关键词: 华北, 寒武系第三统, 鲕粒灰岩, 环境意义

Abstract: The study area, geographically including Beijing, Tianjin, Shanxi and Hebei Provinces, is the main part of the North China Plate. Based on the study of outcrop and thin section observation, the distribution pattern of oolitic limestone and its ooid characteristics are presented. Olitic limestones were widely distributed in the area during the Third Series of Cambrian. Generally, the oolitic limestone elevates in strata gradually from east to west, which indicates that the oolitic limestone is diachronous. Huge oolitic shoals distribute along a western ward bulging belt from north to south, and mainly are composed of concentric ooids. In west of the belt, the thickness of the oolitic limestone decreases rapidly, and the oolitic limestone mainly is composed of radial ooids. In east of the belt, the oolitic limestone thins gradually, with majority grains of concentric ooids. The marine transgression during the Third Epoch of Cambrian took place from east to west on the North China Plate. In this background, the inner ramp ooid shoals developed in the central belt of the study area, with open sea in the east and shoal back tidal flat in the west.

Key words: North China, the Third Series of Cambrian, oolitic limestone, sedimentary environment