对鄂霍次克海东南部OS03-1岩芯180 ka BP以来底栖有孔虫内生种Uvigerina spp.进行了稳定氧碳同位素分析,发现了112-109 ka BP(Ⅵ),102-90 ka BP(Ⅴ),85-76 ka BP(Ⅳ),57-54 ka BP(Ⅲ),44-40 ka BP(Ⅱ)和17-10 ka BP(Ⅰ)的6次δ13C轻值事件,其中发生于102-90 ka BP的轻值事件Ⅴ中的δ^13C降幅最大,达到了2.5‰,其他事件中均达到1‰以上. 研究认为,这些δ13C轻值事件可能由表层生产力增高、鄂霍次克海中层水形成减弱、最低含氧带加强等因素共同引起. 古菌生物标志物结果表明,这些δ^13C轻值事件没有受到天然气水合物分解和甲烷气体释放的影响.
AMS14C dating and analysis of grain size,major elements and clay minerals were applied to Core MZ01 from the mud area on the inner shelf of the East China Sea.Based on the environmentally sensitive grain size,clay mineral and major element assemblages,the history of the East Asia winter monsoon since the mid-Holocene could be reconstructed.These three proxies,mean grain size(>9.71μm),chemical index of alteration(CIA)and ratio of smectite to kaolinite in particular,show similar fluctuation patterns. Furthermore,10 extreme values corresponding to the contemporary cooling events could be recognized since the mid-Holocene;these extreme values are likely to have been caused by the strengthening of the East Asia winter monsoon.The cooling events correlated well with the results of theδ18O curves of the Dunde ice core and GISP2,which therefore revealed a regional response to global climate change.Four stages of the East Asia winter monsoon were identified,i.e.8300-6300 a BP,strong and unstable;6300-3800 a BP,strong but stable;3800-1400 a BP,weak and unstable;after 1400 a BP,weak but stable.