Doğu karadeniz metalojenik provensinde Balcılı (Artvin) ve Güzelyayla (Trabzon) bakır-molibden oluşumlarının jenetik etüdü
A Genetical investigation of Balcılı (Artvin) and Güzelyayla (Trabzon) copper-molybdenum occurrences in the metallogenic province of eastern pontid
Yazar: FUAT YAVUZ
Danışman: PROF. DR. YILMAZ BÜRKÜT
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü
Derece: Doktora, 1992
Konu: Jeoloji Mühendisliği = Geological Engineering
Dizin: Artvin-Balcılı = Artvin-Balcılı ; Bakır = Copper ; Molibden = Molybdenum ; Trabzon-Güzelyayla = Trabzon-Güzelyayla

Özet:
ÖZET Kuzey Türkiye'de yer alan iki bakır-molibden sahası, Balcılı(Artvin) ve Güzelyayla(Trabzon) bu çalışma kapsamında ele alınmıştır. Balcılı porfiri bakır mineralizasyonu tonalit ve granodiorit bileşimli pültonik kayaçlara, Güzelyayla porfiri bakır mineralizasyonu ise porfiritik dokulu andezit ve dasitlere bağlı olarak gelişmiştir. Kalk-alkali granitik bir magmanın ürünü olan inceleme alanı kayaçları, yoğun bir şekilde hidrotermal alterasyona maruz kalmışlardır. Balcılı granitoidleri daha ziyade peralüminyumlu ve göreceli olarak tasodik karakterlidir. Asıl cevherleş meyi bünyesinde bulunduran potasik kuşağın, Güzelyayla sahasına aranla daha geniş bir alanda yayılım göstermesi nedeni ile, I-tipi bir granitoidten S-tipi bir granitoi- de geçiş eğilimi gösterirler. Tektonik distriminasyon diağramlarında volkanik yay granitoidleri alanında dağılım gösteren Balcılı granitoidleri, ağırlıklı normal yay karakterinden doygun yay karakterine geçiş gösterirler. Magnezyo-hornblend bileşimli kalsik amfibolleri kapsamın da bulunduran inceleme alanı kayaçları; ortalama olarak 3.02±0.5 kbar kristalizasyon basınçlarında ve 791±75°C sıcaklıklarda duraylı hale gelmişlerdir. Bakır ve molibden disseminasyon ve damarcık şeklinde olmak üzere başlıca iki türde cevherleşme sergilerler. Jeokimyasal çoklu veri analizi değerlendirmeleri ile bakır 'in Kuzey- doğu-Güneybatı doğrultusunda ve Güneydoğu ' ya artan oran da konsantrasyon gösterdiği belirlenmiştir. Metaalüminyumlu ve daha ziyade peralüminyumlu Güzel yayla valkanoplütonik kayaçları, sodik karakterli olup, I-tipi granitoidlerin genel çizgilerini daha baskın bir şekilde kapsamlarında bulundururlar. Volkanik yay granitoidleri alanında yayılım gösteren volkanoplütonik kayaçlar, primitif ve normal bir yay doygunluğunun genel karakterlerini taşırlar. Magnezyo-hornblend bileşimli kalsik amfibolleri bünyelerinde bulunduran kayaçlar, ortalama olarak 2.71±0.5 kbar kristalizasyon basınçlarında ve 6B2-75 C sıcaklıklarda duraylı hale gelmişlerdir. Bakır disseminasyon, damarcık ve mikrodamarcıklar şeklin de, molibden ise disseminasyon ve damarcıklar şekilde izlenir. Jeokimyasal çoklu veri analizi değerlendirme yöntemleri.ile bakır ' m Kuzeydoğu-Güneybatı doğrultusun da ve Güneydoğu 'ya artan oranda konsantrasyon gösterdiği saptanmıştır. Lineer diskriminant analizi, % 90 güvenlik sınırı içinde, Balcılı sahasının Cu-Mo popülasyonunun % 75 Güzel yayla sahasının Cu-Mo popülasyonunun ise % B3 oranında merkezi indekse göre ayrılabileceğini göstermiştir. Buna göre, Güzelyayla sahası gerek cevher minerallerinin türü gerekse Cu-Mo popülasyonlarının dağılım sınırları açısın dan Balcılı sahasına göre önemli bir mineralizasyon alanı olarak ön plana çıkmıştır.A GENETICAL INVESTIGATION OF BALCILK ARTVİN) AND GÜZELYAYLA( TRABZON) COPPER-MOLYBDENUM OCCURRENCES IN THE METALLOGENIC PROVINCE OF EASTERN PONTID SUMMARY In the folloujing dissertation, turn porphyry copper mineralization areas Balcılı (Artvin ) and Güzelyayla (Trabzon) in Northern part of Turkey has been studied. In Balcılı, the mineralization is hosted by the tonalitic and granodioritic plutonic rocks. These type of rocks are cut by the prophiritic and felsitic andesites-quartz andesites, dacites, diabase dykes and veins or veinlets type of quartzs. Although there is no clear geological age for emplacement of the Balcxli granitoids, a number of researchers agree with the Upper Cretaceous age based on their field obsevations. The Güzelyayla porphyry type cooper mineralization is hosted by the volcanic and subvolcanic porphiritic andesites