Investigation on trigger of Asian monsoon intesities by using lake, shallow-sea and loess sediments

利用湖泊、浅海和黄土沉积物研究亚洲季风强度的触发因素

基本信息

批准号：
11304033
负责人：
FUKUSAWA Hitoshi
金额：
$ 19.55万
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 (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

项目摘要

There are often well-preserved varved sediments in maar lakes of western Europe and brackish-water lakes of Japan. Many chronological and sedimentological studies for high-resolution reconstruction of climatic and paleoenvironmental changes since Last Glacial have been carried out by using these varves. In particular, accurate chronology and high-resolution changes of the paleoenvironment reconstructed by using varved sediments since 102,000 yrs BP at Lago Grande di Monticchio, Italy (Zolitschka and Negendank, 1999) and since 45,000 yrs BP at Lake Suigetsu, Japan (Kitagawa and Van der Plicht, 1998 ; Fukusawa, 1999) has attracted scientific attention in Quaternary research.We hope to investigate triggers and birth place of global climatic changes on ocean and atmospheric circulations. Because there are several big questions on global climatic system in earth science field. One of these questions is "Where have given first impact to climatic system as a trigger?" Blunier et al. (1998) sh … More ows interrelationships among ice core data in Greenland and Antarctica presenting. Abrupt climatic changes during Last Glacial in Antarctica ice core seem to go ahead of those in Greenland (Blunier et al., 1998). Now, place of dispatch on global climatic change are presumed 3 main sites by many researchers as follows ; North Atlantic as birth place of ocean belt conveyor, Antarctica as ice volume product area, and low latitude area of West Pacific as warm pool. Our research will give many information to discuss whether warm pool of western Pacific is birth place or not. Because Asian monsoon intensity are controlled by magnitude of sea surface temperature in low latitude area of West Pacific and of snow covered area on the Himalayan / Tibetan Plateau in winter season. Research of varved lacustrine sediments in East Asia will give many information to solve our questions through detection of Sediment flux (mg/cm 2yr). We calculated accurate and high-resolution sedimentation rate on the base of varve counting in Lake Suigetsu varve. According to eolian illite and quartz fluxes in varved sediments, decreasing of dust flux due toexpansion of vegetation in dust source area such as Chinese Loess Plateau occurred since 15,500 years BP. However, stratified water massin summer at Lake Suigetsu appeared since 14,000 years BP, because main componets of iron minerals transported from Mn-rich vivianaite to siderite. Also, Organic carbon flux due to increasing primary production in surface water have increased since about 16,000 years BP. These facts indicate that vegetation in the inland area of Asia expanded before primary production increased in Lake Suigetsu. Four paleodimate records are roughly similar, but not in detail. Abrupt decreasing of eolian dust flux occurred in varve sequence of Japan was more quickly than increasing of delta 1 80 changes in GISP2 in the onset of the Boiling warm period except Pre-Boreal, and also decreasing rate was more quickly in the onset of the Younger Dryas period. Organic carbon flux originating from primary productions by phytoplankton increased since 16,000 years BP, though warming in water mass of Lake Suigetsu. These evidences give us three important paleoclimatic information as follows ; 1)Warm and humid climate by Asian summer monsoon expanded from Japanese Islands to the inland area of China since 16,000 years BP. 2) Abrupt onset of warming climate in inner area of Asian Continent occurred more quickly than that of GISP2 ice core with time lags more than 1,000 years. 3) Trigger of global changes was located at low latitudes rather than high latitudes around Greenland ice sheet because of existence of climatic changes at low latitudes prior to at high latitudes. Also, third evidence supports Prof. Wang Linglang's theory (Wang et al., 1999) about birth place of climatic impact to global changes. His theory suggests that changes of warm pool in West Pacific gave initial impact to global changes. Less

西欧的玛珥湖和日本的咸水湖中经常有保存完好的沼泽沉积物，许多年代学和沉积学研究都是利用这些沼泽来重建末次冰期以来的气候和古环境变化。利用距今 102,000 年以来的变化沉积物重建了大湖古环境的具体、准确的年代学和高分辨率变化意大利蒙蒂奇奥（Zolitschka 和 Negendank，1999）以及距今 45,000 年的日本水月湖（Kitakawa 和 Van der Plicht，1998；Fukusawa，1999）在第四纪研究中引起了科学界的关注。我们希望调查触发因素和诞生地因为全球气候变化对海洋和大气环流有几个大问题。地球科学领域的气候系统问题之一是“气候系统的触发因素在哪里？”Blunier 等人（1998）揭示了格陵兰岛和南极洲冰芯数据之间的相互关系。末次冰期期间，南极洲冰芯的变化似乎领先于格陵兰岛（Blunier et al., 1998）。许多研究人员推测气候变化的三个主要地点：北大西洋为海洋带式输送机的诞生地，南极洲为冰量生成区，西太平洋的低纬度地区为暖池。讨论西太平洋暖池是否是诞生地，因为亚洲季风强度受西太平洋低纬度地区和喜马拉雅/青藏高原冬季海表温度大小的控制。的东亚的湖泊沉积物通过沉积物通量（mg/cm 2yr）的检测可以提供许多信息来解决我们的问题。我们根据风积伊利石对水月湖的沉积物进行计数，计算出准确且高分辨率的沉积率。黄土高原等沙源区15500年来，由于植被扩张导致沙尘通量减少然而，自距今14,000年以来，水月湖夏季出现分层水体，因为铁矿物的主要成分从富含锰的菱铁矿转移到菱铁矿，而且自大约距今16,000年以来，由于地表水中初级生产力的增加，有机碳通量也有所增加。这些事实表明，在水月湖初级生产力增加之前，亚洲内陆地区的植被扩张，四个古地酸盐记录大致相似，但不详细。除前寒带外，日本varve序列中风尘通量的突然减少速度快于沸腾暖期开始时GISP2 delta 1 80变化的增加速度，且在雅戈尔期开始时减少速度也较快尽管水月湖水体变暖，但自距今 16,000 年来，源自浮游植物初级生产的有机碳通量有所增加。这些证据为我们提供了三个重要证据。古气候信息如下： 1）自距今16000年起，亚洲夏季风带来的温暖湿润气候从日本列岛扩展到中国内陆地区；2）亚洲大陆内陆地区气候突然开始变暖。比GISP2冰芯滞后1000多年3）全球变化的触发点位于格陵兰冰盖周围的低纬度地区而不是高纬度地区。因为低纬度地区先于高纬度地区存在气候变化。此外，第三个证据支持了王令浪教授关于气候影响全球变化的发源地的理论（Wang et al., 1999）。他的理论表明，温暖的变化。西太平洋的水池对全球变化的影响较小。