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REPORT KO. IAEA-R-94S-P"

RECONNAISSANCE GEOCI , I£ TITLE

Geochemical activation analysis and geophysical surveys in Bohul, , (part of a coordinated programme of îeeearch on the use of nuclear techniques in geochemical and geobotanical prospecting for minerals) FINAL REPORT FOR THE PERIOD 1 November 1970 - 30 November 1972

AUTHOR(S)

G.S.Santos

INSTITUTE

Philippine Atomic Energy Commissioin Chemistry Department , Philippines

INTERNATIONAL ATOMIC ENERGY AGENCY CERTIFIED BY: DATE °Ctte 1972 tu- RECONNAISSANCE GEOCHEMICAL ACTIVATION ANALYSIS SURVEY IN DAVAO, MINDANAO ISLAND FOR SCANDIUM, COBALT AND IRON

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Geochemical rec< Davao del Norte and '. lippines. The area i meterB. A total of ! samples were collects were determined using copper was analyzed s and in part, by atomâ Gabriel G. Santos Ofelia T. Falabrica Statistical tree rate correlation betm Melinaa S. Yulo were obtained for Sc/ areas. In Davao del Nor anomalies were locate were found in stream creeks. In mostly restricted to deposit is suspected is clearly indicated along the creek. The Philippine Atomic Energy Commission values which is appar Philippine Atomic Research Center Diliman, City copper anomaly and a August, 1972

CERTIFIED EYi o

A coordinated in geochemical-geo ABSTRACT by the Philippine Atomic Energy Agen the Research Contr Geocheinical reconnaissance rock surveys were conducted in Savso del Norte an» and Davao del Sur both in Mindanao Island, Phi- tigated. The pires lippines. The area of coverage is approximately 700 square kilo- reconnaissance sur meters. A total of 275 rocks and 3690 soil and stream sediment approximately 700 samples were collected and analyzed. Scandium, cobalt and iron were determined using instrumental activât:on analysis while copper was analyzed mostly by the colorimetric biquinoline method Background and Sec and in part, by atomic absorption spectrometry. A geochemical Statistical treatment of the data showed that there is mode- , Mindanao It rate correlation between scandium and cobalt. Poor correlation Santos and Palabrd were obtained for Sc/Cu, Sc/Pe, Co/Cu and Co/Pe for both project different topograi areas. the suitability oi In Davao del Norte area, a cluster of Sc, Co, Pe and Gu of two entirely di anomalies were located in upper Manat creek. Copper anomalies trasting regions, were found in stream sediments from Saraban and Matagdongan hills. Davao del ] creeks. by rugged topograp]

In Davao del Sur, cobalt, scandium and copper anomalies are Rock, soil an mostly restricted to Sangay creek. A possible economic pyrite rocks were analyze deposit is suspected in the Tecal creek area. This mineralization neutron activation is clearly indicated by the presence of several iron anomalies leeted samples by along the creek. The pyrite deposit may contain some copper dium, cobalt, iron values which is apparently indicated by the presence of a rock Their geochemical copper anomaly and a few soil anomalies. diagrams. When tl Teen copper and ti the presence of cc the area of inters possible sites whi î. .1-- :?••.-. .'•« •.-•^.a,jJ..1;;.v;.-*j.-,-^-.-i-.~- o e

INTRODUCTION

could be applied. The A coordinated program on the use of the nualear teohniques ting for major copper in geochemical-geobotanical prospeoting for minerals was oonducted by the Philippine Atomic Energy Commission and the International Project Area Atomic Energy Agency from November, 1970 to December, 1972 under the Research Contract No. 948/RB. AS per agreement, two areas in Davao del Norte and Davao del Sur in Mindanao island were inves- tigated. The present work is concerned with the geochemical reconnaissance survey done in the Davao areas covering a total of approximately 700 square kilometers (Figures 1 and 2).

Background and Scope of the Project

A geochemical reconnaissance survey was oonSucted in Northern Bohol» Mindanao Island for copper, scandium, cobalt and iron by Santos and Falsbrica, (1972). A similar survey of an area with different topography and vegetation was deemed necessary to teat the suitability of the technique previously employed in the study of two entirely different regions» Bohol and Davao are two con- trasting regions. Bohol is characterized with grassland rolling hills. Davao del Norte and Davao del Sur are both characterized Regional Geology by rugged topography with tropical forest.

