Pollen record from red clay sequence in the central Loess Plateau between 8.10 and 2.60Ma  

作　　者：MA Yuzhen WU Fuli FANG Xiaomin LI Jijun AN Zhisheng WANG Wei 

机构地区：[1]Key Laboratory of Western China's Environmental Systems (MOE) and College of Resources and Environment, Lanzhou University, Lanzhou 730000, China [2]State Key Laboratory of Loess and Quaternary Geology, Institute of Earth Environment, Chinese Academy of Sciences, Xi'an 710054, China [3]Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China

出　　处：《Chinese Science Bulletin》2005年第19期2234-2243,共10页

基　　金：This work was co-supported by The NSFC Group Funds (Grant Nos. 40121303, 40171094 and 40421101) ；CSA“Hun-dred Talent Projects" (Grant No. Renjiaozi [2000]05).

摘　　要：The Late Miocene and Pliocene are the key periods for understanding the origin and development of the present Asian monsoon circulations and ecologic environ-ments. Here we present a pollen record from Chaona Red Clay section located in the central Loess Plateau in attempt to establish the histories of vegetation and associated climate changes between 8.10 and 2.60 Ma. Our results show that Gramineae-dominated woodland-grasslands developed in this region with Cedrus- and Pinus-characterized montane coniferous forests distributing in higher elevations from 8.10 to 6.73 Ma, probably suggesting a semi-humid climate in a warm-temperate zone. A subsequent expansion of Ulmus- dominated deciduous forests and a synchronous increase of Gramineae-dominated grassland reflect a warmer and more humid climate between 6.73 and 5.67 Ma. The vegetation changed to an Artemisia- and Gramineae-characterized steppe in lower elevations and to a coniferous forest in higher elevations from 5.67 to 3.71 Ma, implying probably a warm and semiarid climate in lowland and hill, and a colder and moister climate in mountain. During this period, a consider-able warmer and more humid climate occurred between 4.61 and 4.07 Ma as indicated by pollen assemblages. The period between 3.71 and 2.58 Ma was characterized by the disap-pearance of Cedrus and Tsuga and also by an abrupt expan-sion of Cupressaceae, reflecting a drastic enhancement of monsoon-related climatic seasonality.The Late Miocene and Pliocene are the key periods for understanding the origin and development of the present Asian monsoon circulations and ecologic environments. Here we present a pollen record from Chaona Red Clay section located in the central Loess Plateau in attempt to establish the histories of vegetation and associated climate changes between 8.10 and 2.60 Ma. Our results show that Gramineae-dominated woodland-grasslands developed in this region with Cedrus. and Pinus.characterized montane coniferous forests distributing in higher elevations from 8.10 to 6.73 Ma, probably suggesting a semi-humid climate in a warm-temperate zone. A subsequent expansion of Ulmusdominated deciduous forests and a synchronous increase of Gramineae-dominated grassland reflect a warmer and more humid climate between 6.73 and 5.67 Ma. The vegetation changed to an Artemisia- and Gramineae-characterized steppe in lower elevations and to a coniferous forest in higher elevations from 5.67 to 3.71 Ma, implying probably a warm and semiarid climate in lowland and hill, and a colder and moister climate in mountain. During this period, a considerable warmer and more humid climate occurred between 4.61 and 4.07 Ma as indicated by pollen assemblages. The period between 3.71 and 2.58 Ma was characterized by the disappearance of Cedrus and Tsuga and also by an abrupt expansion of Cupressaceae, reflecting a drastic enhancement of monsoon-related climatic seasonality.

关 键 词：黄土高原 红泥土 植物进化 季候风 花粉传授 

分 类 号：Q944.43[生物学—植物学]