CAREER: Investigating the source, transport and deposition of economically important metals in the lower continental crust

金属是现代社会的重要组成部分。除了回收，金属还可以从矿床中回收，例如岩浆硫化物系统，这些矿床通常形成于靠近地表的地方，因此相对容易获得镍和铜等金属。由于矿床是不可再生的，我们必须为每一个枯竭的资源找到（至少）一个新的存款，以保证未来稳定的金属供应。目前，矿产勘探工作主要集中在地壳上部，因为这种方法在过去世纪一直行之有效。然而，最近新发现的矿藏减少，这意味着地表附近的矿藏大多已被发现，因此，有必要在地球更深处开辟搜索空间，以保证稳定的金属供应。本项目将通过调查意大利Ivrea-Verbano区一系列岩浆交代硫化物矿床的形成来解决这一问题。这些矿床形成于地壳深部，经构造抬升至可开采水平。尽管这些矿床以前曾被开采过镍和铜，但令人惊讶的是，人们对它们（以及其他地方的类似矿床）最初是如何形成的知之甚少。该项目将利用Ivrea-Verbano区的矿床，更好地限制这些矿床优先形成的方式和地点，特别关注地幔交代作用在地壳深部成矿中的作用。这些发现将为将此类矿床纳入未来勘探模型迈出重要一步。该研究将与教育部分相结合，将达到K-12，本科生和研究生。一个与“带路项目”合作的高中外展计划将使用该项目的例子来突出K-12学生最初可能不知道的地球科学职业道路，特别是在密苏里州农村。PI还将把拟议研究的各个方面纳入本科生的暑期培训计划，以帮助学生为学士学位后的地球科学职业做好准备。此外，两名研究生将积极参与研究部分。Ivrea-Verbano带是一个保存完好的亚大陆岩石圈地幔和下陆壳的剖面，它近垂直地出露，因此可以对深部岩石圈质量转移进行全面研究。以往对伊夫雷亚-韦尔巴诺带的研究对我们了解下大陆岩石圈有重要贡献。然而，关注含金属含水熔体/流体的来源及其在金属运输和局部沉积中的作用（即，矿石储量稀少。为了解决这一知识缺口，本项目将调查Ivrea-Verbano带中代表不同程度的交代作用和硫化物矿化的不同地点：（1）强烈交代/高度矿化的管道，（2）未交代/中度矿化的岩床/侵入体，以及（3）强烈交代/硫化物贫乏的地幔橄榄岩。实地研究将与岩相学观察、大块岩石、矿物和流体包裹体分析、同位素（Cu、Sm-Nd）和年代学研究相结合。拟议的研究将为以下方面提供新的见解：（1）在岩石圈深部产生、运输和浓缩流体和金属的物理和化学过程;（2）这种过程的空间和时间尺度。PI正在积极招募K-12教师，本科生和研究生参与这个项目。K-12外展计划的目标是提高对地球科学学科的认识，并鼓励学生考虑地球科学或其他STEM职业道路。本科生和研究生的项目将被单独定制，为每个学生在学术界，联邦/州机构或私营部门选择的职业道路做好准备。该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Metals are critical components of modern society. Aside from recycling, metals are recovered from ore deposits such as magmatic sulfide systems that often formed close to the surface and thus provide relatively easy access to metals like nickel and copper. Because ore deposits are non-renewable, we must find (at least) one new deposit for each exhausted resource to guarantee a steady metal supply in the future. Currently, mineral exploration efforts focus mostly on the upper crust because this approach has worked well over the past century. However, a recent decline in new discoveries implies that most of the deposits near the surface have already been found. Consequently, the opening of search space deeper in the Earth is necessary to guarantee a steady metal supply. This project will address this issue by investigating the formation of a series of variably metasomatized magmatic sulfide deposits in the Ivrea-Verbano Zone in Italy. These deposits formed in the deep crust and were tectonically uplifted to mineable levels. Although the deposits were previously mined for nickel and copper, surprisingly little is known about how they (and similar deposits elsewhere) originally formed. This project will use the deposits in the Ivrea-Verbano Zone to better constrain how and where such deposits preferentially form, particularly focusing on the role of mantle metasomatism in deep crustal ore formation. The findings will provide an important step toward including such deposits in future exploration models. The research will be integrated with an educational component that will reach K-12, undergraduate and graduate students. A high school outreach program in collaboration with Project Lead The Way will use examples from this project to highlight geoscience career paths that K-12 students may initially not be aware of, particularly in rural Missouri. The PI will also incorporate aspects of the proposed research into a summer training program for undergraduate students to help students prepare for a post-baccalaureate geoscience career. Furthermore, two graduate students will be actively involved in the research component. The Ivrea-Verbano Zone is a well-preserved cross section of the subcontinental lithospheric mantle and lower continental crust that outcrops subvertically and therefore allows for comprehensive studies of deep lithospheric mass transfer. Previous studies on the Ivrea-Verbano Zone have significantly contributed to our understanding of the lower continental lithosphere. However, research that focuses on the source of metalliferous hydrous melts/fluids, and their role in the transport and local deposition of metals (i.e., ore deposits) is rare. To address this knowledge gap, this project will investigate different localities in the Ivrea-Verbano Zone that represent variable degrees of metasomatism and sulfide mineralization: (1) strongly metasomatized / highly mineralized pipes, (2) un-metasomatized / moderately mineralized sills/intrusions, and (3) a strongly metasomatized / sulfide-poor mantle peridotite. Field studies will be integrated with petrographic observations, bulk rock, mineral and fluid inclusion analyses, isotopic (Cu, Sm-Nd) and geochronological studies. The proposed research will provide new insight into (1) the physical and chemical processes that produce, transport and concentrate fluids and metals in the deep lithosphere; and (2) the spatial and temporal scales of such processes. The PI is actively recruiting K-12 teachers, undergraduate and graduate students to be involved in this project. The goal of the K-12 outreach program is to raise awareness for geoscience disciplines and to encourage students to consider geoscience or other STEM career paths. Undergraduate and graduate student projects will be individually tailored to prepare each student for a career path of their choosing in academia, federal/state agencies, or the private sector.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.