Foredeep tectonics and carbonate platform dynamics in the Huon Gulf, Papua New Guinea

Abstract

HAWAII MR1 side-scan sonar and six-channel seismic reflection data reveal a history of carbonate platform growth, drowning, and back stepping in the Huon Gulf, Papua New Guinea. This is one of the few modern sites where active carbonate platform development and foredeep subsidence are linked. 230 Th methods date aragonitic shallow-water corals, recovered from a modern depth of 2000 m, at 348 ؎ 10 ka. This documents rapid subsidence of the Huon Gulf in response to the encroaching Finisterre 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. Carbonate deposition has moved toward the foreland at an average rate of 110 mm/yr over the same period. Comparisons of the measured age with sea-level history (derived from the oxygen isotope record) suggest that the reefs may have formed during sea-level lowstands and drowned during rapid rates of sea-level rise.

Subsidence history, gravity anomalies, and flexure of the northeast Australian margin in Papua New Guinea

“…This sequence of events proved to be especially beneficial to carbonate production in the region by significantly increasing the thickness and width of the existing platform [Pigram et al, 1989]. A modern example of carbonate platform development coupled with foreland basin evolution exists in northern PNG [Galewsky et al, 1996] Resource Sciences (BRS), Canberra. Seismic data from the onshore part of the study area were not available for inclusion in the grid.…”

Drowned carbonate platforms in the Bismarck Sea, Papua New Guinea

“…Such platforms have been observed around the Hawaiian Islands (Moore and Campbell 1987;Grigg et al 2002), in the Solomon Sea, Papua New Guinea (Davies et al 1987a;Galewsky et al 1996;Webster et al 2004), in New Zealand (Stern and Holt 1994), and elsewhere. Subsidence in Hawaii was caused primarily by flexural volcanic loading (Campbell 1984), with the platforms tilting landward towards the locus of loading (Moore and Campbell 1987).…”

“…1). Davies et al (1987a), Galewsky et al (1996), and Webster et al (2004) described a series of submerged pinnacle carbonate platforms and drowned shallow-water reefs on the under-riding plate in the Huon Gulf. In MR1 sidescan imagery, the platforms appear as a sinuous line of high backscatter, which corresponds to the platform rim (Fig.…”

“…Subsidence in Hawaii was caused primarily by flexural volcanic loading (Campbell 1984), with the platforms tilting landward towards the locus of loading (Moore and Campbell 1987). In the Solomon Sea, however, subsidence was due to flexural loading of the subducting Australian plate by the overriding South Bismarck Plate, resulting in seaward tilting (Davies et al 1987b;Abbott et al 1994;Galewsky et al 1996;Galewsky 1998;Wallace et al 2004;Webster et al 2004). …”

Records of cosmogenic radionuclides 10Be, 26Al and 36Cl in corals: First studies on coral erosion rates and potential of dating very old corals

“…Modeling studies of reef accumulation as part of carbonate platform development during the Quaternary (Paulay and McEdward, 1990;Galewsky et al, 1996) rely on published coral erosion rates to estimate the balance between the effects of tectonics, sea level, and erosion on the morphology of reef terraces. Sea level studies aim to extract the sea level signal out of this balance.…”