松辽盆地三肇地区白垩系下统泉头组三段上部(杨三组—杨一组)以大套的紫红、红色砂、泥岩沉积为主,在紫红色泥岩中含有较丰富、完整的介形类及其它门类化石。以往认为,这套以红色为基调的地层属河流相沉积。对其中介形类等化石的古生态、埋藏特征及丰度变化的研究表明,该地层的沉积环境应为浅水湖泊环境,而非河流等水上环境。湖相沉积自杨三组就已存在,向上分布范围不断扩大,反映了湖泊水域面积呈现逐渐扩大的趋势。

The upper part of 3rd member of the Early Cretaceous Quantou Formation is primarily composed of purple and red sandstones and mudstones in Sanzhao area, Songliao Basin. Previous studies suggested that the red mudstones, in which abundant and well-preserved ostracods and other fossils have been found, could be considered as fluvial deposits. Based on results of a comprehensive analysis of the abundance variation of ostracod species, their ecologic and taphonomic features, we interpret the mudstones in the upper part of 3rd member of the Quantou Formation was formed in a shallow lacustrine environment. Regional data has further suggested that the lacustrine environment had been existed in the early period and gradually expanding when the oil-generating Yang-3 Formation was deposited.

P618.13 P618.130.2