Global Expansion Tectonics: A Significant Challenge for Physics

Scientific Paper
Title	Global Expansion Tectonics: A Significant Challenge for Physics
Read in full	Link to paper
Author(s)	James Maxlow
Keywords	expansion tectonics, plate tectonics, seafloor spreading, Earth radius, Gravity
Published	2012
Journal	Proceedings of the NPA
Volume	9
No. of pages	11
Pages	363-373

Read the full paper here

Abstract

A very important geophysical contribution to appreciating modern tectonic theory has been the completion of seafloor magnetic mapping, plus radiometric and paleontological age dating of seafloor crusts beneath all Earth's oceans. This seafloor mapping places finite spatial and temporal constraints on the crustal plate motion history within all of the ocean basins, back to the Early Jurassic Period (approximately 170 million years ago). The magnetic patterns and age dating determined during this seafloor mapping program were historically interpreted as evidence for seafloor growth and spreading, which led to the promotion of Plate Tectonic theory during the 1960s – a theory that adopts and continues to insist on the fundamental premise that Earth radius remains constant with time. In contrast, by removing this premise and allowing Earth radius to vary with time, this same seafloor mapping provides us with a unique opportunity to accurately measure past Earth radius, to both latitudinally and longitudinally constrain plate assemblages on smaller radius Earth models, and to quantify a rate of increase in crustal surface area, and hence radius throughout Earth history; giving rise to the alternative tectonic theory called Global Expansion Tectonics. Mathematical modeling of this seafloor mapping shows that Earth radius is increasing exponentially through time, and radius is currently increasing at a rate of 22 millimetres per year. While this seafloor mapping quantifies Global Expansion Tectonics as a viable alternative to conventional tectonic theory, a fundamental challenge is presented to physics, whereby an explanation is required to explain how and where additional matter is generated and accumulated within the Earth in order to comply with the increase in Earth radius, as evidenced from empirical seafloor crustal data.

Overview

James Maxlow's NPA paper is a compressed statement of the case he set out at length in his 2001 Curtin University doctoral thesis and in Terra non Firma Earth. Its structure is unusual for a dissident paper: rather than attacking the geological data, Maxlow accepts the seafloor magnetic striping and age dating of the 1990 CGMW/UNESCO Bedrock Geological Map of the World as given, and argues that a single premise — that the Earth's radius has been constant — was smuggled in with plate tectonics rather than measured. Remove the premise, he argues, and the same mapping yields a direct measurement of ancient Earth radius.

The result is a quantitative model: an exponential increase in radius from an Archaean proto-Earth of about 1,700 km to today's 6,371 km, with a present-day rate of 22 mm per year. Maxlow is explicit that this leaves the physics unsolved, and the paper's title is a challenge rather than a claim: "what mechanisms are available to explain the undeniable empirical geological evidence?" The mainstream account he displaces is subduction, which on his reading exists only "for maintaining a static radius Earth premise".

The argument

The lineage

Maxlow traces the idea from Ortelius (1596), through Mantovani (1889, 1909), Lindemann (1927), Hilgenberg's small-Earth globes of the 1930s, Sam Warren Carey from the 1950s, and Koziar and Vogel in the 1980s. The pivot is Carey's 1958 observation that a Pangaean reassembly on a modern-sized globe fits well at the centre but "became progressively imperfect away from these areas", and that the fit "could be made much more precise ... if the diameter of the Earth was smaller at the time of Pangaea". Hilgenberg and Vogel found that the continents envelop a globe of about 55–60% of present radius, which Maxlow calls a coincidence in need of explanation.

Measuring ancient radius from seafloor area

The measurement is direct. The bedrock map is redrawn as a 24-gore sinusoidal projection, chosen because it is true to scale and can be pasted onto a globe. Each dated seafloor stripe is digitised and its area measured; subtracting the cumulative area of all crust younger than a given age from the present 51.0 × 10⁷ km² leaves the ancient surface area, and hence the ancient radius. Table 1 gives ten intervals: 6,337 km at 1.9 Ma, 5,931 km at 23 Ma, 4,889 km at 84 Ma, down to 4,038 km at 205 Ma. The assumption is that all area increase is confined to seafloor, continental increase being taken up by crustal stretching.

The exponential law

Linear regression on the cumulative area data was best fitted by exponential growth. Writing ln(R_a/R₀) = At + B and finding the intercept B negligible, Maxlow arrives at

R_a = (R₀ − R_p)e^kt + R_p,  k = 4.5366 × 10⁻⁹/year

with R_p ≈ 1,700 km, the primordial Archaean radius obtained by stripping sediments and magmatic rocks back to the mantle in the small-Earth models. The curve is nearly flat for the first three billion years — about 60 km of growth — then accelerates; by the late Permian the crust could stretch no further and Pangaea ruptured.

Kinematics

From equation 6 the present-day rates follow: dR/dt = 22 mm/yr, dC/dt = 140 mm/yr, dS/dt = 3.5 km²/yr, dV/dt = 11,000 km³/yr. Maxlow compares these with published areal spreading rates — Steiner (1977) 3.19 km²/yr, Garfunkel (1975) 3.15, Parsons (1982) 3.45 — and with early space-geodetic figures of 24 ± 8 mm/yr (Parkinson) and 18 mm/yr (Robaudo & Harrison 1993).