and dacites. The grain size of the rocks change from north to south in accordance with the chemical compositions of volcanoplutonics and reaches to the gronodiorites and adamellites in the south of the investigated area. Major element geochemical results reveal that the Balcılı granitoids are derived from the calc-alkali magmas. In Balcılı, the magmatic rocks are relatively in sodic and calcic character ;' the alkali-lime index for granitoids is approximately 63. Metaluminous and peraluminaus granitoids spreaded as the transition types as classified by the I and S-type granitoids. As the potassic alteration is widespread in this area, there is an excess potassium content in the rocks which results from the secondary biotites. This is believed to be affected by the variation of the original I-type granitoid to the S-type granitoid. The Balcılı plutonic rocks are also named as the magnetite series granitoids. Major element geochemical results indicate that the Güzelyayla volcanic and sobvolcanic rocks are generated from the calc-alkali magmas. Dacites are the main rock group in the investigated area. Their chemial compositions vm

Abstract:
A GENETICAL INVESTIGATION OF BALCILK ARTVİN) AND GÜZELYAYLA( TRABZON) COPPER-MOLYBDENUM OCCURRENCES IN THE METALLOGENIC PROVINCE OF EASTERN PONTID SUMMARY In the folloujing dissertation, turn porphyry copper mineralization areas Balcılı (Artvin ) and Güzelyayla (Trabzon) in Northern part of Turkey has been studied. In Balcılı, the mineralization is hosted by the tonalitic and granodioritic plutonic rocks. These type of rocks are cut by the prophiritic and felsitic andesites-quartz andesites, dacites, diabase dykes and veins or veinlets type of quartzs. Although there is no clear geological age for emplacement of the Balcxli granitoids, a number of researchers agree with the Upper Cretaceous age based on their field obsevations. The Güzelyayla porphyry type cooper mineralization is hosted by the volcanic and subvolcanic porphiritic andesites and dacites. The grain size of the rocks change from north to south in accordance with the chemical compositions of volcanoplutonics and reaches to the gronodiorites and adamellites in the south of the investigated area. Major element geochemical results reveal that the Balcılı granitoids are derived from the calc-alkali magmas. In Balcılı, the magmatic rocks are relatively in sodic and calcic character ;' the alkali-lime index for granitoids is approximately 63. Metaluminous and peraluminaus granitoids spreaded as the transition types as classified by the I and S-type granitoids. As the potassic alteration is widespread in this area, there is an excess potassium content in the rocks which results from the secondary biotites. This is believed to be affected by the variation of the original I-type granitoid to the S-type granitoid. The Balcılı plutonic rocks are also named as the magnetite series granitoids. Major element geochemical results indicate that the Güzelyayla volcanic and sobvolcanic rocks are generated from the calc-alkali magmas. Dacites are the main rock group in the investigated area. Their chemial compositions vmchange from the low-potassium dacites to high-potassium dacites. In Güzelyayla, the volcanoplutonic rocks are in sodic and calc-alkali character. Their alkali-lime index value is approximately 58. I-type granitoid features are the prevailing charecteristic of andesites and dacitic rocks. As the distribution of potassic alteration in this area is limited, the tendency of rocks to the S-type character is restricted. The narrow distribution found in potassic zone is believed to have an important part on this occurence. In Güzelyayla porphyry copper mineralization area, the magmatic rocks represent the magnetite series which reflects the more oxidized environment than the ilmenite series granitoids, The Balcılı granitoids are derived from the pacific type magma with respect to their Niggli parameteres. This result is also in accordance with the major elements. According to the parameter evaluations the magmatic rocks distribute in the semisalic, isofalic and semifemic regions