锡林浩特地区白垩系大磨拐河组的发现及其地质意义

Discovery of Cretaceous Damoguaihe Formation in Xilinhot Area, and Its Paleoclimate Significance

内蒙古锡林浩特市西南覆盖区经横向及垂向调查,发现了一套以砂岩、泥质粉砂岩、泥岩和页岩为主,并夹有煤层的地层,通过岩性组合对比,将其岩石地层单位厘定为大磨拐河组;并在该组二段发现了大量的孢粉化石,其组合面貌特征与我国北方早白垩世早期的分子面貌特征十分接近,其时代应为早白垩世Berriasian-Valanginian期;在该组二段还发现了叶肢介和狼鳍鱼化石,表现出了明显的早白垩世中期的特色,其时代应为早白垩世Barremian期。通过孢粉、叶肢介、鱼化石生物地层确定大磨拐河组的时间跨度为早白垩世Berriasian-Barremian期。

According to vertical geological survey, a series of strata mainly deposited by sandstone, siltstone, mudstone and shale with coal are discovered in the overlay area of Lamayinwusu, Xilinhot, Inner Mongolia. It is recognized as the Damoguaihe Formation by lithological comparison. A large number of sporopollen fossils are discovered in the second section of the core, whose features are similar to those found in Berriasian-Valanginian of Early Cretaceous in North China. The Conchostracans and Lycoptera fossils discovered in the second section of the core indicate the strata was deposited during Barremian of Early Cretaceous. Determined by sporopollen, conchostracans and fish fossils, the age of Damoguaihe Formation is Berriasian-Barremian of Early Cretaceous.