Alyssa Peleo-Alampay

University of the Philippines System | UPD · National Institute of Geological Sciences

This study describes seasonal changes in the fluxes of planktonic foraminifera in response to changes in environmental conditions during the Asian Monsoon. Sediment trap systems were deployed for a period of 1 year at two locations in the Maldives: Kardiva Channel and Inner Sea. Twenty-six (26) planktonic foraminifera were recognized, of which six...

We reinvestigated the Pleistocene calcareous nannofossil biostratigraphy of Site U1431D (International Ocean Discovery Program (IODP) Expedition 349) in the South China Sea (SCS). Twelve calcareous nannofossil Pleistocene datums are identified in the site. The analysis confirms that the last occurrence (LO) of Calcidiscus macintyrei is below the fi...

Two nautilid (Cephalopoda, Mollusca) fossils are discovered from an exposure of the late Miocene – early Pliocene Calatagan Formation in Talim Point, Lian, Batangas, southwestern Luzon. They were identified as Nautilus sp. because of the similarity in conch shape and sutures to those of extant species of Nautilus. The two Nautilus specimens were fo...

We present a new calcareous nannofossil paleoproductivity reconstruction of the southeastern margin of the Sulu Sea to understand how marine productivity varied through time in one of the major fishing grounds of the Philippine archipelago. The study is based on two sediment cores obtained from two different hydrographic locations in the western eq...

Allen Phonolite is the proposed name for a newly discovered alkaline igneous rock complex in Allen, Northern Samar composed of phonolites and phonolite porphyries. Phenocrysts are made up of large crystals of analcime and diopside. The fine-grained groundmass is composed of K-feldspar, analcime, diopside, magnetite with magnetite and apatite as acc...

The work of SO-220 pursued a multidisciplinary approach. The continental shelf of the Gulf of Tonkin and its continental slope at the transition to the deep-sea areas in the South China Sea were surveyed by three teams from a biogeochemical (sub-project 1), physical oceanographic (sub-project 2) and coastal-marine geologic (sub-project 3) approach....

The South China Sea is the largest marginal basin in the world, and is located in the confluence of three major tectonic plates (Pacific-Philippine Sea, Indo-Australia, Eurasia). Its tectonic history and evolution throughout the Cenozoic has been the subject of much discussion with regards to its mechanism, timing, and relationship to neighboring g...

The paper presents the results of the calcareous nannofossil investigation of samples collected from known Cretaceous localities in Catanduanes Island, eastern Philippines. The study was conducted in order to verify and refine the ages of Yop and Codon Formations, the oldest lithostratigraphic units in the island. Based on the analysis of samples c...

Coring/logging data and physical property measurements from International Ocean Discovery Program Expedition 349 are integrated with, and correlated to, reflection seismic data to map seismic sequence boundaries and facies of the central basin and neighboring regions of the South China Sea. First-order sequence boundaries are interpreted, which are...

Combined analyses of deep tow magnetic anomalies and International Ocean Discovery Program Expedition 349 cores show that initial seafloor spreading started around 33 Ma in the northeastern South China Sea (SCS), but varied slightly by 1–2 Myr along the northern continent-ocean boundary (COB). A southward ridge jump of ∼20 km occurred around 23.6 M...

This poster characterizes the particle morphology of the andesitic and rhyolitic tephra deposits obtained from the cores in Sibuyan sea and Bohol sea, Philippines. The goal was to come up with the physical attributes of the two compositionally different tephra, which can be used in the interpretation of eruption style, fingerprinting and correlatio...

The South China Sea (SCS) provides an outstanding opportunity to better understand complex patterns of continental margin breakup and basin formation. The sea is situated at the junction of the Eurasian, Pacific, and Indo-Australian plates and is a critical site linking some of the major western Pacific tectonic units. Despite extensive studies, sa...

This study investigates the calcareous nannofossil assemblage and composition of 62 field samples collected from a calcareous sedimentary sequence exposed in Mamburao, Occidental Mindoro, Philippines. The sequence consisting of foraminifera-rich, alternating beds of mudstones and fine- to medium-grained sandstones was subjected to stratigraphic log...

This study investigates the calcareous nannofossil assemblage and composition of 62 field samples collected from a calcareous sedimentary sequence exposed in Mamburao, Occidental Mindoro, Philippines. The sequence consisting of foraminifera-rich, alternating beds of mudstones and fine- to medium-grained sandstones was subjected to stratigraphic log...

The Catbalogan Formation is a sequence of alternating beds of mudstones, sandstones and pebble conglomerates extensively distributed along the road from Rosario to Mondragon, and Catarman to Calbayog in Northern Samar. Most of the mudstones contain calcareous nannofossils while sandstones have benthic foraminifera, coal stringers and fragments of m...

Biri Island off Northern Samar is known for its impressive rock formations made up of sedimentary rocks, as well as volcanic flow deposits and agglomerates. Analysis of 55 mudstone to fine-grained sandstone samples collected from five localities around the island revealed poorly-to moderately-preserved calcareous nannofossils. Despite the lack of d...

Marine tephra layers in Philippine inland seas were studied to evaluate the history of explosive volcanism in the region and their impact on the marine environment. Two discrete andesitic (SiO*blc*2*elc* = 55-63 wt%) tephra layers were found at depths 446.5-448.4 cm and 454.9-455.8 cm in the gravity core MD 3057 recovered during the Marion Dufresne...

A detailed interbasinal study of calcareous nannofossils in surface sediments and their environmental preferences was conducted across the South China Sea, from the upwelling area off Vietnam to the non-upwelling area off Luzon, Philippines. Emiliania huxleyi, Florisphaera profunda and Gephyrocapsa oceanica are the dominant taxa in all the stations...

Alkenone unsaturation indices (Uk'37) of marine sediment could prove particularly useful on organic-rich continental margins where carbonate dissolution hampers the use of other paleoclimatic proxies [McCaffrey et al., 1990; Kennedy and Brassell, 1992]. Forty core top samples of Recent sediment from a latitudinal transect (23°-40°N) along the Calif...

A systematic study on the evolution and stratigraphic distribution of the species of Catinaster from several DSDP/ODP sites with magnetostratigraphic records is presented. The evolution of Catinaster from Discoaster is established by documentation of a transitional nannofossil species, Dicoaster transitus. Two new subspecies, Catinaster coalitus ex...

Alkenone unsaturation indices (Uk'37) of marine sediment could prove particularly useful on organic-rich continental margins where carbonate dissolution hampers the use of other paleoclimatic proxies [McCaffrey et al., 1990, doi:10.1016/0016-7037(90)90399-6; Kennedy and Brassell, 1992, doi:10.1016/0146-6380(92)90040-5]. Forty core top samples of Re...

The Cenozoic magnetobiochronology of Berggren et al. (1985a, b, c) has been essential in translating biostratigraphic information into numerical age information and widely used in studies of Cenozoic marine sediments. However, a significantly improved geomagnetic polarity time scale has recently been published (Cande and Kent, 1992) and the age dif...

The Plio/Pleistocene Laguna Formation consists in the Tres Hermanas area of tuffs deposited in an alluvial setting, with cycles of catastrophic deposition interrupted by periods when paleosol horizons formed that were intensively colonized by plants. Stegodon fossil remains consist of teeth, tusk and bone pieces belonging to at least 5 different an...

The Australasian microtektites, which are now generally accepted as the products of extraterrestrial impacts, occur near the Brunhes/Matuyama boundary at about 0.75 Ma and have a wide distribution ([approximately]10% of the earth's surface). This impact event is the second largest in the Cenozoic, and the impact crater has been estimated to be abou...