The evolution of the early solar system and early Earth inferred from paleomagnetism

点击翻译按钮获取中文摘要

During the ~5 Myr following the formation of the Sun, our solar system is thought to have undergone a vast array of transformations as it quickly transitioned from a chaotic cloud of dust and gas into an organised disk of protoplanets and asteroids [1]. The transfer of mass and angular momentum within the solar system during this short period is believed to have played a central role in this process. Mass and angular momentum transfer have been predicted to have been governed by ancient magnetic fields present within the collapsing nebula, however astronomical measurements of these fields in other solar systems have only provided weak constraints on their properties. Magnetic measurements of meteorites that formed within the first 5 Myr of our solar system could therefore provide unique constraints on the lifetime, intensity and evolution of these crucial magnetic fields [2]. Furthermore, we are yet to obtain a direct measurement of a young internally-generated planetary field from a body in another solar system. Complimentary magnetic measurements of ancient terrestrial samples could therefore provide key constraints on the thermal evolution and accretion of the proto-Earth.In this project, the student will focus on the experimental study of the magnetism carried by different components within a range of meteorites and ancient terrestrial samples using a variety of cutting-edge techniques (predominantly paleomagnetic techniques with possible complimentary geochemical measurements). Ideally, these data will be accompanied by modelling to assist with their interpretation. The overall aim will be to reliably infer the properties of the ancient magnetic fields experienced by these samples and to use the observations to better understand the early evolution of the proto-Earth, asteroids, the solar nebula and the Sun. The student will be joining a international team of researchers working in collaboration on this problem, and there is the possibility of extended visits to MIT, Harvard and/or the Lawrence Berkeley Labs to obtain data. The student will use both traditional and pioneering paleomagnetic techniques to perform their research. These will include magnetometry of bulk samples, and novel magnetic microscopy (superconducting quantum interference device, magnetic tunnel junction, quantum diamond microscopy [3] and/or photoelectron emission microscopy) of micro- to nano-scale magnetic materials within these samples. There will be opportunities for the student to dictate the direction of the research, including the possibility of developing these pioneering techniques on top of the acquisition of novel data. Data acquisition will be accompanied by structural characterisation using electron microscopy and magnetic characterisation using magnetic hysteresis techniques and magnetic microscopies. The student will also ideally perform models of thermal evolution and magnetic field generation within planetary bodies and the solar nebula to best interpret their observations. Together, the combination of these approaches will provide the most rigorous understanding of early magnetic activity within the solar system and will provide the student with a variety of useful experimental and theoretical skills.