Rock, soil and stream sediment samples were collected. The rocks were analyzed for scandium, iron and cobalt by. instrumental neutron activation analysis. Copper was determined in the col- lected samples by colorimetric method. The distribution of scan- dium, cobalt, iron and copper in the country rocks was studied. Their geochemical relationships were compared using correlation diagrams. When there were significant correlation obtained bet- ween copper and the elements, and. when further, substantiated by the presence of copper anomalies in soils and stream sediments, Physiography the area of interest could be pin-pointed. These areas would be possible sites where more detailed conventional prospecting taethods

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- 2 - respectively. The p could be applied. The technique is a semi-direot way of prospec- fined arbitrarily by ting for major copper districts. turan area averages rages about 300 mete Project Area in both areas. The both areas. Stream The.investigated areas lie at approximately 126°1«-126°8I East longitude and 7°25I-7°32I North latitude; and 125O52'-125837' per kilometer on the East longitude and 6°14'-6O22I Worth latitude. The former is in tricts for the most the municipality of , Davao del Horte while the latter dense tropical growt is within Malita , Davao del Sur. Both areas are in the island of Mindanao in southern Philippines. The municipalities of Nabun- SAMPLING turan and Malita are about 90 kilometers northeast and about 100 kilometers southeast respectively, of , The project The rock, soil area in Davao del STorte is approximately about 500 sq. km. and is along a Brunton-taps located southeast of the town of Habunturan and about 8 km. north meters. Only fresh of an abandoned copper-gold mine. The investigated area in Davao pies were obtained del Sur is about 200 sq. km. and approximately 7 km. southwest of pljjLng point of stret the town of Malita. The project areas could be reached by feeder the opposite banks and logging roads and foot trails leading to the town of Nabuntu- ments consisted esse ran and Malita. ic matters. More th stream sediment samp Regional Geology ly 500 sq. km. in Na samples and more tha The general geology of the Davao project area are described ted from Malita, Dav in the "Geological Map of the Philippines", (1963) prepared by the Philippine Bureau of Mines, The areas are underlain by basaltic- Drying of the E andesitic rocks and minor emounts of metavoloanics and sedimenta- placing the Bamplës ry rocks, and small dioritic masses. The relative age of the rocks ner. The dried sami ranged from Oligocène to Upper Miocene. It is estimated that more less Bteel screen. than 9Ofo of the project areas are underlain with basaltic-andesitic «nelyaia The rook E flows. analysis. ' ,

The déterminât: Physiography were done by instrtu Nabunturan and Malita lie within the Pacific Cordillera and rock standards, BCR Buayan Valley physiographic.subdivision.of Central Cordillera,

o -3- respectively. The physiographic provinces of Mindanao were de- fined arbitrarily by Ranneft et al, (i960). Relief in the Nabun- turon area averages about 500 meters, and in Malito relief ave- rages about 500 meters though locally reaches more than 1100 meters in both areas. The main drainages are controlled by structures in both areas. Stream gradients are fairly steep about 200 meters per kilometer on the average. Both study areas are logging dis- TR tricts for the most part but certain portions still have primary dense tropical growth.

SAMPLING AND ANALYTICAL METHODS

The rock, soil and stream sediment samples were collected along a Brunton-tape traverse at intervals ranging from 50 to 100 meters. Only fresh rocks .were taken whenever possible. The sam- ples were obtained along active stream channels. For every sam- pling point of stream sediments, two soi?, samples - one each from the opposite banks of the stream were collected. The stream sedi- ments consisted essentially of sand and very little clay or organ- ic matters. More than 175 rocks and a total of 2990 soil and stream sediment samples were collected-from an area of approximate- ly 500 sq. km. in Nabunturan, Davao del Norte. Around 100 rock samples and more than 700 soils and 3treara sediments were collec- ted from Malita, Davao del Sur covering an area of 200 sq, km.

