A tectonostratigraphic synthesis of the Sub-Andean basins: implications for the geotectonic segmentation of the Andean Belt

Abstract

The tectonic, structural and depositional history of 19 Sub-Andean foreland and eight southern Caribbean basins has been synthesized and is summarized by regional geohistory charts. These charts recapitulate the subsidence regimes recognized and have been used to evaluate correlations between genetically related stratigraphic sequences. Based on spatial and temporal changes in palaeo-depositional setting, the Sub-Andean region can be subdivided longitudinally into several tectonostratigraphic domains. The differential amount of subsidence between two adjacent tectonostratigraphic provinces or sub-provinces relies on the presence of a transverse zone of structural accommodation. The location of these transfer zones correlates with a number of known and several newly identified zones of intracontinental deformation. Combined with changes in the structural geometry of the Andean Fold and Thrust Belt and the relative dominance of basement fault systems along the length of the Andean foreland, it is suggested that the Andean Belt can be separated into five tectonic domains (which are themselves bounded by transverse, structural accommodation zones). Representing the multiphase reactivation of pre-existing basement fault systems, the influence of these broad zones of transcontinental deformation is most apparent during the Triassic-Jurassic period, suggesting that they were intimately associated with accommodating intraplate stresses during the breakup of the Gondwana Supercontinent.

Mafic monogenetic vents at the Descabezado Grande volcanic field (35.5°S–70.8°W): the northernmost evidence of regional primitive volcanism in the Southern Volcanic Zone of Chile

“…Finally, as a remarkable fact, the NNW-SSE and ENE-WSW trends are broadly concordant with the ancient structures that controlled the Late Triassic-Early Jurassic rift systems (Ramos 2009) that were reactivated during the rifting event associated with the opening of the South Atlantic Ocean in the early Cretaceous (Jacques 2003;Ramos 2009). Furthermore, those structural trends have been observed as major features in the entire South American continent, acting as weakness zones which can be repeatedly reactivated, playing a major role in the tectonostratigraphic evolution of the continent (Jacques 2003).…”

“…Furthermore, those structural trends have been observed as major features in the entire South American continent, acting as weakness zones which can be repeatedly reactivated, playing a major role in the tectonostratigraphic evolution of the continent (Jacques 2003). The deep and penetrative character of such structures would explain their effectiveness in channeling and transporting deep-seated mafic magmas through the crust.…”

Amazonian biodiversity and protected areas: do they meet?

“…Tectonically tranquil areas in the Guayanan and Brazilian shield areas have had ample time for a long and continuous soil-forming process (Irion 1978), whereas in the more active western parts of Amazonia the ages of soils can vary from recent to some millions of years (Räsänen et al 1990(Räsänen et al , 1992Salo and Räsänen 1989;Jacques 2003Jacques , 2004. At least in the west, the soils are also derived from quite distinct parent materials from thoroughly leached quartzitic sands to semimarine or lacustrine clays and sands, as well as volcanoclastic sediments (Räsänen et al 1992(Räsänen et al , 1998Hoorn 1995;Wesselingh 2006).…”

Geomorphic evidence for recent uplift of the Fitzcarrald Arch (Peru): A response to the Nazca Ridge subduction

“…Analysis of Subandean basin geometries and subsidence histories all over South America leads Jacques (2003) to the conclusion that the Subandean basins behave more or less independently. These basins would have been separated by lithospheric fault zones (transfer zones), probably inherited from old structures affecting the overall lithosphere, and crossing the entire South America continent (Jacques, 2003;Carlotto et al, 2007). The transfer zones would correspond to ancient strike slip fault zones and are divided into two groups whose respective orientations are NW-SE and ENE-WSW.…”