PART III Conclusions and Recommendations Chapter１ Conclusion

(1) Satellite Image Interpretation

As a result of rationing of satellite image interpretation of this year, a sizable anomaly of R21 (iron oxide index) is distributed in the quadrangle of 32-q, 32-r and 31-r in the east of the survey area. The anomaly is tend to be larger in the geological units of PN-ta (Holocene pyroclastics) and tend to be smaller in Ks-ti (upper Cretaceous intrusives), JK-yu (Jurassic to Cretaceous sediments), Ks-se (upper Cretaceous sediments) and Ks-ar (upper Cretaceous sediments). A sizable anomaly of R57 (clay mineral index) is distributed in the quadrangle of 32-q and 32-r in the east of the survey area, although the anomalies are distributed all over the survey area. They tend to be concentrated in the geological units of PeB (pre Cambrian metamorphics), JK- yu (Jurassic to Cretaceous sediments), Ks-ti (upper Cretaceous intrusives), PN-ta (Neogene volcanics), NQ-ba (Quaternary volcanics) and Q-and (Holocene pyroclastics). Conspicuous anomalies are located in alluvium and along the existing river. In the east of the area, conspicuous anomalies are located in the units of JK-yu, PN-ta, QN-ba and Q-and. The lineaments of Andes trend (NW-SE) are predominantly distributed in the survey area. However, the lineament of E-W is predominantly distributed in the quadrangles 32-o and 32-p. This is probably due to the effect of Abancay Deflection which deflect the trend of strata to E- W from Andes trend (NW-SE) located to the north of the survey area. Pattern of lineament density is generally conformable to the above-mentioned Andean trend and the deflection. High lineament density area is coinciding with the area of the deflection. In comparison with geologic units, the lineament density tend to be lower in the young geological unit e.g. Tertiary system and Quaternary system, while lineament density tend to be higher in the old geologic units, consisting of Paleozoic and Mesozoic formations. Relationship between the result of image interpretation and known mineral showings are summarized as follows: 1. Although the vein type ore deposit predominates over the survey area, a correlation between lineament density and distribution of ore deposits is not clear. 2. Between the location of vein type deposits and indices of iron oxide and clay mineral, the following relationship is recognized in general. 1) In case of ore deposit is located in Cenozoic formation, the ore deposit is accompanied by either iron oxide index or clay mineral index in any case. 2) In case ore deposit is located in Mesozoic or Paleozoic formation, the ore deposit is accompanied by either index as the case may be. 3. Location of manto type ore deposit coincides with the area of high lineament density. 4. Neither iron oxide index nor clay mineral index appear in the area of manto type ore deposit. 5. Ore deposit of disseminated type and stockwork type is located around the area of relatively high lineament density. 6. Ore deposit of disseminated type and stockwork type is commonly accompanied by either iron oxide index or clay mineral index even though they are weak. Particularly this is clear in the case of ore deposit occurs in Cenozoic formation.

(2) Existing Data Analysis

Metamorphic rocks, sedimentary rocks and volcanic rocks of pre Cambrian to Quaternary age, elongating northeast to southwest, are widely distributed in the survey area. Penetrating them, intrusive rocks of Ordovician to Silurian, Cretaceous to Paleogene and Neogene in age are located. In the southwest and east of the survey area pre-Cambrian metamorphics are