Drying of the soil and stream sedimeo' aamples were done by placing the samples in aluminum pans and heating over a gaB bur» ner. The dried samples were then sieved vising an 80-mesh stain- less steel screen. The undersized samples were then kept for •nàlyèia The rock samples were crushed and pulverized prior to 1. background, analysis. . - - -2. coefficient

The determination of scandium, iron and cobalt in rocks a. geome were done by instrumental neutron activation analysis.' The ÏÏSGS b. boeff rock standards, J»CR-1, GSP-1 and AGT-^I which were obtained from c. coefi o ©

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3. threshold, t the US Geological Survey werj used as referance standards. The values of Sc, Co and Pe for these rocks were compiled by Flanagan, (1969). The determination of copper in rocks, soil and stream sediments was performed by colorimetric biquinoline method. These analytical methods were described by Santos and Palabrica, (1972).

TREATMENT OP DATA

Simple statistical techniques were used in the interpreta- tion of the geochemical prospecting data. Construction of cumu- lative frequency distribution for each analyzed element and corre- lation diagrams greatly helped in obtaining statistically and geologically significant data. Previous investigations, Ahrens, (1954)} Shaw and Bankier, (1954)} Tennant and White, (1959)i Barth, (1961)} Putman and Alfors, (1967); Williams, (1967)$ Le- peltier, (19^9) had graphically presented considerable amount of data as cumulative frequency curve and had suggested the tendency of some elements to be lognormally distributed in rocks and minerals.

Cumulative Frequency Distribution

Cumulative frequency curves for each element were made by plotting on a probability-log paper the concentration in parts per million (ppm) or percentage (fo) of the element against the percent cumulative frequency (,oCF). All the determined elements appe-red to have lognormnl distributions. Prom the cumulative frequency lines the following statis- tical parameters were calculated: 1. background, b 2. coefficient of deviation a. geometric deviation, s1 b. coefficient of deviation, s c. coefficient of variation, s"

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3* threshold, t A correlation bet The background b or mean value is a rough estimate of the ave- elements are lognormal rage concentration of the elements in a given environment, The back- between two elements c ground value, b could be determined graphically by taking the inter- of correlation (p). 1 section of the 50$ cumulative frequency. pendency» Lepeltier, 1 The geometric deviation, s is a factor obtained when value measure the degree of given by the intersection of the distribution line with 16$ ordinate are considered tenors is divided by the value of the background. The correlation c The coefficient of deviation, s is equal to the logarithm to to -1. P can be equal the base 1iO of the geometric deviation, a>. It is..» aoasure-of the complete independence scatter of the value around the background, indicating the disper- is a functional relati sion index specific for the distribution of a particular element in rect when P is-positiv a given surrounding. According to Lepeltier, (1969) the coefficient •if of deviation can also predict the degree of homogeneity of the dis- I A correlation clo tribution. He observed .that in rocks " a similarity in the coeffi- aation of the correlat cient of deviations with similar average values may indicate similar cloud (Figures 10 to 1 geochemical processes in their formation". jMti+hm to the two ordinateo 0 The relative deviation or the coefficient of dev&frt&wi, s" is ' of the two elements in expressed in percentage s" = s/b x 100. Lepeltier, (1969) conclu- senting the background ded that the relative deviation could bë an expression of the geo- graph into four quadra chemical law which states that the dispersion of an element is in- counted and added as f versely proportional to its abundance. He noted that when the back- L « number of ground is high, there is relatively a low coefficient of variation. number of The threshold, t could be read directly on the abscissa of the P can be calculated us intersection of the distribution line with the.2.% ordinate. The threshold could be calculated as» t = b x s' j or using logarithms, P » sin log t « log b + 2s* The threshold value is therefore dependent on both the background and the deviation. The threshold value is very If P is equal or : significant because it iB the limit above which the values are ano- to the coordinate axes malous. In geochemical prospecting, the aim is to locate these a- dent of each other* I nomalous values. In complex distributions, the threshold is ; eon* is inclined relative t veniently taken at the break above the normal-threshold"level of exists between; thé two lation coefficient cou o ©

