共和盆地剖面第四纪孢粉组合特征及环境演化  

QUATERNARY SPOROPOLLEN ASSEMBLAGES AND ENVIRONMENTAL EVOLUTION OF THE GONGHE BASIN ON THE NORTHEASTERN MARGIN OF THE QINGHAI-TIBET PLATEAU

作　　者：施炜[1] 马寅生[2] 吴满路[2] 杜建军[2] 张西娟[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083 [2]中国地质科学院地质力学研究所,北京100081

出　　处：《地质力学学报》2004年第4期310-318,共9页Journal of Geomechanics

基　　金：国土资源大调查项目"黄河上游新构造活动与地壳稳定性调查研究"(编号:200012400103)。

摘　　要：青藏高原东北缘共和盆地沉积了较厚的第四系,详细地记录了共和盆地第四纪环境变化。通过对共和盆地第四系沉积序列特征和孢粉组合特征的分析,结合热释光测年,本文较详细地研究了共和盆地第四纪以来的环境变迁,并将其分为两大阶段:早期为湖相沉积阶段(中更新世晚期～0 079Ma),气候相对温和。晚期为河流和风成沉积阶段(79 2ka～至今),气候相对干旱。早期阶段又可进一步划分为三个气候期和五个气候亚期。总体上,共和盆地自早更新世以来由偏湿气候逐渐转变为干旱气候,古植被由森林植被逐渐转化为森林草原型植被。其主要原因可能是早更新世以来青藏高原强烈隆升,改变了西南季风气候格局所致。Relatively thick Quaternary strata are deposited in the Gonghe basin on the northeastern margin of the Qinghai-Tibet Plateau.They record Quaternary environmental changes in the basin in details.On the basis of an analysis of the characteristics of Quaternary depositional sequences and sporopollen assemblages in the Gonghe basin,combined with the thermoluminescent dating,the authors have studied the environmental change in the basin since the Quaternary and divided the change into two major phases:the early phase was one of lacustrine sedimentation(from the late part of the middle Pleistocene to 0079 Ma),when the climate was relatively warm,and the late phase was one of fluvial sedimentation and eolian sedimentation(from 972 ka to the present),when the climate was relatively dry.The early phase may be further divided into three climatic stages and five climatic substages.Generally,in the Gonghe basin the climate has turned gradually from slightly warm to dry and the paleo-vegentation has changed gradually from forest vegetation to forest-steppe vegetation since the early Pleistocene.The main cause for this change is possibly that strong uplift of the Qinghai-Tibet Plateau since the early Pleistocene may have changed the southwest monsoon climatic pattern.

关 键 词：第四纪 共和盆地 第四系 孢粉组合 环境演化 青藏高原 湖相沉积 早更新世 古植被 中更新世 

分 类 号：P534[天文地球—古生物学与地层学] P467[天文地球—地质学]