CompuServe Messages

Doug >> As stated before, I am aware of no motions that require a dramatic amount of plate compression to fit through a narrow "exit". In the Indonesian case we are talking about different subducting plates approaching from different directions – each plate is traveling in a mostly unified direction as far as I can tell.<< I agree that a unified motion is what is stated but you cannot have a unified motion into and out of a large arc. Motion to the inside necessitates reduction of the size and motion to the outside of the arc needs thinning expansion or fracturing radially. >>Those faults are lined up well for India's sprint, though it is farther out to sea at the Carlsberg ridge where this is really expected.<< This is what I was pointing out. Another of earths head scratchers. Madagascar was north of its present position (relative to Africa), in what is now the Somali basin.<< I put it there at first but now have it south at the next inset in one simulation and north in the gap at the top of the horn of africa. I hope to settle this within a few more weeks. >>As near as I can tell, Africa hit Europe and raised the Alps, Carpathians and Caucasus Mts. before India was halfway to Asia.<< I agree…I see the mediterranean as a rift that split europe from asia and Greenland from North America before the Atlantic split apart. Then after the atlantic split africa was forced Northward and jammed Europe. >> When the transform faults are relatively long and the spreading ridge segments are short, the feature as a multi-segment whole seems to trend more in the direction of the faults. But the spreading is along the faults, generally perpendicular to the individual spreading segments.<< Yes I agree..if I understand the point. The width of the South West Indian Ridge is measured in a SW to NE direction. It is similar in age as the South East Ridge where it connects to but it has spread along the transform fault at a much more rapid rate showing the sprint of India as you say. >>This also means if you look again, you may figure as I do that the Carlsberg, central, and southeast Indian ridges are all spreading in nearly the same direction.<< Only where the transform faults are parallel. Again when you take any plate and using the shift or transform faults as the key to motion which we have both agreed to you come up against the big problem for plate motion. The shift faults point in multiple directions all on the same plate with the same unified motions. Look at Antarctica for a clear example of what my observation states. The motions in some places are 90 degrees to the observed shift faults. This can't be so if the basins are forming over time. Kamron