indicating that the multiple intrusives exist in this area, as it was also extensive in many other prophyry copper deposits. Granitoids classified in the alkali intermediate region also show alkali magma in character. Discounting some of the Niggli values by a computer program, the plutonic rocks in Balcılı area are found to orginate from a calc-alkali granitic magma. The Güzel yayla volcanoplutonic rocks are generated from the pacific type magmas. Appreciation of the Niggli parameters indicates that the investigated area rocks arised from the salic, isofalic and semifemic magmas. A computer program written for these purpose evaluating the alkali and f erromagnesien Niggli values, show the alkali intermediate rocks to be derived from a calc-alkali granitic magma. Lineer trend surface of the dif f erantiation index in the Balcılı granitoids increases from the Northeast to the Southwest direction and the dip is to the Southeast. Quintic polynomial trend surface shows that there is a zonal structure among the tonalites through granites, depending upon the chemical compositions of rocks. Combination of dif f erantiation, crystallization and solidification indexes in the Güzelyayla volcanoplutonics indicate that there are mainly two different solidification trends, i.e. the crystallization in this area continued at some intervals. Systematic variations between Rb-Ba and Sr-Rb are consistent with a dif f erantiation model in the Balcılı IXporphyry copper mineralization area and show trends typical of plagiocl ase-biotite f ractination. In chondrite normalized spider diagram the spectrum of trace elements shows similar trends for granitoids that were developed in island arcs and continental margins. Granites are enriched in large ion litophile elements except Sr, compared to the granodiorites and tonalites. In the studied area rocks, cerium (LREE) is enriched in accordance with the spectrum of an island arc or a continental margin granitoid wheares lanthanum is marginally depleted. High field strenght elements (Ta,l\lb, Ti, Y) except Zr, are enriched in plutonic rocks and show that they may be affected by within-pate mantle sources. In tectonic discrimination diagrams, the Balcılı granitoids accumulate in the volcanic arc granitoids region. From the paint of view of the arc maturity they range from dominantly normal continental arc to mature continental arc environments. Systematic covariations between Rb-Ba and Sr-Rb are harmonious with a dif f erantiation model in the Güzelyayla prophyry copper mineralization area, typical plagioclase-biotite fractination trend was observed as it was in the Balcılı field. There is a consistent relationship between the chondrite-normalized trace element spectrum and an island arc or a continental margin granitoid spectrum. The barren dacites are - enriched in accordance with the mineralized dacites and andesites, particularly in terms of the large ion lithophile elements. The other high field strenght elements (Ta, Nb, Ti, Y) except Zr, show a richer trend compared to the island arc granitoids. The Güzelyayla volcanoplutonic rocks accumulate in the volcanic arc granitoids on tectonic discrimination diagrams. In terms of the arc maturity they range from the primitive to the dominantly continental arc environments. Representative microprobe amphibole analysis and the structural fromula recalculated on the basis of 23 oxygen cations show that calcic amphiboles in the Balcılı granitoids exhibit magnesio-harnblende composition. The crystallization pressures of the Balcılı granitoid considering the total cationic, aluminum content of hornblende has been calculated as 3.D2 - D.5 kbar using the calibration of 3ohnson and Rutherford. The Balcılı magmatic rocks have been equilibrated under this pressure and a temperature of 791- 75 C using the geothermometer equations of Blundy and Holland. In the Güzelyayla volcanic and subvolcanic rocks the calcic amphiboles are in magnesio-hornblend composition. The volcanoplutonic rocks have been crystallized according to the total cationic aluminum content of hornblende at 2.72- G. 5 kbarpressures at an equilibration