1. Lead Components of Bulk Sediments from Dahu Swamp in Nanling Mountains (South China): Implications for the Climatic and Environmental Changes Since the Last Deglaciation.
- Author
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Wei Zhong, Quan, Mingying, Wei, Zhiqiang, Shang, Shengtan, Ye, Susu, Li, Tianhang, and Yu, Jian
- Subjects
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CLIMATE change , *WEATHER & climate change , *LEAD isotopes , *GLACIAL melting , *CHEMICAL weathering , *HOLOCENE Epoch - Abstract
We show, from a 16.6 ka record of lead isotopes from a core sediments in Dahu Swamp in eastern Nanling Mountains, that the chemical weathering responds to changes in climatic conditions. Pb isotopic signals reveal that the local weathered granitoid was the dominant source of Pb deposition. However, two isotopic excursions appeared from 15.5–15.2 and 5.2–4.8 ka BP, which coincide with the dry/cold H1 event and the mid- and late-Holocene respectively, likely suggesting an additional contribution of aeolian dust from North China. Even more, more radiogenic Pb signal of E2 exhibits a mixed contribution of enhanced anthropogenic mining. We expect strong enough EAWM would dominate these two intervals. Supported by multi-proxy records, we conclude that variations Pb isotopic signals (e.g., 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios) are closely related to climate-induced chemical weathering. Synchronous variations of 208Pb/204Pb, 206Pb/204Pb and 207Pb/204Pb ratios in the core display a congruent Pb isotope signals released from both U- and Th-rich accessory minerals. During intensive chemical weathering under wetter/warmer conditions (e.g., the Bølling and Allerød events, and the Holocene Optimum period), more preferential release of radiogenic 206Pb, 207Pb and 208Pb can be absorbed by fine detritus and then eroded to the lake thus resulting in increased 208Pb/204Pb, 206Pb/204Pb and 207Pb/204 ratios in sediments, and vice versa if a drier/colder climate dominates (e.g., the H1, the Older and Younger Dryas events, and the mid- & late-Holocene). The inferred changes in chemical weathering from Dahu sediments have varied in tandem with multi-regional monsoonal proxies in China, and exhibited a sensitive response of chemical weathering to global climate change. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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