摘要： 豫西登封寒武系第三统灰岩中的鲕粒自下而上个体直径与鲕核逐渐变小、形态变得更加浑圆、鲕粒间胶结程度更高,反映了从深水不稳定鲕粒灰岩到浅水高速建造鲕粒滩的演变过程。研究区鲕粒灰岩发育可以分为3个阶段:(1)台地深斜坡鲕粒灰岩建造阶段(A段),主要发育放射鲕及同心—放射鲕,鲕粒形态多样、粒径大,粒间多为灰泥充填;(2)滩前缓斜坡鲕粒灰岩建造阶段(B段),主要发育同心—放射鲕、同心鲕,鲕粒含量极不稳定,粒径差异大,粒间由微亮晶及亮晶方解石胶结;(3)台内鲕粒滩高速建造阶段(C段), 主要发育白云化的同心鲕和微晶鲕,鲕粒含量极高、粒径极小,鲕核也很小,粒间由亮晶方解石胶结。由A段到C段,相对水深逐渐变浅,成鲕环境变得成熟而稳定,鲕粒沉积规模逐渐扩大。

关键词: 鲕粒, 鲕粒灰岩, 寒武系, 第三统, 张夏组, 豫西

Abstract: The ooids have the trends to be much smaller in individual and core diameters, much rounder in shape and higher sparry cementation among ooids from bottom to top in the oolitic limestones of the Cambrian Series 3 in Dengfeng area, western Henan Province. These characteristics display the evolution from unstable oolitic limestones of deep continental shelf to much shallower high construction bank shoals. Three stages of oolitic limestones can be distinguished as follow.(1)The oolitic limestones occurred in deep platform slope are dominated by radial and tangential-radial ooids. The ooids have the big size and the higher diversity in their shapes. The filling arounding them is mostly consisted of mud.(2)The oolitic limestones occurred in oolitic shoal front of gentle platform slope contain tangential-radial and tangential ooids and have the variable oolitic content and size. The porosity among ooids occupied by microsparry and sparry calcites.(3)The high construction oolitic shoals of the platform margins are characterized by dolomitic tangential and micritic ooids and have the much higher oolitic content and much smaller size. The porosity among ooids occupied by sparry calcite. The relative water depth become much shallower, the construction environment of oolitic shoals become much perfect and stable, the thickness and distribution of oolitic shoals gradually expand the scales from Member A to Member

Key words: C.ooids, oolitic limestone, Cambrian, Series 3, Zhangxia Formation, western Henan Province

中图分类号: 

• P588.24+5A