Paleomagnetic Secular Variation and Relative Paleointensity During the Holocene in South China—Huguangyan Maar Lake Revisited

Abstract

The scarcity of reliable paleomagnetic secular variation (PSV) records from East Asia especially from low‐latitude regions impedes better understanding of global PSV mechanisms. Here we report on a radiocarbon‐dated Holocene PSV record from a composite ~6.7‐m‐long core collected from the high‐sedimentation‐rate Huguangyan Maar Lake (HML) in subtropical‐tropical South China. Rock magnetic results demonstrate that the natural remanent magnetization resides in single‐domain magnetite. Alternating field demagnetization experiments at 1‐cm spacing on u‐channel samples reveal six distinct inclination highs at ~7,500 BCE, ~5,100 BCE, ~4,600 BCE, ~3,600–3,400 BCE, ~1,600–1,200 BCE, and 600–800 CE; three inclination lows at ~4,800 BCE, ~600–300 BCE, and ~1,000–1,300 CE; and three eastward declination trends at ~3,600–3,200 BCE, ~2,600–2,400 BCE, and 400 BCE to 200 CE. The similarity between the HML PSV record and other independently dated records from East Asia and geomagnetic field models corroborates the robustness of our age model and Holocene PSV record. Strikingly, centennial‐ to millennial‐scale PSV features of the HML are comparable, within age uncertainties, with other Holocene records from Europe, North America, and Canada, suggesting that such directional patterns are likely to be hemispheric in scale. Although relative paleointensity data of HML are affected by environmental factors (e.g., organic matter diagenesis), the record still provides a regionally important new PSV reference curve whose conspicuous features may serve as stratigraphic markers for East Asian paleorecords.

Paleosecular Variations During the Last Glacial Period From Tengchong Qinghai Lake, Yunnan Province, China

“…(a) Yumco Lake in Tibet (Henkel et al., 2016); (b) Tengchong QH Lake; (c) CALS10k.1b and HFM.OL1.A1 models (Constable et al., 2016; Korte et al., 2011); d and (e) Huguangyan Lake from Sheng et al. (2019) and Yang et al. (2012), respectively; (f) Shuangchiling Lake (Yang, Heller, Yang, & Su, 2009); and (g) Eastern China stacked curve (Y. Zheng et al., 2014).…”

Multidecadal‐ to Centennial‐Scale 10Be Variations in Holocene Sediments of Huguangyan Maar Lake, South China

“…For the uppermost portion of the core, we used the 137 Cs age model of Wang et al (). For depths below this, a Bayesian age model based on 9 AMS 14 C dates has been constructed (Sheng et al, ), using the BACON 2.2 program (Blaauw & Christen, ). The newly obtained paleomagnetic secular variation curves (inclination and declination) by Sheng et al () is fully compatible with paleomagnetic secular variation reference curves, reinforcing the robustness of age model.…”

“…For depths below this, a Bayesian age model based on 9 AMS 14 C dates has been constructed (Sheng et al, ), using the BACON 2.2 program (Blaauw & Christen, ). The newly obtained paleomagnetic secular variation curves (inclination and declination) by Sheng et al () is fully compatible with paleomagnetic secular variation reference curves, reinforcing the robustness of age model. A total of 271 BeO samples were obtained at 2‐ to 5‐cm intervals and treated as described in Text S2 in the supporting information.…”

A combined geophysical and lithological study on eruptive history and Quaternary lacustrine stratigraphy of a maar in Leizhou Peninsula, China

“…4). Organic matter diagenesis may induce the dissolution of ironbearing minerals via iron reduction and consequently, lower κ values of sediments (Sheng et al 2019). Few diatoms in this stage possibly indicate a high humic acid content.…”