Research Development of Flat-pebble Conglomerate Characteristics and Their Origin in Early Paleozoic North China Platform

Key words: 
• North China Platform /
• continental sea /
• tidal flat /
• bamboo leaf shaped limestone conglomerates /
• limestone conglomerates

Abstract: Limestone conglomerates are widely distributed in Cambrian-Ordovician North China Platform, and only a portion of limestone conglomerates have shape of bamboo leaf viewing from cross section. These limestone conglomerates were mixed with other pebbles. Ancient continental sea was environmental foundation for limestone conglomerates formed. Tidal flat and open marine platform were basic geomorphic units in continental sea, and the main place for limestone conglomerates formed. The ancient plate-motion indicated that North China plate situated in low latitude and has frequent storm wave and hurricane tide, which was the main power for limestone layers broken. In addition, compaction and dewatering also provided power for limestone layers broken. Limestone layers interbedded with mudstone layers or argillaceous limestone was material base for limestone becoming bamboo leaf shaped conglomerates. Limestone conglomerates in North China Platform can be classified and genetically interpreted in terms of color, shapes, the degree of grinding, support structure of limestone conglomerates, filling types. In short, limestone conglomerates in Cambrian-Ordovician North China Platform has many genesis and should be make a difference between various kinds of limestone conglomerates.