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松辽盆地上白垩统青山口组发育含大量介形虫化石的介形虫层,介形虫层的单层厚约5～200cm。介形虫层具有低伽马、高电阻、低声波等测井响应特征。以测井资料识别介形虫层为基础,研究了介形虫层在平面上不同相带及其在纵向高频层序格架下的分布规律,探讨了介形虫群集性死亡的原因。介形虫层平面上主要分布在大庆、龙虎泡—红岗阶地、黑帝庙等环坳带,盆地东部相对不太发育,滨浅湖是介形虫生存的有利环境;纵向上主要分布在青一段上部及青二段。高频层序旋回控制了介形虫的繁殖与死亡,介形虫群集性死亡事件主要发生在基准面下降期间。介形虫的群集性死亡与湖泊面积扩大无关,更与海侵事件无关。基准面下降造成水体变浅、矿化度增高以及砂岩进入滨浅湖可能是导致介形虫群集性死亡的直接原因。
The Cretaceous Qingshankou Formation in the Songliao Basin is characterized by a large number of ostracods containing a large number of ostracods. The thickness of the ostracode is about 5-200 cm. Ostracoda has low gamma, high resistance, low acoustic logging response characteristics. Based on the log data recognition of ostracoda, the distribution of ostracods in different facies and their distribution under vertical high-frequency sequence framework was studied, and the reason for the cluster death was discussed. Ostracoda layers are mainly distributed in the Daqing, Longhupao-Honggang terraces, Hei Di Temple ring and other reclaimed areas. The eastern part of the basin is relatively underdeveloped, and the shallow and shallow lakes are favorable environments for the survival of the ostracods. In the longitudinal direction, Green section of the upper and green section. The high frequency sequence cyclotron control the propagation and death of ostracods, and the ostracodectomial death occurred mainly during the fall of the datum. The incidence of ostracod clusters was unrelated to the enlargement of lakes and more to transgression. The lowering of the datum surface leads to the shallow water body, the higher salinity, and the sandstone entering the shallow lake, which may be the direct cause of the ostracod cluster death.