冀北承德盆地杏石口组沉积特征及时代讨论

河北省杏石口组次层型的武厂剖面存在下部层位发育不齐全、构造破坏严重且有后期脉岩侵入等诸多不利因素。为此,该文对承德县上谷娘娘庙杏石口组地层剖面进行了重新观测,将其进一步细分为两个岩性段: 一段以粗碎屑沉积为主,岩性主要为砾岩夹少量砂岩透镜体; 二段主体为一套细碎屑沉积,岩性为砂岩、粉砂岩、粉砂质泥岩(局部发育1~2层煤线)。在系统总结古生物特征、孢粉组合及同位素年龄数据等资料基础上,认为杏石口组的沉积时限为晚三叠世。

Sedimentary Characteristics and Stratigraphic Age of Xingshikou Formation in Chengde Basin of Northern Hebei

The Wuchang section is used as a hypostratotype for the Xingshikou Formation in Hebei province within the limits of discontinuous stratigraphic sequence, complicated structure, and dyke intrusion of later stage. To reevaluate the Xingshifou Formation, the Niangniangmiao section which can be divided into two lithologic members in Shanggu town of Chengde County is surveyed. The lower member is coarse clastic sediment with gravel and interbedded sandstone lens, and the upper member is fine clastic sediment with sandstone, siltstone, silty mudstone and occasional one or two layer coal seams. The stratigraphic age of the Xingshikou Formation might be formed in Late Triassic according to paleontology assemblages, pollen assemblages and isotopic data.