塔里木盆地YJ1X井中奥陶统一间房组燧石结核中的有机壁微体化石

ORGANIC-WALLED MICROFOSSILS IN NODULAR CHERTS FROM THE MIDDLE ORDOVICIAN YIJIANFANG FORMATION,WELL YJ1X,TARIM BASIN,CHINA

位于新疆塔里木盆地塔北隆起的YJ1X井中奥陶统钻遇富含硅质结核的一间房组地层,通过对硅质结核进行切片观察,发现大量丝状蓝藻化石及少数疑源类化石。经鉴定疑源类化石共包括:Aremoricanium sp.,Cheleutochroa oculata,Cymatiogalea sp.,Cymatiosphaera sp.,Dictyotidium microreticulatum,Leiosphaeridia sp.,Polygonium gracile,Pterospermella sp.;丝状蓝藻类化石两属四种,包括:Siphonophycus typicum,S.kestron,S.solidum,Oscillatoriopsis longa;多细胞球状藻类化石1种:Eoentophysalis sp.。其中丝状蓝藻类化石均为奥陶系一间房组的首次报道。该化石组合的发现为塔里木盆地奥陶系一间房组燧石结核中微体化石的研究提供了新资料,大量破碎的藻席及少数疑源类反映了本区沉积环境由浅水相变为深水相的过程。

The Ordovician Yijianfang Formation of the YJ1 X well in Tarim Basin,Xinjiang Autonomous Region,China,contains some laminar and nodular cherts of which a diverse and well preserved microfossil assemblage was disco-vered in thin sections.The assemblage is dominated by 11 genera and 13 species including 8 acritarchs species belonging to 8 genera:Aremoricanium sp.,Cheleutochroa oculata,Cymatiogalea sp.,Cymatiosphaera sp.,Dictyotidium microreticulatum,Leiosphaeridia sp.,Polygonium gracile and Pterospermella sp.,and 4 species in 2 genera of probable cyanobacterias,Siphonophycus typicum,S.kestron,S.solidum and Oscillatoriopsis longa.These filamentous cyanobacterias are first reported in the Yijianfang Formation,which greatly increased the diversity of the Yijianfang Biota.A large number of broken algae mats and a few acritarchs reflect the process of the sedimentary facies from shallow to deep in this area.