Holocene Relative Sea-level Fluctuations Recorded in Tidal Notches along the Pacific Coast of Northern Luzon, Philippines

Abstract

 Relative sea-level data of the Philippines can be used to reconstruct global sea-level histories because isostatic influences from the melting of gigantic ice fields formerly located on both North American and European continents during the last glacial age are not significant. Ages and elevations of tidal notches are mapped along the northern coast of the Luzon Island, Philippines, and the results indicate that sea level during the Holocene was punctuated by discrete sea-level high stands. The first high stand occurred between 7.5-6.0 ky BP when sea level reached of 1 m above the present mean low tide level (pmlt). This was followed at a second rise of sea level reaching from 1.8 m to 2.7 m above pmlt from 6.0 to 4.0 ky BP. A descending trend of sea-level was then observed and stayed at a level from 0.9 to 1.2 m above pmlt between 2.8 and 1.2 ky BP. Although the magnitudes of these Holocene high stands differ depending on the locations of Luzon Island due to tectonic histories, observed 3 Holocene high stands have been widely reported around the Philippines. Given that three sea level high stands during the Holocene have been found with similar timings in Japan, Vietnam, and Australia, they seems to represent global climate signals.