Timing, Duration, and Transitions of the Last Interglacial Asian Monsoon

Abstract

Thorium-230 ages and oxygen isotope ratios of stalagmites from Dongge Cave, China, characterize the Asian Monsoon and low-latitude precipitation over the past 160,000 years. Numerous abrupt changes in 18O/16O values result from changes in tropical and subtropical precipitation driven by insolation and millennial-scale circulation shifts. The Last Interglacial Monsoon lasted 9.7 +/- 1.1 thousand years, beginning with an abrupt (less than 200 years) drop in 18O/16O values 129.3 +/- 0.9 thousand years ago and ending with an abrupt (less than 300 years) rise in 18O/16O values 119.6 +/- 0.6 thousand years ago. The start coincides with insolation rise and measures of full interglacial conditions, indicating that insolation triggered the final rise to full interglacial conditions.

High-precision 238U–234U–230Th disequilibrium dating of the recent past: a review

“…Although speleothems have proven a valuable source of information on past climates, it is only in the last few years that the UTh dating of last millennial speleothems for climatic reconstruction has been undertaken (Fleitmann et al, 2004;Yuan et al, 2004;He et al, 2005;Wang et al, 2005;Asmerom et al, 2007;Sinha et al, 2007;Hu et al, 2008;Lorrey et al, 2008). This is largely because of the low U content and high Th/U ratios of speleothems, particularly by comparison with pristine corals.…”

“…TIMS and single-collector HR-ICPMS have been commonly used for dating young carbonates (Edwards et al, 1988;Denniston et al, 2000;Cobb et al, 2003a,b;Fleitmann et al, 2004;Yuan et al, 2004;He et al, 2005;Kirch and Sharp, 2005;Wang et al, 2005;Weisler et al, 2006;Yu et al, 2006a,b;Lorrey et al, 2008;Shen et al, 2008) while MC-ICPMS has only occasionally been used to date young corals (Fietzke et al, 2005;Burgess et al, 2006;Hu et al, 2008;McCulloch and Mortimer, 2008). This is largely due to the fact that the MC-ICPMS technique became available only recently and that the protocols for dating extremely young carbonates are still being developed.…”

“…Many studies have demonstrated that much of the uncertainty associated with age determinations arises from the correction for non-radiogenic or initial 230 Th (Cobb et al, 2003b;Yuan et al, 2004;Kirch and Sharp, 2005;Wang et al, 2005;Yu et al, 2006a,b;Lorrey et al, 2008;McCulloch and Mortimer, 2008;Shen et al, 2008 The following simplified equation may be used to assess the age correction (the contribution of non-radiogenic 230 Th to the measured 230 Th age calculated from Eq. (1)) and its uncertainty for a young (<1000 years old) sample:…”

“…Since that time, the method has been successfully applied to dating a variety of young carbonate deposits. The results have been employed in high-resolution climatic reconstruction (Denniston et al, 2000;Cobb et al, 2003a;Yuan et al, 2004;Wang et al, 2005;Hu et al, 2008;Lorrey et al, 2008), in the assessment of co-seismic uplift rates and earthquake recurrence intervals (Edwards et al, 1988;Zachariasen et al, 1999), in the characterisation of historical storm events (Yu et al, 2004(Yu et al, , 2006aZhao et al, 2009), to establish the timing of episodes of recent coral mortality (Yu et al, 2006b) and in the investigation of settlement patterns in Hawaiian prehistory (Kirch and Sharp, 2005;Weisler et al, 2006). Despite this range of applications, the use of this high-resolution dating technique is still restricted and its potential has not been widely recognised.…”

Human responses to the Younger Dryas in Japan

“…The interglacial-glacial cycles originally predicted by Milankovitch are now proven to coincide with fluctuations in oxygen-isotope signatures (δ 18 O values), recorded in ice cores and marine and terrestrial sediments (e.g., Dansgaard et al, 1993;Hays et al, 1976;Kawamura et al, 2007;Wang et al, 2008;Yuan et al, 2004). In East Asia, recent studies on the oxygen-isotope signatures in cave stalagmites in China (e.g., Sabano and Hulu Caves) have traced millennium-scale fluctuations climatic records reliably furnish climatic frameworks within which changes and variability in adaptive strategies of human societies are legitimately concerned.…”