) (corrected by assuming the initial ²³⁰Th/²³²Th ratio of the average crust value). The recommended values with the uncertainties (2σ) of these two gypsum RMs, ²³⁸U content = 1844 ± 39 ng g⁻¹, δ²³⁴U = 229.3 ± 3.9‰, ²³⁰Th/²³⁸U_activity = 0.5741 ± 0.0036, ²³⁰Th ages (corrected) = 66.97 ± 0.31 ka BP for PXCG-1, and ²³⁸U content = 1636 ± 50 ng g⁻¹, δ²³⁴U = 61.0 ± 2.4‰, ²³⁰Th/²³⁸U_activity = 0.9797 ± 0.0034, ²³⁰Th ages (corrected) = 260.82 ± 3.39 ka BP for PXCG-2, respectively. Information values of ²³²Th content, ²³⁰Th/²³²Th atomic ratio, ²³⁰Th age (uncorrected), and δ²³⁴U_initial are also provided. PXCG-1 and PXCG-2 are the first reported gypsum age RMs for U–Th dating, making them a useful complement to the widely distributed carbonate age reference materials for U–Th disequilibrium dating in Pleistocene–Holocene deposits.

This study presents a rapid and practical method for high-precision U–Th dating of gypsum using the (NH₄)₂CO₃ exchange reaction and double-spike method by MC-ICP-MS.

Uranium isotope ratios are reported for twenty‐nine geological reference materials (RMs) including igneous, metamorphic and sedimentary rocks, as well as sediments. Measurements were conducted on a multi‐collector inductively coupled plasma‐mass spectrometer (MC‐ICP‐MS) using the ²³³U‐²³⁶U double spike technique. These RMs possess a wide range of matrices with U mass fractions ranging from 0.11 μg g^‐1 to 18.7 μg g^‐1. The δ^234/238U values (relative to the n(²³⁴U)/n(²³⁸U) ratio at secular equilibrium) show minor fluctuations around the secular equilibrium value except for two Pleistocene speleothem RMs. The δ^238/235U values (relative to the value for NBL CRM 112a (NBS SRM 960)) of igneous rocks and metamorphic rocks are within the range of the continental crust value (‐0.29 ± 0.03‰, 95% CI). The δ^238/235U value for sedimentary rock and sediment RMs spans a wide range of 0.98‰, suggesting significant ²³⁸U/²³⁵U isotopic fractionation in low temperature environments. The range of δ^238/235U RMs reported in this study (‐0.63‰ to 0.35‰) exceeds that of previous RMs (‐0.61‰ to 0.17‰), allowing inter‐laboratory calibration of wider ranges of geological and environmental samples.

Intense debate persists about the timing and magnitude of the wet phases in the East Asia deserts since the late Pleistocene. Here we show reconstructions of the paleohydrology of the East Gobi Desert since the last interglacial using satellite images and digital elevation models (DEM) combined with detailed section analyses. Paleolakes with a total area of 15,500 km²during Marine Isotope Stage 5 (MIS 5) were identified. This expanded lake system was likely coupled to an 800–1000 km northward expansion of the humid region in East China, associated with much warmer winters. Humid climate across the Gobi Desert during MIS 5 likely resulted in a dustier MIS 4 over East Asia and the North Pacific. A second wet period characterized by an expanded, albeit smaller, lake area is dated to the mid-Holocene. Our results suggest that the East Asian Summer Monsoon (EASM) might have been much weaker during MIS 3.

Three natural geological glasses (andesitic glass OJY‐1, and rhyolitic obsidians OH‐1 and OA‐1) of specimen sizes 50–150 g were characterised as reference materials for in situ microanalysis of major and trace elements, and Pb isotope ratios. Utilised techniques include isotope‐dilution analyses by TIMS and MC‐ICP‐MS, bulk analyses by XRF, ICP‐OES, ICP‐MS, and microanalysis (10–120 μm spot size) by electron probe microanalyser, LA‐ICP‐MS and LA‐MC‐ICP‐MS. Microanalyses (10–120 μm) indicate that all three glasses are homogeneous with respect to fifty‐four out of fifty‐eight determined elements and Pb isotope ratios, except for Ni in OJY‐1, and Cu, Zr and Ce in OH‐1. The determination of reference values as well as their uncertainties at the 95% confidence level closely followed International Organization for Standardization (ISO) guidelines and the certification protocol of the International Association of Geoanalysts (IAG). These three glasses are fully natural without any subsequent heat treatment, and they represent useful additions to the widely distributed MPI‐DING, USGS and CGSG reference glasses for microanalytical techniques such as electron probe microanalysis, μ‐XRF, LA‐ICP‐MS and SIMS.