Potential geodynamic relationships between the development of peripheral orogens along the northern margin of Gondwana and the amalgamation of West Gondwana

History of the West African Neoproterozoic Ocean: Key to the geotectonic history of circum-Atlantic Peri-Gondwana (Adrar Souttouf Massif, Moroccan Sahara)

“…With respect to the slightly younger ages indicating metamorphism towards S, the final closure of the West African Neoproterozoic Ocean in the area of the Adrar Souttouf Massiv and its southern extension potentially proceeded diachronously from N to S. This is also consistent to the younger ages given by Villeneuve et al (2010). Accordingly, the Adrar Souttouf Massif is the first area, in which remnants of the proposed oceanic tract between Avalonia (Oued Togba unit) and Meguma (Sebkha Gezmayet unit) on the one side and the West African Craton (Murphy et al, 2013) on the other could be identified.…”

“…6) is in line with the established hypotheses concerning the movements of Meguma and the Avalonia terrane assemblage during the Iapetus and Rheic Ocean evolution (e.g. Nance et al, 2010;Murphy et al, 2011Murphy et al, , 2013. The opening of the Atlantic Ocean separated the North American terranes from the Oued Togba and Sebkha Gezmayet units that stuck at the western margin of the West African Craton.…”

“…Both of the ages are interpreted to represent a major magmatic or tectonic event, respectively. Therefore, the 634 Ma age is interpreted to reflect the main peak of island arc formation due to oceanward subduction Murphy et al, 2013). This age is in accordance to other coeval subduction-related magmatic events along the western margin of the West African Craton Villeneuve and Dallmeyer, 1987;Dallmeyer and Lécorché, 1990;Hefferan et al, 2000;Doblas et al, 2002;Condie, 2003;Lahondère et al, 2005;Gasquet et al, 2008;Caby and Kienast, 2009;El Hadi et al, 2010;Fig.…”

Mapping a hidden terrane boundary in the mantle lithosphere with lamprophyres

“…Given that the radiogenic Sr enrichment is so prevalent in the source of post-Variscan lamprophyres throughout Europe, the likely geological context for this event is the Cadomian Orogeny. This period of accretionary mountain-building at the active margin of Gondwana during the late Neoproterozoic to Cambrian has affected all major pre-Variscan continental blocks in Armorican Europe, which have otherwise disparate older histories 14 , 46 . The more widespread potassic-hydrous metasomatism that overprinted the terrane boundary can most easily be explained as having occurred above a north-dipping slab during Variscan subduction of oceanic lithosphere, although Late Devonian-Early Carboniferous alkaline intra-plate magmatism in the region 47 is not fully discounted here as a contributing cause of the metasomatism.…”

Gondwana collision

“…The contribution by (1) Murphy et al (2013) summarizes the early geodynamic history of peri-Gondwanan terranes (e.g. Avalonia, Carolinia, Cadomia) along the northern margin of Gondwana.…”