New insights into the stratigraphic and structural evolution of the middle Jurassic S. Neuquén Basin from Detrital Zircon (U‐Th)/(He‐Pb) and Apatite (U‐Th)/He ages

摘要: Previous studies on the Lower‐Middle Jurassic Cuyo Group in southern Neuquen Basin, Argentina, have discussed evidence for pre‐ and syn‐depositional structural inversion during pre‐Andean shortening. While sequence stratigraphic facies framework are well understood, effects of progressive postrift thermal subsidence sediment provenance dispersal, as timing magnitude deformation after deposition, remain poorly constrained. The comprises both reservoir‐quality fluvial to deep‐marine siliciclastic deposits a petroleum source‐rock. Thus, temporal relationship between onset dispersal crucial aspects an improved understanding basin evolution system. This study presents new detrital zircon (U‐Th)/(He‐Pb) double dating from Los Molles Lajas Formations area SW Zapala evaluate influence early rift routing, provenance, palaeogeography, provide chronostratigraphic constraints. youngest concordant (DZ) U‐Pb He ages Lohan Mahuida La Jardinera areas suggest late Middle depositional age. DZ analysis confirms that formations part same shelf margin were sourced Choiyoi basement, Late Triassic Andean magmatic arc pre‐Cuyo strata. (DZHe) additional constraints by recording three discrete cooling events, (1) early‐Late Triassic, (2) early‐Early Jurassic, (3) Middle‐Late documenting tectonically driven exhumation rifting contractional stages prior evolution. Triassic‐Jurassic zircons derived document existence Pangean extensional structures basins source area. Furthermore, abundance rapidly cool DZHe requires rapid Carboniferous basement. All this suggests Huincul ridge region started earlier than previously proposed. Hence, challenges conventional tectonodepositional models advocated sagging primary control deposition. occurrence first‐cycle volcanic (U‐Th)/(He‐ Pb) implies burial never reached depths >4–5 kilometres. Exhumation shallower crustal was spatially partitioned Cenozoic shortening constrained AHe ages.