STRUCTURAL GEOLOGY AND STRATIGRAPHY OF THE MAJAYURA AREA, GUAJIRA (COLOMBIA)

Abstract

There were migrated in depth three time pre-stack seismic lines of the Majayura-72 program in order to improve coherence and definition of reflectors associated to the Cretaceous and Neogene formations of the Majayura´s area, Lower Guajira basin. Seismic sections were tied with synthetic seismograms, cores and records of the Los Manantiales–1, Maicao–1, Guaitapa–1 y Saure–1 wells, for making sequential interpretation in order to define geologic units and paleo-environments in this area of the basin Cycles of high and low frequency, associated to advance and retreat of the base line, suggest at least two main sequences. The Cretaceous sequence, with three sub-sequences: a lower sub-sequence, corresponding to a continental environment; a middle sequence related with an extern to bathyal shelf. And an upper sequence associated with a medium to extern shelf and bounded in the top by discordance in the Neogene base. Into the Neogene sequence was interpreted a first cycle linked with a rise of the ration accommodation – supplies (A/S) that represents a transgressive sequence (Upper Miocene), and it is correlated with the Jimol formation. Into the Pliocene sequence (Castilletes formation) were defined two subsequences that represent a decrease of the A/S ratio, corresponding to regressive sequences with strong eustatic changes.