in Jurassic and Cretaceous Stratigraphy

Earth Science Frontiers, Vol. 17, Special Issue, Aug. 2010 ISSN 1005-2321
228
A Early Jurassic Flora from Southern Jilin, China
Chunlin Sun 1 , Tao Li 2 , Lijun Zhang 3
1. Key-Lab for Evolution of Past Life and Environment in Northeast Asia, Ministry of Education, Research Center of Paleontology and
Stratigraphy of Jilin University, Changchun 130026, China (E-mail: clsun@jlu.edu.cn)
2. Geologic Museum of Jilin University, Changchun 130026, China
3. Bureau of fossil protection and administration of Liaoning , Shenyang 110032, China
A diversity Early Jurassic flora was preserved in
the fine-grained sandstone and siltstone beds from the
middle-upper part of the Yihe Formation in the Yihe
Basin, southern Jilin, China. The Yihe Formation is
represented by fluvial and swamp sediments, consisting
of conglomerates, sandstones, siltstlnes, and thin coal
layers.
The Yihe flora is composed of 35 species
belonging to 22 genera, containing Equisetales: Equi-
setum laterale Phillips,Neocalamites carrerei (Zeiller)
Halle, N. hoerrensis (Schimper) Halle, N. cf . rugousus
Sze, Annulariopsis sp. Filicales: Marattiopsis hoerensis
(schimper) Thomas, Coniopteris sp. 1, Coniopteris sp.
2, Clathropteris obovata Öishi. Filices incertae sedis:
Cladophlebis nebbensis (Brongniart) Nathorst, Clado-
phlebis tersus Chang, Cladophlebis sulktensis var.
crassa Brick, Cladophlebis sp. Bennettiales: Ptero-
phyllum baotoum Zhang, Pterophyllum exhibens Li,
Pterophyllum propinquum Goeppert, Perophyllum cf.
tietzei Schenk, Pterophyllum sp., Anomozamites sp.,
Tyrmia? aequalis Liu et Mi, Cycadolepis corrugata
Zeiller. Nilssoniales: Nilssonia inouyei Yokyama, N.
orientalis Heer N. sp. Cycadales: Ctenis chinensis Hsu,
Ctenis sp. Ginkgoales: Ginkgo digitata (Brongniart)
Heer, Baiera cf. concinna (Heer)Kawasaki, Glosso-
phyllum? sp. Czekanowskiales: Phoeniopsis sp. Coni-
ferales: Storgaardia pityophylloides Liu et Mi,
Podaozamitalis: Podaozamites sp., Lindleycladus
lanceolatus (Lindley et Hutton.) Harris. Semina: Car-
polithus sp. Form genus incertae sedis: Taeniopteris cf.
tenuinervis Braun.
The flora is dominated by cycads and ferns.
Among cycads, the most of genera have been found
from the Early Jurassic foloras of the North and South
China except for Siberia and the northern part of
Northeastern China. Based on comparisons with sub-
tropic or tropic floras from the southern China, some
typical genera of cycads, for instance Ptilophyllum,
Otozamites, are absent in the present flora. Ferns
possesses a higher percentage in the present flora,
especially the occurrence of Clathropteris seems to
indicate a warm and humid climate, but compared with
the those of the subtropic and tropic floras the com-
ponents of Dipteridaceae are not abundant. Ginkgos
and Czekanowskiales with a low-diversity showing
seasonal change of climate also occur in the present
flora. The more abundant Neocalamites of horsetail
shows relatively complete fragmentation suggesting it
grew close to the depositional site. Sedimentological
characteristics and the composition of the flora signifi-
cantly indicate a relatively warm and humid palaeo-
climate for the Yihe Basin Early Jurassic.
The age of the Yihe flora has been generally
accepted as Early Jurassic (Liu and Mi, 1981, Bureau of
geology and mineral resources of Jilin, 1982). Although
the Yihe flora contains some taxa that are long ranging
through Late Triassic to the Jurassic in Eurasia, the
occurrence and low-diversity of Coniopteris offers an
evidence supporting a late Early Jurassic age. This
genus is long ranging (late Early Jurassic to Late
Cretaceous) in the Northern Hemisphere, but it begin to
occur in the late Early Jurassic and diverse in the
Middle Jurassic, absent in the early Early Jurassic. Only
two incomplete specimens of Coniopteris were
collected from this flora. It is a significant component
for us to regard the age of the present flora as late Early
Jurassic.
The present flora is similar to the those of Early
Jurassic floras distributed in the North China and
Middle Asia, such as Fuxian flora from Northern
Shanxi, Yongdingzhuang flora from Datong, Shanxi,
Wudanggou flora from Inner Mongolia, The flora of the
upper mumber of Beipiao Formation from Western
Liaoning, Tianshuigou flora from Northeastern border
of Qaidam Basin, Qinghai and Aksaisk flora from
Issyk-kul Basin, Sandjia flora from Gissar, Kokkija
flora from Eastern Fergana, Sarikamish flora from
Northern Fergana, Dzhil flora from Northern Kirgizija.
Acknowledgements: Supported by Project 111 of
China.
Key words: Southern Jilin; Early Jurassic; Flora
References:
Bureau of geology and mineral resources of Jilin
Province. Regional geology of Jilin Province.
Beijing: Geological Publishing House, 1988: 1-
698 (in Chinese).
Bureau of geology and mineral resources of Jilin
Province. Stratigraphy (Lithostratic) of Jilin
Province. Wuhan: China University of Geo-
sciences Press, 1997: 1-324 (in Chinese).
Genkina R.Z. Older Mesozoic flora and stratigraphy