蓟县长城系高于庄组内官地亚组的沉积相特征

本文根据对官地亚组岩性、相标志及生物特征分析,认为官地期曾发生二次海侵。第一次海侵形成滨海—浅海相含陆源碎屑碳酸盐岩,自下而上分为陆地边缘碎屑岩、台地潮坪、台地边缘浅滩、开阔台地、台地潮间带等五个沉积相。第二次海侵规模扩大,形成浅海相含燧石碳酸盐岩,从下往上依次为开阔台地、台地斜坡、台地前缘生物礁、台地潮间坪等四个沉积相。

FEATURES OF SEDIMENTARY FACIES OF THE GUANDI SUBFORMATION OF THE GAOYUZHUANG FORMATION OF THE CHANGCHENG SYSTEM IN JIXIAN COUNTY

On the basis of an analysis of the lithology, facies indicators and biological features, it is considered that two marine transgressions took place during this period of time. The first transgression resulted in the formation of littoral-neritic carbonate rocks with terrigenous clastics. From below upward five sedimentary facies may be distinguished, continental margin clastic rocks, platform tidal flat, platform-margin shoal, open platform and platform intertidal zone. The second trasgression was more extensive in scale, producing neritic chert band-bearing carbonate rocks. From below upward four sedimentary facies are recognized: open platform, platform slope, platformfront organic reefs and platform intertidal flat.