Global expansion tectonics
Exponential Earth Expansion from the Pre-Jurassic to the Present
by James Maxlow
Table of Contents
- Global expansion tectonics
- Earth dynamics
- Quantitative modeling
- Geological implications
- Summary and conclusions
Welcome
It is unfortunate that the concept of "plate tectonics" is now so firmly entrenched in our scientific community that geoscientists, teachers, and students are blinded to all new developments in global tectonics.This article is presented as a reminder that, strictly speaking, all is not well with plate tectonics. The primary aim of this article is to demonstrate to you that, utilizing modern geological and geophysical data to globally constrain the spatial and temporal plate motion history of all crustal plates, an expanding Earth tectonic model can provide a viable alternative to conventional palaeomagnetic-based plate tectonics.
Global Expansion Tectonics
Global Expansion Tectonics is presented as a revitalized thesis of Earth expansion which utilizes published oceanic magnetic isochron and continental geological and geophysical data (e.g. Larson et al, 1985; CGMW & UNESCO, 1990) to empirically constrain both palaeoradius and plate reconstruction from the Archaean to the Present. Global Expansion Tectonics is quantifiable both empirically and mathematically by assuming that the Earth's lithospheric budget; in particular the increase in ocean sea floor surface area at the mid-ocean-rift zones, has been cumulative with time, and the surface area of oceanic lithosphere has been fully fixed in the rock record. A mathematical relationship for the rate of change of palaeoradius with time was determined by considering the exponential increase in cumulative surface area, from the Archaean to the Present, of both oceanic and continental lithosphere. By using the method of least squares to calculate gradients of curves of best fit, an equation for rate of Earth expansion was then established, and applied to a study of the kinematics of Earth expansion.
In the concept of Global Expansion Tectonics, prior to the Early Jurassic, modern deep ocean basins did not exist. All continental lithosphere was united to form a single Pangaean super continent enclosing the Earth at a much-reduced palaeoradius, with the volume of hydrosphere and atmosphere increasing with time in sympathy with the volume of oceanic lithosphere. This increase in hydrosphere and atmosphere is considered to have resulted from mantle devolitilisation, as a natural response to a decrease in surface gravity and mantle temperature and pressure conditions with time. Oceanic areas during the pre-Jurassic were considered to be represented by shallow, intra or epi-continental seas, with deposition of sediments within deeper "geosynclinal" sedimentary basins masking all evidence of sea floor spreading.
Pre-Jurassic small Earth models for the Palaeozoic and Neoproterozoic indicate that the primordial Archaean Earth ("Primordia") was approximately 1700 kilometres radius, and remained relatively static throughout the Archaean to late Mesoproterozoic. This accords well with published literature which suggests that there is no evidence for Earth expansion prior to the Mesoproterozoic, and the scarcity of evidence for horizontal crustal movements places constraints on the extent of expansion prior to the upper Proterozoic. The dominance of tensional tectonics during the Archaean and Proterozoic however, suggests also that some degree of expansion may have occurred by crustal dilation associated with faulting and rifting.
So What's New?
Oceanic magnetic isochron data (CGMW & UNESCO, 1990) was utilised during early research into Global Expansion Tectonics to empirically constrain both plate configuration and palaeoradius at a much-reduced Earth radius. The small Earth models constructed during this research demonstrated unequivocally that, if the Earth has expanded since at least the Early Jurassic then, small Earth reconstructions coincide fully with the spreading and geological crustal data, and requires explaining. Something which, globally, plate tectonic reconstructions still cannot get right.
In constructing the small Earth models displayed within the Global Expansion Tectonics document it was argued that, in order to quantify any variation in the Earth's palaeoradius, and constrain plate configuration with time, it is necessary to take into account the area and pattern of oceanic lithosphere. By moving backwards in time from the present, successively older chron intervals from across active spreading ridges must be removed, and each of the remaining chron intervals reunited along their common spreading ridges. The series of small Earth models shown in the figure below were constructed by simply subtracting the next youngest chron interval from the previous model, and refitting the plates together at a reduced Earth radius.
The small Earth models shown in the figure demonstrate that, if the Earth has expanded, small Earth reconstructions coincide fully with the sea floor spreading and continental data. These small Earth models consistently demonstrate a greater than 99% fit-together of all plates, for each chron interval shown, and suggests that the surface area of oceanic lithosphere measured for each chron interval represents the total area of new oceanic crust, generated and preserved during the interval of time under study. Thus empirically negating the need for removal of excess lithosphere by subduction processes. These models are now on permanent display at the Geological Museum of the Polish Geological Institute, Warsaw.
