Heterogeneous deformation in the configuration of Neogene Patagonian foreland basins: Influence in stratigraphic records

Abstract

The tectonic uplift of orographic barriers determines significant climaticchanges that could be recorded in sedimentary basins. A particular scenario arisesin orogenic systems where basement structures play a significant role in thefragmentation of the retroarc region, generating the compartmentalization of theforeland system into isolated basins. In these systems, the heterogeneousdeformation has a key role in the stratigraphic patterns. The retroarc of the NorthPatagonian Andes provides an exemplary setting for examining these interactions. AMiocene climate change related to Andean uplift was recorded in intermontanebasins, along with numerous internal structures influencing sedimentation. Thesestructures have been broadly defined as reverse faults linked to a contractionalregime. However, the distribution and characteristics of deformation along theretroarc remain unclear. In this study, we integrate geometric and kinematicanalyses of the border and internal structures defining Neogene basins within ablock that fragmented the foreland in the southern Central Andes, specifically theSañicó Massif. The results reveal heterogeneous patterns involving the interactionof contractional and strike-slip components within a transpressional regime,progressing through the reactivation of pre-existing faults and the generation ofnew ones. The current structural configuration of the Patagonian Broken Forelanddoes not follow a contractional deformation pattern, emphasizing the need fordetailed studies to explain how contractional and strike-slip structures interact,generating uplift of orographic barriers, creating accommodation spaces andinterconnecting depocenters.