Carlo Arcilla

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

Recent studies suggest the existence of two ophiolites in Palawan Island: the Central Palawan Ophiolite (CPO) and the Southern Palawan Ophiolite (SPO). New geochemical data in this study from the volcanic rocks of the Palawan ophiolites further support this interpretation. The CPO lavas have back-arc basin basalt (BABB) affinities with LILE enrichm...

Ultramafic rocks are considered as the most important geogenic sources of Cr whose hexavalent species is of environmental concern. In tropical to subtropical areas (e.g. New Caledonia, Brazil, Philippines), prolonged and pervasive weathering of ultramafic rocks produces Ni laterite ores which are further enriched in Cr. While elevated levels of Cr...

The Intex laterite deposit in Mindoro, Philippines is derived from the weathering of the ultramafic rocks under a tropical climate. This study investigates the several types of serpentines and the effect of the degree of chemical weathering of ultramafic rocks and laterites on the enrichment of Ni in the deposit. The five types of serpentines are d...

Strength and durability of concrete largely depend on the composition, mineralogy and chemical characteristics of raw materials. These materials include aggregates, Portland cement, supplementary cementitious materials and chemical admixtures. Precise evaluation of their individual impact to the overall strength and durability of concrete is vital...

Concrete petrography is a vital tool in ensuring the quality and safety of concrete structures around the world. In the Philippines, this method has long been known but only lately became available and feasible for use by the government and industry at large. Testing of construction materials in the country have been limited to physical strength te...

Weathering in ophiolitic exposure settings often produces fluids and sediments that have elevated concentrations of various toxic heavy metals such as chromium, nickel, cobalt, copper, and zinc. Microorganisms inhabiting these environments (e.g., serpentinite soils or sediments) are likely adapted to tolerate these metals along with other physicoch...

Springs hosted in ophiolites are often affected by serpentinization processes. The characteristically low DIC and high CH4 and H2 gas concentrations of serpentinizing ecosystems have led to interest in hydrogen based metabolisms in these subsurface biomes. However, a true subsurface signature can be difficult to identify in surface expressions such...

We present the results of a study of reduced gas seepages associated to serpentinized ultrabasic rocks in the ophiolitic complexes of Oman, the Philippines, Turkey and New Caledonia. These gas seepages are made of mixtures of 3 main components which are H 2 , CH 4 and N 2 in various proportions. The relative contents of these 3 gas show 4 distinct...

Palawan Ophiolite is a Cretaceous, dismembered ophiolitic terrane stretching 320-kilometers from Central to South Palawan, Philippines. It is composed of mantle peridotites, gabbros, and volcanic rocks with associated sedimentary units. At present, it is assumed that this ophiolite has a supra-subduction zone (SSZ) signature. However, recent findin...

Palawan Continental Block (PCB) is a continental unit separated from the rest of Eurasia due to the opening of the South China Sea in the Oligocene. It collided with the rest of the Philippine Mobile Belt during the Middle Miocene. Located to the east of Palawan Continental Block, Cuyo Islands is an archipelago of about 50 volcanic islands in Sulu...

Terrestrial serpentinizing systems harbor microbial subsurface life. Passive or active microbially mediated iron transformations at alkaline conditions in deep biosphere serpentinizing ecosystems are understudied. We explore these processes in the Zambales (Philippines) and Coast Range (CA, USA) ophiolites, and associated surface ecosystems by prob...

This paper proposes a comparative study of reduced gas seepages occurring in ultrabasic to basic rocks outcropping in ophiolitic complexes based on the study of seepages from Oman, the Philippines, Turkey and New Caledonia. This study is based on analyses of the gas chemical composition, noble gases contents, stable isotopes of carbon, hydrogen and...

The occurrence of flooding is already a common phenomenon in the Philippines where numerous tropical cyclones pass annually. The study is focused on flood hazards in Angono River Watershed in Rizal, Philippines which has historically experienced significant flooding events. Local residents believe that the open-pit quarrying activities in the area...

Black sand mining is rampant in the Philippines. However, knowledge about the minerals comprising the black sands is virtually nil. These sands are exported as magnetite concentrate, but this has to be shown by quantitative studies to determine other valuable elements associated with them. This study aims to determine the kind and quantity of heavy...

