Abstract
The thermal evolution of the hydrocarbon exhumated kitchen of the Rio Mayer Formation (Lower Cretaceous) in the Austral-Magallanes basin, was characterized in two profiles outcropping in the Southern Patagonian Andes. This study presents an integration of fluid inclusions, organic petrology, geochemistry, and apatite fission-track data incorporated into a one-dimensional (1D) basin and petroleum system modeling, to evaluate the timing of hydrocarbon generation and expulsion processes. In Ea. La Federica (internal fold-thrust belt domain), the lower organic-rich interval of Rio Mayer Formation is at present-day conditions in oil window, with development of natural fractures filled with fibrous calcite crystals. In Ea. Cristina, the unit is in dry gas window (basement domain), with natural fractures filled with granular calcite and quartz. The kitchens began the generation and expulsion processes from the west (Lower Cretaceous) to east (Upper Cretaceous - Eocene), i.e., from basement to internal and external fold-thrust belt domains. The advance of the orogenic wedge deactivated and exhumated those kitchens from west to east as well. The western kitchen was deactivated during the Late Cretaceous, while eastern kitchen, during the Eocene. These successive compressional pulses conditioned the eastward migration of the hydrocarbon generation front and would have favored the charge of reservoirs located in the westward (foreland region). The results of this study emphasize the importance to consider the temporal source kitchens activation related to Andean deformation, in order to a better comprehension of basin-scale controls related to source rock evolution and petroleum system development.
Published Version
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