中国第四纪古气候环境的重建

RECONSTRUCTION OF THE QUATERNARY PALEOCLIMATIC ENVIRONMENT IN CHINA

本文就如何重建第四纪古气候环境问题进行讨论。气候的演化和变更是环境系统中最重要的因素,第四纪冰川作用是反映这一因素中最为重要的事件之一。第四纪沉积物是古气候信息储存的主要场所,因此,系统地研究第四纪地层的地球物理特征、地球化学信息反馈、生物的演替等方面问题极为重要。在此基础上确定其地层的时间尺度、构造运动的程式,以及它们之间的相互关系,加以分析论证,建立起第四纪古气候环境的演化格局。

Recovering and reconstructing paleoclimatic feature is one of important subjects in Quaternary geological events. The problem of Quaternary glacia-tion is still a hot-point of arguement in eastern China for fears. The paper only advances some views on reconstruction of paleoclimate and some problems of Quaternary glaciation in eastern China.Recovering and reconstructing Quaternary climatic pattern must be to process a synthetical and multidisciplinary study for remained and preserved Quaternary stratigraphy in our country, to establish evolution processes of Quaternary climate in various regions, and to recover the paleoclimatic face of our country based on paleoclimatic features in respective regions.Paleoclimatic information is the basic data of reconstructing paleoclimatic environment, including geophysical feature of depositional stratigraphy, feedback of geochemical information, scale of time and space of deposits, evolution of organism, and relation of tectonic movement and stratigraphy.Our research shows that there were mountain glaciers and piedmont glaciers in both western and eastern China, e. g. 'Jingxian period of glaciation', 'Xixiabanma period of glaciation', 'Nieniexiongna period of glaciation', 'Zhumolongma period of glaciation', and'Dali period of glaciation' in western China, and 'Dapai period of glaciation', 'Ponyang period of glaciation', 'Da-gung period of glaciation' and 'Lushan period of glaciation' in eastern China. Whether these period of glaciation between the two areas may compare on time and space is still discussed. However, their ages calculated based on paleomagnetic data arc about 3-2.5 Ma. B. P., 1.8-1.6 Ma. B. P. , 1.1-0.9 Ma. B. P., 0.4-0.2 Ma. B. P. and 0.07-0.01 Ma. B. P respectively.Since the Quaternary period, the Qinghai-Xizang (Tibet) plateau uplifts about 2000-4000 m, and eastern China subsides relatively. It goes without saying that the subsidence quantity of eastern China and the uplift quantity of western China are equal. The relative subsidence quantity of eastern China is about 400-1000 m based on the Quaternary depositional thicknesses in North China and Jianghan plains. In early Quaternary, the Qinghai-Xizang (Tibet) plateau was about 1000 m above sea level and its height was no difference in comparison with that of eastern China, the climatic patterns in the two areas very similar.Since early Quaternary, the world climate turned cold and the Qinghai-Xizang (Tibet) plateau uplifted, which gave a great impact on the climatic pattern of our country. Therefore, the information of climatic change and geomorphological evolution resulting from tectonic movement recorded in the Quaternary strata is necessary for studying and reconstructing the history of Quaternary paleoclimatic change. After analysising these data in detail, the outline of paleoclimatic evolution in the Quaternary period may be drawn.