Title: HIGH-RESOLUTION BATHYMETRY IN SELECT PHILIPPINE REEFS AND THEIR IMPLICATIONS ON THE LATE PLEISTOCENE-HOLOCENE SEA-LEVEL CHANGES AND REEF DEVELOPMENT

Abstract: Coral reefs provide an effective archive to past sea levels because reef-forming corals grow at a limited depth range and have a good geologic preservation. High-resolution multibeam bathymetry to a depth of 70m show a series of terraces and steep scarps in Apo Reef, Occidental Mindoro; Masinloc, Zambales; and Patnanungan, Quezon in the Philippines. Diver and drop-camera observations indicate the proliferation mesophotic corals especially along the edges of terraces. The terraces are interpreted to represent reef flat to reef crest environments and scarps as reef fronts. These are possibly the back-stepping reefs that were drowned during the overall rise of sea level. Mounds with reliefs of 2-10 m along the edges of terraces in Apo Reef and Patnanungan may represent catch-up growth. This may have been made possible by a deeper photic limit, greater depth range of coral assemblage and relative protection from wave action in the sites. Comparison of the distribution of the depths of the terraces across reefs shows clustering in three depth ranges which may correspond to three sea-level stillstands in the past 12-14 ky in the South East Asia. Variations in depth and number of terraces may indicate local tectonic influence. This provides an opportunity to extend the sea level record in the Philippines towards the Late Pleistocene.

Authors: Munar JC, Siringan FP, Manalaysay D, Candelaria E, Cabactulan D, Calleja M, Villanueva R, Cabaitan P, Villanoy C

Presentation: Poster (#400)

Session: 35

Date: 06/22/16

Time: 18:15 - 19:45

Location: Poster/Exhibit Hall

Back