This project seeks to generate a Uranium/Thorium (U/Th) dated record of rainfall in the southern tropical Pacific at sub-century (~50 year/sample) resolution for most of the glacial and Holocene periods using stalagmites from the island of Niue and from Tonga. The speleothem from Niue dates to 83,000 years before the present.
Specifically, the researchers will: 1) analyze the Niue specimen, as well as a Holocene-age stalagmite from Tonga, for Oxygen-18, Carbon-13, Magnesium/Calcium ratios, Strontium/Calcium ratios, and Barium/Calcium ratios; 2) generate a precise absolute-dated U/Th age model for the specimens; and 3) undertake drip-water sampling to validate paleoclimate interpretations.
The goal of the project is to examine the following hypotheses: a) at times of increased Thermohaline Circulation (THC), a northward shift of the Pacific Inter-tropical Convergence Zone (ITCZ) dominated over a westward shift in the Walker Cell resulting in decreased rainfall at Niue; and b) rainfall records at Niue will show rapid shifts in phase with Greenland ice-core records, but will also show additional changes characteristic of Antarctic temperature records.
The broader impacts include the potential for a high-quality paleoclimate record from an important and under-studied region. In addition to the scientific importance and support of a graduate student, the researcher will conduct outreach through a NSF-sponsored program through which high-school students and teachers from New Jersey participate in workshops on marine and climate science.