- 119 - distributed, and the younger sediments and volcanics are orderly distributed to the north. The area is divided into the metallogenic zones of Paracas-Chala, Mala-Nazca, Nazca-Ocoña and Puquio-Caylloma from the Pacific Ocean side to inland. In comparison with the previous Peruvian metallogenic provinces, Paracas-Chala metallogenic zone corresponds to the cupreous sub-province, the iron ore zone. Mala-Nazca metallogenic zone corresponds to the cupreous sub-province, the copper ore zone, Nazca-Ocoña metallogenic zone corresponds to the cupreous sub-province, the gold ore zone and Puquio-Caylloma metallogenic zone corresponds to the polymetallic sub-province respectively. Number of ore deposits and mineral showings of this area totaled 260. Among them 238 is vein type deposit, of which 172 is gold vein or gold copper vein, that shows the character of Nazca- Ocoña metallogenic zone. 56 vein type copper deposits show the character of Mala-Nazca metallogenic zone. Manto type deposits totaled 15, of which 12 are manto type iron deposits and two are manto type iron copper deposits. Ore deposits of the Marcona mine, the only producer of iron ore in Peru, are composed of the above two types of manto type deposits. Around the Marcona mine six iron ore veins and three iron copper ore veins are known to occur which show the character of Paracas-Chala metallogenic zone. Aside from them the existence of four dissemination type deposits and three stockwork type deposits is known. Considering mineral paragenesis of those showings, it is very meaningful that a few mineral showings with only gold occur in volcanic rock of Cenozoic age. That suggest the existence of gold mineralization related to young volcanism can be expected. Since the host rock of these showings are the Tacaza group and the Camaná group of lower Miocene age, the Barroso group of Pleistocene age, the gold mineralization seems to have taken place continuously from Miocene to Holocene. The existence of stratabound type ore deposit in the area of gold vein in Mesozoic sedimentary rocks is a subject worth studying as there is a description of a small manto type copper gold showing in the Seraj formation of Mesozoic age. Metallogenetic study on those ore deposits and mineral showings except for the Marcona mine has not been conducted. From the existing data and distribution of mineral showings, mineralization in the survey area is classified into the following types. · Manto type and vein type iron (copper) deposits related to andesitic intrusives of late Mesozoic age. · Gold vein, gold-copper vein and copper vein related to the Coastal Batholith of late Cretaceous to Paleogene age. · Vein type, dissemination type and stockwork type gold deposit related to volcanic rocks of Miocene to Holocene age. Among the above types of mineralization, the target of this survey is to be placed primarily on the gold deposit related to volcanics of Miocene to Holocene age and secondarily the gold vein related to the Coastal Batholith.

(3) Overall Analysis

Based on the results of the satellite image analysis and existing data analysis, 1) Iron oxide index anomaly obtained by satellite image analysis 2) Clay mineral index anomaly obtained by satellite image analysis 3) Density of lineament 4) Distribution of volcanic rocks of Miocene to Pleistocene 5) Distribution of the Guaneros formation, the Yura group and the Casma group of Mesozoic age 6) Location of known mineral showings

From the above basis the following five area s are selected as a promising area.

- 120 - ① Nazca area ② Tocota area ③ Chuquibamba area ④ Andagua area ⑤ Orcopampa area

Basis of the judgment is indicated in the following table.

Table of Promising Area

Area Center R21 R57 Lineament Objective Known Coordinates (Iron (Clay Mineral Density Country Rocks Indication Oxide Index) Index) ①Nazca 14ﾟ25’S Weak near Small scaled in High density JK-yu Au Vein type 75ﾟ15’W Yura Group Yura G., trends Summit (Yura Group) NW-SE

②Tocota 15ﾟ40’S Small scaled Medium scaled High density Js-gu Au Vein type 74ﾟ10’W within Guanero along fault 3 summits (Guaneros F.) s Formation system in Guan JK-yu eros F. (Yura Group)

③Chuqui- 15ﾟ40’S Large scaled Small scaled Saddle PN-ta Au bamba 72ﾟ45’W within Tacaza G in Tacaza G. Between high (Tacaza G.) Dissemination roup and and Barroso G. density summi NQ-ba type continue to Barr Overlap to R21 ts （Barroso G.） oso Group in part

④Andagua 15ﾟ30’S Large scaled Small scaled High density PN-ta nothing 72ﾟ25’W within Tacaza G in Tacaza G. 2 summits (Tacaza G.) roup and and Barroso G. NQ-ba continue to Barr Overlap to R21 （Barroso G.） oso Group in part

⑤Orcopampa 15ﾟ20’S Large scaled Medium scaled High density PN-ta Au Vein type 72ﾟ15’W within Tacaza G in Tacaza G. 4 summits (Tacaza G.) Dissemination roup and and Barroso G. NQ-ba type continue to Barr Overlap to R21 （Barroso G.） Stockwork oso Group in part type

- 121 - Chapter ２ Recommendation in Future

As this year’s survey and analysis revealed that the survey area is promising in potential for mineral resources, a field survey to confirm the potential is to be conducted in future. In conducting the ground survey it is important not only to make a correct interpretation on each geological fact, but also to consider the position of each geological fact in the whole geological setting of the area. Understanding of the regional geological character is also important. The main objects of survey in the selected district are described as follows;

① Nazca area The district is widely underlain by the Yura group of Mesozoic age. Intrusive rock of the Tibaya Super unit is extensively distributed in the north and south of the district. Occurrence of a number of vein type gold deposits is known.

Therefore, in order to obtain the data of gangue mineral composition, formation temperature of ore deposits, wall rock alteration, a field survey is to be conducted. Then the possibility of existence of concealed stratabound deposit is to be studied.

