Cenozoic porphyry and epithermal systems in the South Armenian Block, Lesser Caucasus, Armenia: new temporal geochemical and petrogenetic constraints

The South Armenian Block (SAB) of the Lesser Caucasus is characterized by abundant Cenozoic magmatism and hosts important Au, Cu and Mo ore deposits. Their emplacement was controlled by dextral strike-slip tectonics initiated during the collision between the Arabian and Eurasian plates. This regional study focuses on the Meghradzor and Amulsar mining districts, hosting epithermal Au deposits, located in the northern and central parts of the SAB, respectively. New geochemical and geochronological results for these sites combined with previous data published for the southernmost Lesser Caucasus aim at providing regional petrogenetic constraints. Based on Hf, Sr and Nd isotope systematics, the magmatism in the Lesser Caucasus is predominantly juvenile with limited crustal contamination. Zircon U-Pb ages range from 48.9 to 21.2 Ma in southernmost Armenia, and from 43.2 to 28.4 Ma in the central to northern part of Armenia. The magmatic rocks exposed in the different mining districts display variable geochemical compositions reflecting various magmatic differentiation and source processes. However, each magmatic series is temporally and spatially associated with an ore deposit. The ultimate goal is to characterize the source and crustal differentiation processes to provide new understanding regarding the regional relationship of the diverse magmatic rocks and the associated ore deposits.