Recurring extensional and strike-slip tectonics after the Neoproterozoic collisional events in the southern Mantiqueira province

Abstract

In Eastern South America, a series of fault-bounded sedimentary basins that crop out from Southern Uruguay to Southeastern Brazil were formed after the main collisional deformation of the Brasiliano Orogeny and record the tectonic events that affected the region from the Middle Ediacaran onwards.We address the problem of discerning the basin-forming tectonics from the later deformational events through paleostress analysis of more than 600 fault-slip data, mainly from the Camaquã Basin (Southern Brazil), sorted by stratigraphic level and cross-cutting relationships of superposed striations, and integrated with available stratigraphic and geochronological data. Our results show that the Camaquã Basin was formed by at least two distinct extensional events, and that rapid paleostress changes took place in the region a few tens of million years after the major collision (c.a. 630 Ma), probably due to the interplay between local active extensional tectonics and the distal effects of the continued amalgamation of plates and terranes at the margins of the still-forming Gondwana Plate. Preliminary paleostress data from the Castro Basin and published data from the Itajaí Basin suggest that these events had a regional nature.

Tectono‐Metamorphic Evolution of the Central Ribeira Belt, Brazil: A Case of Late Neoproterozoic Intracontinental Orogeny and Flow of Partially Molten Deep Crust During the Assembly of West Gondwana

“…Both Embu and Costeiro domains might represent the hinterland of the Southern Brasilia Belt, connected northward to a stricto sensu intracontinental setting (Araçuaí Belt) between São Francisco and Congo cratons (Fossen et al, 2017;Meira et al, 2015). Accordingly, to our tectonic evolutionary model, a more than 1,500-km-long continuous rift system, active along the southeastern South America during the middle Ediacaran-early Cambrian, indicates an important extensional event in the Mantiqueira Province (Almeida et al, 2010(Almeida et al, , 2012. Small fault-bounded siliciclastic and volcaniclastic basins and voluminous coeval granitic magmatism characterize this rift system and imply that all the terranes involved in the collisional stages of the Brasiliano Orogeny in the Mantiqueira Province were united in a single plate already at~650-600 Ma (Almeida et al, 2010;this work).…”

“…The northern limit corresponds to the inflection of large-scale lineaments, roughly coincident with the transition from strike-slip to thrust-dominated tectonic regimes (e.g., Egydio-Silva et al, 2005;Vauchez et al, 1994). The geological units of the Ribeira Belt include Paleoproterozoic crystalline inliers, Mesoproterozoic and Neoproterozoic metasedimentary sequences, voluminous Neoproterozoic granitic batholiths, and small Ediacaran/Cambrian volcanosedimentary basins (Almeida et al, 2010(Almeida et al, , 2012Campanha & Sadowski, 1999;Heilbron et al, 2008;Janasi et al, 2001Janasi et al, , 2009Siga et al, 2011;Silva et al, 2005;Vlach et al, 2011). All these units are variably reworked by the strike-slip shear system associated with the Neoproterozoic Brasiliano Orogenic Cycle.…”

“…First-order inconsistencies in the model of recurrent microplate collisions in the Ribeira Belt and the closure of an ocean in the Araçuaí Belt include (a) the nonagreement, in a broader sense, between the geological records of upper crustal (e.g., Ediacaran-early Cambrian rift-related basins) and middle-lower levels (e.g., terrane collisions and accretion; e.g., Almeida et al, 2010Almeida et al, , 2012Heilbron et al, 2013), and (b) the…”

Proveniência e paleocorrentes de conglomerados e arenitos do Grupo Santa Bárbara (Ediacarano) no Vale do Piquiri, Sub-bacia Camaquã Oriental, RS: implicações tectônicas

“…(A) bacias sedimentares do fim do Neoproetrozoico e início do Paleozoico na porção sudeste da Plataforma Sul-Americana; (B) mapa geológico esquemático das unidades neoproterozoicas e eopaleozoicas do Rio Grande do Sul, com destaque para as unidades que constituem o Supergrupo Camaquã. A B Fambrini et al, 2001;Fambrini, 2003;Fambrini e FragosoCesar, 2006;Fambrini et al, 2005Fambrini et al, , 2007Fambrini et al, , 2011Fambrini et al, , 2014Almeida et al, 2009Almeida et al, , 2010Almeida et al, , 2012, também interpretada como um sistema anorogênico (Fragoso-Cesar et al, 2002, 2003Fragoso-Cesar, 2008).…”

Modelagem termodinâmica de fusão parcial e metamorfismo em condições de fácies granulito: exemplo do complexo Itatins, SP

“…The development of pull-apart basins along the mobile belt occurred during the transition from Proterozoic to Phanerozoic times (e.g. Almeida et al, 2012). Nowadays it is considered that the southern portion of the Ribeira Belt comprises several different tectonostratigraphic terranes (e.g.…”