. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography NATURE VOL. 235 FEBRUARY 4 1972 269 of the Cocos ridge was extruded. We offer the solution, therefore, that the angular geometry of the triple point has remained geometrically stable while it has migrated north- westward. If it were possible to show that the Cocos ridge, in its en- tirety, is constrained within the limits of the gore, this would mean that the triple point was bora at the Galapagos hot spot 40 bp. We suppose that this is probabl
. Collected reprints / Atlantic Oceanographic and Meteorological Laboratories [and] Pacific Oceanographic Laboratories. Oceanography NATURE VOL. 235 FEBRUARY 4 1972 269 of the Cocos ridge was extruded. We offer the solution, therefore, that the angular geometry of the triple point has remained geometrically stable while it has migrated north- westward. If it were possible to show that the Cocos ridge, in its en- tirety, is constrained within the limits of the gore, this would mean that the triple point was bora at the Galapagos hot spot 40 bp. We suppose that this is probably true, but it cannot be demonstrated because an unknown amount of north-westward extension of the Cocos ridge may have been subducted into the Middle America trench and thus not exist today. The Malpelo ridge just to the east of the Panama fracture zone might possibly be such a remnant of the Cocos ridge. Such an interpretation would necessitate an earlier extension of the Galapagos rift zone into that region that had become inactive, leaving this part of the ridge frozen on the Nazca plate. If this were the case then the early gore would have extended further east of the hot spot than west. The hot spot would then predate the triple junction. On the other hand, if the hot spot existed prior to the creation of the triple junction, an ancient and now isolated nematath should be present on the Pacific plate, on a bearing of 277° from the triple point and commencing where the Pacific is older than 40 We can find no evidence for such a nematath. This suggests that the hot spot and the triple point were born at the same Fig. 4 Development of Galapagos gore 10 bp. Dash-dot line represents Cocos and Nazca isochron flexures at that time; dotted line represents the Recent position of the flexures. Recent positions of Cocos and Carnegie ridges shaded. Arrows as in Fig. 2. Models Compared Van Andel el a/.8 have offered an alternative explanation for a portion of the Gal
Size: 1829px × 1366px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookcollectionamericana, bookleafnumber153
