Review of the Cambrian Pampean orogeny of Argentina; a displaced orogen formerly attached to the Saldania Belt of South Africa?

MARK FANNING, C.; PANKHURST, ROBERT J.; BALDO, EDGARDO G.; CASQUET, CÉSAR; MORALES, MATIAS M.; GALINDO, CARMEN; MORALES, MATIAS M.; DAHLQUIST, JUÁN A.; GALINDO, CARMEN; DAHLQUIST, JUÁN A.; MURRA, JU�A.; RAPELA, CARLOS W.; VERDECCHIA, SEBASTIÁN O.; MURRA, JU�A.; RAPELA, CARLOS W.; VERDECCHIA, SEBASTIÁN O.; MARK FANNING, C.; PANKHURST, ROBERT J.; BALDO, EDGARDO G.; CASQUET, CÉSAR

EARTH-SCIENCE REVIEWS

ELSEVIER SCIENCE BV

Año: 2017 p. 209 - 225

0012-8252

The Pampean orogeny of northern Argentina resulted from Early Cambrian obliquecollision of the Paleoproterozoic MARA block, formerly attached to Laurentia, with theGondwanan Kalahari and Rio de la Plata cratons. The orogen is partially preservedbecause it is bounded by the younger Córdoba Fault on the east and by the Los TúnelesOrdovician shear zone on the west. In this review we correlate the Pampean Belt withthe Saldania orogenic belt of South Africa and argue that both formed at an activecontinental margin fed with sediments coming mainly from the erosion of theBrasiliano?Pan-African and East African?Antarctica orogens between ca. 570 and 537Ma (Puncoviscana Formation) and between 557 and 552 Ma (Malmesbury Group)respectively. Magmatic arcs (I-type and S-type granitoids) formed at the marginbetween ca. 552 and 530 Ma. Further right-lateral oblique collision of MARA betweenca. 530 and 520 Ma produced a westward verging thickened belt. This involved anupper plate with high P/T metamorphism and a lower plate with high-gradeintermediate to high P/T metamorphism probably resulting from crustal delamination orroot foundering. The Neoproterozoic to Early Cambrian sedimentary cover of MARAthat was part of the lower plate is only recognized in the high-grade domain along witha dismembered mafic?ultramafic ophiolite probably obducted in the early stages ofcollision. Uplift was fast in the upper plate and slower in the lower plate. Eventually theSaldania and Pampean belts detached from each other along the right-lateral Córdoba Fault, juxtaposing the Rio de la Plata craton against the internal high-grade zone of thePampean belt.