Organic-rich, fine-grained contourites in an epicontinental basin: The Upper Jurassic-Lower Cretaceous Vaca Muerta Formation, Argentina

Over the last few years, recognition and characterization of sedimentary processes in fine-grained successions is receiving considerable attention part due to increased importance unconventional reservoirs. Recent sedimentologic analyses these have revealed abundant traction transport structures that suggest bottom current activity different origins. The present study constitutes a detailed analysis Upper Jurassic-Lower Cretaceous Vaca Muerta Formation (Neuquén Basin, Argentina), which comprises organic-rich, subaqueous clinoform deposits. Locally, intervals showing such as parallel lamination, ripple cross-lamination cross-bedding, displaying high bioturbation, occur. These can be differentiated into three facies associations, namely crinoidal mixed calcareous mudstone, mudstone interbedded with mudstone. associations were deposited by contour currents semi-permanent activity, low sediment concentration, generating long-term oxygen supply seafloor. some display an increasing decreasing bioturbation intensity pattern may similar origin bi-gradational sequence contourites. supports idea are associated levels oxygenation, controls degree preservation structures, consequently possibility delineate successions. occurred relatively shallow water, probably weakened estuarine or anti-estuarine, basin-wide circulation system intensified enhanced action dense water cascading during arid cool climate periods. • Contourite deposits analyzed from cores five wells. show bioturbated, laminated rippled crinoidal, Contour semi-permanent, showed generated oxygenation. was periods vigorous shelf waters.