周口盆地早日垩世地层的发现

周口盆地位于淮河流域上游,横跨豫、皖两省,广大地区均被第四系所覆盖。近几年来,随着石油普查和勘探工作的进展,盆地中第四系以下地层已有许多新的揭露和发现。1983年在周口盆地沈丘拗陷的钻探工作中,南2井和周参10井相继揭露了一套黑灰色地层,主要岩性为深灰色、黑灰色泥岩与浅灰色、灰色粉—细砂岩互层夹多层碳质页岩和煤线,厚约606米。在其中发现了丰富的孢粉化石,经笔者研究和鉴定,发现有47属,74种,其中有3个新种。该孢粉化石组合指示这组地层地质时代为早白垩世。周口盆地早白垩世黑灰色地层的发现,为石油和天然气的勘探开拓了新的领域。 

DISCOVERY OF THE LOWER CRETACEOUS STRATA IN ZHOUKOU BASIN,EASTERN HENAN

The materials dealt with the present paper are obtained from the drilling cores of the Shengqiu Formation in Zhoukou Basin.This formation is composed of a series of grey, dark grey, black claystones and light grey, fine to medium grained sandstones, intercalated with black carbonaceous shales and bands of coal, containing abundant sporo-pollen. This sporo-pollen assemblage is characterized by the predominance of gymnospermous pollen (83-61%), relatively abundant pteridophytic spores (9-17%) and few grains of angiospermous pollen. The gymnospcrmous pollens mainly consist of classopollis (60-84%). In addition, it contains some disacoate pollen grains, Cycadopites,Araucariacites, Psophosphaera,etc.. The pteridophytic spores arc characterized by the dominance of Lygodiaceae(5-12%), which includes Cicatricosisporites, Schi-zaeoisporites, Lygodiumsporites, Concavissimisporites, Klukisporites, Ver-rucosisporitcs, Contignisporites, etc.. Jugella of presumed angiospermous are very rare. This sporo-pollen assemblage is similar to those from South China named Classopollis-Schizaeoisporites microflora (Li wenben, 1980), therefore, the Shenqiu Formation is probably Early Cretaceous in age (Barremian).It is suggested that the climate of Zhoukou Basin should be of dry tropical-subtropical type at that time.