冀北早白垩世地层划分

    HIGH FREQUENCY CYCLIC SEQUENCES AND COMPOSITE SEA LEVEL CHANGE IN THE UPPER MEMBER OF THE ZHANGXIA FORMATION IN FUZHOU,LIAONING PROVINCE

    • 摘要: 从陆相火山—沉积地层中火山岩层与沉积岩层互为楔状(指状)交互关系这一基本特征出发,提出岩石地层单位划分的新思路,并将冀北早白垩世地层划分为西瓜园组、化吉营组及其上覆的青石砬组。化吉营组是在西瓜园组沉积过程中,盆地内叠加了中—中基性及少量酸性—亚碱性火山岩所形成的,故两个组是同期异相的产物,在地层表上表现为并列关系。

       

      Abstract: The record of sedimentary sequences of the Zhangxia Formation in Fuzhou,Liaoning ,shows marked cyclicity,reflectig the features of high frequency cycles.One third order cyclic sequence,4 fourth order cyclic sequences,14 fifth order cyclic sequences and 58 sixth (meter scale)cyclic sequences have been distinguished.The cyclic sequence of each order is composed of the upward shallowing, coarsening and thickening succession of its corresponding cyclic sequence of the smaller order.Its bottom is bounded by the hiatal deepening surface.The fourth ordef cyclic sequence has significance of regional stratigraphic correlation.The sea level at that time has the features of high frequency oscillation and is a cycle of composite sea level change.

       

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