Most Frequently Asked Objections
Acceptance of the theory of Earth expansion is currently envisaged by researchers to be thwarted by major obstacles which supposedly "outnumber the evidence in favour". The most commonly perceived problems include an explanation for the existence of the two very different extensional structures exposed on the oceanic floors: the mid-oceanic ridges and the trench-arc/back-arc zones, characterized by very different seismicity and volcanism; the problem of atmospheric and hydrospheric accumulation on an expanding Earth; and the adaptation of palaeomagnetics to a constantly variable Earth radius. Frequently asked objections to Earth expansion include:
What about the Pre-Jurassic?
In Global Expansion Tectonics, prior to the Early Jurassic, modern deep ocean basins did not exist. All continental lithosphere was united to form a single Pangaean supercontinent enclosing the Earth at a much-reduced palaeoradius. Oceanic areas during the pre-Jurassic were represented by shallow, intra- or epi-continental seas with deposition of sediments within deeper "geosynclinal" sedimentary basins masking all evidence of sea floor spreading. The Global Expansion Tectonic Precambrian Earth expansion process, shown below, is considered to have been very much subdued, prior to development of intra or epi-continental Palaeozoic "geosynclinal" sedimentary basins, leading to post- Mesozoic crustal breakup and continental dispersal.
Empirical small Earth models for the Palaeozoic and Neoproterozoic indicate that the primordial Earth size for the Archaean was approximately 1700 kilometres radius and remained relatively static throughout the Archaean to late Mesoproterozoic. If you have trouble with this statement remember that, at approximately 15 to 20 billion years, i.e. between six and eight figure widths to the left, the entire Universe was supposedly a singularity (zero) prior to the "Big Bang". The increase in palaeoradius during the Archaean to late Mesoproterozoic was approximately 60 kilometres. This accords well with published literature which suggests that there is no evidence for Earth expansion prior to the Mesoproterozoic, and the scarcity of evidence for horizontal crustal movements places constraints on the extent of expansion prior to the upper Proterozoic. The dominance of tensional tectonics during the Archaean and Proterozoic however suggests also that some degree of expansion may have occurred by crustal dilation associated with faulting and rifting.
Where does the additional mass come from?
This is a very difficult question to answer. Because, in the past, the Earth has always been considered static in size it has not been necessary to ask the question. From the mathematical relationship established for the rate of change of palaeoradius from the Archaean to the Present it was calculated that the Earth is undergoing an exponential expansion at the present rate of 21 mm/year, commencing from an Archaean primordial Earth size of approximately 1700 kilometres radius. Where the additional mass comes from is therefore a valid question. Researchers elsewhere consider that the Earth is expanding because of an exponential increase in mass with time, e.g. matter is the antithesis of energy, however the kinematics of an exponentially expanding Earth suggests that mass may possibly have been constant with time resulting in a reduction in density and surface gravity. The ultimate cause of Earth expansion must however be considered intimately related to a cosmological expansion of the Universe, i.e. where does the mass of the Universe come from?
What about the ocean water and atmosphere?
Researchers have argued that, for a pre-Jurassic small Earth with a continuous continental crust, a large expansion process implies that the entire Earth would have been covered by an ocean with an average depth of 6.3 kilometres. Global Expansion Tectonics however considers that during Earth expansion, the whole column of atmosphere, hydrosphere, oceanic lithosphere and underlying mantle has been added at an accelerating rate through geological time, accreted primarily at the growing ridges and rift zones. As the ocean waters and ocean floors both have the same origin it is to be expected that they would be produced pari passu, with the generation of ocean water and atmosphere keeping pace with the growth of oceanic lithosphere. This increase in hydrosphere and atmosphere is considered to have resulted from mantle devolitilisation, as a natural response to a decrease in surface gravity and mantle temperature and pressure conditions with time. This devolitilisation process may also represent a prime mechanism for mineralisation.
What about orogenesis?
