Monday, November 30, 2009
Equatorial Bulge Termination and shear at 40N or 41S Latitudes
Although the Equatorial Bulge is presumably due to the Elliptical shape of the Earth (due to centrifugal force slinging out the middle portion), the Google Earth photos and analyses show that the termination of the bulge is sharp and confined to about 1-2 degrees of Latitude. There is drastic shear developed along the 40th parallel, as evidenced by sudden changes in geography and subsurface features:
Nevertheless, at the Mendocino transform- which shears westward on the NORTH side, as seen by the shove to the west of the HI-EMPEROR SEAMOUNT chain, there is a rift near the continental slope which shears eastward until reaching the Cascade Mountains.
In the southern hemisphere, EB apparently occurs at 41S, but the error in interpretation is about 1 degree Latitude, so this can be ignored. New Zealand is sheared North from South Island at the 40S latitude- similarly to Tasmania from Australia- yielding confirmation that shear occurs in this part of the Globe.
There are few locations on land in the southern Hemisphere to check further, and the shear lines in the ocean basins are scanty for E-W transforms, in the Southern Hemisphere. Back to North America, there is shear or displacement shown in the Appalachian Mountains (see the inflection in the SW-NE display) and at the southern edge of Long Island- both of which are along the 40N parallel:
The tentative CONCLUSION is that EB is not a gradually-changing surface (or smoothly decreasing ellipse to the north); rather it displays the characteristics of a HUMP. The Bulge must have an abrupt transition to the spherical or elliptical surface at the 40N latitude. Several geological features augment this supposition: The Yellowstone track at a locus near 40 N, and the Overthrust belt. Below is shown Turkey, which is very similar in many respects to the B&R and CP couplet just south of 40N:
The South American coast shows some influence of the shear between EB and the domain further south, mainly at portions of the east coast. In the west, the region is under extension- west of the Andes- and forms islands:
40N or 40S EB boundary shear shifts direction at Coastal or Continental Shelves
Oceanic transforms or shear lines are regular for ocean basins, except for meteoric strikes and shifting of the Polar Axis- such as for the KT disruption. Continents portray rotating Coriolis cells, and do not show lengthy linear shear zones; rather they exhibit rotations of various diameters, according to the type of feature instrumental in creating them. Regional linears, such as the Hurricane fault Hf, have regional cells of diameters smaller than the fault zone, and continental features- such as the Mississippi River New Madrid fault zone- exhibit cell diameters on the order of sizes of states.
Generally, this EBD (diminution) shear displaces geological features to the west, South of 40N latitude. This display continues into the Pacific Ocean, with the subsequent intermission of rifts and shear reversals for the shelves. This exhibits rotation of what were called Mini-Plates, which were assumed to break off from the dominant Pacific plate. This was a “nice touch”, but the terranes assumed to form by colliding with the continents were unknown as to source and incoming orientation. With the Coriolis rotation, the incipience is simple; the Mini-Plate merely rotates from the continent along the coast line. In the process, local rifts and transforms are created. This explains why there is reversal of the general shearing due to the faster movement of the Crust north of 40N. West of the local rifts, the shear is again westward north of 40N latitude, but evidently much different than that below 40N. There is one other part of the puzzle, however, and that is the gradual southward shift of the 40N transform to about 31S with approach to the HI-E seamount chain. Again, the transform is rotated gradually to the south CCW), and fits with the Coriolis theory. The question remaining is: Is this large curvature, on the order of continental size, due to Crustal movements or is the Mantle involved?
We will try to solve this problem, by looking at progressively larger cells- starting with local ones, such as the Grass Valley cell with a diameter of about 30 km. We will also attempt to discern why the Southern hemisphere presents very little to confirm the shearing of the Non-Bulge from the part near the Equator undergoing diminution. It is shown on the SA eastern coast, with breakup into islands on the west coast. This all indicates extension for Chile, below the 40S Latitude, where the Plate Tectonics theory would have only compression and subduction in that region (due to the presence of andesitic vulcanism). Altogether, it seems that upon closer inspection, the Plate Tectonics idea applies only to the deep ocean basins and that it only provides a start in understanding the movements of the Crust. Wherever there is a landmass (even islands), there is rotation induced by Coriolis Force and the subduction-wandering of continents idea does not apply.