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JOURNAL OF THE
GEOLOGICAL SOCIETY
OF THE PHILIPPINES
VOL. 73 OCTOBER 2019 NO. 1
ISSN 0368-2331
1
15
33
Mineralogical Zonation of the Sta.
Cruz Nickel Laterite Deposit,
Zambales, Philippines Obtained
from Detailed X-Ray Diffraction
Coupled with Rietveld Refinement
Integrated Remote Sensing in the
Exploration of the Amacan
Geothermal PGeothermal Prospect, Philippines
Petrographic and Paleontological
Characterization of the Capisaan
Limestone Member of Sta. Fe
Formation, Kasibu, Nueva Vizcaya
(Philippines)
K.A. Aquino, C.A. Arcilla, C.S.
Schardt
J.T. Bermido, K.P.G. Guillermo,
O.A. Briola, L.L. Morales, R.D.
Contemplacion, J.A. Caranto
K.L. Garas, L.D. Milay, K.I.N.
IIrorita, R.J.M. Antonio, C.D.U.
Carranza, K.M.Q. Escober, L.G.
Minimo, N.E.B. Pellejera, R.S.
Rodolfo, K.L.U. Tabayocyoc,
M.I.R.D. Balangue-Tarriela,
A.G.S. Fernando
CONTENTS
JOURNAL OF THE
GEOLOGICAL SOCIETY OF THE PHILIPPINES
National Institute of Geological Sciences, University of the Philippines
Diliman, Quezon City 1101 Philippines
Email Address: jgsp@geolsocphil.org
Editor in Chief
Allan Gil S. Fernando, Ph.D.
Associate Editors
Leo T. Armada, Ph.D.
Jillian Aira S. Gabo-Ratio, D.Eng.
Betchaida D. Payot, Ph.D.
Noelynna T. Ramos, D.Sc.
Layout Editors
Yvonne Ivy L. Doyongan
Jose Dominick S. Guballa
Geleen Rica R. Javellana
Justin Jorge R. Padre
Mirko Alessandro C. Uy
GEOLOGICAL SOCIETY OF THE PHILIPPINES
(GSP)
2019 BOARD OF TRUSTEES AND OFFICERS
Dr. Carla B. Dimalanta
Board Chairperson and President
Dr. Teresito C. Bacolcol
Trustee and Vice President
Dr. Jillian Aira S. Gabo-Ratio
Secretary
Dr. Victor B. Maglambayan
Trustee and Treasurer
Dr. Karlo L. Queaño
Trustee and Assistant Secretary
Mr. Ciceron A. Angeles, Jr.
Atty. Marissa P. Cerezo
Dr. Betchaida D. Payot
Dr. Rene Juna R. Claveria
Trustees
JOURNAL OF THE
GEOLOGICAL SOCIETY
OF THE PHILIPPINES
VOL. 73 OCTOBER 2019 NO. 1
ISSN 0368-2331
Mineralogical Zonation of the Sta.
Cruz Nickel Laterite Deposit,
Zambales, Philippines Obtained
from Detailed X-Ray Diffraction
Coupled with Rietveld Refinement
Integrated Remote Sensing in the
Exploration of the Amacan
Geothermal PGeothermal Prospect, Philippines
Petrographic and Paleontological
Characterization of the Capisaan
Limestone Member of Sta. Fe
Formation, Kasibu, Nueva Vizcaya
(Philippines)
1
15
33
K.A. Aquino, C.A. Arcilla, C.S.
Schardt
J.T. Bermido, K.P.G. Guillermo,
O.A. Briola, L.L. Morales, R.D.
Contemplacion, J.A. Caranto
K.L. Garas, L.D. Milay, K.I.N.
IIrorita, R.J.M. Antonio, C.D.U.
Carranza, K.M.Q. Escober, L.G.
Minimo, N.E.B. Pellejera, R.S.
Rodolfo, K.L.U. Tabayocyoc,
M.I.R.D. Balangue-Tarriela,
A.G.S. Fernando
CONTENTS
Aquino et al., 2019
1
MINERALOGICAL ZONATION OF THE STA. CRUZ NICKEL
LATERITE DEPOSIT, ZAMBALES, PHILIPPINES OBTAINED
FROM DETAILED X-RAY DIFFRACTION COUPLED WITH
RIETVELD REFINEMENT
Karmina A. Aquino1*, Carlo A. Arcilla1, Christian S. Schardt2
1 National Institute of Geological Sciences, University of the Philippines,
Diliman, Quezon City, Philippines; *Present address - Department of Earth Sciences,
ETH Zürich - 8092 Zürich, Switzerland; karmina.aquino@erdw.ethz.ch
2 Department of Geological Sciences, University of Minnesota, Duluth, Minnesota, USA
ABSTRACT
The Philippines is the world’s top producer of nickel (Ni) owing to its abundant nickel
laterite deposits. Despite this, Philippine nickel laterite deposits are poorly characterized. In
this paper, detailed mineralogical characterization of a laterite profile from Sta. Cruz,
Zambales using X-ray diffraction coupled with Rietveld refinement revealed two main
horizons: the limonite and saprolite zones, separated by a thin transitional zone. The main
zones are further subdivided into the six subzones: upper limonite, lower limonite, transitional
zone, upper saprolite, lower saprolite, and garnierite veins, based on distinct mineral
assemblages.
Keywords: nickel laterites, Zambales Ophiolite Complex, chemical weathering
INTRODUCTION
Nickel (Ni) laterites are products of chemical weathering of ultramafic rocks in
tropical to subtropical conditions. During chemical weathering, primary minerals
such as olivine, pyroxene, and serpentine break down, resulting in the release and
downward leaching of mobile elements such as Ni, magnesium (Mg), and silicon (Si).
Immobile elements, on the other hand, are residually concentrated within the upper
horizons (Butt and Cluzel, 2013). The differential mobility of elements results in a
laterite profile with a characteristic mineralogical zonation from top to bottom: an
uppermost oxide zone or limonite zone, composed of iron oxides and oxyhydroxides;
a saprolite zone composed of Mg-bearing silicates; and a partially weathered bedrock
(Golightly, 2010).
Ni laterite is the most important nickel resource comprising 70% of the world’s
identified land-based resources, and 40% of the world’s nickel production (Gleeson
et al., 2003; U.S. Geological Survey, 2015; Table 1). The Philippines, which hosts
several laterite mines, was the leading producer of nickel from 2014 to 2016 (Mines
and Geosciences Bureau, 2004). In 2016 alone, the Philippines produced about
Journal of the Geological Society of the Philippines, October 2019
Vol. 73. No. 1
Aquino et al. (2019)
2
500,000 tons of nickel, or about 22.3% of the world’s total Ni production of 2,250,000
tons (U.S. Geological Survey, 2015, 2016, 2017).
Table 1. World Nickel Production and reserves (U.S. Geological Survey, 2017).
MINE PRODUCTION (TONS)
RESERVES
(TONS)
2015
2016
United States
27,200
25,000
160,000
Australia
222,000
206,000
19,000,000
Brazil
160,000
142,000
10,000,000
Canada
235,000
255,000
2,900,000
China
92,900
90,000
2,500,000
Colombia
40,400
36,800
1,100,000
Cuba
56,400
56,000
5,500,000
Dominican Republic
52,400
58,600
1,800,000
Indonesia
130,000
168,500
4,500,000
Madagascar
45,500
48,000
1,600,000
New Caledonia
186,000
205,000
6,700,000
Philippines
554,000
500,000
4,800,000
Russia
269,000
256,000
7,600,000
South Africa
56,700
50,000
3,700,000
Other countries
157,000
150,000
6,500,000
World Total (rounded)
2,280,000
2,250,000
78,000,000
Despite the central role that the Philippines play in the world Ni production,
Philippine nickel laterite deposits are not as well-studied as their New Caledonian or
Australian counterparts. Extensive studies on detailed mineralogy and geochemistry
(e.g., Trescases, 1972; Yang et al., 2013), tectonics (e.g., Cluzel and Vigier, 2008),
as well as morphogenesis and paleoweathering (e.g., Chevillotte et al., 2006; Sevin
et al., 2012) have been conducted on New Caledonian deposits. Other deposits, such
as the nickel laterite deposits of Australia (Elias et al., 1981; Brand & Butt, 2001),
Oman (Al-Khirbash, 2015), Indonesia (Zhu et al., 2012; Fu et al., 2014), Brazil
(Parisot et al., 1989; Colin et al., 1990), Dominican Republic (Tauler et al., 2009),
Cuba (de Oliveira et al., 2001), have also been investigated. On the other hand, there
are very few publications about Philippine laterites, and most of these studies are
unpublished technical reports of mining companies geared towards the economic
potential of these deposits (Mines and Geosciences Bureau, 2004; Gifford, 2013;
Santiago, 2015). In this paper we provide detailed mineralogical characterization of
a profile from the Sta. Cruz nickel laterite deposit in Zambales using X-ray diffraction
and Rietveld refinement.
Aquino et al. (2019)
3
Figure 1. The Zambales Ophiolite Complex is located in west Central Luzon. It is subdivided into three massifs,
the Masinloc, Cabangan, and San Antonio Massifs, separated by west-northwest fault boundaries. The Masinloc
Massif is subdivided into the Acoje and Coto Blocks. Also shown is the location of the Sta. Cruz nickel laterite
deposit. (Modified from Dimalanta et al., 2015
Aquino et al., 2019
4
GEOLOGIC SETTING
Zambales Ophiolite Complex
The Zambales Ophiolite Complex (ZOC), located in west Central Luzon (Figure
1), is a complete ophiolite suite exposing a typical succession of volcanic rocks, dike-
sill complexes, ultramafic and mafic cumulates, residual harzburgite and lherzolites
(Hawkins & Evans, 1983; Abrajano et al., 1989; Rossman et al., 1989; Yumul &
Dimalanta, 1997). The generally N-S trending, east dipping ophiolite complex is
subdivided into three massifs, the Masinloc, Cabangan, and San Antonio Massifs
from north to south, each separated by west-northwest fault boundaries. The Masinloc
Massif is separated from Cabangan Massif by the Iba Fault, while the Cabangan
Massif is separated from the San Antonio Massif by the Subic Bay Fault Zone (Yumul
et al., 1998). The Lawis Fault further subdivides the Masinloc Massif into the Acoje
Block in the north and the Coto Block in the south (Bacuta, 1979; Yumul et al.,
1998).
