Preliminary Magnetostratigraphy and Rock Magnetic Analysis of the Vaca Muerta Formation (Upper Jurassic-Lower Cretaceous) in the Puerta Curaco Section, Argentina

A systematic paleomagnetic study was carried out in the Vaca Muerta Formation, a carbonate- ramp system cropping out in the Neuquén basin, west-central Argentina. The Vaca Muerta Formation is one of the most important unconventional hydrocarbon reservoirs in the world and its exhaustive study has become a relevant target in Argentina. In the Puerta Curaco section, this unit is c. 360 m – thick bearing ammonites that indicate Upper Jurassic – Lower Cretaceous ages. Here, paleomagnetic sites were sampled from which nearly 500 specimens were collected and processed. The primary origin of the magnetization was proved through paleomagnetic field tests. As a result, a preliminary magnetostratigraphic scale was constructed dated with ammonites of the Andean Realm, and then correlated to the most recent International Geomagnetic Polarity Time Scale. The resultant magnetostratigraphic scale proved to be consistent with other studies, and allowed the refinement of the temporal framework of the lower part of the Vaca Muerta Formation. Simultaneously, in order to determine the main magnetic carriers of the magnetic remanence several rock magnetism studies
were carried out such as isothermal remanent magnetization (IRM) acquisition curves, thermomagnetic
curves and K vs. field curves that were complemented with observations of magnetic minerals under reflected light and scanning electron microscopy.
Keywords: Vaca Muerta Formation, magnetostratigraphy, magnetic mineralogy, Neuquén basin