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PAEC (C) IB 81012 0CT1319W FANAY CARBORNE RADIOMETRIC AND GEOCHEMICAL SURVEYS /
-by
GABRIEL SANTOS JR.
PHILIPPINE ATOMIC ENERGY CO MISSION
and
CAROL SAMONTE, ROMEO ALMEDA, ROLANDO RANES, JOSE SALVADO, and JESSE MIGUEL
BUREAU OF MINES AND GEO-SCIENCES
September 1981
Philippine Atcmic Energy Commission Don Mariano Marcos Avenue Diliman, Quezon City SC1L'«» *<•'•-. Lit******
OCT 13 19* PAEC (c) IB 81012
PANAY CAREORNE RADIOMETRIC AND GEOCHEMICAL SURVEYS
by
GABRIEL SANTOS JR.
PHILIPPINE ATOMIC ENERGY COMMISSION
and
CAROL SAMONTE, ROMEO AIMEDA, ROLANDO RAMS, JOSE SALVADO, and JESSE MIGUEL
BUREAU OF MINES AN J GEO-SCIENCES
September 1981
Philippine Atomic Energy Commission Don Mariano Marcos Avenue niliman, Quezon City PAEC («) IB §1012
TABiiE OF CONTESTS
Page
Abstract 1
Introduction * 2 Purpose .....^ Location and Accessibility 4 Geology 1...... 3 Structure .....6 Radiometric Carbornu Survey ...... 7 Geochemical Survey 8 Resulta and Discussions 9 Recommendations ...... 10 Acknowledgement ...... 11 References 12 PABC (C) M »t&1f
UST OP TABLES AW) FIGURES
Table 1t Stratigraphy of Iloilo Basin
Figure 1t Geology of Panay and Guimaras Islands
Figure 2 s Radioactivity Map of Panay and Guimara* Islands, Showing Uranium Contents in Stream Sediments. •-lilliri-'- "- ••••*•-'•'-">-"•.--<«•-• .f*.W«1»3>»*"VnTV»»>ri-. '
PARC (C) IB 81611 Page 1
PANAY CARBORHB RADIOMETRIC AHB GBOCm'lCiiL STOVKTS
by
Gabriel Santos Jr.
Philippine Atomic Energy Commission
and
Carol Samonte, Romeo Almeda, Rolando Ranes, Jose Salvado and Jesse Miguel
Bureau of Mines and Geo-Sciences
ABSTRACT
A carborne radiometric survey and stream sediments collection were conducted in Paray and Guimnras Islands. An area in Nabas, Aklan, situated in the northwestern tip of Panay (Buruanga Penin sula) which indicated 2 to 5 times above background radioactivity was delineated. Uranium content in the stream aed.ment samples collected from Buruanga Peninsula was generally higher than those obtained in other parts of the island. Radioactivity measurements and uranium content in stream sediments were found to be within background levels. It is recommended that follow-up radiometric and geochemical surveys be undertaken in Buruanga Peninsula and additional stream sediments samples be collected in Panay to ac hieve better sampling density and coverage. PAEC (C) IB 81012 Page 2 IHTRC SUCTION
Panax island is considered prospective for uraniua on the basis of the presence of Miocene sedimentary rocks in the lie- ilo Basin which is bordered In the west by volcanic rocks and agglomerates; and tuffs in the southwestern part and pre-Tertiary metamorphic rocks in the northwestern part of the island. On the east, the basin is bounded by the pre-Hiocene diorite and volcanic rock assemblage (Francisco, 1955* Santos, 1968). It is believed that the pre-Tertiary rocks are possible source rocks of uranium that may be concentrated in the Iloilo Basin or in themselves could serve as possible host rocks for uranium mineralization.
PURPOSE
A cerborae radiometric survey was conducted to detect the level of radioactivity in Panay islnnd and delineate areas with amomalous radioactivity, A reconnaissance stream sediment sampling was also carried out to determine the -.ranium distribution in the
island.