Sta. Cruz Nickel Laterite Deposit
The Sta. Cruz nickel laterite deposit represents the weathering mantle that
directly overlies the ultramafic massif of the ZOC Acoje Block. The deposit is
characterized by a typical laterite zonation consisting from top to bottom of an upper
limonite layer, saprolite layer, and bedrock (Figure 2). The limonite has
characteristically high Fe and low Ni contents, and occurs in a variety of colors
between red, yellow, and red-yellow hues. The saprolite, on the other hand, has low
Fe and high Ni contents, and occurs as garnierite stringers and coatings in partially
serpentinized peridotites. The bedrock in the study area is composed mostly of
harzburgite with sporadic dunite lenses. Occurrence of chromites has also been
observed within the decomposed serpentinites (Santiago, 2015).
MATERIALS AND METHODS
A total of forty-six (46) samples were systematically collected from the selected
nickel laterite profile in Sta. Cruz, Zambales. Thirty-three (33) soil samples (~500 g
each) were collected at 20 cm interval in the limonite layer, while in the saprolite
layer, thirteen (13) rock samples were collected at 50 cm interval. The samples were
analyzed using a Shimadzu XRD-7000 X-Ray Diffractometer hosted at the National
Institute of Geological Sciences, University of the Philippines (UP NIGS). The
mineral phases from the resulting diffractogram were identified using the PDF4+
Minerals Database by the International Center for Diffraction Data (ICDD), as well
as the Materials Data, Inc. MINERAL database by Nickel and Nichols (2003).
Aquino et al. (2019)
5
Figure 2. The nickel laterite profile investigated in this study showing the limonite and
saprolite zones. The topmost unit is a mechanically transported layer and is therefore not
sampled for this study.
Mineralogical quantification was performed via Rietveld refinement of the
diffractograms using the program Siroquant version 3.0. Siroquant allows
standardless, quantitative analysis of any mineral by using a full-profile Rietveld
method of refining the shape of a theoretical calculated XRD pattern against a
measured experimental pattern (Rietveld, 1969). The calculated theoretical pattern
was the summation of individual calculated standard phase profiles obtained from the
crystallographic data stored in a built-in standard database. Unit cell, linewidths (U,
V, W) and preferred orientation phase parameters of the theoretical phase profiles
were refined against the experimental pattern.
RESULTS AND DISCUSSION
The results of Rietveld analysis conducted on the Sta. Cruz nickel laterite
samples are shown in Figure 3. The crystal structure of the Mn-bearing phases such
as asbolane [(Ni,Co)2-xMn4+(O,OH)4·nH2O] and lithiophorite [(Al,Li)MnO2(OH)2] is
still poorly known and there are currently no available data in the Siroquant databank
for these phases (Siroquant Version 3 User Manual, 2006). Thus, these phases were
not included in the refinement conducted. Nevertheless, investigation of the
diffractograms bearing these phases indicate that they are a minor component in these
Aquino et al. (2019)
6
samples (Figures 4-6). Samples of Rietveld refinement profiles for the different
laterite zones are available upon reasonable request from the authors.
Limonite Zone
The limonite zone is composed predominantly of goethite (79.9 to 96.3 wt%),
and minor hematite (2.9 to 20.2 wt%), and chromite (2.7 to 7.9 wt%) as revealed by
the Rietveld refinement (Figure 3). Two subzones were identified based on mineral
assemblage: [1] the upper limonite, from 0 to 2.4 m, contains goethite+hematite
(Figure 4), while the [2] lower limonite, from 2.6 to 6.2 m, is characterized by the
occurrence of goethite+spinel (Figure 5), The spinel group minerals are most
probably chromite and/or magnetite.
Transition Zone
The transition between the limonite and saprolite occurs at a depth of about 6.4
m and is characterized by mineralogical properties associated with both the limonite
and saprolite zones (Figure 6). In particular, this zone is dominated by goethite (80.5
wt%), a property inherited from the limonite. At the same time, it is characterized by
the occurrence of Mg-bearing silicates such as lizardite (3.1 wt%), chlorite (8.2 wt%),
and actinolite/tremolite (3.8 wt%), which are minerals associated with the saprolite
zone.
Saprolite Zone
The saprolite zone, occurring from 6.5 to 11.0 m, is marked by the dominance
of Mg silicates, mostly lizardite (59.2 to 91.2 wt%), with minor chlorite (9.70 to 17.4
wt%), and tremolite (3.8 to 8.1 wt%). This zone is also characterized by a significant
decrease in the abundance of goethite (5.1 to 12.3 wt%), as well as the appearance of
primary minerals such as forsterite and enstatite (Figure 3). The saprolite is
subdivided into three subzones based on mineral assemblage: [1] upper saprolite, [2]
lower saprolite, and [3] garnierite veins. The upper saprolite (6.5 to 7.0 m) is
composed mostly of the lizardite+chlorite±tremolite±spinel mineral assemblage,
whereas the lower saprolite (7.5 to 10 m) is defined by the lizardite + forsterite +
goethite ± spinel mineral assemblage. The Mg-bearing silicates that occur as
garnierite veins (e.g., LNL650, LNL1100) are composed almost exclusively of
lizardite (up to 91.2 wt%) with minor goethite. The least altered saprolite sample
(LNL1050) is composed mostly of forsterite (51.2 wt%), with lizardite (23.5 wt%),
chlorite (9.7 wt%), actinolite-tremolite (8.5 wt%), and enstatite (7.3 wt%) (Figure 6).
Aquino et al. (2019)
7
Figure 3. Mineral abundances obtained from Rietveld refinement via Siroquant. Also
shown is a schematic diagram showing the corresponding laterite zones base on the
mineralogy of the samples.
Aquino et al. (2019)
8
Figure 4. X-ray diffractograms of the samples taken from the upper limonite zone. Legend: asb – asbolane, chl – chlorite, chr – chromite,
en – enstatite, fo– forsterite, gt – goethite, hem – hematite, lit – lithiphorite, srp – serpentine, trem - tremolite.
Aquino et al. (2019)
9
Figure 5. X-ray diffractograms of the samples taken from the lower limonite zone. Legend: asb – asbolane, chl – chlorite, chr – chromite,
en – enstatite, fo – forsterite, gt – goethite, hem – hematite, lit – lithiphorite, srp – serpentine, trem - tremolite.
Aquino et al. (2019)
10
Figure 6. X-ray diffractograms of the samples taken from the transition - saprolite zone. Legend: asb – asbolane, chl – chlorite, chr –
chromite, en – enstatite, fo – forsterite, gt – goethite, hem – hematite, lit – lithiphorite, srp – serpentine, trem - tremolite.
Aquino et al. (2019)
11
CONCLUSIONS
The nickel laterite profile investigated is composed of two main horizons: the
limonite and saprolite zones, separated by a thin transitional zone. The main zones
are further subdivided into six subzones: upper limonite, lower limonite, transitional
zone, upper saprolite, lower saprolite, and garnierite veins. The upper limonite zone
dominated by goethite is composed of the mineral assemblage goethite+hematite. The
lower limonite zone on the other hand is characterized by the absence of hematite and
the presence of relict chromite. The transitional zone, which marks the first
appearance of Mg silicates, is characterized by a mineral assemblage dominated by
goethite and serpentine and represents the zone of abrupt mineralogical
transformation of the saprolite to limonite zone. The saprolite zone is dominated by
Mg-silicates, mostly serpentine, with the lower saprolite zone marked by the first
appearance of olivine, and the garnierite veins occurring as late stage serpentine veins
that precipitated along fractures.
ACKNOWLEDGEMENTS
The authors acknowledge the Office of the Chancellor of the University of the
Philippines Diliman, through the Office of the Vice Chancellor for Research and
Development, for funding support through the Thesis and Dissertation Grant. Dr.
Rene Juna Claveria is also acknowledged for comments and revisions that helped
improve this manuscript.
REFERENCES
Abrajano, T.A., Pasteris, J.D. and Bacuta, G.C., 1989. Zambales Ophiolite,
Philippines I. Geology and petrology of the critical zone of the Acoje Massif.
Tectonophysics 168 (1-3), 65–100.
Al-Khirbash, S., 2015. Genesis and mineralogical classification of Ni-laterites, Oman
Mountains. Ore Geology Reviews 65 (P1), 199–212.
Bacuta, G.C., 1979. Geology of some Alpine-type chromite deposits in the
Philippines. Journal of the Geological Society of the Philippines 33 (2), 44–80.
Brand, N.W. and Butt, C.R.M., 2001. Weathering, element distribution and
geochemical dispersion at Mt Keith, Western Australia: implication for nickel
sulphide exploration. Geochemistry: Exploration, Environment, Analysis 1 (4),
391–407.
Butt, C.R.M. and Cluzel, D., 2013. Nickel laterite ore deposits: Weathered
serpentinites. Elements 9 (2), 123–128.
Aquino et al. (2019)
12
Chevillotte, V., Chardon, D., Beauvais, A., Maurizot, P. and Colin, F., 2006. Long-
term tropical morphogenesis of New Caledonia (Southwest Pacific):
Importance of positive epeirogeny and climate change. Geomorphology 81 (3–
4), 361–375.
Cluzel, D. and Vigier, B., 2008. Syntectonic mobility of supergene nickel ores of new
caledonia (Southwest Pacific). Evidence from garnierite veins and faulted
regolith. Resource Geology 58 (2), 161–170.
Colin, F., Nahon, D., Trescases, J.J., Melfi, A.J., 1990. Lateritic Weathering of
Pyroxenites at Niquelandia, Goias, Brazil: The Supergene Behavior of Nickel.
Economic Geology 85 (5), 1010-1023.
De Oliveira, S.M.B., Partiti, C.S.deM. and Enzweiler, J., 2001. Ochreous laterite: A
nickel ore from Punta Gorda, Cuba. Journal of South American Earth Sciences
14 (3), 307–317.
Dimalanta, C.B., Salapare, R.C., Faustino-Eslava, D.V., Ramos, N.T., Queaño, K.L.,
Yumul, G.P., Jr. and Yang, T.F., 2015. Post-emplacement history of the
Zambales Ophiolite Complex: Insights from petrography, geochronology and
geochemistry of Neogene clastic rocks. Journal of Asian Earth Sciences 104,
215–227.
Elias, M. and Donaldson, M.J., 1981. Geology , Mineralogy , and Chemistry of
Lateritie Nickel-Cobalt Deposits near Kalgoorlie , Western Australia. Economic
Geology 76, 1775–1783.
Fu, W., Yang, J., Yang, M., Pang, B., Liu, X., Niu, H. and Huang, X., 2014.
