Unraveling the Underwater Morphological Features of Roncador Bank, Archipelago of San Andres, Providencia and Santa Catalina (Colombian Caribbean)

Abstract

In this study, we present the first detailed description of the morphology of the Roncador Bank deep underwater environments, located in the central sector of the SeaFlower Biosphere Reserve (Archipelago of San Andres, Providencia and Santa Catalina-ASAPSC, Republic of Colombia). The analysis was carried out from multibeam bathymetric information recently acquired by the Oceanographic and Hydrographic Research Center of Colombia (CIOH), and the subsequent creation of a 35 m-resolution digital terrain model, which was the main input for the geomorphological mapping. The results allowed to determine that Roncador Bank corresponds to a seamount of highly irregular contour, reaching a height up to 2,350 m with respect to the surrounding seafloor. The volcanic edifice that makes up the seamount is bounded to the south and east by two escarpments, which are tectonically related with the Southern Roncador and Eastern Roncador faults, respectively. We were able to determine that these faults are currently active and that recently have generated earthquakes of magnitudes up to 6.0, which has important implications for the estimated seismic risk in the ASAPSC. This situation allowed to infer that the volcanic processes that formed the Roncador volcano were controlled by the presence of major faults on the seabed. The steep slope gradients (up to 40 • ) of the escarpments effectively concentrate erosive processes, leading to the development of a dense gully network and extensive slope deposits in the hillsides. Also, we identified debris-avalanche deposits indicating the occurrence of partial collapses of Roncador, which shows that gravity-driven mass transport processes have played an important role in the edifice shaping. These largescale underwater landslide events may have the capacity to generate tsunamis, so it is necessary to carry out specific studies to analyze their tsunamigenic potential. Finally, the mapping and detailed description of Roncador seamount morphological features, such as pinnacles, escarpments, hummocky terrains, ridges, gullies and canyons, reported in this study are key to advance in the basic knowledge on the geology and geomorphology of the ASAPSC, and have direct implications for future specific research on the characterization of deep ecosystems, geohazards, natural resources, and territory planning.

A New Method for the Collection of Marine Geomagnetic Information: Survey Application in the Colombian Caribbean

“…A grid-shaped geometric arrangement was preserved to provide good resolution for a regional geological study. The general direction of geological structures and geoforms has a northeast direction [47,48].…”

“…In Figure 10, it can be seen that this anomaly corresponds to the geomorphology of the Nutibara depression, and that it could be generated by some type of mineral deposition that can be found, associated with ferrous materials, or also with volcanic material with a high iron content compared to its geological environment. On the other hand, magnetic lows are observed north of the Cayos de Alburquerque Island, which would seem to be a contradiction, since its morphology is typical of a seamount, and, therefore, its magnetic response should be high [48,53,54].…”

The Colombian Caribbean Sea: a tropical habitat for the Vulnerable sperm whalePhyseter macrocephalus?

“…The Archipelago of San Andrés, Old Providence and Saint Catherine, designated a Seaflower Biosphere Reserve in 2000, has extensive coral reefs, seagrass beds and mangroves (CORALINA–INVEMAR, 2012), productive ecosystems that could provide prey for sperm whales. In addition, the Archipelago is close to the 2,350 m Roncador seamount (Idárraga-García & León, 2019). This could explain the high probability of occurrence of sperm whales in this area, as in the Azores where seamount complexes are prefered habitat for the sperm whale (Tobeña et al, 2016).…”

Shipwrecks on Roncador Cay, the Caribbean Sea and Their Relationship with Hurricanes, 1492-1920

“…Roncador Cay is 400 m long and 150 m wide with a bank of approximately 15 km long and seven km wide with a unique morphology (Geister and Díaz 2007;Idárraga-García and León 2019;Milliman 1969:13, 14;Nicaragua v. Colombia 2008: 26). The complexity of the region's climate is defined by its tropical location modulated by the Intertropical Convergence Zone (ITCZ) with two seasonal periods determined by precipitation (rainy season-August to November) and northeast trade winds with severe weather events as cold fronts (dry season-December to April).…”