temperatures of 6B2-75 C. The Balcılı granitoids distribute in Feiss's mineralized pluton region when A/CNK ratio in molar quantities is plotted versus 5i0" content. The most important component in this diagram is A1"D". Unmineralized but, altered granitoids are generally enriched uiith aluminum but depleted with alkalies. A new seperation line was proposed instead of Feiss's seperation line in order to seperate the mineralized pluton from the unmineralized pluton more accurately and eliminate the undesirable situations encountered. The validity of proposed seperation line has been spreaded particularly over the barren Güzelyayla dacites. In this study, another seperation curve was developed to seperate the porphyry copper deposits in the porhyry molybdenum rich and porphyry copper rich fields in the copper-molydenum-gold triangular diagram. ' Using this diagram it has been noticed that the Balcilx granitoids are widespread in the porphyry molybdenum rich sector. On the other hand, the Güzelyayla prophyry copper mineralization classified as in the porphyry copper sector indicates the different mineralization character from the Balcılı area. Copper mineralization occurs ^s disseminations and veinlets in the Balcılı granitoids. There is almost no copper mineralization in quartz veins and veinlets that cut the granitoids. Molybdenum however, is found mainly in two forms. It is observed in granitoids as disseminations and in quartz as veins and veinlets. Pyrite, chalcopyrite, malachite, azurite, molybdenite, magnetite, hematite, ilmenite and pyrrhotite are the primary ore minerals. The polished sections did not reveal the copper accompanied with molybdenum. Copper mineralization is observed mainly in two forms in the volcanic and subvolcanic Güzelyayla rocks. Fracture filling chalcapyrites in dacites are widespread in this area. Chalcopyrite in the second situation accompanies pyrite and molybdenite depending upon the intensive silicif ications. Micro veinlets chalcopyrite related with the silicif cation is the characteristic. feature :o'f the investigated area. The Güzelyayla porphyry copper mineralization is distinguished from the Balcili area by its variety of ore minerals. Pyrite, chalcopyrite, bornite, chalcosine, covelline, neodigenite, cubanite, tetrahedrite, cuprite, tenorite, native copper, azurite, malachite, molybdenite, pyrrhotite, pentlandite and sphalerite are the primary ore minerals;- XIThe existance of mainly three alteration zones in the Balcılı mineralization area has been identified based on the 140 thin section determinations. They change from potassic through phyllic to propylitic alteration zones from inward to outward. Potassic alteration is characterized by the boucle type fine grained secondary biotites. This zone is observed within be granodiorites and tonalites. It comprises an important part of copper molybdenum mineralization. The potassic zone passes to the phyllic zone with the increase of the sericite and pyrite. In addition to the chloritization, phyllic zone passes to the propylitic zone upon observing the epidote. Microprobe studies on representative primary and secondary biotites and the structural formula recalculated on the basis of 22 oxygen cations show that biotites in potassic zone exhibited a tendency phologopite in character. Based on the 1 75 thin sections mainly three alteration zones mere determined respectively potassic, phyllic and propylitic from inward to outward in the Güzelyayla mineralization area. Potassic alteration characterized by the presence of secondary biotites, occurs as pseudomorphs after igneous amphiboles and as a variable flooding of the porphyry groundmass. In this zone the volcanic and subvolcanic dacites are widespread. Silicif ication is the other typical feature of potassic zone. Phyllic zone is characterized by the sericitization, pyritization and chloritization in biotites. Propylitic alteration generally, found in the basalts, basaltic andesites and barren dacites. Epidote and pyrite are the most important part of this zone. Electron probe studies on primary and secondary biotites in potassic zone