Mineralogical and geochemical characteristics of a serpentinite-derived laterite
profile from East Sulawesi, Indonesia: Implications for the lateritization process
and Ni supergene enrichment in the tropical rainforest. Journal of Asian Earth
Sciences 93, 74–88.
Gifford, M.G., 2013. Independent Report on the Nickel Laterite Resource - Agata
North, Philippines, 73 p.
https://s1.q4cdn.com/531881216/files/doc_downloads/Agata-Nickle-Laterite-
NI43-101-April-10-2013.pdf
Gleeson, S.A., Butt, C.R.M. and Elias, M., 2003. Nickel Laterites: A Review. SEG
Newsletter 54, 12–18.
Golightly, J.P., 2010. Progress in understanding the evolution of nickel laterites. In
Goldfarb, R.J., Marsh, E.E. and Monecke, T. (eds.), The Challenge of Finding
New Mineral Resources—Global Metallogeny, Innovative Exploration, and
Aquino et al. (2019)
13
New Discoveries, Society of Economic Geologists Special Publication 15, 451–
485.
Hawkins, J.W. and Evans, C.A., 1983. Geology of the Zambales Range, Luzon,
Philippine Islands - ophiolite derived from an island arc-backarc basin pair. In
Hayes, D.E. (ed.), The Tectonic and Geologic Evolution of Southeast Asian
Seas and Islands, Part 2, American Geophysical Union, Geophysical
Monographs Series 27, 95–123.
Mines and Geosciences Bureau (MGB), 2004. Mineral Resource Information Series
No. 5, 1–14.
Nickel, E.H. and Nicols, M.C., 2003. Mineral database. Materials Data, Inc.
1224 Concannon Blvd. Livermore, CA, USA.
Parisot, J.C., Soubies, F., Audry, P. and Espourteill, F.E., 1989. Some implications
of lateritic weathering on geochemical prospecting - two Brazilian examples.
Journal of Geochemical Exploration 32, 133–147.
Rietveld, H.M., 1969. A profile refinement method for nuclear and magnetic
structures. Journal of Applied Crystallography 2 (2), 65–71.
Rossman, D.L., Castañada, G.C. and Bacuta, G.C., 1989. Geology of the Zambales
ophiolite, Luzon, Philippines. Tectonophysics 168, 1-23.
Santiago, A.P.B., 2015. Evaluation of Ni-bearing saprolite resources contained in
Filipinas Mining Corporation MPSA No. 268-2008-III located Barangay
Guinabon, Sta. Cruz, Zambales, Philippines.
Sevin, B., Ricordel-Prognon, C., Quesnel, F., Cluzel, D., Lesimple, S. and Maurizot,
P., 2012. First palaeomagnetic dating of ferricrete in New Caledonia: New
insight on the morphogenesis and palaeoweathering of “Grande Terre.” Terra
Nova 24 (1), 77–85.
Siroquant Version 3 User Manual (First Edition), 2006. Belconnen, Australia:
Sietronics Pty Limited.
Tauler, E., Proenza, J.A., Galí, S., Lewis, J.F., Labrador, M., García-Romero, E.,
Suarez, M., Longo, F. and Bloise, G., 2009. Ni-sepiolite-falcondoite in
garnierite mineralization from the Falcondo Ni-laterite deposit, Dominican
Republic. Clay Minerals 44 (4), 435–454.
Trescases, J.-J., 1973. Weathering and geochemical behaviour of the elements of
ultramafic rocks in New Caledonia. Bureau of Mineral Resources, Geology and
Geophysics, Canberra 141, 149–161. Retrieved from
Aquino et al. (2019)
14
http://horizon.documentation.ird.fr/exl-
doc/pleins_textes/pleins_textes_5/b_fdi_04-05/06097.pdf
U.S. Geological Survey, 2015. Mineral Commodity Summaries 2015. US Geological
Survey, 196. https://doi.org/10.3133/70140094
U.S. Geological Survey, 2016. Mineral Commodities Summaries 2016. US
Geological Survey. https://doi.org/10.3133/70140094.
U.S. Geological Survey, 2017. Mineral Commodity Summaries 2017. Government
Printing Office. https://doi.org/http://dx.doi.org/10.3133/70140094.
Yang, K., Whitbourn, L., Mason, P. and Huntington, J., 2013. Mapping the chemical
composition of nickel laterites with reflectance spectroscopy at Koniambo, New
Caledonia. Economic Geology 108 (6), 1285–1299.
Yumul, G.P., Jr. and Dimalanta, C.B., 1997. Geology of the Southern Zambales
Ophiolite Complex, (Philippines): Juxtaposed terranes of diverse origin. Journal
of Asian Earth Sciences 15 (4-5), 413–421.
Yumul, G.P., Jr., Dimalanta, C.B., Faustino, D.V. and De Jesus, J.V., 1998.
Translation and docking of an arc terrane: geological and geochemical evidence
from the southern Zambales ophiolite complex, Philippines. Tectonophysics
293 (3–4), 255–272.
Zhu, D.Q., Cui, Y., Hapugoda, S., Vining, K. and Pan, J., 2012. Mineralogy and
crystal chemistry of a low grade nickel laterite ore. Transactions of Nonferrous
Metals Society of China (English Edition) 22 (4), 907–916.
Bermido et al. (2019)
15
INTEGRATED REMOTE SENSING IN THE EXPLORATION OF
THE AMACAN GEOTHERMAL PROSPECT, PHILIPPINES
Jeffrey T. Bermido*, Kevin G. Guillermo, Oliver A. Briola, Leonardo L. Morales,
Releo D. Contemplacion, and Joeffrey A. Caranto
Energy Development Corporation, Pasig City, Philippines;
*bermido.jt@energy.com.ph
ABSTRACT
Remote sensing was applied in this study to obtain preliminary geological understanding
of the Amacan Geothermal Prospect in eastern Mindanao, Philippines. Leonard Kniassef, one
of the active volcanoes in the Philippines, is interpreted to host a high temperature geothermal
system, given its Quaternary volcanism set on a favorable structural environment. In order to
identify priority areas for detailed exploration, this study integrated three remote sensing
techniques namely: geomorphological and lineament analysis, hydrothermal alteration, and
thermal anomaly mapping. Geomorphological and lineament analysis were performed using
freely acquired digital elevation models from Earth Explorer. Major segments of the
Philippine Fault and secondary structures were delineated, as well as arcuate features
representing possible volcanic centers. The Thermal Infrared Sensor (TIRS) Band 10 of
Landsat 8 was also processed to highlight areas with high surface temperatures using a series
of raster calculations. The Operational Land Imager (OLI) bands of Landsat 8 were also
processed using composite and band ratio operations to highlight alteration zones and identify
the alteration type present. Combining the three remote sensing results, five priority areas are
identified to have high geothermal potential and activity. Future ground geoscientific
assessments are recommended to be focused on these areas.
Keywords: remote sensing, geothermal exploration, lineament analysis, hydrothermal
alteration, thermal mapping
INTRODUCTION
Remote sensing has been applied widely in various endeavors, including
geothermal exploration, where it is usually one of the first steps in an overall work
program. As a time- and cost-efficient technology, remote sensing has high impact
on how geologic surveys are planned, especially on identifying priority areas for
detailed assessment. It would also help address the data gap in areas that are difficult
to reach due to challenging terrains and lack of access paths.
Journal of the Geological Society of the Philippines, October 2019
Vol. 73. No. 1
Bermido et al. (2019)
16
Figure 1. (Left) Regional geologic setting of the Amacan Geothermal Prospect (in blue box). Figure modified from
PHIVOLCS (2015). (Right) The geothermal prospect is hosted by the active Leonard Kniassef Volcano and bounded by
two segments of the NW-SE trending Philippine Fault.
Bermido et al. (2019)
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The study is focused on the Amacan Geothermal Prospect, centered on the
Leonard Kniassef Volcano (Figure 1). Carbon dating of the youngest tephra deposits
yielded an age of 1800 ka (Wood, 1980), which makes it one of the active volcanoes
in the Philippines. The area is also generally active with the presence of the Philippine
Trench offshore and the Philippine Fault inland. The sinistral Philippine Fault in
eastern Mindanao cuts through the Holocene sandstones exposed in Mati, Davao
Oriental signifying its active status (Yumul et al., 2008). The Philippine Fault
bifurcates into the Eastern Mindanao Fault in the west and the Mati Fault in the east,
forming a spindle-shaped structure (PHIVOLCS, 2015). This mirrors the fault
architecture of the Philippine Fault in Leyte Island (e.g., West Fault Line and Central
Fault Line) where the Tongonan Geothermal Project and other geothermal prospects
are all straddled. The Philippine Fault in eastern Mindanao also forms a couple with
the younging southward Philippine Trench (Quebral et al., 1996; Lallemand et al.,
1998). The active status of this tectonic couple makes the area seismically active
relative to the rest of the archipelago. This tectonism, which translates to
permeability, is thereby favorable for mineralization and development of geothermal
systems.
Given this impressive regional volcano-tectonic setting, the study aims to refine
and further add to this existing information on the local scale through the application
of remote sensing. This will be used as a reference during the conduct of the
geothermal exploration survey in the area.
MATERIALS AND METHODS
There are two materials used in this remote sensing study. The first dataset is the
Shuttle Radar Topography Mission (STRM) which was used in the geomorphological
and lineament analyses. The digital elevation models (DEMs) were processed to
produce hillshade, slope aspect, and slope gradient maps. Hillshade processing
calculates the illumination value of a cell given a particular azimuth and altitude of a
hypothetical light source. Slopes facing the illumination were highlighted, while
shadows were casted on other slopes. For this study, illumination angle azimuths used
are 045°, 135°, 225°, and 315°. The Z factor of 0.00000912 for the 0-10° latitude of
eastern Mindanao was also used in the analysis. The elevation angle of the
illumination source is set at 20°.
Slope aspect reflects the direction into where the slopes are facing according to
a color scheme displaying the 0-360° azimuth. Aspect maps are found to be suitable
in defining abrupt changes in slope directions that may represent the presence of
geologic structures. This may be indicated by the presence of valleys, ridges, and
Bermido et al. (2019)
18
lineaments. Volcanic deposits can also be differentiated based on the variations in
slope aspect.
Slope gradient processing, usually generated for geohazard analysis, calculates
the slope inclination or steepness of a surface in either degree or percentage values.
According to Braganza (2014), while steep-sided slopes and flat terrains can be
deduced from hillshade maps, the values and degree of flatness or steepness of the
topography is more properly illustrated in the slope gradient map. Broad flat areas are
typically represented by white to green shaded regions, while steep sided slopes are
shaded orange to red.