related and if one finder for the otiie: A correlation between two or more elements may exist when these elements are lognormally distributed* The geochemical relationship RE: between two elements can be shown by a factor called the coefficient of correlation (P). The factor P is a measure of the degree of de- The extent of pendency. Lepeltier, (1969) used thi» coefficient of correlation to and rocks in del Su: measure the degree of dependency of two lognormal vari'ables which 2, respectively. T are considered tenors of two elements in a sanple population* copper, scandium, i in these maps. The correlation coefficient, P can have a value ranging from -1 In Malita, nea to -1. P can be equal to zero or approaches zero whea there is a were observed near complete independence between the two elements. When P » il, there medium-grained horn is a functional relationship between the two variables, either di- is located about 7 rect when P is-positive or inverse when P is negative. cent reef limestone A correlation cloud or diagram is used in the graphical esti- ments. The altered mation of the correlation coefficient. To construct a "correlation nic breccia with as cloud (Figures 10 to 17) the values of the two elements are assigned The breccias nre te: to the two ordinateo of a fully logarithmic paper and the contents consists of grey bai terial and is probn! of the two elements in each samples are plotted* The axes repre- known basement. Go senting the backgrounds of the two elements are drawn dividing the Two major foul- graph into four quadrants. The points located in each quadrant are south trending faul- counted and added as follows! west trending fault N. = number of points in the 1st and 3rd qu'drants Malita River. Moun N2 = number of points in the 2nd and 4th quadrants is essentially the , P can be calculated using the formula* There is no certain structure in bhe Ma the geology of the_ In Figure 1, f If P is equal or nearly zero, the cloud has its axis parallel in rocks were, locat to' the coordinate axes denoting that the two elements are indepen- Only a few copper s dent of each other. If P is clearly different from zero, the cloud of this creek is co is inclined relative to the coordinates and a relationship either soil geochemical se exists between the two elements. ^The correlation cloud and corre- lation coefficient could indicate when two elements axe spatially

O III) ! \ i i_ related and if cao clement may be used as an indicator or path finder for the other.

RESULTS AHB DISCUSSIO1Ï

The extent of the field sampling of soil, stream sediments and rocks in del Sur and del Korte are f.llustratod in Figures 1 and 2, respectively. ïhe corresponding sites where anomalous values of copper, scandium, iron and cobalt were obtained are al~o indicated in these maps» In Mali ta, near Mount Latian» chalcopyrite-pyrite stringers were observed near the fault contact between basaltic-andesitic and mediun-grained hornblende diorite. Locally, at Tecal creek which is located about 7 km. southwest of Malita town, the rocks are Re- cent reef limestone capping pillow lava, metavolcanics and metasedi- aents. The altered pillow lava underlies a highly silicified volca- nic breccia with associated massive coarse to medium-grained pyrite. The breccias are terminated by "pebble gouge" or tuff breooias. Th-V- consists of gvey br.saltic-andesitic pebbles to tuffaccous clayey ma» terio.1 and is prob&Tsly a unit separating the pillow lava and an un- known basement» Gossan occurs in the gouge area. Two major faults» are inferred in the Halita area - a north- south trending fault delineated by the Batanan River and the north- west trending fault whioh gave rise to the prosent position of the Molita River, Mount Latian which is located southwest of the area is essentially the geonorphological expression of a diorite stook. There is no "certainty, however, if the fault was prodiorite. ïne structure in th« Malita area is complex and little is known about the geology of the area. In Figure 1, five copper, four cobalt and one iron anomalies; in rocks were located in Sangay creek, a tributary of Batanan River. Only a few copper soil anomalies were observed. The drainage area of thi>* creak is considered promising enough to warrant copper grid soil geochemical sampling. ï^r^?^¥;7r^ O

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Teoal creek, a tributary of Malita River, revealed several iron ranging from 240-320 ppm, anc anomalies and one copper anomaly in the rocks. A few copper anoma- ging from 295-510 ppm were n< lies in soil were also detected. It is significant to note that the respective cumulative frequoi iron anomalies are mainly due to the presence of massive pyrite mi- values may be attributed to £ neralization and could possibly contain some local copper values* Soils from del Morte give a : Detailed geologic and copper grid geochemical surveys are highly re- value than the soils from de] commended for the Tecal area. .. B. Stream Sediments, In Nabunturan, mineralizations are associated with diorite dikes in stream sediments from del containing pyrite, chalcopyrite, galena and minor malchite. The of at least two populations, major Philippine fault or rift passes east of Nabunturan, hence the sediments shows a uni-modal structures in the project area are mainly characterized by north- values (Figure 4)» The backj south trending fault which are outlined by major rivers and creeks. are similar. However, the tl In Figure 2, a cluster of scandium, cobalt, iron and copper higher than the del Sur value anomalies were recognized in the upper Hanat creek, a tributary of- pies from del Sur as comparée tfanat River. The full significance of this occurrence is still un- I C. Rock Sampler The resolved. However, except for the good correlation between scandium Norte and del Sur are shown and cobalt, other element pairs show poor correlations in rocks. 5 illustrates more than one Conventional stream sediment and soil copper geochemical anomalies peltier, (lQ6

