Moondyne Cave Modern Speleothem Stable Isotope Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Moondyne Cave Modern Speleothem Stable Isotope Data LAST UPDATE: 7/2008 (Original receipt by WDC Paleo) CONTRIBUTOR: Pauline Treble, Australian National University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2008-069 WDC PALEO CONTRIBUTION SERIES CITATION: Treble, P.C., et al. 2008. Moondyne Cave Modern Speleothem Stable Isotope Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2008-069. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Treble, P., J. Chappell, M. Gagan, T. Harrison, and K. McKeegan. 2005. In situ measurement of seasonal d18O variations and analysis of isotopic trends in a modern speleothem from southwest Australia. Earth and Planetary Science Letters, 233: 17-32. ABSTRACT: We present a record of seasonal and inter-annual oxygen (d18O) and carbon (d13C) isotope ratios from an 81-year-old stalagmite from Moondyne Cave, southwest Australia. The growth history of stalagmite MND-S1 is known since it grew on a cave boardwalk that was installed in 1911 and removed in 1992. This stalagmite provides an excellent test of speleothem climate proxies because the regional climate is strongly seasonal (wet winter/dry summer) and has experienced a 200 mm (20%) reduction of mean rainfall since the mid-1960s, and a 0.8 degrees C temperature rise since ~1953. Seasonal variations in calcite d18O were measured in situ by high spatial resolution ion microprobe, whilst inter-annual variations of d18O and d13C were measured by conventional gas-source mass spectrometry. Comparison of the speleothem stable isotopes and instrumental temperature records reveals that d18O variations are too large to be driven by temperature alone, and are in the opposite sense. However, daily rainfall d18O measurements show that the mean seasonal range in d18O of rainfall in southwest Australia is large (2 parts per thousand) and inversely correlated with rainfall amount. A rainfall driver for the speleothem d18O is confirmed by the detection of seasonal shifts of 0.7-1.5 parts per thousand in speleothem d18O that track rainfall d18O, smoothed by storage in the overlying limestone. The seasonal range in speleothem d18O is larger than any interannual and decadal variation observed in the record. The prominent annual cycles in speleothem d18O revealed by ion microprobe analysis indicate that subtle changes in the frequency of intense winter rainfall events, or possibly also moisture sources, could produce significant changes in mean speleothem d18O. The ion microprobe results also raise the possibility that the masses of speleothem calcite deposited in winter and summer could vary as a function of the seasonal drip rate and carbonate saturation state of these waters. If this is the case, then small changes in the relative masses of calcite deposited in winter and summer could produce significant shifts in mean d18O and d13C that have a complex relation to climate. This finding should be generally applicable to the interpretation of long-term trends in speleothem geochemical records for shallow cave sites where seasonal variations in geochemical tracers are relatively large, including most of the sub-tropical monsoon belts and mid to high latitudes with distinct rainfall seasons. ADDITIONAL REFERENCE: Fischer, M.J. and P.C. Treble. 2008. Calibrating climate-18O regression models for the interpretation of high-resolution speleothem 18O time series. J. Geophys. Res., doi:10.1029/2007JD009694, in press. GEOGRAPHIC REGION: Southwest Western Australia PERIOD OF RECORD: 1911 - 1992 AD FUNDING SOURCES: Australian Postgraduate Award and RSES, ANU (P.T.) DESCRIPTION: Data were originally published in Treble et al. 2005 EPSL. d18O data are compared with the instrumental record and interpreted as a proxy for rainfall. A recently updated and more accurate interpretation of the dataset are given in Fischer and Treble JGR, in press, doi: 10.1029/2007JD009694). Fischer and Treble demonstrate the effect of changing moisture source on speleothem d18O by examining variations in circulation indices through the study period. Moondyne Cave, Stalagmite MND-S1, southwest Western Australia: 34°16'S, 115°05'E, 100m elev. DATA: Moondyne Cave Stalagmite MND-S1 Stable Isotope Data Age d13C d18O 1912 -9.0158 -3.8359072 1914.6 -9.0003 -3.803568 1918.16 -9.1512 -3.8588224 1921.13 -9.0844 -3.856144 1923.77 -9.0611 -3.80831331 1926.23 -9.3659 -3.79660653 1928.7 -9.769 -3.8320245 1929.94 -9.69 -3.65 1931.18 -9.717 -3.5482839 1933.53 -9.8513 -3.52953321 1934.7 -10.1 -3.47 1935.87 -9.9555 -3.5229 1938.22 -9.8547 -3.5253 1939.32 -9.86 -3.48 1940.42 -9.4067 -3.4814 1942.56 -9.1776 -3.35035995 1943.64 -9.25 -3.32 1944.72 -8.9219 -3.31970406 1945.8 -9.1 -3.36 1946.88 -8.8785 -3.36534066 1949.18 -9.2986 -3.44649444 1950.34 -9.45 -3.39 1951.5 -9.2081 -3.40363572 1953.49 -9.0618 -3.48905553 1955.39 -8.823 -3.6916 1957.29 -8.9393 -3.7933326 1959.76 -8.6723 -3.79184445 1962.37 -8.2904 -3.6929 1964.76 -8.0811 -3.61455618 1965.785 -8.71 -3.69 1966.81 -8.599 -3.72001641 1968.53 -8.4793 -3.7309 1970.2 -8.6921 -3.78112977 1972.48 -8.7376 -3.80652753 1973.665 -8.99 -3.76 1974.85 -8.8417 -3.75731937 1976.87 -8.6264 -3.79065393 1979.33 -8.4975 -3.66822879 1981.8 -8.6006 -3.68152293 1984.13 -8.2066 -3.61683801 1986.47 -7.6535 -3.52685454 1988.99 -7.5185 -3.522336 1990 -7.5612 -3.4926 1991.5 -7.6628 -3.4781