How Continental Drift Is Powered By The Geomagnetogenic Process

Written by Koen Vogel, Ph.D. on December 14, 2022. Posted in Current News

Alternate models for planetary processes, part 2

This post is the second of seven in support of the PROM article “An integrated physical model characterizing planetary magnetism and heat,” which proposes an alternate origin of the geomagnetic field versus the consensus geodynamo theory.

Each post documents an alternate model to the existing scientific consensus on planetary processes. Post 2 deals with how the geomagnetogenic process is powering Earth’s heat anomalies and continental drift.

The prevailing theory of plate tectonics and continental drift

The Earth’s outer solid layers consist of a surficial, relatively cool, rigid crust termed the lithosphere, which sits on top of a more visco-elastic, deformable upper Mantle layer termed the asthenosphere. The lithosphere is divided into numerous tectonic plates that move relative to one another across the Earth’s surface, thereby affecting plate tectonics, the Earth’s main geologic process. The movement of the plates is largely due to asthenospheric convection cells driven by the large heat gradients between the Earth’s fluid Outer Core and its relatively cold lithosphere (Fig. 1). Two main forces drive the plate motion: friction forces between the convecting asthenosphere and the rigid lithosphere, and gravity forces due mainly to the slab pull of subducting plates at ocean trenches (Fig. 1). For this post the mid-Atlantic ridge, the plate boundary between the American plates to the west and the Eurasian and African plates to the east, will be used as an example, as the thermal mantle convection cells – not slab-pull – are likely the main driving force (Fig. 1).

Constructive plate boundaries are geologically long-lived features: for example, the mid-Atlantic ridge was likely first formed in the Triassic period, roughly 250 million years ago, and continues to this day to form new ocean crust between Eurasia and North America at a rate of roughly 25 mm per year. The origin and longevity of these long, curvilinear heat anomalies that form the constructive plate boundaries have remained enigmatic, that is no consensus theory exists on how and why these heat anomalies are created or endure for hundreds of millions of years.

Fig. 1: The driving forces of plate tectonics. Left: general schematic showing main components (Source: https://en.wikipedia.org/wiki/Mantle_convection); Right: Mid-Atlantic Ridge schematic

Fig. 2: (top) 1690 to 1990 average of the radial component of the geomagnetic field squared (Br2) at the core surface (after [3]; darker areas are higher; the dot-dash line is the magnetic equator); (middle): the spherical harmonic expansion (to degree 36) of conductive heat flow (after [4]); (bottom): Magnitude of the 1995 non-dipolar field (after [5]); black line represents the mid-Atlantic ridge.

The Covariation of Geothermal and Geomagnetic Data

Physical processes that are able to distribute and focus energy on planetary scales are rare, so planetary data sets that show significant spatial covariation – such as Earth’s geomagnetic and geothermal data – strongly suggest that a single process is responsible for their shared geometry. An Outer Core (OC) energy source likely powers both the geomagnetic field as well as the estimated 4 TW of heat lost by the Core to the Mantle via the Core-Mantle Boundary (CMB) [1,2]. Most energy forms readily convert to heat, but the reverse is a highly inefficient process: for example, an athermal dynamo is commonly believed to be responsible for the geomagnetic field, but its efficiency is likely on the order of 10-20% [1,2]. Therefore, a large percentage of the energy of any magnetogenic process should be observable as its waste heat signature. An integrated approach towards better characterizing the process consequently takes both thermal and magnetic data – and their evident spatial and temporal covariation (Fig. 2) – into account.

The Northern Hemisphere (NH) has two geomagnetic non-dipole (radial geomagnetic energy) highs centered around 55° N latitude and 90° W and 100° E longitude resp., locations that coincide with surface heat flow lows (Fig. 2). Both locations are in the center of their continental plates, remote from any constructive plate margins, and form the bullseye of oblong radial field strength and heat flow contours that are neatly bisected by the mid-Atlantic ridge curvilinear heat anomaly that follows the geomagnetic non-dipole field strength saddle between the two highs (Fig. 2 bottom; ~90° long. separation from each high).

