DOI: 10.25921/xv05-8s73
title: NOAA/WDS Paleoclimatology - China 640,000 Year Speleothem Oxygen Isotope Data

description: Oxygen isotope records from Chinese caves characterize changes in both the Asian monsoon and global climate. Here, using our new speleothem data, we extend the Chinese record to cover the full uranium/thorium dating range, that is, the past 640,000 years. The record's length and temporal precision allow us to test the idea that insolation changes caused by the Earth's precession drove the terminations of each of the last seven ice ages as well as the millennia-long intervals of reduced monsoon rainfall associated with each of the terminations. On the basis of our record's timing, the terminations are separated by four or five precession cycles, supporting the idea that the '100,000-year' ice age cycle is an average of discrete numbers of precession cycles. Furthermore, the suborbital component of monsoon rainfall variability exhibits power in both the precession and obliquity bands, and is nearly in anti-phase with summer boreal insolation. These observations indicate that insolation, in part, sets the pace of the occurrence of millennial-scale events, including those associated with terminations and 'unfinished terminations'.
description: New and previously published stalagmite oxygen isotope (d18O) data from 4 Chinese caves, covering the past 640,000 years. Using new oxygen isotope records of five stalagmites (D8, SB-12, SB-14, SB-32, and SB-58) from Dongge and Sanbao Caves, we extend the Chinese speleothem oxygen isotope record to cover the last 640,000 yrs. The composite 640 kyr record is based on previously published data (< 384 kyr BP) and new data from four Sanbao stalagmite records (>= 384 kyr BP) from this study (SB-12, SB-14, SB-32 and SB-58). The new d18O record from Dongge Cave (D8) replaces the previously published records between 217.2 and 225.3 kyr BP, as the age control of stalagmite D8 is superior for this time period. In order to remove the orbital insolation component from the composite d18O record, we used z-standard method to get the detrended d18O data (Delta d18O). We first converted the composite d18O data to z-standard by using the mean and standard deviation of each data set (that is, zero-mean normalization). An average data resolution of 200 years was used to allow point-to-point alignment. The detrended d18O data (Delta d18O) was obtained by subtracting 21 July insolation at 65N from the d18O record after standardization and equal spacing to the 200-year interval. Insolation is normalized to be equal in magnitude to d18O and assigned an opposite algebraic sign: Delta d18O = d18O - (- NHSInorm) = d18O + NHSInorm. Provided Keywords: Speleothem, Asian monsoon, oxygen isotope, Northern Hemisphere Insolation, Ice age terminations. 

The data sources and references for the composite are:
 
 <384 ka BP (From previously published data):
 Wang, Y. J. et al. A high- Resolution Absolute-Dated Late Pleistocene Monsoon Record from Hulu Cave, China. Science 294, 2345-2348 (2001).
 Yuan, D. X. et al. Timing, duration, and transition of the Last Interglacial Asian Monsoon. Science 304, 575-578 (2004).
 Dykoski, C. A. et al. A high resolution, absolute-dated Holocene and deglacial Asian monsoon record from Dongge Cave, China.  Earth Planet. Sci. Lett. 233, 71-86 (2005).
 Kelly, M. J. et al. High resolution characterization of the Asian Monsoon between 146,000 and 99,000 years B.P. from Dongge Cave, China. Paleogeography, Paleoclimatology, Paleoecology 236, 20-38 (2006).
 Wang, Y. J. et al. Millennial- and orbital- scale changes in the East Asian Monsoon over the past 224,000 years. Nature 451, 1090-1093 (2008).
 Cheng, H. et al. Ice Age Terminations. Science 326, 248-252 (2009).

 384 ka to 641.3 ka BP (From this study):
 SB-14 Record: from 384.0 to 425.0 ka BP and from 462.2 to 503.8 ka BP
 SB-12 Record: from 425.0 to 444.0 ka BP
 SB-58 record: from 444.0 to 462.2 ka BP
 SB-32 record: from 504.2 to 641.3 ka BP

 Note 1: D8 record: replaces previous record between 217.2 and 225.3ka BP; Note 2: The original Dongge and Hulu d18O values are reduced by 1.6 per mil in the composite record to match Sanbao record. See Wang, Y. J. et al. Millennial- and orbital- scale changes in the East Asian Monsoon over the past 224,000 years. Nature 451, 1090-1093 (2008).