[关键词]
[摘要]
文章依据孢粉资料讨论我国西北地区第三纪时期植被的演变情况，认为始新世时古地中海和副古地中海（Paratethys）自南亚及中亚地区的撤退，以及中新世时青藏高原的隆起对东亚季风的屏蔽，都对西北地区的干旱化起了重大作用。上新世中期开始的青藏高原的持续隆起和冬季风（寒流）的劲吹，使本地区植被成分更趋单调．演变成荒漠型植被．气候更趋干旱。根据孢粉资料推测：太平洋季风至少在中中新世已经形成并可伸展至兰州地区，而印度洋季风有可能是同时出现的，并可侵袭到目前的甘肃南部地区。
[Key word]
[Abstract]
Based on palynological data,we suggest that the retreat of the Tethys and Parat ethys from southern and Central Asia in Eocene and the uplift of Qinghai-Xizang Plateau in Miocene have largely shielded the monsoon climate northwestward,and have resulted in the Tertiary aridification in NW China.With the persisting upl ift of Qinghai-Xizang Plateau and the strengthening of winter monsoon(cold sna p)in the Pliocene,the climate in these regions tended to become much drier and the component for vegetations was r...
[中图分类号]
Q914
[基金项目]
中国科学院资源环境领域知识创新工程重要方向项目(KZCX2-YW-105);;国家重点基础研究发展规划项目(2006CB806400);;国家自然科学基金重点项目(40730210)联合资助