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ranging from 240-320 ppm, anc" nine copper values from del Sur ran- ging from 295-510 ppm were not included in the construction of their respective cumulative frequency curves. Some of these very high values may be attributed to samples taken from mineralized zones. Soils from del Borte give a lower background and a higher threshold valu.e than the soils from del Sur (Table l).

B. Stream Sediments. The cumulative frequency line of copper in stream sediments from del Horte (Figure 3) implies the presence of at least two populations. The distribution line for the del Sur sediments shows a uni-modal population with a slight excess of low values (Figure 4)« The background values for the two project areas are similar. However, the threshold value (227 ppm) in del Norte is higher than the del Sur value (156 ppa)• There were only 179 sam- ples from del Sur as compared to 944 samples from del Norte.

C. lock Sampler» The distributions of copper in rocks from del Norte and del Sur are shown in Figures 5 sad 6 respectively. Figure 5 illustrates more than one population. Following the method of Le- peltier, (1969)» the data was split at about the mid-point of the curve (^535» level)„ The splitting of the data wgs performed to show that the distribution curve r:ould be further resolved to indicate the presence of more than two populations in the sampled data. The two distinct populations, A and B both have a uni-modal distribution. The copper data in del Sur rocks have an abundance of low values as shown by the negative break at 25$ level.

The rocks from del Norte were analyzed for copper using the bi- quinoline method. The rocks from del Sur were analyzed using atomic absorption spectrometry. The former method extracts 30-6095 of the total copper, giving the geochemical copper data. The latter method measures the total copper content„ It may be noted that either of these two methods could be used in copper content determination.

Scandium Distribution The cumulative frequency line for scandium in del Horte rocks

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-10- essentially lognormal c (Figure 7) indicates a multi-modal population. Fourteen values for del Horte rocks (Fd ranging from 64*185 ppm wore not included in the construction of The distribution of col the frequency distribution curve* The background and threshold a negative break at 84? values are 1? ppm and 38 ppm respectively. Splitting of the Sc tributed to an excess data from del Horte shows two distinct populations as given in sidered. The statisti< Figure 7* Population  is made up of more than one population. the two project diBtrii Population B is uni-modal. The distribution of Sc in del Sur threshold values (Tabl< rocks likewise implies more than one population (Figure 8). The data was split to identify populations A and B shown in Figure 8. The present study for basalts, Prinz, (li The background values of Sc in del Norte and del Sur do not poor in olivine and py: differ much, unlike their relative deviation which is 0.82$ in del Norte and 2.64$ in del Sur. This relatively high coefficient of centrated in theee min

variation or relative deviation in del Sur rocks nay be due to •1 sample heterogeneity. Iron Distribution The Sc background of basaltic-andesitio rocks in the project There are at leas areas is lesB than those given by Fryklund and Fleischer, (1963)1 frequency distribution Norman and Haskin, (1968)1 and Shimizu and Euroda, (1969) for si- existence of an esseni milar rock types. However, the present Sc background is close to Sur rocks is confirmed the computer-derived value of 15.1 ppm for igneous rocks, Horn and approximately 15$ levé, Adams, (1966), It maybe added that Shimizu and Kuroda, (I969) values in the populate suggested 18 ppm Sc (geometric mean) for intermediate rocks of Ja- (ll ppm) considered at pan, which include andésites and diorites. The dominant mafic .the usual 2.5$ limit, minerals of andésites are hornblendes and lesser amounts of biotite anomalous sites in the in pyroxenes, amphiboles and to a lesser degree in biotites. The values of Fe are also present Btudy shows that the rocks in the study areas are more an- The Fe background desitic than basaltic. This observation agrees well with the gene- concentration is repre rally recognized occurrence of an "andésite line" which characterize below the Fe content c the volcanic rocks of the circum-Pacific belt which includes the Philippines. Correlation Coéfficier

Cobalt Distribution The correlation t del Norte; and del Sur Cobalt data in the rocks from del Horte and del Sur fit an So/Fe and Cu/Sc. for d<

'-(• MM I i i i n ill i M l n i l l TIB -11- essentially lognormal distribution. The cumulative frequency line for del Norte rocks (Figure 7) fias a slight break at the 50$ level..

