越南下龙湾石炭纪巴什基尔期Pseudostaffella■类动物群

THE BASHKIRIAN (CARBONIFEROUS) PSEUDOSTAFFELLA FUSULINID FAUNA FROM THE HALONG BAY,NE VIETNAM

作者报道了越南下龙湾地区的一个■类动物群,该动物群产于下龙湾吉婆岛东的一个小岛的石灰岩地层中,其中以Pseudostaffella为主,Eostaffella次之。文中描述7个种,即:Pseudostaffella composita,P.sub-quadrata vozhgalica,P.antiqua,P.antiqua grandis,Eostaffella post mosquensis,E.mosquensis及E.galinae,其中以Pseudostaffellacomposita最为丰富,可称之为Pseudostaffella动物群。该动物群层位高于下龙湾地区Bacson组中的Millerella-Eostaffella带,相当于宾夕法尼亚系巴什基尔阶上部,中国贵州盘县滑石板阶层型剖面的Pseudostaffellacomposita-P.paracompressa带,俄罗斯下巴什基尔阶Prikamsky层的Pseudostaffella prae-gorskyi-Profusulinella staffellaeformis带的一部分,以及北美宾夕法尼亚系莫洛阶Millerella带与阿托克阶Profusulinella组合带之间的Pseudostaffella和Eostaffella的化石层。下龙湾Pseudostaffella■类动物群的发现具有重要的地层学和古生物学意义,它对于进一步认识该地区地质演化及古生物地理变迁均有裨益。

This paper reports a Carboniferous fusulinid fauna discovered from marine carbonate rocks at an islet to the east of the Catba Island in the Halong Bay, NE Vietnam. The fauna is represented by Pseudostaffella and Eostaffella with the former as the dominant taxon. Seven species are described and illustrated in this paper. They are Pseudostaffella composita, P. subquadrata volzhgalica, P. antiqua, P. antiqua grandis, Eostaffella postmosquensis, E. mosquensis, E. ganelina, among which Pseudostaffella composita and P. subquadrata vozhgalica are most abundant and the fauna is named as the Pseudostaffella fauna. Stratigraphically this fauna can be assigned to and is higher than the Millerella-Eostaffella Zone of the Bacson Formation in the Halong Bay area. It corresponds to the upper part of the Bashkirian of the Pennsylvanian and to the Pseudostaffella composita-P. paracompressa Zone of the Huashibanian, Panxian, Guizhou, S. China. It also corresponds in part to the Pseudostaffella praegorski-Profusulinella staffellaeformis Zone of the Prikamsky Bed, Bashkirian, Russia and the Pennsylvanian Pseudostaffella and Eoschubertella-bearing strata between the Morrowanian Millerella Zone and Atokenian Profusulinella Assemblage Zone of the North America. The discovery of the Pseudostaffella fauna from the Halong Bay is of significance palaeotologically and stratigraphically. It helps a better undersdanding of geological and palaeobiogeographical evolution of this region.