LOCATION AND ACCESSIBILITY
Panay island is located in the western part of Central Phili ppines and is about 300 km, southeast of Manila, There are four provinces within the island, namelys Iloilo, Aklan, Capiz and
Antique. PAEC (C) IB 81012 Page 5
The principal cities in the north are Kalib© in Aklan and
Roxas in Capiz while in the south, Iloilo City is the major entry
port. Kalibo and Iloilo have regular airline services from Manila*
Immediately southeast of Panay is Guiaaras island which could be
reached from Iloilo City by a 15-ainute ferry boat.
GEOLOGY
The geology of Panay has been studied by Corby, et al, 1^51
and elaborated in more detail by Francisco, 1953f Capistrano and
Magpantay, 1956j and Santos, 1968. The- island has three principal
physiographic features, the Iloilo Basin tsrhich is found on the cen
tral part of Panay and two major mountain ranges in the west and in
the east. The mountain ranges are called the Western Cordillera and
the Eastern Cordillera. The Basin apparently opens to the Sibuyan
Sea in the north and open3 to the Oulmaras Strait in the south. The
geology and stratigraphy of the Iloilo Basin have been studied in detail
by Santos, 1968, among others. Shown is Table 1 is the stratigraphy of Iloilo Basin, Santos, 1968,
Table 1. Stratigraphy of Iloilo Basin
Western Hollo Eastern Iloilo
Rock-Stratigraphy Sedimentary Rocks Rock-Stratigraphy
Units Age Unit
Alluvium Quaternary Alluvium \'>™c sf.%^"" ->n!^*r!> n?"%^ ^"^ri^-^t^^L'*"'^ ^'^' .av,'^'s^-t^ ^*.7 ^ -u Af,^ .-^\° ** .* -'r *> •* f^^.'^^f f n '»••"-'? •; -t r'" ^--mw*" - • • ••* m'fm"
•¥•" PABC (C) IB 8tO$2 Fftf« 4
.—_._____——.—»—Unconformity
Cabatuan Formation Pliocene to Cabatuan Formation
Pleistocene
Ulian Formation Pliocene tflian Formation
Iday Formation
Tarao Formation Late Miocene to Mngle Formation
Barlp Pliocene
Singit Formation Late Miocene
-Unconformity —
Middle Miocene Passi Formation
Cabatuan Bike Igneous & Meta-
morFvic Rocks
Sewaragan Complex Middle Miocene Bayaso Volcanics
Member
Basement Complex Fre-Oligocene (?) Salngan Member
Pre-Tertiary Basement Complex
The thickness of the sedimentary rocks on the western flank
of the Basin ranges from 3»680 to 7,700 meters while on the eastern
flank, the thickness ranges from 1,930 to 2,640 meters, Santos,
1968, considers the Tubungan-Alimodinn-Kaasin area as prospective
for petroleum and gas,
Panay Uranium Potential
Certain rock formations of the Iloilo Basin are considered
possible host rocks of uranium, especially the Miocene Singit,
Dingle and Passi Formations In particular, the sandstone and
limestone member of these sedimetary formations are considered
worthwhile study areas. PAIC (C) IB 81012 Page 5
The possible source rocks *»f these rock formations are the pre~Oligocene or pre-?ertiary Basement rocks consisting of igneous and metamorphic rocks* In Buruan^a Peninsula, in the northwestern tip of Panay, the basement rocks include schists, chart, metavol- canics graywacks, quartaite and oarblei2ed limestone (Francisco, 1^55),
Along the Iloilo-Antique boundary, basic rock types predominate con* sisting of basalts, volcanic breccias, agglomerates and minor sexv pentines and quartzitc. The Miocene Sara dlorite among others in northeastern Panny is believed to be a possible source rock of Pass! and Dingle Formations,
It may be noted that the igneous and metamorphic rocks in the western and eastern Cordillera are also considered possible favo» rable uranium host rock3, in particular,the Sara diorite and basement rocks of Buruanga Peninsula,
STRUCTURE
According to Santos, 1968, the structural development of Panajr
closely follows the gecsynclinr.l theory of sedimentary basins, Corby
defines the Iloilo Basin as r. broad structurnl depression trending north~3outh and bounded by highlands on the west, north and northeast.
