Detrital zircon ages of the San Miguel marble, Tandilia Belt basement: Constraining the Paleoproterozoic Lomagundi-Jatuli Event in the Río de la Plata Craton

Abstract

The San Miguel marble is one of the only two carbonate rocks identified in the Paleoproterozoic basement of the Tandilia Belt (Argentina) and records the Lomagundi-Jatuli Event. The marble is scarcely limited in time and represents an opportunity to learn more about the geological processes that occurred during the Precambrian in the southern sector of the Río de la Plata Craton and also about the evolution of the processes that took place during the Paleoproterozoic at the global level. This work presents the first U-Pb LA-ICP-MS determinations performed in detrital zircon grains of the San Miguel marble. The results indicate three main age groups that geochronologically constraint the sedimentary and metamorphic processes involved in the genesis of the marble, which are in accordance with the principal stages of the tectonic evolution defined for the Tandilia Belt basement. The first group, between 2543 ± 23 Ma and 2358 ± 22 Ma, represents sedimentation in the Siderian marine basins. The second group, between 2306 ± 20 Ma and 2215 ± 20 Ma, points out the metamorphic event that occurred in the Rhyacian period during the subduction stage. The third and youngest age group, between 2151 ± 20 and 2017 ± 28 Ma, would be associated with the collisional stage that occurred during the Transamazonian Cycle. In addition, the maximum and the minimum age of sedimentation of 2370 ± 17 Ma and 2297 ± 19 Ma (metamorphism), respectively, locate the San Miguel protolith genesis during a transitional period on the onset of the Lomagundi-Jatuli Event during a post glacial stage (Huronian Glaciation Event).