Framework of environmental changes in East Asia during the past 20 ka

为了弄清过去20ka以来长江三角洲、中扬子地区、黑河下游、塔里木盆地和准噶尔盆地、中国和关东平原、佐贺平原、鹿儿岛湾和北海道南部的环境变化格架。在以干湿交替为主的内陆中国，17~18ka和13~12ka为高沙泥供应阶段，同时是活动沙丘和尘埃形成阶段，对应于南极冰芯的尘埃高峰(Petit et al.，1999)。在日本关东和北海道南部，全新世的基底砾层(HBG)将与年轻仙女木事件有关。高温在日本和东部中国，快速升温和海平面上升在10ka左右开始，对应于高温早期。这一海平面快速上升阶段被Alley等人(1997)约8.0~8.4ka的短暂海平面下降中断(近8.2ka事件)细分为两个阶段。有必要理解从10ka.d到5.5ka.d的整个高温。中世纪暖期到小冰期在中世纪暖期，中国的气候比较干燥和温暖，但在中世纪末期和小冰期最早的阶段，长江中游的水位突然上升。在黑河下游，旧航道废弃，新航道入湖。掌握地球各地，特别是陆地地区，包括大陆内陆和边缘地区发生这些重大事件的时间，将有助于弄清环境变化、环境变化的机制、迁移和规模等方面尚未解决的问题。

In order to clarify the framework of environmental changes during the past 20 ka, in Yangtze Delta, middle Yangtze area, lowest reaches of Heihe, Tarim Basin and Jungar Basin, China, and Kanto Plain, Saga Plain, Kagoshima Bay, and south Hokkaido, Japan.a. MIS2In the inland China, where alternation of wet or dry conditions is the most important, 17-18 ka and 13-12 ka were the stage of high sand and mud supply, at the same time that of active dune and dust formation, corresponding to dust peaks in Antarctic ice cores (Petit et al.,1999).b. Younger DryasIn Kanto and south Hokkaido, Japan, basal gravelly layer (HBG) of the Holocene will be relevant to the Younger Dryas event.c. HypsithermalIn Japan and east China, quick warming and sea level rising starts around 10 ka, corresponding to early phase of the Hypsithermal. This stage of rapid sea level rising is subdivided into two by the interruption of short lowering of sea level about 8.0 to 8.4 ka, nearly 8.2 ka event by Alley et al.(1997). It is necessary to understand whole Hypsithermal from 10 to 5.5 ka.d. Medieval Warm Period to Little Ice AgeIn the Medieval Warm Period, it is much drier and warmer in China, but in the latest Medieval Period and earliest phase of the Little Ice Age, river water level of Yangtze River increased suddenly in the middle reaches of the river. In the lowest reaches of Heihe, old channels were abandoned and new channels supplied water into new lakes.To grasp the timing of such important events in various part of the earth, especially in terrestrial areas, including inland and marginal areas of the continent, will contribute to make clear the unsolved problems in environmental changes, its mechanism, migration, magnitude and so on.