② Tocota area The area is widely underlain by the Guaneros formation. The Tibaya Super unit and the Bella Union complex are distributed in the north of the area, where vein type gold deposits are concentrated. A small anomaly of clay mineral index is located near the contact of the Tibaya Super unit in the east of the area. A part of the above anomaly is overlapped by the anomaly of iron oxide index.

③ Chuquibamba area The area is distributed by extensively the Miocene Tacaza group and the Pleistocene Barroso group. The district is located on the north of high density area of lineament. A number of iron oxide index anomalies are concentrated and a part of them are overlapped with a scattered clay mineral index anomaly. Existence of an indication of disseminated type gold deposit is known.

Therefore, to verify wall rock alteration zone that was extracted from the image and to collect geological data including rock specimen, a field survey is to be conducted. An overall analysis of the data of alteration mineral composition, formation temperature of alteration minerals, assay result of rock specimen etc. is to be conducted to find the possibility of existence of epithermal gold deposit is to be studied.

④ Andagua area The area is overlain by the Miocene Tacaza group and the Pleistocene Barroso group. The elevated lineament density zone including high lineament density peaks with trend of NW-SE is located in the area. Small anomalies of iron oxide index are concentrated and a part of them are overlapped with a scattered anomaly of clay mineral index. There is none of known mineral showing. To verify wall rock alteration zone that was extracted from the image and to collect geological data including rock specimen, a field survey is to be conducted. An overall analysis of the data

- 123 - of alteration mineral composition, formation temperature of alteration mineral, assay result of rock specimen etc. is to be conducted to find the possibility of existence of epithermal gold deposit is to be studied.

⑤ Orcopampa area The area is overlain by mainly the Miocene Tacaza group , the Pleistocene Barroso group and the Holocene pyroclastics. And the area locates in the elevated zone of the lineament high density including high lineament density peaks. Concentration of anomalies of iron oxide index is recognized. And a part of them are overlapped with the anomaly of clay mineral index. There is an operating mine in the area. Therefore, to verify the wall rock alteration zone, which was extracted from the image and to collect geological data including rock specimen. A field survey is to be conducted. An overall analysis of the data of alteration mineral composition, formation temperature of alteration mineral, assay result of rock specimen etc. is to be conducted to find the possibility of existence of epithermal gold deposit.

It is recommended to conduct a field survey in consideration of the above-mentioned matter.

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Confirmation Survey of the First Year Extracted Areas

In consideration of iron oxide index, lineament density which are obtained by satellite image analysis, and the age and rock facies of intrusives, character of the known mineral showings which are obtained from the existing data analysis, five districts namely Calhuahuacho, Livitaca, Macusani, Usicayas and Vilque were selected for a field survey to confirm the above geological factors. The INGEMMET has conducted a field survey for 30 days in the above five districts, and prepared a report "Informe de la verificación de campo de las anomalías Espectrales - Franja 2". The field survey, using rock geochemical survey at the same time, was conducted in the area of anomaly where mineral claim was not applied. 35 elements of which 34 are assayed by ICP, in addition to Au by fire assay. The assay result is shown in Table 1. The area of selected districts and the surveyed districts is shown in Fig.1. Result of the field survey is as follows:

1. Calhuahuacho district (Fig.2, Fig.3)

The skarn type and hydrothermal strata-bound copper (and iron) deposits such as Ferrobamba, Chalcobamba, Sulfobamaba, Charcas are located in the north of the district. Result of image analysis showed that the area has a high potential for hydrothermal deposit as the lineament density is high suitable for circulation of hydrothermal solution and the anomaly of the iron oxide index is located around the intrusives. The field survey has been conducted in three areas, and 12 samples were collected. As the result of assay and field survey, it was concluded that the area is no longer interested. However, although the geological setting of the area is not clear, assay result of two samples shows high As and Pb (100 times of the Clark Number) and Au is in the order of 100 ppb. Therefore, the character and occurrence of the samples are to be studied prior to the final conclusion. Table 2 shows comparison of the selected area and the area of field survey carried out by INGEMMET. The area of field survey covers only 15% of the selected area. Therefore, it is too hasty to evaluate the whole area by the result of survey. On the southeast of the survey area 3, an anomaly of the iron oxide index in the Tertiary intrusives has been detected, a field survey including this area is necessary.

