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Last 2000 years changes of climate, sea-level and eolian dusts detected by sedimentologic investigations of brackish lake sediments

咸水湖沉积物沉积学调查发现近2000年气候、海平面和风尘的变化

基本信息

批准号：
07804031
负责人：
FUKUSAWA Hitoshi
金额：
$ 1.47万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

Mineralogical characteristics of last 2000 year records in meromictic lake, Lake Suigetsu, are the indicators of eolian dust concentrations, sea-level and rainfall changes in central Japan. Non-glacial varved sediment in Lake Suigetsu shows that there was no large influx of terrestrial materials into lake basin Sequential chages of illite crystallinity and quartz / illite ratio in late Quaternary fine-grained sediments at Site 794 and Site 795 of ODP Leg 127 of were well correlated to standard records of oxygen isotope change by Prell et al. (1986). This suggests that these parameters are useful to detect eolian dust concentration within sediments. In other words, occurrence of hydrated illite and small concentration of illite suggest that paleosol were greatly formed under wet climate in northern China. Sea-level and rainfall changes were detected by iron mineral composition and chlorite / illite ratio.Investigations show that climatic changes in northern China were parallel to sea-le … More vel changes of the Wakasa Bay in southern part of the Japan Sea. In 250,820,1170,1320,1500 and 1880 A.D., sea-level was risen in the Wakasa Bay when northern China was in wet climate. It is because that Asian monsoon was active in globally warm climate at these times, and that active monsoon took humid atmosphere into northern China. In 250,820,1050-1200,1320,1500 and 1880 A.D., there seems to have been heavy rainfall around Lake Suigetsu with sea-level rising in the Wakasa Bay. This suggests of influxing of Tsushima Current, supplying humid atmosphere and rising of sea-level. In 350-550 and 1350-1400 A.D., preciptations were heavy in the Wakasa region, though there are no rising of sea-level, and dry and cool climate in China.On the basis of mentioned above, there are sea-level rising around the Tsushima Strait and intense influx of the Tsushima Currents into the Sea of Japan before the beginning of warm climate in China and coastal area along the Sea of Japan. This fact sggests that sea-level rising in Tsushima Strait may be a trigger to accelerate intensity of monsoon activity in the East Asia. Less

水越湖近2000年记录的矿物学特征是日本中部风沙浓度、海平面和降雨量变化的指标。Suigetsu湖非冰川化沉积物表明，湖盆没有大量陆源物质流入。ODP Leg 127的794和795站点晚第四纪细粒沉积物中伊利石结晶度和石英/伊利石比值的序列变化与Prell等（1986）的氧同位素变化标准记录具有良好的相关性。这表明这些参数对检测沉积物中的风成尘浓度是有用的。也就是说，水合伊利石的出现和伊利石的低浓度表明中国北方古土壤在湿润气候下大量形成。利用铁矿物组成和绿泥石/伊利石比值检测海平面和降雨量变化。研究表明，中国北部的气候变化与日本海南部若狭湾的气候变化是平行的。公元250年、820年、1170年、1320年、1500年和1880年，若狭湾海平面上升，中国北方气候湿润。这是因为亚洲季风在全球变暖的气候中活跃，活跃的季风将湿润的大气带入中国北方。在公元250年、820年、1050年至1200年、1320年、1500年和1880年，水越湖周围似乎出现了强降雨，若狭湾的海平面上升。这表明对马流的涌入，提供了湿润的大气，海平面上升。在公元350-550年和1350-1400年，若狭地区降水较多，但没有海平面上升，中国气候干燥凉爽。综上所述，在中国和日本海沿岸地区气候开始变暖之前，对马海峡周边海平面上升，对马流大量涌入日本海。这一事实表明，对马海峡海平面上升可能是加速东亚季风活动强度的触发因素。少