Rapid rotation of Fiji: Paleomagnetic evidence and tectonic implications

The timing and magnitude of rotation of Fiji in relation to the tectonic ev olution of the SW Pacific region has been investigated by extensive (126 si tes) paleomagnetic sampling of Late Miocene and younger units. Generally, s amples yielded well-defined characteristic remanence directions which indic ate that the main Fiji platform rotated by 135 +/- 17.5 degrees countercloc kwise commencing at, or before, 10 Ma. This very large and rapid rotation c eased abruptly at 3 Ma, coincident with the onset of spreading on the major N-S aligned spreading centers in the North Fiji Basin. Latest Miocene to P liocene paleomagnetic results indicate that Viti Levu, the main island itse lf, has suffered no internal disruption by localized rotations after 5 Ma. We present a reconstruction for the origin of Fiji which differs markedly f rom previous models such that Fiji, Tonga, and Lau form a continuous N-S al igned are and that are reversal was initiated at or near Fiji itself.