Heat flow in the southwestern Pacific

One hundred and fifty-eight new heat-flow measurements in and around the marginal basins of the western Pacific are presented. Most of the measurements were collected in the Melanesian area and show that the region of high heat flow and shallow crustal elevation landward of the island arcs in the western Pacific includes the Fiji plateau and Lau basin. The high heat flow and shallow crustal depth of these two provinces can be accounted for by the recent intrusion of magma by a process similar to that at midocean ridges. The mean heat flow of the south Fiji basin, the Tasman abyssal plain, and the Coral Sea basin are below 1.5 μcal/cm2 sec, and the average depths of these provinces are greater than 4.5 km. These data are compatible with a simple sea-floor-spreading origin for these marginal basins if the process occurred more than 30 m.y. B.P.