The onset of independent Bellingshausen plate movement in the SouthPacific is estimated at just after anomaly C33o. This event is related to achange in the offset sense on the transform arm of the late CretaceousPacific-Phoenix-Antarctic triple junction which caused the Pacific-Antarcticridge between the Antipodes fracture zone and the triple junction to rotateclockwise so that its northern end could stay near the triple junction. Thisrotation necessitated the creation of transform faults on the Udintsev, Tharp,Heezen and V transforms by different mechanisms. At anomaly C27, theBellingshausen plate ceased to move independently and the Pacific-Antarctic Ridge inherited the set of long offset transforms. Shortlyafterwards, much of the ridge displays evidence for a spreading ratedeceleration, possibly related to transpression on the long-offset transforms.We speculate on a link between these events and regional tectonicchanges at anomaly C27.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > MAR2-Palaeo Climate Mechanisms and Variability