The influence of intraplate structural accommodation zones on delineating petroleum provinces of the Sub-Andean foreland Basins

摘要

The Sub-Andean foreland regionis summarized in a series of palaeogeographical maps.Various time-slices show imrotant basin-forming processes and the extent and evolution of principal depositional elements.Based on spatial and temporal changes in palaeodepositonal setting,the Sub-Andean region can be subdivided longitudinally into a number of tectonostratigraphic domains.The differential amount of subsdience between two adjacent tectonstratigraphic provinces or sub-provinces have bene taken up across,compelx,broad,transverse,transcontinental accommodation zones,which probably represetn the multiphase reactivation of pre-existingfault systems in the underlying basement.Two predominant sets of basement lineaments are recognized:ENE-WSW and NW-SE.Both sets of lineaments occur as major structurla aniostropies throughout the basement rocks of South America,Providing zones of weakness,which were repeatedly reactivated and,at least in part,controleld:(a) the geometry of inter- and intra-cratonic rifting;(b) rates of subsidence and uplift along the Andean depositional axis;(c) the positionof basin-bounding an dintra-basinal highs/arches;(d) the structural geometry fo the Andean Defomraiton Zone,correlating withchanges in deformational style and major deflections;and (e) the locatonof majgmatism.Based primarilyt on source rock age,it is suggested that these transverse,structural accommodation zones had a profound effect on source rock distributionand hydrocarbon occurrence;subdividing the Sub-Andean region into five petroleum provinces/megasystems;a 'Northern'Late Cretaceous (La Luna Formation and equivalents);a 'Western'Late Palaeozoic-Early Mesozoic (Permian and Upper Triassic to Lower Jurassic source rocks);a 'Central'Palaeozoic(Late Devaonian and Silurian);an 'Eastern'Tertiary;and a 'Southern'Mesozoic.