Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9535667 | Journal of Asian Earth Sciences | 2005 | 10 Pages |
Abstract
Subic Bay sediments and faults identified in seismic-reflection profiles were dated using sea-level curves. The oldest sedimentary packages are marine sediments subaerially exposed and eroded 20 ka. Fluvio-marine to wholly marine sediments were deposited during the ensuing transgression, and prograding units were deposited during stillstands or minor sea-level falls. Faults within the bay have three age ranges. The oldest set cuts through the pre-δ18O Stage 2 rock units, >18 ka; a second disrupts 10.2-11.3 ka sediments; and the youngest, which cut the uppermost sedimentary package, show that movements occurred about every 2 ky, most recently about 3 ka. Northwest-southeast faults that parallel onshore structures associated with Paleogene emplacement of the Zambales Ophiolite Complex to the west and north likely represent rejuvenated tectonism. The northern coastline and north-south-trending axial bay islands appear related to a lineament that dissects Mt Pinatubo farther northeast. A breach in the caldera of Mt Natib is the most likely source of a presumed pyroclastic deposit in the eastern bay that is associated with sediments about 11.3-18 ka, indicating that a Natib eruption occurred much more recently than previously documented for this volcano.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Geology
Authors
Ma. Edweena Joan A. Cabato, Kelvin S. Rodolfo, Fernando P. Siringan,