indicate that biotites are annite in character. Copper shows strong lognormal distribution character in the Balcxli granitoids. Molybdenum with the two different populations also exhibits lognormal distribution. Classicical anomaly calculations indicate that the probable anomaly values for copper, molybdenum, zinc and lead are 754, 555, B9 and 14 ppm respectively. There is a negative correlation between copper and molybdenum in the Balcılı mineralization arae. This is an another statement of inconcurrence of copper and molybdenum. Similar strong lognormal distributions for copper, molybdenum, zinc and lead are valid for the Güzelyayla porphyry copper mineralizations. According to the classical anomaly calculations, the probable anomaly for capper, molybdenum, zinc and lead are 3120,636,320 and 14 ppm, respectively. The relationship between copper and molybdenum yield a pozitive trend with a correlation coefficient of 0.28. The indicated value is also an xiievidence far the concurrence of copper and molybdenum. Dne of the most pouierfull multiple geochemical data evaluations, the trend surface analysis, has been applied to the Balcxli area for studying the copper concentrations. The analysis was applied to the quintic level. Linear trend surface analysis shows that there is a linear variation in Northeast-Southwest direction and increasing copper concentrations dip to the Southeast. Quadratic trend surface analysis emphasizes that a pozitive ellipsoidal plane in which long axis in Northeast- Southwest and short axis in Northwest-Southwest directions has an important role on minenalization. Increasing the level of polynomial equations did not change the outlines of concentration but pointed out the local negative ellipsoidal planes. Quintic residuel trend surface analysis shows that there are roughly four copper anomaly fields in the investigated are. It has been determined that there was a linear variation trend in Northeast-Southwest dierction and increases to the Southeast for copper concentration in the Giizelyayla pbrhyry copper mineralization area. Structural controlled mineralization was not changed its contours when the level of polynomial equation was increased up to the fifth degree. Quintic residuel trend surface analysis points out the four anomaly fields for copper in the studied area. Principal component analysis indicates that mainly two components in the Balcılı porphyry copper area played an important part in mineralization. Component 1, comprises the 79% of total variance of original data. Copper is the most important element with a pozitive principal component loading of Q.99. The second important element in Component 1 is the molybdenum with the principal component loading of 0.2. Component 2, includes the 21% of total variance of original data. The most important element in component 2 is molybdenum with the principal component loading of 0.99. Copper is the second important element with the component loading of 0.1. Principal component analysis applications in the Giizelyayla porphyry capper area showed nearly similar results as in the Balcılı area. Component 1, includes the 74% of total variance of original data. Copper is the most important element in component 1 with the component loading of 0.90. Molybdenum follows the copper with the 0.42 component loading in pozitive trend. Component 2, comprises the 26% of total variance of data and the most important element is molybdenum with the 0.91 pozitive component loading. Copper shows a negative component loading of -0.41. xxi iLinear discriminant analysis between the Balmılı and Giizelyayla porphyry copper mineralization areas yields an equation which discriminates the copper and molybdenum populations with a linear line in North 40 East direction. About 75% of the original values in the Balcılı area was seperated to the centered index. Original data of the Güzelyayla area are seperated about in the 83% of ratio according to the centered index. Correlation of the results together with the other statistical evaluations showed that the Güzelyayla area is the most promising field among the areas studied. xiv