摘要
研究区隶属于典型的东亚季风区,本文基于该区暖和洞4支石笋16个^(230)h年龄和433个氧同位素数据,建立了10.5～0.3kaB.P.东亚夏季风强度时间序列。该序列可划分为3个气候段:1)10.5～5.5kaB.P.时段,东亚夏季风强度较强,峰值落在9.0～5.5kaB.P.;2)5.5～1.0kaB.P.时段,东亚夏季风强度逐步减弱,进入衰退期;3)1.0～0.3kaB.P.时段,东亚夏季风显示增强趋势。该记录反映的全新世季风演化与不同纬度(阿曼、贵州和湖北)的3个洞穴石笋δ^(18)O记录基本一致,表明全新世适宜期在亚洲季风区不存在显著穿时性。暖和洞石笋δ^(18)O值的长期演化趋势追随65°N太阳辐射能量变化,也与Cariaco Basin记录的非洲季风强度变化趋势基本一致(r=0.67),表明ITCZ位置的南北移动可能控制着低纬季风强度的变化,支持"季风是一个环球系统"的观点。
Nuanhe Cave（41°20′N, 124°55′E）locates at Huanren county in Liaoning Province, a typical site influenced by the East Asian monsoon. The climates here are characterized by cold/dry atmospheric circulation during the winter and warm/humid air masses during the summer. The seasonal temperature ranges between -13℃ （Jan.）and 22℃ （ Jul. ）. The mean annual precipitation at the site is between 800ram and 900mm,60% of which falls between June and September. Relative humidity in the cave is 100% （measured on Jun. ,2008 ）and the cave temperature （6℃） keeps constant through a year and approximates a mean annual value.
Four stalagmites（ NH5 ,NH12,NH13 and NH20）were collected in the deep site of the cave. These stalagmites vary from 60mm （ NH13 ） to 157mm （ NH5 ） in length. Their vertical sections are all in candle shapes and the diameters vary between 20 -5dram at the top and 105 - 150mm near the base. Each stalagmite is pure calcite, no porous on the polished surface, and composed of typical coalescent columnar-fabric crystals. Under the binocular microscope,we observed an apparent hiatus at the depth of 14mm in NH13, supported by our dating result that indicates the stalagmite ceased to growth between 3.3kaB. P. and 1.8kaB. P. We also found a hiatus at the depth of 20mm in NH20. We focus our oxygen analysis on the section below the depth of the hiatus. There is no evidence for hiatuses in any other stalazmites.
A composite δ18O profile, pieced all data（ 16 23Fh ages and 433 pairs of oxygen isotope data） measured from the four stalagmites,provides a continuous history of the East Asian Summer Monsoon （EASM）intensity for the period from 10.5kaB. P. to 3.36kaB. P. and 1.9kaB. P. to 0.3kaB. P. （ relative to 1950A. D. ）. The 8180 measurements were run at Isotope Laboratory of Nanjing Normal University with on-line automated carbonate preparation system （ Kiel Carbonate Device）linked to Finnigan MAT-253 ,yielding a standard deviation error of 0.06%. The 23e-Fh dates
出处
《第四纪研究》
CAS
CSCD
北大核心
2011年第6期990-998,共9页
Quaternary Sciences
基金
国家自然科学基金面上项目(批准号:40972111)资助
关键词
暖和洞石笋
Δ18O
东亚夏季风
同相位
全新世适宜期
stalagmite from Nuanhe Cave,δ18O, East Asian Summer Monsoon,in phase, Holocene Optimum