The distribution of cobalt in del Sur rocks (Figure 8) also gives a negative break at 84$ level. These negative break could be at- tributed to an excess of low values in the populations being con- sidered. The statistical parameters of cobalt in the rockB from the two project districts are nearly similar, except for .their threshold values (Table 2). . The present study is much less thgn the median of 58 ppm Co for basalts, Prinz, (1969). The rocks of Davao are essentially poor in olivine and pyroxenes % and according to Prinz, Co is con- centrated in these minerals.

Iron Distribution There are at least two populations depicted in the cumulative frequency distribution 01' Fe in del Norte rocks (Figure 9)* The existence of an essentially uni-modal distribution of Fe in del Sur rockB iB confirmed in Figure 6. À Blight positive break at approximately 15$ level denotes that there is an excess of high values in the population. For this reason, the threshold value (11 ppm) considered at the abscissa of the break, which is above . the usual 2.5$ limit, was the reference value used in locating the anomalous sites in the project area. The background and threshold values of Fe are also elucidated in Table 2. '$ The Fe background is well within the range of this element concentration is representative andésites, Clark, (1924) and much below the Fe content of 8.2$ in basalts, Ahrens, (1963). i Correlation Coefficients of the Elements i The correlation coefficient of.the elements in the rocks from del Norte and del Sur are shown in Table 3. The coefficient values Sc/Fe and Cu/Sc for del Sur were not indibated but it can be stated ©

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The reconnaissar with confidence that the said values are rather low, in the order copper has revealed of 0.1-0.3. tical treatment; The correlation coefficient of Co/Cu in the two project areas (1) The distribi (see Table 3) denote an independency in the mineralization of these Dayao project area ge two elements» The negative correlation coefficient of these ele- tions. Copper in son ments in del Norte rocks indicate a tendency for an inverse rela- distributed. The di£ tionship, Figure 10 shows the correlation diagram of Go/Cu for del sediments are fairly Norte area- Nabunturan. There is a moderate correlation between cobalt and scandium (2) There is moc in both study areas» The correlation clouds, illustrated in Figures of scandium and coba] 11 and 12 are indicative that cobalt may be used as a pathfinder for were obtained for Sc/ scandium, and vice versa. The following ge A. In Nabunturs The correlation coefficient (p = O.4135) of Cu/Pe and its cor- a) A cluste relation diagram (Figure 13) suggest a slight-fair dependency in the lies in mineralization of these two elements in del Norte. In del Sur, b) Copper 4 however, the correlation coefficient of Fe/Cu is zero, denoting a sionall complete independence between the mineralizations of these two ele- dongan c ments. This is in contrast with the findings of Jerome, (1966) who B. In Malita, D noted the "ubiquitous" presence of cobalt and iron (mainly as mag- a) Cobalt, netite) in his studies of poiphyry copper deposits in the provinces fined to of Arizona and New Mexico. The Fe/Cu correlation cloud for del Sur b) Iron ano rocks is given in Figure 14. Tecal cr Poor to slight dependency between Co/Fe, Fe/Sc and Sc/Cu are high iro indicated by the low correlation coefficients for both project pyrite n areas. The correlation diagrams of the above element pairs for del gical, g 3. Norte are shown in Figures 15, 16 and 17. performe extent c nomic cc c) Isolated

o Ï8. I I 1 1 IMOl TTT 18 t o

CONCLUSIONS

The reconnaissance surveys for scandium, cobalt, iron and copper has revealed the following observations using data statis- tical treatments (1) The distributions of Se, Co, Fe and Cu in rocks from the Davao project area generally follow logarithmic normal distribu- (5) tions. Copper in soils and stream sediments is also lognormally distributed. The distributions of copper in soils and stream sediments are fairly similar in Malita and distinctly different in Nabunturan. (2) There is moderate correlation between the mineralizations of scandium and cobalt for the project areas. Poor correlation were obtained for Sc/Cu, Sc/Pe, Co/Cu and Cu/Pe in both areaB,

