中国湖北秭归县庙河村早寒武世天竺山段的硅化微体化石

描述了湖北秭归县庙河村寒武系最底部(天竺山段)硅化微体化石13属16种,并论述了其地层意义.所有微体化石皆见于燧石切片中,此组合含大量小个体的具刺凝源类,以Micrhystridium ampliatum Wang为主,并与Paracymatiosphaera spp.,其它球形分子Lelosphaeridia,Favososphaeridium,Eoaperturilites及丝状体Obruchevella 和Megathrix共生,此地真正的陡山沱组是以含大量的和形态复杂的疑源类及简单的丝状体和球状化石为特征,这两个可靠的微体化石组合的发现和区分对本区及邻区震旦系-寒武系过渡层的划分和地层对比有重要意义.

SILICIFIED MICROFOSSILS FROM THE EARLY CAMBRIAN TIANZHUSHAN MEMBER NEAR MIAOHE VILLAGE, ZIGUI, WEST HUBEI, CHINA

Silicified microfossils from the lowermost Cambrian (Tianzhushan Member) at Miaohe village, Zigui County,Hubei Province are described and their biostratigraphic significance is analyzed. All microfossils were observed in thin sec-tions of chert. The assemblage in the lowermost Cambrian contains rich small-sized spiny acritarchs dominated by Micrhystridiumampliatum Wang 1985 (=Micrhystridium lanceolatum L. Yin 1985) associated with Paracymatiosphaera spp., other sphericalforms Leiosphaeridia, Favososphaeridium, Eoaperturilites, and filaments Obruchevella and Megathrix. Most of them weremistakenly described as the components of the Doushantuo assemblage (Sample Hm80-14-2, in L Yin, 1985) and someauthors subsequently quoted the incorrect information.Exactly, the real Doushantuo chert in Miaohe, Zigui contains large and morphologically complex acritarchs, uncompli-cated filamentous and coccoidal microfossils (C. Yin, 1996). The discovery of bonafide Doushantuo and lowermost Cambrianassemblages at Miaohe provides important evidence for the stratigraphic correlation of this section with those Sinian-Cam-brian transition strata in adjacent areas and confirms the distinctness of the Doushantuo biota.