STRUCTURAL AND SEISMOSTRATIGRAPHIC EVIDENCE IN THE NORTH OF THE MAGDALENA SHELF, WESTERN MARGIN OF BAJA CALIFORNIA BASED ON SEISMIC REFLECTION

The theoretical and practical techniques that are currently used for the processing and interpretation of seismic marine data 2D multichannel, are used to characterize a sector of the Magdalena Shelf, located on the western margin of Baja California Sur, Mexico. The study area is located within the geographical position 24º41’ to 25º30’ north latitude and 113º0’ a 112º12’ of west longitude. The seismic marine data used were obtained in the early 80's by Petroleos Mexicanos (PEMEX). The seismic data were submitted to a conventional processing sequence, the processing sequences consisted of three stages: Pre-stack, Stack and Post-stack. The objective of treatment of seismic data was isolate reflections records from other seismic events that will cause noise in the signal of interest, obtaining seismic images with less noise, of which were interpreted ten seismic reflectors with high contrast of acoustic impedance, one regional fault (San Lázaro Fault; FSL) and some extensional normal faults of small size. Of the interpretation one structural model was obtained, which contains two asymmetrical depocentres: Tosco-Abreojos and San Lazaro basin and are controlled by FSL and Tosco-Abreojos fault (FTA). Be inferred that the dip and deformation of the basins are controlled by the these faults, the tectonic development is complex, the efforts were initially compressional but some transcurrent faults and faulted blocks at present indicate that these structures are formed by transtensional efforts, that developed after the cessation of subduction. The San Lazaro depocentre basin arrives until the 4s in double time (~4km of depth), and it is controlled by the FSL that is regional listric normal fault with a ~40º of dip. The reflectors observed by Brothers, et al. (2012) y Salazar (2014) to the south of the study area, also observed in this work, however, there are new reflectors to the NW, these fill the spaces of both depocentres basins, having in total of 8 main sedimentary packages and high structural (subduction complex) extending to the SE-NW direction along the Magdalena platform. This may be related to the high structural Lagunitas in the central part of the peninsula of Baja California.