Constraints on the Statherian evolution of the intraplate rifting in a Paleo-Mesoproterozoic paleocontinent: New stratigraphic and geochronology record from the eastern São Francisco craton

Abstract

An integrated approach of stratigraphic analysis and U-Pb age dating reveals some information on the tectonosedimentary evolution of the Statherian cover of the São Francisco craton in the so-called Espinhaço basin (Atlantic shield in eastern Brazil). Here, continental sedimentation patterns, such as alluvial fan, braided-plain and lacustrine facies associations, with associated volcanic rocks are documented in two superposed basin fill-successions, which are defined as the Algodão and Sapiranga Synthems and grouped in the Botuporã Supersynthem. Both studied units consist mainly of conglomerates and cross-bedded sandstones and minor amounts of mudstones, sedimentary breccias, volcanic lava beds and volcaniclastic rocks, which were deposited in a rift basin -the Botuporã rift -during two syn-rifting phases. The Algodão Synthem represents the first rifting phase. The basal synsedimentary conglomerates of this unit were deposited mainly by subaerial debris flows, most likely along and near a rift border fault. The framework of this rock consists of only crystalline rock clasts from the basement and no fragments of volcanic rocks. Detrital zircon grains that were extracted from this facies show ages older than 2.05 Ga. The remainder of the section is dominated by fluvial sandy lithofacies with minor conglomerate lenses and sandstone-mudstone heterolithic lithofacies, which represent distal, waning-flood deposits in a lacustrine environment. The upper section also contains hummocky cross-stratified sandstone lithofacies, which are related to a storm-influenced deposition. On top of the Algodão succession, the volcanic rocks were dated at 1775 ± 7 Ma, which was interpreted as the near final age of the first rift-phase. Representing the second rift-phase, the Sapiranga Synthem shows similar sedimentation patterns to the Algodão Synthem. The Sapiranga Synthem rests directly on the volcanic rocks of the Algodão Synthem, and its basal conglomerates (which are most likely also related to a master fault) contain voluminous clasts of volcanic rocks, sandstones and crystalline rocks. The detrital zircon grains that were extracted from this facies show ages of 1741 ± 14 and 1766 Ma as well older than 2.05 Ga. The volcanic rocks on the upper succession of the Sapiranga Synthem record ages of 1740 ± 10 Ma, which finalized the Botuporã rift evolution. A preliminary geochemical study of volcanic rocks from the Botuporã Supersynthem showed that these rocks are alkaline rocks with high K 2 O/Na 2 O ratios, which belong to an ultrapotassic suite. The low concentrations of MgO wt.% suggest a felsic ultrapotassic character. The Botuporã Supersynthem is unconformably covered by a volcanosedimentary rift-succession of EoCalymmian age -the Pajeú Synthem, which represents the second rifting stage of the Espinhaço basin. Several Statherian-related volcano-sedimentary sequences and anorogenic granitoids occur dispersed in the São Francisco block, which requires a regional geologic model to explain the extensional and magmatism process during ...

Post‐Great Oxidation Event Orosirian–Statherian iron formations on the São Francisco craton: Geotectonic implications

“…The basin in this domain has also undergone inversion during the Brasiliano collage (Danderfer Filho, Lagoeiro, & Alkmim, ). Thrusting of the cover rocks distant from the active plate boundary of the Araçuaí Orogen deformed the Ediacaran units of the Santo Onofre Group and São Francisco Supergroup and interfered with the extensional structures of the Paramim Aulacogen (Danderfer Filho, Lana, Nalini, & Costa, ).…”

Tectonics and sedimentation of the central sector of the Santo Onofre rift, north Minas Gerais, Brazil

“…Danderfer ( Danderfer et al, 2015). Chapada Diamantina (CD), Northern Espinhaço (NE), Central Espinhaço (CE) and Southern Espinhaço (SE).…”

“…Dominguez and Rocha (1989) mapped four depositional systems between the central and northern Espinhaço ranges (from the base to the top): Baixão, Salto, Telheiro and Gentio. According to Danderfer (2000), the Telheiro and Salto depositional sequences correspond to Sítio Novo Group, and the Babinski et al (2012), 5 Costa et al (2014), 6 Sousa et al (2014), 7 Castro (2014), 8 Danderfer et al (2015), 9 Kuchenbecker et al (2015).…”

Registro e análise de estruturas relacionadas com a tectônica extensional do rifteamento Macaúbas na Serra Central, norte de Minas Gerais

“…Na porção ocidental do paleocontinente São FranciscoCongo, no bloco São Francisco, registros de eventos formadores de bacias se estendem do Paleoproterozoico ao Neoproterozoico e compõem o aulacógeno do Espinhaço, que remonta a uma história policíclica de mais de um bilhão de anos (Moutinho da Costa e Inda, 1982;Danderfer e Dardenne, 2002;Danderfer et al, 2009Danderfer et al, , 2015, conforme ilustrado na Figura 1A. Nesse sentido, o aulacógeno do Espinhaço representa uma zona de fraqueza crustal no interior da qual o processo tectônico de formação de bacias recorreu ao longo do tempo de existência de grandes massas continentais, como Figura 1.…”

“…A porção meridional da estrutura aulacogênica, ao sul do paralelo 14°S da Figura 1B, foi fortemente afetada por deformações relacionadas com a orogênese Brasiliana (Neoproterozoico) e passou a integrar o sistema de cavalgamentos da Serra do Espinhaço Meridional na porção ocidental do Orógeno Araçuaí, onde o embasamento é envolvido na deformação da cobertura (Alkmim et al, 2006, conforme ilustrado na Figura 1B. De forma geral, as coberturas do aulacógeno Espinhaço são descritas nos supergrupos Oliveira dos Brejinhos (1,8 -1,5 Ga), Espinhaço (1,5 -1,0 Ga) e São Francisco -Neoproterozoico (Danderfer e Dardenne, 2002;Danderfer et al, 2015). O último registro de formação de bacia é definido pela sucessão siliciclástica do Grupo Macaúbas, interpretada como o preenchimento de um rifte seguido de uma margem passiva (PedrosaSoares et al, 2001(PedrosaSoares et al, , 2011.…”