The following geochemical anomalies were located: Ac In Habunturan, Davao del Norte: a) A cluster of scandium, cobalt, iron and copper anoma- lies in the upper Manat creek, b) Copper anomalies mostly in stream sediments and occa- sionally in soils and rocks from Saraban and Matag- dongan creeks. Bo In Malita, Davao del Sur: a) Cobalt, scandium and copper anomalies essentially con- fined to the Sangay creek. b) Iron anomalies with one copper anomaly situated in Tecal creek. Field observations indicate that the . high iron values are due to the occurrence of massive pyrite mineralizations in the area. Detailed geolo- gical, geochemical and geophysical surveys could be performed in the Tecal creek area to delineate the extent of this pyrite deposit which may contain eco- nomic copper values. c) Isolated and insignificant copper anomalies in soils

"''T'"- ' Q % 8 O -MM—1—1 n m i i 1 t 1 i 1 tl~f O o o

-14- Table 1 Statistical Sediment Sa and stream sediments occurring in the other traverse Table 2 Statistical Cobalt in H creeks. Table 5 Correlation (5) The present technique could be conducted in areas of Norte and B low to moderately high relief with grassy to tropical rain forest vegetation. It is interesting to note that the degree of correlations for Sc/Co in the Davao areas are similar to those of northern Bohol, Santos and Palabriea, (1972). However, poor correlation between Figure Location li copper and scandium or cobalt and iron were noted for both regions Anomalous which are for the most part underlain by basaltic-andesitic rocks. Figure Location Anomalous Figure Cumulative and S treat Figure Cumulative Stream Se< Figure Cumulative from Davac ACKNOWLEDGEMENTS Figure Cumulative Rocks fron Figure Cumulative We would like to express our thanks to Mira Mining Corpora- Cobalt in tion for their help in the collection of samples; to the Philip- Figure Cumulativ< pine Bureau of Mines for the use of their crusher; to the Staff Cobalt in of the Reactor Operations Department of PARC for irradiating our Figure 9 Cumulativi from Dava< samples; to P, Kapauan and E. Zuleta for their assistance in the Figure 10 Correlatii atomic absorption work. del Norte Figure 11 Correlati Davao del Figure 12 Correlati Davao del

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List of Tables

Table 1 Statistical Parameters for Copper in Soil and Stream Sediment Samples from Davao del Sur and Davao del Norte Figure 13 Correlation del Norte Table 2 Statistical Parameters for Copper, Scandium, Iron and Cobalt in Hocks from Davao del Sor and Davao del Norte Figure 14 Correlation del Sur Table 3 Correlation Coefficients of the Elements in Davao del Norte and Davao del Sur Rocks Figure 15 Correlation del Norte Figure 16 Correlation del Norte Figure 17 Correlation List of Figures Davao del N

Figure 1 Location Map of Davao del Sur Project Area Showing Anomalous Points Figure 2 location Map of Davao del Norte Project Area Showing Anomalous Points Figure 3 Cumulative Frequency Distributions of Copper in Soils, and Stream SedimentB from Davao del Norte Figure 4 Cumulative Frequency Distributions of Copper in Soils, Stream Sediments from Davao del Sur Figure 5 Cumulative Frequency Distributions of Copper in Rocks from Davao del Norte Figure 6 Cumulative Frequency Distributions of Iron and Copper Rocks from Davao del Sur Figure 7 Cumulative Frequency Distributions of Scandium and Cobalt in Rocks from Davao del Norte Figure 8 Cumulative Frequency Distributions of Scandium and Cobalt in Rocks from Davao del Sur Figure 9 Cumulative Frequency Distributions of Iron in Rocks from Davao del Norte Figure 10 Correlation Diagram Cobalt/Copper of Rocks from Davao del Norte Figure 11 Correlation Diagram Cobalt/Scandium of Rocks from Davao del Norte Figure 12 Correlation Diagram Cobalt/Scandium of Rocks from Davao del Sur

( S ! ! I * I I I n 1 ir-, ill i i i i i Figure 13 Correlation Diagram Iron/Copper of Rocks from Davao del Norte Figure 14 Correlation Diagram Iron/Copper of Rocks from Davao del Sur Figure 15 Correlation Diagram Cobalt/iron of Rocks from Davao del Norte Figure 16 Correlation Diagram Iron/Scandium of Rocks from Davao del Norte Figure 17 Correlation Diagram Scandium/Copper of Rocks fron Davao del Norte

