Abstract: It has been shown in the accompanying paper that the Sub-Andean foreland can be subdivided longitudinally into a number of tectonostratigraphic domains. To test the hypothesis that changes in palaeo-depositional setting rely on the presence of a series of transverse zones of structural accommodation, data have been digitally compiled from across the South American continent. Spatial and temporal geological relationships have been analysed and evaluated as a means of identifying the position of tectonostratigraphic domain boundaries (structural accommodation zones), and patterns of subsidence and intraplate deformation. The results suggest that individually these structural accommodation zones represent a composite of deep crustal fractures which, on a regional scale, interlink to form a transcontinental belt or zone that can accommodate intraplate deformation during episodes of plate reorganization. Their strong spatial relationship with Mesozoic, intraplate, alkaline igneous activity suggests that they exerted an important control on lithospheric melt siting during Gondwana breakup. These localized zones of high heat flow have important implications for source rock maturity in the interior, Phanerozoic intracratonic basins of South America. On the South Atlantic margin, the majority of these crustal lineaments correlate with failed arms of triple-junction rifts and define the boundaries to tectonostratigraphic domains recognized along the South Atlantic Rift System.

Based on spatial and temporal changes in palaeo-depositional setting, the Sub-Andean region can be subdivided longitudinally into a number of tectonostratigraphic domains (Jacques 2003). The differential amount of subsidence between two adjacent tectonostratigraphic provinces or sub-provinces relies on the presence of a transverse zone of structural accommodation. Two predominant sets of basement lineaments arc recognized: ENE-WSW and NW-SE (Fig. 1). The relative dominance of one set of crustal lineaments over the other changes approximately halfway down the length of the Andes, across a broad transition zone structurally expressed by the Arica Deflection-Bolivian Orocline, with ENE-trending crustal lineaments dominating in the north and NW-trending crustal lineaments dominating in the south. Both sets of lineaments occur as major structural anisotropies throughout the basement rocks of South America, providing zones of weakness, which were repeatedly reactivated and, at least in part, controlled: (1) the geometry of inter- and intracratonic rifting; (2) rates of subsidence and uplift along the Andean depositional axis; (3) the position of basin-bounding and intra-basinal highs or arches; (4) the structural geometry of the Andean Deformation Zone, correlating with changes in deformational style and major deflections; (5) the location of magmatism.

Twelve transverse structural lineaments (accommodation zones) are recognized (see Fig. 2) and, from north to south, are referred to as: the ENE Tumbes-Guayaquil-Tacutu Tectonic Lineament; the ENE Solimoes-Amazonas Megashear (diffuse zone of deformation); the ENE Pisco-Abancay-Fitzcarrald Tectonic Lineament; the ENE Arica-Paraguai-Araguaia Tectonic Lineament; the ENE Michicola Tectonic Lineament; the ENE La Serena-Ribeira Tectonic Lineament; the NW Martin Garcia Tectonic Lineament; the NW Valle Fertil Tectonic Lineament; the NW San Rafael Tectonic Lineament; the NW Gastre-Agulhas Megashear; the NW South Malvinas Tectonic Lineament; the east-west North Scotia Tectonic Lineament.