TY - JOUR

T1 - Mesoproterozoic evolution of the Rio de la Plata Craton in Uruguay: at the heart of Rodinia?

AU - Gaucher, Claudio

AU - Frei, Robert

AU - Chemale, Farid

AU - Frei, D

AU - Bossi, G

AU - Martinez, G

AU - Chiglino, L

AU - Cernuschi, F

PY - 2011

Y1 - 2011

N2 - Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Ri´o de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pe´rez Terrane) in Uruguay. The Parque UTE Group consists of basic volcanics and gabbros at the base (1,492 ± 4 Ma, U–Pb on zircon), carbonates in its middle part and interbedded carbonates, shales and acid volcanics (1,429 ± 21 Ma, U–Pb on zircon) at the top. The Mina Verdu´n Group is made up of rhyolites and acid pyroclastics at its base and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U–Pb LA-ICP MS zircon age of 1,433 ± 6 Ma is reported here for lapilli-tuffs at the base of the Mina Verdu´n Group (Cerro de las Vi´boras Formation). This age shows that the Mina Verdu´n Group immediately postdates the Parque UTE Group, a fact supported by carbon isotope chemostratigraphy. Both units were deformed and metamorphosed between 1.25 and 1.20 Ga, as shown by K–Ar and Ar–Ar ages. This tectonic event affected most of the RPC and led to the accretion of the Nico Pe´rez Terrane to the remainder of the RPC along the Sarandi´ del Yi´ megashear. We report a U–Pb LA-ICP MS zircon age (upper intercept) of 3,096 ± 45 Ma for metatonalites of the La China Complex (Nico Pe´rez Terrane), which yield a lower intercept age of 1,252 Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic detrital zircon ages occurring in Ediacaran sandstones of the RPC. If the RPC is fringed at both sides by Mesoproterozoic, Grenville-aged belts it is likely that it occupied a rather central position in Rodinia. A possible location between Laurentia and the Kalahari Craton, and to the south of Amazonia, is suggested.

AB - Mesoproterozoic volcanosedimentary units and tectonic events occurring in the Ri´o de la Plata Craton (RPC) are reviewed. A belt consisting of volcanosedimentary successions exhibiting greenschist-facies metamorphism is exposed in the eastern RPC (Nico Pe´rez Terrane) in Uruguay. The Parque UTE Group consists of basic volcanics and gabbros at the base (1,492 ± 4 Ma, U–Pb on zircon), carbonates in its middle part and interbedded carbonates, shales and acid volcanics (1,429 ± 21 Ma, U–Pb on zircon) at the top. The Mina Verdu´n Group is made up of rhyolites and acid pyroclastics at its base and top, and Conophyton-bearing limestones and massive dolostones in the middle. A U–Pb LA-ICP MS zircon age of 1,433 ± 6 Ma is reported here for lapilli-tuffs at the base of the Mina Verdu´n Group (Cerro de las Vi´boras Formation). This age shows that the Mina Verdu´n Group immediately postdates the Parque UTE Group, a fact supported by carbon isotope chemostratigraphy. Both units were deformed and metamorphosed between 1.25 and 1.20 Ga, as shown by K–Ar and Ar–Ar ages. This tectonic event affected most of the RPC and led to the accretion of the Nico Pe´rez Terrane to the remainder of the RPC along the Sarandi´ del Yi´ megashear. We report a U–Pb LA-ICP MS zircon age (upper intercept) of 3,096 ± 45 Ma for metatonalites of the La China Complex (Nico Pe´rez Terrane), which yield a lower intercept age of 1,252 Ma. A proto-Andean, Mesoproterozoic belt is envisaged to account for abundant Mesoproterozoic detrital zircon ages occurring in Ediacaran sandstones of the RPC. If the RPC is fringed at both sides by Mesoproterozoic, Grenville-aged belts it is likely that it occupied a rather central position in Rodinia. A possible location between Laurentia and the Kalahari Craton, and to the south of Amazonia, is suggested.

U2 - 10.1007/s00531-010-0562-x

DO - 10.1007/s00531-010-0562-x

M3 - Journal article

VL - 100

SP - 273

EP - 288

JO - International Journal of Earth Sciences

JF - International Journal of Earth Sciences

SN - 1437-3254

IS - 2-3

ER -