Collaborative research: Quantifying weathering rind formation rates using U-series isotopes along steep gradients of precipitation, bedrock ages, and topography in Guadeloupe

合作研究：利用U系列同位素沿着瓜德罗普岛陡峭的降水梯度、基岩年龄和地形量化风化皮的形成速率

• 批准号: 1251875
• 负责人: Susan Brantley
• 金额: $ 5.22万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-01 至 2017-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1251875&HistoricalAwards=false
• 关键词: Collaborative; research; Quantifying; weathering; rind

The process of mechanical and chemical decomposition of volcanic rocks at the Earth's surface (i.e., weathering) regulates the global carbon cycle, releases nutrients to ecosystems, and sculpts landscapes. Despite its fundamental importance, we still lack effective tools and key observations to quantify the weathering rates of volcanic rocks and to understand how they respond to changes in climate and tectonic regime. During weathering, rock fragments in soils commonly form weathering rinds. These rinds can provide an ideal long-term record to help understand the controls of chemical weathering. Investigators propose to combine a novel U-series isotopic technique with bulk chemical, petrographic, and electron microprobe analyses to quantify formation rates of weathering rinds on the tropical volcanic Basse-Terre Island of French Guadeloupe. By comparing weathering rinds from a single watershed, they will understand the controls on weathering rind formation at the micro-scale through processes including dissolution, formation of new phases, and development of porosity. In addition, the field setting at Basse-Terre Island provides a superb natural laboratory with large environmental variables, allowing them to study rind formation along steep gradients of precipitation, bedrock ages and relief at large watershed scale. The combined analysis of weathering rinds will provide a novel and fundamental method to directly determine chemical weathering rates. This will be of broad interests to scientists worldwide studying the Critical Zone or Earth's surface layer extending from the top of the vegetative canopy to the base of groundwater. For example, such an approach provides a direct means to understand the controls on chemical weathering across different spatial scales. The gained insights will also help to understand how changes in precipitation affect mineral dissolution and reaction surfaces in rinds and soils, and how these processes control river chemistry over long time scales. This project brings together resources and expertise from the U.S., France, and UK. Graduate and undergraduate students at Univ. of Texas at El Paso (UTEP), one of the largest Ph.D.-granting Hispanic Serving Institutes in the U.S., and Dickinson College, an undergraduate-only liberal arts college in Pennsylvania will conduct research at an international Critical Zone research site (Guadeloupe, France) and in research facilities at Pennsylvania State University, Institut de Physique du Globe de Paris, Univ. of Strasbourg, and Univ. of Bristol. This importance is highlighted for UTEP and Dickinson College where the students are rarely exposed to such opportunities at international levels. This project will also support one early career faculty (PI Ma) at UTEP. Educational and outreach activities at UTEP and Dickson College, in collaboration with the NSF funded Pathways and STEP Scholars, as well as Earth Science Day at UTEP, will expose local high school students and general public in the rapidly growing and diverse El Paso region to cutting edge Critical Zone research topics (water, soils, and environments). The project will attract future STEM students who wish to study and solve emerging environmental problems facing the local community.

地球表面火山岩的机械和化学分解过程（即，风化）调节全球碳循环，向生态系统释放营养物质，并塑造景观。尽管它具有根本的重要性，但我们仍然缺乏有效的工具和关键观测来量化火山岩的风化速率，并了解它们如何应对气候和构造体系的变化。在风化过程中，土壤中的岩石碎片通常形成风化皮。这些外皮可以提供一个理想的长期记录，以帮助了解化学风化的控制。研究人员建议将联合收割机一种新的U系列同位素技术与大量化学，岩相学和电子探针分析相结合，以量化法国瓜德罗普热带火山巴斯特尔岛风化皮的形成率。通过比较来自单个流域的风化壳，他们将了解通过溶解、新相形成和孔隙发育等过程在微观尺度上对风化壳形成的控制。此外，巴斯特尔岛的野外环境提供了一个具有大环境变量的一流天然实验室，使他们能够研究沿着大流域尺度的降水梯度、基岩年龄和地形的外皮形成。风化壳的联合分析将为直接测定化学风化速率提供一种新的基础方法。这将对研究从植被冠层顶部延伸到地下水底部的临界区或地球表层的世界各地的科学家产生广泛的兴趣。例如，这种方法提供了一种直接的手段来了解不同空间尺度上的化学风化的控制。所获得的见解也将有助于了解降水的变化如何影响矿物溶解和反应表面的外皮和土壤，以及这些过程如何控制河流化学在很长的时间尺度。该项目汇集了来自美国的资源和专业知识，法国和英国。德克萨斯大学埃尔帕索分校（UTEP）的研究生和本科生，是美国最大的博士学位之一，在美国授予西班牙裔服务机构，迪金森学院是宾夕法尼亚州一所只招收本科生的文科学院，将在一个国际临界区研究基地（法国瓜德罗普）和宾夕法尼亚州立大学、巴黎地球仪物理研究所、斯特拉斯堡大学和布里斯托大学的研究设施进行研究。这一重要性突出了UTEP和迪金森学院的学生很少接触到这样的机会在国际层面。该项目还将支持UTEP的一名早期职业教师（PI Ma）。教育和推广活动在UTEP和迪克森学院，与NSF资助的途径和STEP学者，以及地球科学日在UTEP合作，将暴露当地高中生和公众在快速增长和多样化的埃尔帕索地区的前沿关键区研究课题（水，土壤和环境）。该项目将吸引未来希望研究和解决当地社区面临的新环境问题的STEM学生。