Details of Award
NERC Reference : NE/C518422/1
Silicate Hosted Magnetic Inclusions as Paleomagnetic Recorders
Fellowship Award
- Fellow:
- Dr JM Feinberg, University of Cambridge, Earth Sciences
- Grant held at:
- University of Cambridge, Earth Sciences
- Science Area:
- Terrestrial
- Marine
- Earth
- Overall Classification:
- Earth
- ENRIs:
- Natural Resource Management
- Global Change
- Science Topics:
- Planetary science
- Properties Of Earth Materials
- Tectonic Processes
- Mantle & Core Processes
- Abstract:
- The Earth has a magnetic field that is generated by liquid iron swirling around the planet's core. This magnetic field is what causes compass needles to swing northward. The flow pattern of this liquid iron is occasionally disrupted and needs time to re-establish itself. The magnetic field generated by this newly formed flow pattern may be oriented in the opposite direction than the pre-existing field. This directional flip of the magnetic field is called a reversal. If a reversal were to occur today, the new magnetic field would cause compass needles to swing southwards. Magnetic minerals in rocks record the history of these reversals throughout Earth's past. As rocks are formed during volcanism or sedimentation, the magnetic minerals 'lock in' according of the direction of the Faith's magnetic field. By measuring the magnetism of a rock sample, a scientist can determine the direction of the magnetic field at the lime the rock formed. If rocks of a variety of ages are measured, then a complete history of the Earth's magnetic field direction can be pieced together. The continuous history of Earth's magnetic reversals s called the paleomagnetic limescale, and the scientists who study it are called paleomagnetists. The paleomagnetic timescale is a tremendously useful scientific tool for studying the rate of plate tectonics, evolution, and basin development. Despite its utility, the existing paleomagnetic timescale covers only the last 7% of Earth history. The reason for this limited coverage is because the rock types normally used in paleomagnetic studies, such as basalt and limestone, become progressively more rare and altered with age. Rocks that have avoided alteration are not numerous enough to fully describe the magnetic field behavior during the three billion years encompassed within ancient geologic platforms. If it were possible to uncover the other 93% of the Faith's magnetic history, geologists could address questions about the evolution of the liquid core and origin of the solid inner core is well as the style of plate tectonics during in early Earth history. Paleontologists could more easily determine ages for fossil localities using the extended paleomagnetic timescale, and sratigraphers could describe sedimentation rates and basin development during the Precambrian (before ~550 Ma). Uncovering the magnetic history of the early Earth would aid problem solving across the full spectrum of geological and planetary sciences. For this early paleomagnetic window to open, a rock type is needed with the capability of maintaining a recording of the direction and intensity of the Earth's magnetic field over billions of years. Such a recorder must be stable in the face of variations in temperature, pressure, and chemical environment caused by common geologic processes such as metamorphism, weathering, and hydrothermal alteration. Magnetic inclusions in silicate minerals are one such medium. Silicate-hosted inclusions originate in one of two ways: as pre-existing grains 'swallowed up' (or occluded) by growing crystals or as inclusions precipitated inside a silicate mineral along regular directions during cooling. Silicate-hosted magnetic inclusions in recently formed rocks have been shown to record stable magnetizations consistent with the expected magnetic field orientation. Magnetic mineral inclusions are found in common minerals such as clinopyroxene and plagioclase, which are major constituents in preserved Precambrian rocks sequences. Additionally, because magnetic inclusions are isolated within their silicate hosts, they have the advantage of being protected against chemical alteration by hydrothermal fluids, and oxidation during high temperature laboratory experiments. Questions currently exist about the origins of magnetization of silicate hosted magnetic inclusions, which prevent their immediate use as paleomagnetic recorders. The two issues most deserving of attention are 1) the effects of microstructu
- NERC Reference:
- NE/C518422/1
- Grant Stage:
- Completed
- Scheme:
- Postdoctoral Fellow
- Grant Status:
- Closed
- Programme:
- Postdoctoral Fellowship
This fellowship award has a total value of £134,921
FDAB - Financial Details (Award breakdown by headings)
| Total - Staff | Total - T&S | Total - Other Costs |
|---|---|---|
| £101,221 | £5,199 | £28,500 |
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