摘要
华北石油普查大队过去曾寄来许多采自垣曲系的标本,经我们进行了分析,未在其中找到孢子和花粉。1958年,作者有机会到垣曲工作,当时曾在一些老前辈的指导下,从垣曲系上部采集了一些标本。分析后,仅在最底部的一块标本中发现了比较多的孢子和花粉。所谓垣曲系上部系根据华北石油普查大队的意见划出的,他们用Pg_(2)^(3)的符号表示这一层位。其岩性主要为灰色、灰绿色、淡黄色泥岩、砂质泥岩和泥灰岩等,在其底部有几层薄的褐煤夹层。
In 1958,the writer had a chance to make a trip to the Yuanchu district for the study of the Yuanchu series,and some rock samples from the upper part of this series were collected for palynological investigation.The upper part of Yuanchu series consists mainly of grayish,greenish and light yellowish clays,shales,sandy clays,and at the bottom intercalated with some thin layers of brown coal.Of which only one brown coal has yielded sufficient amount of spores and pollen for the present study.Vegetation of the Yuanchu Series.Spores and pollen of the following plants have been obtained from the brown coal:Polypodiaceae—26.2%,Ginkgo—2.6%,Ginkgoites—2.2%,Podocar-pus—0.45,Pinus—2.2,Picea—0.45,Larix—0.45,Taxodiaceae—6.66,Cupressaceae—11.11,Coniferae—8%,Ephedra—0.9,Carya—0.5,Castanea—6.66,Quercus—10.66,Ulmus—1.33,Magnolia—4%/,Sterculiaceae—0.9,Rosaceae—2.2,Leguminosae—2.65,Cruciferae—1.33,Nymphaeceae—0.9,Gramineae—0.9,3-colpatae—3.13,Cactaceae(?)—0.45 and indeterminable grains—2.26.Spores amount to 26.2%of the total number of microfossils;pollen grains of Gymnospermae-being 35.07%,and those of Angiospermae—38.67%,of the latter herbaceous dements are very few(—6.68%).The writer thinks that,vegetation of Yuanchu at that time was a forest.Because the pollen grains of Angiospermae and Gymnospermae are almost of equality,it would represent a mixed forest.It is very intresting to find that the morphological character of a pollen form is very like that of Opuntia(?)of Cactaceae.Same type of pollen with those of Echinocactus of the same family has been also found in an Upper Eocene bed of Northern Aral by prof.Zaklinskai.Being known that this plant at present only grows at the tropic zone of America.She points out that those plants are the relics of Cretaceous and Paleocene,The writer agrees this veiw.Other interesting fact is that Amentiflorae(such as Salicaceae,Juglandaceae,Betulaceae etc.)and Ulmaceae etc.are almost or completely absent in the Yuanchu complex.As we know that Amentiflorae were the chief components of the Turgai province,named by prof.Kryshtofovich.Absence of these elements would mean that it was a part of Poltavia province of Kryshtofivich.But the essential components of Poltavia,such as Proteaceae,Myrtaceae,Cinamomum,Palmae etc.are also wanting.The reason of this fact has been discussed by krvshtofivich in a paper,he says that“of course,this huge territory is not quite uniform in its flora and could certainly be divided into several subprovinces.”Therefore at that time Yuanchüwas laid on the northern part of poltavia,typical tropical plants in this region were almost lacked.Climate of the Yuanchu flora.Reid and Chamdler have discussed the change in the woody character of the flora in their monograph,and pointed that“……passing from the tropic to the cold region the proportion of woody plants diminishes……it is probable that much of the change in ligneous was due to change of climate.”So that woody character of the flora may reflect the climatic condition.The woody elements in the Yuanchu flora amount to 67%,while the present vegetation of Yuanchu is a forest-steppe,therefore,the climate at that time would be milder than that of the present.Further study the range of every plant for the climatic character is very important.Here the writer only gives a rough and simple discussion.Most of plants listed in the table,grow at present in the south of the Yangtze River,such as,Ginkgoaceae,Carya,Magnolia,Sterculiaceae and Fagaceae(partly),while Podocarpus,Cactaceae(?)and Victoria(?)definitely grow in the tropic.So that,the writer thinks that the Yuanchu flora reflects a sub-tropic rather than a tropic climate,polypodeceous elements may support this view,because polypodeceous plants mainly grow in subtropic zone.Age of Yuanchu flora.Comparing the Yuanchu flora with the Upper Eocene sporo-pollen complexes of Turkman and Aral region studied by Abyzarova and Zaklinskai,the writer found that the typical-tropical elements—Cycadaceae,Gnetales,Lauraceae,Myrtaceae,Proteaceae and Palmae are wanting in the former complex.As we know,the Upper Eocene complexes of Turkman and Aral reflect a tropic-subtropic climate,then the Yuanchu flora would reflect a cooler climate,the age of the Yuanchu flora would be later than the Turkman and Aral flora.It would also be older than Shanwang flora,because the latter is a temperate forest mixed with a few subtropical components.In a word,Yuanchu complex represents a subtropical forest mixed with some tropic elements,therefore,the basal portion of the Upper part of the Yuanchu Series may be dated to Oligocene possibly Lower Oligocene.The writer completely agrees with the view of prof.Y.Y.Young,who has pointed out the mid-upper part of the Yuanchu Series to Upper Eocene-Lower Oligocene,as the writer only studied the upper part of Yuanchu Series,the lower part would belong to Upper Eocene.
作者
宋之琛
SUNG TZE-CHEN(Institute of Geology and Palaeontology,Academia Sinica)
出处
《古生物学报》
1959年第5期27-40,109-112,共18页
Acta Palaeontologica Sinica
