2ND INTERNATIONAL CONFERENCE TOWARDS SUSTAINABLE DEVELOPMENT (TSD’2018) Drazhnja Ore Belt - Geological overview and 3D interpretation, Kosovo (SE Europe) Presenter: MSc. Bahri Hyseni EurGeol. Mentor Demi Date 03.11.2018

ABSTRACT The Drazhnja deposit is located in the Eastern Kosovo, 23 km northeast from Prishtina, in the external zone of the Trepca Mineral Belt (The Trepca Belt of Pb+Zn+Ag mineralization is located within the NNW-SSE trending Vardar zone). The area belongs to the western margin of the Lece massif and is composed of andesite-dacite volcanic and pyroclastics of the Late Mesozoic-Early Tertiary age. The Lece intrusive complex has intruded a folded Cretaceous sedimentary sequence, as well as metamorphosed Paleozoic-Mesozoic rocks (mainly schist and carbonates) and small serpentine lenses of Jurassic age. The mineralization has mostly a hydrothermal-metasomatic character and occurs in the form of stock works, impregnations, and also filling fractures in carbonates. Main ore minerals are sphalerite, boulangerite, galena, pyrite and marcasite. About 6 million tonnes of Pb+Zn ore with content above 7 % has been documented. Only Drazhnja mine is presented in this paper.

INTRODUCTION The history of lead and zinc mining in Kosovo is woven into with the history of Kosovo itself. In the modern era, the production of lead and zinc has been synonymous with Trepça. \ Mining activities and smelting of the silver bearing lead-zinc ore in Kosovo has a long history and can be dated back to even pre-Roman times as the relics of tools and diggings show. The British company Seltrust, founded at one stage, operated nine mines in Trepça as shown on the map (Fig. 1). Currently, only five of these have significant remaining resources, although all have the potential for extensions to the known mineralization. The mining and processing infrastructure following the conflict was in a very poor condition. However, after major effort and significant investment, four of the mines have recommenced limited production. The successful industry of the 1960s and the historic mines were founded on the quality of the lead-zinc deposits that occur in the Trepça Mineral Belt running in a NW-SE direction from Kapaonik (Beloberdo) in the north to Batlava (Drazhnja) - Kizhnica in the south.

TREPÇA MINERAL BELT REGIONAL GEOLOGY The linear Trepça “Belt” of lead-zinc mineralization extends for over 80 km in northern Kosovo, and includes numerous mines and occurrences (Figs. 1, 2). Although evidence of mining dates back to the Romans, who were primarily interested in small gold occurrences, modern mining began in 1930 at the Stan Terg lead-zinc mine, which is located on the Trepca stream. The Trepça Belt lies within the NNW-SSE trending Vardar tectonic zone (Fig. 2). The regional structure marks the fundamental suture between the Serbo-Kosovaro-Macedonian Massif, which is underlain by late Proterozoic metamorphic successions, and the Dina rides, which are comprised of Mesozoic ones with typical alpine deformation. The Vardar Zone contains fragments of Paleozoic crystalline schist and phyllite, with unconformable overlying Triassic clastics, phyllites, volcanoclastic rocks and Upper Triassic carbonates. Serpentinized ultrabazik rocks, gabbros, diabases and sediments of the ophiolite association characterize the Jurassic. The Cretaceous sequence consists of a complex series (sometimes described as mélange) of clastics, serpentinite, mafic volcanics and volcanoclastic rocks, and carbonates. The Tertiary (Oligocene-Miocene) andesite, trachyte and latite sub-volcanic intrusive, volcanics and pyroclastic rocks occur at several centres within the Trepça Belt, covering large areas

DRAZHNJA MINE Exploration and mining history The Drazhnje deposit is located in the Eastern Kosovo, 23 km northeast from Prishtina, in the external zone of the TMB (Figure 1). The area belongs to the western margin of the Lece massif and is composed of andesite - dacite volcanics and pyroclastics of the Late Mesozoic-Early Tertiary age. The Lece intrusive complex has intruded a folded Cretaceous sedimentary sequence, as well as metamorphosed Paleozoic-Mesozoic rocks (mainly schists and carbonates) and small serpentine lenses of Jurassic age. The mineralization has mostly a hydrothermal - metasomatic character and occurs in the form of stockworks, impregnations, and also filling fractures in carbonates. Main ore minerals are sphalerite, boulangerite, galena, pyrite, and marcasite. About 4 million tonnes of Pb-Zn ore with Pb + Zn content above 6% has been documented. The analyzed samples came from the Saint George ore body

DRAZHNJE MINERALIZATION The Pb-Zn deposits in Kosovo share a similar mineralogical signature that is typical for a metasomatic-hydrothermal origin. The main ore minerals are galena, sphalerite, pyrite, pyrrhotite, arsenopyrite, and chalcopyrite with various contents of fahlores, and associated with various sulfosalts, like boulangerite, Bi-minerals, Ag-minerals, and native elements. The gangue minerals are quartz and carbonates and, in the Stan Terg mine, also skarn minerals, like hedenbergite, wollastonite, and ilvaite are present. In the Artana deposit, ferrokësterite occurs in veinlets within sphalerite or along growth zones of sphalerite suggesting contemporaneous deposition of both minerals. Galena and chalcopyrite postdate sphalerite-ferrokësterite deposition, From Kizhnica are enriched in chalcopyrite, which postdates sphalerite-ferrokësterite occurs as growth zones or as single small inclusions. In the samples from the Drazhnje deposit, ferrokësterite is rimming and replaces sphalerite in boulangerite-bearing ores.

3D MODELING OF DRAZHNJA MINE In this paper, 3D modeling includes 3D geological object modeling, 3D modeling of ore body grade using a 3D kriging interpolation method, and a 3D modeling of mineralization using an improved IDW interpolation method. The methodology is based on Data Mine software and mathematical methods and includes several steps of processing data depending on the type of data. Some steps require establishing a virtual section based on geological knowledge in order to control the boundary of a geological object, or establishing virtual boreholes by combining statistics with a BP network for 3D interpolation calculation. Other steps such as data interpretation, information extraction, or 3D object model validation require user interaction. To construct an accurate 3D geological model from geological data (e.g., geological maps at different scales, cross-sections and boreholes), it was necessary to develop a methodology that also takes into account magnetic data. Geological maps synthesize geological information but they do not give a complete representation of the subsurface geology. Cross-sections and borehole logs add the third dimension to give a more detailed interpretation of subsurface structure. However, geophysical information was available; for a better constraint on the interpretation of structures and intrusive rocks. By combining contact locations and orientation of geology and geophysical information, 3D geological models were constructed very well.

CONCLUSIONS Drazhnja deposit represents a unique type of polymetallic deposit, located adjacent to few well known Porphyries and Epithermal deposits. Drazhnja is characterized by both Base and Precious Metals economic importance Resources are estimated at 6 Mt @ ~7% Pb-Zn, with downdip and along strike upside Detailed geological mapping and 3D modelling has led to discovery of new potential zones within the known strike of mineralization Detailed explanation will be presented on the on-progress scientific study “Drazhnja Ore Belt - Geological overview and 3D interpretation, Kosovo (SE Europe)”

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