부산대학교 도서관

This thesis develops new, and expands existing, methods of reconstructing paleoclimate from geochemical proxies hosted in secondary carbonate precipitates. This is done by: i) Developing a new multi-proxy approach for using lacustrine cave carbonates (LCCs) to reconstruct past shifts in precipitation-evaporation (P-E) over lake drainage basins, and ii) Investigating the suitability of speleothems as paleo-ENSO archives. Chapters 2 and 3 use modelled and measured values from LCC samples to generate a framework for understanding how Mg/Ca, U/Ca and δ44/42Ca in LCCs can be used as a combined multi-proxy approach to reconstruct past shifts in P-E. This multi-proxy approach is subsequently used to generate a novel reconstruction of P-E over the Bonneville Basin (a terminal basin in the Great Basin region of the southwestern United States), during Heinrich Stadial 1. Results suggest that moisture supply to the Great Basin region was impacted by a southwards shift of the ITCZ and variations in the elevation of North American ice sheets during Heinrich Stadial 1. Chapter 4 investigates the suitability of applying speleothem BA03 as a paleo-ENSO archive. Firstly, the impacts of age model and δ18O uncertainties on speleothem ENSO variability reconstructions are quantified. A total of eight high resolution (> 2 samples per year) δ18O time-series are then used to reconstruct shifts in ENSO variability over the Holocene. This new ENSO variability reconstruction suggests a reduction in ENSO variability during the mid-Holocene (5.68 kyr BP - 3.78 kyr BP), the termination of which coincides with the end of the so called "4.2 Kyr Event". This thesis advances the paleoclimate application of numerous geochemical proxies, expanding the use of precisely dated, high-resolution secondary carbonate archives.