Field Trips

Rize-Çayeli VMS Deposit

 

Çayeli Cu-Zn mine is located in the province of Rize near the Black Sea coast of northeastern Turkey. Bimodal-felsic-type deposit is related to fault-controlled subsidences and circular structures (caldera?) that developed in a volcanic-arc setting. Çayeli mine is a Late Cretaceous volcanogenic massive sulfide deposit and at the contact between altered footwall felsic volcanics and hanging wall mafic volcanic  rocks. The footwall rocks (approximately 600 m thick) consist of felsic and basic lavas and related autoclastic facies. The hanging-wall stratigraphy consists dominantly of andesite lavas and related fragmental rocks. The stratigraphy is cut by dacites and diabase dikes.


 

The extention of mineralization into directly overlying sequences in which a variety of foraminifera indicates Turonian to Santonian as a upper limit for sulfide accumulation. The deposit, which has proven and probable reserves of about 24 Mt, is currently being mined. At the Çayeli mine, mineralization occurs as a single sulfide lens with a small stockwork zone. The ore body has a known strike length of over 650 meters extends to a depth of at least 560 meters and varies in thickness from a few meters to ~80 meters averaging ~20 meters. Average dip is ~60 degrees to the N-NW. It consist of sea-floor massive and sub-sea floor stockwork sulfides. Mineralization includes pyrite, chalcopyrite, sphalerite and fahlore and lesser amount of galena, bornite and tetrahedrite. Massive ore is classified into yellow ore, black ore and clastic ore. Development of this mine began in early 1990 and a total of 15 million tonnes were produced to the end of 2012, at an average grade of 4.03 percent Cu and 6 percent Zn. Average Au is 1,2 gr/t and Ag values reach up to 150 gr/t. Mine is expected to operate until at least 2018.

 

Erzurum-Ispir Porphyry Cu-Mo Deposit


The Ulutaş Cu–Mo prospect lies within the Ispir batholith Based on drill-hole data, the total reserves were estimated at 73.6 Mtat a grade of 0.31% Cu and 0.022% Mo (Giles, 1973; Soylu, 1999; Yiğit,2009).Porphyry type Cu–Mo mineralization at the Ulutaş prospect is hosted by granite porphyry and quartz porphyry of the Ispir batholith,which is a calc-alkaline multi-phase plutonic complex varying from granite through quartz diorite to syeno-diorite. The oldest units exposed in the northwestern part of the Ulutaş areaare Paleozoic–Lower Mesozoic metamorphic rocks. The metamorphic basement is covered by strongly folded, weakly metamorphosed Cretaceous lava flows of dacitic to rhyolitic composition and pyroclastic rocks with intercalations of laminated mudstone, and shale (Giles, 1973;Taylor and Fryer, 1980). The basement units and volcano-sedimentary sequence are intruded by Ulutaş intrusions that form an erosion window in the Eocene units, comprising andesitic to basaltic lava, tuff andagglomerate with marl, conglomerate, sandstone and limestone intercalations(Giles, 1973; Taylor and Fryer, 1980).A granite porphyry hosting Cu–Mo mineralization exposed in the northern part of the area represents the largest intrusive unit in theregion. It is characterized by a pronounced porphyritic texture at the outcrop scale. Central parts of the granite porphyry are characterized by intrusions of NE-trending, steeply dipping quartz porphyry dykes or stocks, with a porphyritic texture with phenocrysts of embayed quartz and a fine-grained groundmass of quartz and highly sericitized plagioclase. Both granite porphyry and quartz porphyry are crosscut by dioritic, andesitic dykes hosting pyrite–chalcopyrite veinlets (1 to2 mm), The granite porphyry contains micro-granular, roughly oval medium to dark gray dioritic enclaves, which have sharp contacts with their host. All units are overlain by Pleistocene to recent glacial debris and alluvial sediments (Giles, 1973).Porphyry-type mineralization in the Ulutaş area consists of stock work veins and NW-striking quartz veins,with disseminated chalcopyrite ealong the vein systems, and molybdenite within the 1–2 cmt hick quartz veins (Soylu, 1999).

 

Trabzon- Maçka- Güzelyayla Porphyry Cu-Mo Deposit


Güzelyayla deposit, the first explored porphyry type bed in the region, is located about 50 km south of Trabzon province. The mineralization is related to the andesitic-dacitic volcanic units and porphyritic granite intrusions cutting these units. The mineralization is observed in two types: network vein systems and scattered type mineralization. The main minerals of the mineralization are chalcopyrite, pyrite, rutile, pyrrhotite and molybdenite. It is observed that late-stage molybdenite-quartz veins that cut stockwork minerals are very rich in terms of molybdenite. In addition, chalcopyrite, covellite and digenite are observed as supergene enrichment. Three main types of alteration phases, potassic, sericitic and propilitic, related to mineralization have been identified in the studies carried out to date in the region.

