Artículos (Ciencias del Mar)

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Stratigraphic mensuration, order and homotaxy
(Wiley-Blackwell, 1998-06-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Palaeoceanography of the last glacial maximum in the eastern Indian Ocean: Planktonic foraminiferal evidence
(ELSEVIER SCIENCE BV, 1999-01-01) Martínez, J.I.; De Deckker, P.; Barrows, T.T.; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Palaeoceanographic conditions in the eastern Indian Ocean for the last ~30 kyr are documented by means of planktonic foraminiferal analyses of 10 gravity cores. Quantitative foraminiferal analysis (%), Q-mode factor analysis, the modern analog technique (MAT) and oxygen-isotope analyses are used. A conspicuous increase during the last glacial maximum (LGM) of foraminiferal fragmentation resulting from a more productive Java upwelling system and/or a more corrosive Antarctic Intermediate Water (AAIW) was found at intermediate water depths (~1000 m). Contrasting Q-mode factors based on foraminifera between today and the LGM suggest changes in the thermocline depth, sea-surface temperature (SST), upwelling, and the strength of both the Australasian Mediterranean Water (AAMW) and the Indian Central Water (ICW). The decrease in the percentage abundance of shallow-dwelling and symbiont-bearing planktonic foraminifera, the increase in percentage of the upwelling-related species Globorotalia cultrata and Neogloboquadrina dutertrei, and factor 3 (dominated by Globorotalia tumida and Globigerinella siphonifera) suggest a stronger Java upwelling system during the LGM. A steeper, steric latitudinal gradient (in the presence of a weak Leeuwin Current), and a geostrophic flow similar to today's is postulated for the LGM, and this must have prevented upwelling offshore Western Australia. Today's AAMW-ICW sharp front was weaker during the LGM when the AAMW was saltier, cooler, and nutrient richer and more similar to the ICW. During the LGM, a more gentle SST latitudinal gradient over the ~16 to ~23°S region contrasts with today's steeper conditions at the AAMW-ICW Front. Also, for the LGM, a nutrient-rich ICW may explain previously documented increases in mass accumulation rates of CaCO3, organic carbon and benthonic foraminifera in a region where the nutricline was deep and within the lower euphotic zone.
Los microfósiles como herramienta de correlación estratigráfica en exploración petrolera
(Fondo Editorial Universidad EAFIT, 1999-01-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
La sucesión paleoambiental del Cretácico de la región de Tequendama y oeste de la sabana de Bogotá, Cordillera Oriental Colombiana.
(Universidad Nacional de Colombia. Facultad de Minas, 1999-03-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Coastal erosion and village relocation: a Colombian case study
(Elsevier, 2000-01-01) Correa-Arango, Ivan D.; Gonzales, Juan Luis; Universidad EAFIT. Departamento de Geología; Ivan D. Correa-Arango (icorrea@eafit.edu.co); Ciencias del Mar
Because of its tectonic setting, the Paci"c coast of Colombia is subject to a variety of geological hazards, including earthquakes, tsunamis and associated phenomena such as regional and local coastal subsidence, #ooding and soil liquefaction. Erosional trends are prevalent along much of the 700 km long, low barrier island's shorelines of the Paci"c littoral and land losses are enhanced by factors such as 30 cm regional sea level rises associated to the occurrence of El Nin8o. Marine erosion is threatening more seashore littoral villages and worsening the already di$cult socioeconomic conditions of most part of the inhabitants. Because of diverse and strong motivations to stay near the sea, the responses of barriers island's inhabitants to marine erosion has consisted in most cases of repetitive in-shore and along-shore directed relocations of villages, rather than de"nitive abandonment of the islands. In the long run, this procedure only has postponed the problem and led to repetitive relocations and economical losses. The recent inland relocation of El Choncho village, on the San Juan River delta, illustrates a di!erent response to marine erosion. Although a new along-shore relocation was physically possible, inhabitants decided to abandon the barrier island and migrate to an interior, ancient beach ridge complex, applying a prudent solution which will be the most appropriate for other threatened villages of the Paci"c littoral. A detailed geomorphologic mapping program must be conducted in order to identify appropriate sites for inland relocation of existing villages on the barriers islands of the Colombian Paci"c coast. ( 2000 Elsevier Science Ltd. All rights reserved.
