Overthrusting and Subduction
Overthrusting and Subduction
| "... It is concluded that overthrusting is a far more important tectonic mechanism than subduction. It follows that Plate Tectonics theory needs to be re-examined." |
OVERTHRUSTING AND SUBDUCTIONAndrew Kugler,
AEG Energy, Texas, USAIt has long been held that it is impossible to distinguish overthrusting from underthrusting. Indeed, it has been argued that these are simply relative terms, and distinction is not warranted. The thesis presented here is that it is possible to distinguish overthrusting from underthrusting in map view, when thin sheets that have a proportionately great area relative to thickness are involved. It is possible as well to distinguish the active, moving sheet from the passive, resisting and surrounding mass.The tearing margins, which develop to separate the deformed sheet from the resisting mass, allow these distinctions. This is important because the major plates and the great sedimentary foldbelts of the Earth’s surface, which are said to mark (or, have marked) the convergent boundaries of these plates, fall into the category of thin sheet deformation. All of the major ocean basins are floored by oceanic crust of mid-Jurassic or younger age. Fundamental to Plate Tectonics theory is the proposition that the pre-middle Jurassic crust, which previously occupied the space now occupied by today’s oceanic crust, have disappeared at convergent plate boundaries. Underthrusting, or subduction, at these boundaries is held to be the mechanism whereby that occurred. Several specific regions of the globe are analysed in n effort to identify and distinguish areas of subduction and areas of overthrusting. On a global scale, areas of subduction are extremely limited while areas of overthrusting are both numerous and widespread. It is concluded that overthrusting is a far more important tectonic mechanism than subduction. It follows that Plate Tectonics theory needs to be re-examined.
17AGC Abstracts 2003
(posted here 10 april 2005)
(...note the interesting variant in the last two sentences from another posting, highlighting growing awareness of torsion and extension)
....from areas of overthrusting. It is concluded that overthrusting, torsion and tensional separation are more recognizable, more widespread and more important tectonic mechanisms than subduction. It follows that subduction, as a basic tenet of “Plate Tectonic Theory”, perhaps needs to be re-examined.
3-D Visualization of Structural Styles
2003 AAPG International Conference & Exhibition Technical Program