The second dataset is the Landsat 8 package of eastern Mindanao with
acquisition dated August 2015. This is comprised of Operational Land Imager (OLI)
bands covering Bands 1-7, and Thermal Infrared Sensor (TIRS) bands covering
Bands 10-11. As recommended by the US Geological Survey (2016), Band 11 was
not used due to its large uncertainty factor. A series of steps based on Avdan and
Javanovksa (2016) were applied to convert the OLI Band 10 using raster calculations
in ArcGIS. This includes calculating the Top of Atmosphere Radiance, Brightness
Temperature, Proportion of Vegetation, and the Normalized Difference Vegetation
Index. The final Land Surface Temperature (LST) raster displayed areas with
relatively higher temperatures relative to the background. The raster equation for the
LST is:
where [LST] is the Land Surface Temperature, [BT] is the brightness temperature,
[LSE] is the land surface emissivity, and [w] is the wavelength of emitted radiance at
11.5µm in the TIRS bands. The value of p is equal to 1.438 x 10-2 mK which was
calculated using Planck’s constant, Boltzmann constant, and the speed of light in
vacuum. The process of generating LST maps was simplified by Buhari (2015).
The OLI bands were processed using ArcGIS Model Builder for the
hydrothermal alteration mapping. Color composite processing was performed to
show the spatial distribution of hydrothermal alteration. Three additive colors were
used to display multispectral bands (Mia and Fujimitsu, 2012) corresponding to the
RGB values of a false composite image. The ratio applied in this study was 5:7:6.
Band ratio operation, on the other hand, was employed to identify the type of
alteration present. Abrams ratio (6/7:4/3:5.6) was applied in this study to distinguish
areas with iron oxide and clay alteration.
Bermido et al. (2019)
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The results from the three main techniques were integrated to show priority areas
with geothermal activity and potential, in terms of the presence of structures and
overlaps of hydrothermal alteration with high surface temperatures.
RESULTS AND DISCUSSIONS
Geomorphology
The digital elevation model in Figure 2A was analyzed using several raster
conversions in ArcGIS. Hillshade processing (Figure 2B) was able to display the
terrain variations in the area. The slope gradient map (Figure 2C) showed the
gradation of surface inclinations, while slope aspect (Figure 2D) showed the
directions where the slopes are facing. Figure 3 combines the hillshade and slope
gradient maps to better reflect the terrain variations in the area.
The prospect encapsulates an oblong-shaped terrane centered on Leonard
Kniassef (Figures 2 and 3). Previous geomorphologic interpretations by Paguican
(2012) classified the terrane as a volcanic massif given its low height/basal width
ratio of 0.05, irregular plan shape, and intermediate to high ellipticity. In terms of
dimensions, the massif has a basal area of 366.4 km2. The highest peak in Amacan is
Mt. Dasuran at the south which rises to about 1889 m. The lowest elevations (~100
m) are in the sediment laden plains at the southeast, in the town of Maragusan, and at
the north in Mawab and Nabunturan (Figure 3).
In general, the volcanic massif is characterized by moderately steep slopes with
around 60% in the 18° - 35° interval. An exception is the wide area east of Leonard
Kniassef which is differentiated by a smoother surface of slopes at 11° - 18°. The
more rugged terrain possibly reflects the extent of older volcanic deposits or the flank
of older edifices. This is also supported by the radial drainage pattern surrounding the
center, which is typical in volcanic systems. Contrarily, the smoother terrain east of
Leonard Kniassef represents the possibly younger volcanic deposits. These have
relatively less fault incisions and not as deep as the older deposits.
The slope aspect map also shows the differences between the old and young
deposits within the massif. The older deposits are characterized by slopes facing the
northeast. The younger deposits, on the other hand, have no dominant slope direction.
Paguican and Bursik (2016) explained that areas having slopes facing many
directions may indicate rough material deposits, such as emplaced lava flows or
avalanche and slide toes.
Bermido et al. (2019)
20
Figure 2. DEM processing for geomorphology and structural analyses. (A) Unprocessed,
(B) Hillshade Processing, (C) Slope Gradient Map, and (D) Slope Aspect Map.
Bermido et al. (2019)
21
Figure 3. Superimposition of slope gradient and hillshade maps. Broken lines refer to the
trace of the massif (Paguican, 2012).
Outside the Leonard Kniassef massif, the eastern terrane is characterized by a
N-S trending morphologically homogenous body with almost 80% of the slopes
falling under the 34 - 72° interval. The slopes on its eastern side face the north to the
east, while slopes on its western side face the south to the west. Correlation with
existing maps indicated that this is part of the intrusive complex in the area, identified
as diorite (Quebral et al., 1996).
The western block shares almost similar characteristics with the eastern terrane.
This is characterized by steep slopes with more than 50% within the 34 - 72° slope
interval. It presents an irregular topography with alternating valleys and ridges. Slope
aspect maps shows that it is dominated by slopes facing the NNW-SSE and E-W
directions. Correlation with existing regional maps revealed that the area is underlain
by Late Oligocene to Middle Miocene sediments and limestones (Quebral et al.,
1996).
Bermido et al. (2019)
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Lineament Analysis
The major structures in the Amacan Geothermal Prospect usually form
kilometers of valleys and topographic breaks. These geomorphologic expressions of
structures also influence the drainage pattern in the area. The largest structures are
the segments of the Philippine Fault, represented by the Eastern Mindanao Fault at
the west, and the Mati Fault at the east (PHIVOLCS, 2015; Figure 4). These two
structures form an apparent dilational jog in eastern Mindanao striking at about 340°
azimuth. A sinistral sense is applied for these structures being consistent with the
sinistral kinematics of the entire Philippine Fault. The next two most prominent
structures are the Manat Fault and Amacan Fault which strike at about 315° azimuth
(Figure 4). Manat Fault mainly controls Manat River, while Amacan Fault has its best
geomorphologic expression along Malumon River. Theoretical predictions from
wrench tectonics of the main splays of the Philippine Fault indicate that these two
major structures would have a similar sinistral sense as synthetic shears.
Figure 4. Remote sensing-based structural map of the Amacan Geothermal Prospect. (PF
for Philippine Fault).
Bermido et al. (2019)
23
Another important structure is the E-W trending Masara Fault which almost
crosses the entire latitude of the prospect (Figure 4). The structure is prominent from
hillshade images and has a strike of 095° azimuth. Theoretical predictions show that
structures of this orientation would have a tensional character being parallel to the
maximum horizontal stress in Mindanao. Two parallel NE-SW trending structures
also cut the prospect, namely the Lumanggang and Maraut Faults (Figure 4).
Lumanggang Fault has its most obvious trace west of Lake Leonard while Maraut
Fault has its main trace along Maraut River. Antithetic sense is predicted for this
structural orientation.
Notable N-S trending structures are delineated near the western and eastern
borders of the prospect, forming the largest river systems in the area: Hijo and Agusan
Rivers (Figure 4). Both Hijo and Agusan River Faults appear as fault contacts which
juxtaposed the terranes at the west and east to the massif hosting the geothermal
prospect. Theoretical prediction of these structures indicates compression being
perpendicular to the maximum horizontal stress.
Aside from linear structures, there are also three arcuate features which may
represent the distribution of volcanic centers in the area (Figure 4). The largest is
Masara Caldera, which is~9 km in diameter and has a N-S elongation. Within the
Masara Caldera is Leonard Caldera with its circular plan shape measuring ~2 km. A
collapse feature named as the Maraut Collapse is also observed on the southern rim
of the Masara Caldera. The collapse feature has a NE-SW elongation following the
configuration of the Maraut Fault.
Thermal Mapping
Land surface temperature (LST) is defined as the skin temperature of the land
surface or the temperature felt when the ground is touched (Avdan and Jovanovska,
2016). The LST map (Figure 5E) was generated using a series of raster calculations
presented in Figures 5A - 5D. As shown in the final map, thermal highs are displayed
in warmer reddish coloration, while relatively colder areas are in blue. The maximum
temperature calculated is about 31°C, which is similar with other land surface
temperature maps in other geothermal areas (Meneses, 2015).
Figure 5E also shows the documented locations of thermal manifestations in the
area such as hot and warm springs according to the Department of Energy (DOE,
2019). A linear high temperature anomaly is observed near the Manat thermal springs.
Similarly, the locations of the Leonard-Mainit-APEX, Manat-Bucal, and Amacan
thermal areas also correlate well with the thermal anomalies. Other thermal areas with
nearby high temperature anomalies are in Maragusan and Maraut. Contrarily,
relatively colder areas are observed in the northwest, northeast, and central-south
Bermido et al. (2019)
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Figure 5. Raster calculations converting Band 10 to Land Surface Temperature. The prospect is highlighted by the
blue boxes. (A) Top of Atmosphere Radiance, (B) Brightness Temperature, (C) Normalized Difference Vegetative
Index (NDVI), (D) Land Surface Emissivity, and (E) Land Surface Temperature Map with documented thermal
areas in red circles (DOE, 2019). Legend shows temperature in degrees Celsius.
Bermido et al. (2019)
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portion of the prospect. This may be due to thick vegetation or the lack of geothermal
activity at the surface. The TIRS image was also captured in the morning given the
sun elevation of 67°.
Hydrothermal Alteration Mapping
Previous studies explained the fact that certain minerals associated with
hydrothermal processes, such as iron-bearing minerals (e.g., goethite, hematite,
jarosite, and limonite), and hydroxyl bearing minerals (e.g., kaolinite and K-micas)
show diagnostic spectral features that allow their remote identification (Hunt, 1980;
Mia and Fujimitsu, 2012). Iron oxide is said to be a common constituent of alteration
zones associated with hydrothermal sulfide deposits (Poormirzaee and Oskouei,
2010). The major iron oxide species, formed from the weathering of sulfides, absorb
energy at different frequencies providing a means of discrimination using
hyperspectal scanners (Taranik et al., 1991). Hydroxyl bearing minerals, on the other
hand, form the most widespread product of alteration.
Using OLI bands of Landsat 8, hydrothermal alteration maps were prepared as
shown in Figure 6. Composite ratio operation 5:7:6 remotely identified areas with
hydrothermal alteration in the study area. The spatial distribution of altered grounds
is observed along major drainages where the reflectance is coming from either the
altered exposed bedrock or fluvial deposits with altered material. Hydrothermal
alteration is also evident in mining areas within the Masara Caldera and near thermal
areas. Relatively wider distribution of hydrothermal alteration is observed along
Manat-Bucal, Maraut, Mainit-Apex, Maragusan, Amacan, and around Lake Leonard.
