湖北秭归庙河早寒武世水井沱组燧石层中的微化石

MICROFOSSILS FROM THE CHERTS OF THE LOWER CAMBRIAN SHUIJINGTUO FORMATION AT MIAOHE, ZIGUI, HUBEI PROVINCE

本文首次报道了湖北秭归庙河早寒武世水井沱组底部,燧石层岩石薄片中发现的徽化石9个属、9个种和3个未定种(包括1个新种)。依据这些化石材料,论证了本区水井沱组底部这一化石层位可能相当梅树村阶小壳化石第2—3组合带。为解决本区震旦系—寒武系界线地层的对比,提供了极为重要的古生物依据。

The microfossils described and illustrated in this paper were discovered in the black chert of the lowest part of the lower Cambrian Suijingtuo Formation at Miaohe village, Zigui, Hubei Province. All of the microfossils were observed in the thin-sections of sample 1—891020, which yield 9 genera, 9 species and 3 ndeterminate species(including a new species). Among them Micrltystridium sp. and Micrhystridium lanceolatum Yin are very common and Paracymatiophaera regularis Wang, Paracymatiosphaera irregularis Wang, Paracymatiosphaera annularis Wand and Skiagia multispinosa sp. nov. are relatively rare. A conodont-like fossil Kaiyangites multispinatus is associated with the acritarch microfossils. The fossil assemblage provides an important evidence for the definition of the Sinian-Cambrian boundary in this area, and for the correlation with the Sinian-Cambrian boundary strata of the adjacent areas. Description of the new species: Genus Skiagia Downie, 1982 Skiagia multispinosa sp. nov. (P1. 1, figs. 5—7) Vesicle spherical or slightly ellipsoidal, diameter 17—25μm (averagely 20μm, n=25), surface psilate or weakly coarse, with numerous processes which are widened distally to form funnel-shaped terminations, processes 4—9μm long(23—36% of vesicle diameter). Comparison: Horizon and locality: Shuijingtuo Formation, Lower Cambrian, at Miaohe village, Zigui, Hubei Province.