山西永济白草坪组具刺疑源类的发现及其地质意义

该文着重报道了山西永济白草坪组(一般认为系中元古界上部相当于蓟县系的层位),以具刺疑源类为主的微化石群,计有4类6属15种,其中包括1新属,4新种,1新组合,1亲近种,2未定种,新属是具细网状纹饰的复杂具刺疑源类Shuiyousphaeridium Yan gen.nov.,4新种是Shuiyousphaeridium membraniferum Yan sp.nov.,Dictyosphaera incrassate Yan sp.nov.,Foliomorpha stipuliferaYan sp.nov.,Manicosiphoninema shuiyouense Yan sp.nov.。本微化石群以球形疑源类为主体,以具刺疑源类的大量发育为特征,并伴生有推测是绿藻和褐藻的化石,其组合面貌与蓟县上前寒武系各组皆有明显区别,具有更高的进化程度,从生物地层标志推测白草坪组所在的汝阳群应归入震旦系。白草坪组具刺疑源类可能是横裂甲藻的原始分子,它在地层对比和藻类进化方面皆具有重要意义。

DISCOVERY OF ACANTHOMORPHIC ACRITARCHS FROM THE BAICAOPING FORMATION IN YONGJI,SHANXI AND ITS GEOLOGICAL SIGNIFICANCE

The Baicaoping Formation in Yongji, Shanxi, as one of the lithologic units in the upperPrecambrian Ruyang Group, is composed of siltstone and shale of near--shore facies. In the blackishgrey Shales have been discovered spinose and sphaeroid acritarchs as well as microfossil remains ofsupposed green and brown algae. This microfossil assemlage comprises 6 genera and 15 species,including 1 new genus (Shuiyousphaeridium Yan), 4 new species (Shuiyousphaeridium membraniferumYan, Dictyosphaera incrassata Yan, Foliomorpha stipulifera Yan, Manicosiphoninema shuiyouense Yan) and1 new combination (Shuiyousphaeridium macroreticulatum (Du) Yan). The most common elements of the spinose acritarchs are vesicles of Shuiyousphaeridiummacroreticulatum(Du) Yan gen et comb. nov., which are large in size, with numerous branchesfurcated and enveloped by peteinos processes. Due to the appearance of complicated spinose acritarchs,it may be inferred that the Baicaoping Formation belongs to the upper Proterozoic Sinian system. Thecomplicated spinose acritarchs may be the primitive forms of dinoflagellate. They are not only ofbiostratigraphical value, but also important for understunding the evolution of Precambrian algae.