Sedimentology and architecture of early post-rift submarine deposits: Los Molles Formation, Neuquén Basin, Argentina

PRIVAT, A.; HODGSON, D.M.; JACKSON, C.A-L.; SCHWARZ, E.; PEAKALL, J.

Congreso; 2016 AAPG/SEG International Convention and Exhibition; 2016

AAPG/SEG

The sedimentary architecture of submarine lobe dominated successions in early postrift settings are poorly understood despite commonly being proven hydrocarbon reservoir systems, in part because these types of systems are rarely exposed. Exhumed early postrift deposits in the Neuquén Basin, Argentina, have been investigated in the Jurassic Los Molles Formation, to help understand and predict the subseismic distribution of facies around inherited synrift structures. Two distinct depocenters, La Jardinera and Come Yeguas, are located between NWSE trending extensional synrift footwall highs. The well exposed submarine lobedominated successions have allowed sedimentological and architectural changes in the Los Molles Formation to be constrained by use of correlation panels constructed along a 12 km strike section in La Jardinera and a 2.5 km cross strike section towards synrift faults in Come Yeguas. The early postrift deepwater stratigraphy is characterized by the onlap and pinchout of sandbodies, which in combination with hardground development on footwall highs indicates that deposition occurred across faultblock highs. The basin physiography during deepwater deposition was, therefore, demonstrable conditioned by inherited synrift structures that influenced the timing and location of bypass, erosion and deposition of sand-rich sediment gravity flows. The infill architecture of the two depocenters record different stratigraphic architectures and stratal patterns of sand-rich strata, inferred to be the result of the contrasting responses of marine clastic sedimentation to the inherited syn-rift topography, differential subsidence, sealevel variations and sediment supply. This study provides criteria to decipher relationships between the organization of lobe deposits and inherited syn-rift structures that can be integrated to improve the prediction of reservoir bodies in underexplored early post-rift successions.