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NSF GEO-NERC: Collaborative Research: Impact of the Plio-Pleistocene Transition on Provenance and Sediment Routing from the Himalaya to the Deep-Sea Bengal Fan

NSF GEO-NERC：合作研究：上里奥-更新世转变对从喜马拉雅山到深海孟加拉扇的物源和沉积物路径的影响

基本信息

批准号：
2026870
负责人：
Devon Orme
金额：
$ 21.73万
依托单位：
Montana State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-08-15 至 2024-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2026870&HistoricalAwards=false
关键词：
NSF GEO NERC Collaborative Research

项目摘要

The Himalayas represent the largest mountain chain on Earth, and reside mostly in Nepal, India, Pakistan and China. The Himalayas began rising many millions of years ago when India collided with Asia, which changed Earth’s climate, altered ocean circulation and chemistry, and impacted the course of biological evolution. Erosion of the Himalayas resulted in deposition of the largest pile of sediment on the planet in the Bay of Bengal, the deep-sea Bengal Fan. Within this sediment record lies the history of the Himalayas – the now eroded Mt. Everests of the past, buried under sediment of the continental shelf and the deepest parts of the Indian Ocean. In 2015, a multi-national expedition on the JOIDES Resolution, a specially designed scientific drilling ship, recovered ~1.5 miles of sediment cores that contains this record. New research will use these sediments to trace the history of Himalayan erosion and how two of the world’s largest rivers, the Ganges and Brahmaputra, delivered it to the Bay of Bengal over the last 3-5 million years. Giant mountain ranges like the Himalayas are a rarity through geologic history, but without the Himalayas there are no drenching Asian monsoons, no fertile floodplains or aquifers, no ancient Indus Civilization, and no Mt. Everests in that part of the world. The results of this research will therefore tell us about climate change, landscape evolution, and how one of the world’s most densely populated areas came to be as seen today. Understanding the past in this way can help us better understand the future for the 10% of the world’s population that lives under the influence of this incredible geographic feature. This project also supports international collaboration between scientists and students from several universities in the U.S., the U.K. and several Asian countries where field work will be conducted.The Himalaya-sourced Ganges-Brahmaputra river system and the deep-sea Bengal Fan represent Earth’s largest source-to-sink sediment-dispersal system. IODP Expedition 354 drilled a 7-site transect in the middle Bengal Fan, almost 1000 miles from the modern Ganges-Brahmaputra delta shoreline, to expand the record of erosion and sediment routing from the Himalaya to the deep sea. Previous research examined detrital-zircon (DZ) U-Pb data from sandy turbidites in IODP 354 core to summarize Miocene to middle Pleistocene patterns of sediment routing: this research identified major changes in specific DZ U-Pb age populations that correspond to the Plio-Pleistocene transition, and indicate major changes in provenance due to environmental forcing. New research will build on earlier results and examine climatic and tectonic processes that drove this provenance change. This research will be grounded on analyses of 25 new samples of Plio-Pleistocene sand from IODP 354 core, which represent sand transport to the Bengal Fan during glacial periods when sea level was low, as well as 60 new river sand samples from the modern Ganges-Brahmaputra drainage that will be used to establish patterns characteristic of the Holocene interglacial monsoon-dominated climate. Detrital zircons and rutiles recovered from the sand fraction in these samples will be used as the primary signal carrier and will be analyzed for U-Pb geochronology, with zircons examined for (U-Th)/He thermochronology and Hafnium isotopes as well. These samples and methods will fingerprint contributions from the main tectonostratigraphic units of the Himalaya to the Bengal Fan in glacial vs. interglacial periods and show how Himalayan erosion and sediment routing to the deep sea changes over time. The dataset generated will serve the community as a baseline for decades, and will be leveraged as a tool for public outreach at professional meetings and workshops that emphasize source-to-sink concepts and how the Himalaya to Bengal fan system responds to and records climate change and tectonic activity.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

喜马拉雅山脉代表着地球上最大的山脉，主要居住在尼泊尔、印度、巴基斯坦和中国。喜马拉雅山脉在数百万年前印度与亚洲相撞时开始上升，这改变了地球的气候，改变了海洋循环和化学物质，并影响了生物进化的进程。喜马拉雅山脉的侵蚀导致了地球上最大的沉积物堆积在孟加拉湾，即深海孟加拉扇。在这个沉积物记录中隐藏着喜马拉雅山脉的历史--现在被侵蚀的山峰。过去的珠穆朗玛峰，埋在大陆架和印度洋最深部分的沉积物下。2015年，在一艘专门设计的科学钻探船JOIDES Resolve上进行的一次跨国探险，发现了含有这一记录的约1.5英里的沉积物岩心。新的研究将利用这些沉积物来追溯喜马拉雅山脉侵蚀的历史，以及世界上最大的两条河流--恒河和雅鲁藏布江--是如何在过去300-500万年间将其输送到孟加拉湾的。像喜马拉雅山脉这样的巨型山脉在地质史上是罕见的，但没有喜马拉雅山脉就没有湿润的亚洲季风，没有肥沃的洪泛平原或含水层，就没有古老的印度河文明，也没有山脉。世界上那个地方的珠穆朗玛峰。因此，这项研究的结果将告诉我们气候变化、景观演变，以及世界上人口最稠密的地区之一是如何变成今天所见的。以这种方式了解过去，可以帮助我们更好地了解生活在这一令人难以置信的地理特征影响下的10%世界人口的未来。该项目还支持来自美国、英国和几个亚洲国家几所大学的科学家和学生之间的国际合作，这些国家将进行实地研究。发源于喜马拉雅的恒河-雅鲁藏布江水系和深海孟加拉扇是地球上最大的从源到沉的沉积物扩散系统。IODP探险354在距离现代恒河-雅鲁藏布江三角洲海岸线近1000英里的孟加拉扇中部钻探了一条7个地点的横断面，以扩大从喜马拉雅到深海的侵蚀和泥沙输送记录。以前的研究分析了IODP 354岩心砂质浊积岩的碎屑-锆石(DZ)U-Pb数据，以总结中新世至中更新世的沉积路径模式：这项研究确定了与更新世-更新世过渡相对应的特定DZ U-Pb年龄组的主要变化，并表明由于环境强迫，物源发生了重大变化。新的研究将建立在早期结果的基础上，并检查推动来源变化的气候和构造过程。这项研究将基于对来自IODP 354岩心的25个新的上更新世沙子样品的分析，这些样品代表了在海平面低的冰川时期向孟加拉扇输送的沙子，以及60个新的来自现代恒河-雅鲁藏布江流域的河沙样品，这些样品将被用来建立以全新世间冰期季风气候为特征的模式。从这些样品的砂粒中回收的碎屑锆石和金红石将作为主要的信号载体，并将进行U-Pb年代学分析，同时还将对锆石进行(U-Th)/He热年代学和Hafn同位素研究。这些样品和方法将对喜马拉雅主要构造地层单元在冰期和间冰期对孟加拉扇的贡献进行指纹识别，并显示喜马拉雅侵蚀和向深海输送沉积物的变化。生成的数据集将作为数十年来社区的基线，并将在专业会议和研讨会上用作公共宣传的工具，强调从源头到汇点的概念，以及喜马拉雅到孟加拉的扇形系统如何响应和记录气候变化和构造活动。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。