Black Sand mining is rampant in the Philippines. However, knowledge about the minerals comprising the black sands is virtually nil. These sands are exported as magnetite concentrate, but this has to be shown by quantitative studies to determine other valuable elements associated with them. This study aims to determine the kind and quantity of heavy...

The Palawan Ophiolite in Southern Palawan describes the three formations (Beaufort Ultramafic Complex, Stavely Gabbro, and Espina Formation) which correspond to an ophiolite sequence. Several studies, e.g. Pena (2008), Wolfart et al (1986), and Tumanda et al (1995) reveal that the Palawan Ophiolite is of Late Cretaceous age. The weathered portion o...

In the Zambales ophiolite range, terrestrial serpentinizing fluid seeps host diverse microbial assemblages. The fluids fall within the profile of Ca²⁺-OH⁻-type waters, indicative of active serpentinization, and are low in dissolved inorganic carbon (DIC) (<0.5 ppm). Influx of atmospheric carbon dioxide (CO2) affects the solubility of calcium carbon...

A field campaign targeting high pH, H2-, and CH4-emitting serpentinite-associated springs in the Zambales and Palawan Ophiolites of the Philippines was conducted in 2012-2013, and enabled description of several springs sourced in altered pillow basalts, gabbros, and peridotites. We combine field observations of pH, temperature, conductivity, dissol...

Exiguobacterium sp. AB2 is a haloalkaliphilic bacterium isolated from a hyperalkaline spring in Manleluag, Pangasinan, Philippines. Sequencing of bacterial DNA assembled a 2.85 MB draft genome. Analysis suggests the presence of genes for tolerance to stresses such as elevated pH and salt concentrations and toxic metals.

Exiguobacterium sp. AB2 is a haloalkaliphilic bacterium isolated from a hyperalkaline spring in Manleluag, Pangasinan, Philip-pines. Sequencing of bacterial DNA assembled a 2.85 MB draft genome. Analysis suggests the presence of genes for tolerance to stresses such as elevated pH and salt concentrations and toxic metals.

CO"2 capture and storage (CCS) is widely regarded as an important low-carbon technology for reducing greenhouse gas emissions from large industrial point sources. It entails the capture of a relatively pure CO"2 from exhaust gases using different techniques, and then storing this captured gas in various geological sinks. Large-scale deployment of C...

The microbial diversity was investigated in sediments of six acidic to circumneutral hot springs (Temperature: 60-92°C, pH 3.72-6.58) in the Philippines using an integrated approach that included geochemistry and 16S rRNA gene pyrosequencing. Both bacterial and archaeal abundances were lower in high-temperature springs than in moderate-temperature...

The occurrence of Cretaceous calcareous nannofossils is reported from the limestone units of Codon Formation in Codon Point, San Andres, Catanduanes. The nannofossil assemblage consists of long ranging taxa like Watznaueria spp. (W. barnesiae, W. fossacincta and W. manivitiae) and Late Cretaceous forms including Micula prinsii, Micula praemurus, Mi...

We have examined a number of hyperalkaline (pH 9-12) springs situated in ophiolites in various locations in the Philippines (Pangasinan, Zambales, Palawan). These clearly result from interactions of groundwater with mafic minerals, but differences in major- and trace-element compositions suggest complex reactions that need further study. Such sprin...

The potential of using ophiolites for CCS has been pointed out before, but no case study has been conducted for the Philippines. Here, the potential for CCS in both ophiolites in general and ophiolites in the Philippines in particular is examined and discussed. Specific drawbacks of using ophiolites as a CO2 sink are presented for the first time, u...

We investigated rates of chemical weathering of volcanic and ophiolitic rocks on Luzon Island, the Philippines. Luzon has a tropical climate and is volcanically and tectonically very active, all factors that should enhance chemical weathering. Seventy-five rivers and streams (10 draining ophiolites, 65 draining volcanic bedrock) and two volcanic ho...

Bentonite is one of the safety-critical components of the engineered barrier system for the disposal concepts developed for many types of radioactive waste. However, bentonite — especially the swelling clay component that contributes to its essential barrier functions — is unstable at high pH. To date, results from laboratory tests on bentonite deg...

We compare the geological environments of sites of emission of natural hydrogen in the Oman ophiolite and the Zambales ophiolite (Luzon, Philippines). The genesis of natural H2 results from the interaction between ultrabasic rocks and aqueous solutions circulating in deep fracture networks, by oxidation of metals (Fe2+, Mn2+) and reduction of water...

