Sea-level rise and coral-reef development of Northwestern Luzon since 9.9 ka

Coral reef growth and relative sea-level record for the early mid-Holocene are established from three boreholes drilled on a raised Holocene reef at Currimao, northwestern Luzon, Philippines. Age control is provided by 230Th dates of 13 corals mostly in living position. The cores cover a depth interval from 3.8 m above to 26.7 m below present mean sea level (MSL) and consist of four lithofacies including (1) reef facies, (2) bioclastic facies, (3) clayey facies and (4) tuffaceous facies. The ages of dated corals vary from 6588 ± 27 ya at 1.4 m below MSL to 9855 ± 42 ya at 22 m below MSL. Results of this study indicate that the reef started growing about 9.9 ka when the minimum sea level, relative to the western Luzon coast, was about 27 m below MSL after tectonic correction. During 9.2–8.2 ka, reef accretion rate was as high as 10–13 m/ky. Coral reef developed to near paleo-sea level at about 6862 ± 28 ya and emerged due to tectonic uplift. The sea-level curve of Currimao is generally similar to that of the Western Australia coast but at least 8–11 m higher than that of Tahiti from 10 to 8.5 ka.