Spatial and Temporal Ppatterns of Magmatism in the Oman Ophiolite: Constraints from High-Precision U-Pb Geochronology

阿曼蛇绿岩岩浆作用的时空模式：来自高精度 U-Pb 年代学的约束

• 批准号: 0727914
• 负责人: Samuel Bowring
• 金额: $ 18.04万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2010-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0727914&HistoricalAwards=false
• 关键词: Spatial; Temporal; Ppatterns; Magmatism; Oman

Intellectual Merit: This research will constrain the timescales of crustal growth and maturation in the Oman ophiolite, part of the Cretaceous oceanic lithosphere that was thrust onto the continent as a result of plate tectonic processes. Uranium-lead zircon geochronology will be used to determine the crystallization ages of the extensive gabbro and lesser plagiogranite bodies that compose the intrusive crust of the ophiolite to better than 0.05 0.1%, corresponding to absolute age errors of 50,000 90,000 years for the samples to be studied. Closely spaced samples will be collected during field work in Oman on three dimensional exposures of the ophiolite. Samples will be examined for zircons and zircons will be separated from the matrix and chemically abraded to remove alteration. Thermal ionization mass spectrometry will be used to determine high precision uranium and lead isotopic compositions which can be used to determine the age of the zircons. Goals will be to use high precision geochronology to resolve variations in intrusive magmatism in time and space during the formation of the oceanic lithosphere. The work will provide new insights into the role of intrusive off-axis magmatism at mid-ocean ridges. Broader Impacts: Broader impacts of the work center on support of an early career scientist and inter-institutional collaboration. Work will also support the repositioning of the radiogenic isotope laboratory at MIT to allow it to investigate the origin and evolution of oceanic lithosphere as part of the long-term goals of the EARTHTIME initiative, an international effort to intercalibrate radiogenic dating techniques and use high-precision geochronology for understanding earth processes.

智力优势：这项研究将限制阿曼蛇绿岩的地壳生长和成熟的时间尺度，白垩纪海洋岩石圈的一部分，被推到大陆板块构造过程的结果。铀-铅锆石年代学将被用来确定结晶年龄的广泛辉长岩和较小的斜长花岗岩体组成的侵入地壳的蛇绿岩优于0.05 - 0.1%，对应的绝对年龄误差为50,000 - 90,000年的样品进行研究。在阿曼进行蛇绿岩三维暴露的野外工作期间，将收集密集的样品。 将检查样品中的锆石，并将锆石从基质中分离出来，并进行化学研磨以去除蚀变。 热电离质谱法将被用来确定高精度的铀和铅同位素组成，这可以用来确定锆石的年龄。 目标将是利用高精度的地质年代学来解决在海洋岩石圈形成过程中侵入岩浆活动在时间和空间上的变化。 这项工作将为大洋中脊侵入性离轴岩浆作用的作用提供新的见解。更广泛的影响：工作中心对支持早期职业科学家和机构间合作的更广泛影响。 这项工作还将支持麻省理工学院放射性同位素实验室的重新定位，使其能够调查海洋岩石圈的起源和演变，作为EARTHTIME倡议长期目标的一部分，该倡议是一项国际努力，旨在相互校准放射性测年技术，并利用高精度地质年代学了解地球过程。