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

小行星9707067 要求提供资金，进行一项为期两年的合作研究，审查恒河-雅鲁藏布江三角洲全新世的演变情况。 恒河-雅鲁藏布江（G-B）河流系统每年携带10亿吨沉积物，但这些物质经过上游测量站的命运，就像世界上大多数河流一样，尚不清楚。 这项研究将测试的假设，至少有一半的河流的沉积物负荷被隔离在洪泛平原和三角洲平原，导致的演变和相结构显着不同于经典的三角洲模型。 在恒河雅鲁藏布江以及其他河流系统中，这种沉积物螯合的规模对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收支：2）详细描述锡耶特的地层结构和充填历史，锡尔赫特是一个位于雅鲁藏布江上游沿着的大型构造盆地：3）描述孟加拉盆地其他部分（包括小型子盆地）近期洪泛平原沉积的性质和规模，和bil（湿地）地区; 4）确定三角洲平原沉积的地层结构和规模，重点是恒河的潮汐分流河道;和5）将上述1-4的结果与我们以前的近海研究联系起来，以建立晚全新世G-B三角洲演变的整体概念模型。 在旱季，将从洪泛平原和三角洲平原采集深钻（~100米）和岩心，以构建沉积物预算并限制地震观测。 在夏季季风期间，当锡耶特盆地洪水泛滥时，将在该盆地进行基于水的高分辨率地震反射研究，以详细说明晚全新世盆地充填的地层。 对从河漫滩和三角洲平原采集的矿石进行年代学和沉积学研究，将使我们能够确定G-B系统现存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一个概念模型的三角洲演变，这将是一个重要的端员三角洲风格，其中洪泛平原/三角洲平原沉积物封存可能发挥了重要作用。 除了上述地质和全球影响外，在这项研究中对最近三角洲演变的了解将有助于制定合理的战略，开发世界上人口最稠密的低洼地区之一

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