The Abrams ratio (6/7:4/3:5/6) was able to differentiate the type of alteration
minerals present (Figure 6). Iron-oxide minerals such as limonite, hematite, and
jarosite were discriminated as yellow to yellow-green, while hydroxyl bearing
minerals such as clays appeared as red. The purple coloration which dominates the
resulting image corresponds to the background that is possibly unaltered or vegetated
(i.e., no exposures). As with band ratio operation, yellow to yellowish green areas are
concentrated along major drainages, known thermal areas, and iron-oxide altered
outcrops. The largest iron oxide altered area is in Mainit-APEX. Increasing the
contrast of the image also enabled better accentuation of the clay altered regions in
red. The largest clay altered area is observed in Amacan. Patches of clay alteration
are also observed in Maraut and Lake Leonard.
Bermido et al. (2019)
26
Figure 6. Left: Composite ratio operation 5:7:6 showing areas that are hydrothermally altered. Right: Abrams
ratio operation (6/7:4/3:5/6) distinguishing iron oxide (FeO) and clay (Cl) minerals.
Bermido et al. (2019)
27
Integrated Remote Sensing and Recommended Priority Areas for Exploration
Figure 7 superimposes the three generated images to present an integrated
remote sensing map. The prospect is narrowed down into five priority areas: Area A
– Lake Leonard-Mainit-APEX, B – Amacan, C – Manat-Bucal, D – Maraut, and E –
Maragusan. These areas appear to indicate geothermal activity given the overlaps of
thermal anomalies and alteration zones, as well as the presence of major structures.
The map is dominantly purple colored due to the Abrams ratio (Figure 6) basemap.
The lighter regions in the map are thermal highs, while the dark regions represent
thermal lows or no anomalies.
Area A as shown in Figure 8A is centered on Leonard Caldera, postulated to be
the youngest volcanic center in the area as it cross cuts the Masara Caldera. The
Leonard Caldera is located in between the NW-SE trending Amacan and Manat
Faults, where majority of the thermal manifestations are all confined. Area A hosts
the NE-SW trending Lumanggang Fault in the west and Maraut Fault in the east. High
thermal anomaly and hydrothermal alteration composed of clay and iron oxides also
coincide around the lake, most notably in its southern portion. West of the lake is a
high iron oxide anomaly which measures about a kilometer in length and follows the
trend of Lumanggang Fault. Minor overlaps between the high thermal and alteration
anomalies are also noted within the southern half of the Masara Caldera which
encloses a gold-copper district. Peculiarly, no distinct anomalies were mapped in the
reported Mainit thermal area.
About three kilometers south of Lake Leonard is Area B (Figure 8B) which
corresponds to the Amacan area. A large thermal anomaly of about two kilometers is
observed which also coincides with dominant clay alteration. This anomaly area is
transected by arcuate features that represent the eastern extent of the Masara Caldera.
Permeability is also facilitated by the major Amacan Fault which cuts through the
western side of the area. Area B is also located on the flanks of Ugos Dome which is
a candidate heat source (DOE, 2019). Area C (Figure 8C) is delineated following the
trace of the major NW-SE trending Manat Fault. High permeability from this
structure is perceived considering the overlaps of the thermal anomalies and alteration
zones along its trace. The remarkably linear thermal anomaly which measures for
about two kilometers also hosts several documented hot springs in Mainit and Bucal
areas. The hot springs and anomalies are also observed to occur at the intersections
of the Manat Fault and the secondary NE-SW trending minor structures.
Area D (Figure 8D) is located in Maraut at the southwestern portion of the
Amacan prospect, where similar high temperature springs are also documented.
Unlike Areas B and C, the anomalies do not follow the trend of the Maraut Fault or
Bermido et al. (2019)
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Figure 7. Five priority areas identified for detailed exploration in yellow circles.
Bermido et al. (2019)
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Figure 8. Close up maps of the five priority areas showing the overlap of thermal
anomalies, hydrothermal alteration using Abrams ratio, and presence of structures. Green
dots are the location of the thermal manifestations. Light purple regions are thermal highs
while dark purple regions are relatively thermal lows. (A) Leonard-Mainit-APEX for
Area A, (B) Amacan for Area B, (C) Manat-Bucal for Area C, (D) Maraut River for Area
D, and (E) Maragusan for Area E. The Mawab area (F) shows no anomaly. FeO indicates
iron oxide anomalies, while Cl indicates clay.
Bermido et al. (2019)
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the Maraut Collapse. Thermal anomalies occur as sporadic bodies around the area
with alteration by clay and iron oxides. Area E (Figure 8E) is also a recommended
area for exploration in Maragusan town. The area hosts two reported warm springs,
with nearby high clustering of iron oxide alteration enclosed in a high thermal
anomaly body. Figure 8F shows an area in Mawab at the northwestern portion of the
prospect showing generally no thermal anomalies, hydrothermal alteration,
documented thermal manifestations, and major structures. This represents the
background in the prospect showing no clear geothermal activity at the surface.
SUMMARY AND CONCLUSIONS
The study integrated known remote sensing techniques to determine priority
areas for geothermal exploration in the Amacan Geothermal Prospect in eastern
Mindanao. Geomorphologic analysis from slope aspect, slope gradient, and hillshade
identified two major deposits within the massif. The western and eastern terranes
bounding the massif also show different geomorphologic signatures relative to the
volcanic complex. Lineament analysis revealed that the major structures are oriented
NW-SE, NE-SW, N-S, and E-W. These structures resulted from the activity of the
Philippine Fault in the area associated with the ongoing subduction along the
Philippine Trench. Three arcuate features are also identified, namely the large Masara
Caldera, young Leonard Caldera, and the elongate Maraut Collapse.
Thermal mapping showed areas of high temperatures relative to the background,
especially near thermal areas and open grounds with mining activity or lacking
vegetation. The highest temperature measured is 31°C, similar with other geothermal
areas in the Philippines. Hydrothermal alteration mapping was also able to
discriminate iron oxide and clay alterations. Based on the integrated remote sensing
results, the large prospect is narrowed down into five priority areas for detailed
geoscientific assessments: Leonard-Mainit-Apex, Amacan, Manat-Bucal, Maraut,
and Maragusan.
Overall, remote sensing proved its efficiency as a tool in determining areas with
high geothermal potential and activity. This study however stresses the importance
of ground validation to continuously improve and calibrate the remote sensing
process. Given that the area also hosts mining districts, the anomalies may not just
reflect the current hydrothermal system but from the fossil systems as well.
Bermido et al. (2019)
31
ACKNOWLEDGEMENTS
The authors acknowledge NASA’s Earth Explorer for the free datasets used in
the processing of data. The study would also like to thank EDC management for the
approval to publish the results of the study. Special thanks as well to Mitch Stark and
Paul Karson Alanis for the constructive review of the paper which led to its
improvement.
REFERENCES
Avdan U. and Jovanovska G., 2016. Algorithm for Automated Mapping of Land
Surface Temperature Using LANDSAT 8 Satellite Data; Journal of Sensors,
Volume 2016.
Braganza, J., 2014. Volcano-tectonic evolution of the Bacon-Manito Geothermal
Project, Sorsogon, Philippines (MSc Thesis). The University of Auckland.
202 p.
Buhari, U., 2015. Landsat 8: Estimating Land Surface Temperature Using ArcGIS.
Retrieved 22 Sept 2017; https://www.youtube.com/watch?v=uDQo2a5e7dM
Department of Energy (DOE), 2019. Amacan Geothermal Prospect. Retrieved 01
July 1, 2019; https://www.doe.gov.ph/amacan-geothermal-prospect.
Hunt G.R., 1990.Near Infrared (1.3–2.4 μm) spectra of alteration minerals – potential
for use in remote sensing. Geophysics 44, 1974–1986.
Lallemand, S., Popoff, M., Cadet, J.-P., Deffontaines, B., Bader, A.G., Pubellier, M.
and Rangin, C., 1998. The junction between the central and southern
Philippine Trench. Journal of Geophysical Research 103, 933−950.
Meneses, S.M., 2015. Thermal Remote Sensing at Leyte Geothermal Production
Field using Mono-window Algoriths. Proceedings World Geothermal
Congress. Melbourne, Australia.
Mia, B., & Fujimitsu, Y., 2012. Mapping hydrothermal altered mineral deposits using
Landsat 7 ETM+ image in and around Kuju volcano, Kyushu, Japan. Journal
Earth System Science 121 (4), 1049-1057.
Paguican E.M.R and Bursik M.I., 2016. Tectonic Geomorphology and Volcano-
Tectonic Interaction in the Eastern Boundary of the Southern Cascades (Hat
Creek Graben Region), California, USA. Frontiers in Earth Science 4, DOI:
10.3389/feart.2016.00076.
Bermido et al. (2019)
32
Paguican E.M.R., 2012. The structure, morphology, and surface texture of debris
avalanche deposits: field and remote sensing mapping and analogue
modelling. Earth Sciences. Université Blaise Pascal - Clermont-Ferrand II.
346 p.
PHIVOLCS, 2015. Distribution of active faults and trenches in the Philippines.
Poormirzaee, R. and Oskouei, M.M., 2009. Use of spectral analysis for detection of
alterations in ETM data, Yazd, Iran. Applied Geomatics 2 (4), 147-154.
Quebral, R., Pubellier, M. and Rangin, C., 1996. The onset of movement on the
Philippine fault in eastern Mindanao: A transition from a collision to strike
slip environment. Tectonics 15, 713−726.
Taranik D.L., Kruse F.A., Goetz A.F.H. and Atkinson W.W., 1991. Remote sensing
of ferric iron minerals as guides for gold exploration; Proceedings of the
Eighth Thematic Conference on Geologic Remote Sensing, Denver,
Colorado, 197–228.
US Geological Survey, 2016. Landsat 8 Data Users Handbook.
Wood, P., 1980. A Report on a visit to the Philippines, February 1980. Unpublished
report. NZ DSIR, 1980.
Yumul G.P., Dimalanta C.B., Maglambayan, V.B., and Marquez, E.J., 2008. Tectonic
setting of a composite terrane: A review of the Philippine arc system.
Geosciences Journal 12 (1), 7-17.
Garas et al. (2019)
33
PETROGRAPHIC AND PALEONTOLOGICAL
CHARACTERIZATION OF THE CAPISAAN
LIMESTONE MEMBER OF STA. FE FORMATION,
KASIBU, NUEVA VIZCAYA (PHILIPPINES)
Kevin L. Garas*, Leo D. Milay, Kryztal Irish N. Irorita, Richard Jason M.
