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

Abstract

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

Time lag between metamorphism and crystallization of anatectic granites (Córdoba, Argentina)

“…These sequences are represented by the low-grade metamorphosed turbidites of the Puncoviscana Formation, and their higher metamorphic grade counterparts (schists, gneisses and migmatites) located at the Sierras de Ancasti and Córdoba (Aceñolaza and Aceñolaza, 2007;Omarini, 1999;Rapela et al, 1998;Rapela et al, 2007;Schwartz and Gromet, 2004;Toselli, 1990;Turner, 1960). There is a lack of consensus regarding the tectonic setting of deposition of the Puncoviscana Basin (Casquet et al, 2018). This has been interpreted as either a 1,000km long passive margin along the western margin of Gondwana (Ježek et al, 1985;Schwartz and Gromet, 2004) or a fore-arc basin (Hauser et al, 2011;Rapela et al, 2007).…”

“…They are constituted by N-S trending mountain ranges mostly composed of Neoproterozoic to Devonian metasedimentary and igneous rocks. The main tectonothermal event registered in the Sierras de Córdoba, during the Pampean orogeny, is the so called M2 (Casquet et al, 2018;Guereschi and Martino, 2014;Rapela et al, 1998). This event was linked to an increase in the P-T conditions, due to crustal shortening with thrusts propagating into the fore-arc (Weinberg et al, 2018), leading to an upper amphibolite to granulite facies metamorphism and anatexis.…”

“…This calc-alkaline magmatism is widely exposed in the Sierra Norte de Córdoba and is usually referred to as the Sierra Norte-Ambargasta batholith (Iannizzotto et al, 2013;Lira et al, 1997;Schwartz et al, 2008;Von Gosen and Prozzi, 2010). The U-Th-Pb dating in granitoids from the Sierra Norte-Ambargasta batholith gave crystallization ages between 530 and 537Ma and were linked to the development of a continental magmatic arc in an eastward subduction of oceanic lithosphere down to the western 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 1 2 3 4 5 6 7 8 9 10 51 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Metamorphism and magmatism time lag 3 margin of Gondwana (Casquet et al, 2018;…”

Tectonic controls on deposition in the late Cambrian - Early Ordovician Central Andean Basin (Cordillera Oriental; northwest Argentina) – the first step towards an integrative reconstruction

“…537 Ma (e.g., Aparicio González et al, 2014). This unit was subsequently metamorphosed during the early Cambrian Pampean Orogeny (e.g., Mon and Hongn, 1996;Escayola et al, 2011;Casquet et al, 2018) induced by the oblique transpressive collision of the MARA block sensu Casquet et al (2012) which accreted the Maz, Arequipa, and Rio Apa terranes. Further, the Mesón Group uncomformably overlains the Puncoviscana Formation (Sánchez and Salfity, 1999).…”

Metamorfismo de alto gradiente P/T en la Sierra de Pie de Palo (Sierras Pampeanas, Argentina): modelado de equilibrio de fases minerales e implicancias geodinámicas en el antearco famatiniano

“…La orogenia Pampeana se encuentra representada por un arco magmático calcoalcalino y rocas metamórficas de bajo a alto grado metamórfico de ca. 545-520 Ma (Casquet et al, 2018 y referencias allí citadas) mientras que la orogenia Famatiniana desarrolla un arco magmático de ca. 490-460 Ma (e.g., Pankhurst et al, , 2000 y metamorfismo regional entre 480-440 Ma (e.g., Casquet et al, 2001;Lucassen y Becchio, 2003;Steenken et al, 2006;Mulcahy et al, 2011Mulcahy et al, , 2014.…”