Geodynamic context for the deposition of coarse‐grained deep‐water axial channel systems in the P atagonian A ndes

• Published in: Basin research 2014-12, Vol.26 (6), p.726-745
• Main Authors: Ghiglione, M. C., Likerman, J., Barberón, V., Beatriz Giambiagi, L., Aguirre‐Urreta, B., Suarez, F.
• Format: Article
• Language: English
• ISSN: 0950-091X; 1365-2117
• DOI: 10.1111/bre.12061

We present field and seismic evidence for the existence of C oniacian– C ampanian syntectonic angular unconformities within basal foreland basin sequences of the A ustral or M agallanes B asin, with implications for the understanding of deformation and sedimentation in the southern P atagonian A ndes. The studied sequences belong to the mainly turbiditic U pper C retaceous C erro T oro F ormation that includes a world‐class example of conglomerate‐filled deep‐water channel bodies deposited in an axial foredeep depocentre. We present multiple evidence of syntectonic deposition showing that the present internal domain of the fold‐thrust belt was an active C oniacian– C ampanian wedge‐top depozone where deposition of turbidites and conglomerate channels of C erro T oro took place. Cretaceous synsedimentary deformation was dominated by positive inversion of Jurassic extensional structures that produced elongated axial submarine trenches separated by structural highs controlling the development and distribution of axial channels. The position of C oniacian‐ C ampanian unconformities indicates a ca . 50–80 km advance of the orogenic front throughout the internal domain, implying that L ate C retaceous deformation was more significant in terms of widening the orogenic wedge than all subsequent Andean deformation stages. This south P atagonian orogenic event can be related to compressional stresses generated by the combination of both the collision of the western margin of R ocas V erdes B asin during its closure, and A tlantic ridge push forces due to its accelerated opening, during a global‐scale plate reorganization event.