Brunnschweiler, in a paper dealing with the evolution of geotectonic concepts in the past century, considered that Earth expansion was essentially a radial movement and therefore its tangential plate displacements are only apparent, not real. The possibility of orogenesis developing under these conditions of radial expansion was discounted because the necessary vertical movements did not appear to explain the observed compressional features. It is unfortunate that this "radial expansion" concept has crept into the published literature. As Carey first recognized, the present Earth has a hemihedral asymmetry, with an antipodal distribution of continents and oceans. What this implies is that the southern continents have separated much greater distances than those of the northern hemisphere, with a much greater insertion of new oceanic lithosphere in the southern hemisphere. Small Earth modeling confirms that the Earth expansion process is asymmetric, not radial, and therefore plate motion is made up of both tangential and radial vector components. Within Global Expansion Tectonics, orogenesis is considered intimately related to an asymmetric expansion of the Earth, resulting from intra-cratonic interaction during gravity induced relief of surface curvature. The radial and tangential vector components of this asymmetric expansion process giving rise to the required continuum of orogenic models, varying from compressional to translational and torsional.
What about subduction?
The apparent overriding of the north Pacific Ocean plate by North America and Australia is often quoted as a classic example of plate consumption by subduction. In all conventional Late Triassic to Mid-Jurassic reconstructions of Pangaea, on constant radius Earth models, the area of the Pacific Ocean is increased essentially by the sum of the areas of the Atlantic and Indian Oceans, less that of the "Tethyan" and "Palaearctic" Oceans. This early Mesozoic "Panthallassa" Ocean would have possessed an oceanic crust generated during the Triassic and Palaeozoic at least. The Mesozoic and Cenozoic history would therefore be one of east-west and north-south contraction of the oceanic area to the size of the modern Pacific Ocean, subduction of all pre-Mesozoic crust, and subduction of a substantial quantity of oceanic crust generated during the Mesozoic to Cenozoic. Global Expansion Tectonics suggests however that, when the circum-Pacific continents are reassembled onto small Earth models, the necessity for such an expansive pre-Mesozoic "Panthallassan Ocean", and similarly a "Tethyan Ocean", disappears. Subduction of between 5,000 to 15,000 kilometres of Pacific oceanic lithosphere therefore becomes unnecessary. Instead, by consideration of the spherical spatial and temporal plate motion history of the Earth as a whole, this north Pacific Ocean region is interpreted as a region of Mesozoic asymmetric spreading history evolving towards Cenozoic symmetric type spreading. A value of 21 mm/yr, calculated for secular increase in Earth radius, is considered adequate to account for all of the ocean floor growth since at least the Early Jurassic, without the need for consideration of subduction of oceanic lithosphere.
What about palaeomagnetics?
Palaeomagnetics has long been considered the cornerstone of plate tectonics. Fundamental premises regarding the constancy of continental surface area, used to determine palaeoradius, however stem from the early 1960s, prior to the development of modern global tectonic concepts, or completion of the oceanic crustal database. Mathematical equations were developed by palaeomagneticians from conclusions insisting that continental surface areas have remained essentially constant, hence any variation in palaeoradius was concluded to have been negligible with time. Since these equations were first derived, modern plate tectonic concepts have demonstrated that the Earth's crust is not a passive adjunct of lithospheric plates, but a dynamic, interactive layer of the Earth. Modified palaeomagnetic equations developed for Global Expansion Tectonics prompts a need for a more thorough overhaul of the concepts of palaeomagnetics, in particular the conclusions drawn from the interpretations of pole positions, apparent polar wander paths, and displaced terranes.
Concluding Remarks
By considering the published Post-Jurassic oceanic magnetic isochron data of CGMW & UNESCO (1990), to constrain both plate configuration and palaeoradius with time, it was concluded that Global Expansion Tectonics provides a quantifiable "motor and mechanism" for Earth expansion. This has enabled the dynamic principles behind all major geologic phenomena to be resolved and readily explained. The success of this early research demonstrated an urgent need to extend modeling to the Precambrian, [currently in progress] and make this information available to industry. It was considered however that, because of the predictable hostility towards change, research should be structured towards demonstrating definitive auguments using modern, readily available, empirical data.
It is considered that an expanding Earth model will enable specialist researchers in fields such as palaeontology, palaeogeography, metallogeny, palaeomagnetics and so on to spatially display their global data on a worldwide, or continental scale as required. It is anticipated that all the specialist fields of geology can be confidently related spatially and temporally to a predictable process of Archaean crustal formation, Proterozoic crustal fragmentation, Proterozoic to Palaeozoic basin development, and Post-Jurassic plate motion history.
It is also considered, for geoscientific research to continue into the 21st Century, that we must be prepared to remove the "blinkers of dogma", so prevalent in our learned institutions, in order to encourage active research into alternatives too accepted geoscience.
