摘要
河南西部义马常瑶、东韩沟一带分布有一套红色碎屑岩地层,1983年笔者首次发现了一批介形类、轮藻,一枚假鳄类牙齿和一些植物化石,为该区地层的划分对比提供了新的依据。该区的地层自上而下划分如下:1.石千峰群:可进一步分为三个组(自下而上):(1)孙家沟组(P_(2s)):底部为灰白、黄白色厚层粗粒砂岩;中部为灰绿、黄绿色粉砂质泥岩夹灰白、棕黄色长石石英砂岩;上部为灰绿色长石石英砂岩和紫红色泥岩夹泥灰岩。厚291.5米。在该组中部含有少量双壳类:Abiella sp.和 Microdontella sp.等。其时代认为属晚二叠世。(2)刘家沟组(T_(11)):为紫红色长石石英砂岩夹砖红色泥质粉砂岩、泥岩和含砾粗砂岩。厚158.9米。该组在本区未发现化石,但根据山西刘家沟组中所发现的交城肋木 Pleuro-meia jiaochengensis 和 Lundbladispora-Taeniasporites-Cycadopites 孢粉组合及叶肢介 Leptolimladia 等化石,其时代属早三叠世。
A strata of red clastic rock are distributed in the changyao and donghangou of the yima area,west Henan Province.The ostracods, charaphytes,a tooth of pseudosuchia and fossil plants have been first found by outher in this area in 1983,these fossils furnish fresh evidence with comparison and divsion of this strata.The strata of this area are divided in ascending order as fllows: 1.Shiqianfeng Group:It is subdivided in three formation(ascending order as follows). (1)Sunjiagou Formation(p_2s):The basal part is dominated by thick-bedded greyish white,yellowish white coarse sandstone. The middle part consists of greyish green and yellowish green silty mudstone,intercalated with greyish white and brownish yellow felds- parthic quatziferous sandstone.The upper part is greyish green felds- parthic quatziferous sandstone and purplish red mudstone,intercalated with muddy limestone.Thickness is 291.5m.The middle part of this formation contains small amounts of bivalves listed below.Abiella sp.and Microdontella sp.ect.The age of this formation is considered belong to the Late permian. (2)Liujiagou Formation(T_):This for marion is composed of purplish red feldspartic quatziferous sandstone,interalated with scar- let muddy siltone,mudstone and conglomeratic coarse sandstone-Thi- ckness is 15,ais formation is non found fossil in this area,but accoding to fossils plants Pleuromeia jiaochengensis and sporo-pollen Lund- bladispora-Taeniaesporites-Cycadopites assemblage as well as esteria Leptolimnadia are found in the Liujiagou Formation of Shanxi pro- vince.Its age is considered belong to the Early Triassic. (3)Hoshanggou Formation(T_(1h)):This formation consists of scarlet silty mudstone and muddy siltstone,intercalated with medium- fine feldsparthic quatziferous sandstone,greyish green mudstone and calcareous mudstone as well as muddy limestone.Thickness is 227.7m In the basal part and upper part of this formation have been found ostraeods,charaphytes,fossil plants and a tooth of Pseudosuchia. The ostracoda assemblage is characterized by Darwinula triassiana- D.fengfengensis-D.rotundata,including 8 species listed below.Darwinula triassiana Belousova,D.fengfengensis Pang,D.rotundata Lübimova,D. recondita Mandelstam,D.pseudoinornata Belousova,D.aff.accepta Lübimova,D.aff.promissa Lübimova,D.zouzhigouensis(sp.nov.)This assemblage is closelv similar in appearance to the assemblage Darwi- nula triassiana-D.parva of the Early Triassic in the Basins Shaanxi- Gansu-Ningxia.The charaphyta is dominated by Stellatochara and Stenochara,mainly including 5 genus 7 species,but Auerbachichara and Altochara are non found.Its age belongs to the Early Triassica.A tooth of Pseudosuchia is ascertained Xilousuchus sapingensis Wu in the Hes- hangou Formation of the Eerly Triassic,Shaanxi province.The plant fossils consists chiefly of Pleuromeia sternbergi-P.rossica assemblage resembling those of the Early Triassic flora in the Heshanggou Forma- tion,Shanxi Province. To sum up,the age of the Heshanggou Formation belongs to the Early Triassc. 2.Ermaying Formation(T_2er):The lower part consists of greyish green feldspartis quatziferous sandstone,intercalated with purple silty mudstone.The middle part is marked by purple siltstone and silty mudstone,intercalated with thin-bedded feldspartic quatziferous sandstone and greyish green calcareous mudstone.The upper part com- prises blownish yellow and yreyish white feldspartic quatziferous sandstone aternationg with purply mudstone,silty mudstone and silts- tone,intercalated with greyish green calcareous mudstone.This for- mation yields obundant ostracods and charaphytes.Thickness is 609.1m. The ostracoda assemblage is predominated by Lutkeyichinella-Darwinula chiefly including 2 genus 7 species list below.Darwinula tersiensis Mandelstam,D.oblonga Schneider,D.subovatiformis Su et al,D.arta Lübimova,D.sp.,Lutkevichinelia minuta Su et al,L.sublongovata(sp.nov.), L.yimaensis(sp.nov.).This assemblage is largly eqivalent to the ostracoda in the Middle Triassic Ermaying Formation fron Shaanxi Province, and Lower-Middle Triassic in the USSR,The charaphytes are predomi- nated by Stellatochara,next Stenochara,Cuneatochara,Porochara,Altochara and Vladimirella,including 20 species.This charaphyta assemblage is closely similar in appearance to the Middle Triassic charaphyta of China,USSR,south Germany and south Sweden.Therefore,the age of the Ermaying Formation should be to the Middle Triassic At the last,the nresent paper is carried on to describe systemati- cally 2 genus 15 species of ostracods collected the Heshanggou Formation and Ermaying Formation.2 plates are added in the end.