Antonio, Coleen Dorothy U. Carranza, Karla Marlyn Q. Escober, Likha G.
Minimo, Nicole Eloise B. Pellejera, Raymond S. Rodolfo, Kenny Lynne U.
Tabayocyoc, Ma. Ines Rosana D. Balangue-Tarriela, and Allan Gil S. Fernando
National Institute of Geological Sciences, University of the Philippines,
Diliman, Quezon City, Philippines; *Present address - Lands Geological Survey
Division, MGB – Central Office, North Avenue, Diliman, Quezon City 1101;
kgaras91@gmail.com; agsfernando@yahoo.com
ABSTRACT
The Sta. Fe Formation is considered to be the oldest sedimentary sequence covering the
Northern Sierra Madre stratigraphic group. The formation consists of limestone and clastic
members. The limestone member is fossiliferous, predominantly composed of coral
fragments, red algae, pelecypods, gastropods, ostracods, echinoid spines and foraminifera.
Petrographic analysis of the limestones exposed in Kasibu, Nueva Vizcaya revealed the
presence of bioclastic wackestone and foraminiferal grainstone units representing the shelf
lagoon with open marine influence environment, and grainstone-packstone and reef rudstone
units representing the foreslope/reef flank environment. Based on the large benthic
foraminifera assemblage consisting of Lepidocyclina spp. (L. formosa, L. inflata and L.
[Eulepedina] richtofeni), Flosculinella botangensis, Cycloclypeus spp., and Miogypsina spp.,
an Early Miocene age is assigned to the limestone member of Sta. Fe Formation. The result
suggests that the limestone unit is younger than the turbidite/clastic member of Sta Fe.
Formation. It is proposed in the present study that the limestone member of the Sta. Fe
Formation be recognized as a formal lithostratigraphic unit and be named Capisaan Limestone
Member after the exposures in Barangay Capisaan, Kasibu, Nueva Vizcaya.
Keywords: Sta. Fe Formation, Capisaan Limestone Member, Nueva Vizcaya, limestone,
petrography, large benthic foraminifera
INTRODUCTION
The Philippines has a number of sedimentary basins filled with deep to shallow
marine sediments ranging from Oligocene to Recent in age (MGB, 2010). Within
these basins are carbonate rocks intercalated with clastic and volcaniclastic units. The
carbonate rocks are associated with major reef building events during the Middle
Journal of the Geological Society of the Philippines, October 2019
Vol. 73. No. 1
Garas et al. (2019)
34
Cenozoic (Early to Late Miocene) and Pliocene (Carozzi et al., 1976). Despite the
widespread occurrence of limestone bodies in the Philippines, however, very few
petrologic characterization studies are available. These include the pioneering work
of Carozzi et al. (1976) on the Miocene reef systems in the Visayas Region (including
Iloilo Basin, Visayan Sea Basin and part of the Southern Luzon Basin), and the work
of Foronda and Schoell (1987) in the study of the Binangonan Formation in Rizal
Province. Carozzi et al. (1976) studied the Miocene carbonates in the Visayas Region
and came up with the reconstruction of a reef system model as well as a model of
distribution of large benthic foraminifera of Miocene reef systems of the Visayas.
Foronda and Schoell (1987) used the microfacies approach to deduce how the
different carbonate sub-environments of the Binangonan Formation were distributed
with respect to one another through time. A more recent study is that of Fournier et
al. (2004) on the investigation of the paleoenvironment of the Oligocene-Miocene
build-ups of Malampaya (offshore Palawan, Philippines). In the paper, petrographic
analysis of shallow water carbonates and the effects of relative sea level change in
the carbonate build-up during the Early Miocene were investigated.
Similar research to characterize sediment facies, age and depositional
environments was done in Labayug Limestone, a Late Miocene unit exposed in Sison,
Pangasinan. This work utilized petrographic and paleontological approach to reveal
the paleodepositional setting of shallow to deep subtidal marine environments of the
Labayug Formation (Fernandez, 1996). Javelosa (1994) conducted facies
characterization of Quaternary limestones in southwestern Bohol and correlated this
to the retreat of Maribojoc Bay from Pleistocene to Holocene.
In the course of the detailed geologic mapping of northeastern Kasibu, Nueva
Vizcaya in 2011 by the Geology 170 Class (Field Geology) of the National Institute
of Geological Sciences, UP Diliman (UP NIGS), limestone samples were collected
and subjected to paleontological and petrographic analyses. The paper aims to (1)
characterize the limestone units based on their skeletal (i.e., bioclast), non-skeletal,
micrite and cement components, (2) determine the paleodepositional conditions, and
(3) determine the age of limestone units of Sta. Fe Formation using large benthic
foraminifera and compare with previously reported age assignment.
STUDY AREA
The study area is located in the northeastern part of the municipality of Kasibu,
Nueva Vizcaya, bounded by 16o18’37” to 16o24’38” N latitude and by 121o17’44” to
121o25’5” E longitude (Figure 1). The study area is bounded by the Palali Range in
the north and Mamparang Mountains in the south, covering an area of approximately
132 km2.
Garas et al. (2019)
35
Figure 1. Location Map of Kasibu, Nueva Vizcaya.
Garas et al. (2019)
36
Several limestone exposures were observed in Barangays Malabing, Wangal,
Capisaan and Dilaping. These areas are situated within the north-south trending
Malabing Valley, which is characterized by a 2 km-wide valley plain dotted with
karst towers and hills. The karst towers have numerous, steep-sided peaks but are
usually hidden by thick shrubs and small trees. These geomorphological features are
situated at 710 to 826 m above sea level (masl).
The valley is bounded by a N-S trending eastern ridge and a NW-SE trending
western ridge. The eastern ridge has a linear, steep-sided ridge crest with five
prominent peaks >1,000 masl. This is transected by parallel deep ravines along the
ENE-WSW direction forming several saddle or low gaps within the ridge crest. These
ravines correspond to lineations and faults delineated in the area by previous geologic
surveys. Major geologic structures possibly controlled the morphology of the valley.
It is highly evident through the presence of angular stream bents and very steeply-
sloping ridges which terminate abruptly to the flat valley plains. The study area is
known for the Capisaan Cave System which is considered the fifth longest in the
country (https://nuevavizcaya.gov.ph/nueva-vizcaya-tourism/points-of-interest/
capisaan -cave/). The cave system forms part of the karst topography in the area which
is more pronounced in the southern-southeastern part of the study area (Figure 2).
Figure 2. Karst towers in the southeastern portion of Kasibu underlain by the limestone
member of Sta. Fe. Formation (= Capisaan Limestone Member).
Garas et al. (2019)
37
Kasibu is also a known mineral-rich municipality and a site for several mining
operations, both large- and small-scale. OceanaGold Corporation has an operating
gold and copper mine in Didipio, which is located east of the study area. The gold-
copper deposits are hosted within the multiphase Didipio Stock, which is part the
Didipio Intrusive Complex, a large alkalic intrusive body (Griffiths et al., 2014).
Another mining project is located north of the study area, the FCF Minerals
Corporation’s Runruno Project, which is a gold-molybdenum deposit hosted within
a large alkaline volcanic complex called the Runruno Volcanic Complex (Taylor,
2013).
GEOLOGY AND STRATIGRAPHY OF THE AREA
The study area is situated at the southern part of the Cagayan Valley Basin, a
suite of Oligocene to Recent sedimentary formations underlain by Eocene to
Oligocene volcano-sedimentary rocks (MGB, 2010). Peña (2008) included the study
area in the Northern Sierra Madre-Caraballo stratigraphic group consisting of the
following units (from oldest to youngest): Middle to Late Eocene Caraballo
Formation, Late Oligocene Mamparang Formation, Late Oligocene to Early Miocene
Sta. Fe Formation, late Early Miocene Palali Formation, Middle Miocene Aglipay
Formation, late Middle Miocene to early Late Miocene Palanan Formation, and the
Pliocene Pantabangan Formation. Several intrusive rocks are also present in the area,
including the Eocene Coastal Batholith (renamed as the Dinalungan Diorite Complex
by MGB [2005; in Peña, 2008]), late Early Oligocene to early Early Miocene Dupax
Diorite Complex, and the late Late Oligocene to early Early Miocene Cordon Syenite
Complex. Four formational units were recognized in the study area: Mamparang
Formation, Cordon Syenite Complex, Dupax Diorite Complex and the limestones of
the Sta. Fe Formation (Figures 3 and 4).
The focus of this paper is the Sta. Fe Formation, which represents the oldest
sedimentary sequence covering the northern Sierra Madre area (MGB, 2010). Two
members are recognized within the formation: a 100 m thick lower limestone unit and
an upper clastic member (MMAJ-JICA, 1975; MGB, 2010). Both units have yet to
be given formal lithostratigraphic designation (i.e., as named members of the Sta. Fe
Formation). The formation crops out in Dalton Pass, near the provincial boundary of
Nueva Ecija and Nueva Vizcaya (MMAJ-JICA, 1977). Based on large benthic
foraminifera, the limestone was given an age of Late Oligocene to Early Miocene.
The Sta. Fe Formation is synonymous with Disubini Formation, which is exposed in
its type locality in Disubini River in San Ildefonso Peninsula and in Palanan and
Dinapigue, Isabela (Billedo, 1994). The formation unconformably overlies the
Isabela Ophiolite and has a lower limestone member and upper turbidite member
Garas et al. (2019)
38
Figure 3. Distribution Map of the Capisaan Limestone Member of Sta. Fe Formation in Kasibu. Geologic map by the 2011 Geology
170 Class of UP NIGS (La Rosa et al., in preparation).
Garas et al. (2019)
39
Figure 4. Stratigraphic Column of Kasibu (2011 Geology 170 Class of UP NIGS [La
Rosa et al., in preparation]).
consisting of shale-sandstone interbeds with minor limestone layers (Peña, 2008).
Paleontologic dating of limestone beds within the upper turbidite sequence using
large benthic foraminifera suggests a Late Oligocene to Early Miocene age. Shale
samples from the upper turbidite member, on the other hand, yielded a nannofossil
assemblage indicative of the Nannofossil Zone NP25, equivalent to a late Late
Oligocene age (MGB, 2010).
METHODOLOGY
The limestones in northeastern Kasibu were mapped in a 1:50,000 scale.
