Palaeoenvironmental changes revealed through multielemental proxies in speleothems – Insights and perspectives from Cave KNI-51 in Kimberly, Australia

Abstract

Climate change manifests as a complex synergy of biogeochemical and physical variations taking place within all earth compartments at different spatial and temporal scales. Paleoclimatic archives spread around the globe capture some of those variations and preserve their signal in the form of specifically representative biotic and physicochemical parameters (proxies). Karsts deposits known as speleothems are important geological and geochemical climate archives, mostly studied for changes in their stable-isotope composition (δ18O and δ13C) to reconstruct past variations in vegetation, temperature or rainfall regimes. Trace elements have been also reported as potential proxies of annual and multi-annual climatic variations in speleothems, and have been shown as particularly effective in recording extreme phenomenon such as droughts and floods. Still, the intricacy of elemental fractionation processes during transport, deposition, crystallization and the complex and site-specific forcing of environmental settings make the interpretation of trace elements pattern in speleothems extremely challenging. The goal of the thesis is: i) to provide a comprehensive and critical review of elemental levels and ratios as paleoclimate proxies in speleothems; ii) investigating the applicative potential of elemental proxies for paleclimate reconstruction through the analysis of a stalagmite recently collected at Cave KNI-51 located in the Ningbing Range of the eastern Kimberley region of Western Australia; iii) to provide a critical perspective for future in-depth studies on the same cave.