FOREDEEP TECTONICS AND CARBONATE PLATFORM DYNAMICS IN THE HUON GULF, PAPUA-NEW-GUINEA

HAWAII MR1 side-scan sonar and six-channel seismic reflection data rev eal a history of carbonate platform growth, drowning, and back steppin g in the Huon Gulf, Papua New Guinea, This is one of the few modern si tes where active carbonate platform development and foredeep subsidenc e are linked. Th-230 methods date aragonitic shallow-water corals, rec overed from a modern depth of 2000 m, at 348 +/- 10 ka. This documents rapid subsidence of the Huon Gulf in response to the encroaching Fini sterre Mountains at an average rate of 5.7 mm/yr for the past 348 k.y. , the highest subsidence rate reported from any foredeep setting, Carb onate deposition has moved toward the foreland at an average rate of 1 10 mm/yr over the same period. Comparisons of the measured age with se a-level history (derived from the oxygen isotope record) suggest that the reefs may have formed during sea-level lowstands and drowned durin g rapid rates of sea-level rise.