Movements in the geosynclinc caused by accumulated sediments has pro
duced folds, anticlines, synclinos Tiolaa Tult Zone near the Antique-
Iloilo boundary and numerous secondary faults. Generally, the struc
tural trends follcws a north-south orientation and the basinal deve
lopment is relatively symmetrical. Shown is fig, 1 is the geology of
Panay and Ouimaras, (Vrom Geological Map of the Phil,, 1965. Bureau of Mines), : v., _!-„;v.--y.Vaa**.^^^-.''i rM7t^*H&^*!&&»i&
PAEC (G) IB 81012 Page 6
RADIOMETRIC CARBORNE SURVEY
The radiometric ccrborne survey was conducted along pass able national roads in Panay. The roads in the central part of
Panay, within the Iloilo Basin, are more numerous than those on the western part of the island* In Antique, most of the roads are limited to the coastlines. The road density of Fanay is about 0.1 km/sq.km.
Two 1:250,000 scale maps were used. One of the maps published by Phil. Coast and Geodetic Survey, edition 2, Feb. 1974 and the other was obtained from the Planning and Dosignning Division of the
Ministry of Public Highways, Region VI, at Iloilo, Some discrepan cies were noted in both maps, such as, missing roadaj
GETCTTEKICAL C-"?TEY
Stream sediments weighing about 1-2 kg, wore collected along accessible streams and rivorc intersected by the Panay national roads. The sediments 7/ore sun-dried and prepared in the base camp in Iloilo City by screening and separating the minus 80 mesh frac tion. The samples were sent to tho PA^C laboratory for uranium ana lysis. The method of Smith and Lynch (1969) employing a Jarell-Ash model 26-000 fluorameter was used in analyzing for uranium. The limit of detection of the method was about 0,2 ppm uranium. The background and threshold values of the uranium contents in stream sediments vere computed using the method of tepeltier (1969), The geochemical survey was undertaken after the completion of the car- borne radiometric survey and took about a month to finish. PASC (C) IB 81012 Page 7
RESULTS AND DISCUSSIONS
Radioactivity measurements
A total of 1,06^ km. of reads were traversed representing about
95"^ of the passable national roads, including Guimaras island* Ins trumentation used included the Geometries GPX-110 sodium iodide 4" x 6" crytal detector coupled to a I'cPhar TV-5 spectrometer. The detector was placed in the riof of the vehicle while the spectrometer measure ments were read inside the vehicle. Radioactivity readings were con- tinously monitored while- the vehicle was traveling. Only total radio activity counts were recorded, Reading ranged from 700 counts per second to 9,000 counts per seconds (cps). Average reading was about
1,500-5,000 cps. Low reading- (700-1,100 cps) were obtained from Bacao
to Nabns and from Sara to Paintnn in northern Panay, Moderately low values (1,500-3,000 cps) were recorded For most of the Iloilo Basin
and along the western coast of Antique, The survey was conducted from
Sept. 2-8, 197?.
Anomalous radioactivity readings (5»000-9j000cps) were measured in Buruanga Peninsula, in particular,along the road from Linderof
Santander to Kasag and midway between Buruanga and Malay, The
highest readings were obtained in Barrio Bizal and Unidos along a
300 meters section of reddish-yollowish sedimentary rocks which wer6 altered by hydrothermal solction. In Santander-Masag road, the rocks encoutered were mainly buff colored limestone overlying grayish basalt/ andesite. Shown in Fig, 2 is the radio-activity map of Panay and Gui- mara3 islands. PAEC (C) IB 81012 Page 8
The limestone (K») was dated Pliocene-Pleistocene while the
Intrusive ($1) was intra-Kiocene. This age relationship of the rocks* in the area suggested that the intrusives (aiorite?) were possible source rocks of urr.niuo and could have contributed sedi ments in the nearby sdimentary rock sequence. The intrusive (Nl)
Situated between Libertad and Pandan was believed prospective for uranium.
