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the Mid-Atlantic Ridge (Original)

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Carolyn Silver
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« Reply #60 on: July 28, 2008, 11:38:59 pm »


Figure 7. Cross-sections across the Peru-Chile trench (left) and Bonin-Honshu arc (right), showing earthquake centers. (Reprinted with permission from Benioff [10]. Copyright by the Geological Society of America.)

    Plate tectonicists insist that the volume of crust generated at midocean ridges is equaled by the volume subducted. But whereas 80,000 km of midocean ridges are supposedly producing new crust, only 30,500 km of trenches exist. Even if we add the 9000 km of 'collision zones', the figure is still only half that of the 'spreading centers'. With two minor exceptions, Benioff zones are absent from the margins of the Atlantic, Indian, Arctic, and Southern Oceans. Africa is allegedly being converged on by plates spreading from the east, south, and west, yet it exhibits no evidence whatsoever for the existence of subduction zones or newly forming mountains belts. Antarctica, too, is almost entirely surrounded by alleged 'spreading' ridges without any corresponding subduction zones, but fails to show any signs of being crushed. It has been suggested that Africa and Antarctica may remain stationary while the surrounding ridge system migrates away from them, but this would require the ridge marking the 'plate boundary' between Africa and Antarctica to move in opposite directions simultaneously!
    If up to 13,000 kilometers of lithosphere had really been subducted in circum-Pacific deep-sea trenches, vast amounts of oceanic sediments should have been scraped off the ocean floor and piled up against the landward margin of the trenches. However, sediments in the trenches are generally not present in the volumes required, nor do they display the expected degree of deformation. Scholl & Marlow, who support plate tectonics, admitted to being 'genuinely perplexed as to why evidence for subduction or offscraping of trench deposits is not glaringly apparent' [11]. Plate tectonicists have had to resort to the highly dubious notion that unconsolidated deep-ocean sediments can slide smoothly into a Benioff zone without leaving any significant trace. Subduction along Pacific trenches is also refuted by the fact that the Benioff zone often lies 80 to 150 km landward from the trench; by the evidence that Precambrian continental structures continue into the ocean floor; and by the evidence for submerged continental crust under the northwestern and southeastern Pacific, where there are now deep abyssal plains and trenches.
    An alternative view of Benioff zones is that they are very ancient contraction fractures produced by the cooling of the earth. The fact that the upper part of the Benioff zones dips at less than 45° and the lower part at more than 45° suggests that the lithosphere is under compression and the lower mantle under tension. Since a contracting sphere tends to fracture along great circles, this would account for the fact that both the circum-Pacific seismotectonic belt and the Alpine-Himalayan (Tethyan) belt* lie on approximate circles.


*The Alpine-Himalayan belt stretches from the Mediterranean to the Pacific, and is also visible in Central America. Some earth scientists believe it was once global in extent. Blavatsky says that the Himalayan belt does indeed encircle the globe, either under the water or above (The Secret Doctrine, 2:401fn).



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