Concluding Remarks on the Theory of Global Strike-Slip Tectonics

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The theory of Global Strike-Slip Tectonics is providing an alternative approach to global plate tectonics, in which internal deformation of plates is put forth of boundary processes. Strike-slip faults are considered being of primary importance in deciphering the structural geology of crustal fragments, while normal faulting and thrusting are only complimentary elements of plate-interior kinematics.

The classic plate tectonic framework commonly fails to explain the interaction of low hierarchy crustal fragments; as a consequence several inefficient regional tectonic models were generated, which have created confusion and paradox situations. Albeit, we have presented a few of such conflicting situations, particularly from the Mediterranean Basin, the scope of the present study did not permit to give an extensive worldwide review. That can be made, however, in the forthcoming issues of the JGSST journal, with your kindly contribution.

Relying on the aforementioned inadequate plate tectonic models, mysteries have propagated further into the domain of sedimentary geology as well, e.g. the origin of the Messinian Salinity Crisis also remained unrevealed, or basin modelling efforts failed to reproduce observed basin infill geometries.

For hydrocarbon and ore exploration, plate scale events are too large to deduce a consistent local scale model. Therefore, we have looked after the behavior of smaller scale tectonic units.

While approximating with a holistic approach and integrating several data types, as described in previous sections, we have discovered that established global plates can be broken down into low hierarchy crustal fragments, like nanoplates and pikoplates. These latter already can be readily used in the delineation of prospective trends and play assessment.

The concept of stress nodes was introduced to describe the spatial clustering of earthquake epicenters, while the concept of extension nodes is localizing and gives explanation to regions of intraplate magmatism, all related to aspects of the regional stress fields.

We have emphasized the importance of simple shear stress fields in providing space management solutions for the low hierarchy crustal fragment interactions. Beyond that pikoplates and nanoplates are kinematically integrated into microplates, we have found that all these low hierarchy elements are commonly integrated into kinematic chains, which can be made up of various oceanic and continental crustal fragments, occasionally linked by inactive rift segments. They are usually showing lateral kinematic constraints from the behalf of other kinematic chains, orchestrated by the Coriolis force.

Like trains, kinematic chains perform a constant eastward drift towards their backstop, identified in the Jade Dragon – Smith Mp – Sunda Arc lineament. Behind this backstop lineament, crustal fragments are intensively deformed and broken into small and arcuate units. In this area, as suggested by earthquake clustering and a P-wave tomographic profile from northeastern Japan, crustal fragments are rather performing strike-slip overriding along steep master faults, than real subduction, and the same might apply for the Western Pacific ‘subduction’ zone. True subduction, where oceanic plate is recycled into the asthenosphere may only happen along the western margin of the American continents. When contractional space problem occurs, oceanic crustal fragments either perform lateral duplexing like in the case of the Marquesas, Bismarck and Caribbean nanoplates, or may even override each-other, forming oceanic ridges (e.g. Laximi Ridge). Space problem in the continental domain is resolved in the similar way, by incipient various scale lateral duplexing, than vertical duplexing. Initial push-up ranges (proto-orogens) may advance into evolved orogens, like in the case of the Atlas Mountains, as proven by Ellero.

Herein, we have proposed the extension of Ellero’s model to the whole Tethys area, and gave a new definition for orogenesis, in the GSST approach.

In addition to the review of the orogenesis and subduction concept, we have drawn preliminary conclusions about the East African Rift strain patterns, as well. Selecting random rift zones from published articles through the East African Rift area, strike-slip tectonics related faulting and deformation is as common as elsewhere in the world; however the magnitude of fault-displacements seems less expressed. Here, the role of tension fracture components is more relevant, and these continental rifts are interpreted as microplate scale tension fractures. Because crustal thickness is much larger than elsewhere, structural deformation is slow, but still present along deep crustal faults, which either give birth to intraplate volcanism, or possibly produce punctual release of high-pressure mantle volatiles, as we have discussed in the impact crater related section.

Acknowledgements

We are grateful for NASA (SRTM), European Mediterranean Seismological Centre (earthquake database), Max Planck Institute of Geochemistry Mainz (Georoc database), Google Earth, UNAVCO (GPS measurments) for sharing their database over the internet. ADX Energy (Perth) is thanked for providing a close seismic study opportunity on the onshore and offshore geology of Tunis.