内蒙银根-额济纳旗盆地白垩系中硅化木化石及其沉积环境

内蒙古银根 额济纳旗盆地是我国北方重要的中－新生代陆内含油气盆地，主要出露白垩系冲洪积 河湖相碎屑岩及火山岩夹层。本文描述了在盆地东南部下白垩统巴音戈壁组下段（1号）和苏红图组二段底部（2号）发现的上、下两处原始埋藏的硅化木化石，并探讨了早白垩世时期盆地沉积时的气候环境。两处化石均保存完好，表面结构较为完整。巴音戈壁组上部和苏红图组下部泥岩段孢粉分析结果显示地层时代为早白垩世中晚期。同时，孢粉植物群揭示该时期银根 额济纳旗盆地气候环境温暖湿润，植被茂盛。根据化石保存特征和产出位置的地层岩性，初步推测1号硅化木化石点系冲洪积物快速堆积所致，2号硅化木化石点系火山喷发物瞬间埋藏所致，其埋藏时代大致为早白垩世晚期。

Early Cretaceous petrified woods and sedimentary environment from Yingen-Ejinaqi Basin, Inner Mongolia

Yingen Ejinaqi Basin, a Mesozoic Cenozoic intermountain petroliferous basin in Inner Mongolia, northern China, is largely filled by the Cretaceous alluvial fluvial lacustrine clastic sediments interbedded with volcanic layers. Two sites of well preserved silicied woods were discovered in the Lower Cretaceous Bayingebi Formation and Suhongtu Formation in the southeastern Basin. In this paper, we firstly described the taphonomic characteristics and morphological structures of silicied woods and then discussed the climatic environment when they buried based on the palynologic datas. In addition, palynological samples were collected from the upper Bayingebi Formtion and lower Suhongtu Formtion. The palynological study suggests a late Early Cretaceous age, and also reflects a wet and warm climate in this area. According to the lithological characters, the first locality of the fossil woods was rapidly buried by intermittent floods, debris flows deposits. And the second ones was suddenly covered by pyroclastic deposits which possibly occurred at the late Early Cretaceous period on the basis of published dates.