RAPID: Investigating the Link between Fluvial Flood Events, Remobilization, and Preservation in the Stratigraphic Record along the Northwestern Gulf of Mexico Continental Shelf

RAPID：调查墨西哥湾西北部大陆架地层记录中的河流洪水事件、恢复和保护之间的联系

• 批准号: 1548598
• 负责人: Joseph Carlin
• 金额: $ 2.5万
• 依托单位: CSU Fullerton Auxiliary Services Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1548598&HistoricalAwards=false
• 关键词: RAPID; Investigating; Link; between; Fluvial

This proposal was co-funded by the Sedimentary Geology and and Paleobiology Program (EAR/GEO) and the Marine Geology and Geophysics Program (OCE/GEO)AbstractSediment dispersal in the marine environment from small and moderately sized rivers can often be significantly impacted by episodic events such as large floods. Unlike large rivers with extensive sediment routing systems or large estuaries at their mouths, these smaller rivers have a more direct sediment path to the ocean, thus maintaining a better signal of the flood event. These episodic-event dominated rivers typically reflect climate variability rather than seasonal cycles. This results in the record of past flood events preserved in the marine sedimentary deposit that can give insight into climatic variations over longer time scales. Understanding these past climatic variations regionally will be critical for anticipating future variations due to climate change. Unfortunately, developing strong proxies for river floods using the marine sedimentary record is not a straightforward application due to the complexities of sediment dispersal along continental margins. This project aims to take advantage of recent, near historic floods on the Brazos River, a moderately sized, episodic river draining into the Gulf of Mexico (GOM), to investigate how a flood deposit is ultimately preserved in the continental shelf sediment record. As large floods within this river typically result from El Niño conditions, flood deposits preserved in the sedimentary record will reflect past periods of intense flooding associated with El Niño events in the northwestern GOM. The goal of this study is to develop a high-discharge/El Niño proxy for the northwestern GOM based on this most recent flood event that may be useful for future paleo-climate studies. To accomplish this, PIs plan to collect sediment cores during two sampling cruises along the shelf between the river mouth and the distal depocenter, a feature known as the Texas Mud Blanket (TMB). These cruises will take place at approximately 3 and 6 months following peak discharge to investigate: 1) how the flood deposit changes over this time period; 2) the fraction that may be transported to the TMB during a single event; and 3) the preservation potential of event layers in the TMB. To answer these questions they will delineate the flood layer in the cores by analyzing a variety of sedimentological properties including: physical characteristics, short-lived radioisotopes (e.g. 7Be and 234Th), and elemental composition from XRF core logging. Understanding these depositional characteristics will help to establish an appropriate environmental proxy for such events. Some of the broader impacts from this study include funding an early career scientist, and engaging and training undergraduate and graduate students in geoscience research, many of which will be from traditionally under represented groups.

该提案是由沉积地质和古生物学计划（EAR/GEO）共同资助的，海洋地质与地球物理学计划（OCE/GEO）在海洋环境中的摘要分散体通常会受到小型和中等规模的河流的影响，通常会受到诸如大型地板（例如大型地板）的影响。与大型河流有广泛的沉积物路由系统或嘴巴上的大河口不同，这些较小的河流具有通往海洋的更直接的沉积物路径，从而保持了洪水事件的更好信号。这些事件事件统治的河流通常反映气候变异性，而不是季节性周期。这导致了过去保存在海洋沉积物中的洪水事件的记录，这些事件可以在更长的时间尺度上洞悉杂交变化。了解这些过去的气候变化在区域上对于预期由于气候变化而导致的未来变化至关重要。不幸的是，由于沿连续边缘的沉积物扩散的复杂性，使用海洋沉积记录为河地板开发强大的代理并不是一个直接的应用。该项目的目的是利用近期在墨西哥湾（GOM）的中等规模的情节河（GOM）上的近历史楼层，以调查在连续的架子沉积物记录中最终保存洪水矿床。由于这条河中的大楼层通常是这项研究的目的是基于这一可能对未来的古气候研究有用的最新洪水事件，为西北GOM开发高放电/厄尔尼诺尼诺代理。为此，PIS计划在沿着河口和远端存储者之间的两次采样巡游中收集沉积物芯，该特征被称为德克萨斯泥毯（TMB）。这些巡航将在排放峰值后大约3和6个月进行调查：1）洪水矿床在这段时间内如何变化； 2）在单个事件中可以运送到TMB的分数； 3）TMB中事件层的保存潜力。为了回答这些问题，他们将在分析各种沉积学特性的核心中描绘洪水层，包括：物理特征，短寿命的放射性同位素（例如7BE和234th）以及XRF核心记录的元素组成。了解这些沉积特征将有助于为此类事件建立适当的环境代理。这项研究的一些更广泛的影响包括为早期职业科学家提供资金，以及从事地球科学研究的参与和培训本科生和研究生，其中许多将来自传统上代表的群体。