HR: 1340h
AN: U13A-0866    [Abstracts]
TI: Global Reconstruction of Plate Boundaries: 0 to 55 Ma in the Indo-Atlantic Hotspot Frame of Reference
AU: * Rowley, D B
EM: drowley@uchicago.edu
AB: Plate kinematic constraints are integrated into a near global model of the first-order plates, as well as many smaller crustal and lithospheric fragments that serve as the basis for a new set of plate boundary distribution maps as a function of time. At present the maps extend back to 55 Ma. The maps employ an Indo-Atlantic hotspot frame of reference of Müller et al. (1993) that is not statistically different from a mean paleomagnetic frame of reference derived from the major, relatively undeformed, continents over this interval of time. Total reconsruction poles and estimated approximately instantaneous (3 m.a. averages) poles provide the kinematic foundations of this new set of plate boundary maps. The underlying kinematic motions are consistent over 83 Ma with limited variations in mean global half spreading rate at 26.5 plus/minus 4.2 mm/a, with a significant fraction of this variation occurring between C13 (approx. 33.06 Ma) and C6 (approx. 20.13 Ma) reflecting increased rate of Nazca-Pacific divergence. The is no simple secular trend evident in global half spreading rates, as has been inferred in the past. An interesting aspect of these reconstructions is variation in rate of plate boundary migration in this frame of reference. These variations imply potentially deeper mantle buoyancy controls on certain boundaries, and may allow independent identification of active versus passive segments of the mid- oceanic ridge system.
DE: 8150 Plate boundary: general (3040)
DE: 8155 Plate motions: general (3040)
DE: 8157 Plate motions: past (3040)
SC: Union [U]
MN: 2007 Fall Meeting