检索规则说明:AND代表“并且”;OR代表“或者”;NOT代表“不包含”;(注意必须大写,运算符两边需空一格)
检 索 范 例 :范例一: (K=图书馆学 OR K=情报学) AND A=范并思 范例二:J=计算机应用与软件 AND (U=C++ OR U=Basic) NOT M=Visual
机构地区:[1]北京市地质研究所
出 处:《北京地质》1994年第4期1-7,共7页Beijing Geology
摘 要:北京─通县平原地区的第四纪环境演变,主要取决于气候变化和新构造运动。早更新世时,古永定河尚未形成自西向东穿越本区的河道,新构造运动和海平面变化,控制和影响了海侵事件的规模和范围。中更新世本区湖沼广布。晚更新世是本区平原化的主要时期,塑造了北京平原现时地貌的基本格架。晚更新世末,受末次冰期气候的影响,本区发生了地史时期的最后一次大事件,造成了物种迁移和绝灭,全区广泛发育黄土堆积。进入全新世,本区环境变化以河流作用最为显著,沉积物主要分布在各大水系的河谷中,构成一、二级阶地和近代河床与河漫滩淮积。The environmental evolution of Quaternary of Beijing-Tongxian Region mainly depends upon the neotectonics and palaeoclimatic changes, which controlled and influenced the distribution, evolution of depositional areas and uplifting erosional areas and changes of sedimentary types, and also the scale and scope of Quaternary transgressions. In early Pleistocene, Palaeo-Yongding River had not formed a channel crossing the region from west to east. In middle pleistocene there were widespread lakes and swamps. Late Pleitocene was the essential duration for the plaiation of the region , when the basic framework of the present geomorphology of Beijing Plain was constructed. At the end of late pleitocene, influenced by the climate of glacier period, the last great event of the region in the geological time was taken place so that the migration and extinction of organism species were resulted, loess accumulation was generally developed throughout the whole region. In Holocene, the most important environmental change was fluvial process, which was still influnced by two factors-neotectonics and palaeoclimatic changes.
分 类 号:P534.63[天文地球—第四纪地质学] X141[天文地球—古生物学与地层学]
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在载入数据...
正在链接到云南高校图书馆文献保障联盟下载...
云南高校图书馆联盟文献共享服务平台 版权所有©
您的IP:216.73.216.249