This thesis develops and applies new techniques for reconstructing past environments from the speleothem archive. Chapter 3 introduces Ca isotopes as a novel palaeo-aridity proxy. Recent dripwater, farmed calcite and bedrock data show that, in the modern environment, 36% of initial dripwater Ca is removed by prior calcite precipitation at the HS4 dripsite (Heshang Cave, Central China). A speleothem record spanning the 8.2kyr event suggests this value increased to 60% during the event, in response to a decrease in effective rainfall of approximately a third. Modern Ca isotope systematics, and the cycling of other Group II metals, are studied further in Chapter 4. Data from Heshang Cave monitoring samples explore the temporal and spatial controls on these proxy systems. Results highlight the importance of secondary calcite as a potential source of dripwater metals, as well as the significant contribution of particulate calcite to bulk dripwater chemistry. At the HS4 dripsite, over a third of bulk dripwater Ca is present as particulate calcite. This influences bulk dripwater Ca concentrations and isotopes, as well as potentially impacting speleothem growth and chemistry. Chapters 5 introduces CaveCalc, a new numerical model for dripwater and speleothem chemistry and isotopes based on PHREEQC. Key strengths of CaveCalc include its ability to model multiple proxy systems in a single framework, the ability to quantify the extent of open-system dissolution, and the extensible nature of its design. Chapter 6 applies CaveCalc to disentangling the controls on dripwater and speleothem δ¹³C values. Model results are compared with speleothem data. At Heshang Cave, anomalously high δ¹³C is quantitatively explained as the result of CO₂ degassing and prior calcite precipitation, an interpretation made possible by the availability of coupled δ¹³C, a¹⁴C and Ca isotope data. This approach provides a powerful tool to help researchers better interpret dripwater and speleothem δ¹³C data.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1983. / Vita. Includes bibliographical references (p. 268-279).

Thesis (Ph.D.) -- University of Adelaide, Dept. of Geology, 2000. / Includes bibliographical references (10 leaves).

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1993. / "June 1993." At head of title: Woods Hole Oceanographic Institution, Massachusetts Institute of Technology, Joint Program in Oceanography/Applied Ocean Science and Engineering. "Doctoral dissertation." Includes bibliographical references.