Two endpoint scenarios are then examined. At constant mass, density rises backward in time to about 290 g/cm³ and surface gravity to about 138 m/s² in the Precambrian — figures Carey rejected as impossible. At constant density, mass instead grows from about 1.1 × 10²³ kg to today's 5.97 × 10²⁴ kg, giving present rates of dM/dt = 60 × 10¹² tonnes/yr and dg/dt = 3.4 × 10⁻⁸ m s⁻²/yr, with Mesozoic surface gravity about half of today's — which Maxlow notes "could very well have benefited" the dinosaurs. Extrapolated forward, the Earth approaches giant-planet size in roughly 500 million years.

The proposed cause

Following Carey, mass increase is taken as the primary driver, and the source is placed in a plasma-dominated universe: the Earth's magnetic field gathers anions and cations bombarding it from space, chiefly from the Sun, which penetrate deep within and reconstitute matter at the core–mantle interface. The resulting mantle swell is expressed at the surface as crustal extension along the mid-ocean rifts. Maxlow calls the model "still largely speculative" and quotes Creer (1965) that we "should beware of rejecting the hypothesis of Earth expansion out of hand on grounds that no known sources of energy are adequate".

Assessment

The paper's arithmetic is correct throughout, and unusually easy to check because Maxlow prints his raw data. The area-to-radius conversion in Table 1 is right: 51.0 × 10⁷ km² gives √(S/4π) = 6,370.6 km, and the last row, 20.4934 × 10⁷ km², gives 4,038 km exactly as tabulated. Equation 6 with k = 4.5366 × 10⁻⁹/yr gives dR/dt|₀ = 21.2 mm/yr, consistent with the quoted 22, and reproduces the tabulated radii to within about 0.4% out to 84 Ma. Every derived rate follows: 2π × 22 = 138 ≈ 140 mm/yr for circumference, 8πR·dR/dt = 3.52 km²/yr for area, 4πR²·dR/dt = 11,200 km³/yr for volume, ρ times that = 6.2 × 10¹³ tonnes/yr for mass, and (4/3)πGρ·dR/dt = 3.39 × 10⁻⁸ m s⁻²/yr for gravity. The constant-mass Precambrian figures also check: 5.97 × 10²⁴ kg in a 1,700 km sphere is 290 g/cm³ and gives g = 138 m/s². This is a numerically careful paper, and it deserves to be said plainly.

The internal weaknesses are minor by comparison. The oldest tabulated radius, 4,038 km at 205 Ma, is not reproduced by equation 6, which gives 3,543 km — a 12% shortfall that the paper acknowledges in the Figure 6 caption and attributes to continental-slope sediments. The Parsons conversion is slightly inconsistent: 3.45 km²/yr converts to 21.5 mm/yr by the same formula that turns Steiner's 3.19 into 20, not to the 23 quoted. And equation 6 gives 46,800 km at +500 Myr, between Neptune and Saturn in size, reaching Jupiter's 71,500 km only at about 600 Myr.

The real difficulties are external, and they are severe. First, the rate is directly measured and it is not 22 mm/yr. The space-geodesy figures Maxlow cites — Parkinson's 24 ± 8 mm/yr, Robaudo & Harrison's 18 mm/yr — predate a stable global reference frame, and a uniform radius change is largely absorbed into the frame's scale parameter unless the scale is independently tied to SLR and VLBI. When that was done properly with ITRF2008, Wu and colleagues (2011) found a mean change in Earth radius of 0.1 ± 0.2 mm/yr, which excludes 22 mm/yr by roughly a hundred standard deviations. Independently, palaeomagnetic determinations of ancient Earth radius constrain it to within a few percent over the past 400 Myr, whereas Maxlow's curve requires the radius at 205 Ma to have been 63% of today's.

Second, the areal spreading rates are not independent confirmation. Steiner, Garfunkel and Parsons measured the rate at which new seafloor is created; that is exactly the quantity plate tectonics says is balanced by consumption at trenches. Converting an accretion rate into a radius increase presupposes that no crust is destroyed, which is the point at issue, so the agreement is circular. And subduction is not merely a bookkeeping device: it is observed in Wadati–Benioff earthquake zones that dip continuously to 660 km, in seismic tomography that images cold slabs descending into the lower mantle, in the slab-derived geochemistry of arc volcanoes, and in accretionary prisms and obducted ophiolites. The paper does not address any of this evidence, which is the strongest reason the constant-radius premise is not, as it claims, an untested assumption.

Third, the proposed mechanism fails quantitatively by a very wide margin. The Sun sheds roughly 4 × 10¹⁶ kg per year in the solar wind; the Earth's geometric cross-section intercepts about 4.5 × 10⁻¹⁰ of it, or some 2 × 10⁷ kg per year. The model requires 6 × 10¹⁶ kg per year — nine orders of magnitude more, and more than the Sun loses in total. Magnetospheric focusing cannot bridge a gap of that size, and in any case the Earth's magnetosphere deflects the solar wind rather than funnelling it into the core. The same accretion, if it occurred, would be visible as an anomalous secular increase in GM_⊕, which lunar laser ranging and satellite tracking constrain very tightly.

Finally, the "better than 99% fit-together" is offered without a stated metric or a null test. Reassembling continents on a globe of freely chosen radius has more degrees of freedom than a fixed-radius reconstruction, so a better fit is expected even if the hypothesis is false; the fit quality only becomes evidence when the same procedure is shown to fail on synthetic data generated under the constant-radius alternative. Maxlow's honesty about the missing mechanism is genuine and creditable, and the challenge he poses is properly posed — but it is a challenge that space geodesy has since answered in the negative, and the paper's own kinematics are what make that answer decisive.

See also

• James Maxlow
• Expansion Tectonics
• Gravity
• Mass
• Plasma