Coastal erosion and village relocation: A Colombian case study
(ELSEVIER SCI LTD, 2000-01-01) Correa, ID; Gonzalez, JL; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Because of its tectonic setting, the Pacific coast of Colombia is subject to a variety of geological hazards, including earthquakes, tsunamis and associated phenomena such as regional and local coastal subsidence, flooding and soil liquefaction. Erosional trends are prevalent along much of the 700 km long, low barrier island's shorelines of the Pacific littoral and land losses are enhanced by factors such as 30 cm regional sea level rises associated to the occurrence of El Nino. Marine erosion is threatening more seashore littoral villages and worsening the already difficult socioeconomic conditions of most part of the inhabitants. Because of diverse and strong motivations to stay near the sea, the responses of barriers island's inhabitants to marine erosion has consisted in most cases of repetitive in-shore and along-shore directed relocations of villages, rather than definitive abandonment of the islands. In the long run, this procedure only has postponed the problem and led to repetitive relocations and economical losses. The recent inland relocation of El Choncho village, on the San Juan River delta, illustrates a different response to marine erosion. Although a new along-shore relocation was physically possible, inhabitants decided to abandon the barrier island and migrate to an interior, ancient beach ridge complex, applying a prudent solution which will be the most appropriate for other threatened villages of the Pacific littoral. A detailed geomorphologic mapping program must be conducted in order to identify appropriate sites for inland relocation of existing villages on the barriers islands of the Colombian Pacific coast. (C) 2000 Elsevier Science Ltd.Because of its tectonic setting, the Pacific coast of Colombia is subject to a variety of geological hazards, including earthquakes, tsunamis and associated phenomena such as regional and local coastal subsidence, flooding and soil liquefaction. Erosional trends are prevalent along much of the 700 km long, low barrier island's shorelines of the Pacific littoral and land losses are enhanced by factors such as 30 cm regional sea level rises associated to the occurrence of El Nino. Marine erosion is threatening more seashore littoral villages and worsening the already difficult socioeconomic conditions of most part of the inhabitants. Because of diverse and strong motivations to stay near the sea, the responses of barriers island's inhabitants to marine erosion has consisted in most cases of repetitive in-shore and along-shore directed relocations of villages, rather than definitive abandonment of the islands. In the long run, this procedure only has postponed the problem and led to repetitive relocations and economical losses. The recent inland relocation of El Choncho village, on the San Juan River delta, illustrates a different response to marine erosion. Although a new along-shore relocation was physically possible, inhabitants decided to abandon the barrier island and migrate to an interior, ancient beach ridge complex, applying a prudent solution which will be the most appropriate for other threatened villages of the Pacific littoral. A detailed geomorphologic mapping program must be conducted in order to identify appropriate sites for inland relocation of existing villages on the barriers islands of the Colombian Pacific coast.
Frequent non-storm washover of barrier islands, Pacific coast of Colombia
(COASTAL EDUCATION & RESEARCH FOUNDATION, 2000-01-01) Morton, RA; Gonzalez, JL; Lopez, GI; Correa, ID; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Barrier islands of the Pacific coast of Colombia repeatedly experience severe washover even when breaking waves in the eastern Pacific are low and onshore winds are calm. On the barrier island of El Choncho, recent non-storm washover events have breached a new inlet, caused rapid beach retreat, destroyed a shoreline protection structure, and flooded a small village of indigenous people so frequently that it had to be relocated. Barrier washover may be augmented by lowered land elevations associated with earthquake-induced subsidence or long-term beach retreat, but temporally it is most closely associated with a 20 to 30 cm regional increase in sea level caused by El Nino. The contradiction of a tranquil tropical island scene simultaneously disturbed by hostile turbulent washover may be unique at present, but it exemplifies how coastal plains throughout the world would be affected if sea level were to rise rapidly as a result of global warming.