2. Livitaca district (Fig.4)

The district was thought to has a high potential for existence of skarn type and/or vein type deposits, as there are skarn type Fe deposit (Livitaca), Cu-Pb-Zn deposit (Lomas de Oro), high

- 2-1 - lineament density and concentration of anomalies of iron oxide index around Tertiary intrusives. The field survey has been conducted in two area, the one is located within the selected district and the other is located in outside of the selected district on the west adjacent to the above area . Four samples were collected and assayed in the area within the selected district. As a result the conclusion was negative. In the area outside of the district 14 samples were collected and assayed. As a result anomaly of rock geochemistry, of which Au, Ag, As, Ba, Pb, Zn assay are 100 times of the Clarke number, was detected. It is concluded that the ANAD procedure (to prohibit application of mineral claim is to be taken and then a detailed field survey is to be conducted. As the area of field survey covers only 10% of the selected area, it is difficult to evaluate the whole area. Occurrence of an iron oxide index anomaly in Tertiary intrusives has been known in the survey area 4, and geochemical anomaly was found in the same area. The combination of acidic intrusive rock and iron oxide anomaly is seems to be important in selecting a promising area.

3. Macusani district (Fig.5, Fig.6)

Occurrence of vein type deposit (San Rafael, Quenamari, etc.) and manto type deposit (Cerro del Inca Nro. 28) in and around Tertiary intrusives is known. As the iron oxide index anomaly tend to be concentrated around the intrusives and lineament density is also high, it was indicated that the iron oxide index anomaly is probably indicating the existence of mineralized alteration zone. The field survey has been conducted in three areas and 11 samples were collected and assayed. As a result it was concluded that none of the area need further investigation. However, although the geological setting of the area is not clear, assay result shows three samples from two area are high in As and Pb corresponding to 100 times of the Clarke number, therefore the character and occurrence of the samples are to be studied prior to the final conclusion. As the area of field survey covers only 6.36% the Macusani district, it is difficult to evaluate the district from the survey result. Especially in and around Tertiary intrusives where the San Rafael deposit occur, is not included in the survey area probably due to the mineral claim. The most important area has not been surveyed yet.

4. Usicayos district (Fig.7, Fig.8)

The district is located to the northeast of the Macusani district. A number of mineral showings

- 2-2 - including polymetallic dissemination type deposit (Sarita) occur in the area. The area was selected to a promising district as the lineament density is somewhat higher and there is a concentration of iron oxide index anomalies in Carboniferous to Permian sediments. The field survey has been conducted in four areas and 15 samples were collected and assayed. As the result, it was concluded that none of the area needs further investigation. However, although the geological setting of the area is not clear, assay result of two samples showed high in As and Cu corresponding to 100 times of the Clarke number. Therefore the character and occurrence of the samples are to be studied prior to final conclusion. Although it is difficult to evaluate the district from the survey result as the survey area covers only 23.6% of the Usicayos district, the iron oxide index anomaly in this district may not always indicate the presence of mineralization, since no geochemical anomaly was detected in the survey area, where iron oxide index anomalies were concentrated.

5. Vilque district (Fig.9, Fig.10)

The area was selected as a promising district due to that the occurrence of known mineral showings are concentrated around Tertiary intrusives where iron oxide index anomalies are also concentrated, and lineament density is slightly higher. The field survey has been conducted in two areas and nine samples were collected and assayed. It was concluded that no further investigation is required in both areas. Assay result of one sample shows high in As and Bi correspond to 100 times of the Clarke number and assay result of 17 ppb of Au was also obtained. Since there is a description of the presence of a small vein and small mine site in the area where the above samples were collected, a relationship to the above sample is to be studied. Although it is difficult to evaluate this district from the survey result as the survey area covers only 10.59% of the Vilque district, the iron oxide index anomaly in this district may not always indicate the presence of mineralization, since none of geochemical anomaly was detected in the survey area 14 where iron oxide index anomalies were concentrated.

6. Consideration

Based on the result of last years survey and analysis, the field survey including rock geochemical survey has been conducted in 16 areas in five district and total of 65 rock samples were collected assayed. As the result, it was concluded that further detailed survey is not worth to be conducted in 15 areas among them. In regard to the rock geochemical survey the assay result of a few samples shows an order of

- 2-3 - 100 times of the Clarke number. The meaning of such high assay value is to be clarified namely an overall analysis on the assay value of each rock type, rock alteration, mode of occurrence of the sample and mineralized alteration of surrounding area, etc. is to be conducted. As shown in the Table 2, the area of survey covers only 11.69% of the total promising area, it is difficult to evaluate every district from the survey result. Especially in the southeast of survey area 3 in the Calhuahuacho district and in the Macusani district a reconnaissance field survey is to be conducted in and around Tertiary intrusives where iron oxide index anomalies have been detected.

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