摘要
本文系贵州威宁草海东南缘喀斯特谷地的南屯泥炭层剖面孢粉研究。剖面深8m,达基岩,采样112块,分析后获孢粉22446粒,有77个科属。根据孢粉组合及^(14)C年龄,该剖面为15000多年来的沉积物。其古植被、古气候可分四个阶段:(1)距今15700—10780年左右,为稀树草丛与以松为主的针阔叶混交林交替出现,反映为3个冷期2个温暖期(莎草多)。(Ⅱ)距今10780—5400年左右,植被由疏树草丛—阔叶树繁茂(莎草由少到多)—阔叶树逐渐减退(莎草很多)—疏林草地.气候相应由开始转暖到温暖湿润及温暖转凉再转寒冷。(Ⅲ)距今5400—700年左右是以针叶树松属为主阔叶树为次的混交林(莎草多)与松林(莎草少)交替出现,气候相应由温湿—温凉干燥……温湿……温凉干燥—温湿—温凉干燥—温湿。(Ⅳ)距今700年左右以来,则以松、栎为主的针阔叶混交林(莎草少)气候温暖较干。根据上述情况,笔者认为以气候开始转暖作为划分更新世与全新世的分界标志,南屯剖面应划在7.15M处,距今10780年左右。其气候期的划分:(Ⅰ)代表晚冰期,(Ⅱ)代表前北方期——大西洋期,(Ⅲ)代表亚北方期——亚大西洋期,(Ⅳ)代表太平洋期。本剖面是贵州晚冰期来比较典型而完整的代表。
This paper deals with sporo-pollen of a Nantun peat-bed section in a karst valley on the southeastern margin of Caohai Lake in Weining County, Guizhou Province. The section is 8m deep, reaching the basic rock. Through analysis, 22446 sporo-pollen grains are gained from 112 samples collected, which belong to 77 families and genera. According to the sporo - pollen associations 14C ages, the sediments of the section are those of many years' since 15000 a. B. P. Its palaeovegetation and palaeoclimate can be divided into 4 developing stages.
Ⅰ. During the years from about 15700 to 10780 a. B. P. , thick growths of grass with sparse trees and mixed conifer and broadlesf forests mainly with pines appeared alternately, showing 3 cold periods and 2 warm periods (With much Cyperaceae).
Ⅱ. During the years from about 10780 - 5400a. B. P. , there was a vegetation of thick
growths of grass with sparse trees-dense broadleaf trees (with cyperaceae from little to much
) -gradual reduction of broadleaf trees (with much Cyperaceae) -grassland with sparse
trees, with the climate correspondingly becoming from warm at the beginning to warm moist and from warm to cool and then to cold.
Ⅲ. During the years from about 5400 - 700a. B. P., the forests (with much Cyperaceae ) mixed mainly with pines and secondly with broadleaf trees and Pinus forests (with little Cyperaceae) appeared alternately, with the climate correspondingly becoming from warm moist-warm cool arid-warm,moist-warm cool arid-warm cool arid-warm moist.
Ⅳ. During the years from about 700 a. B. P. to the present, the conifer and broadleaf forests (with little Cyperaceae) mixed mainly with Pinus and Qvercus appeared, with the climate warm and drier.
The authors consider that the climate which began to become warm should be taken as the boundary sign in demarcating Pleistocene and Holocene. The Nantun section should be marked at the deep point of 7. 15m, about 10780a. B. P. Its climate period should be divided: I stands for
Late Glacial Age, Ⅱ for Preboreal Age-Atlantic Age, Ⅲ for subboreal-Subatlantic Age
and Ⅳfor Pacific Age.
出处
《贵州地质》
1991年第2期141-154,共14页
Guizhou Geology
基金
国家自然科学基金项目
