Origin of the DUPAL anomaly in mantle xenoliths of Patagonia (Argentina) and geodynamic consequences

MAZZUCCHELLI MAURIZIO; CIPRIANI ANNA; HÉMOND CHRISTOPHE; ZANETTI ALBERTO; BERTOTTO GUSTAVO W.; CINGOLANI CARLOS A.

LITHOS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2016 vol. 248 p. 257 - 271

0024-4937

The sub-continental lithospheric mantle of South America has been known for some time to carry the DUPAL isotopeanomaly as seen in volcanics from the Paraná volcanic province. However, this has not allowed discriminatingwhether the DUPAL anomaly is a primary feature of the mantle source or acquired during the upwelling andemplacement of the primary magmas. Wediscovered mantle xenoliths fromthe Tres Lagos location in Patagoniathat carry evidence of percolation bymetasomaticmelts that imparted theDUPAL isotope anomaly signature.Wediscuss amodel that requires four isotope components (LCC,EM2, HIMUandDM) to account for the Sr,Nd and Pbisotope variability of our samples.We propose that upwelling of hot astenosphere during the Miocene could havetriggered the melting of the LCC and EM2 components carrying the DUPAL anomaly, previously entrained in thesubcontinental mantle by subduction. These ascending melts would have then metasomatised the local SCLMcharacterised by DMM and HIMU geochemical affinity generating the hybrid DUPAL-bearing mantle sampledby the Tres Lagos xenoliths.