Ediacaran 2,500-km-long synchronous deep continental subduction in the West Gondwana Orogen

Abstract

The deeply eroded West Gondwana Orogen is a major continental collision zone that exposes numerous occurrences of deeply subducted rocks, such as eclogites. The position of these eclogites marks the suture zone between colliding cratons, and the age of metamorphism constrains the transition from subduction-dominated tectonics to continental collision and mountain building. Here we investigate the metamorphic conditions and age of high-pressure and ultrahigh-pressure eclogites from Mali, Togo and NE-Brazil and demonstrate that continental subduction occurred within 20 million years over at least a 2,500-km-long section of the orogen during the Ediacaran. We consider this to be the earliest evidence of large-scale deep-continental subduction and consequent appearance of Himalayan-scale mountains in the geological record. The rise and subsequent erosion of such mountains in the Late Ediacaran is perfectly timed to deliver sediments and nutrients that are thought to have been necessary for the subsequent evolution of sustainable life on Earth.

Timing of deformation in the Sarandí del Yí Shear Zone, Uruguay: Implications for the amalgamation of western Gondwana during the Neoproterozoic Brasiliano‐Pan‐African Orogeny

“…This crustal‐scale structure has been correlated with the easternmost Pampean Belt in the Sierras Pampeanas, mostly based on geophysical data [e.g., Rapela et al ., ; Peri et al ., ]. Nevertheless, the collisional phase of the Pampean Belt was placed at the Lower Cambrian [ Rapela et al ., , ; Siegesmund et al ., ], which is considerably younger than the collision recorded along the Transbrasiliano Lineament [ Ganade de Araujo et al ., , ]. The Sarandí del Yí Shear Zone, in contrast, shows both timing of deformation and kinematics, which are comparable with those recorded along the Transbrasiliano Lineament.…”

Paleomagnetism of the Amazonian Craton and its role in paleocontinents

“…Many authors advocate a final collision between Amazonian-West African Craton and proto-Gondwana at around 650-600 Ma, after closure of the great Goiás-Pharusian ocean separating these cratonic units in earlier times (e.g. Trompette 1994, Cordani et al 2000, Cordani & Teixeira 2007, Cordani et al 2013a, 2013b, Ganade de Araújo et al 2014. In this case, late Neoproterozoic would be characterized by the presence of supercontinent Pannotia (Dalziel 1997), comprising all Gondwana units plus Laurentia, the break-up of Laurentia occurring during the Ediacaran with the formation of the Yapetus Ocean (570 Ma, Cawood et al 2001).…”

“…According to Ganade de Araújo et al (2014), Himalaya-type mountains more than 2500 km long formed along this mega-suture (the Transbrasiliano-Kandy tectonic corridor, Cordani et al 2013b), thus producing eclogitic rocks at about 130 km depth in the lithosphere, whose exhumation occurred at about 615 Ma. Unfortunately, paleomagnetic data between 900 and 600 Ma are rare for all Gondwana cratonic blocks, which make the tectonic processes involving Rodínia break-up and Gondwana formation undefiened.…”

Quimioestratigrafia isotópica (C, O, Sr, Li, Mg) e proveniência sedimentar (U-Pb, Hf, Sm-Nd) do grupo Bambuí no sul da bacia do São Francisco

“…1). Large portions of exposed continental crust are expected to result in a large nutrient influx derived from silicate weathering to marine systems, which is a possible cause for the appearance of complex life forms at the end of Proterozoic Ganade-Araújo et al, 2014). We note however, that this is not a simple picture and the position of the marine basins in relation to the sources may play a significant role on the dissolved influx (Fig.…”

“…Alternated periods of glaciations and greenhouse conditions , atmosphere and ocean oxygenation events Lyons et al, 2014;Sperling et al, 2016), and enhanced nutrient delivery to aquatic systems via silicate chemical weathering Ganade-Araújo et al, 2014) are some of the main hypotheses advocated as the trigger for such life evolution, although the real causes are still debated (e.g. Corsetti et al, 2006;Sperling et al, 2016).…”