 


Mineralization is related with 81.4 ± 1.1 my. (Upper Cretaceous) aged calc-alkaline magmatism. The presence of relic zircons in the granitic units (about 300 my.) indicates that this magma was exposed to high levels of crustal contamination.

 

Gümüşhane-Mastra Epithermal Au Deposit


Mastra Gold Mine is located about 90 km south east of Trabzon province, between the Mescitli, Kalaycıoğlu and Dibekli villages of Gümüşhane province, and around Demirkaynak (Mastra) village.Around the Mastra area The Liassic volcanoclastics, Lower Cretaceous limestones, Upper Cretaceous aged flysch and Eocene volcanics, Eocene sedimanter units and Quaternary units are observed from bottom to top. Mineralization’s in the region are observed in Eocene aged porphyritic andesites and contacts. Southern part of the Mastra deposit there are D-B oriented thrust faults that deform the sedimentary rocks to the north. These faults have no direct relation with the formation of mineralization. These faults are thrusts and reverse faults that result in the pushing over the sedimantery rocks to the Eocene aged andesites and pyroclastics.


 

 

The Mastra gold deposit is hosted by altered basaltic-andesitic rocks of the Eocene Alibaba formation. The deposit occurs within quartz veins in a fault zone dipping 65-80o towards 20-40o. The veins are about 2,5 km’s long and a few cm’s to 5 m’s wide. Native Au, Ag, pyrite, chalcopyrite, sphalerite, sulphosalts and galena are the main ore minerals with minor amounts of secondary digenite, covellite, chalcosite, hematite and limonite. Quartz, barite, adularia, calcite, cerussite, gypsum, sericite, and clay minerals are the gangue minerals. Quartz is by far the most abundant of the gangue minerals and the main constituent of the veins. Due mainly to the conditions of mineral precipitation, various types of crystallisation, growth and replacement textures are present in the quartz veins. Among such textural features are massive, comb, crustiform, coquade, brecciated, breccia-fill, mosaic, flamboyant, ghost-sphere, saccaroidal, and lattice bladed textures, indication of epithermal conditions (Aslan ve Akçay, 2013)

In the  Mastra gold mine between 1992 and 2014 years, 700 drillings with a total of 12000 meters were made. Total reserve of the mine (measured+indicated+inferred) is 30 tons Au and 8 tons Ag. Between 2009 and 2014, a total of 18.5 tons of Au and 5.5 tons of Ag were produced.


Ordu-Ünye-Fatsa Clay Deposit


Different types of clay occurrences are abundantly present in the area within volcanic province of Eastern Pontide (NE Turkey), These occurrences vary depending on alteration types as well as on the composition of parent volcanic products.  In the Ünye-Fatsa (Ordu), the base of the area is characterised by Late Cretaceous aged Tirebolu Formation, consisting of brown, grey-white, greenish, pinkish coloured, locally columnar jointed trachyte, trachyandesite and their pyrociastic rocks. The formation overlain conformably by Late Cretaceous-Palaeocene aged Akveren Formation, containing yellowish white coloured, thin-medium bedded and grey coloured, medium-thick bedded limestone, clayey limestone and tuffite alternations. This unit overlain unconformably by Eocene aged Kumru Formation, including sandstone, sandy limestone, marl, siltstone, claystone and carbonatebearing sandstone (Abdioğlu and Arslan 2002).

 

 

Bentonitic clay deposits are distributed over a 110 km2 area. This bentonites contain a range of residual minerals and textures derived from a variety of pyroclastic parent rocks and essentially monomineralic smectite and display no vertical or lateral zoning as described for hydrothermal alteration (Abdioğlu and Arslan 2005). The total indicated reserves of the deposits in this area is over 2,5 milion (2644000) tones of bentonite (MTA, 2010). Largest two deposits Kavaklar and Tavuklu-Gölüceğiz deposits contain 743.000 and 812.000 tons of bentonite respectivly. In recent years, the prominence in Ünye-Fatsa (Ordu) regions has been increasingly exported as white bentonite. Countries such as Greece, Italy, Germany, which have the possibility of shipping with low shipping cost, sell white bentonites imported from Eastern Black Sea to world markets.