TTrSnium in stream sediments
A total of 165 stream sediments samples were collected and ana~ lyzed. Shown in Pig. 2 is the radioactivity map of Panay and Gui- maras islands showing uranium contents in stream sedimetrts. The background and threshold values for uranium i.-. stream sediments were
less than 0,2 ppm (NT)) and 0.4 ppm, respectively. There was general
agreement between above background radiometric readings and high uranium values in stream sediments in the Buruang?r area. The potential of the basement complex including marbleized limestone and quartzite in Buruanga Peninsula wa3 still unknown
but the rock suite was considered favorable for possible uranium
mineralization. The southern part of Ouimaras which was underlain by Pliocene** Pleistocene limestone, Oligocene volcanics and Miocene diorite rocks
was also surveyed. Measurements ranged from 1,800 to 4»000 cps and no
anomalous radioactivity readings were recorded. Though not all of Ouimaras was covered by the survey, it was felt that the island has low potential for uranium. PAEC (C) IB 81012 Page 9
RECOKKEHDATIOKS
On the basis of favorable geology and anomalous radioactivity, follow-up geschemical/radiometric and detailed geologic surveys in Buruanga Peninsula are recommended. The region to be surveyed should include the area within the circumferential road along the coastline of the Peninsula and bounded bk the Nabaa-Pandan road in the east.
It is further recommended that about 85-100 samples more should be collected in Panay at selected location to provide better sampling density (1 sample/20 3q, km.) and coverage. PAfC (C) IB S1012 Page 16
ACKH0WU5DGEKBNT
The authors wish to ackowledge the encouragement given by
PAEC Commissioner Zoilo II, Bnrtolome and Bureau of Wines and
Geo-Sciences Director Juanito C, Fernandez during the conduct of the survey.
The uranium geochemical analyses were- done at the Huclear Fuels
Research Division by B. Villamater, PABC (C) IB 81012 Page 11
REFERENCES
Francisco, F.U., 1955» The pre-Tertiary rock3 of Buruanga Penin sula Panay Island, Philippine: Proc. Eight Pacific Science Congress of the Pacific Science Association, pp, 482-494,
Santos, P.J., 1968, Geology a*id section measurements in Iloilo
Basin, Panay Island, Philippines: ?he Philippine Geologist,
vol. 22, no, 1, lianila,
Corby, et al, 1951» Geolopy and oil possibilities of the
Philippines: BAICR Technical Bull, No, 21, 3&3 p, Manila,
Capistrano, P.M. and ifegpantay, A.L., 1958, Geology and mineral
resources of the southern segment of the eastern range of
Panayj The Philippine Geologist, vol. 13f no, 1, pp. 1-21. ^s S I B U Y A N S £ A
| SECTION 2
s> I i2"00' V^"^-^"^:
SECTIO
