东疆北部全新世气候不稳定性的湖泊沉积记录

 对新疆东疆北部巴里坤湖2.5 m深的沉积剖面进行了年代学、沉积物粒度、TOC、磁化率和CaCO₃含量分析,对比研究确定了巴里坤湖的碳库年龄约为750 a,据此建立了研究剖面的年代序列。研究表明,各气候代用指标序列揭示了巴里坤湖地区全新世期间存在多次干湿气候波动,并伴随着一系列突发气候事件,其中有6次事件可以与全新世北大西洋浮冰碎屑事件及GISP2冰芯氧同位素记录进行良好对比,且呈现出显著约1.6 ka的变化周期,表明高纬度北大西洋地区的气候变化可能通过对西风环流的影响与中国西北干旱区的气候变化密切相关。谱分析揭示出研究区气候变化还具有显著的200 a,133 a,108 a和77 a周期,可能与太阳活动周期有关。6300—5200 cal a BP和4300—3500 cal a BP期间巴里坤湖地区气候较为干旱,结合广泛的区域对比认为,中全新世干旱事件具有普遍性。

Holocene Climatic Instability Recorded by a Lake Sediment Section in Northeast Xinjiang, China

Based on the analyses of the chronology, grain size, TOC, susceptibility and CaCO3 from a sediment section in Barkol Lake, northeast Xinjiang, and combining with the previous studies, the dead carbon effect was confirmed at ca 750 a in Barkol Lake. Study results indicated that Holocene climate in northeast Xinjiang of China has been alternating between cold (or cool) /wet and warm/dry conditions, and was punctuated with a series of abrupt climate shifts. Abrupt climate shifts revealed by all proxies occurred at ca 1.3, 3.0, 4.3, 5.6, 8.0, 8.6 cal ka BP, which can correlate well both to the abrupt shifts recorded in the North Atlantic Ocean (NAO) and the GISP2 oxygen isotope record. The correlation indicates that the climatic changes in the extreme arid NW China were associated with the NAO, probably via the North Atlantic Oscillation-affected westerly winds. The strength and position of westerly winds probably modulate the Siberian-Mongolian high-pressure system (winter monsoon), and directly influence the climate in China. Moreover, an evident Middle Holocene drought interval is also revealed by all proxies, and the so-called mid-Holocene Climatic Optimum in China needs further study.