Geographic location of the limestone outcrops were determined using a hand-held
GPS. The samples were properly packed and labeled for petrographic and
paleontological analyses. The geologic map was generated by the 2011 Geology 170
Class of UP NIGS using MapInfo Professional 10. Thin sections of the samples were
prepared at UP NIGS. A total of 23 samples were subjected to petrographic analysis
using a polarizing microscope to classify the limestones based on depositional texture
using the Dunham (1962) Classification. Large benthic foraminifera were also
Garas et al. (2019)
40
Table 1. Petrographic characterization of limestone samples from northeastern Kasibu, Nueva Vizcaya.
Garas et al. (2019)
41
Plate I: Sample NV-D11-III-28D (Packstone): (1) Echinoid spine and (2) large benthic
foraminifera in micritic matrix; Sample NV-D11-IX-21 (Grainstone): (3) Foraminiferal
bioclasts enclosed by (4) micritic matrix and sparry calcite cement; Sample NV-D11-NA-
1A (Grainstone-packstone): (5) Encrusting red algae, Carpenteria sp. (encrusting algae),
and foraminifera fragments; Sample NV-D11-NA-1B (Grainstone-packstone): (6) Red
algae and (7) benthic foraminifera comprise the bioclastic component of the sample;
Sample NV-D11-VII-10 (Packstone): (8) Bioclasts in micritic matrix, (9) Axial section
of Lepidocyclina sp., (10) Amphistegina sp. and rotaliid (small benthic foraminifera).
Scale bar = 1 mm.
Garas et al. (2019)
42
Plate II: Sample NV-D11-XI-1B (Reef rudstone): (1, 3) Coral fragments, (2) red algae,
(4) transverse section of Flosculinella botangensis; Sample NV-D11-X-25A (Bioclastic
wackestone): (5) mollusk fragment showing nacreous and prismatic layers; Sample NV-
D11-XI-1C (Bioclastic wackestone): (6-7) Axial/subaxial section of Flosculinella
botangensis, (8) foraminifera and red algae bioclasts; Sample NV-D11-XI-2B
(Grainstone-packstone): (9) Small benthic foraminifera and red algae bioclasts (10)
Bioclasts bound by drusy calcite cement and micrite. Scale bar = 1 mm.
Garas et al. (2019)
43
Plate III: Sample NV-D11-XI-2C (Bioclastic wackestone): (1) Lepidocyclina sp.
bioclasts embedded in micrite, (2) Axial section of Sphaerogypsina sp., (3) mollusk
fragment; Sample NV-D11-XI-3A (Bioclastic wackestone): (4) Transverse section of
Lepidocyclina sp.; Sample NV-D11-XI-3B (Bioclastic wackestone): (5) Micritic matrix
and sparry calcite cement; Sample NV-D11-XI-4A (Bioclastic wackestone): (6) Axial
section of Cycloclypeus sp. (center) and equatorial section of Lepidocyclina sp. (upper);
Sample NV-D11-XI-5B (Foraminiferal grainstone): (7) Bioclasts of Lepidocyclina sp.
and Operculina sp., (8) Bioclasts of rotaliid and transverse section of a large benthic
foraminifera, (9) Bioclasts of red algae and Lepidocyclina sp., (10) Axial section of
Lepidocyclina sp. showing a defined protoconch. Scale bar = 1 mm.
Garas et al. (2019)
44
Plate IV: Sample NV-D11-XI-5B (Foraminiferal grainstone): (1) Bioclasts of large
benthic foraminifera, (2) Cycloclypeus sp. fragments, (3) Bioclasts of large benthic and
planktonic foraminifera; Sample NV-D11-XI-5A (Bioclastic wackestone): (4) Bioclasts
of Lepidocyclina sp., (5) Transverse section of Miogypsina sp., (6) Lepidocyclina sp.
showing defined protoconch and deuteroconch; Sample NV-D11-XI-5A-2 (Bioclastic
packstone): (7) Lepidocyclina sp., (8) Transverse section of a rotaliid, (9) Fragments of
Operculina sp. and Cycloclypeus sp., (10) Bioclast of Lepidocyclina sp. Scale bar = 1
mm.
Garas et al. (2019)
45
identified from the thin sections to determine the age of the limestone.
Photomicrographs of representative textural types and bioclasts present in the
samples were also obtained using a Zeiss polarizing microscope at the Nannoworks
Laboratory, UP NIGS. Petrographic slides, archive samples, and original
photomicrographs are stored at UP NIGS. Table 1 shows the results of the
petrographic analysis of the limestones, while Plates I-IV show the different textures
and bioclasts present in the study area.
RESULTS AND DISCUSSION
In northeastern Kasibu, only the limestone member of the Sta. Fe Formation was
observed in the field. Limestone outcrops are mostly distributed along the eastern part
of the study area, within Barangays Cabinuangan, Binogawan, Malabing, Wangal and
Capisaan (Figure 3). Few limestone exposures occur southwest of the study area in
Barangay Dilaping. The presence of caves and other karst features evident in
topographic maps, such as karst towers, was used to delineate the distribution of Sta.
Fe Formation. The limestone units are reported to lie unconformably over the Dupax
Diorite Complex and Caraballo Formation (MGB, 2010). In Brgy. Wangal, a
nonconformity was observed between the foid andesites of the Mamparang
Formation and the limestone (Figure 5).
Figure 5. The non-conformable contact between the foid andesite of Mamparang
Formation and Capisaan Limestone Member in Brgy. Wangal.
Garas et al. (2019)
46
Outcrop Descriptions
The white to gray limestones vary from massive to bedded (Figure 6). The beds
are thinly bedded (20-50 cm thick), striking NE and dipping SE/NW. Based on grain
size (i.e., size of bioclasts), the limestones were classified in the field either as
calcirudites (floatstones) or calcarenites, although the limestones in Brgy. Malabing
are classified as calcilutites, characterized by its chalky texture. The limestones
exposed in Brgy. Dilaping, on the other hand, are more crystalline, although coral
bioclasts are still visible in the outcrops. In Brgy. Capisaan, the bioclast percentages
range from 10-70%, with the bedded limestones containing abundant bioclasts
compared to the massive limestones. Fossils observed in the limestone outcrops
include coral fragments, gastropods, pelecypods, and echinoid spines (Figure 7). The
presence of coral fragments, particularly the finger corals, suggests that limestone
deposition was far from the main reef crest, either within the backreef or foreslope
environment. The limestones from Brgy. Wangal contain lesser (~10%) and smaller
bioclasts than the Capisaan limestones. Some portions of the limestones in Wangal
are gray in color and contain large benthic foraminifera that are aligned in a certain
direction (Figure 7).
Figure 6. Outcrops of the Capisaan Limestone Member of Sta. Fe Formation in Kasibu:
(A) Bedded limestone in Brgy. Capisaan with finger corals, gastropods and pelecypods;
(B) Massive limestone in Brgy. Capisaan with corals, gastropods and pelecypods; (C)
Limestone outcrop in Brgy. Capisaan containing gastropod shells, corals and pelecypods;
(D) Limestone in Brgy. Wangal containing coral rubbles and mollusk.
Garas et al. (2019)
47
Petrographic Characterization
Table 1 shows the results of the petrographic analysis of the limestone samples
indicating the percentage of micrite, sparite and bioclasts. The following textures
were identified in the study area: (a) wackestones (mud-supported with >10%
bioclasts); (b) packstones (grain-supported containing less mud than wackestones);
and (c) grainstones (grain-supported and lacks mud). It should be noted that
floatstones were also observed in Capisaan, although no thin section was prepared
from the samples. Among the bioclasts observed in the samples, large benthic
foraminifera are probably the most important as they are not only useful for
paleoenvironmental reconstruction but also in determining the age of the limestone
member of Sta. Fe Formation (see discussion on paleontological analysis). Other
bioclasts observed in the samples include coral fragments (Plate II-1, 3), echinoid
spines (Plate I-1), red algae (Plate I-5, 6; Plate II-2, 8-9; Plate III-9), mollusks
including pelecypods and gastropods (Plate II-5; Plate III-3), small benthic
foraminifera (Plate I-7; Plate II-9; Plate III-8; Plate IV-8), and planktonic
foraminifera (Plate IV-3), which were identified only from the limestones collected
in Malabing. The paleoecological and paleoenvironmental significance of these
bioclasts are shown in Table 2. Some limestone samples collected from Malabing and
Dilaping also contain detrital mineral grains such as pyroxene, plagioclase and K-
feldspar. Plates I-IV show the different limestone textures and the bioclasts observed
under the microscope.
Table 2. Paleoecological significance of common fossil groups in the Capisaan
Limestone Member of Sta. Fe Formation. (Patterned after Foronda and Schoell, 1987).
Fossil Group
Paleoecology in Carbonate Environments
Coralline Red Algae
Usually normal marine; tidal zone to 250 m; usually <25 m
water depth; open marine platforms and bays with banks or
reefs, shelf slopes.
Benthic
Foraminifera
Widely distributed in reef complexes. Abundant miliolids on
back-reef. Encrusting forms locally bind sediments in forereef
and back-reef and attach to large organic skeletons. Arenaceous
forms in lagoonal, back-reef, and shallow neritic deposits.
Planktonic
Foraminifera
May be widely distributed in reef complexes. Abundance of
planktonic foraminifera suggests open marine conditions.
Colonial Corals
Shallow, sunlit, tropical to subtropical, normal marine waters. A
close relationship exists between the growth form of corals and
the environments where they thrive.
Ostracods
In reef complexes, ostracods are most abundant in lagoons where
salinities are slightly lower than normal.
Gastropods and
Pelecypods
Most megaforms in shallow waters.
Echinoderms
Mostly below littoral zone, especially where waters have normal
salinities.
Garas et al. (2019)
48
Figure 7. Macrofossil components of the Capisaan Limestone Member of Sta. Fe
Formation in Kasibu: (a) pelecypod, (b) large benthic foraminifera in the lagoonal facies
of the limestone, (c) gastropod, and (d) finger coral fragments in a bedded limestone.
Bioclastic wackestones (Plate II-5-8; Plate III-1-6; Plate IV-4-6) are well-
distributed in the study area with good representative exposures in Capisaan, Wangal
and Malabing areas. These exposures are bedded and contains high diversity of
poorly sorted bioclasts. Fragments of large benthic foraminifera, echinoid spine,
mollusks, corals and red algae are embedded in 40-70% micrite. These limestones are
interpreted to have been deposited in a shelf lagoon proximal to the main reef build-
up.
