摘要
本文对南京东郊徐家山剖面12块样品中所发现的孢粉及疑源类进行了分析研究,共发现孢粉31属、47种,疑源类17属、41种(包括9新种)。按其所含孢粉属种及含量特征认为:下青龙组及上青龙组的地质时代属早三叠世。结合出现的菊石及牙形刺进行分析,下青龙组四段的地质时代属早三叠世Nammalian期;上青龙组的地质时代属早三叠世spathian期。按疑源类属种及含量特征自下而上明显地划分出组合带Ⅰ、Ⅱ和Ⅲ,分别与下青龙组四段、上青龙组一段及上青龙组二段相对应。根据疑源类各带特征推测:下青龙组四段为平静、近岸的海相沉积;上青龙组一段沉积时的海水较为动荡,且气候亦较温暖;上青龙组二段沉积时的海水平静,且水体较先前要深。
In southern Jiangsu, the Lower Triassic is widely developed and can be divided ascendingly into the Lower and Upper Qinglong Formations. The materials dealt with in the present paper were obtained from the Xujiashan section, in the suburbs of Nanjing. This section is exposed, with Member 4 of the Lower Qinglong Formation and two members of the Upper Qinglong Formation observable. Among the 18 samples taken from this section, 12 samples contain more or less palynomorphs including about 47 species in 31 genera, and acritarchs including 41 species in 17 genera.
1. Assemblage of Member 4 of Lower Qinglong Formation
This assemblage is characterized by the dominance of acritarchs, which attain 96.1% of the total number; the fern spores only amount to 0.9% and the gymnospermous pollen grains to 3%. The composition of this assemblage is listed as follows:
Sporopollen: Punctatisporites sp. 2, Calamospora? sp., Cycadopites follicularis, Chasmatosporites sp., Monosulcites sp., Pityosporites sp., Alisporites sp., Pteruchipollenites el. reticorpus, Ellipsovelatisporites plicatus, Pinuspollenites latilus, Podocarpidites sp. 2, Protopicea sp., etc..
Acritarchs: Granodiscus granulatus. Leiosphaeridia jiangnanensis su. nov., L. linebacki, L. obrculata, Ls spp., Verrucosphaera spp., Filisphaeridium simiplex sp. nov., Psiloschizosporis circularis, etc., amoung which Leiosphaeridia jiangnanensis amounts to 93.9% the total number of acritarchs.
The ammonites found in this formation were identified as Paranonites and Anasibirites.
Based on the ammonites and sporopollen, Member 4 of the Lower Qinglong Formation has been assigned to Early Triassic, which was considered as equivalent to Late Nammalian. From the Acritarchs, it can be seen that the then depositional environment might be shallow marine in southern Jiangsu.
2. Assemblage of Upper Qinglong Formation
This assemblage is also characterized by the dominance of acritarchs, which attain 91.2% in total; the fern spores amount to 2.1% and gymnospermous pollen to 6.7%. The priinoipal elements include:
Sporopollen: Leiotriletes sp., Calamospora? sp., Concavisporites sp., Puctatisporites minutus, P pistlus, P. sp. 1, Cyclogranisporites congesttts, C. spp., Multinodisporites sp., Endosporites anmiaoensis, Aratrisporites spp., Cycadopites mininus, C. follicularis, C. sp., Chasmatosporites triquetus, C. sp., Monosulcites sp., Marsupipollenites? sp., Ephedripites sp., Pityosporites sp., Alisporites parvus, A of. nuthallensis, A. sp., Vitreisporites sp., Pteruchipollenites cf. reticorpus, Pinusporites? sp., Podocarpidites spp., Protopicea sp., Abiespollenites cf. cylvetritypus, Cordatina sp, Chordasporites sp., Jugasporites nubilus, Limitisporites sp., Lueckisporites tattooensis, Protohaplixypinus sp., Stritoabietes cf. sedovai, Striatopodocarpites sp., Taeniaesporites cf. transversundatus, T forris, T. sp., etc..
Acritarchs: Granodiscus granulatus, G. spp., Leiosphaeridia jiangnanensis, L. linebacki, L. hyalina, L. obiculata, L. spp., Verrucosphaera spp., Dictyotidium cohora, D. sp., Baltisphaeridium spp., Filisphaeridium simplex sp. nov., F. decorosum sp. nov., Micrhystridium jiangsuense sp. nov. M. stellatum, M. spp., Gorgonisphaeridium condensum, G. sp., Solisphaeridium sp., Lophosphaeridium cf. magnum, Veryhachium xujiashanense sp. nov., V. callicomum sp. nov., V. stallatum sp. nov., V. minor, V. cf. colemanii, V. cf. formosum, V. spp., Pterospermella sp., Psiloschizosporis parvus, P. circularis, Schizosporis microreticularis, S. sp., Hungarodiscus? pallidius sp. nov., H. sp., Tasmanites nanjingensis sp. nov. and Dactyofusa sp., together with 3 types of indeterminable dinoflagelates.
Also found in the same formation were the ammonites identified as Columbites and the conodonts as Neospathoudus and Cypridodella.
Therefore, this formation can be regarded as Early Triassic in age, which was considered as equivalent to the Spathian. Based on the acritarchs the formation is of marine deposits.
出处
《古生物学报》
CAS
CSCD
北大核心
1991年第4期458-479,551-554,共22页
Acta Palaeontologica Sinica
关键词
孢粉
疑源类
三叠纪
青龙组
Sporopollen, Acritarchs, Lower Qinglong Formation, Upper Qinglong Formation, Suburbs of Nanjing
