GRGC: Developing an Absolutely-Dated Holocene Tree-Ring Chronology from Subfossil Huon Pine in Tasmania for Paleoclimatic and Isotopic Studies

9310093 Cook This 3-year proposal is for funding to continue the development of a continuous, absolutely-dated Holocene tree-ring chronology from live Huon pine trees and sub-fossil logs collected in western Tasmania, Australia. Progress to date includes the development of two absolutely-dated Huon pine annual tree-ring chronologies extending back over 2,000 years from the present time, the reconstruction of warm-season Tasmanian temperatures since 300 BC from one of these series, the development of two floating, sub- fossil tree-ring chronologies in the 4-6,000 years BP range, and the excavation of 105 new sub-fossil Huon pine logs from the Stanley River flood plain. Radiocarbon dates of six of these new logs indicates ages of 4-7,000 yrs BP, plus two other logs with dates in the 30,000 yrs BP range. The latter two, each containing several hundred rings, are among the oldest, well-preserved, sub- fossil logs yet discovered anywhere and are proof that recoverable Huon pine wood from the last glacial epoch is present in Tasmania. Consequently, the development of a continuous tree-ring chronology extending back into the late-Pleistocene is a very real possibility. The bulk wood from this collection and the proposed new collections will eventually be used for isotopic analyses and the likely extension of the high-precision radiocarbon calibration curve back into the last glacial epoch. Over the next three years, we will process the sub-fossil wood now in hand, extend the existing tree-ring chronology back in time, and continue to collect more sub-fossil Huon pine wood from area in western Tasmania. In Addition, we will develop new and extended climatic reconstructions for Tasmania, including the probable extension of the warm-season temperature reconstruction back to 2,000 BC.