Examinando por Materia "Caribbean Sea"
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Ítem Atlantic Multidecadal Oscillation (AMO) forcing on the late Holocene Cauca paleolake dynamics, northern Andes of Colombia(Copernicus GmbH, 2015-01-01) Martínez J.I.; Obrochta S.; Yokoyama Y.; Battarbee R.W.; Universidad EAFIT. Departamento de Geología; Ciencias del MarThe Atlantic Multidecadal Oscillation (AMO), is a major driving climate mechanism, in the eastern Caribbean Sea and the South Atlantic Ocean in relation to the dynamics of the South American Monsoon System (SAMS) for the late Holocene. Here we document the AMO signal in the San Nicolás-1 core of the Cauca paleolake (Santa Fé-Sopetrán Basin) in the northern Andes. Wavelet spectrum analysis of the gray scale of the San Nicolás-1 core provides evidence for a 70 yr AMO periodicity for the 3750 to 350 yr BP time interval, whose pattern is analogous to the one documented for the Cariaco Basin. This supports a possible correlation between enhanced precipitation and ENSO variability with a positive AMO phase during the 2000 to 1500 yr BP interval, and its forcing role on the Cauca ria lake deposits, which led to increased precipitation and to the transition from a igapo (black water) to a varzea (white water) environment ca. 3000 yr BP. © Author(s) 2015.Ítem Fluvial fluxes from the Magdalena River into Cartagena Bay, Caribbean Colombia: Trends, future scenarios, and connections with upstream human impacts(ELSEVIER SCIENCE BV, 2018-02-01) Restrepo, J.D.; Escobar, R.; Tosic, M.; Universidad EAFIT. Departamento de Geología; Ciencias del MarFluxes of continental runoff and sediments as well as downstream deposition of eroded soils have severely altered the structure and function of fluvial and deltaic-estuarine ecosystems. The Magdalena River, the main contributor of continental fluxes into the Caribbean Sea, delivers important amounts of water and sediments into Cartagena Bay, a major estuarine system in northern Colombia. Until now, trends in fluvial fluxes into the bay, as well as the relationship between these tendencies in fluvial inputs and associated upstream changes in the Magdalena catchment, have not been studied. Here we explore the interannual trends of water discharge and sediment load flowing from the Magdalena River-Canal del Dique system into Cartagena Bay during the last three decades, forecast future scenarios of fluxes into the bay, and discuss possible connections between observed trends in fluvial inputs and trends in human intervention in the Magdalena River basin. Significant upward trends in annual runoff and sediment load during the mid-1980s, 1990s, and post-2000 are observed in the Magdalena and in the Canal del Dique flowing into Cartagena Bay. During the last decade, Magdalena streamflow and sediment load experienced increases of 24% and 33%, respectively, compared to the pre-2000 year period. Meanwhile, the Canal del Dique witnessed increases in water discharge and sediment load of 28% and 48%, respectively. During 26 y of monitoring, the Canal del Dique has discharged ~ 177 Mt of sediment to the coastal zone, of which 52 Mt was discharged into Cartagena Bay. Currently, the Canal drains 6.5% and transports 5.1% of the Magdalena water discharge and sediment load. By 2020, water discharge and sediment flux from the Canal del Dique flowing to the coastal zone will witness increments of ~ 164% and 260%, respectively. Consequently, sediment fluxes into Cartagena Bay will witness increments as high as 8.2 Mt y- 1 or 317%. Further analyses of upstream sediment load series for 21 tributary systems of the main Magdalena during the 2005–2010 period reveal that six tributaries, representing 55% of the analyzed Magdalena basin area, have witnessed increasing trends in sediment load, raising the river's sediment load by 44 Mt y- 1. Overall, trends in sediment load of the Magdalena and the Canal del Dique during the last three decades are in close agreement with the observed trends in human induced upstream erosion. The last decade has witnessed even stronger increments in fluvial fluxes to Cartagena Bay. Our results emphasize the importance of the catchment-coast linkage in order to predict future changes of fluvial fluxes into Caribbean estuarine systems. © 2016 Elsevier B.V.Ítem Late Holocene marine terraces of the Cartagena region, southern Caribbean: The product of neotectonism or a former high stand in sea-level?(PERGAMON-ELSEVIER SCIENCE LTD, 2010-03-01) Ignacio Martinez, J.; Yokoyama, Yusuke; Gomez, Andres; Delgado, Adriana; Matsuzaki, Hiroyuki; Rendon, Esteban; Universidad EAFIT. Departamento de Geología; Ciencias del MarThe detailed stratigraphic survey and paleontological study (mollusks, corals, foraminifera and ostracods) of four low-level, ~3 m, marine terrace sections: Punta Canoas, Manzanillo del Mar, Playa de Oro, and Tierra Bomba Island, from the Cartagena region, southern Caribbean, supplemented with 22 radiocarbon dates, reveals that the northern terraces were deposited as parasequences in a clastic depositional system compared to the Tierra Bomba Island succession that was deposited in a carbonate depositional system between ~3600 and ~1700 cal yrs BP. Drier conditions and the southern location of the ITCZ at about 3 ka triggered stronger easterly Trades and more dynamic southwestward sediment drift fed by the Magdalena River mouth, thus promoting the formation of sand spits that ultimately isolated the Cienaga de Tesca coastal lagoon from the Caribbean Sea. Our estimates support the hypothesis that the present position of the terraces is the product of neotectonism rather than a higher 3 ka, sea-level. Upheaval of the terraces varies between ~3.8 mmyr-1 at Punta Canoas and ~2.2 mmyr-1 at Tierra Bomba to ~1.5 mmyr-1 at Manzanillo del Mar and Playa de Oro terraces. Our study corroborates previous contentions on the role of mud diapirism and the dynamics of the Dique Fault as late Holocene upheaval mechanisms. © 2009 Elsevier Ltd. All rights reserved.