An argument can be made that a relatively thick continental crust results in a lower surface heat flow than a thinner oceanic crust, but this cannot explain why – in a hemisphere that is ~60% covered by ocean – the geomagnetic non-dipole highs are located at the center of continental plates. No plausible feedback mechanism exists between the geomagnetogenic OC process and crustal composition or thickness, so the observed NH geomagnetic and geothermal geometries are likely caused by a single process that focuses radial magnetic energy (±20% of the energy) at the center of continental plates while focusing waste heat at the plate margins (±80% of the energy), thereby creating curvilinear heat anomalies and – at least partially – also driving continental drift [2]. Such reasoning could also explain why continental drift is absent on Earth’s sister planet, Venus, whose magnetic field is possibly non-existent [7].

In the Southern hemisphere (~80% covered by the ocean) the non-dipole locations are also close to land and remote from hot plate boundaries, though the case is not as convincing as its northern counterpart. Nevertheless, both geothermal lows (Fig. 2 middle) and historical radial field strength highs (Fig. 2 top) lie on roughly the same meridians as their northern counterparts. The 90° W and 100° E longitude lines also roughly coincide with the preferred virtual geographic pole (VGP) trajectories during recent magnetic reversals: transitional VGP paths are strongly biased to lie in the American 90° W meridian or its antipodal direction [1,3,6], again demonstrating the strong spatial correlation between geothermal and geomagnetic data.

Equatorial heat flow lows are centered on North Africa and the mid-Pacific Ocean, once again evidently remote from constructive plate boundaries, and unrelated to crustal composition.

Continental drift on other planets

Earth is the only planet in the solar system whose geology is largely controlled by plate tectonics and continental drift. The Gas Giants do not have a rigid lithosphere, and therefore cannot be expected to have a similar process. The other terrestrial planets (Mercury, Venus, Mars) do have a rigid lithosphere, though only Earth has a significant magnetic field: Mars has a very weak, possibly remnant field, Venus has no measurable field, and Mercury has an abnormally low field strength. Earth and Venus are chemically similar, and both have a rigid crust and hot spot volcanism, i.e. volcanism caused by upwelling Mantle plumes driven by radial heat and buoyancy effects [7]. Yet Earth’s geologic processes are largely dominated by plate tectonics: large curvilinear heat anomalies that originate in its Outer Core (e.g the mid-Atlantic ridge) drive Earth’s plate movements [2]. The absence of similar curvilinear anomalies on Venus has been speculatively attributed to the higher rigidity of its basaltic crust [7], yet a more likely explanation is that Earth’s magnetogenic process is also responsible for its curvilinear heat anomalies and that both are absent on Venus [7].

The link between geomagnetogenesis and curvilinear heat anomalies

The PROM article details how the geomagnetic field is generated by Solar Wind Induced Currents (SWICs), high-intensity, large-scale electrical currents that are powered by the solar wind and that circuit in the outermost shell of the Outer Core (OC). These circuits generate both a poloidal field, which creates the geomagnetic field, as well as a toroidal field, an Earth-internal field that generates heat at the circuit periphery. The hot circuit edges in turn act as high-temperature high-resistivity barriers, forming a stable feedback loop that ensures Earth’s geomagnetic field and heat anomalies, such as the mid-Atlantic ridge, remain relatively stable over millions of years. Fig. 3 presents a schematic of the Asian SWIC circuit and its associated continental heat anomalies.

Fig. 3: Schematic of the Asian SWIC circuit. Left; Asian SWIC circuit (grey line) on a World Geothermal Potential Map (Map Source: http://stellaeenergy.com/energy-transition-16-geothermal-energy); Right: schematic of the Asian SWIC circuit inducing poloidal (red) and toroidal (blue) magnetic fields. Note that the SWIC occurs in the outer shell of the Outer Core and not at Earth’s surface. Circled X’s reflect a magnetic moment into the page; dotted circles a magnetic moment out of the page.

Fig. 4 shows the Arctic region, where the two Northern Hemispheres SWIC circuits both originate and terminate. The PROM article documents that the northern hemisphere SWIC circuits form mutual inductance pairs with southern hemisphere SWIC circuits: the Asian circuit is paired to the Australian and Madagascar circuits, while the North American circuit is paired to a South American circuit. The mutual inductance of these loops causes their geomagnetic field contributions and SWIC strengths to rise and fall in a pairwise fashion. This is demonstrated by Fig. 5, which shows that between 1900 and 2020 the American loop pair decreased in strength, while the Asia-Madagascar pair increased in strength (See PROM article).

