DETACHMENT LEVELS OF COLOMBIAN CARIBBEAN MUD VOLCANOES

Abstract

Regional analysis of mud volcanoes shows the regional extension of these processes in Northern Colombia. Mud volcanoes are active systems with the characteristics of the underlying sedimentary sequences on the surface, as well as the presence of hydrocarbons. These provide information about the oil systems and the characterization of new migration paths. New data acquired during field geology studies, along with the evaluation of acquired aerial images by dron, allowed observation of variations in terms of morphology and neotectonic process, being distinctive among mud volcanoes formed on different structural domains. Mud volcanoes formed in basement areas without thrust faults (Hangingwall realm of the San Jacinto Fault) are usually circular, connected to the basement by regional faults. Other mud volcanoes formed in older and younger deformed belts (Footwall realm of the Sinú Fault and Footwall realm of the San Jacinto Fault respectively) tend to have ellipsoidal shapes, with drainage patterns that suggest local stress fields associated with regional strike-slip movements of major faults. The analysis of U/Pb ages in detrital zircons extracted from mud volcanoes and outcropping sedimentary sequences in the Colombian Caribbean, together with the analysis of foraminifera and palynomorphs, suggest different levels of detachment. Clay mineralogy and geochemistry indicate that mud volcanoes formed in the backstop and the Northern part of the San Jacinto deformed belt have sludge material from sedimentary sequences, with contribution from continental basement rocks, while the mud volcanoes in the central and Southern parts of the studied area tend to show sediments from deepest stratigraphic levels, derived from less evolved magmatic sources (dioritic basements). Gas and water analyses from studied mud volcanoes suggest that the old deformed belt, Paleocene accretionary wedge, and backstop areas, have evidence of thermogenic oil systems, while in the younger deformed belt domain, the tendency is to suggest microbial processes.