老挝桑怒地区中新世含煤盆地沉积相与古地理特征

摘要

基于大量钻井资料分析及数据统计，运用地层学、沉积学和岩相古地理学等理论和研究方法，在老挝桑怒地区新近纪中新世含煤盆地内识别出13种岩石类型、5种沉积相和2种沉积体系。依据单因素分析多因素综合作图法，定量恢复了该地区中新世的岩相古地理格局。当时沉积古地理特征表现为：陡坡带位于盆地西南缘，发育冲积扇—扇三角洲—湖泊沼泽沉积体系；缓坡带位于盆地东北缘，发育辫状河三角洲—湖泊沼泽沉积体系；物源剥蚀区位于盆地西南缘及东北部三叠纪古陆；水流方向由西南部及东北部汇入盆地中心；沉积最大厚度区位于盆地中心区域。%Based on data analysis and statistics of a large number of wells, utilizing theories and methods of stratigraphy, sedimentology and lithofacies palaeogeography, thirteen rock types, five sendi-mentary facies and two depositional systems were recognized in the Neogene Miocene coal-bearing basin in Xam Nua area,Laos.The lithofacies palaeogeographic map was drawn by the single factor analysis and mul-tifactor comprehensive mapping method.The lithofacies palaeogeographic features can be summarized as fol-lows:the steep slope belt was located in southwestern margin of the basin,where the alluvial fan-fan delta-lacustrine system was developed;the gentle slope belt was located in northeastern part of the basin where the braided river delta-lacustrine system was developed;the provenance areas were located in western margin of the basin and the Triassic old land in the northeast of the basin;the water flowed from the southwest and the northeast to the central basin;the largest sedimentary thickness occurred at the central basin.