摘要
通过对东海陆架盆地西南部台北拗陷始新统之瓯江组、温州组和平湖组的孢子和花粉的研究,本区始新统可分为两个孢粉组合:Taxodiaceaepollenites-Caryapollenites triangulus-Aquilapollenites spinulosus组合(早始新世)和Retitricolpites-Retitricolporites组合,后者又分为两个亚组合,分别代表中始新世和中始新世晚期或/至晚始新世早期的孢粉植物群。孢粉组合反映早始新世的植物群主要由杉科、胡桃科和完斗科组成,指示暧湿的、近现今的中南亚热带气候;中晚始新世孢粉植物群具有明显的现代性,并有较多南亚热带成份加入,指示更趋暖热的气候环境,其后半期有较多指示干旱气候的分子出现,表明曾一度受到干旱气候的影响。
In the southwestern Contiuental Shelf Basin of the East China Sea the Eocenerocks about 1250m in thickness revealed by drilling are of marine clasticand carbonate sediments called the Oujiang, Wenzhou and Pinghu Formationsin ascending order, in which abundant marine microfossils have been obtained,including forarninifers, calcareous nannofossils, dinoflageliates, ostracodes asso-ciated with terrigenous sporo-pollen. This paper is a summary report on the paly-noflora from these formations, with two palynological assemblages recognized asfollows: 1.Taxodiaceaepollenites-Caryapollenites triangulus-Aquilapollenites spinulo-sus assemblage (in the lowest part of the Oujiang Formation) This assemblage is characterized by a great number of Taxodiaceaepollenites hiatusand Caryapollenites triangulus, which might amount to as high as about 34% and 30%in content respectively. Other common elements include Pinuspollenites, Abietineae-pollenites, Podocarpidites, Lygodiumsporites, Polypodiaceaesporites,Momipites and Quer-coidites. Those pollen grains with their parent plants unknown or extinct appearin small amount (≤5%), such as Parcisporites, Paraalnipollenites, Momipites trira-diotus, M. triangulus and Aquilapollenites spinulosus. In general characteristics, thispalynoflora is very similar to that of the Tantou Formation in western Henan,which has been assigned to the early Eocene based on both of its vertebrate andspore-pollen assemblages.The Present palynoflora also shows similarities to thatof the Late Sabinian (Early Eocene) from the south or southeastern UnitedStates based on the common occurrence of some pioneer Momipites species. Theseindicate that possibly the triporate pollen of Juglandaceae have undergone parallelevolutionary process in North America and in the Chinese mainland. The presentauthors consider that surely the hypothesis on the evolution of the Momipites-Caryapollenites lineage from the United States in the early Tertiary proposed byNichols and Ott (1978) can well explain the evovlution of the two genera in EastChina. All evidence supports the age of the palynoflora dated as early Eocene,and suggests a warm and humid subtropical climate. 2.Retitricolpites-Retitricolporites assemblage (in the middle--upper part ofthe Wenzhou and Pinghu Formations) This assemblage is different from the first assemblage in the striking decreasein Taxodiaceaepollenites hiatus and Caryapollenites triangulus, and the dominance ofthose pollen grains referred to tricolpate or tricolporate, especially to retitricol-pate or retitricolporate types. In contrast to the first assemblage, this palynoflorashows not only a great abundance but also a high diversity in angiospermouspollen grains. Among them Retitricolpites and Retitricolporites of unknown affinityare most important, reaching to 70--80%, together with Quercoidites, Cupuliferoi-pollenites, Cupuliferoidaepollenites and Cyrillaceaepollenites; in addition, Liquidambar-pollenites, Ulmoideipites, Juglanspollenites and Tiliaepollenites became more commonor began to occur. The main spores of Pteridophyta are Polypodiaceaesporiteshaardti, Lygodiumsporites and Crassoretitriletes nanhaiensis, sometimes reaching31% in total. The gymnospermous palynoflora is mainly composed of such saccateconifers as Pinspollenites, Abietineaepollenites and Podocarpidites; Ephedripites spp.are regarded as of the arid type, becoming a little richer toward the upper partof the Wenzhou Formatlon. The so-called pionner elements such as Momipitestriangulus, M. triradiotus and Aquilapollenites spinulosus disappeared. The presentpalynoflora may be correlated with those from the Middle--Upper Eocene of awide area in China and with the middle Eocene Claiborne palynoflora in NorthAmerica, both being marked by the dominance of tricolpate and tricolporatepollen. According to the associated marine microfossils, this palynoflora is confirmedas belonging to Middle--Late Eocene, and it is believed to have been under awarm and semi-arid, climatic condition. In the upper part of this assemblage.Ephedripites, Nitrariadites and
出处
《微体古生物学报》
CSCD
北大核心
1990年第4期389-402,447-449,共14页
Acta Micropalaeontologica Sinica
