Examinando por Autor "Ignacio Martinez, J."
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Ítem Deep sea benthic foraminifera of the Panama basin: Ecology and their possible relation with deep sea currents(Instituto de Ivestigaciones Marinas y Costeras-INVEMAR, 2013-02-01) Patarroyo, German; Ignacio Martinez, J.; Universidad EAFIT. Departamento de Geología; Ciencias del MarDeep sea benthic foraminifera of the Panama basin: ecology and their possible relation with deep sea currents. The relationship between recent benthic foraminifera and bottom currents in the Panama basin (Colombian Pacific) is examined, and the main ecological variables which control the distribution of benthic foraminifera are discussed. The benthic foraminiferal study of 24 core top samples and the integration with previous reports, support the view that in upwelling areas or under high terrigenous influx, the assemblages are dominated by infaunal forms such as Uvigerina, Bolivina, Globobulimina, and Chilostomella, beside common forms such as Uvigerina peregrina Cushman and Epistominella spp., which are indicative of high productivity. In contrast, epifaunal forms such as Cibicidoides, Laticarinina, and Hoeglundina are more common on the flanks of the Cocos and CarnegieRidges indicating a lower surface productivity and a larger content of dissolved oxygen on the sea foor. Infaunal foraminifera are dominated by Siphouvigerina proboscidea (Schwager). In addition, several proxy taxa of the intensity of deep sea currents were detected in the analyzed assemblages. From these taxa, Cibicides wuellerstorf (Schwager) has the best proxy potential for the reconstruction of intense bottom currents in sediments from the Cocos and Carnegie Ridges for the Holocene.Ítem Ecology of non - marine ostracoda from La Fe reservoir (El Retiro, Antioquia) and their potential application in paleoenvironmental studies(Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 2010-01-01) Torres, Andrea; Ignacio Martinez, J.; Universidad EAFIT. Departamento de Geología; Ciencias del MarLittoral macrophytes from the La Fe reservoir (El Retiro, Antioquia) were sampled for ostracoda during June and September of 2008. This allowed the identification of four genera and six species of ostracoda belonging to the Cyprididae and CandonidaeÍtem El sistema fluvial del Magdalena durante el Plioceno-Cuaternario: contexto tectónico y escenario paleoclimático(Editorial EAFIT, 2005-01-01) Ignacio Martinez, J.Ítem La historia Cenozoica del fenómeno de El Niño(Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 2009-12-01) Ignacio Martinez, J.; Universidad EAFIT. Departamento de Geología; Ciencias del MarDurante la era Cenozoica cuatro intervalos de tiempo: el Eoceno temprano (~50 Ma), el Plioceno temprano (~5-3 Ma), el ultimo glacial máximo (~20 ka) y el Holoceno (<10 ka), han sido examinados en detalle en un esfuerzo para entender el fenómeno de El NiñoÍtem 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 A Mid-Late Holocene History of the Floodplain Lakes of the Cauca River, Colombia.(SPRINGER, 2013-01-01) Velez, M I; Ignacio Martinez, J.; Suter, F; Universidad EAFIT. Departamento de Geología; Ciencias del MarWe conducted a paleolimnological investigation of late Holocene deposits on a distal, constrained floodplain of the Cauca River, northern Colombia, i.e. the La Caimana sedimentary succession. The record starts sometime betweenÍtem Palynofacies analysis of the late Holocene San Nicolás terrace of the Cauca paleolake and paleohydrology of northern South America(ELSEVIER SCIENCE BV, 2011-01-01) Garcia, Yuri C.; Ignacio Martinez, J.; Velez, Maria I.; Yokoyama, Yusuke; Battarbee, Richard W.; Suter, Fiore D.; Universidad EAFIT. Departamento de Geología; Ciencias del MarThe detailed palynofacies analysis of the late Holocene laminated succession of the San Nicolás terrace in the middle Cauca Valley, northern Colombia, is interpreted as the product of sedimentation in a lacustrine to fluvial dominated setting. Radiocarbon analyses reveal that the succession was deposited between ~. 