Alteration Mineralogy and Geochemistry of the Hydrothermally Altered Rocks of the Kutlular (Sürmene) Massive Sulfide Deposit, NE Turkey

Authors : EMEL ABDİOĞLU MEHMET ARSLAN

Pages : 139-162

Doi:10.3906/sag-1203-78

View : 19 | Download : 6

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :Volcanogenic massive sulfide deposits accompanying the Upper Cretaceous felsic rocks in the intra-arc rift zone of the Pontide palaeo-arc are common in the NE Turkey. One of them, the Kutlular insert ignore into journalissuearticles values(Sürmene, Trabzon); deposit, is an abandoned mine within the Upper Cretaceous mafic, felsic volcanics and subvolcanic rocks. Detailed mineralogical and geochemical studies indicate the presence of hydrothermal alteration zones around the Kutlular deposit; these alteration zones are represented by silicification-pyrite-illite zone, illite-silicification zone, illite/smectite-silicification zone, smectite zone accompanying kaolinite and halloysite in the dacitic pyroclastics, and additionally chlorite zone in the mafic volcanics. Lithogeochemical data indicate that the footwall dacitic rocks insert ignore into journalissuearticles values(Zr/Y= 1.39-16.39, La/Yb= 0.14-9.57); and hanging-wall basalts-basaltic andesites insert ignore into journalissuearticles values(Zr/Y= 2.13-5.65, La/Yb= 1.16-5.00); are transitional between tholeiitic and calc-alkaline in character. The trace element patterns of the rocks show considerable LILE enrichment insert ignore into journalissuearticles values(K, Rb and Ba); and depletion in Sr and Ti relative to N-type MORB. Chondrite-normalized REE patterns of the footwall show pronounced HREE enrichment. The Kutlular footwall and hanging wall alteration zones have several geochemical characteristics that show systematic changes with increasing proximity to ore body such as Na depletion as well as elevated alteration index insert ignore into journalissuearticles values(AI); and chlorite-carbonate-pyrite index insert ignore into journalissuearticles values(CCPI);. Generally, hanging-wall mafic volcanics and footwall rocks have high CCPI insert ignore into journalissuearticles values(chlorite-carbonate-pyrite index); values, indicating the importance of chlorite and pyrite formation in these rocks. Calculated mass changes in the footwall dacites commonly are large, and result from major silica mass transfer insert ignore into journalissuearticles values(-9.11 to 99.68 g/100 g rock);. Mass-change calculations indicate that CaO + Na2O + MgO were leached from the rocks by hydrothermal solutions, whereas large amounts of hydrothermal iron were added. Hanging wall basalt and basaltic andesite shows mass changes that are generally much smaller than in the footwall.
Keywords : hydrothermal alteration, clay minerals, massive sulfide deposit, eastern Pontides, Turkey