INSPIRE: Search for Records of the Hadean Dynamo from Detrital Zircons

这是一个INSPIRE奖，由地球科学局(地球物理计划、岩石学和地球化学计划)和数学和物理科学局(原子、分子和光学实验物理)的项目共同资助，以及来自OIA-INSPIRE和OISE的联合资助。地球磁场是由金属核心中的流体运动产生的，这一过程被称为地球发电机。在地球历史的头10亿年里，地球发电机的起源时间和强度基本上是未知的。地球发电机的早期历史对地球的热演化、磁场产生的物理学以及早期地球的宜居性具有重大影响。据我们所知，在这个最早的时代，唯一可能记录这一领域的矿物是在西澳大利亚沉积岩中发现的锆石(ZrSiO4)晶体。它们的年龄长达43.8亿年，是已知的最古老的陆地矿物。在这里，调查小组开发了一个测量这些晶体的磁化强度的项目，该项目得到了美国国家科学基金会促进跨学科研究和教育(INSPIRE)计划的支持，可能最终确定地球发电机的起源和最早演化时间。该项目是来自七个机构的地球物理学家、地球化学家、地质学家和物理学家之间的国际合作，包括超高灵敏度磁学、量子科学、辐射测年、野外地质学、矿物学和稳定同位素地球化学的领军人物。它支持开发用于分析极弱磁性材料的下一代磁测量技术和用于确定地球早期样品的蚀变历史的地球化学技术。它还为三所大学的研究生培训提供资金，这些研究生将参与国际现场工作以收集样本，以及参与跨学科科学。该项目的核心挑战是确定锆石磁化的起源时间。以往的古地磁、地球化学和矿物学分析表明，寄主岩石和许多锆石在形成后都发生了广泛的再磁化作用。该团队建议确定西澳大利亚的热历史和蚀变历史，并研究来自西澳大利亚的大量超过40亿年的锆石的剩余磁化作用。为了实现这一目标，他们将描述锆石寄主岩石的地质和地层学特征，并使用U-Pb地质年代学确定锆石年龄。他们将使用两种新的超高灵敏度磁测量技术：超导量子干涉装置(SQUID)显微镜(SM)和量子钻石磁测量(QDM)]来分析锆石的极弱磁化作用。最后，将使用各种微观分析技术来确定哪些颗粒具有主要的铁磁性包裹体。为了让其他人能够独立测试这些结果，该团队将创建一个开放的档案，记录他们的关键测量结果和样本，供其他研究人员查阅，并将他们的磁强计上的时间提供给合格的研究人员。

This is an INSPIRE award, which is being co-funded by programs in the Geoscience Directorate (Geophysics Program, Petrology and Geochemistry Program) and Math and Physical Sciences Directorate (Atomic, Molecular, and Optical Experimental Physics), as well as co-funding from OIA-INSPIRE and OISE. The Earth's magnetic field is generated by fluid motions in the metallic core, a process known as the geodynamo. The time of origin and intensity of the geodynamo during the first ~1 billion years of Earth history are essentially unknown. The geodynamo's early history has major implications for the thermal evolution of the planet, the physics of magnetic field generation, and the habitability of the early Earth. The only minerals of which we are aware that might record the field during this earliest epoch are zircon (ZrSiO4) crystals found in sedimentary rocks in Western Australia. Ranging up to 4.38 billion years in age, they are the oldest known terrestrial minerals. Here the investigating team has developed a project to measure the magnetization of these crystals, supported by the Integrated NSF Support Promoting Interdisciplinary Research and Education (INSPIRE) program, that could finally determine the geodynamo's time of origin and earliest evolution. This project is an international collaboration between geophysicists, geochemists, geologists, and physicists from seven institutions and includes leaders in ultrahigh sensitivity magnetometry, quantum science, radiometric dating, field geology, mineralogy, and stable isotope geochemistry. It supports the development of next-generation magnetometry techniques for the analysis of extremely weakly magnetic materials and geochemical techniques for determining the alteration histories of samples from the early Earth. It also funds the training of graduate students at three universities, who will participate in the international field work to collect samples, as well as in the interdisciplinary science.The central challenge of this project is to determine the time of origin of the zircons' magnetization. Prior paleomagnetic, geochemical and mineralogical analyses have shown that the host rocks and many zircons have been pervasively remagnetized well after they formed. This team proposes to determine the thermal and alteration histories and study the remanent magnetization of numerous zircons older than 4 billion years from Western Australia. To achieve this, they will characterize the geology and stratigraphy of the zircon host rocks and determine zircon ages using U-Pb geochronometry. They will analyze the extremely weak magnetizations of the zircons using two new ultrahigh-sensitivity magnetometry techniques: superconducting quantum interference device (SQUID) microscopy (SM) and quantum diamond magnetometry (QDM)]. Finally, a variety of microanalytical techniques will be employed to establish which grains have primary ferromagnetic inclusions. So that others can independently test these results, the team will create an open archive of their key measurements and samples accessible by other researchers and make time available on their magnetometers to qualified researchers.