Few exposures of foraminiferal grainstones (Plate I-3-4; Plate III-7-10; Plate IV-
1-3) were observed in Malabing. Foraminiferal grainstones consist of less diverse
bioclasts predominantly large benthic foraminifera and occasional planktonic
foraminifera. Hand specimens are defined by chalky/silty texture. The percentage of
micrite and occurrence of occasional planktonic foraminifera suggest that the
grainstones were deposited in a lagoon environment with open marine influence.
Garas et al. (2019)
49
The grainstone-packstone units (Plate I-1-2, 5-10; Plate II-9-10; Plate IV-7-10)
are composed of closely-packed, clast-dominated limestones. Bioclasts are
represented primarily by coral fragments, red algae, benthic foraminifera, and
echinoid spines. These units were observed in Brgys. Cabinuangan, Capisaan and
Dilaping. Reef rudstones (Plate II-1-4), characterized by fragmented finger corals and
red algae, were found in the same localities. These units represent the reef flank/fore
reef slope area associated with a high energy depositional environment. It is
characterized by the abundance of coarse reef-derived bioclasts including coral, red
algae, echinoid spines, and benthic foraminifera. Observed algal encrustations in the
samples support high energy conditions in a shallow marine environment.
Large Benthic Foraminifera and Age of Limestone
Large benthic foraminifera were used to determine the age of the limestone
member of Sta. Fe Formation in northeastern Kasibu. Species observed in the samples
include Sphaerogypsina sp. (Plate III-2), Operculina spp. (Plate III-7; Plate IV-9),
Cycloclypeus spp. (Plate IV-2, 9), Lepidocyclina formosa (late Early Oligocene to
Early Miocene), Lepidocyclina inflata (Early to Middle Miocene), Lepidocyclina
(Eulepedina) richtofeni (late Early Oligocene to Early Miocene), Lepidocyclina spp.
(Plate I-9; Plate III-1, 4, 6-7, 9-10; Plate IV-4, 6-7,10), Flosculinella cf. F.
botangensis (early Early Miocene to Middle Miocene; Plate II-4, 6-7), and
Miogypsina sp. (Early Miocene to Middle Miocene; Plate III-6, 8; Plate IV-5). Based
on the occurrence and assemblage of these large benthic foraminifera, an Early
Miocene age is established for the limestone member of Sta. Fe Formation. The result
suggests that the limestone unit in Kasibu is younger than the turbiditic/clastic
member of Sta. Fe Formation (MGB, 2010). Since the relationship of the limestone
member with the clastic member was not observed during the fieldwork, it is
recommended to conduct further mapping and stratigraphic studies. The age of the
turbidite/clastic member should also be re-evaluated. It is proposed in the present
study that the limestone member of the Sta. Fe Formation be recognized as a formal
lithostratigraphic unit and be named Capisaan Limestone Member after the exposures
in Barangay Capisaan.
Capisaan Limestone Member
Lithology: Limestones (wackestones, packstones, grainstones
and floatstones); see detailed description in the
previous sections.
Type Locality: Brgy. Capisaan, Kasibu, Nueva Vizcaya
Stratigraphic Relations: Unconformable over the foid andesites of the
Mamparang Formation. Stratigraphic relationship
with younger units not established.
Garas et al. (2019)
50
Distribution: Brgys. Malabing, Wangal, Dilaping and Capisaan,
Kasibu, Nueva Vizcaya
Age: Early Miocene
Thickness: 250 m (based on exposed section; data from 2011
Geology 170 Class of UP NIGS)
CONCLUSIONS
Petrographic and paleontological analyses of the limestone samples from Kasibu,
Nueva Vizcaya revealed the following information:
(a) Petrographic analysis of the limestone samples identified the following
textures: (a) wackestones (mud-supported with >10% bioclasts); (b)
packstones (grain-supported containing less mud than wackestones); and (c)
grainstones (grain-supported and lacks mud). Floatstones samples are also
present in Capisaan area, however, no petrographic analysis was conducted
for these samples. The grainstone-packstone units in Cabinuangan,
Malabing, Capisaan, and Dilaping, and the reef rudstone/floatstone units in
Capisaan and Wangal represent the foreslope/reef flank environment.
Bioclastic wackestone units in Capisaan, Malabing, and Wangal, and
foraminiferal grainstones units in Malabing represent a shelf lagoon
environment with open marine influence.
(b) Based on the occurrence of several species of large benthic foraminifera, an
Early Miocene age is assigned for the limestone unit; and
(c) The limestone unit in Kasibu, Nueva Vizcaya is formally proposed to be
named Capisaan Limestone Member of the Sta. Fe Formation.
ACKNOWLEDGEMENTS
The authors would like to thank OceanaGold Corporation (through Mr. Cecilio
Bautista and Mr. Ariel Panol) for the support during the fieldwork and for allowing
us to publish the data. We would like also to thank the Municipal and Barangay
officials and the people of Kasibu for the hospitality during our 3-week field mapping
activity in the area. Our classmates in the Geology 170 Class of 2011 are also
acknowledged for their contribution in the establishment of the general stratigraphy
and geology of the area. Ms. Elsa Y. Mula, paleontologist of Petrolab-MGB, for her
valuable help in the identification of foraminifera. Ms. Maria Ina Katrina D. Bondal,
geologist of Petrolab– MGB, for editing some of the figures in the manuscript. The
Nannoworks Laboratory at UP NIGS for the use of the microscopes and Mr. Renato
Bautista for the thin section preparation. The authors are grateful to Mr. Rolando E.
Garas et al. (2019)
51
Peña and Dr. Leopoldo P. de Silva, Jr. for their valuable comments and insights that
improved the manuscript.
REFERENCES
Billedo E.B., 1994. Geologie de la Sierra Madre Septentrionnale et de l'Archipel de
Polillo (Ceinture Mobile Est Pacifique), PhD Thesis. Universite Nice-
Sophia, Antipolis, France. 215 p.
Carozzi, A.V., Reyes, M.V., and Ocampo, V.P., 1976. Microfacies and Microfossils
of the Miocene Reef Carbonates of the Philippines. Philippine Oil
Development Company, Inc., Special Publication No. 1., 80 p.
Dunham, R.J., 1962. Classification of carbonate rocks according to depositional
texture. In Ham, W.E. (ed.), Classification of carbonate rocks, American
Association of Petroleum Geologists Memoir, 108-121.
Fernandez, M.V., 1996. Sediment Facies, Age and Depositional Environments of the
Labayug Formation, Sison, Pangasinan, MSc Thesis. National Institute of
Geological Sciences, College of Science, University of the Philippines.
Th/CS-GE-96-50.
Foronda, J. and Schoell, W., 1987. Microfacies Types of the Binangonan Formation,
Antipolo-Teresa, Rizal Province. Journal of the Geological Society of the
Philippines 41, 40-78.
Fournier, F., Montaggioni, L., and Borgomano, J., 2004. Paleoenvironments and
high-frequency cyclicity from Cenozoic South-East Asian shallow-water
carbonates: A case study from the Oligo-Miocene buildups of Malampaya
(Offshore Palawan, Philippines). Marine and Petroleum Geology 21, 1-21.
Griffiths, S., Holmes, M., and Moore, J., 2014. NI 43-101 Technical Report for the
Didipio Gold/Copper Operation, Luzon Island, Philippines (S0037-REP-
020-0), 219 p.
https://nuevavizcaya.gov.ph/nueva-vizcaya-tourism/points-of-interest/capisaan-
cave/
Javelosa, R.S., 1994. Late Pleistocene Tectonism in the Bohol Arc System. Active
Quaternary Environments in the Philippine Mobile Belt, ITC Publication, 28-
49.
Mines and Geosciences Bureau (MGB), 2010. Geology of the Philippines, 2nd
edition. 532 pp. Mines and Geosciences Bureau, Quezon City.
Metal Mining Agency of Japan – Japan International Cooperation Agency, 1977.
Report on Geological Survey of Northeastern Luzon. 325 p.
Peña R., 2008. Lexicon of Philippine Stratigraphy. Geological Society of the
Philippines, 364 p.
Taylor, I., 2013. Runruno Project Malilibeg South Resource Nueva Vizcaya
Province, Philippines. 20 p.
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At least 3 to 5 keywords should be provided below the abstract.
6. Introduction
This section must provide an overview/background and the objectives
of the work done.
7. Methodology
This section details the methods and materials used in the study. The
methodology presented should be replicable by other researchers.
8. Results
Data generated in the work should be discussed and presented in this
section.
9. Discussion
This section presents the significance of the study done.
10. Conclusions
This section provides a summary of the highlights of the study.
11. Acknowledgements
Individuals or institutions who/which helped in the conduct of the
study can be acknowledged here.
12. References
References in the text should appear as, for example, (Claveria and
Fischer, 1991) or ‘according to Claveria and Fischer (1991)”. If more
than two authors are involved, their work should be referred as e.g.,
“De Leon et al. (1991)”; all authors should be named in the references.
References should be listed as follows:
Fernandez, H.E. and Damasco, F.V., 1979. Gold deposition in the
Baguio Gold District and its relationship to regional geology.
Economic Geology 74, 1852-1868.
Park, C.F. and MacDiarmid, R.A., 1964. Ore Deposits. W.H. Freeman
& Co., San Francisco and London, 475 p.
Pearce, J.A., Lippard, S.J. and Roberts, S., 1984. Characteristics and
tectonic significance of supra-subduction zone ophiolites. In Kokelaar,
B.P. and Howells, M.F. (eds.), Marginal Basin Geology, Geological
Society London Special Publication 16, 77-94.
iv
13. Figures and Tables
Figures should be presented in a separate word file and not within the
text; one figure each page with figure numbers (e.g., Fig. 1). Tables
must also be saved as a separate file. Captions for figures and tables
should be added after the reference list. Please ensure that each figure
and table has a caption.
14. Proposed Reviewers
The corresponding author is requested to provide the names of 3
possible reviewers (international and/or local).
D. Submission, Review and Acceptance
A cover letter addressed to the Editor-in-Chief should be submitted with the
manuscript. Submissions can be emailed to jgsp@geolsocphil.org. All
submissions will be initially assessed for suitability by the Editorial Board.
The scientific merits of the submitted manuscript will then be peer reviewed
by two independent experts. The reviewers will be given 30 days to complete
their evaluation of the paper. The author(s) will be asked to submit their
revised manuscript within 30 days to address the comments of the reviewers.
Additional queries can be directed to the:
JGSP Editorial Board
Geological Society of the Philippines
National Institute of Geological Sciences,
University of the Philippines
Diliman, Quezon City 1101 Philippines
Email Address: jgsp@geolsocphil.org