Key words: bentonite/hyperalkaline cement leachate interaction, low alkali cement, natural analogue 1. Introduction Bentonite is one of the most safety-critical components of the engineered barrier system in the disposal concepts developed for many types of radioactive waste. The choice of bentonite results from its favourable properties (including...

Bentonite plays a significant barrier role in many radioactive waste repository designs, where it has been chosen due to its favourable properties such as plasticity, swelling capacity, colloid filtration, low hydraulic conductivity and its stability in relevant geological environments. However, bentonite is unstable at high pH meaning that it coul...

Silicic volcanic deposits (>65wt% SiO2), which occur as domes, lavas and pyroclastic deposits, are relatively abundant in the Macolod Corridor, SW Luzon, Philippines. At Makiling stratovolcano, silicic domes occur along the margins of the volcano and are chemically similar to the silicic lavas that comprise part of the volcano. Pyroclastic flows ar...

The Laguna de Bay Caldera is a depression 200 km2 in diameter that occurs within the Macolod Corridor. The Macalod corridor is a NE-SW zone of rifting through the central part of Luzon that was the site of extensive Pliestocene to Holocene volcanism, including major pyroclastic eruptions from the Laguna de Bay Caldera. This caldera has erupted larg...

Silicic magmatism occurs in the Macolod Corridor, Luzon Island, Philippines. Luzon Island is an oceanic arc related to the subduction of the South China Sea plate eastward under the Philippine. Several silicic domes and voluminous pyroclastic deposits occur in the Macolod Corridor, which is a pull-apart rift zone that cuts across Central Luzon. The...

High field strength element (HFSE) enrichment, rare in normally HFSE-depleted arc lavas, has been documented in southern Philippine arc. Proposed origins of this enrichment include metasomatism derived from melting of Nb-rich slab (Sajona et al., 1996) and, in contrast, melting of a geochemically enriched mantle wedge (Castillo et al., 2002). The w...

The petrogenesis of silicic magmas in areas that do not contain continental crust is often unclear. This study examines the composition of domes associated with Mount Makiling stratovolcano, Philippines, to understand the generation of silicic magmas, in an island arc setting. Makiling volcano and associated domes are located in the Macolod Corrido...

Volcanoes were grouped into a scheme according to whether they were associated with 1) micro-continent collisions (Luzon-Taiwan; Palawan-Mindoro), 2) subducting oceanic lithosphere with pelagic sediment cover (Philippine Sea Plate), 3) subducting `transitional' marginal basin with continent-derived sediment cover (South China Sea basin), and 4) inc...

Thesis (Ph. D. in geotechnical engineering and geological sciences)--University of Illinois at Chicago, 1998. Vita. Includes bibliographical references (leaves 171-192). Typescript (photocopy).

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The Angat ophiolite is an incompletely unroofed and structurally dissected ophiolitic mass consisting of layered and massive gabbros, diabase sheeted dikes, tonalites, and pillow basalts. Mapping in the Montalban quadrangle has revealed complex structural relationships between pillow basalts and overlying sediments which hinder an accurate determin...

A concept is currently being developed for an International Philippines Hyperalkaline Analogue Project (IPHAP), which will examine the processes associated with the alteration of bentonite by hyperalkaline fluids of the type that may leach from cement or concrete included in a repository. This paper provides an outline of the requirements and goals...

With a minimum of 6000 tonnes/day municipal waste output, and with NO existing operational sanitary landfill and with incineration illegal, Metro Manila has a very serious solid waste disposal problem. Unsorted municipal waste are being piled in open dumps, the most notorious of which is the Payatas open dump. A recent, tragic garbage-slide in this...

Thesis (M.S. in geological sciences)--University of Illinois at Chicago, 1991. Vita. Includes bibliographical references (leaves 91-97). Typescript (photocopy).

Promoting Environmental Pesearch in Pan-Japan Sea Area : Young Researchers' Network, Schedule: March 8-10,2006,Kanazawa Excel Hotel Tokyu, Japan, Organized by: Kanazawa University 21st-Century COE Program, Environmental Monitoring and Prediction of Long- & Short- Term Dynamics of Pan-Japan Sea Area ; IICRC(Ishikawa International Cooperation Researc...