根据1∶5万区域地质调查,大兴安岭北端上黑龙江盆地内的原中侏罗统二十二站组的时代被重新厘定为中、晚侏罗世Bajocian─Tithonian期并改称为二十二站群。根据岩性特征和化石组合,将其进一步划分为两个组:下部称大西尔根气河组,其下部岩性以砂岩为主,上部以泥质粉砂岩─砂岩为主,含中侏罗世至晚侏罗世早期的双壳类动物群化石,可划分为Sibireconcha─Cuneopsis,Margaritifera─Unio,Fergannoconcha3个生物组合;上部称马林组,主要由粉砂岩组成,夹有少量砾岩和粉砂质灰岩,含晚侏罗世中晚期的介形类动物群化石,可称为Eoparacypris─Rhinocypris─Yanshanina组合。 According to 1: 50000 regional geological survey, the age of the Middle Jurassic Twenty-two Stations in the Heilongjiang Basin on the northern tip of the Daxinganling Mountains was re-determined as the middle-late Jurassic Bajocian-Thononian period and renamed as twenty-two stations . Based on the lithological characteristics and fossil assemblages, it is further divided into two groups: the lower part of the Greater Seergen gas group, the lower part of which is dominated by sandstone and the upper part is dominated by argillaceous siltstone-sandstone with middle Jurassic Fossils of Bivalve fauna can be divided into three biological assemblages of Sibireconcha ─ Cuneopsis, Margaritifera ─ Enio, Fergannoconcha; the upper part of the Marin group, composed mainly of siltstone with a small amount of conglomerate and powder The sandy limestone, with the fossil from the late Late Jurassic ostracod, may be called the Eoparacypris-Rhinocypris-Yanshanina combination.