Mateo, Z.R.P. and Siringan, F.P., 2016. Morphological and sedimentological signatures of Late Holocene prodelta lobes in Lingayen Gulf, Philippines.

Delta switching is an integral part of coastal evolution and may be caused by a combination of autogenic and allogenic factors. We present offshore signatures of modern and ancient prodelta deposits that document delta switching in the bayhead region of Lingayen Gulf, NW Philippines. Prodelta lobes of prograding systems are marked by areas of shoaling of about 6 m within 95 years, with around 30% clay, whereas abandoned deltas are manifested as areas of deepening of around 3 m with as much as 80% sand. The sorting and kurtosis of the mud fraction further categorize recent and current sedimentary environments and processes such as erosional and shoreface environments and areas dominated by sediment plume and normal offshore deposition. High-resolution subbottom profiles reveal the stacked and truncated nature of different prodelta lobes associated with the latest four tectonically induced delta-switching events. This documented succession of well-preserved deltaic units in a semienclosed basin illustrates the sensitivity of tropical coastal sedimentary environments to autogenic and allogenic factors such as tectonism, sea-level, and monsoonal climate changes.