Î

*? Table 1, Statistical Parameters for Copper in Soil and Stream Sediment Samples from Davao del Sur and Davao del Norte

Soil Samples Stream Sediments STATISTICAL PARAMETERS del Norte del Sur del Norte del Sur

Background, b (ppm) 6? 79 68 72

Geometric Deviation, s1 (ppm) 1.9^ 1.52 1.83

Coefficient of Deviation, s (ppm) 0.288 0.18 0.262 0.17

Relative Deviation, s" (#) 0.1*3 0.22 0.39 0.23

Threshold, t (ppm) 252 (350) 183 (175) 227 (226) 156 (135)

Note: ( ) threshold value obtained from the graph

Table 2. Statistical Parameters for Copper, Scandium» Iron and Cobalt in Bocks from Davao del Sur and Davao del Norte

STATISTICAL PARAMETERS E L IT" B N. T S ; : Copper .Scandium i Iron I Cobalt STATISTICAL PARAMETERS t 1 t '. w,

Table 2, Statistical Parameters for Copper, Sctsndiuait Iron and Cobalt in Rocks from Davao del Stir and Davao del Norte

E L E . M E h STATISTICAL PARAMETERS r. T s • ,• Copper . .Scandium Iron Oobalt STATISTICAL PARAMETERS geochem Cu total Cu del Norte del Sur del Itorte del Sur del Norte del Sur del Norto del Stir 1 i, Background, b (ppm) 33 125 17 12 15

Geometric Deviation» sf 2.£> 1,68 1.5 2 r- l o-42 1.83 1162 1.86

Coefficient of Deviation, s 0.435 0,225 0 180 0.370 .152 0.263 0.210 0.270

Relative Deviation, E" ($>) 1.32 0.18 0 82 2 3.8 4.38 1.74 1.80

Threshold, t (ppn) 244 (180) 553 (285) 38.0(34) 77 (45) 8 (9) 20 (27) 31(31) 52 (52) •o nul Note: ( ) threshold value obtained from the graph and applied in the present work C 3 threshold value obtained above the 2.,% level

': - %'-i\

Table 3* Correlation Coefficients of the Elements in Davao del Norte and Dàvao del Sur Hecks O Tabl» 5« ' Oorrolation Coefficients of the Elements in Bavao del ïrort* «ad Davao del Sur Rocks

", it »! C (>R'BS L A !P2;0 1f COEFP ICISHÏS

: , EHeaenta , Bavao del Norte Davao del SUB

Oo/Cu -O.OQ97 ,0.1564 ; bo/so Û.6662 \ : ^ ' 0'.6374 ; _ ;: .•'; - • , 1

.. ' «, ;. • •;••... • ïVcu > ^ ; 0.4135 r B, 0.2933 0.2181 ;-l O.317I ' .• " ; "•-" '.,. sc/cu- .-•• - .••,(] 0.1220 I4Ï'*?I' Si -~7"ir -.-arnKEsSS asJHB^Ks-affSfw.pr-rsaï'-iiiiîH'TOR'^ï.iîri'tâ-J.ïr-.'^ilM'îï-''." ô REFERENCES

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-:•;---"* '

~rSC---—^ - ' -'-•• " "--"^:— '$--"' (

1 6 ;f il»

t Santos, G.G. and Palabrica, O.T., 1972, Geochemical activation I ( analysis survey in northern Bohol for Scandium, Cobalt and and Iron: In press. Shaw, D.M. and Bankier, J.D., 1954, Statistical methods applied to geochemistry! Geochim. Cosmochim. Acta., v. 23, pp. 116-134.

Shimizu, T. and Kuroda, R., 1969, Abundance of Scandium in ] igneous rocks of Japan: Geochim. Cosmoehim. Acta, v. 33, pp. 290-292. Tennant, C.B. and White, M.L., 1959» Study of the distribution data: Econ. Geol, v, 54j PP. 1281-90. Williams, X.K., 1967, Statisticr in the interpretation of geo- chemical data: N.Z. Jour. Geol. Geophys, v. 10, PP. 771-797.

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