Collaborative Research: A New Approach to Detrital Provenance Determination: Application of Laser-Induced Breakdown Spectroscopy (LIBS) to the Tourmaline Supergroup Minerals

了解地球的地质历史有助于洞察塑造地球的过程和经济资源的分布。然而，古代地质事件可能很难破译，因为它们的物理存在可能会因侵蚀而消失。幸运的是，关于风化和侵蚀之前存在的岩石的类型和年龄(即其来源)的信息被编码在沉积物和沉积岩中保存的一些矿物中。电气石就是这样一种矿物。它是地质信息的关键储存库，因为它包含了广泛的化学元素，反映了它形成的岩石环境--也就是说，它编码了岩石的化学签名，类似于指纹。电气石也是一种耐化学和机械性能的矿物，当它从形成电气石的岩石中风化出来时，它可以变成沙粒，并入沉积物(和岩石)中。电气石颗粒一旦包含了其原始的化学特征，就会将该特征存储数百万年或数十亿年。这项工作使用了一种协同方法来破译以前的地质事件，它们在沉积物和岩石中的记录，方法是将使用新技术的激光诱导击穿光谱(LIBS)对矿物电气石的化学分析与现有的电子显微探针分析(EMP)相结合。两者都能产生原位化学指纹：LIBS具有优势，因为它收集所有元素及其络合物的信号，包括轻元素，并提供元素的相对组成；而电磁脉冲是一种成熟的分析技术，用于高精度和准确的微米级大多数元素(轻元素H、Li除外)的化学数据。这项工作的一个目标是利用这些互补技术，根据大量已知出处的电气石样本，开发确定出处的可靠方法。在一个案例研究中，这些物源技术将被应用于东南极山脉(6.5亿-4.8亿年前)的地质发展。本案例研究的目的是检验LIBS和EMP电气石分析在破译南极东部复杂地质历史中的有效性。这项研究有两个主要影响。首先，它将开发研究起源的新途径，以完善我们对地球历史的理解，使用广泛存在的矿物电气石。另一项社会效益是，电气石有可能从不同的宝石矿床中区分出来，这些宝石的价格完全不同。这项研究的样本、数据和技术将用于两所为少数群体服务的大学的本科生和研究生班，以培养下一代地球科学家。两所大学之间的学生交流将扩大他们的教育和分析经验，这对今天的S来说是必要的。这一研究团队包括两名女性联合个人助理，所有个人助理都是STEM学科中相当数量的女性的导师。除了与另一所以本科为重点的大学的教职员工合作外，与工业界的合作还将学者和行业合作伙伴聚集在一起，其中包括一家由女性拥有的营利性小企业。

Understanding Earth's geological history provides insight into processes that shape our planet and the distribution of economic resources. However, ancient geological events can be difficult to decipher because their physical presence may be lost to erosion. Fortunately, information on the types and ages of rocks (i.e., their provenance) that were present prior to weathering and erosion are encoded in some minerals that are preserved in sediments and sedimentary rocks. Tourmaline is one such mineral. It is a key repository of geologic information because it incorporates a wide range of chemical elements that reflect the rock environment in which it forms - that is, it encodes the chemical signature of that rock, similar to a fingerprint. Tourmaline is also a chemically and mechanically resistant mineral that, when weathered out of the rock in which it formed, it can become a sand grain that is incorporated into sediments (and rocks). Once it incorporates its original chemical signature, the tourmaline grain stores that signature for millions or billions of years.This work uses a synergistic approach to decipher former geological events, their record in sediments and rocks, by integrating chemical analyses of the mineral tourmaline using the new technology Laser-Induced Breakdown Spectroscopy (LIBS) with the established technology Electron Microprobe analyses (EMP). Both yield in-situ chemical fingerprints: LIBS is advantageous because it collects signals of all elements and their complexes, including the light elements, and provides relative compositions of elements, while EMP is a mature analytical technique and is used for highly precise and accurate micrometer-scale chemical data for most elements (except light elements H, Li). One goal of this work is to use these complementary techniques to develop robust approaches to provenance determination based on an extensive collection of tourmaline samples of known provenance. The provenance techniques will be applied, in a case study, to the geologic development of the East Antarctic Mountains (650-480 million years ago). The goal of this case study is to test the efficacy of tourmaline analysis by LIBS and EMP in deciphering complex geologic history of East Antarctic. This study has two major implications. First, it will develop new avenues of provenance studies to refine our understanding of Earth history using the widespread mineral tourmaline. An additional societal benefit is the potential to differentiate tourmalines from different gem deposits that command radically different prices. Samples, data and techniques from this study will be used in both undergraduate and graduate classes at two minority-serving Universities to educate the next generation of geoscientists. A student exchange between the two universities will broaden their educational and analytical experience, necessary for today?s global workforce. This research team includes two female co-PIs and all PIs serve as mentors to a significant number of women in STEM disciplines. Collaboration with industry brings together academics and industrial partners including a woman-owned for-profit small business, in addition to collaborations with faculty at another undergraduate-focused university.