Speleothem biomarker evidence for a negative terrestrial feedback on climate during Holocene warm periods

Abstract

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Possible expression of the 4.2 kyr event in Madagascar and the south-east African monsoon

“…Anjohikely has more restricted chambers and a greater areal coverage of precipitated calcite, especially on the walls and floor. Therefore, while additional evidence from ANJ94-5 suggests that isotopic variability may still be climatic in origin (Wang et al, 2019a), the absolute  18 O values are likely not comparable with AK1, sourced from a more restricted chamber in a 'wetter' cave. Both stalagmites return to higher  18 O (drier conditions) at 2.4kyr BP.…”

Sources, Distribution and Paleoenvironmental Application of Fatty Acids in Speleothem Deposits From Krem Mawmluh, Northeast India

“…The distribution and chain length of fatty acids can trace organic matter sources from a wide range such as bacteria, algae, and terrestrial higher plants in lakes and other aquatic environments (Ouyang et al, 2015;Liu and Liu 2017). An algal origin is less likely in speleothems, and the two main end-members for LMW fatty acids are microbes and higher plants (Wang et al, 2019). Due to lack of information, we could not differentiate bacterial vs. fungal sources of LMW fatty acids in the speleothems.…”

“…The distribution of fatty acids was used to 1) differentiate the source inputs for organic matter derived from overlying vegetation, algae, as well as microbes including bacteria and fungi within the soil or cave (Ruess et al, 2002;Ouyang et al, 2015;Wang et al, 2019), and 2) reconstruct paleoenvironmental conditions such as temperature and precipitation (Table 1).…”

A Review of Speleothems as Archives for Paleofire Proxies, With Australian Case Studies

“…However, a correlation between Sr/Ca and Mg/Ca increases the confidence that variations are hydrological. Beyond paleoenvironmental applications, seasonal changes in Sr/Ca may be used to develop precise annual speleothem chronologies (e.g., C. Wang et al., 2019, see also Section 5.2.3). It has been demonstrated that trace metals are transported in infiltrating karst waters as both particulates and colloids with organic matter, with dripwater metal ratios closely associated with natural organic matter (Hartland et al., 2012).…”