The lower paleozoic plutonic-volcanic connection in the eastern magmatic belt, SW Gondwana, northern Puna Argentina

Abstract

The relationship between plutonic and volcanic rocks is key to understanding the geochemical evolution of silicic magma systems. In order to untangle the plutonic and volcanic connection and contribute to the reconstruction of the Lower Paleozoic Arc at the SW Gondwana margin, in this study we describe the Sey Plutonic-Volcanic Unit, located in Eastern Magmatic Belt, northern Puna, Argentina. Additionally, we present zircon U-Pb ages by LA-MC-ICP-MS and geochemical data. The studied unit is comprised of monzogranites, granodiorites, gabbros, dacites, and rhyodacites, cropping out as plutonic bodies, laccoliths, sills, subaqueous domes, and lava flows. Following the analyses of the different zircon age populations, the granodiorites bodies crystallized at ∼480 Ma, the monzogranites followed at ∼470 Ma. Lastly, the rhyodacites crystallized at ∼446 Ma. Afterward the age groups analyses, in the Eastern Magmatic Belt, northern Puna, the magmatic activity started from ∼520 to 515 Ma until ∼446 Ma, with the magmatic activity peak at ∼485-475 Ma. The age groups, besides with the geochemistry data, isotope, and magma source similarities of the Eastern Magmatic Belt, both north and southern Puna, underline that the formation of the granitoids and volcanites in the Eastern Magmatic Belt was perhaps through a long-lived magmatic event, represented by low and high volume magmatic episodes.