COLLABORATIVE RESEARCH: Holocene Evolution of the Ganges-Brahmaputra Delta: Implications of Floodplain/Delta Plain Development for Deltaic Models

合作研究：恒河-雅鲁藏布江三角洲的全新世演化：泛滥平原/三角洲平原发展对三角洲模型的影响

• 批准号: 9707067
• 负责人: Mead Allison
• 金额: $ 10.74万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-15 至 2000-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9707067&HistoricalAwards=false
• 关键词: COLLABORATIVE; RESEARCH; Holocene; Evolution; Ganges

9707067 Allison Funds are requested for a two-year collaborative study to examine the Holocene evolution of the Ganges-Brahmaputra delta. The Ganges-Brahmaputra (G-B) river system carries a billion tonnes of sediment annually, yet the fate of this material past the upstream gauging stations, as in most of the world's rivers, is not known. This study will test the hypothesis that at least half of the rivers' sediment load is being sequestered in the floodplain and delta plain, resulting in an evolution and facies architecture significantly different from classic deltaic models. Such magnitude of sediment sequestering, in the Ganges Brahmaputra as well as in other river systems, has important implications for our understanding of the global flux of riverine particulates to the world ocean. The specific objectives of this study are to: 1) Construct a sediment budget for the Holocene floodplain/delta plain: 2) Detail the stratigraphic architecture and history of infilling for the Sylhet, a large tectonic basin located along the previous course of the Brahmaputra: 3) Characterize the nature and magnitude of recent floodplain sedimentation in other portions of the Bengal Basin, including small sub-basins, and bil (wetland) areas; 4) Determine the stratigraphic architecture and magnitude of delta plain sedimentation, focusing on the tidal distributary channels of the Ganges; and 5) Link results from 1-4 above with our previous offshore studies to develop a holistic conceptual model for G-B delta evolution during the Late Holocene. Deep borings (~100 m) and cores will be collected from the floodplain and the delta plain during the dry season in order to construct the sediment budget and to constrain seismic observations. Water-based, high-resolution seismic-reflection studies would be conducted in the Sylhet Basin during the summer monsoon, when the basin is deeply flooded, in order to detail the stratigraphy of the Late Holocene basin fill. Geochronological and sedimentological studies of c ores collected from the floodplain and delta plain will enable us to determine the sediment process rates and stratigraphic architecture of extant sedimentary environments for the G-B system. The completion of the above tasks will enable us to construct a conceptual model of deltaic evolution which will represent an important end-member for deltaic styles, one for which floodplain/delta plain sediment sequestering likely plays a major role. In addition to the aforementioned geological and global implications, the understanding of recent deltaic evolution attained during this study would contribute to a rational strategy for development of one of the most densely populated, low-lying areas of the world

9707067 请求艾里森基金进行一项为期两年的合作研究，以研究恒河-雅鲁藏布江三角洲的全新世演化。 恒河-雅鲁藏布江 (G-B) 河流系统每年携带 10 亿吨沉积物，但与世界上大多数河流一样，这些物质经过上游测量站后的去向尚不清楚。 这项研究将检验这样一个假设，即至少一半的河流沉积物被封存在洪泛区和三角洲平原中，从而导致与经典三角洲模型显着不同的演化和相结构。 雅鲁藏布江恒河以及其他河流系统中如此大规模的沉积物封存，对于我们了解河流颗粒物向世界海洋的全球通量具有重要意义。 本研究的具体目标是： 1) 构建全新世洪泛平原/三角洲平原的沉积物预算： 2) 详细介绍锡尔赫特河（位于雅鲁藏布江前河道的大型构造盆地）的地层结构和充填历史： 3) 描述孟加拉盆地其他部分近期洪泛区沉积的性质和程度，包括小型次盆地和 bil（湿地）区域； 4）确定三角洲平原沉积的地层结构和规模，重点关注恒河潮汐分流河道； 5) 将上述 1-4 的结果与我们之前的海上研究联系起来，以开发全新世晚期 G-B 三角洲演化的整体概念模型。 旱季期间将从洪泛区和三角洲平原收集深钻孔（~100 m）和岩心，以构建沉积物预算并限制地震观测。 夏季季风期间锡尔赫特盆地被深度淹没时，将在锡尔赫特盆地进行基于水的高分辨率地震反射研究，以便详细了解全新世晚期盆地充填物的地层学。 对从洪泛区和三角洲平原收集的岩心进行的年代学和沉积学研究将使我们能够确定 G-B 系统现有沉积环境的沉积过程速率和地层结构。 上述任务的完成将使我们能够构建三角洲演化的概念模型，该模型将代表三角洲样式的重要终端成员，其中洪泛区/三角洲平原沉积物封存可能发挥主要作用。 除了上述地质和全球影响外，在这项研究中获得的对近期三角洲演化的理解将有助于制定世界上人口最稠密、低洼地区之一的合理发展战略。