3500 and a few hundreds of years with sedimentary rates in excess of ~. 600. cm/ka. The milimetric laminae and the high frequency fluctuations in the content of the palynodebris of terrestrial origin, i.e., the high altered ligno-cellulosic debris/amorphous organic matter ratio, together with diatoms typical of fluvial conditions, such as Aulacoseira granulata do suggest an intermittent and continuous hydrological and biological connectivity with the Cauca River, akin to a varzea lacustrine environment. Drier to wetter conditions appear to occur, moving upward in the succession. This might reflect regional precipitation conditions all along the Cauca Valley and the southern migration of the intertropical convergence zone. © 2010 Elsevier B.V.Ítem El periodo cálido medieval y la pequeña edad de hielo en el neotrópico(Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 2009-12-01) García, Yuri Carolina; Ignacio Martinez, J.; Universidad EAFIT. Departamento de Geología; Ciencias del MarEn el Neotrópico existen registros paleoclimáticos marinos y continentales que sugieren la ocurrencia de condiciones relacionadas con el Período Cálido Medieval (MWP, ~800-1300 AD) y la Pequeña Edad de Hielo (LIA, ~1300-1800 AD).Ítem Postglacial North Pacific(Elsevier, 2013-01-01) Ignacio Martinez, J.Postglacial North Pacific paleoceanography is dominated by the ENSO system, which can acquire for centuries to thousands of years an El Niño-like or a La Niña-like dominant state. A La Niña-like (negative Pacific decadal oscillation (PDO)) to El Niño-like (positive PDO) state evolved from the early-middle to the late Holocene. Accordingly, the ITCZ changed from a northern to a southern location, thus reducing the strength of the Kuroshio and California Currents. In addition to this pattern, there are regional differences imposed by the interaction between the monsoons in the western Pacific and the PDO in the northeastern Pacific. Evidence is becoming robust for teleconnections between the Asian monsoons, the California Current, and the Atlantic meridional overturning circulation, modulated by solar insolation and ice sheet dynamics. © 2013 Elsevier B.V. All rights reserved.Ítem The San Nicolás succession of the Cauca paleolake: A late Holocene laminated ria lake record from the Neotropics(SPRINGER, 2013-02-01) Ignacio Martinez, J.; Mayr, Christoph; Yokoyama, Yusuke; Velez, Maria I.; Battarbee, Richard W.; Universidad EAFIT. Departamento de Geología; Ciencias del MarThe stratigraphic, geochemical, and organic matter study of the late Holocene San Nicolás succession of the Cauca paleolake (Santa Fé-Sopetrán pull-apart basin) in the middle Cauca Valley, northern Colombia, suggests that it was deposited in a ria lake environment, at sedimentary accumulation rates in excess of 600 cm ky-1 between ~3500 and ~500 yr BP. Laminated deposition occurred, first under igapo (black-water), and then under varzea (white-water) conditions. The transition occurred ca. 3000 yr BP, a time of major change in El Niño/Southern Oscillation (ENSO) behavior in the Cariaco Basin, thus reflecting the southern migration of the intertropical convergence zone and intensified rain upstream the Cauca Valley. A second, but less conspicuous change occurred ca. 2000 yr BP, which apparently corresponds to the intensified and/or more frequent ENSO activity in the Galapagos Islands. Our contribution describes, for the first time, a ria lake sedimentary succession from the northern Andes and demonstrates the high potential of these hitherto undervalued deposits for the reconstruction of the paleohydrological history of the northern Andes. © 2012 Springer Science+Business Media Dordrecht.Ítem Sedimentación Reciente de la Cuenca de Panamá y el márgen Pacífico Colombiano(Editorial EAFIT, 2002-01-01) Ignacio Martinez, J.