Geological Evaluation Of La Luna Formation At The Matanza Area (West Santander Massif, Colombia)

This study comprised the sedimentological, paleontological and geochemical survey of the La Luna Formation, using as a reference one section in the west flank of the Santander Massif (Matanza, Colombia).The 42-meter length section comprises an alternance of interstratified mudstones, wackestones, chert, phosphorite and bentonite levels. Fossil content is defined by rest of ammonoids, inoceramids, turritellid gastropods, fish remains and planktonic foraminifers, suggesting all a Coniacian-Santonian age. The facial analysis, the fossil content and preliminary petrographic/geochemical analysis also suggest an outer shelf setting and low oxygenation conditions in the bottom sediments.In general, our results agree with previous interpretations of La Luna Formation, suggesting a closer relation with the Upper Cretaceous succession of the Middle Magdalena (upper "Galembo Member"). However, only detailed stratigraphical studies in this part of the Santander Massif, will allow a better understanding of its geological evolution during the Late Cretaceous.