Subsurface basement, structure, stratigraphy, and timing of regional tectonic events affecting the Guajira margin of northern Colombia

Abstract

We combine previous data from Mesozoic-Cenozoic outcrops in the Guajira Peninsula of northern Colombia with regional gravity, bathymetric, and seismic interpretations to demonstrate the existence of a 280-km-long western extension of the Great Arc of the Caribbean (GAC) along the continental margin of Colombia. Seismic data reveal an 80- to 100-km-wide domal-shaped basement high which exhibits internal chaotic seismic facies. This elongate and domal-shaped structure extends 1800 km from the Aves Ridge in the Caribbean Sea to the study area in offshore Colombia. The western extension of the GAC in Colombia and western Venezuela is buried by 700 to 3000 m of continental margin sedimentary rocks as a result of the GAC colliding earlier with the Colombian margin (Cretaceous-early Paleogene collision) than its subaerially-exposed eastern extension along the Leeward Antilles Ridge (late Paleogene-Neogene). Our compilation of geologic information from the entire GAC shows that GAC magmatism occurred from 128 to 74 Ma with magmatism ages progressively younger towards the east. Six Upper Eocene to Recent marine seismic sequences overlying the domal basement high of the GAC have been mapped by our analysis of 2400 km of seismic lines and 12 well log data. Based on subsurface mapping correlated with well log information and onland geology in the Guajira Peninsula, these six sequences record four major deformational events: 1) late Eocene rifting in an east-west direction produced half-grabens in the northern part of the area; 2) Oligocene transtension in the southern part of the area expressed by right-lateral Oligocene strike-slip faulting and extensional basin formation; 3) early-middle Miocene transtension; and 4) late Miocene-early Pliocene Andean uplift accompanied by rapid erosion and clastic infilling of offshore basins by the Magdalena delta and deep-sea fan. The significance of this basin framework is discussed for known and inferred hydrocarbon systems.

Basin Evolution and Shale Tectonics on an Obliquely Convergent Margin: The Bahia Basin, Offshore Colombian Caribbean

“…A slight rotation of the Santa Marta Massif due to the partitioning of deformation would mean that faults such as the Cuisa and Oca faults may have originally been oriented in a more NE‐SW trend, allowing them to accommodate strike‐slip displacement (see change in Figures a and b). As a result, pull‐apart basins started to form along the margin since late Eocene times initially in the north (i.e., northern Guajira and Leeward Antilles; Gorney et al, ; Macellari, ), followed by the pull‐apart basin formed along the Cuisa Fault in Oligocene times (Gomez, ; Vence, ). This may suggest a diachroneity in basin formation from north to south (Figure b).…”

“…Further east, a NW‐SE trending fault connected Fault A with the Oca Fault and formed the eastern end of the basin (i.e., Fault A'). These NW‐SE trending faults formed at the rear of accretionary prism to transfer the right‐lateral displacement to the Cuisa and Oca faults, contributing to the break‐up and lateral displacement along the margin and controlling the deposition of marine sequences in the offshore basins (“Baja Guajira” in Escalante, , and “Ranchería” in Vence, ) and estuary systems in the Palomino basin (Piraquive et al, ; Figure c).…”

“…However, there is a gap, at least in its near‐surface continuity, in the area of the Magdalena Fan, which is used by Escalona and Mann () to separate the SFB and SJFB to the SW from the SCDB sensu stricto and Leeward Antilles to the NE. There are very few studies on the eastern side of the Magdalena Fan (i.e., western end of the SCDB sensu stricto) and the few that exist focus on the fore‐arc basins and the shelf area of the Nazareth and Jarara Basins (Escalante, ; Gomez, ; “Ranchería Basin” in Vence, ), and there are only a few published 2‐D seismic lines that image the accretionary prism.…”

Estratigrafía secuencial de la Sub-cuenca de la Baja Guajira

“…La Cuenca de la Guajira ha sufrido varios eventos de deformación importantes; el primero correspondiente a un proceso de apertura "Rifting" en el Eoceno tardío que generó medio grabens "Half-grabens" en el norte de la región, seguido por transtensión en el Oligoceno que produjo cuencas extensionales; transtensión durante el Mioceno temprano y medio, y un último evento asociado al levantamiento de los Andes durante el Mioceno tardío -Plioceno temprano, paralelo al relleno de las cuencas sedimentarias. [12].…”

“…Los esfuerzos tectónicos en el sector de la Guajira están por lo general localizados en las zonas aledañas a tales fallas y se relacionan con los movimientos transcurrentes de las mismas. [12].…”