ww i**m^ti>2j&&0^? 15'- I SECTION 6 LEGEND 11*00- SEDIMENTARY AND METAMORPHIC ROCKS • • '"'•"•. n rtctnf Alluvium, f luviotlle IsCMtrin* 0*4 beach deposits N 0, Miocene Marine and terrestrial sOditMnfs 3 + 'leistocene J|P «V.«'0C,,,• "•''•• clotlics overloln by „ »2 Miocen3 i e tutfoceous sediments yiiqoctn* Morfne deposits, woe ties and shales. ?m », Miocene 3ligocene Wockes and sholos P«2 Creroceouf - Groywocko ond matomorphostd shole Kpg ;Poleogone * Interbadded .with voiconics or pyroclosries. Cretaceous Groywocke • (hoi* sequence interbeddsd • 45'- i with epllltes. •c feldspothlc ond mica schist and p fir III f •»•»#•- *pS*M*' Pmtltrn i|#«4** fff*#«r«*f IwtfMeV • i .• IGNEOUS ROCKS sem,£. 1250,000 ,~*~- I SECTION 7 | wSmmmmmmfm •''W.J . j^- F«6;NQi CD £2r LC: t 230,000 S2» » SECTION 8 **. IWMMP GUIMARAS TJF i 4<. ^ w s s« J i men 1;• pligocene Marine deposits, wockes and shales. ^ "t (VMocene y Pa. JDNgoctne Wackes and shales. ^Cretaceous - Groywacke and metamorphosed shale Kpg Poleogene interbedded .with ,10 iconics or pyroclosries Cretoceous Groywacke - shale sequence interbedded 45'- <0 with spilites. Basement Co-nplex _,.... ._... ., BC (Pre-Jura isle ) Undifferentiate amphiboKte, quortzo- feldtpathlc and mice schist and iy.M 1 * • • • • • > Pattern dinotes limestone bodies. Efcr I'I CO IGNEOUS ROCKS NI 'Noogene Intra - Miocene Btoitz diorlte Pgl Paleogene Quartz diorite Cretoceous Undifferentiated eltromafic ond UC Poteooooe mafic plutonic rocks. VOLCANIC ROCKS Pliocene - Non-attiva cones, nyreMme andesite. ov Quaternary EH xf- v v v | Pa2 Ollgocene Kerotvofcyr* and «ntf«*fte flow*. 0) v v GEOLOGIC SYMBOLS ••> VI .U ^' - Fornoffonal boundary. Jr^ - Anticlinal oslo j^ - Synclinal Mis ''* - Hlffft onfr» faolt, tasked wfcaro \riktt**.-'4l - Tkvret fnolt, fitftwf wt#»» tnttrratti '•a*-faafj* oft avarr!*!** •»«•, . • 45' SECTION 9 T I22°00 122°15' -l3°0O aontcAY iSLnmo Rixal (NO >4) S9 • _»•»> FI0.2) i y / s A 02 r (tt4) X J*f«r ! M' \ ' tianiudro- MOUNT 6UBULMI ,«X2) • ana, (Of) i*ia*i*i twJ J caei (*» 0* 1-12*49' as fmjt £ VMD) M«Ui« P A HI D A HI MAY UW>) / 23 / 2) f MOUNT untIo 0.7 ^~^-/T, "^ X2) V ^0«»«IT\»«I«|(| \5 •WWT^ML^BHC S««fci4t« SECTION 1 J >4) /MOJWT 4Mi»r N yteuNT MMHTMA VI fK. fS Bit* i-I2'30' j (MOOVT roeream t^y 1 X0.4) Cui«; \ ,W~ >4) \ZZ° 30 !22°45 a SI B U Y A IH SEA | SECTION 2 KAUBO (0.2) 4 . (TOXAS ~vc: CAM BAY V < ^srANDAlTISLWO I DUill, 1.2 OS Alt«M [Dalehan I .1.1!• :X (*or > 1 Sapwn \D*p4sa*n M ^ '" V N #(02) /• \ ^32 (ND) »2) z' MambuMo ^ Sigi ( 4 Jjrnindi ^Sunj* (ND) 1 / Ma-*yori £'J / mHpjfnimnM i °45 23o00' I23''15' -20° PHILIPPINES 15° -K>° -59 I20c 125° INDEX MAP P I SECTION 3 12° 15' 10 SECTION k o UNO) *>', T-"1. *?-' / .A 1 --••• ~/~ r l.5 V fBeticon J J» P ( y,-^'\ ' v^. . MOUWT TAMBARA [13 7 ; San PWd ^**!? / rz *>v. // / ./ /V3 SAM J0SB r •ll°45 r / rJ FIGURE 2 SCALE. I! 250,000 10 IS 20 25 km*. SA« jo: -11° 45" -11° 30" P A N A Y i sECTTBH'?J RADIQACTIVr SHOWING U '•* -£>••* •;-y OF SHOWING URANIUM CON /t* ./>- F;,. J,f* + *» FIGURE 2 SCALE. I. 250,000 10 IS 20 25 kms. EXPLANATION 2.5 - Radioactivity Counts Per Second (X 1000) Anomalous Radioactivity - Greater than 4,000 cps CARBORNE RADIOMETRIC SYSTEM USED! Gamma Roy Spectrometer- MCPHAR TV-5 Crystal Detector - Geometries GPX - IK) MOUNTED ON 6" dia. X 4" thick Nal(TI) \ THE ROOF OF AVERAGE VEHICLE SPEED - 30 KPH (0.2)- Uranium content in parts per million. j SECTION 9 j (ND)- Not detected, lees than 0.2 ppm U.