Ítem Modeling the sediment dynamics in the gulf of Urabá colombian Caribbean sea(Elsevier Ltd, 2018-01-01) Escobar C.A.; Velásquez-Montoya L.; Universidad EAFIT. Departamento de Geología; Ciencias del MarThe potential of the gulf of Urabá to hold a multi-purpose port motivated a sediment dynamics study to describe the seasonal sediment concentration patterns in this tropical region. Challenges addressed in this study include a complex three-dimensional flow pattern in a tropical estuary and the lack of in-situ measurements. To overcome such challenges, this study completed: (i) Measurements of suspended sediment concentrations during two climatic seasons and an extreme event (2010–2011); (ii) Definition of boundary conditions from global databases; (iii) Qualitative analysis of sediment concentrations from satellite imagery; and (iv) integration of the previously mentioned steps to build a process-based 3D sediment transport model. Seasonal patterns of suspended sediment concentrations were identified and corroborated by the agreement between model results, satellite imagery and field measurements. During the calm rainy season, the Atrato River turbid plume extends northward and dominates the sediment dynamics in the gulf. On the other hand, during the dry season and extreme events, bed transport is enhanced and the river's plume and the littoral drift shift southwards. © 2017 Elsevier LtdÍtem Modelo hidrodinámico y de oleaje del mar caribe : DELFT Caribe(Universidad EAFIT, 2019) Posada Jaramillo, Federico; Correa Arango, Iván DaríoA two-dimensional large scale mathematical model is presented, which was later migrated to three dimensions, coupling hydrodynamics and waves in the southern Caribbean Sea, named Delft Caribe. The low spatial and temporal coverage of the oceanographic measurements in the study area and the need to know the waves, currents and tides, and the interaction between them at different points of interest led to the construction of this model. The Delft 3D modeling platform was used, which is extensively validated for multidimensional simulation of flows and transport phenomena. The model considers at its borders tidal forcing, atmospheric factors, discharges of tributaries and waves from the Atlantic Ocean. The model results were validated, statistically and qualitatively, for the dry and wet seasons. The good results of the model allow to carry out different experiments aimed to know the performance of the tool to calculate the following: • Velocities of surface currents. • Changes in directions and heights of waves. • Levels of waves. • Changes in the above mentioned variables due to the passage of cold fronts and hurricanes. It was observed that the waves in the southern Caribbean come parallel to the trade winds (Northeast to Southwest) from the Lesser Antilles, to the Guajira peninsula continuing toward the Central American coast of Honduras and Nicaragua, and simultaneously turning south to the Gulf of Urabá and the coasts of Costa Rica and Panama. The significant heights in the model area increased in the dry season and with the passage of storms, with wave heights of: • 6 m in the zone near Guajira Peninsula- • 3 m in the Urabá Gulf. • 3 m in the San Andrés Archipelago zone. The model simulates, in a coherent manner, the Caribbean Current and Panamá Colombia Gyre. The first comes from the Atlantic entering through the model east border and flows to the Guajira Peninsula, where it turns into the Gulf of Mexico and the second is a gyre flowing from Panama to Colombia, with higher velocities during the wet season when the Caribbean current is less strong.Ítem Paleoceanographic conditions in the western Caribbean Sea for the last 560 kyr as inferred from planktonic foraminifera(ELSEVIER SCIENCE BV, 2007-09-14) Martinez, J. Ignacio; Mora, German; Barrows, Timothy T.; Universidad EAFIT. Departamento de Geología; Ciencias del MarFaunal analyses of planktonic foraminifera and upper-water temperature reconstructions with the modern analog technique are studied and compared to the magnetic susceptibility and gamma ray logs of ODP Core 999A (western Caribbean) for the past 560 kyr in order to explore changes in paleoceanographic conditions in the western Caribbean Sea. Long-term trends in the percentage abundance of planktonic foraminifera in ODP Core 999A suggest two hydrographic scenarios: before and after 480 ka. High percentage abundances of Neogloboquadrina pachyderma and Globorotalia inflata, low abundances of Globorotalia menardii and Globorotalia truncatulinoides, low diversity, and sea-surface temperatures (SST) under 24 °C are typical characteristics occurring from 480 to 560 ka. These characteristics suggest a "shallow" well-oxygenated upper thermocline and the influx of nutrients by either seasonal upwelling plumes and/or eddy-mediated entrainment. The second scenario occurred after 480 ka, and it is characterized by high and fluctuating percentage abundances of Neogloboquadrina dutertrei, G. truncatulinoides, G. menardii, Globigerinita glutinata, Globigerinella siphonifera, and Globigerinoides ruber; a declining trend in diversity; and large SSTs. These characteristics suggest a steady change from conditions characterized by a "shallow" thermocline and chlorophyll maximum to conditions characterized by a "deep" thermocline (mainly during glacial stages) and by more oligotrophic conditions. The influence of the subtropical North Atlantic on the upper thermocline was apparently larger during glacial stages, thus favoring a deepening of the thermocline, an increase in sea-surface salinity, and a dramatic reduction of nutrients in the Guajira upwelling system. During interglacial stages, the influx of nutrients from the Magdalena River is stronger, thus resulting in a deep chlorophyll maximum and a fresher upper ocean. The eddy entrainment of nutrients is the probable mechanism responsible of transport from the Guajira upwelling and Magdalena River plumes into ODP 999A site. © 2007 Elsevier B.V. All rights reserved.