Reconstrucción de las presiones parciales de CO2 y nitrato en el Pacifico Oriental para los últimos 150.000 años
(UNIV NAC COLOMBIA, FAC NAC MINAS, 2000-01-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Sea-surface temperatures of the southwest Pacific Ocean during the Last Glacial Maximum
(AMER GEOPHYSICAL UNION, 2000-02-01) Barrows, TT; Juggins, S; De Deckker, P; Thiede, J; Martinez, JI; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
The southwest Pacific Ocean covers a broad range of surface-water conditions ranging from warm, salty water in the subtropical East Australian Current to fresher, cold water in the Circumpolar Current. Using a new database of planktonic foraminifera assemblages (AUSMAT-F2), we demonstrate that the modern analog technique can be used to accurately reconstruct the magnitude of sea-surfacetemperature (SST) in this region. We apply this technique to data from 29 deep-sea cores along a meridional transect of the southwest Pacific Ocean to estimate the magnitude of SST cooling during the Last Glacial Maximum. We find minimal cooling in the tropics (0°-2°C), moderate cooling in the subtropical midlatitudes (2°-6°C), and maximum cooling to the southeast of New Zealand (6°-10°C). The magnitude of cooling at the sea surface from the tropics to the temperate latitudes is found to generally be less than cooling at the surface of adjacent land masses. Copyright 2000 by the American Geophysical Union.
Productividad y oxigenación en la Cuenca de Panamá, Pacífico Colombiano, durante el Pleistoceno tardío-Holoceno: el registro de los Foraminíferos Bentónicos
(Universidad Nacional de Colombia. Facultad de Minas, 2001-01-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Recent planktonic foraminifera from deep-sea sediments from the eastern equatorial Pacific: proxies of the Equatorial Front in the Late Quaternary
(Instituto de Ivestigaciones Marinas y Costeras-INVEMAR, 2001-01-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Late Holocene evidence of coseismic subsidence on the San Juan delta, Pacific coast of Colombia
(COASTAL EDUCATION & RESEARCH FOUNDATION, 2001-01-01) Gonzalez, JL; Correa, ID; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
The San Juan delta of Colombia formed under a complex physical setting. Among the unusual factors that controlled the delta formation are: its location in an area with one of the highest precipitation rate anywhere in the world, highly variable river discharge and high sea levels of short duration, both associated with El Niño-La Niña climatic disturbance, and high mesotidal range combined with a medium to low wave energy. Of all the aspects that make the physical setting complex, the high seismicity produced by the subduction of the Nazca plate under the South American plate, has perhaps, been the most important controlling factor in the Late Holocene development of the delta. Coring on its SW island retrieved soils buried, 1.2-1.5 m by intertidal deposits; the sharp contact between the soils and the mantling deposits, implies large sudden submergence, which is most simply explained as being coseismic, associated with the high seismicity of the area. Timing of the earthquake that caused subsidence, is placed around 500 years BP. Evidence from recent earthquakes along the South central Pacific coast of Colombia indicates that - subsidence > 1 m requires a M 7.9 or greater earthquake.
La Niña-like conditions in the eastern equatorial Pacific and a stronger Choco jet in the northern Andes during the last glaciation
(American Geophysical Union (AGU), 2002-12-30) Martínez, Ignacio; Keigwin, Lloyd; Barrows T., Timothy; Yokoyama, Yusuke; Southon, John; Universidad EAFIT. Departamento de Geología; Martínez, Ignacio (jimartin@eafit.edu.co); Ciencias del Mar
Six deep sea cores from the eastern equatorial Pacific (EEP) were analyzed for planktonic foraminifera and stable isotopes in order to reconstruct sea surface temperatures (SST) for the last 40 ka. South of the Equatorial Front the abundance of Globorotalia inflata increased, and SST decreased by >5°C (core ODP846B), creating a stronger SST meridional gradient and advection of the Peru Current than present for the ∼16–35 ka interval. A sharper SST meridional gradient forced stronger Choco jet events and a moisture increase in western Colombia, which supplied, through the San Juan River and the south-flowing equatorial and the Peru-Chile countercurrents, abundant hemipelagic quartz over the northern Peru basin (core TR163-31B). The Choco jet, and its associated mesoscale convective cells, provoked an increase in snow precipitation over the Central Cordillera of Colombia and the advance of the Murillo glacier. In synchrony with the intensified Choco jet events, the “dry island” effect over the Eastern Cordillera of Colombia intensified, and the level of Fuquene Lake dropped.