Fig. 4: Left: Schematic showing initial Northern Hemisphere SWIC loop directions (arrows), SWIC return direction (dashed arrows), and spawn times (numbers beneath arrows, GMT). AB = Amundsen Basin, compound black line = Gakkel Ridge spreading center between the North American and Eurasian Plate; Right: May-June 2020 temperature increases relative to 1981, showing Arctic heat anomaly in general, and the Asian positive and North American negative anomalies in particular. (Source: https://www.severe-weather.eu/global-weather/arctic-ocean-ice-melt-transpolar-fa/)

Fig. 5: Annual rate of change of IRF Total Geomagnetic Field Intensity between 1900-2020 (numbers are changed in nT/a; After [8])

1.     The asymmetrical heating of the Arctic Ocean: Fig. 4 demonstrates that the Arctic temperature anomaly is especially pronounced to the north of Asia, where the Asian SWIC strengths are increasing and generating more geothermal energy. The Gas Giants’ polar heat anomalies are generated similarly, though their SWIC strength increases are more seasonal in nature: during their summer solstice, the SWICs reach maximum strength at the summer pole.

2.     A geomagnetic excursion whereby the North Magnetic Pole (NMP) will possibly migrate to Asia: recent data [9] suggest that the NMP is currently moving NNW at a speed of 55 km/a. In 1900 its position (96° W, 70° N) lay near the North American non-dipole center (Fig. 2), but in 2022 its current trajectory puts it on-path to the Asian non-dipole center. The NMP speed can therefore be used as a proxy for the relative yearly strengthening of the Asia-Madagascar mutual inductance pair, and therefore also the Asian SWIC current strength and its Arctic heating. A plot of the NMP speed (Fig. 6) shows an excellent correlation with the IPCC-documented [1] periods (1900-1944; 1980-present) of Arctic warming and (1944-1964) cooling, further confirming that geomagnetic waste heat, and its resultant Arctic heat anomalies, should be taken into account as a Natural climate forcing.

Figures 6 and 7 demonstrate the strong correlation between the Arctic heat anomalies and the NMP speed: anomaly absence and below average speed in 1919, presence and above average speed in 1944, absence and below average speed in 1964, and presence and high speed in 2020.

Fig. 6: North Magnetic Pole speed versus time. The horizontal line roughly represents the 1900-1980 average. Data source: [9])

Fig. 7: North Pole heat anomalies between 1900-present. Upper left: no anomaly in 1919; Upper right: anomaly in 1944; Lower left: no anomaly in 1964; Lower right: anomaly in 2020. (Source: https://climate.nasa.gov/climate_resources/139/video-global-warming-from-1880-to-2021/

Alternate model 2: Continental drift is partially or largely driven by linear Outer Core heat anomalies generated by the Earth’s geomagnetogenic process.

[1]  Merrill, R.T., McElhinny, M. W., McFadden, P. L., 1998, The magnetic field of the earth: paleomagnetism, the core, and the deep mantle. Academic Press. ISBN 978-0-12-491246-5.

[2] Verhoogen, J., 1980, Energetics of the Earth. National Acad. of Sciences Collection, doi: 10.17226/9579

[3] Gubbins D., Love, J., 1998, Preferred VGP paths during geomagnetic polarity reversals: Symmetry considerations. Geophysical Research Letters, 25, 1079–1082. doi:10.1029/98GL00711

[4] Hamza, V. M., Cardoso, R. R., Ponte Neto, C. F., 2007, Spherical harmonic analysis of Earth’s conductive heat flow. Int J Earth Sci, 97, 205-226, doi: 10.1007/s00531-007-0254-3

[5] Lühr, H., 2000, CHAMP Magnetic Field Recovery. http://op.gfz-potsdam.de/champ/science/magnetic_SCIENCE.html Retrieved 16 August, 2021

[6] McFadden, P., Merrill, R.T., 1995, Fundamental transitions in the geodynamo as suggested by paleomagnetic data, Physics of the Earth and Planetary Interiors, 91, Pages 253-260, doi: 10.1016/0031-9201(95)03030-Z.

[7] Smrekar, S.E., Stofan, E.R., Müller, N., 2014, Venus: Surface and Interior. In: Encyclopedia of the Solar System (Third Edition), Academic Press ISBN: 978-0-12-415845-0, p. 323-341

[8] BGS (British Geological Survey) 2021, The Earth’s magnetic field: an overview. http://www.geomagnetism.bgs.ac.uk/education/earthmag.html  Downloaded 16 August 2021

[9] NOAA, 2021, (https://www.ngdc.noaa.gov/geomag/data/poles/NP.xy). Downloaded 2021 January 11

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