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

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。尽管火山岩具有根本重要性，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，并了解它们如何对气候和构造制度的变化作出反应。在风化过程中，土壤中的岩石碎屑通常形成风化皮。这些皮肤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。研究人员建议将一种新的U系列同位素技术与大量化学、岩石学和电子探针分析相结合，以量化法国瓜德罗普岛热带火山Basse-Terre岛上风化皮的形成速度。通过比较单个流域的风化皮，他们将了解风化皮形成在微观尺度上的控制，包括溶解、新相的形成和孔洞的发育。此外，Basse-Terre岛的野外环境提供了一流的自然实验室，具有大量的环境变量，使他们能够研究沿大流域尺度的降水、基岩年龄和地形的陡峭梯度形成的地壳。风化皮的联合分析将为直接确定化学风化速率提供一种新的基本方法。这将对世界各地研究从植被树冠顶部延伸到地下水底部的临界区或地球表层的科学家产生广泛的兴趣。例如，这种方法为理解不同空间尺度上的化学风化控制提供了直接的手段。所获得的见解还将有助于理解降水的变化如何影响土壤和土壤中的矿物溶解和反应面，以及这些过程如何在长时间尺度上控制河流化学。该项目汇集了来自美国、法国和英国的资源和专业知识。大学研究生和本科生。德州大学埃尔帕索分校(UTEP)和宾夕法尼亚州的狄金森学院(Dickinson College)将在一个国际临界区研究站点(法国瓜德罗普)和宾夕法尼亚州立大学巴黎环球物理学院的研究机构进行研究。斯特拉斯堡大学和巴黎大学。布里斯托尔。这一重要性在UTEP和Dickinson学院得到了强调，这些学校的学生很少在国际层面上接触到这样的机会。该项目还将支持UTEP的一名早期职业教师(Pi Ma)。UTEP和Dickson学院与NSF资助的路径和STEP学者以及UTEP的地球科学日合作开展的教育和外联活动，将使快速增长和多样化的埃尔帕索地区的当地高中生和普通公众接触到前沿关键区域研究主题(水、土壤和环境)。该项目将吸引未来的STEM学生，他们希望研究和解决当地社区面临的新的环境问题。

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.