| 湖南衡阳盆地东缘白垩系风成沉积的发现及其古环境意义 |
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| 引用本文： | 黄乐清,黄建中,罗来,王先辉,刘耀荣,梁恩云,马慧英.湖南衡阳盆地东缘白垩系风成沉积的发现及其古环境意义[J].沉积学报,2019,37(4):735-748. |
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| 作者姓名： | 黄乐清 黄建中 罗来 王先辉 刘耀荣 梁恩云 马慧英 |
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| 作者单位： | 湖南省地质调查院,长沙,410116;湖南省地质矿产勘查开发局,长沙,410011 |
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| 基金项目： | 湖南省自然科学基金项目（2017JJ3139）；中国地质调查局项目（DD20160032-09） |
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| 摘 要： | 首次报道了湘中南衡阳盆地东缘上白垩统红花套组中的风成沉积，重新认识了该地区晚白垩世时期的古地理环境。研究区红花套组主要出露一套紫红色块状中-细粒长石石英砂岩、岩屑石英砂岩，普遍见指示风成沙漠环境的巨型板状、楔状交错层理、双向交错层理、平行层理以及典型的风棱石；镜下不含泥质、云母等悬移组分，电镜下可见碟形坑、新月形撞击坑、上翻（平坦）节理片等，综合分析后确认该套砂岩为风成沉积。该套风成砂岩具有重要的古环境意义:风成砂岩的发现，指示该时期为干热气候，沙漠化、盐湖化明显，食物的短缺可能导致衡阳盆地一带恐龙的迁徙；依据沙丘前积纹层倾向特征，恢复了湘中南乃至湖南地区的地表风带特征，为佐证衡阳盆地与其周缘红盆相连通提供一种新的依据。该发现为湖南省的风成沉积领域提供了宝贵的研究材料。
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| 关 键 词： | 风成沉积 古气候 白垩纪 红花套组 衡阳盆地 |
| 收稿时间： | 2018-08-16 |
The Discovery of Cretaceous Eolian Deposits at the Eastern Margin of the Hengyang Basin,Hunan, and Its Paleoenvironmental Significance |
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| Institution: | 1.Hunan Institute of Geology Survey, Changsha 410116, China;2.Bureau of Geology and Mineral Exploration and Development of Hunan Province, Changsha 410011, China |
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| Abstract: | This is the first report of Upper Cretaceous eolian deposits in the Honghuatao Formation at the eastern mar-gin of the Hengyang Basin in central southern Hunan,providing a new understanding of the paleogeographic environ-ment of this area in the Upper Cretaceous. The Honghuatao Formation comprises a set of medium to fine-grained ma-genta feldspar quartz sandstone and lithic quartz sandstone. Large plates,wedge-shaped staggered bedding,bi-direc-tional staggered bedding,parallel bedding and ventifacts are common,all indicating an eolian desert environment. Optical microscope examination shows that suspended components such as mud and mica are absent,and dish-shaped pits,crescent-shaped craters,and upturned (flat) jointed particles are visible under the electron microscope. Comprehensive analysis confirmed that the sandstone is an eolian deposit,which has important paleoenvironmental significance. The discovery indicates that the climate was dry and hot;desertification and saline lakes were obvious, and food shortage might have led to the migration of dinosaurs in the Hengyang Basin. The dip characteristics of the foreset laminae of sand dunes has enabled the characteristics of surface wind belts in Hunan province to be restored, which provides a new basis for supporting the connection between the Hengyang Basin and its surrounding red basins. The discovery provides valuable material for the study of eolian deposition in Hunan province. |
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