Morphodynamics of a high discharge tropical delta, San Juan River, Pacific coast of Colombia
(ELSEVIER SCIENCE BV, 2002-12-30) Restrepo, JD; Kjerfve, B; Correa, ID; Gonzalez, J; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
The San Juan River has one of the most extensive and best developed deltas on the Pacific coast of South America, measuring 800 km2. The river drainage basin measures 16465 km2 and is located in one of the areas with the highest precipitation in the western hemisphere. The annual rainfall varies from 7000 to 11 000 mm, and as a result the San Juan River has the highest water discharge (2550 m3 s-1), sediment load (16×106 t yr-1), and basin-wide sediment yield (1150 t km-2 yr-1) on the west coast of South America. The San Juan delta growth began approximately 5000 years BP. The structure of the delta is determined by the interactions between fluvial deposition and the effect of 1.7-m significant swells, mostly from the SW, and strong tidal currents. Analysis of delta progradation indicates that during 1848-1992 the morphology of the delta was characterized by beach ridge accretion, spit growth, narrowing of inlets, and a general advance of the delta shoreline. During the past decade processes such as rapid erosion of the delta shore, narrowing of barrier islands, and breaching of a new inlet, are the result of a long-term relative sea-level rise of 2.6 mm yr-1 due to tectonically induced subsidence coupled with a eustatic rise of sea-level. The delta also experiences strong oceanographic manifestations associated with the El Niño-La Niña cycle, causing regional sea-level elevation of 20-30 cm during El Niño years. Recent coastal subsidence in the delta is evidenced by (1) increased occurrence of non-storm washover events; (2) increased erosion of barrier islands with average loss of 11 m yr-1 during 1993-1997; and (3) a relative sea-level rise of 3.4 mm yr-1 during 1991-1999. The morphology and recent evolution of the San Juan delta are unique when compared to other deltas of South America because of the singular combination of extreme climatic, geologic, and oceanographic conditions under which the delta has formed and the absence of human-induced impact in the drainage basin. © 2002 Elsevier Science B.V. All rights reserved.
Pollen and diatom based environmental history since the last glacial maximum from the andean core Fuquene-7
(JOHN WILEY & SONS LTD, 2003-01-01) Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Foraminíferos bentónicos recientes en sedimentos de fondo de la cuenca de panamá (pacífico colombiano), como indicadores de productividad y oxigenación
(Instituto de Ivestigaciones Marinas y Costeras-INVEMAR, 2003-01-01) Betancur M.J.; Martínez I.; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Thirteen deep-sea samples (core-tops) from the Panama Basin, Colombian Pacific, were analysed for benthonic foraminifera in the >150µm size fraction. Based on the microfaunal content, three zones are recognised in the Panama Basin: (1) northern euphrophic region (~8° to 5,5°N), characterized by a high concentration of organic matter flux to the seafloor, oxygenated sediments, and influence of the Panama Bight and the Costa Rica Dome upwelling systems, (2) mesotrophic region (~5,5 to 2°N), characterized by low fluxes of organic carbon to the seafloor, oxygenated sediments, terrigenous influence and fluctuations of the upwelling systems of the basin, and (3) southern euphotic region (south of ~2°N), characterized by a larger organic carbon flux to the seafloor, low oxygen content (disoxia) and influence of the Equatorial Divergence.
Pollen-and diatom based environmental history since the Last Glacial Maximum from the Andean core Fúquene-7, Colombia
(JOHN WILEY & SONS LTD, 2003-01-01) Vélez, Maria Isabel; Hooghiemstra, Henry; Metcalfe, Sarah; Martínez, Ignacio; Mommersteeg, Herman; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
The late Pleistocene-Holocene ecological and limnological history of Lake Fúquene (2580 m a.s.l.), in the Colombian Andes, is reconstructed on the basis of diatom, pollen and sediment analyses of the upper 7 m of the core Fúquene-7. Time control is provided by 11 accelerator mass spectrometry (AMS) 14C dates ranging from 19 670 ± 240 to 6040 ± 60 yr BP. In this paper we present the evolution of the lake and its surroundings. Glacial times were cold and dry, lake-levels were low and the area was surrounded by paramo and subparamo vegetation. Late-glacial conditions were warm and humid. The El Abra Stadial, a Younger Dryas equivalent, is reflected by a gap in the sedimentary record, a consequence of the cessation of deposition owing to a drop in lake-level. The early Holocene was warm and humid; at this time the lake reached its maximum extension and was surrounded by Andean forest. The onset of the drier climate prevailing today took place in the middle Holocene, a process that is reflected earlier in the diatom and sediment records than in the pollen records. In the late Holocene human activity reduced the forest and transformed the landscape. Climate patterns from the Late-glacial and throughout the Holocene, as represented in our record, are similar to other records from Colombia and northern South America (the Caribbean, Venezuela and Panama) and suggest that the changes in lake-level were the result of precipitation variations driven by latitudinal shifts of the Intertropical Convergence Zone. © 2003 John Wiley and Sons, Ltd.
