Evolution of the Kerguelen LIP: Insights from Crystal Stratigraphy & Crystal Size Distributions from Site 1137, Elan Bank

摘要(尼尔-0452102)了解岩浆是如何演化的，对于了解火山喷发的原因很重要。对全岩样本的分析得出的成分只反映了熔岩在喷发前经历的平均过程。然而，对单个晶体和晶体群体的检查，可以更好地洞察岩浆演化的动力学。这项研究涉及圣母大学的研究人员，他们利用火成岩中不同群体的晶体(即晶体尺寸分布)，这些晶体具有相关的成核和生长历史。它将这种方法与矿物尺度的成分研究(即晶体地层学)相结合。这一组合方法限制了分异过程(即岩浆混合、地壳混染)的时间和程度，从而能够量化自岩浆体与其来源分离以来改变了岩浆体的过程的动力学和时间安排，并可能导致确定来源本身。这项研究利用南/南印度洋伊兰海岸科尔盖伦大火成岩省的样品，开发了一种新的技术，利用晶体尺寸分布和基于小波的相关性来确定大洋钻探计划1137站点7个共岩浆流中不同的斜长石晶体群，以重建岩浆室演化。样品的年龄范围为107-108 Ma，包括三个明显的岩浆活动断裂，以火山碎屑夹层为代表。这些火山碎屑单元将熔岩流序列划分为四个部分。每个部分都将从上、中、下三个层次进行学习。不同晶区的代表性斜长石晶体将通过电子探针、扫描电子显微镜和原位激光烧蚀电感耦合等离子体质谱进行主、次、微量元素分析。这些数据将允许确定分配系数，并重建母液组成和局部结晶环境。锶同位素测量将在一组晶体上进行，以进一步限制母质岩浆的成分和地壳污染的程度。晶体停留时间的独立估计将从晶体大小和地球化学数据中获得。更广泛的影响这项提议的广泛影响包括研究生的教育，以及新墨西哥州戴明市一所拉美裔占主导地位的高中的一所学校的一名K-12教师和学生的参与。这一努力将使西班牙裔高中生接触到地球化学和岩石学研究的兴奋。这项研究还涉及与英国达勒姆大学的研究人员进行国际合作。这项工作的成果将纳入圣母大学的研究生和本科生教学。还将建立一个“水晶地层学”网站，向公众和其他研究人员通报这项技术及其潜在的应用。

ABSTRACT (Neal - 0452102)Understanding how magmas evolve is important for knowing why volcanoes erupt. Analysis of whole-rock samples gives compositions that reflect only an average of the processes that the lava has experienced prior to eruption. Examination of individual crystals and crystal populations, however, provides better insight into the dynamics of magma evolution. This research involves researchers at the University of Notre Dame and utilizes different populations of crystals in igneous rocks (i.e., crystal size distributions) that have related nucleation and growth histories. It them combines this approach with mineral-scale compositional studies (i.e., crystal stratigraphy). This combined methodology constrains the timing and extent of differentiation processes (i.e., magma mixing, crustal contamination) that permits quantification the dynamics and timing of processes that have modified a magma body since separation from its source and can lead to identification of the source itself. The research uses samples from the Kerguelen Large Igneous Province on the Elan Bank In the Southern/South Indian Ocean to develop a new technique for reconstructing magma chamber evolution using crystal size distributions and wavelet based correlations to determine different plagioclase crystal populations in seven co-magmatic flows from Ocean Drilling Program Site 1137. Samples range in age from 107-108 Ma and encompass three distinct breaks in magmatism, which are represented by volcaniclastic interbeds. These volcaniclastic units divide the lave flow sequence into four parts. Each section will be studied from the top, middle, and base. Representative plagioclase crystals from different crystal zones will be analyzed for major, minor, and trace elements via electron microprobe, SEM, and in-situ laser ablation ICP mass spectrometry. These data will allow partition coefficients to be determined and the reconstruction of parent liquid compositions and local crystallization environments. Strontium isotope measurements will be made on a sub-set of crystals to further constrain parent magma compositions and the extent of crustal contamination. Independent estimates of crystal residence times will be obtained from the crystal size and geochemical data. Broader ImpactsBroader impacts of this proposal include education of a graduate student and involvement of a K-12 teacher and students at a school in a Hispanic dominated high school in Deming, New Mexico. This effort will expose Hispanic high school students to the excitement of geochemical and petrological research. The research also involves international collaboration with researchers at the University of Durham in the UK. Results of the work will be integrated into graduate and undergraduate teaching at the University of Notre Dame. A "crystal stratigraphy" web site will also be set up to inform the public and other researchers about the technique and its potential applications.