Assessing the tectonic significance of a large-scale transcurrent shear zone system: the Pernambuco lineament, northeastern Brazil

Restraining bends in high temperature shear zones: The “Central Cameroon Shear Zone”, Central Africa

“…1), the CCSZ likely forms a large scale fan structure with NS imbricate SZ characterized as synthetic equivalents of the sinistral N50°E-directed shear zones of northern Cameroon (Ngako, 1999; Ngako et al, 2003). This geometry which is similar to the Patos and Pernambuco networks (Vauchez et al, 1995;Neves and Mariano, 1999;Neves et al, 2000Neves et al, , 2004Souza et al, 2006) is compatible with a complex kinematic evolution including superimposition of sinistral and dextral movement parallel to the CCSZ. Likely, this shear zone does not show direct links with its Brasiliano pre-drift counterpart, and the present study has revealed that both shear zones form a complex en-echelon system including one or several intermediate relays (Fig.…”

“…The Central Cameroon Shear Zone (Fig. 1) represents a Pan-African post-collisional ductile fault (Ngako et al, 1991(Ngako et al, , 2003Toteu et al, 2004), and a trans-continental structure marked by bends, parallel or en-echelon relays actually most documented in the NE Brazil (Corsini et al, 1996;Neves and Mariano, 1999;Neves et al, 2000). In this paper, we provide a detailed structural and kinematic study of a Pan-African deep-seated bend and discuss possible geometric links with the Brasiliano potential counterpart.…”

“…1a) in pre-Mesozoic reconstructions (Caby, 1989;Souza et al, 2006). Indeed, Neves and Mariano (1999) demonstrated that the Pernambuco lineament, traditionally proposed to continue into West Africa as the Sanaga or Adamawa faults, is not a trans-continental structure, its tectonic role during the Brasiliano event being secondary.…”

Plates Amalgamation and Plate Destruction, the Western Gondwana History

“…It defines a fan-geometry in central Cameroon, due to its interaction with N40°E directed shear zone system (Ngako et al, 2003). Most works in Cameroon and NE Brazil define the CCSZ and correlative extensions as a dextral shear zone (Ngako et al, 1991;Neves & Mariano, 1999;Njanko et al, 2006;Njonfang et al, 2006;Nzenti et al, 2006). However, recent works in Cameroon have also reported the occurrence of sinistral shear sense indicators associated to the same movement direction as that revealed by the dextral shear markers (Ngako et al, 2003;Njonfang et al, 2006), suggesting a more complex kinematic evolution of the CCSZ.…”

“…The Patos and N-S branches are interpreted as forming a transpressive dextral shear zone with duplexes (Corsini et al, 1996), whereas the Pernambuco SZ represents a major structural boundary between the N-S Cearà-type and E-W Sergipano belts. Tentative correlation of NE-Brazil with its African counterpart (Caby, 1989;Trompette, 1994) shows a good structural fit between the Cearà-type and the Western Nigeria schist belts (Isseyin and Ife), in the one hand, and between the Sergipano and the Yaoundé-Oubanguide Groups, in the other hand; the Patos and Central Cameroon SZ are recognized as structural equivalents (Neves & Mariano, 1999), whereas the Cearà-type SZ are correlated with the trans-Saharan SZ (Caby, 1989). In Brazil, these shear zones are associated to early and latetectonic transcurrent plutons which ages are bracketed between 600-580 Ma, and 575-565 Ma, respectively (Neves et al, 2004;Souza et al, 2006); both age groups may be correlated with the sinistral and dextral shear evolutions in the Cameroon domain.…”