Tzabnah Cave, Mexico 1500 Year Speleothem Oxygen Isotope Data Medina-Elizalde, M.; Burns, S.J.; Lea, D.W.; Asmerom, Y.; von Gunten, L.; Polyak, V.J.; Vuille, M.; Karmalkar, A. Medina-Elizalde, M. Burns, S.J. Lea, D.W. Asmerom, Y. von Gunten, L. Polyak, V.J. Vuille, M. Karmalkar, A. Monsoon drought earth science/paleoclimate/speleothems (depth,null,null,centimeter,null,speleothems,null,null,N,null) earth science/paleoclimate/speleothems (delta 18O,calcium carbonate,null,per mil VPDB,null,speleothems,raw,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/speleothems (age,null,null,year Common Era,null,speleothems,null,null,N,null) earth science/paleoclimate/speleothems (Tzabnah Cave>LATITUDE 20.75>LONGITUDE -89.466667) The decline of the Classic Maya civilization was complex and geographically variable, and occurred over a ~150-year interval, known as the Terminal Classic Period (TCP, C.E. 800-950). Paleoclimate studies based on lake sediments from the Yucatán Peninsula lowlands suggested that drought prevailed during the TCP and was likely an important factor in the disintegration of the Classic Maya civilization. The lacustrine evidence for decades of severe drought in the Yucatán Peninsula, however, does not readily explain the long 150-year socio-political decline of the Classic Maya civilization. Here we present a new, absolute-dated, high resolution stalagmite d18O record from the northwest Yucatán Peninsula that provides a much more detailed picture of climate variability during the last 1500 years. Direct calibration between stalagmite d18O and rainfall amount offers the first quantitative estimation of rainfall variability during the Terminal Classic Period. Our results show that eight severe droughts, lasting from 3 to 18 years, occurred during major depopulation events of Classic Maya city-states. During these droughts, rainfall was reduced by 52% to 36%. The number and short duration of the dry intervals help explain why the TCP collapse of the Mayan civilization occurred over 150 years. STUDY NOTES: Absolutely-dated, high-resolution stalagmite delta18O record from the northwest Yucatán Peninsula that provides a detailed picture of climate variability during the last 1500 years. In 2004 we collected a 45 cm stalagmite specimen, named Chaac after the Maya god of rain, from cave "Tzabnah" in the village of Tecoh. The speleothem time scale is based on 12 absolute U/Th dates. We applied a polynomial and piecewise linear model and found a maximum age difference between these models of 31 years during the Medieval Climate Anomaly time interval. To test the age model in the critical interval defining the TCP we counted laminations and compared the results to the U/Th age model. The average number of laminations in the time interval between CE 918 and 820, which corresponds to 98 Th-years, is 85±10. This test provides an independent confirmation of the U/Th age model. The U/Th date of C.E. 942 corresponding to the onset of the Medieval Climate Anomaly in Chaac is comparable to the age indicated by the well-dated (Th-dating errors <=5 years) subtropical China stalagmite d18O record for this same event (Zhang et al., 2008). This observation and the laminae counting suggest that the error in the absolute chronology in Chaac is no larger than ±10 years during the Terminal Classic Period. Tzabnah Cave, Tecoh, Yucatán, Mexico: 20°43.83'N, 89°28.47'W, 20 m above sea level. ADDITIONAL REFERENCE: Zhang, P., et al., 2008. A test of climate, sun, and culture relationships from an 1810-year Chinese cave record. Science, Vol. 322, pp. 940-942. NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Medina-Elizalde, M. Investigator : Burns, S.J. Investigator : Lea, D.W. Investigator : Asmerom, Y. Investigator : von Gunten, L. Investigator : Polyak, V.J. Investigator : Vuille, M. Investigator : Karmalkar, A. 2010-09-15 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/9791 https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/mexico/tzabnah2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/mexico/tzabnah2010.xls https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/mexico/tzabnah2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/mexico/tzabnah2010.xls English https://www.ncdc.noaa.gov/paleo/study/9791 https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/mexico/tzabnah2010.txt https://www1.ncdc.noaa.gov/pub/data/paleo/speleothem/northamerica/mexico/tzabnah2010.xls Medina-Elizalde, M., S.J. Burns, D.W. Lea, Y. Asmerom, L. von Gunten, V. Polyak, M. Vuille, and A. Karmalkar. 2010. High resolution stalagmite climate record from the Yucatán Peninsula spanning the Maya terminal classic period. Earth Planet. Sci. Lett. doi:10.1016/j.epsl.2010.08.016 START YEAR: 487 AD * END YEAR: 2004 AD -89.466667 20.75 -89.466667 20.75