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dc.contributor.authorJaraula, Caroline
dc.contributor.authorSiringan, F.
dc.contributor.authorKlingel, R.
dc.contributor.authorSato, H.
dc.contributor.authorYokoyama, Y.
dc.identifier.citationJaraula, C. and Siringan, F. and Klingel, R. and Sato, H. and Yokoyama, Y. 2014. Records and causes of Holocene salinity shifts in Laguna de Bay, Philippines. Quaternary International. 349: pp. 207-220.

A 7000-year record of salinity shifts from molluscan and diatom assemblages and verified geochemical salinity proxies (C/S, S, Sr, Ca, and Sr/Ba) is reconstructed from Philippines' largest freshwater lake Laguna de Bay. The salinity shifts are interplays of millennial-scale sea level change, centennial-scale tectonic activity from the West Marikina Valley Fault (WMVF) and decadal-scale climatic changes. Currently only 1 m above mean sea level, the lake is connected to Manila Bay through the Pasig-Napindan River, which meanders across a densely populated “Parañaque Strip” partly occupied by metropolitan Manila. The controversial WMVF borders the lake on its western shore. Our 10.5 m sediment core from the western lobe reveal that the deposits are from a marine environment deposited 6600 cal BP to 4700 cal BP during a sea level still stand above present mean sea level (apmsl) in Southeast Asia and the Philippines. Episodic decreases in salinity with 260 y cycles were traced to the activity of the WMVF that would have accounted for at least 6 m of uplift of the Parañaque Strip. The vertical component of movement raised a sill and emergent landmass that started to isolate the Paleo-Laguna de Bay from Manila Bay. Subsequent episodic uplifts and sea level fall decreased depths to intertidal levels by 4700 cal BP, salinity to brackish but highly-influenced by marine waters by 4100 cal BP and to freshwater by 3100 cal BP. The latest salinity increase since mid-1960 is attributed to renewed saltwater incursion due to abnormally dry years, low lake levels, and Pasig River delta plain subsidence.

dc.publisherPergamon-Elsevier Science Ltd
dc.subjectCoastal lakes
dc.subjectHolocene sea level
dc.subjectMarikina Valley fault
dc.subjectSalinity proxy records
dc.titleRecords and causes of Holocene salinity shifts in Laguna de Bay, Philippines
dc.typeJournal Article
dcterms.source.titleQuaternary International
curtin.departmentDepartment of Chemistry
curtin.accessStatusFulltext not available

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