Early Cambrian multiple-sourced plutonism in the Eastern Sierras Pampeanas, Córdoba, Argentina: Implications for the evolution of the early Paleozoic Gondwana margin

TIBALDI, ALINA M.; OTAMENDI, JUAN E.; DEMICHELIS, ALEJANDRO H.; BARZOLA, MATÍAS G.; BARRA, FERNANDO; RABBIA, OSVALDO M.; CRISTOFOLINI, EBER A.; BENITO, MARÍA P.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2021 vol. 106

0895-9811

Four major igneous suites with differentgeochemical characteristics are identified in the accretionary complex of thePampean orogeny from the southern Sierras de Córdoba, Argentina.Crystallization ages of gabbroic and trondhjemitic plutonic rocks are Early toMiddle Cambrian. The plutonic suites include mafic to intermediate alkalineOIB-like rocks, mafic tholeiitic N-MORB rocks, transitional mafic rocks, andminor trondhjemitic rocks with adakitic geochemical signature. The multipleigneous suites are spatially and temporally related to what revealssimultaneous tapping of distinct source reservoirs with their respective meltsremaining distinctive from extraction to emplacement at middle crustal depths.The alkaline mafic-intermediate rocks with OIB-like geochemistry were generatedby partial melting of an enriched or metasomatized mantle domain., Tholeiiticmafic rocks with N-MORB geochemical signature came out from a depleted mantlesource. Trace element abundances of the transitional mafic magmas reflectvariable mixtures between OIB-like and MORB-type magmas. Trondhjemitic rocksexhibit geochemical features highlighting their parent melts formed by lowdegree melting of a metasomatized subducting oceanic crust. The most reliablesetting to generate all these diverse magmatic suites at the same time is aconvergent margin where the opening of a slab window followed ridge-trenchinteraction. A corollary is that widespread mafic magmatism enhanced heatadvection and gave rise to extensive intra-crustal anatexis in an accretionarycomplex of crustal extension.