Final Report Summary - NANOPALEOMAG (Nanopaleomagnetism: a multiscale approach to paleomagnetic analysis of geological materials)
Paleomagnetism has played a pivotal role in developing our modern understanding of the Earth, and is one of the primary tools used by scientists to study the structure, dynamics and history of our solar system and the rocky bodies that exist within it. NanoPaleoMag has successfully developed new approaches to the paleomagnetic analysis of natural materials, enabling us to study natural magnetic signals in unprecedented detail. This approach has lead to breakthroughs in our ability to extract meaningful paleomagnetic information from the most ancient terrestrial rocks and extraterrestrial meteorites and has helped answer some of the most fundamental questions regarding the magnetic state of the early solar system.
At the heart of our pioneering NanoPaleoMag approach is a multi-scale workflow that allows us peer deep inside a rock or crystal and determine the precise location, size, shape and orientations of the nanoscale magnetic particles that carry the paleomagnetic information. Armed with this information, we perform sophisticated computer simulations of individual particles, mapping out the twists and turns of their internal magnetic structure, revealing complex patterns of swirling magnetic domains and vortices - nanoscale 'magnetic storms' that rage inside each particle as its magnetic structure adapts to the particle's size and shape and to the push and pull of the magnetic field of the planet or asteroid on which the rock formed.
This approach was used to study the magnetic field of the protoplanetary nebula – the factory of hot dust and gas in which the earliest solids in the solar system were formed. Chondrules (mm-sized spherical grains formed by rapid cooling and crystallisation of melt droplets) capture valuable information about the strength of the magnetic field within the nebula. The presence of strong nebular fields has long been hypothesised to explain the rapid rate at which material falls onto the growing Sun. Using the NanoPaleoMag workflow, the origin of stable magnetisation in chondrules was traced to ‘dusty olivine’ - a silicate mineral containing nanoscale inclusions of Fe metal. Our results contributed to the first reliable measurement of the nebula field, demonstrating that chondrules were likely to have formed either by shock waves passing through the nebula or by collisions between planetesimals, rather than some other mechanisms that would have involved much greater magnetic field strengths than observed.
Our unique approach has revolutionised the study of magnetism in metal-rich meteorites - materials that were previously thought to be unsuitable for paleomagnetic analysis. Using a state-of-the-art combination of nanometer to subnanometer resolution tomography and micromagnetic simulations, our work explained how the remarkable magnetic properties of iron meteorites are linked to the 3D chemical, crystallographic, and magnetic architecture of the ‘cloudy zone’ - a unique nanocomposite of ordered Fe-Ni alloys. By using innovative X-ray method of magnetic imaging, with unprecedented spatial resolution, we were able to use our new methods to trace the growth and decay of the magnetic field generated by the solidifying cores of asteroidal bodies.
Zircon crystals from the Jack Hills, Western Australia, are one of the few surviving mineralogical records of Earth’s first 500 million years. We located the presence of magnetic remanence carriers in ~ 4 billion year old zircon crystals, potential carriers of information about Earth’s earliest magnetic field. A combination of high-resolution transmission electron microscopy and computer simulations demonstrated that these ideal magnetic carriers formed several hundred million years after the original crystallisation age of the zircon. Our new understanding of the paleomagnetic properties of ancient zircon provide the platform on which a revolution in our understanding of Earth’s ancient paleomagnetic record can be built.
At the heart of our pioneering NanoPaleoMag approach is a multi-scale workflow that allows us peer deep inside a rock or crystal and determine the precise location, size, shape and orientations of the nanoscale magnetic particles that carry the paleomagnetic information. Armed with this information, we perform sophisticated computer simulations of individual particles, mapping out the twists and turns of their internal magnetic structure, revealing complex patterns of swirling magnetic domains and vortices - nanoscale 'magnetic storms' that rage inside each particle as its magnetic structure adapts to the particle's size and shape and to the push and pull of the magnetic field of the planet or asteroid on which the rock formed.
This approach was used to study the magnetic field of the protoplanetary nebula – the factory of hot dust and gas in which the earliest solids in the solar system were formed. Chondrules (mm-sized spherical grains formed by rapid cooling and crystallisation of melt droplets) capture valuable information about the strength of the magnetic field within the nebula. The presence of strong nebular fields has long been hypothesised to explain the rapid rate at which material falls onto the growing Sun. Using the NanoPaleoMag workflow, the origin of stable magnetisation in chondrules was traced to ‘dusty olivine’ - a silicate mineral containing nanoscale inclusions of Fe metal. Our results contributed to the first reliable measurement of the nebula field, demonstrating that chondrules were likely to have formed either by shock waves passing through the nebula or by collisions between planetesimals, rather than some other mechanisms that would have involved much greater magnetic field strengths than observed.
Our unique approach has revolutionised the study of magnetism in metal-rich meteorites - materials that were previously thought to be unsuitable for paleomagnetic analysis. Using a state-of-the-art combination of nanometer to subnanometer resolution tomography and micromagnetic simulations, our work explained how the remarkable magnetic properties of iron meteorites are linked to the 3D chemical, crystallographic, and magnetic architecture of the ‘cloudy zone’ - a unique nanocomposite of ordered Fe-Ni alloys. By using innovative X-ray method of magnetic imaging, with unprecedented spatial resolution, we were able to use our new methods to trace the growth and decay of the magnetic field generated by the solidifying cores of asteroidal bodies.
Zircon crystals from the Jack Hills, Western Australia, are one of the few surviving mineralogical records of Earth’s first 500 million years. We located the presence of magnetic remanence carriers in ~ 4 billion year old zircon crystals, potential carriers of information about Earth’s earliest magnetic field. A combination of high-resolution transmission electron microscopy and computer simulations demonstrated that these ideal magnetic carriers formed several hundred million years after the original crystallisation age of the zircon. Our new understanding of the paleomagnetic properties of ancient zircon provide the platform on which a revolution in our understanding of Earth’s ancient paleomagnetic record can be built.