The paleoecology of Late Cretaceous upwelling events from the upper Magdalena basin, Colombia
(SEPM-SOC SEDIMENTARY GEOLOGY, 2003-10-01) Martinez, JI; Universidad EAFIT. Departamento de Geología; Ciencias del Mar
Ten planktonic foraminiferal zones are identified and six stratigraphic sequences are interpreted in the Turonian-Maastrichtian interval of the Michu-1 well in the Upper Magdalena Basin. Anoxic bottom-water conditions prevailed during the Turonian and Coniacian followed by dysoxic conditions in the Santonian and Campanian. Oxic conditions were established during the Maastrichtian age. Upwelling occurred for most of the Late Cretaceous. Coccolithophorids, planktonic foraminifera, radialaria, ammonites, clupeoid fish, and mosasaurs dominated the food-web structure of the Turonian-Coniacian interval. Following a major turnover during the Coniacian-Santonian boundary interval, dinoflagellates were the primary producers that sustained radiolarians, a sparse population of planktonic foraminifera, clupeoid fish, and ammonites. Dinaflagellate blooms (peridinoids) were frequent during the Campanian interval and sustained a sparse population of planktonic foraminifera and abundant clupeoid fish whose feces (phosphatic pellets) were grazed extensively by a specialized population of buliminids dominated by the genus Siphogenerinoides.
Introducción al problema de la erosión litoral en Urabá (sector Arboletes - Turbo), Costa Caribe Colombiana
(Instituto de Investigaciones Marinas y Costeras - INVEMAR, 2004) Correa-Arango, Ivan D.; Vernette, Georges; Universidad EAFIT. Departamento de Geología; Ivan D. Correa (icorrea@eafit.edu.co); Ciencias del Mar
Introduction to littoral erosion problem in Urabá (Arboletes-Turbo area) Colombian Caribbean coast. Shoreline retreat has been the net dominant historical trend along the 145 km-length littoral between Arboletes and Turbo (Southern Caribbean of Colombia). For the last four decades, there were identified in this littoral shoreline retreats of about 50-100m in several places (Uveros, Damaquiel, Zapata, Turbo) and a maximun of 1.6 km in the Punta Rey-Arboletes area, where land losses were of 4.5 k m2, at exceptional rates of 40m/year. The synthesis of the available information suggest that the general “susceptibility” to erosion between Arboletes and Turbo could be related primarily to relative sea level rise, associated to tectonic movements as well as to the effects of mud diapirism and hydroisostacy. In the more critical areas (Arboletes, Turbo), the natural erosive trends were accelerated by anthropic actions, including river diversion (Turbo), beach mining, and inadequate (or total absense) practices for controlling residual and natural waters. Up to August 2000, there were invested about $ Col 10.000 billions in 155 engineering defences (groins, sea walls and rip-rap which totalize 6.2 km of total length and a volume of materials of 37.000 m3). With few exceptions, groins have not been successful and are now part of the problem, accelerating shore erosion along the adyacent sectors. In the short term, the littoral erosion between Arboletes and Turbo is caused both by marine and by subaerial factors. It is facilitated by the poor lithological strengths of cliffs and marine terraces, mainly composed of highly fractured and weathered claystones and mudstones (with stratification and weakeness planes dipping toward sea) and nonconsolidated, easily liquefacted, fine sediments; both conditions facilitate the occurrence of rocks falls, slides and mud flows that result in high figures of cliff retreat (3 to 4m), specially during the first 15 days of the summer-winter transition (april) and in high waves periods. The case of the littoral erosion between Arboletes and Turbo illustrates well how the natural erosive trends of an area can be accelerated by human interventions and the urgent need for coordinating efforts to cope with littoral land losses.
El evento Younger Dryas en el norte de Suramérica
(Universidad Industrial de Santander, 2004-01-01) Martinez, Jose Ignacio; Universidad EAFIT. Departamento de Geología; Ciencias del Mar

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